diff --git a/lib/net/http.rb b/lib/net/http.rb
index 7fd4c3ed..44d31472 100644
--- a/lib/net/http.rb
+++ b/lib/net/http.rb
@@ -761,11 +761,23 @@ class << HTTP
     # Like Net::HTTP.get, but writes the returned body to $stdout;
     # returns +nil+.
     def HTTP.get_print(uri_or_host, path_or_headers = nil, port = nil)
-      get_response(uri_or_host, path_or_headers, port) {|res|
-        res.read_body do |chunk|
-          $stdout.print chunk
-        end
-      }
+      if path_or_headers && !path_or_headers.is_a?(Hash)
+        host = uri_or_host #: String
+        path = path_or_headers #: String
+        get_response(host, path, port) {|res|
+          res.read_body do |chunk|
+            $stdout.print chunk
+          end
+        }
+      else
+        uri = uri_or_host #: URI::HTTP
+        headers = path_or_headers #: headers?
+        get_response(uri, headers) {|res|
+          res.read_body do |chunk|
+            $stdout.print chunk
+          end
+        }
+      end
       nil
     end
 
@@ -802,7 +814,15 @@ def HTTP.get_print(uri_or_host, path_or_headers = nil, port = nil)
     # - Net::HTTP#get: convenience method for \HTTP method +GET+.
     #
     def HTTP.get(uri_or_host, path_or_headers = nil, port = nil)
-      get_response(uri_or_host, path_or_headers, port).body
+      if path_or_headers && !path_or_headers.is_a?(Hash)
+        host = uri_or_host #: String
+        path = path_or_headers #: String
+        get_response(host, path, port).body
+      else
+        uri = uri_or_host #: URI::HTTP
+        headers = path_or_headers #: headers?
+        get_response(uri, headers).body
+      end
     end
 
     # :call-seq:
@@ -813,15 +833,16 @@ def HTTP.get(uri_or_host, path_or_headers = nil, port = nil)
     # instead of the body string.
     def HTTP.get_response(uri_or_host, path_or_headers = nil, port = nil, &block)
       if path_or_headers && !path_or_headers.is_a?(Hash)
-        host = uri_or_host
-        path = path_or_headers
+        host = uri_or_host #: String
+        path = path_or_headers #: String
         new(host, port || HTTP.default_port).start {|http|
           return http.request_get(path, &block)
         }
       else
-        uri = uri_or_host
-        headers = path_or_headers
-        start(uri.hostname, uri.port,
+        uri = uri_or_host #: URI::HTTP
+        headers = path_or_headers #: headers?
+        hostname = uri.hostname or raise ArgumentError, "no host component for URI"
+        start(hostname, uri.port,
               :use_ssl => uri.scheme == 'https') {|http|
           return http.request_get(uri, headers, &block)
         }
@@ -855,7 +876,8 @@ def HTTP.get_response(uri_or_host, path_or_headers = nil, port = nil, &block)
     # - Net::HTTP#post: convenience method for \HTTP method +POST+.
     #
     def HTTP.post(url, data, header = nil)
-      start(url.hostname, url.port,
+      hostname = url.hostname or raise ArgumentError, "no host component for URI"
+      start(hostname, url.port,
             :use_ssl => url.scheme == 'https' ) {|http|
         http.post(url, data, header)
       }
@@ -884,8 +906,11 @@ def HTTP.post(url, data, header = nil)
     def HTTP.post_form(url, params)
       req = Post.new(url)
       req.form_data = params
-      req.basic_auth url.user, url.password if url.user
-      start(url.hostname, url.port,
+      if user = url.user
+        req.basic_auth(user, url.password.to_s)
+      end
+      hostname = url.hostname or raise ArgumentError, "no host component for URI"
+      start(hostname, url.port,
             :use_ssl => url.scheme == 'https' ) {|http|
         http.request(req)
       }
@@ -918,7 +943,8 @@ def HTTP.post_form(url, params)
     # - Net::HTTP#put: convenience method for \HTTP method +PUT+.
     #
     def HTTP.put(url, data, header = nil)
-      start(url.hostname, url.port,
+      hostname = url.hostname or raise ArgumentError, "no host component for URI"
+      start(hostname, url.port,
             :use_ssl => url.scheme == 'https' ) {|http|
         http.put(url, data, header)
       }
@@ -1054,14 +1080,22 @@ def HTTP.start(address, *arg, &block) # :yield: +http+
         if opt[:use_ssl]
           opt = {verify_mode: OpenSSL::SSL::VERIFY_PEER}.update(opt)
         end
-        http.methods.grep(/\A(\w+)=\z/) do |meth|
-          key = $1.to_sym
-          opt.key?(key) or next
+        http.methods.grep(/\A(\w+)=\z/).each do |meth|
+          match = /\A(\w+)=\z/.match(meth.to_s)
+          next unless match
+          key = match[1]
+          next unless key
+          key = key.to_sym
+          next unless opt.key?(key)
           http.__send__(meth, opt[key])
         end
       end
 
-      http.start(&block)
+      if block
+        http.start(&block)
+      else
+        http.start
+      end
     end
 
     class << HTTP
@@ -1098,7 +1132,7 @@ class << HTTP
     # see {Proxy Server}[rdoc-ref:Net::HTTP@Proxy+Server].
     #
     def HTTP.new(address, port = nil, p_addr = :ENV, p_port = nil, p_user = nil, p_pass = nil, p_no_proxy = nil, p_use_ssl = nil)
-      http = super address, port
+      http = newobj(address, port)
 
       if proxy_class? then # from Net::HTTP::Proxy()
         http.proxy_from_env = @proxy_from_env
@@ -1107,14 +1141,14 @@ def HTTP.new(address, port = nil, p_addr = :ENV, p_port = nil, p_user = nil, p_p
         http.proxy_user     = @proxy_user
         http.proxy_pass     = @proxy_pass
         http.proxy_use_ssl  = @proxy_use_ssl
-      elsif p_addr == :ENV then
+      elsif p_addr.is_a?(Symbol) && p_addr == :ENV then
         http.proxy_from_env = true
       else
-        if p_addr && p_no_proxy && !URI::Generic.use_proxy?(address, address, port, p_no_proxy)
+        if p_addr && p_no_proxy && !URI::Generic.use_proxy?(address, address, port || default_port, p_no_proxy)
           p_addr = nil
           p_port = nil
         end
-        http.proxy_address = p_addr
+        http.proxy_address = p_addr&.to_s
         http.proxy_port    = p_port || default_port
         http.proxy_user    = p_user
         http.proxy_pass    = p_pass
@@ -1347,7 +1381,12 @@ def response_body_encoding=(value)
     #   http.finish
     #
     def ipaddr
-      started? ?  @socket.io.peeraddr[3] : @ipaddr
+      if started?
+        socket = @socket or return @ipaddr
+        socket.io.peeraddr[3]
+      else
+        @ipaddr
+      end
     end
 
     # Sets the IP address for the connection:
@@ -1416,7 +1455,9 @@ def max_retries=(retries)
     #   http.get('/todos/1') # Raises Net::ReadTimeout.
     #
     def read_timeout=(sec)
-      @socket.read_timeout = sec if @socket
+      if (socket = @socket)
+        socket.read_timeout = sec
+      end
       @read_timeout = sec
     end
 
@@ -1440,7 +1481,9 @@ def read_timeout=(sec)
     #   http.post(_uri.path, data, headers) # Raises Net::WriteTimeout.
     #
     def write_timeout=(sec)
-      @socket.write_timeout = sec if @socket
+      if (socket = @socket)
+        socket.write_timeout = sec
+      end
       @write_timeout = sec
     end
 
@@ -1453,7 +1496,9 @@ def write_timeout=(sec)
     # If the \HTTP object does not receive a response in this many seconds
     # it sends the request body.
     def continue_timeout=(sec)
-      @socket.continue_timeout = sec if @socket
+      if (socket = @socket)
+        socket.continue_timeout = sec
+      end
       @continue_timeout = sec
     end
 
@@ -1595,10 +1640,11 @@ def use_ssl=(flag)
     # for the session's socket peer,
     # or +nil+ if none.
     def peer_cert
-      if not use_ssl? or not @socket
+      socket = @socket
+      if !use_ssl? || !socket
         return nil
       end
-      @socket.io.peer_cert
+      socket.io.peer_cert
     end
 
     # Starts an \HTTP session.
@@ -1676,7 +1722,8 @@ def connect
       begin
         s = timeouted_connect(conn_addr, conn_port)
       rescue => e
-        if (defined?(IO::TimeoutError) && e.is_a?(IO::TimeoutError)) || e.is_a?(Errno::ETIMEDOUT)  # for compatibility with previous versions
+        timeout_error = IO.const_get(:TimeoutError, false) if IO.const_defined?(:TimeoutError, false)
+        if (timeout_error && e.is_a?(timeout_error)) || e.is_a?(Errno::ETIMEDOUT)  # for compatibility with previous versions
           e = Net::OpenTimeout.new(e)
         end
         raise e, "Failed to open TCP connection to " +
@@ -1718,19 +1765,23 @@ def connect
             end
           end
         end
-        @ssl_context.set_params(ssl_parameters)
-        unless @ssl_context.session_cache_mode.nil? # a dummy method on JRuby
-          @ssl_context.session_cache_mode =
+        ssl_context = @ssl_context or raise OpenSSL::SSL::SSLError, 'SSL context not initialized'
+        ssl_context.set_params(ssl_parameters)
+        unless ssl_context.session_cache_mode.nil? # a dummy method on JRuby
+          ssl_context.session_cache_mode =
               OpenSSL::SSL::SSLContext::SESSION_CACHE_CLIENT |
                   OpenSSL::SSL::SSLContext::SESSION_CACHE_NO_INTERNAL_STORE
         end
-        if @ssl_context.respond_to?(:session_new_cb) # not implemented under JRuby
-          @ssl_context.session_new_cb = proc {|sock, sess| @ssl_session = sess }
+        if ssl_context.respond_to?(:session_new_cb) # not implemented under JRuby
+          ssl_context.session_new_cb = ->(socket_or_pair) do
+            socket, session = Array(socket_or_pair)
+            @ssl_session = session || socket.session
+          end
         end
 
         # Still do the post_connection_check below even if connecting
         # to IP address
-        verify_hostname = @ssl_context.verify_hostname
+        verify_hostname = ssl_context.verify_hostname
 
         # Server Name Indication (SNI) RFC 3546/6066
         case @address
@@ -1739,25 +1790,26 @@ def connect
           # per RFC 6066, section 3.
 
           # Avoid openssl warning
-          @ssl_context.verify_hostname = false
+          ssl_context.verify_hostname = false
         else
           ssl_host_address = @address
         end
 
         debug "starting SSL for #{conn_addr}:#{conn_port}..."
-        s = OpenSSL::SSL::SSLSocket.new(s, @ssl_context)
+        s = OpenSSL::SSL::SSLSocket.new(s, ssl_context)
         s.sync_close = true
         s.hostname = ssl_host_address if s.respond_to?(:hostname=) && ssl_host_address
 
-        if @ssl_session and
-           Process.clock_gettime(Process::CLOCK_REALTIME) < @ssl_session.time.to_f + @ssl_session.timeout
-          s.session = @ssl_session
+        if (ssl_session = @ssl_session) &&
+           Process.clock_gettime(Process::CLOCK_REALTIME) < ssl_session.time.to_f + ssl_session.timeout
+          s.session = ssl_session
         end
         ssl_socket_connect(s, @open_timeout)
-        if (@ssl_context.verify_mode != OpenSSL::SSL::VERIFY_NONE) && verify_hostname
+        if (ssl_context.verify_mode != OpenSSL::SSL::VERIFY_NONE) && verify_hostname
           s.post_connection_check(@address)
         end
-        debug "SSL established, protocol: #{s.ssl_version}, cipher: #{s.cipher[0]}"
+        cipher = s.cipher
+        debug "SSL established, protocol: #{s.ssl_version}, cipher: #{cipher ? cipher[0] : nil}"
       end
       @socket = BufferedIO.new(s, read_timeout: @read_timeout,
                                write_timeout: @write_timeout,
@@ -1785,11 +1837,13 @@ def connect
     private_constant :TCP_SOCKET_NEW_HAS_OPEN_TIMEOUT
 
     def timeouted_connect(conn_addr, conn_port)
+      conn_addr = conn_addr or raise ArgumentError, "missing connection address"
+      conn_port = conn_port or raise ArgumentError, "missing connection port"
       if TCP_SOCKET_NEW_HAS_OPEN_TIMEOUT
-        TCPSocket.open(conn_addr, conn_port, @local_host, @local_port, open_timeout: @open_timeout)
+        TCPSocket.new(conn_addr, conn_port, @local_host, @local_port, open_timeout: @open_timeout)
       else
         Timeout.timeout(@open_timeout, Net::OpenTimeout) {
-          TCPSocket.open(conn_addr, conn_port, @local_host, @local_port)
+          TCPSocket.new(conn_addr, conn_port, @local_host, @local_port)
         }
       end
     end
@@ -1801,7 +1855,9 @@ def on_connect
 
     def do_finish
       @started = false
-      @socket.close if @socket
+      if (socket = @socket)
+        socket.close
+      end
       @socket = nil
     end
     private :do_finish
@@ -1832,13 +1888,14 @@ def HTTP.Proxy(p_addr = :ENV, p_port = nil, p_user = nil, p_pass = nil, p_use_ss
       Class.new(self) {
         @is_proxy_class = true
 
-        if p_addr == :ENV then
+        case p_addr
+        when :ENV
           @proxy_from_env = true
           @proxy_address = nil
           @proxy_port    = nil
         else
           @proxy_from_env = false
-          @proxy_address = p_addr
+          @proxy_address = String(p_addr)
           @proxy_port    = p_port || default_port
         end
 
@@ -2011,13 +2068,14 @@ def edit_path(path)
     # - Net::HTTP.get: sends GET request, returns response body.
     #
     def get(path, initheader = nil, dest = nil, &block) # :yield: +body_segment+
-      res = nil
-
       request(Get.new(path, initheader)) {|r|
-        r.read_body dest, &block
-        res = r
+        if block
+          raise ArgumentError, 'both arg and block given for HTTP method' if dest
+          r.read_body(&block)
+        else
+          r.read_body(dest)
+        end
       }
-      res
     end
 
     # Sends a HEAD request to the server;
@@ -2404,7 +2462,7 @@ def request(req, body = nil, &block)  # :yield: +response+
         }
       end
       if proxy_user()
-        req.proxy_basic_auth proxy_user(), proxy_pass() unless use_ssl?
+        req.proxy_basic_auth proxy_user(), proxy_pass().to_s unless use_ssl?
       end
       req.set_body_internal body
       res = transport_request(req, &block)
@@ -2420,12 +2478,14 @@ def request(req, body = nil, &block)  # :yield: +response+
     # Executes a request which uses a representation
     # and returns its body.
     def send_entity(path, data, initheader, dest, type, &block)
-      res = nil
       request(type.new(path, initheader), data) {|r|
-        r.read_body dest, &block
-        res = r
+        if block
+          raise ArgumentError, 'both arg and block given for HTTP method' if dest
+          r.read_body(&block)
+        else
+          r.read_body(dest)
+        end
       }
-      res
     end
 
     # :stopdoc:
@@ -2437,24 +2497,29 @@ def transport_request(req)
       begin
         begin_transport req
         res = catch(:response) {
+          socket = @socket or raise IOError, 'HTTP session not yet started'
           begin
-            req.exec @socket, @curr_http_version, edit_path(req.path)
+            req.exec socket, @curr_http_version, edit_path(req.path)
           rescue Errno::EPIPE
             # Failure when writing full request, but we can probably
             # still read the received response.
           end
 
-          begin
-            res = HTTPResponse.read_new(@socket)
+          res = HTTPResponse.read_new(socket)
+          loop do
             res.decode_content = req.decode_content
             res.body_encoding = @response_body_encoding
             res.ignore_eof = @ignore_eof
-          end while res.kind_of?(HTTPInformation)
+            break unless res.kind_of?(HTTPInformation)
+            res = HTTPResponse.read_new(socket)
+          end
 
-          res.uri = req.uri
+          response = res or raise Net::HTTPBadResponse, 'no HTTP response'
+          response.uri = req.uri if req.uri
 
-          res
+          response
         }
+        res = res or raise Net::HTTPBadResponse, 'no HTTP response'
         res.reading_body(@socket, req.response_body_permitted?) {
           if block_given?
             count = max_retries # Don't restart in the middle of a download
@@ -2470,12 +2535,16 @@ def transport_request(req)
              Timeout::Error => exception
         if count < max_retries && IDEMPOTENT_METHODS_.include?(req.method)
           count += 1
-          @socket.close if @socket
+          if (socket = @socket)
+            socket.close
+          end
           debug "Conn close because of error #{exception}, and retry"
           retry
         end
         debug "Conn close because of error #{exception}"
-        @socket.close if @socket
+        if (socket = @socket)
+          socket.close
+        end
         raise
       end
 
@@ -2483,21 +2552,25 @@ def transport_request(req)
       res
     rescue => exception
       debug "Conn close because of error #{exception}"
-      @socket.close if @socket
+      if (socket = @socket)
+        socket.close
+      end
       raise exception
     end
 
     def begin_transport(req)
-      if @socket.closed?
+      socket = @socket or raise IOError, 'HTTP session not yet started'
+      if socket.closed?
         connect
       elsif @last_communicated
-        if @last_communicated + @keep_alive_timeout < Process.clock_gettime(Process::CLOCK_MONOTONIC)
+        last_communicated = @last_communicated
+        if last_communicated && last_communicated + @keep_alive_timeout < Process.clock_gettime(Process::CLOCK_MONOTONIC)
           debug 'Conn close because of keep_alive_timeout'
-          @socket.close
+          socket.close
           connect
-        elsif @socket.io.to_io.wait_readable(0) && @socket.eof?
+        elsif socket.io.to_io.wait_readable(0) && socket.eof?
           debug "Conn close because of EOF"
-          @socket.close
+          socket.close
           connect
         end
       end
@@ -2511,19 +2584,20 @@ def begin_transport(req)
     end
 
     def end_transport(req, res)
-      @curr_http_version = res.http_version
+      @curr_http_version = res.http_version || HTTPVersion
       @last_communicated = nil
-      if @socket.closed?
+      socket = @socket or raise IOError, 'HTTP session not yet started'
+      if socket.closed?
         debug 'Conn socket closed'
       elsif not res.body and @close_on_empty_response
         debug 'Conn close'
-        @socket.close
+        socket.close
       elsif keep_alive?(req, res)
         debug 'Conn keep-alive'
         @last_communicated = Process.clock_gettime(Process::CLOCK_MONOTONIC)
       else
         debug 'Conn close'
-        @socket.close
+        socket.close
       end
     end
 
@@ -2539,7 +2613,7 @@ def keep_alive?(req, res)
     def sspi_auth?(res)
       return false unless @sspi_enabled
       if res.kind_of?(HTTPProxyAuthenticationRequired) and
-          proxy? and res["Proxy-Authenticate"].include?("Negotiate")
+          proxy? and res["Proxy-Authenticate"].to_s.include?("Negotiate")
         begin
           require 'win32/sspi'
           true
@@ -2579,9 +2653,9 @@ def addr_port
 
     # Adds a message to debugging output
     def debug(msg)
-      return unless @debug_output
-      @debug_output << msg
-      @debug_output << "\n"
+      output = @debug_output or return
+      output << msg
+      output << "\n"
     end
 
     alias_method :D, :debug
diff --git a/lib/net/http/generic_request.rb b/lib/net/http/generic_request.rb
index 5b01ea4a..792cef7e 100644
--- a/lib/net/http/generic_request.rb
+++ b/lib/net/http/generic_request.rb
@@ -14,8 +14,8 @@ class Net::HTTPGenericRequest
 
   def initialize(m, reqbody, resbody, uri_or_path, initheader = nil) # :nodoc:
     @method = m
-    @request_has_body = reqbody
-    @response_has_body = resbody
+    @request_has_body = reqbody ? true : false
+    @response_has_body = resbody ? true : false
 
     if URI === uri_or_path then
       raise ArgumentError, "not an HTTP URI" unless URI::HTTP === uri_or_path
@@ -36,10 +36,10 @@ def initialize(m, reqbody, resbody, uri_or_path, initheader = nil) # :nodoc:
     if Net::HTTP::HAVE_ZLIB then
       if !initheader ||
          !initheader.keys.any? { |k|
-           %w[accept-encoding range].include? k.downcase
+           %w[accept-encoding range].include? k.to_s.downcase
          } then
         @decode_content = true if @response_has_body
-        initheader = initheader ? initheader.dup : {}
+        initheader = initheader ? initheader.dup : {} #: Hash[String | Symbol, untyped]
         initheader["accept-encoding"] =
           "gzip;q=1.0,deflate;q=0.6,identity;q=0.3"
       end
@@ -48,7 +48,9 @@ def initialize(m, reqbody, resbody, uri_or_path, initheader = nil) # :nodoc:
     initialize_http_header initheader
     self['Accept'] ||= '*/*'
     self['User-Agent'] ||= 'Ruby'
-    self['Host'] ||= @uri.authority if @uri
+    if (uri = @uri)
+      self['Host'] ||= uri.authority
+    end
     @body = nil
     @body_stream = nil
     @body_data = nil
@@ -129,7 +131,7 @@ def pretty_print(q)
   # they want to handle it.
 
   def []=(key, val) # :nodoc:
-    @decode_content = false if key.downcase == 'accept-encoding'
+    @decode_content = false if key.to_s.downcase == 'accept-encoding'
 
     super key, val
   end
@@ -218,12 +220,12 @@ def set_body_internal(str)   #:nodoc: internal use only
   #
 
   def exec(sock, ver, path)   #:nodoc: internal use only
-    if @body
-      send_request_with_body sock, ver, path, @body
-    elsif @body_stream
-      send_request_with_body_stream sock, ver, path, @body_stream
-    elsif @body_data
-      send_request_with_body_data sock, ver, path, @body_data
+    if body = @body
+      send_request_with_body sock, ver, path, body
+    elsif body_stream = @body_stream
+      send_request_with_body_stream sock, ver, path, body_stream
+    elsif body_data = @body_data
+      send_request_with_body_data sock, ver, path, body_data
     else
       write_header sock, ver, path
     end
@@ -231,7 +233,7 @@ def exec(sock, ver, path)   #:nodoc: internal use only
 
   def update_uri(addr, port, ssl) # :nodoc: internal use only
     # reflect the connection and @path to @uri
-    return unless @uri
+    uri = @uri or return
 
     if ssl
       scheme = 'https'
@@ -243,19 +245,19 @@ def update_uri(addr, port, ssl) # :nodoc: internal use only
 
     if host = self['host']
       host = URI.parse("//#{host}").host # Remove a port component from the existing Host header
-    elsif host = @uri.host
+    elsif host = uri.host
     else
      host = addr
     end
     # convert the class of the URI
-    if @uri.is_a?(klass)
-      @uri.host = host
-      @uri.port = port
+    if uri.is_a?(klass)
+      uri.host = host
+      uri.port = port
     else
       @uri = klass.new(
-        scheme, @uri.userinfo,
+        scheme, uri.userinfo,
         host, port, nil,
-        @uri.path, nil, @uri.query, nil)
+        uri.path, nil, uri.query, nil)
     end
   end
 
@@ -266,13 +268,13 @@ def update_uri(addr, port, ssl) # :nodoc: internal use only
   class Chunker #:nodoc:
     def initialize(sock)
       @sock = sock
-      @prev = nil
     end
 
-    def write(buf)
+    def write(*buf)
       # avoid memcpy() of buf, buf can huge and eat memory bandwidth
-      rv = buf.bytesize
-      @sock.write("#{rv.to_s(16)}\r\n", buf, "\r\n")
+      chunk = buf.join
+      rv = chunk.bytesize
+      @sock.write("#{rv.to_s(16)}\r\n", chunk, "\r\n")
       rv
     end
 
@@ -314,7 +316,7 @@ def send_request_with_body_data(sock, ver, path, params)
     opt = @form_option.dup
     require 'securerandom' unless defined?(SecureRandom)
     opt[:boundary] ||= SecureRandom.urlsafe_base64(40)
-    self.set_content_type(self.content_type, boundary: opt[:boundary])
+    self.set_content_type(self.content_type.to_s, boundary: opt[:boundary])
     if chunked?
       write_header sock, ver, path
       encode_multipart_form_data(sock, params, opt)
diff --git a/lib/net/http/header.rb b/lib/net/http/header.rb
index 797a3bea..abfa4cd3 100644
--- a/lib/net/http/header.rb
+++ b/lib/net/http/header.rb
@@ -185,7 +185,7 @@ module Net::HTTPHeader
   MAX_FIELD_LENGTH = 65536
 
   def initialize_http_header(initheader) #:nodoc:
-    @header = {}
+    @header = {} #: Hash[String, Array[String]]
     return unless initheader
     initheader.each do |key, value|
       warn "net/http: duplicated HTTP header: #{key}", uplevel: 3 if key?(key) and $VERBOSE
@@ -202,7 +202,7 @@ def initialize_http_header(initheader) #:nodoc:
         if value.count("\r\n") > 0
           raise ArgumentError, "header #{key} has field value #{value.inspect}, this cannot include CR/LF"
         end
-        @header[key.downcase.to_s] = [value]
+        @header[key.to_s.downcase] = [value]
       end
     end
   end
@@ -224,7 +224,7 @@ def size   #:nodoc: obsolete
   # Note that some field values may be retrieved via convenience methods;
   # see {Getters}[rdoc-ref:Net::HTTPHeader@Getters].
   def [](key)
-    a = @header[key.downcase.to_s] or return nil
+    a = @header[String(key).downcase] or return nil
     a.join(', ')
   end
 
@@ -241,7 +241,7 @@ def [](key)
   # see {Setters}[rdoc-ref:Net::HTTPHeader@Setters].
   def []=(key, val)
     unless val
-      @header.delete key.downcase.to_s
+      @header.delete String(key).downcase
       return val
     end
     set_field(key, val)
@@ -261,7 +261,7 @@ def []=(key, val)
   #   req.get_fields('Foo') # => ["bar", "baz", "baz", "bam"]
   #
   def add_field(key, val)
-    stringified_downcased_key = key.downcase.to_s
+    stringified_downcased_key = String(key).downcase
     if @header.key?(stringified_downcased_key)
       append_field_value(@header[stringified_downcased_key], val)
     else
@@ -273,15 +273,15 @@ def add_field(key, val)
   private def set_field(key, val)
     case val
     when Enumerable
-      ary = []
+      ary = [] #: Array[String]
       append_field_value(ary, val)
-      @header[key.downcase.to_s] = ary
+      @header[String(key).downcase] = ary
     else
       val = val.to_s # for compatibility use to_s instead of to_str
       if val.b.count("\r\n") > 0
         raise ArgumentError, 'header field value cannot include CR/LF'
       end
-      @header[key.downcase.to_s] = [val]
+      @header[String(key).downcase] = [val]
     end
   end
 
@@ -308,7 +308,7 @@ def add_field(key, val)
   #   res.get_fields('Nosuch')     # => nil
   #
   def get_fields(key)
-    stringified_downcased_key = key.downcase.to_s
+    stringified_downcased_key = String(key).downcase
     return nil unless @header[stringified_downcased_key]
     @header[stringified_downcased_key].dup
   end
@@ -343,7 +343,17 @@ def get_fields(key)
   #   res.fetch('Nosuch')            # Raises KeyError.
   #
   def fetch(key, *args, &block)   #:yield: +key+
-    a = @header.fetch(key.downcase.to_s, *args, &block)
+    key = String(key).downcase
+    a = if (value = @header[key])
+      value
+    elsif block
+      handler = block
+      return handler.call(key)
+    elsif args.empty?
+      @header.fetch(key)
+    else
+      return args.first
+    end
     a.kind_of?(Array) ? a.join(', ') : a
   end
 
@@ -366,7 +376,7 @@ def fetch(key, *args, &block)   #:yield: +key+
   #
   # Net::HTTPHeader#each is an alias for Net::HTTPHeader#each_header.
   def each_header   #:yield: +key+, +value+
-    block_given? or return enum_for(__method__) { @header.size }
+    block_given? or return enum_for(:each_header) { @header.size }
     @header.each do |k,va|
       yield k, va.join(', ')
     end
@@ -393,8 +403,11 @@ def each_header   #:yield: +key+, +value+
   #
   # Net::HTTPHeader#each_name is an alias for Net::HTTPHeader#each_key.
   def each_name(&block)   #:yield: +key+
-    block_given? or return enum_for(__method__) { @header.size }
-    @header.each_key(&block)
+    block_given? or return enum_for(:each_name) { @header.size }
+    handler = block or return enum_for(:each_name) { @header.size }
+    @header.each_key do |key|
+      handler.call(key)
+    end
   end
 
   alias each_key each_name
@@ -419,7 +432,7 @@ def each_name(&block)   #:yield: +key+
   #
   # Returns an enumerator if no block is given.
   def each_capitalized_name  #:yield: +key+
-    block_given? or return enum_for(__method__) { @header.size }
+    block_given? or return enum_for(:each_capitalized_name) { @header.size }
     @header.each_key do |k|
       yield capitalize(k)
     end
@@ -440,7 +453,7 @@ def each_capitalized_name  #:yield: +key+
   #
   # Returns an enumerator if no block is given.
   def each_value   #:yield: +value+
-    block_given? or return enum_for(__method__) { @header.size }
+    block_given? or return enum_for(:each_value) { @header.size }
     @header.each_value do |va|
       yield va.join(', ')
     end
@@ -455,7 +468,7 @@ def each_value   #:yield: +value+
   #   req.delete('Nosuch') # => nil
   #
   def delete(key)
-    @header.delete(key.downcase.to_s)
+    @header.delete(String(key).downcase)
   end
 
   # Returns +true+ if the field for the case-insensitive +key+ exists, +false+ otherwise:
@@ -465,7 +478,7 @@ def delete(key)
   #   req.key?('Nosuch') # => false
   #
   def key?(key)
-    @header.key?(key.downcase.to_s)
+    @header.key?(String(key).downcase)
   end
 
   # Returns a hash of the key/value pairs:
@@ -486,7 +499,7 @@ def to_hash
   #
   # Net::HTTPHeader#canonical_each is an alias for Net::HTTPHeader#each_capitalized.
   def each_capitalized
-    block_given? or return enum_for(__method__) { @header.size }
+    block_given? or return enum_for(:each_capitalized) { @header.size }
     @header.each do |k,v|
       yield capitalize(k), v.join(', ')
     end
@@ -524,7 +537,7 @@ def range
       raise Net::HTTPHeaderSyntaxError, "invalid syntax for byte-ranges-specifier: '#{value}'"
     end
 
-    byte_range_set = $1
+    byte_range_set = $1.to_s
     result = byte_range_set.split(/,/).map {|spec|
       m = /(\d+)?\s*-\s*(\d+)?/i.match(spec) or
               raise Net::HTTPHeaderSyntaxError, "invalid byte-range-spec: '#{spec}'"
@@ -582,10 +595,14 @@ def set_range(r, e = nil)
       @header.delete 'range'
       return r
     end
-    r = (r...r+e) if e
+    if e
+      first = Integer(r) or raise TypeError, 'Range/Integer is required'
+      length = Integer(e) or raise TypeError, 'Range/Integer is required'
+      r = first...(first + length)
+    end
     case r
     when Numeric
-      n = r.to_i
+      n = Integer(r)
       rangestr = (n > 0 ? "0-#{n-1}" : "-#{-n}")
     when Range
       first = r.first
@@ -619,7 +636,7 @@ def set_range(r, e = nil)
   #
   def content_length
     return nil unless key?('Content-Length')
-    len = self['Content-Length'].slice(/\d+/) or
+    len = self['Content-Length'].to_s.slice(/\d+/) or
         raise Net::HTTPHeaderSyntaxError, 'wrong Content-Length format'
     len.to_i
   end
@@ -726,7 +743,7 @@ def content_type
   #
   def main_type
     return nil unless @header['content-type']
-    self['Content-Type'].split(';').first.to_s.split('/')[0].to_s.strip
+    self['Content-Type'].to_s.split(';').first.to_s.split('/')[0].to_s.strip
   end
 
   # Returns the trailing ('subtype') part of the
@@ -741,7 +758,7 @@ def main_type
   #
   def sub_type
     return nil unless @header['content-type']
-    _, sub = *self['Content-Type'].split(';').first.to_s.split('/')
+    _, sub = *self['Content-Type'].to_s.split(';').first.to_s.split('/')
     return nil unless sub
     sub.strip
   end
@@ -755,11 +772,12 @@ def sub_type
   #   res.type_params     # => {"charset"=>"utf-8"}
   #
   def type_params
-    result = {}
+    result = {} #: Hash[String, String]
     list = self['Content-Type'].to_s.split(';')
     list.shift
     list.each do |param|
       k, v = *param.split('=', 2)
+      next unless k && v
       result[k.strip] = v.strip
     end
     result
@@ -774,7 +792,7 @@ def type_params
   #
   # Net::HTTPHeader#content_type= is an alias for Net::HTTPHeader#set_content_type.
   def set_content_type(type, params = {})
-    @header['content-type'] = [type + params.map{|k,v|"; #{k}=#{v}"}.join('')]
+    @header['content-type'] = [type.to_s + params.map{|k,v|"; #{k}=#{v}"}.join('')]
   end
 
   alias content_type= set_content_type
diff --git a/lib/net/http/response.rb b/lib/net/http/response.rb
index bea4346e..c2424860 100644
--- a/lib/net/http/response.rb
+++ b/lib/net/http/response.rb
@@ -159,7 +159,8 @@ def read_status_line(sock)
       str = sock.readline
       m = /\AHTTP(?:\/(\d+\.\d+))?\s+(\d\d\d)(?:\s+(.*))?\z/in.match(str) or
         raise Net::HTTPBadResponse, "wrong status line: #{str.dump}"
-      m.captures
+      code = m[2] or raise Net::HTTPBadResponse, "wrong status line: #{str.dump}"
+      [m[1], code, m[3]]
     end
 
     def response_class(code)
@@ -169,20 +170,30 @@ def response_class(code)
     end
 
     def each_response_header(sock)
-      key = value = nil
+      key = nil #: String?
+      value = nil #: String?
       while true
         line = sock.readuntil("\n", true).sub(/\s+\z/, '')
         break if line.empty?
-        if line[0] == ?\s or line[0] == ?\t and value
-          value << ' ' unless value.empty?
-          value << line.strip
+        if (line[0] == ?\s || line[0] == ?\t) && value.is_a?(String)
+          current_value = value
+          current_value << ' ' unless current_value.empty?
+          current_value << line.strip
         else
-          yield key, value if key
+          if key.is_a?(String) && value.is_a?(String)
+            current_key = key
+            current_value = value
+            yield current_key, current_value
+          end
           key, value = line.strip.split(/\s*:\s*/, 2)
           raise Net::HTTPBadResponse, 'wrong header line format' if value.nil?
         end
       end
-      yield key, value if key
+      if key.is_a?(String) && value.is_a?(String)
+        current_key = key
+        current_value = value
+        yield current_key, current_value
+      end
     end
   end
 
@@ -274,7 +285,9 @@ def code_type   #:nodoc:
 
   def error!   #:nodoc:
     message = @code
-    message = "#{message} #{@message.dump}" if @message
+    if detail = @message
+      message = "#{message} #{detail.dump}"
+    end
     raise error_type().new(message, self)
   end
 
@@ -369,16 +382,15 @@ def read_body(dest = nil, &block)
     @read = true
     return if @body.nil?
 
-    case enc = @body_encoding
-    when Encoding, false, nil
-      # Encoding: force given encoding
-      # false/nil: do not force encoding
-    else
-      # other value: detect encoding from body
-      enc = detect_encoding(@body)
+    enc = @body_encoding
+    if enc.nil? || enc == false
+      # nil/false: do not force encoding
+    elsif !enc.is_a?(Encoding)
+      body = @body or return
+      enc = detect_encoding(body)
     end
 
-    @body.force_encoding(enc) if enc
+    @body&.force_encoding(enc) if enc
 
     @body
   end
@@ -466,10 +478,10 @@ def scanning_meta(str)
     require 'strscan'
     ss = StringScanner.new(str)
     if ss.scan_until(/<meta[\t\n\f\r ]*/)
-      attrs = {} # attribute_list
+      attrs = {} #: Hash[String, bool] # attribute_list
       got_pragma = false
-      need_pragma = nil
-      charset = nil
+      need_pragma = nil #: bool?
+      charset = nil #: String | Encoding | nil
 
       # step: Attributes
       while attr = get_attribute(ss)
@@ -495,7 +507,13 @@ def scanning_meta(str)
       return if need_pragma.nil?
       return if need_pragma && !got_pragma
 
-      charset = Encoding.find(charset) rescue nil
+      if charset.is_a?(String)
+        begin
+          charset = Encoding.find(charset)
+        rescue ArgumentError
+          charset = nil
+        end
+      end
       return unless charset
       charset = Encoding::UTF_8 if charset == Encoding::UTF_16
       return charset # tentative
@@ -509,7 +527,7 @@ def get_attribute(ss)
       ss.getch
       return nil
     end
-    name = ss.scan(/[^=\t\n\f\r \/>]*/)
+    name = ss.scan(/[^=\t\n\f\r \/>]*/).to_s
     name.downcase!
     raise if name.empty?
     ss.skip(/[\t\n\f\r ]*/)
@@ -521,18 +539,18 @@ def get_attribute(ss)
     case ss.peek(1)
     when '"'
       ss.getch
-      value = ss.scan(/[^"]+/)
+      value = ss.scan(/[^"]+/).to_s
       value.downcase!
       ss.getch
     when "'"
       ss.getch
-      value = ss.scan(/[^']+/)
+      value = ss.scan(/[^']+/).to_s
       value.downcase!
       ss.getch
     when '>'
       value = ''
     else
-      value = ss.scan(/[^\t\n\f\r >]+/)
+      value = ss.scan(/[^\t\n\f\r >]+/).to_s
       value.downcase!
     end
     [name, value]
@@ -556,16 +574,18 @@ def extracting_encodings_from_meta_elements(value)
   # bytes in the range may not be a complete deflate block.
 
   def inflater # :nodoc:
-    return yield @socket unless Net::HTTP::HAVE_ZLIB
-    return yield @socket unless @decode_content
-    return yield @socket if self['content-range']
+    socket = @socket or raise IOError, 'attempt to read body out of block'
+    return yield socket unless Net::HTTP::HAVE_ZLIB
+    return yield socket unless @decode_content
+    return yield socket if self['content-range']
 
     v = self['content-encoding']
     case v&.downcase
     when 'deflate', 'gzip', 'x-gzip' then
       self.delete 'content-encoding'
 
-      inflate_body_io = Inflater.new(@socket)
+      inflate_body_io = Inflater.new(socket)
+      success = false
 
       begin
         yield inflate_body_io
@@ -584,9 +604,9 @@ def inflater # :nodoc:
     when 'none', 'identity' then
       self.delete 'content-encoding'
 
-      yield @socket
+      yield socket
     else
-      yield @socket
+      yield socket
     end
   end
 
@@ -597,19 +617,19 @@ def read_body_0(dest)
         return
       end
 
-      @socket = inflate_body_io
+      body_io = inflate_body_io
 
       clen = content_length()
       if clen
-        @socket.read clen, dest, @ignore_eof
+        body_io.read clen, dest, @ignore_eof
         return
       end
       clen = range_length()
       if clen
-        @socket.read clen, dest
+        body_io.read clen, dest
         return
       end
-      @socket.read_all dest
+      body_io.read_all dest
     end
   end
 
@@ -621,9 +641,10 @@ def read_body_0(dest)
   # See RFC 2616 section 3.6.1 for definitions
 
   def read_chunked(dest, chunk_data_io) # :nodoc:
+    socket = @socket or raise IOError, 'attempt to read body out of block'
     total = 0
     while true
-      line = @socket.readline
+      line = socket.readline
       hexlen = line.slice(/[0-9a-fA-F]+/) or
           raise Net::HTTPBadResponse, "wrong chunk size line: #{line}"
       len = hexlen.hex
@@ -632,16 +653,17 @@ def read_chunked(dest, chunk_data_io) # :nodoc:
         chunk_data_io.read len, dest
       ensure
         total += len
-        @socket.read 2   # \r\n
+        socket.read 2   # \r\n
       end
     end
-    until @socket.readline.empty?
+    until socket.readline.empty?
       # none
     end
   end
 
   def stream_check
-    raise IOError, 'attempt to read body out of block' if @socket.nil? || @socket.closed?
+    socket = @socket or raise IOError, 'attempt to read body out of block'
+    raise IOError, 'attempt to read body out of block' if socket.closed?
   end
 
   def procdest(dest, block)
@@ -736,4 +758,3 @@ def read_all dest
   end
 
 end
-
diff --git a/lib/net/http/status.rb b/lib/net/http/status.rb
index e70b47d9..2e87f770 100644
--- a/lib/net/http/status.rb
+++ b/lib/net/http/status.rb
@@ -11,8 +11,10 @@
   puts
   puts "Net::HTTP::STATUS_CODES = {"
   url = "https://www.iana.org/assignments/http-status-codes/http-status-codes-1.csv"
-  URI(url).read.each_line do |line|
+  uri = URI(url) #: URI::HTTP
+  uri.read({}).each_line do |line|
     code, mes, = line.split(',')
+    next if mes.nil?
     next if ['(Unused)', 'Unassigned', 'Description'].include?(mes)
     puts "  #{code} => '#{mes}',"
   end
diff --git a/net-http.gemspec b/net-http.gemspec
index d59d5c3b..faa08596 100644
--- a/net-http.gemspec
+++ b/net-http.gemspec
@@ -30,7 +30,7 @@ Gem::Specification.new do |spec|
 
   # Specify which files should be added to the gem when it is released.
   # The `git ls-files -z` loads the files in the RubyGem that have been added into git.
-  excludes = %W[/.git* /bin /test /test_sig /*file /#{File.basename(__FILE__)}]
+  excludes = %W[/.git* /bin /test /test_sig /sig/*-impl.rbs /*file /#{File.basename(__FILE__)}]
   spec.files = IO.popen(%W[git -C #{__dir__} ls-files -z --] + excludes.map {|e| ":^#{e}"}, &:read).split("\x0")
   spec.bindir        = "exe"
   spec.require_paths = ["lib"]
diff --git a/sig/net-http-impl.rbs b/sig/net-http-impl.rbs
new file mode 100644
index 00000000..30ae6f17
--- /dev/null
+++ b/sig/net-http-impl.rbs
@@ -0,0 +1,200 @@
+class URI::Generic
+  def authority: () -> String?
+end
+
+module Win32
+  module SSPI
+    class NegotiateAuth
+      def self.new: () -> NegotiateAuth
+      def get_initial_token: () -> String
+      def complete_authentication: (String authphrase) -> String
+    end
+  end
+end
+
+module Net
+  class HTTPAuthenticationError < StandardError
+    def initialize: (String msg, untyped err) -> void
+  end
+
+  module HTTPHeader
+    @header: Hash[String, Array[String]]
+    @body: String?
+    @body_data: Array[untyped] | Hash[untyped, untyped] | nil
+    @body_stream: untyped
+    @form_option: Hash[Symbol, untyped]
+
+    attr_accessor body: String?
+  end
+
+  class HTTP
+    @address: String
+    @port: Integer
+    @ipaddr: String?
+    @local_host: String?
+    @local_port: Integer?
+    @curr_http_version: String
+    @keep_alive_timeout: Float | Integer
+    @last_communicated: Float?
+    @close_on_empty_response: bool
+    @socket: Net::BufferedIO?
+    @started: bool
+    @open_timeout: Float | Integer
+    @read_timeout: Float | Integer
+    @write_timeout: Float | Integer
+    @continue_timeout: Float | Integer | nil
+    @max_retries: Integer
+    @debug_output: IO?
+    @response_body_encoding: Encoding | false | nil
+    @ignore_eof: bool
+    @tcpsocket_supports_open_timeout: bool?
+    @proxy_from_env: bool
+    @proxy_uri: URI::Generic | false | nil
+    @proxy_address: String?
+    @proxy_port: Integer?
+    @proxy_user: String?
+    @proxy_pass: String?
+    @proxy_use_ssl: bool?
+    @use_ssl: bool
+    @ssl_context: OpenSSL::SSL::SSLContext?
+    @ssl_session: OpenSSL::SSL::Session?
+    @sspi_enabled: bool
+    self.@is_proxy_class: bool
+    self.@proxy_from_env: bool
+    self.@proxy_addr: String?
+    self.@proxy_address: String?
+    self.@proxy_port: Integer?
+    self.@proxy_user: String?
+    self.@proxy_pass: String?
+    self.@proxy_use_ssl: bool?
+
+    TCP_SOCKET_NEW_HAS_OPEN_TIMEOUT: bool
+    IDEMPOTENT_METHODS_: Array[String]
+
+    def initialize: (String address, ?Integer? port) -> void
+    def do_start: () -> void
+    def connect: () -> void
+    def timeouted_connect: (String? conn_addr, Integer? conn_port) -> TCPSocket
+    def on_connect: () -> void
+    def do_finish: () -> void
+    def unescape: (String value) -> String
+    def conn_address: () -> String?
+    def conn_port: () -> Integer?
+    def edit_path: (String path) -> String
+    def send_entity: (String | URI::HTTP path, String data, headers? initheader, untyped dest, singleton(Net::HTTPRequest) type) ?{ (String body_segment) -> void } -> Net::HTTPResponse
+    def transport_request: (Net::HTTPGenericRequest req) ?{ (Net::HTTPResponse response) -> void } -> Net::HTTPResponse
+    def begin_transport: (Net::HTTPGenericRequest req) -> void
+    def end_transport: (Net::HTTPGenericRequest req, Net::HTTPResponse res) -> void
+    def keep_alive?: (Net::HTTPGenericRequest req, Net::HTTPResponse res) -> bool
+    def sspi_auth?: (Net::HTTPResponse res) -> bool
+    def sspi_auth: (Net::HTTPGenericRequest req) -> untyped
+    def addr_port: () -> String
+    def debug: (String msg) -> void
+
+    alias D debug
+  end
+
+  class HTTPSession = HTTP
+
+  module HTTP::ProxyDelta
+    def proxy_address: () -> String?
+    def proxy_port: () -> Integer?
+    def use_ssl?: () -> bool
+    def addr_port: () -> String
+    def conn_address: () -> String?
+    def conn_port: () -> Integer?
+    def edit_path: (String path) -> String
+  end
+
+  class HTTPRequest
+    METHOD: String
+    REQUEST_HAS_BODY: bool
+    RESPONSE_HAS_BODY: bool
+  end
+
+  class HTTPGenericRequest
+    @method: String
+    @request_has_body: bool
+    @response_has_body: bool
+    @uri: URI::Generic?
+    @path: String
+    @decode_content: bool
+    @body: String?
+    @body_stream: untyped
+    @body_data: Array[untyped] | Hash[untyped, untyped] | nil
+
+    def set_body_internal: (String? str) -> void
+    def exec: (Net::BufferedIO sock, String ver, String path) -> void
+    def update_uri: (String address, Integer port, bool ssl) -> void
+    def pretty_print: (untyped q) -> void
+    def send_request_with_body: (Net::BufferedIO sock, String ver, String path, String body) -> void
+    def send_request_with_body_stream: (Net::BufferedIO sock, String ver, String path, untyped body_stream) -> void
+    def send_request_with_body_data: (Net::BufferedIO sock, String ver, String path, untyped params) -> void
+    def encode_multipart_form_data: (untyped out, untyped params, untyped opt) -> void
+    def quote_string: (String str, untyped charset) -> String
+    def flush_buffer: (untyped out, String? buf, bool chunked_p) -> untyped
+    def wait_for_continue: (Net::BufferedIO sock, String ver) -> void
+    def write_header: (Net::BufferedIO sock, String ver, String path) -> Integer
+
+    class Chunker
+      @sock: Net::BufferedIO
+
+      def initialize: (Net::BufferedIO sock) -> void
+      def write: (*_ToS buf) -> Integer
+      def finish: () -> Integer
+    end
+  end
+
+  class HTTPResponse
+    @http_version: String?
+    @code: String
+    @message: String?
+    @body: String?
+    @read: bool
+    @uri: URI::Generic?
+    @decode_content: bool
+    @body_encoding: Encoding | false | nil
+    @ignore_eof: bool
+    @socket: Net::BufferedIO?
+    @body_exist: bool
+
+    HAS_BODY: bool
+    EXCEPTION_TYPE: untyped
+    def self.read_new: (Net::BufferedIO sock) -> Net::HTTPResponse
+    def self.exception_type: () -> untyped
+    def self.read_status_line: (Net::BufferedIO sock) -> [String?, String, String?]
+    def self.response_class: (String code) -> singleton(Net::HTTPResponse)
+    def self.each_response_header: (Net::BufferedIO sock) { (String, String) -> void } -> void
+
+    def initialize: (String? httpv, String code, String? msg) -> void
+    def body_encoding=: (Encoding | String | false | nil value) -> (Encoding | false | nil)
+    def ignore_eof=: (bool value) -> bool
+    def response: () -> self
+    def header: () -> self
+    def read_header: () -> self
+    def reading_body: (Net::BufferedIO sock, bool reqmethodallowbody) { () -> untyped } -> String?
+    def detect_encoding: (String str, ?Encoding? encoding) -> Encoding?
+    def sniff_encoding: (String str, ?Encoding? encoding) -> Encoding?
+    def check_bom: (String str) -> Encoding?
+    def scanning_meta: (String str) -> Encoding?
+    def get_attribute: (untyped ss) -> [String, String]?
+    def extracting_encodings_from_meta_elements: (String value) -> String?
+    def inflater: () { (untyped io) -> untyped } -> untyped
+    def read_body_0: (untyped dest) -> void
+    def read_chunked: (untyped dest, untyped chunk_data_io) -> void
+    def stream_check: () -> void
+    def procdest: (untyped dest, untyped block) -> untyped
+
+    class Inflater
+      @socket: Net::BufferedIO
+      @inflate: Zlib::Inflate
+
+      def initialize: (Net::BufferedIO socket) -> void
+      def finish: () -> void
+      def bytes_inflated: () -> Integer
+      def inflate_adapter: (untyped dest) -> Net::ReadAdapter
+      def read: (Integer clen, untyped dest, ?bool ignore_eof) -> untyped
+      def read_all: (untyped dest) -> untyped
+    end
+  end
+end
diff --git a/sig/net-http.rbs b/sig/net-http.rbs
index b54eb936..14279e8d 100644
--- a/sig/net-http.rbs
+++ b/sig/net-http.rbs
@@ -14,9 +14,8 @@ module Net
   #
   # *   [Hypertext Transfer
   #     Protocol](https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol).
-  # *   [Technical
-  #     overview](https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol#Techni
-  #     cal_overview).
+  # *   [Technology](https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol#Tec
+  #     hnology).
   #
   # ## About the Examples
   #
@@ -56,7 +55,7 @@ module Net
   # ## Strategies
   #
   # *   If you will make only a few GET requests, consider using
-  #     [OpenURI](rdoc-ref:OpenURI).
+  #     [OpenURI](https://docs.ruby-lang.org/en/master/OpenURI.html).
   # *   If you will make only a few requests of all kinds, consider using the
   #     various singleton convenience methods in this class. Each of the following
   #     methods automatically starts and finishes a
@@ -83,9 +82,8 @@ module Net
   # *   If performance is important, consider using sessions, which lower request
   #     overhead. This [session](rdoc-ref:Net::HTTP@Sessions) has multiple
   #     requests for [HTTP
-  #     methods](https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol#Request
-  #     _methods) and [WebDAV
-  #     methods](https://en.wikipedia.org/wiki/WebDAV#Implementation):
+  #     methods](https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol#Method)
+  #     and [WebDAV methods](https://en.wikipedia.org/wiki/WebDAV#Implementation):
   #
   #         Net::HTTP.start(hostname) do |http|
   #           # Session started automatically before block execution.
@@ -120,9 +118,9 @@ module Net
   # scheme, hostname, path, query, and fragment; see [URI
   # syntax](https://en.wikipedia.org/wiki/Uniform_Resource_Identifier#Syntax).
   #
-  # A Ruby [URI::Generic](rdoc-ref:URI::Generic) object represents an internet
-  # URI. It provides, among others, methods `scheme`, `hostname`, `path`, `query`,
-  # and `fragment`.
+  # A Ruby [URI::Generic](https://docs.ruby-lang.org/en/master/URI/Generic.html)
+  # object represents an internet URI. It provides, among others, methods
+  # `scheme`, `hostname`, `path`, `query`, and `fragment`.
   #
   # ### Schemes
   #
@@ -212,8 +210,8 @@ module Net
   # single request:
   #
   # *   [HTTP
-  #     methods](https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol#Request
-  #     _methods):
+  #     methods](https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol#Method)
+  #     :
   #
   #     *   #get, #request_get: GET.
   #     *   #head, #request_head: HEAD.
@@ -462,8 +460,8 @@ module Net
   # has header <code>'Content-Range'</code>.
   #
   # Otherwise decompression (or not) depends on the value of header
-  # [Content-Encoding](https://en.wikipedia.org/wiki/List_of_HTTP_header_fields#co
-  # ntent-encoding-response-header):
+  # [Content-Encoding](https://en.wikipedia.org/wiki/List_of_HTTP_header_fields#Co
+  # ntent-Encoding_2):
   #
   # *   <code>'deflate'</code>, <code>'gzip'</code>, or <code>'x-gzip'</code>:
   #     decompresses the body and deletes the header.
@@ -475,7 +473,9 @@ module Net
   #
   # First, what's elsewhere. Class Net::HTTP:
   #
-  # *   Inherits from [class Object](rdoc-ref:Object@What-27s+Here).
+  # *   Inherits from [class
+  #     Object](https://docs.ruby-lang.org/en/master/Object.html#class-object-what
+  #     s-here).
   #
   # This is a categorized summary of methods and attributes.
   #
@@ -761,7 +761,7 @@ module Net
     # -->
     # Like Net::HTTP.get, but writes the returned body to $stdout; returns `nil`.
     #
-    def self.get_print: (URI::Generic uri, ?headers header) -> void
+    def self.get_print: (URI::Generic uri, ?headers? header, ?Integer? port) -> void
                       | (String host, String path, ?Integer port) -> void
 
     # <!--
@@ -797,8 +797,8 @@ module Net
     # *   Net::HTTP::Get: request class for HTTP method `GET`.
     # *   Net::HTTP#get: convenience method for HTTP method `GET`.
     #
-    def self.get: (URI::Generic uri, ?headers header) -> String
-                | (String host, String path, ?Integer port) -> String
+    def self.get: (URI::HTTP uri, ?headers? header, ?Integer? port) -> String?
+                | (String host, String path, ?Integer port) -> String?
 
     # <!--
     #   rdoc-file=lib/net/http.rb
@@ -808,8 +808,9 @@ module Net
     # Like Net::HTTP.get, but returns a Net::HTTPResponse object instead of the body
     # string.
     #
-    def self.get_response: (URI::Generic uri, ?headers header) ?{ (Net::HTTPResponse) -> void } -> Net::HTTPResponse
-                         | (String host, String path, ?Integer port) -> Net::HTTPResponse
+    def self.get_response: (URI::HTTP uri, ?headers? header, ?Integer? port) ?{ (Net::HTTPResponse) -> void } -> Net::HTTPResponse
+                         | (String | URI::HTTP uri_or_host, ?String | headers? path_or_headers, ?Integer? port) ?{ (Net::HTTPResponse) -> void } -> Net::HTTPResponse
+                         | (String host, String path, ?Integer port) ?{ (Net::HTTPResponse) -> void } -> Net::HTTPResponse
 
     # <!--
     #   rdoc-file=lib/net/http.rb
@@ -840,7 +841,7 @@ module Net
     # *   Net::HTTP::Post: request class for HTTP method `POST`.
     # *   Net::HTTP#post: convenience method for HTTP method `POST`.
     #
-    def self.post: (URI::Generic url, String data, ?headers header) -> Net::HTTPResponse
+    def self.post: (URI::HTTP url, String data, ?headers? header) -> Net::HTTPResponse
 
     # <!--
     #   rdoc-file=lib/net/http.rb
@@ -865,7 +866,38 @@ module Net
     #       "id": 101
     #     }
     #
-    def self.post_form: (URI::Generic url, Hash[String, untyped] params) -> Net::HTTPResponse
+    def self.post_form: (URI::HTTP url, Hash[String | Symbol, untyped] params) -> Net::HTTPResponse
+
+    # <!--
+    #   rdoc-file=lib/net/http.rb
+    #   - put(url, data, header = nil)
+    # -->
+    # Sends a PUT request to the server; returns a Net::HTTPResponse object.
+    #
+    # Argument `url` must be a URL; argument `data` must be a string:
+    #
+    #     _uri = uri.dup
+    #     _uri.path = '/posts'
+    #     data = '{"title": "foo", "body": "bar", "userId": 1}'
+    #     headers = {'content-type': 'application/json'}
+    #     res = Net::HTTP.put(_uri, data, headers) # => #<Net::HTTPCreated 201 Created readbody=true>
+    #     puts res.body
+    #
+    # Output:
+    #
+    #     {
+    #       "title": "foo",
+    #       "body": "bar",
+    #       "userId": 1,
+    #       "id": 101
+    #     }
+    #
+    # Related:
+    #
+    # *   Net::HTTP::Put: request class for HTTP method `PUT`.
+    # *   Net::HTTP#put: convenience method for HTTP method `PUT`.
+    #
+    def self.put: (URI::HTTP url, String data, ?headers? header) -> Net::HTTPResponse
 
     # <!--
     #   rdoc-file=lib/net/http.rb
@@ -982,8 +1014,8 @@ module Net
     # Note: If `port` is `nil` and <code>opts[:use_ssl]</code> is a truthy value,
     # the value passed to `new` is Net::HTTP.https_default_port, not `port`.
     #
-    def self.start: (String address, ?Integer? port, ?String | :ENV | nil p_addr, ?Integer? p_port, ?String? p_user, ?String? p_pass, ?Hash[Symbol, untyped]?, **untyped opt) -> Net::HTTP
-                  | [T] (String address, ?Integer? port, ?String | :ENV | nil p_addr, ?Integer? p_port, ?String? p_user, ?String? p_pass, ?Hash[Symbol, untyped]?, **untyped opt) { (Net::HTTP) -> T } -> T
+    def self.start: (String address, *untyped arg) -> Net::HTTP
+                  | [T] (String address, *untyped arg) { (Net::HTTP) -> T } -> T
 
     # <!--
     #   rdoc-file=lib/net/http.rb
@@ -1024,7 +1056,43 @@ module Net
     # For proxy-defining arguments `p_addr` through `p_no_proxy`, see [Proxy
     # Server](rdoc-ref:Net::HTTP@Proxy+Server).
     #
-    def self.new: (String address, ?Integer? port, ?String | :ENV | nil p_addr, ?Integer? p_port, ?String? p_user, ?String? p_pass, ?untyped? p_no_proxy) -> Net::HTTP
+    def self.new: (String address, ?Integer? port, ?String | Symbol | nil p_addr, ?Integer? p_port, ?String? p_user, ?String? p_pass, ?untyped? p_no_proxy, ?bool? p_use_ssl) -> Net::HTTP
+
+    # <!-- rdoc-file=lib/net/http.rb -->
+    # Allows to set the default configuration that will be used when creating a new
+    # connection.
+    #
+    # Example:
+    #
+    #     Net::HTTP.default_configuration = {
+    #       read_timeout: 1,
+    #       write_timeout: 1
+    #     }
+    #     http = Net::HTTP.new(hostname)
+    #     http.open_timeout   # => 60
+    #     http.read_timeout   # => 1
+    #     http.write_timeout  # => 1
+    #
+    def self.default_configuration: () -> Hash[Symbol, untyped]?
+
+    # <!-- rdoc-file=lib/net/http.rb -->
+    # Allows to set the default configuration that will be used when creating a new
+    # connection.
+    #
+    # Example:
+    #
+    #     Net::HTTP.default_configuration = {
+    #       read_timeout: 1,
+    #       write_timeout: 1
+    #     }
+    #     http = Net::HTTP.new(hostname)
+    #     http.open_timeout   # => 60
+    #     http.read_timeout   # => 1
+    #     http.write_timeout  # => 1
+    #
+    def self.default_configuration=: (Hash[Symbol, untyped]?) -> Hash[Symbol, untyped]?
+
+    def self.socket_type: () -> singleton(Net::BufferedIO)
 
     # <!--
     #   rdoc-file=lib/net/http.rb
@@ -1106,18 +1174,18 @@ module Net
     # Sets or returns the string local host used to establish the connection;
     # initially `nil`.
     #
-    attr_accessor local_host: String
+    attr_accessor local_host: String?
 
     # <!-- rdoc-file=lib/net/http.rb -->
     # Sets or returns the integer local port used to establish the connection;
     # initially `nil`.
     #
-    attr_accessor local_port: Integer
+    attr_accessor local_port: Integer?
 
     # <!-- rdoc-file=lib/net/http.rb -->
     # Sets whether to determine the proxy from environment variable
     # '<code>ENV['http_proxy']</code>'; see {Proxy Using
-    # [ENV]('http_proxy')}[Net::HTTP@Proxy+Using+-27ENV-5B-27http_proxy-27-5D-27].
+    # [ENV]('http_proxy')}[Net::HTTP@Proxy+Using+ENVHTTPProxy].
     #
     attr_writer proxy_from_env: untyped
 
@@ -1141,6 +1209,12 @@ module Net
     #
     attr_accessor proxy_pass: String?
 
+    # <!-- rdoc-file=lib/net/http.rb -->
+    # Sets whether the proxy uses SSL; see [Proxy
+    # Server](rdoc-ref:Net::HTTP@Proxy+Server).
+    #
+    attr_writer proxy_use_ssl: bool?
+
     # <!--
     #   rdoc-file=lib/net/http.rb
     #   - ipaddr()
@@ -1267,6 +1341,35 @@ module Net
     #
     attr_accessor continue_timeout: Float | Integer | nil
 
+    # <!-- rdoc-file=lib/net/http.rb -->
+    # Returns the encoding to use for the response body; see
+    # #response_body_encoding=.
+    #
+    def response_body_encoding: () -> (Encoding | String | false | nil)
+
+    # <!--
+    #   rdoc-file=lib/net/http.rb
+    #   - response_body_encoding=(value)
+    # -->
+    # Sets the encoding to be used for the response body; returns the encoding.
+    #
+    # The given `value` may be:
+    #
+    # *   An Encoding object.
+    # *   The name of an encoding.
+    # *   An alias for an encoding name.
+    #
+    # See [Encoding](https://docs.ruby-lang.org/en/master/Encoding.html).
+    #
+    # Examples:
+    #
+    #     http = Net::HTTP.new(hostname)
+    #     http.response_body_encoding = Encoding::US_ASCII # => #<Encoding:US-ASCII>
+    #     http.response_body_encoding = 'US-ASCII'         # => "US-ASCII"
+    #     http.response_body_encoding = 'ASCII'            # => "ASCII"
+    #
+    def response_body_encoding=: (Encoding | String | false | nil) -> (Encoding | String | false | nil)
+
     # <!-- rdoc-file=lib/net/http.rb -->
     # Sets or returns the numeric (Integer or Float) number of seconds to keep the
     # connection open after a request is sent; initially 2. If a new request is made
@@ -1487,7 +1590,7 @@ module Net
     # This class is obsolete.  You may pass these same parameters directly to
     # Net::HTTP.new.  See Net::HTTP.new for details of the arguments.
     #
-    def self.Proxy: (?interned p_addr, ?Integer? p_port, ?String? p_user, ?String? p_pass) -> untyped
+    def self.Proxy: (?interned p_addr, ?Integer? p_port, ?String? p_user, ?String? p_pass, ?bool? p_use_ssl) -> untyped
 
     # <!--
     #   rdoc-file=lib/net/http.rb
@@ -1585,7 +1688,7 @@ module Net
     # *   Net::HTTP::Get: request class for HTTP method GET.
     # *   Net::HTTP.get: sends GET request, returns response body.
     #
-    def get: (String path, ?headers initheader, ?bot dest) ?{ (String body_segment) -> void } -> Net::HTTPResponse
+    def get: (String path, ?headers? initheader, ?untyped dest) ?{ (String body_segment) -> void } -> Net::HTTPResponse
 
     # <!--
     #   rdoc-file=lib/net/http.rb
@@ -1605,7 +1708,7 @@ module Net
     #      ["content-type", ["application/json; charset=utf-8"]],
     #      ["connection", ["close"]]]
     #
-    def head: (String path, ?headers initheader) -> Net::HTTPResponse
+    def head: (String path, ?headers? initheader) -> Net::HTTPResponse
 
     # <!--
     #   rdoc-file=lib/net/http.rb
@@ -1638,7 +1741,7 @@ module Net
     # *   Net::HTTP::Post: request class for HTTP method POST.
     # *   Net::HTTP.post: sends POST request, returns response body.
     #
-    def post: (String path, String data, ?headers initheader, ?bot dest) ?{ (String body_segment) -> void } -> Net::HTTPResponse
+    def post: (String | URI::HTTP path, String data, ?headers? initheader, ?untyped dest) ?{ (String body_segment) -> void } -> Net::HTTPResponse
 
     # <!--
     #   rdoc-file=lib/net/http.rb
@@ -1666,7 +1769,7 @@ module Net
     #
     #     http.patch('/todos/1', data) # => #<Net::HTTPCreated 201 Created readbody=true>
     #
-    def patch: (String path, String data, ?headers initheader, ?bot dest) ?{ (String body_segment) -> void } -> Net::HTTPResponse
+    def patch: (String path, String data, ?headers? initheader, ?untyped dest) ?{ (String body_segment) -> void } -> Net::HTTPResponse
 
     # <!--
     #   rdoc-file=lib/net/http.rb
@@ -1687,7 +1790,7 @@ module Net
     # *   Net::HTTP::Put: request class for HTTP method PUT.
     # *   Net::HTTP.put: sends PUT request, returns response body.
     #
-    def put: (String path, String data, ?headers initheader) -> Net::HTTPResponse
+    def put: (String | URI::HTTP path, String data, ?headers? initheader) -> Net::HTTPResponse
 
     # <!--
     #   rdoc-file=lib/net/http.rb
@@ -1703,7 +1806,7 @@ module Net
     #     http = Net::HTTP.new(hostname)
     #     http.proppatch('/todos/1', data)
     #
-    def proppatch: (String path, String body, ?headers initheader) -> Net::HTTPResponse
+    def proppatch: (String path, String body, ?headers? initheader) -> Net::HTTPResponse
 
     # <!--
     #   rdoc-file=lib/net/http.rb
@@ -1719,7 +1822,7 @@ module Net
     #     http = Net::HTTP.new(hostname)
     #     http.lock('/todos/1', data)
     #
-    def lock: (String path, String body, ?headers initheader) -> Net::HTTPResponse
+    def lock: (String path, String body, ?headers? initheader) -> Net::HTTPResponse
 
     # <!--
     #   rdoc-file=lib/net/http.rb
@@ -1735,7 +1838,7 @@ module Net
     #     http = Net::HTTP.new(hostname)
     #     http.unlock('/todos/1', data)
     #
-    def unlock: (String path, String body, ?headers initheader) -> Net::HTTPResponse
+    def unlock: (String path, String body, ?headers? initheader) -> Net::HTTPResponse
 
     # <!--
     #   rdoc-file=lib/net/http.rb
@@ -1750,7 +1853,7 @@ module Net
     #     http = Net::HTTP.new(hostname)
     #     http.options('/')
     #
-    def options: (String path, ?headers initheader) -> Net::HTTPResponse
+    def options: (String path, ?headers? initheader) -> Net::HTTPResponse
 
     # <!--
     #   rdoc-file=lib/net/http.rb
@@ -1766,7 +1869,7 @@ module Net
     #     http = Net::HTTP.new(hostname)
     #     http.propfind('/todos/1', data)
     #
-    def propfind: (String path, ?untyped? body, ?headers initheader) -> Net::HTTPResponse
+    def propfind: (String path, ?untyped? body, ?headers? initheader) -> Net::HTTPResponse
 
     # <!--
     #   rdoc-file=lib/net/http.rb
@@ -1781,7 +1884,7 @@ module Net
     #     http = Net::HTTP.new(hostname)
     #     http.delete('/todos/1')
     #
-    def delete: (String path, ?headers initheader) -> Net::HTTPResponse
+    def delete: (String path, ?headers? initheader) -> Net::HTTPResponse
 
     # <!--
     #   rdoc-file=lib/net/http.rb
@@ -1796,7 +1899,7 @@ module Net
     #     http = Net::HTTP.new(hostname)
     #     http.move('/todos/1')
     #
-    def move: (String path, ?headers initheader) -> Net::HTTPResponse
+    def move: (String path, ?headers? initheader) -> Net::HTTPResponse
 
     # <!--
     #   rdoc-file=lib/net/http.rb
@@ -1811,7 +1914,7 @@ module Net
     #     http = Net::HTTP.new(hostname)
     #     http.copy('/todos/1')
     #
-    def copy: (String path, ?headers initheader) -> Net::HTTPResponse
+    def copy: (String path, ?headers? initheader) -> Net::HTTPResponse
 
     # <!--
     #   rdoc-file=lib/net/http.rb
@@ -1827,7 +1930,7 @@ module Net
     #     http.mkcol('/todos/1', data)
     #     http = Net::HTTP.new(hostname)
     #
-    def mkcol: (String path, ?untyped? body, ?headers initheader) -> Net::HTTPResponse
+    def mkcol: (String path, ?untyped? body, ?headers? initheader) -> Net::HTTPResponse
 
     # <!--
     #   rdoc-file=lib/net/http.rb
@@ -1842,7 +1945,7 @@ module Net
     #     http = Net::HTTP.new(hostname)
     #     http.trace('/todos/1')
     #
-    def trace: (String path, ?headers initheader) -> Net::HTTPResponse
+    def trace: (String path, ?headers? initheader) -> Net::HTTPResponse
 
     # <!--
     #   rdoc-file=lib/net/http.rb
@@ -1870,7 +1973,7 @@ module Net
     #
     #     #<Net::HTTPOK 200 OK readbody=false>
     #
-    def request_get: (String path, ?headers initheader) ?{ (Net::HTTPResponse response) -> void } -> Net::HTTPResponse
+    def request_get: (String | URI::HTTP path, ?headers? initheader) ?{ (Net::HTTPResponse response) -> void } -> Net::HTTPResponse
 
     # <!--
     #   rdoc-file=lib/net/http.rb
@@ -1885,7 +1988,7 @@ module Net
     #     http = Net::HTTP.new(hostname)
     #     http.head('/todos/1') # => #<Net::HTTPOK 200 OK readbody=true>
     #
-    def request_head: (String path, ?headers initheader) ?{ (Net::HTTPResponse response) -> void } -> Net::HTTPResponse
+    def request_head: (String path, ?headers? initheader) ?{ (Net::HTTPResponse response) -> void } -> Net::HTTPResponse
 
     # <!--
     #   rdoc-file=lib/net/http.rb
@@ -1914,9 +2017,9 @@ module Net
     #
     #     "{\n  \"xyzzy\": \"\",\n  \"id\": 201\n}"
     #
-    def request_post: (String path, String data, ?headers initheader) ?{ (Net::HTTPResponse response) -> void } -> Net::HTTPResponse
+    def request_post: (String path, String data, ?headers? initheader) ?{ (Net::HTTPResponse response) -> void } -> Net::HTTPResponse
 
-    def request_put: (String path, String data, ?headers initheader) ?{ (Net::HTTPResponse response) -> void } -> Net::HTTPResponse
+    def request_put: (String path, String data, ?headers? initheader) ?{ (Net::HTTPResponse response) -> void } -> Net::HTTPResponse
 
     # <!--
     #   rdoc-file=lib/net/http.rb
@@ -2001,7 +2104,7 @@ module Net
     #
     #     #<Net::HTTPOK 200 OK readbody=false>
     #
-    def request: (Net::HTTPRequest req, ?String? body) ?{ (Net::HTTPResponse response) -> void } -> Net::HTTPResponse
+    def request: (Net::HTTPGenericRequest req, ?String? body) ?{ (Net::HTTPResponse response) -> void } -> Net::HTTPResponse
   end
 
   # <!-- rdoc-file=lib/net/http/generic_request.rb -->
@@ -2052,7 +2155,7 @@ module Net
     #   - new(m, reqbody, resbody, uri_or_path, initheader = nil)
     # -->
     #
-    def initialize: (String m, boolish reqbody, boolish resbody, URI::Generic | String uri_or_path, ?headers initheader) -> void
+    def initialize: (String m, boolish reqbody, boolish resbody, URI::HTTP | String uri_or_path, ?headers? initheader) -> void
 
     # <!-- rdoc-file=lib/net/http/generic_request.rb -->
     # Returns the string method name for the request:
@@ -2077,7 +2180,7 @@ module Net
     #     # => #<URI::HTTPS https://jsonplaceholder.typicode.com/>
     #     Net::HTTP::Get.new('example.com').uri # => nil
     #
-    attr_reader uri: URI::Generic
+    attr_reader uri: URI::Generic?
 
     # <!-- rdoc-file=lib/net/http/generic_request.rb -->
     # Returns `false` if the request's header <code>'Accept-Encoding'</code> has
@@ -2406,12 +2509,22 @@ module Net
   # *   #each_value: Passes each string field value to the block.
   #
   module HTTPHeader : BasicObject
+    # <!-- rdoc-file=lib/net/http/header.rb -->
+    # The maximum length of HTTP header keys.
+    #
+    MAX_KEY_LENGTH: Integer
+
+    # <!-- rdoc-file=lib/net/http/header.rb -->
+    # The maximum length of HTTP header values.
+    #
+    MAX_FIELD_LENGTH: Integer
+
     # <!--
     #   rdoc-file=lib/net/http/header.rb
     #   - initialize_http_header(initheader)
     # -->
     #
-    def initialize_http_header: (Hash[untyped, untyped] initheader) -> void
+    def initialize_http_header: (Hash[untyped, untyped]? initheader) -> void
 
     def size: () -> Integer
 
@@ -2533,9 +2646,8 @@ module Net
     #     res.fetch('Nosuch', 'Foo')     # => "Foo"
     #     res.fetch('Nosuch')            # Raises KeyError.
     #
-    def fetch: (interned key) -> String
-             | (interned key, untyped) -> untyped
-             | (interned key) { (String) -> untyped } -> untyped
+    def fetch: (interned key, *untyped args) -> untyped
+             | (interned key, *untyped args) { (String) -> untyped } -> untyped
 
     # <!--
     #   rdoc-file=lib/net/http/header.rb
@@ -2623,7 +2735,7 @@ module Net
     #     "Cf-Ray"
     #
     # The capitalization is system-dependent; see [Case
-    # Mapping](rdoc-ref:case_mapping.rdoc).
+    # Mapping](https://docs.ruby-lang.org/en/master/case_mapping_rdoc.html).
     #
     # Returns an enumerator if no block is given.
     #
@@ -2664,7 +2776,7 @@ module Net
     #     req.delete('Accept') # => ["*/*"]
     #     req.delete('Nosuch') # => nil
     #
-    def delete: (interned key) -> (Array[String] | nil)
+    def delete: (String | Symbol key) -> (Array[String] | nil)
 
     # <!--
     #   rdoc-file=lib/net/http/header.rb
@@ -2677,7 +2789,7 @@ module Net
     #     req.key?('Accept') # => true
     #     req.key?('Nosuch') # => false
     #
-    def key?: (interned key) -> bool
+    def key?: (String | Symbol key) -> bool
 
     # <!--
     #   rdoc-file=lib/net/http/header.rb
@@ -2721,7 +2833,7 @@ module Net
     #   - capitalize(name)
     # -->
     #
-    def capitalize: (interned name) -> String
+    def capitalize: (String | Symbol name) -> String
 
     public
 
@@ -2770,7 +2882,7 @@ module Net
     #
     # Net::HTTPHeader#range= is an alias for Net::HTTPHeader#set_range.
     #
-    def set_range: (Range[Integer] | Numeric r, ?Integer? e) -> Range[Integer]
+    def set_range: (Range[Integer] | Numeric? r, ?Integer? e) -> (Range[Integer] | Numeric | nil)
 
     # <!--
     #   rdoc-file=lib/net/http/header.rb
@@ -2948,7 +3060,7 @@ module Net
     # Net::HTTPHeader#content_type= is an alias for
     # Net::HTTPHeader#set_content_type.
     #
-    def set_content_type: (interned `type`, ?Hash[untyped, untyped] params) -> void
+    def set_content_type: (String | Symbol `type`, ?Hash[untyped, untyped] params) -> void
 
     # <!--
     #   rdoc-file=lib/net/http/header.rb
@@ -2968,7 +3080,8 @@ module Net
     # The resulting request is suitable for HTTP request `POST` or `PUT`.
     #
     # Argument `params` must be suitable for use as argument `enum` to
-    # [URI.encode_www_form](rdoc-ref:URI.encode_www_form).
+    # [URI.encode_www_form](https://docs.ruby-lang.org/en/master/URI.html#method-c-e
+    # ncode_www_form).
     #
     # With only argument `params` given, sets the body to a URL-encoded string with
     # the default separator <code>'&'</code>:
@@ -3018,8 +3131,9 @@ module Net
     # *   An IO stream opened for reading.
     #
     # Argument `params` should be an
-    # [Enumerable](rdoc-ref:Enumerable@Enumerable+in+Ruby+Classes) (method
-    # <code>params.map</code> will be called), and is often an array or hash.
+    # [Enumerable](https://docs.ruby-lang.org/en/master/Enumerable.html#module-Enume
+    # rable-label-Enumerable+in+Ruby+Classes) (method <code>params.map</code> will
+    # be called), and is often an array or hash.
     #
     # First, we set up a request:
     #
@@ -3255,8 +3369,7 @@ module Net
     # to enable compression of the response body unless Accept-Encoding or Range are
     # supplied in `initheader`.
     #
-    def initialize: (String path, ?headers initheader) -> void
-                  | (URI::Generic uri, ?headers initheader) -> void
+    def initialize: (String | URI::HTTP path, ?headers? initheader) -> void
   end
 
   # <!-- rdoc-file=lib/net/http/requests.rb -->
@@ -3278,12 +3391,9 @@ module Net
   #
   # *   Request body: optional.
   # *   Response body: yes.
-  # *   [Safe](https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol#Safe_meth
-  #     ods): yes.
-  # *   [Idempotent](https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol#Ide
-  #     mpotent_methods): yes.
-  # *   [Cacheable](https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol#Cach
-  #     eable_methods): yes.
+  # *   [Safe](https://en.wikipedia.org/wiki/HTTP#Safe_method): yes.
+  # *   [Idempotent](https://en.wikipedia.org/wiki/HTTP#Idempotent_method): yes.
+  # *   [Cacheable](https://en.wikipedia.org/wiki/HTTP#Cacheable_method): yes.
   #
   # Related:
   #
@@ -3317,12 +3427,9 @@ module Net
   #
   # *   Request body: optional.
   # *   Response body: no.
-  # *   [Safe](https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol#Safe_meth
-  #     ods): yes.
-  # *   [Idempotent](https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol#Ide
-  #     mpotent_methods): yes.
-  # *   [Cacheable](https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol#Cach
-  #     eable_methods): yes.
+  # *   [Safe](https://en.wikipedia.org/wiki/HTTP#Safe_method): yes.
+  # *   [Idempotent](https://en.wikipedia.org/wiki/HTTP#Idempotent_method): yes.
+  # *   [Cacheable](https://en.wikipedia.org/wiki/HTTP#Cacheable_method): yes.
   #
   # Related:
   #
@@ -3358,12 +3465,9 @@ module Net
   #
   # *   Request body: yes.
   # *   Response body: yes.
-  # *   [Safe](https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol#Safe_meth
-  #     ods): no.
-  # *   [Idempotent](https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol#Ide
-  #     mpotent_methods): no.
-  # *   [Cacheable](https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol#Cach
-  #     eable_methods): yes.
+  # *   [Safe](https://en.wikipedia.org/wiki/HTTP#Safe_method): no.
+  # *   [Idempotent](https://en.wikipedia.org/wiki/HTTP#Idempotent_method): no.
+  # *   [Cacheable](https://en.wikipedia.org/wiki/HTTP#Cacheable_method): yes.
   #
   # Related:
   #
@@ -3400,12 +3504,9 @@ module Net
   #
   # *   Request body: yes.
   # *   Response body: yes.
-  # *   [Safe](https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol#Safe_meth
-  #     ods): no.
-  # *   [Idempotent](https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol#Ide
-  #     mpotent_methods): yes.
-  # *   [Cacheable](https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol#Cach
-  #     eable_methods): no.
+  # *   [Safe](https://en.wikipedia.org/wiki/HTTP#Safe_method): no.
+  # *   [Idempotent](https://en.wikipedia.org/wiki/HTTP#Idempotent_method): yes.
+  # *   [Cacheable](https://en.wikipedia.org/wiki/HTTP#Cacheable_method): no.
   #
   # Related:
   #
@@ -3440,12 +3541,9 @@ module Net
   #
   # *   Request body: optional.
   # *   Response body: yes.
-  # *   [Safe](https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol#Safe_meth
-  #     ods): no.
-  # *   [Idempotent](https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol#Ide
-  #     mpotent_methods): yes.
-  # *   [Cacheable](https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol#Cach
-  #     eable_methods): no.
+  # *   [Safe](https://en.wikipedia.org/wiki/HTTP#Safe_method): no.
+  # *   [Idempotent](https://en.wikipedia.org/wiki/HTTP#Idempotent_method): yes.
+  # *   [Cacheable](https://en.wikipedia.org/wiki/HTTP#Cacheable_method): no.
   #
   # Related:
   #
@@ -3478,12 +3576,9 @@ module Net
   #
   # *   Request body: optional.
   # *   Response body: yes.
-  # *   [Safe](https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol#Safe_meth
-  #     ods): yes.
-  # *   [Idempotent](https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol#Ide
-  #     mpotent_methods): yes.
-  # *   [Cacheable](https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol#Cach
-  #     eable_methods): no.
+  # *   [Safe](https://en.wikipedia.org/wiki/HTTP#Safe_method): yes.
+  # *   [Idempotent](https://en.wikipedia.org/wiki/HTTP#Idempotent_method): yes.
+  # *   [Cacheable](https://en.wikipedia.org/wiki/HTTP#Cacheable_method): no.
   #
   # Related:
   #
@@ -3516,12 +3611,9 @@ module Net
   #
   # *   Request body: no.
   # *   Response body: yes.
-  # *   [Safe](https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol#Safe_meth
-  #     ods): yes.
-  # *   [Idempotent](https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol#Ide
-  #     mpotent_methods): yes.
-  # *   [Cacheable](https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol#Cach
-  #     eable_methods): no.
+  # *   [Safe](https://en.wikipedia.org/wiki/HTTP#Safe_method): yes.
+  # *   [Idempotent](https://en.wikipedia.org/wiki/HTTP#Idempotent_method): yes.
+  # *   [Cacheable](https://en.wikipedia.org/wiki/HTTP#Cacheable_method): no.
   #
   # Related:
   #
@@ -3557,12 +3649,9 @@ module Net
   #
   # *   Request body: yes.
   # *   Response body: yes.
-  # *   [Safe](https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol#Safe_meth
-  #     ods): no.
-  # *   [Idempotent](https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol#Ide
-  #     mpotent_methods): no.
-  # *   [Cacheable](https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol#Cach
-  #     eable_methods): no.
+  # *   [Safe](https://en.wikipedia.org/wiki/HTTP#Safe_method): no.
+  # *   [Idempotent](https://en.wikipedia.org/wiki/HTTP#Idempotent_method): no.
+  # *   [Cacheable](https://en.wikipedia.org/wiki/HTTP#Cacheable_method): no.
   #
   # Related:
   #
@@ -3936,7 +4025,7 @@ module Net
     # <!-- rdoc-file=lib/net/http/response.rb -->
     # The HTTP version supported by the server.
     #
-    attr_reader http_version: String
+    attr_reader http_version: String?
 
     # <!-- rdoc-file=lib/net/http/response.rb -->
     # The HTTP result code string. For example, '302'.  You can also determine the
@@ -3948,7 +4037,7 @@ module Net
     # <!-- rdoc-file=lib/net/http/response.rb -->
     # The HTTP result message sent by the server. For example, 'Not Found'.
     #
-    attr_reader message: String
+    attr_reader message: String?
 
     # <!-- rdoc-file=lib/net/http/response.rb -->
     # The HTTP result message sent by the server. For example, 'Not Found'.
@@ -3978,7 +4067,7 @@ module Net
 
     def error!: () -> untyped
 
-    def error_type: () -> (Net::HTTPError | Net::HTTPServerException | Net::HTTPRetriableError | Net::HTTPFatalError)
+    def error_type: () -> (singleton(Net::HTTPError) | singleton(Net::HTTPClientException) | singleton(Net::HTTPRetriableError) | singleton(Net::HTTPFatalError))
 
     # <!--
     #   rdoc-file=lib/net/http/response.rb
@@ -3988,7 +4077,7 @@ module Net
     #
     def value: () -> (nil | untyped)
 
-    def uri=: (URI::Generic uri) -> void
+    def uri=: (URI::Generic? uri) -> void
 
     interface _Dest
       def <<: (String) -> void
@@ -4026,9 +4115,9 @@ module Net
     #       end
     #     }
     #
-    def read_body: () -> String
-                 | (_Dest dest) -> String
-                 | () { (String) -> void } -> String
+    def read_body: () -> String?
+                 | (_Dest dest) -> String?
+                 | () { (String) -> void } -> String?
 
     # <!--
     #   rdoc-file=lib/net/http/response.rb
@@ -4049,7 +4138,7 @@ module Net
     #     "{\n  \"userId\": 1,\n  \"id\": 1,\n  \"title\": \"delectus aut autem\",\n  \"completed\": false\n}"
     #     nil
     #
-    def body: () -> String
+    def body: () -> String?
 
     # <!--
     #   rdoc-file=lib/net/http/response.rb
@@ -4073,7 +4162,7 @@ module Net
   class HTTPUnknownResponse < HTTPResponse
     HAS_BODY: bool
 
-    EXCEPTION_TYPE: Net::HTTPError
+    EXCEPTION_TYPE: singleton(Net::HTTPError)
   end
 
   # <!-- rdoc-file=lib/net/http/responses.rb -->
@@ -4091,7 +4180,7 @@ module Net
   class HTTPInformation < HTTPResponse
     HAS_BODY: bool
 
-    EXCEPTION_TYPE: Net::HTTPError
+    EXCEPTION_TYPE: singleton(Net::HTTPError)
   end
 
   # <!-- rdoc-file=lib/net/http/responses.rb -->
@@ -4109,7 +4198,7 @@ module Net
   class HTTPSuccess < HTTPResponse
     HAS_BODY: bool
 
-    EXCEPTION_TYPE: Net::HTTPError
+    EXCEPTION_TYPE: singleton(Net::HTTPError)
   end
 
   # <!-- rdoc-file=lib/net/http/responses.rb -->
@@ -4127,7 +4216,7 @@ module Net
   class HTTPRedirection < HTTPResponse
     HAS_BODY: bool
 
-    EXCEPTION_TYPE: Net::HTTPRetriableError
+    EXCEPTION_TYPE: singleton(Net::HTTPRetriableError)
   end
 
   # <!-- rdoc-file=lib/net/http/responses.rb -->
@@ -4144,7 +4233,7 @@ module Net
   class HTTPClientError < HTTPResponse
     HAS_BODY: bool
 
-    EXCEPTION_TYPE: untyped
+    EXCEPTION_TYPE: singleton(Net::HTTPClientException)
   end
 
   # <!-- rdoc-file=lib/net/http/responses.rb -->
@@ -4161,7 +4250,7 @@ module Net
   class HTTPServerError < HTTPResponse
     HAS_BODY: bool
 
-    EXCEPTION_TYPE: Net::HTTPFatalError
+    EXCEPTION_TYPE: singleton(Net::HTTPFatalError)
   end
 
   # <!-- rdoc-file=lib/net/http/responses.rb -->
@@ -4483,7 +4572,7 @@ module Net
   #     s).
   # *   [Wikipedia](https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#300).
   #
-  HTTPMultipleChoice: HTTPMultipleChoices
+  class HTTPMultipleChoice = HTTPMultipleChoices
 
   # <!-- rdoc-file=lib/net/http/responses.rb -->
   # Response class for `Moved Permanently` responses (status code 301).
@@ -5549,6 +5638,20 @@ module Net
 
   HTTP::STATUS_CODES: Hash[Integer, String]
 
+  class HTTPMovedTemporarily = HTTPFound
+
+  class HTTPRequestTimeOut = HTTPRequestTimeout
+
+  class HTTPRequestEntityTooLarge = HTTPPayloadTooLarge
+
+  class HTTPRequestURITooLong = HTTPURITooLong
+
+  class HTTPRequestURITooLarge = HTTPRequestURITooLong
+
+  class HTTPRequestedRangeNotSatisfiable = HTTPRangeNotSatisfiable
+
+  class HTTPGatewayTimeOut = HTTPGatewayTimeout
+
   # <!-- rdoc-file=lib/net/http/exceptions.rb -->
   # Net::HTTP exception class. You cannot use Net::HTTPExceptions directly;
   # instead, you must use its subclasses.
@@ -5569,11 +5672,13 @@ module Net
     include Net::HTTPExceptions
   end
 
-  class HTTPServerException < ProtoServerError
+  class HTTPClientException < ProtoServerError
     # We cannot use the name "HTTPServerError", it is the name of the response.
     include Net::HTTPExceptions
   end
 
+  class HTTPServerException = HTTPClientException
+
   class HTTPFatalError < ProtoFatalError
     include Net::HTTPExceptions
   end
diff --git a/sig/net-protocol-impl.rbs b/sig/net-protocol-impl.rbs
new file mode 100644
index 00000000..5bdb4081
--- /dev/null
+++ b/sig/net-protocol-impl.rbs
@@ -0,0 +1,94 @@
+module Net
+  class Protocol
+    private
+
+    def ssl_socket_connect: (untyped socket, Time::_Timeout? timeout) -> void
+  end
+
+  class ProtocolError < StandardError
+  end
+
+  class ProtoSyntaxError < ProtocolError
+  end
+
+  class ProtoFatalError < ProtocolError
+  end
+
+  class ProtoUnknownError < ProtocolError
+  end
+
+  class ProtoServerError < ProtocolError
+  end
+
+  class ProtoAuthError < ProtocolError
+  end
+
+  class ProtoCommandError < ProtocolError
+  end
+
+  class ProtoRetriableError < ProtocolError
+  end
+
+  class OpenTimeout < Timeout::Error
+  end
+
+  class ReadTimeout < Timeout::Error
+    attr_reader io: IO?
+
+    def initialize: (?IO? io) -> void
+    def message: () -> String
+  end
+
+  class WriteTimeout < Timeout::Error
+    attr_reader io: IO?
+
+    def initialize: (?IO? io) -> void
+    def message: () -> String
+  end
+
+  class BufferedIO
+    def initialize: (
+      untyped io,
+      ?read_timeout: Time::_Timeout,
+      ?write_timeout: Time::_Timeout,
+      ?continue_timeout: Time::_Timeout?,
+      ?debug_output: IO?
+    ) -> void
+
+    attr_reader io: untyped
+    attr_accessor read_timeout: Time::_Timeout
+    attr_accessor write_timeout: Time::_Timeout
+    attr_accessor continue_timeout: Time::_Timeout?
+    attr_accessor debug_output: IO?
+
+    def inspect: () -> String
+    def eof?: () -> bool
+    def closed?: () -> bool
+    def close: () -> untyped
+    def read: (Integer len, ?untyped dest, ?bool ignore_eof) -> untyped
+    def read_all: (?untyped dest) -> untyped
+    def readuntil: (String terminator, ?bool ignore_eof) -> String
+    def readline: () -> String
+    def write: (*_ToS strs) -> Integer
+    def <<: (*_ToS strs) -> Integer
+    def writeline: (String str) -> Integer
+  end
+
+  class ReadAdapter
+    def initialize: (Proc block) -> void
+    def inspect: () -> String
+    def <<: (String str) -> untyped
+  end
+
+end
+
+class TCPSocket
+  def self.new: (
+    String remote_host,
+    Integer remote_port,
+    ?String? local_host,
+    ?Integer? local_port,
+    ?fast_fallback: boolish,
+    ?open_timeout: Time::_Timeout
+  ) -> instance
+end