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agent, apps, examples: relay whole agent messages #1262

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0975303
agent, apps, examples: relay whole agent messages
yosuke-wolfssl Sep 18, 2026
6532128
agent: raise the message size ceiling
yosuke-wolfssl Sep 18, 2026
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95 changes: 60 additions & 35 deletions apps/wolfssh/wolfssh.c
View file
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Original file line number Diff line number Diff line change
Expand Up @@ -263,13 +263,6 @@ static void modes_reset(void)

#ifndef WOLFSSL_NUCLEUS

#if defined(WOLFSSH_AGENT)
static inline void ato32(const byte* c, word32* u32)
{
*u32 = (c[0] << 24) | (c[1] << 16) | (c[2] << 8) | c[3];
}
#endif

typedef struct thread_args {
WOLFSSH* ssh;
wolfSSL_Mutex lock;
Expand Down Expand Up @@ -582,6 +575,18 @@ static THREAD_RET readInput(void* in)
}


#ifdef WOLFSSH_AGENT
/* Statuses that say the relay still owes a reply rather than failing. */
static int AgentRelayHeld(int code, int* wantsWrite)
{
*wantsWrite = (code == WS_WANT_WRITE);
return code == WS_WANT_WRITE || code == WS_WINDOW_FULL
|| code == WS_REKEYING;
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}


#endif

static THREAD_RET readPeer(void* in)
{
byte buf[256];
Expand All @@ -595,8 +600,14 @@ static THREAD_RET readPeer(void* in)
HANDLE stdoutHandle = GetStdHandle(STD_OUTPUT_HANDLE);
#endif
fd_set readSet;
fd_set writeSet;
fd_set errSet;
struct timeval timeout;
#ifdef WOLFSSH_AGENT
word32 agentChannel = 0;
int agentOwed = 0;
int agentWantsWrite = 0;
#endif

#ifdef USE_WINDOWS_API
if (args->rawMode == 0) {
Expand Down Expand Up @@ -630,13 +641,19 @@ static THREAD_RET readPeer(void* in)
(void)windowMonitor(args);
#endif
FD_ZERO(&readSet);
FD_ZERO(&writeSet);
FD_ZERO(&errSet);
FD_SET(fd, &readSet);
FD_SET(fd, &errSet);

#ifdef WOLFSSH_AGENT
if (agentWantsWrite)
FD_SET(fd, &writeSet);
#endif

timeout.tv_sec = 1;
timeout.tv_usec = 0;
bytes = select(fd + 1, &readSet, NULL, &errSet, &timeout);
bytes = select(fd + 1, &readSet, &writeSet, &errSet, &timeout);
if (bytes < 0) {
#ifdef USE_WINDOWS_API
if (WSAGetLastError() == WSAEINTR)
Expand All @@ -659,6 +676,19 @@ static THREAD_RET readPeer(void* in)
FD_SET(fd, &readSet);
}
wc_LockMutex(&args->lock);
#ifdef WOLFSSH_AGENT
/* Retry the owed reply on any wake */
if (agentOwed && !stop) {
int relayRet = wolfSSH_AGENT_RelayChannel(args->ssh, agentChannel);

agentOwed = AgentRelayHeld(relayRet, &agentWantsWrite);
if (relayRet < 0 && !agentOwed) {
args->readError = relayRet;
stop = 1;
bytes = 0;
}
}
#endif
while (bytes > 0 && (FD_ISSET(fd, &readSet) || FD_ISSET(fd, &errSet))) {
/* there is something to read off the wire */
WMEMSET(buf, 0, bufSz);
Expand Down Expand Up @@ -687,36 +717,31 @@ static THREAD_RET readPeer(void* in)
}
#ifdef WOLFSSH_AGENT
else if (err == WS_CHAN_RXD) {
byte agentBuf[512];
int rxd, txd;
word32 channel = 0;

wolfSSH_GetLastRxId(args->ssh, &channel);
rxd = wolfSSH_ChannelIdRead(args->ssh, channel,
agentBuf, sizeof(agentBuf));
if (rxd > 4) {
word32 msgSz = 0;

ato32(agentBuf, &msgSz);
if (msgSz > (word32)rxd - 4) {
rxd += wolfSSH_ChannelIdRead(args->ssh, channel,
agentBuf + rxd,
sizeof(agentBuf) - rxd);
}

txd = rxd;
rxd = sizeof(agentBuf);
ret = wolfSSH_AGENT_Relay(args->ssh,
agentBuf, (word32*)&txd,
agentBuf, (word32*)&rxd);
if (ret == WS_SUCCESS) {
ret = wolfSSH_ChannelIdSend(args->ssh, channel,
agentBuf, rxd);
}
}
WMEMSET(agentBuf, 0, sizeof(agentBuf));
continue;
if (wolfSSH_GetLastRxId(args->ssh, &channel)
== WS_SUCCESS) {
ret = wolfSSH_AGENT_RelayChannel(args->ssh, channel);
agentChannel = channel;
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agentOwed = AgentRelayHeld(ret, &agentWantsWrite);
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}
else {
ret = WS_FATAL_ERROR;
agentOwed = 0;
}
if (ret < 0 && !agentOwed) {
/* Stop the read thread; the channel is no longer
* safe to send on. */
args->readError = ret;
stop = 1;
bytes = 0;
}
/* Back to select(), which is where the owed reply is
* retried. */
if (agentOwed)
bytes = 0;
continue;
}
#endif /* WOLFSSH_AGENT */
else if (err == WS_CBIO_ERR_CONN_CLOSE ||
err == WS_SOCKET_ERROR_E ||
Expand Down
91 changes: 62 additions & 29 deletions examples/client/client.c
View file
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Original file line number Diff line number Diff line change
Expand Up @@ -401,11 +401,16 @@ static THREAD_RET readInput(void* in)
return THREAD_RET_SUCCESS;
}

#if defined(WOLFSSH_AGENT)
static inline void ato32(const byte* c, word32* u32)
#ifdef WOLFSSH_AGENT
/* Statuses that say the relay still owes a reply rather than failing. */
static int AgentRelayHeld(int code, int* wantsWrite)
{
*u32 = (c[0] << 24) | (c[1] << 16) | (c[2] << 8) | c[3];
*wantsWrite = (code == WS_WANT_WRITE);
return code == WS_WANT_WRITE || code == WS_WINDOW_FULL
|| code == WS_REKEYING;
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}


#endif

static THREAD_RET readPeer(void* in)
Expand All @@ -420,7 +425,14 @@ static THREAD_RET readPeer(void* in)
HANDLE stdoutHandle = GetStdHandle(STD_OUTPUT_HANDLE);
#endif
fd_set readSet;
fd_set writeSet;
fd_set errSet;
#ifdef WOLFSSH_AGENT
struct timeval timeout;
word32 agentChannel = 0;
int agentOwed = 0;
int agentWantsWrite = 0;
#endif

#ifdef USE_WINDOWS_API
if (args->rawMode == 0) {
Expand Down Expand Up @@ -456,11 +468,26 @@ static THREAD_RET readPeer(void* in)

/* select() clears the sets, re-arm them every pass. */
FD_ZERO(&readSet);
FD_ZERO(&writeSet);
FD_ZERO(&errSet);
FD_SET(fd, &readSet);
FD_SET(fd, &errSet);

bytes = select(fd + 1, &readSet, NULL, &errSet, NULL);
#ifdef WOLFSSH_AGENT
/* Only a reply the transport is holding waits on a writable socket.
* One held by the peer's window or a rekey waits on the timeout. */
if (agentWantsWrite)
FD_SET(fd, &writeSet);

/* Time out so an owed reply is retried on a silent peer. Without one
* the wait stays event driven. */
timeout.tv_sec = 1;
timeout.tv_usec = 0;
bytes = select(fd + 1, &readSet, &writeSet, &errSet,
agentOwed ? &timeout : NULL);
#else
bytes = select(fd + 1, &readSet, &writeSet, &errSet, NULL);
#endif
if (bytes < 0) {
#ifdef USE_WINDOWS_API
if (WSAGetLastError() == WSAEINTR)
Expand All @@ -475,6 +502,18 @@ static THREAD_RET readPeer(void* in)
break;
}
wc_LockMutex(&args->lock);
#ifdef WOLFSSH_AGENT
/* Retry the owed reply on any wake */
if (agentOwed) {
int relayRet = wolfSSH_AGENT_RelayChannel(args->ssh, agentChannel);

agentOwed = AgentRelayHeld(relayRet, &agentWantsWrite);
if (relayRet < 0 && !agentOwed) {
wc_UnLockMutex(&args->lock);
break;
}
}
#endif
while (bytes > 0 && (FD_ISSET(fd, &readSet) || FD_ISSET(fd, &errSet))) {
/* there is something to read off the wire */
WMEMSET(buf, 0, bufSz);
Expand Down Expand Up @@ -504,34 +543,28 @@ static THREAD_RET readPeer(void* in)
}
#ifdef WOLFSSH_AGENT
else if (ret == WS_CHAN_RXD) {
byte agentBuf[512];
int rxd, txd;
word32 channel = 0;

wolfSSH_GetLastRxId(args->ssh, &channel);
rxd = wolfSSH_ChannelIdRead(args->ssh, channel,
agentBuf, sizeof(agentBuf));
if (rxd > 4) {
word32 msgSz = 0;

ato32(agentBuf, &msgSz);
if (msgSz > (word32)rxd - 4) {
rxd += wolfSSH_ChannelIdRead(args->ssh, channel,
agentBuf + rxd,
sizeof(agentBuf) - rxd);
}

txd = rxd;
rxd = sizeof(agentBuf);
ret = wolfSSH_AGENT_Relay(args->ssh,
agentBuf, (word32*)&txd,
agentBuf, (word32*)&rxd);
if (ret == WS_SUCCESS) {
ret = wolfSSH_ChannelIdSend(args->ssh, channel,
agentBuf, rxd);
}
if (wolfSSH_GetLastRxId(args->ssh, &channel)
== WS_SUCCESS) {
ret = wolfSSH_AGENT_RelayChannel(args->ssh,
channel);
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agentChannel = channel;
agentOwed = AgentRelayHeld(ret, &agentWantsWrite);
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}
else {
ret = WS_FATAL_ERROR;
agentOwed = 0;
}
if (ret < 0 && !agentOwed) {
/* Leave the read loop; the channel is no
* longer safe to send on. */
break;
}
WMEMSET(agentBuf, 0, sizeof(agentBuf));
/* Back to select(), which is where the owed reply
* is retried. */
if (agentOwed)
bytes = 0;
continue;
}
#endif /* WOLFSSH_AGENT */
Expand Down
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