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Reduce the number of round-trips involved in opening an SSH-2 session

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by sending most of the initial SSH_MSG_CHANNEL_REQUEST messages before
waiting for any replies.  The initial version of this code was a clever
thing with a two-pass loop, but that got hairy so I went for the simpler
approach of separating the request and reply code and having flags to
keep track of which requests have been sent.

[originally from svn r9599]
This commit is contained in:
Ben Harris 2012-08-02 22:18:18 +00:00
parent 8ae3278d0c
commit 37ea0f4541
1 changed files with 112 additions and 87 deletions
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199
ssh.c
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@ -7512,6 +7512,9 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
int siglen, retlen, len;
char *q, *agentreq, *ret;
int try_send;
int requested_x11;
int requested_agent;
int requested_tty;
int num_env, env_left, env_ok;
struct Packet *pktout;
Filename *keyfile;
@ -8998,6 +9001,17 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
ssh2_pkt_send(ssh, s->pktout);
}
/*
* Enable port forwardings.
*/
ssh_setup_portfwd(ssh, ssh->conf);
/*
* Send the CHANNEL_REQUESTS for the main channel. We send them all
* and then start looking for responses, so it's important that the
* sending and receiving code below it is kept in sync.
*/
/*
* Potentially enable X11 forwarding.
*/
@ -9023,26 +9037,9 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
end_log_omission(ssh, s->pktout);
ssh2_pkt_adduint32(s->pktout, ssh->x11disp->screennum);
ssh2_pkt_send(ssh, s->pktout);
crWaitUntilV(pktin);
if (pktin->type != SSH2_MSG_CHANNEL_SUCCESS) {
if (pktin->type != SSH2_MSG_CHANNEL_FAILURE) {
bombout(("Unexpected response to X11 forwarding request:"
" packet type %d", pktin->type));
crStopV;
}
logevent("X11 forwarding refused");
} else {
logevent("X11 forwarding enabled");
ssh->X11_fwd_enabled = TRUE;
}
}
/*
* Enable port forwardings.
*/
ssh_setup_portfwd(ssh, ssh->conf);
s->requested_x11 = TRUE;
} else
s->requested_x11 = FALSE;
/*
* Potentially enable agent forwarding.
@ -9054,21 +9051,9 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
ssh2_pkt_addstring(s->pktout, "auth-agent-req@openssh.com");
ssh2_pkt_addbool(s->pktout, 1); /* want reply */
ssh2_pkt_send(ssh, s->pktout);
crWaitUntilV(pktin);
if (pktin->type != SSH2_MSG_CHANNEL_SUCCESS) {
if (pktin->type != SSH2_MSG_CHANNEL_FAILURE) {
bombout(("Unexpected response to agent forwarding request:"
" packet type %d", pktin->type));
crStopV;
}
logevent("Agent forwarding refused");
} else {
logevent("Agent forwarding enabled");
ssh->agentfwd_enabled = TRUE;
}
}
s->requested_agent = TRUE;
} else
s->requested_agent = FALSE;
/*
* Now allocate a pty for the session.
@ -9097,7 +9082,75 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
ssh2_pkt_addstring_data(s->pktout, "\0", 1); /* TTY_OP_END */
ssh2_pkt_send(ssh, s->pktout);
ssh->state = SSH_STATE_INTERMED;
s->requested_tty = TRUE;
} else
s->requested_tty = FALSE;
/*
* Send environment variables.
*
* Simplest thing here is to send all the requests at once, and
* then wait for a whole bunch of successes or failures.
*/
s->num_env = 0;
if (ssh->mainchan && !ssh->ncmode) {
char *key, *val;
for (val = conf_get_str_strs(ssh->conf, CONF_environmt, NULL, &key);
val != NULL;
val = conf_get_str_strs(ssh->conf, CONF_environmt, key, &key)) {
s->pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
ssh2_pkt_adduint32(s->pktout, ssh->mainchan->remoteid);
ssh2_pkt_addstring(s->pktout, "env");
ssh2_pkt_addbool(s->pktout, 1); /* want reply */
ssh2_pkt_addstring(s->pktout, key);
ssh2_pkt_addstring(s->pktout, val);
ssh2_pkt_send(ssh, s->pktout);
s->num_env++;
}
if (s->num_env)
logeventf(ssh, "Sent %d environment variables", s->num_env);
}
/*
* All CHANNEL_REQUESTs sent. Now collect up the replies. These
* must be in precisely the same order as the requests.
*/
if (s->requested_x11) {
crWaitUntilV(pktin);
if (pktin->type != SSH2_MSG_CHANNEL_SUCCESS) {
if (pktin->type != SSH2_MSG_CHANNEL_FAILURE) {
bombout(("Unexpected response to X11 forwarding request:"
" packet type %d", pktin->type));
crStopV;
}
logevent("X11 forwarding refused");
} else {
logevent("X11 forwarding enabled");
ssh->X11_fwd_enabled = TRUE;
}
}
if (s->requested_agent) {
crWaitUntilV(pktin);
if (pktin->type != SSH2_MSG_CHANNEL_SUCCESS) {
if (pktin->type != SSH2_MSG_CHANNEL_FAILURE) {
bombout(("Unexpected response to agent forwarding request:"
" packet type %d", pktin->type));
crStopV;
}
logevent("Agent forwarding refused");
} else {
logevent("Agent forwarding enabled");
ssh->agentfwd_enabled = TRUE;
}
}
if (s->requested_tty) {
crWaitUntilV(pktin);
if (pktin->type != SSH2_MSG_CHANNEL_SUCCESS) {
@ -9117,63 +9170,35 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
ssh->editing = ssh->echoing = 1;
}
/*
* Send environment variables.
*
* Simplest thing here is to send all the requests at once, and
* then wait for a whole bunch of successes or failures.
*/
if (ssh->mainchan && !ssh->ncmode) {
char *key, *val;
if (s->num_env) {
s->env_ok = 0;
s->env_left = s->num_env;
s->num_env = 0;
while (s->env_left > 0) {
crWaitUntilV(pktin);
for (val = conf_get_str_strs(ssh->conf, CONF_environmt, NULL, &key);
val != NULL;
val = conf_get_str_strs(ssh->conf, CONF_environmt, key, &key)) {
s->pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
ssh2_pkt_adduint32(s->pktout, ssh->mainchan->remoteid);
ssh2_pkt_addstring(s->pktout, "env");
ssh2_pkt_addbool(s->pktout, 1); /* want reply */
ssh2_pkt_addstring(s->pktout, key);
ssh2_pkt_addstring(s->pktout, val);
ssh2_pkt_send(ssh, s->pktout);
if (pktin->type != SSH2_MSG_CHANNEL_SUCCESS) {
if (pktin->type != SSH2_MSG_CHANNEL_FAILURE) {
bombout(("Unexpected response to environment request:"
" packet type %d", pktin->type));
crStopV;
}
} else {
s->env_ok++;
}
s->num_env++;
s->env_left--;
}
if (s->num_env) {
logeventf(ssh, "Sent %d environment variables", s->num_env);
s->env_ok = 0;
s->env_left = s->num_env;
while (s->env_left > 0) {
crWaitUntilV(pktin);
if (pktin->type != SSH2_MSG_CHANNEL_SUCCESS) {
if (pktin->type != SSH2_MSG_CHANNEL_FAILURE) {
bombout(("Unexpected response to environment request:"
" packet type %d", pktin->type));
crStopV;
}
} else {
s->env_ok++;
}
s->env_left--;
}
if (s->env_ok == s->num_env) {
logevent("All environment variables successfully set");
} else if (s->env_ok == 0) {
logevent("All environment variables refused");
c_write_str(ssh, "Server refused to set environment variables\r\n");
} else {
logeventf(ssh, "%d environment variables refused",
s->num_env - s->env_ok);
c_write_str(ssh, "Server refused to set all environment variables\r\n");
}
if (s->env_ok == s->num_env) {
logevent("All environment variables successfully set");
} else if (s->env_ok == 0) {
logevent("All environment variables refused");
c_write_str(ssh, "Server refused to set environment variables\r\n");
} else {
logeventf(ssh, "%d environment variables refused",
s->num_env - s->env_ok);
c_write_str(ssh, "Server refused to set all environment variables\r\n");
}
}