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Implement OpenSSH's private agent forwarding extension. I believe we

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now interoperate with OpenSSH/SSH2 to _exactly_ the same level as we
interoperate with SSH1. Which is pretty cool really.

[originally from svn r980]
This commit is contained in:
Simon Tatham 2001-03-03 16:38:44 +00:00
parent 1742f1cd34
commit 16f4ffe616
1 changed files with 89 additions and 1 deletions
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90
ssh.c
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@ -3247,6 +3247,43 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt)
}
}
/*
* Potentially enable agent forwarding.
*/
if (cfg.agentfwd && agent_exists()) {
char proto[20], data[64];
logevent("Requesting OpenSSH-style agent forwarding");
x11_invent_auth(proto, sizeof(proto), data, sizeof(data));
ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
ssh2_pkt_adduint32(mainchan->remoteid);
ssh2_pkt_addstring("auth-agent-req@openssh.com");
ssh2_pkt_addbool(1); /* want reply */
ssh2_pkt_send();
do {
crWaitUntilV(ispkt);
if (pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST) {
unsigned i = ssh2_pkt_getuint32();
struct ssh_channel *c;
c = find234(ssh_channels, &i, ssh_channelfind);
if (!c)
continue; /* nonexistent channel */
c->v2.remwindow += ssh2_pkt_getuint32();
}
} while (pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST);
if (pktin.type != SSH2_MSG_CHANNEL_SUCCESS) {
if (pktin.type != SSH2_MSG_CHANNEL_FAILURE) {
bombout(("Server got confused by agent forwarding request"));
crReturnV;
}
logevent("Agent forwarding refused");
} else {
logevent("Agent forwarding enabled");
ssh_agentfwd_enabled = TRUE;
}
}
/*
* Now allocate a pty for the session.
*/
@ -3369,6 +3406,45 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt)
case CHAN_X11:
x11_send(c->u.x11.s, data, length);
break;
case CHAN_AGENT:
while (length > 0) {
if (c->u.a.lensofar < 4) {
int l = min(4 - c->u.a.lensofar, length);
memcpy(c->u.a.msglen + c->u.a.lensofar, data, l);
data += l; length -= l; c->u.a.lensofar += l;
}
if (c->u.a.lensofar == 4) {
c->u.a.totallen = 4 + GET_32BIT(c->u.a.msglen);
c->u.a.message = smalloc(c->u.a.totallen);
memcpy(c->u.a.message, c->u.a.msglen, 4);
}
if (c->u.a.lensofar >= 4 && length > 0) {
int l = min(c->u.a.totallen - c->u.a.lensofar,
length);
memcpy(c->u.a.message + c->u.a.lensofar, data, l);
data += l; length -= l; c->u.a.lensofar += l;
}
if (c->u.a.lensofar == c->u.a.totallen) {
void *reply, *sentreply;
int replylen;
agent_query(c->u.a.message, c->u.a.totallen,
&reply, &replylen);
if (reply)
sentreply = reply;
else {
/* Fake SSH_AGENT_FAILURE. */
sentreply = "\0\0\0\1\5";
replylen = 5;
}
ssh2_add_channel_data(c, sentreply, replylen);
try_send = TRUE;
if (reply)
sfree(reply);
sfree(c->u.a.message);
c->u.a.lensofar = 0;
}
}
break;
}
/*
* Enlarge the window again at the remote
@ -3401,7 +3477,9 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt)
*/
x11_close(c->u.x11.s);
sshfwd_close(c);
}
} else if (c->type == CHAN_AGENT) {
sshfwd_close(c);
}
} else if (pktin.type == SSH2_MSG_CHANNEL_CLOSE) {
unsigned i = ssh2_pkt_getuint32();
struct ssh_channel *c;
@ -3421,6 +3499,8 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt)
break; /* nothing to see here, move along */
case CHAN_X11:
break;
case CHAN_AGENT:
break;
}
del234(ssh_channels, c);
sfree(c->v2.outbuffer);
@ -3465,6 +3545,14 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt)
} else {
c->type = CHAN_X11;
}
} else if (typelen == 22 &&
!memcmp(type, "auth-agent@openssh.com", 3)) {
if (!ssh_agentfwd_enabled)
error = "Agent forwarding is not enabled";
else {
c->type = CHAN_AGENT; /* identify channel type */
c->u.a.lensofar = 0;
}
} else {
error = "Unsupported channel type requested";
}