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/*
20140120
Jan Mojzis
Public domain.
*/
#include "buf.h"
#include "ssh.h"
#include "e.h"
#include "bug.h"
#include "str.h"
#include "log.h"
#include "packetparser.h"
#include "packet.h"
int packet_channel_request(struct buf *b1, struct buf *b2,
const char *customcmd) {
long long pos = 0;
crypto_uint8 ch, wantreply;
crypto_uint32 id, a, b, x, y;
char *cmd;
crypto_uint32 cmdlen;
char *p1, *p2;
const char *ps;
crypto_uint32 plen1, plen2;
pos = packetparser_uint8(b1->buf, b1->len, pos,
&ch); /* byte SSH_MSG_CHANNEL_REQUEST */
if (ch != SSH_MSG_CHANNEL_REQUEST) bug_proto();
pos = packetparser_uint32(b1->buf, b1->len, pos,
&id); /* uint32 recipient channel */
if (id != channel_getid()) bug_proto();
pos = packetparser_uint32(
b1->buf, b1->len, pos,
&cmdlen); /* string request type in US-ASCII characters only */
cmd = (char *) b1->buf + pos;
pos = packetparser_skip(b1->buf, b1->len, pos, cmdlen);
pos = packetparser_uint8(b1->buf, b1->len, pos,
&wantreply); /* boolean want reply */
cmd[cmdlen] = 0;
if (str_equaln(cmd, cmdlen, "exec")) {
/* byte SSH_MSG_CHANNEL_REQUEST
uint32 recipient channel
string "exec"
boolean want reply
string command
*/
pos = packetparser_uint32(b1->buf, b1->len, pos, &plen1);
p1 = (char *) b1->buf + pos;
pos = packetparser_skip(b1->buf, b1->len, pos, plen1);
pos = packetparser_end(b1->buf, b1->len, pos);
buf_putnum8(b1, 0);
p1[plen1] = 0;
if (customcmd) {
log_d4("packet=SSH_MSG_CHANNEL_REQUEST, exec ", p1,
", rejected: custom program is selected using param. -e ",
customcmd);
goto reject;
}
if (!channel_exec(p1)) bug();
log_d3("packet=SSH_MSG_CHANNEL_REQUEST, exec ", p1, ", accepted");
goto accept;
}
if (str_equaln(cmd, cmdlen, "subsystem")) {
/* byte SSH_MSG_CHANNEL_REQUEST
uint32 recipient channel
string "subsystem"
boolean want reply
string subsystem name
*/
pos = packetparser_uint32(b1->buf, b1->len, pos, &plen1);
p1 = (char *) b1->buf + pos;
pos = packetparser_skip(b1->buf, b1->len, pos, plen1);
pos = packetparser_end(b1->buf, b1->len, pos);
buf_putnum8(b1, 0);
p1[plen1] = 0;
if (customcmd) {
log_d4("packet=SSH_MSG_CHANNEL_REQUEST, subsystem ", p1,
", rejected: custom program is selected using param. -e ",
customcmd);
goto reject;
}
ps = channel_subsystem_get(p1);
if (!ps) {
log_d3("packet=SSH_MSG_CHANNEL_REQUEST, subsystem ", p1,
", rejected");
goto reject;
}
if (!channel_exec(ps)) bug();
log_d5("packet=SSH_MSG_CHANNEL_REQUEST, subsystem ", p1, "=", ps,
", accepted");
goto accept;
}
if (str_equaln(cmd, cmdlen, "shell")) {
/* byte SSH_MSG_CHANNEL_REQUEST
uint32 recipient channel
string "shell"
boolean want reply
*/
pos = packetparser_end(b1->buf, b1->len, pos);
if (customcmd) {
if (!channel_exec(customcmd)) bug();
log_d3("packet=SSH_MSG_CHANNEL_REQUEST, shell, accepted, executing "
"custom shell '",
customcmd, "'");
}
else {
if (!channel_exec(0)) bug();
log_d1("packet=SSH_MSG_CHANNEL_REQUEST, shell, accepted");
}
goto accept;
}
if (str_equaln(cmd, cmdlen, "env")) {
/* byte SSH_MSG_CHANNEL_REQUEST
uint32 recipient channel
string "env"
boolean want reply
string variable name
string variable value
*/
/**/
pos = packetparser_uint32(b1->buf, b1->len, pos,
&plen1); /* string variable name */
p1 = (char *) b1->buf + pos;
pos = packetparser_skip(b1->buf, b1->len, pos, plen1);
pos = packetparser_uint32(b1->buf, b1->len, pos,
&plen2); /* string variable value */
p2 = (char *) b1->buf + pos;
pos = packetparser_skip(b1->buf, b1->len, pos, plen2);
pos = packetparser_end(b1->buf, b1->len, pos);
buf_putnum8(b1, 0);
p1[plen1] = 0;
p2[plen2] = 0;
if (channel_env(p1, p2)) {
log_d5("packet=SSH_MSG_CHANNEL_REQUEST, env ", p1, "=", p2,
", accepted");
goto accept;
}
else {
log_d5("packet=SSH_MSG_CHANNEL_REQUEST, env ", p1, "=", p2,
", rejected");
goto reject;
}
}
if (str_equaln(cmd, cmdlen, "pty-req")) {
/*
byte SSH_MSG_CHANNEL_REQUEST
uint32 recipient channel
string "pty-req"
boolean want_reply
string TERM environment variable value (e.g., vt100)
uint32 terminal width, characters (e.g., 80)
uint32 terminal height, rows (e.g., 24)
uint32 terminal width, pixels (e.g., 640)
uint32 terminal height, pixels (e.g., 480)
string encoded terminal modes
*/
pos = packetparser_uint32(b1->buf, b1->len, pos, &plen1);
p1 = (char *) b1->buf + pos;
pos = packetparser_skip(b1->buf, b1->len, pos, plen1);
pos = packetparser_uint32(b1->buf, b1->len, pos, &a);
pos = packetparser_uint32(b1->buf, b1->len, pos, &b);
pos = packetparser_uint32(b1->buf, b1->len, pos, &x);
pos = packetparser_uint32(b1->buf, b1->len, pos, &y);
pos = packetparser_uint32(b1->buf, b1->len, pos, &plen2);
p2 = (char *) b1->buf + pos;
pos = packetparser_skip(b1->buf, b1->len, pos, plen2);
pos = packetparser_end(b1->buf, b1->len, pos);
buf_putnum8(b1, 0);
/* XXX TODO encoded terminal modes (p2, plen2) */
p1[plen1] = 0;
p2[plen2] = 0;
if (!channel_openterminal(p1, a, b, x, y)) {
log_w1("unable to open terminal");
log_d3("packet=SSH_MSG_CHANNEL_REQUEST, pty-req ", p1,
", rejected");
goto reject;
}
log_d3("packet=SSH_MSG_CHANNEL_REQUEST, pty-req ", p1, ", accepted");
goto accept;
}
if (str_equaln(cmd, cmdlen, "window-change")) {
/*
byte SSH_MSG_CHANNEL_REQUEST
uint32 recipient channel
string "window-change"
boolean FALSE
uint32 terminal width, columns
uint32 terminal height, rows
uint32 terminal width, pixels
uint32 terminal height, pixels
*/
pos = packetparser_uint32(b1->buf, b1->len, pos, &a);
pos = packetparser_uint32(b1->buf, b1->len, pos, &b);
pos = packetparser_uint32(b1->buf, b1->len, pos, &x);
pos = packetparser_uint32(b1->buf, b1->len, pos, &y);
pos = packetparser_end(b1->buf, b1->len, pos);
channel_ptyresize(a, b, x, y);
log_d1("packet=SSH_MSG_CHANNEL_REQUEST, window-change, accepted");
goto accept;
}
log_d3("packet=SSH_MSG_CHANNEL_REQUEST, ", cmd, ", rejected or ignored");
reject:
/* reject channel request */
if (!wantreply) goto done;
buf_purge(b2);
buf_putnum8(b2, SSH_MSG_CHANNEL_FAILURE); /* byte SSH_MSG_CHANNEL_SUCCESS */
buf_putnum32(b2, id); /* uint32 recipient channel */
packet_put(b2);
buf_purge(b1);
buf_purge(b2);
return 1;
accept:
if (!wantreply) goto done;
buf_purge(b2);
buf_putnum8(b2, SSH_MSG_CHANNEL_SUCCESS); /* byte SSH_MSG_CHANNEL_SUCCESS */
buf_putnum32(b2, id); /* uint32 recipient channel */
packet_put(b2);
buf_purge(b1);
buf_purge(b2);
return 1;
done:
buf_purge(b1);
buf_purge(b2);
return 1;
}
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