/*
* Opens a TCP/IP connection to the remote server on the given host.
* The address of the remote host will be returned in hostaddr.
* If port is 0, the default port will be used. If needpriv is true,
* a privileged port will be allocated to make the connection.
* This requires super-user privileges if needpriv is true.
* Connection_attempts specifies the maximum number of tries (one per
* second). If proxy_command is non-NULL, it specifies the command (with %h
* and %p substituted for host and port, respectively) to use to contact
* the daemon.
*/
struct ssh *
ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
u_short port, int family, int connection_attempts, int *timeout_ms,
int want_keepalive, int needpriv, const char *proxy_command)
{
struct ssh *ssh;
int gaierr;
int on = 1;
int sock = -1, attempt;
char ntop[NI_MAXHOST], strport[NI_MAXSERV];
struct addrinfo hints, *ai, *aitop;
debug2("ssh_connect: needpriv %d", needpriv);
/* If a proxy command is given, connect using it. */
if (proxy_command != NULL)
return ssh_proxy_connect(host, port, proxy_command);
/* No proxy command. */
memset(&hints, 0, sizeof(hints));
hints.ai_family = family;
hints.ai_socktype = SOCK_STREAM;
snprintf(strport, sizeof strport, "%u", port);
if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0)
fatal("%s: Could not resolve hostname %.100s: %s", __progname,
host, ssh_gai_strerror(gaierr));
for (attempt = 0; attempt < connection_attempts; attempt++) {
if (attempt > 0) {
/* Sleep a moment before retrying. */
sleep(1);
debug("Trying again...");
}
/*
* Loop through addresses for this host, and try each one in
* sequence until the connection succeeds.
*/
for (ai = aitop; ai; ai = ai->ai_next) {
if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
continue;
if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
ntop, sizeof(ntop), strport, sizeof(strport),
NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
error("ssh_connect: getnameinfo failed");
continue;
}
debug("Connecting to %.200s [%.100s] port %s.",
host, ntop, strport);
/* Create a socket for connecting. */
sock = ssh_create_socket(needpriv, ai);
if (sock < 0)
/* Any error is already output */
continue;
if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
timeout_ms) >= 0) {
/* Successful connection. */
memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
break;
} else {
debug("connect to address %s port %s: %s",
ntop, strport, strerror(errno));
close(sock);
sock = -1;
}
}
if (sock != -1)
break; /* Successful connection. */
}
freeaddrinfo(aitop);
/* Return failure if we didn't get a successful connection. */
if (sock == -1) {
error("ssh: connect to host %s port %s: %s",
host, strport, strerror(errno));
return (NULL);
}
debug("Connection established.");
/* Set SO_KEEPALIVE if requested. */
if (want_keepalive &&
setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
sizeof(on)) < 0)
error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
/* Set the connection. */
ssh = ssh_packet_set_connection(NULL, sock, sock);
ssh_packet_set_timeout(ssh, options.server_alive_interval,
options.server_alive_count_max);
return (ssh);
}
/*
* Connect to the given ssh server using a proxy command.
*/
static struct ssh *
ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
{
struct ssh *ssh;
char *command_string, *tmp;
int pin[2], pout[2];
pid_t pid;
char *shell, strport[NI_MAXSERV];
if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
shell = _PATH_BSHELL;
/* Convert the port number into a string. */
snprintf(strport, sizeof strport, "%hu", port);
/*
* Build the final command string in the buffer by making the
* appropriate substitutions to the given proxy command.
*
* Use "exec" to avoid "sh -c" processes on some platforms
* (e.g. Solaris)
*/
xasprintf(&tmp, "exec %s", proxy_command);
command_string = percent_expand(tmp, "h", host, "p", strport,
"r", options.user, (char *)NULL);
xfree(tmp);
/* Create pipes for communicating with the proxy. */
if (pipe(pin) < 0 || pipe(pout) < 0)
fatal("Could not create pipes to communicate with the proxy: %.100s",
strerror(errno));
debug("Executing proxy command: %.500s", command_string);
/* Fork and execute the proxy command. */
if ((pid = fork()) == 0) {
char *argv[10];
/* Child. Permanently give up superuser privileges. */
permanently_drop_suid(original_real_uid);
/* Redirect stdin and stdout. */
close(pin[1]);
if (pin[0] != 0) {
if (dup2(pin[0], 0) < 0)
perror("dup2 stdin");
close(pin[0]);
}
close(pout[0]);
if (dup2(pout[1], 1) < 0)
perror("dup2 stdout");
/* Cannot be 1 because pin allocated two descriptors. */
close(pout[1]);
/* Stderr is left as it is so that error messages get
printed on the user's terminal. */
argv[0] = shell;
argv[1] = "-c";
argv[2] = command_string;
argv[3] = NULL;
/* Execute the proxy command. Note that we gave up any
extra privileges above. */
signal(SIGPIPE, SIG_DFL);
execv(argv[0], argv);
perror(argv[0]);
exit(1);
}
/* Parent. */
if (pid < 0)
fatal("fork failed: %.100s", strerror(errno));
else
proxy_command_pid = pid; /* save pid to clean up later */
/* Close child side of the descriptors. */
close(pin[0]);
close(pout[1]);
/* Free the command name. */
xfree(command_string);
/* Set the connection file descriptors. */
ssh = ssh_packet_set_connection(NULL, pout[0], pin[1]);
ssh_packet_set_timeout(ssh, options.server_alive_interval,
options.server_alive_count_max);
/* Indicate OK return */
return (ssh);
}
static void
congreet(int s)
{
int n = 0, remote_major = 0, remote_minor = 0;
char buf[256], *cp;
char remote_version[sizeof buf];
size_t bufsiz;
con *c = &fdcon[s];
for (;;) {
memset(buf, '\0', sizeof(buf));
bufsiz = sizeof(buf);
cp = buf;
while (bufsiz-- &&
(n = atomicio(read, s, cp, 1)) == 1 && *cp != '\n') {
if (*cp == '\r')
*cp = '\n';
cp++;
}
if (n != 1 || strncmp(buf, "SSH-", 4) == 0)
break;
}
if (n == 0) {
switch (errno) {
case EPIPE:
error("%s: Connection closed by remote host", c->c_name);
break;
case ECONNREFUSED:
break;
default:
error("read (%s): %s", c->c_name, strerror(errno));
break;
}
conrecycle(s);
return;
}
if (*cp != '\n' && *cp != '\r') {
error("%s: bad greeting", c->c_name);
confree(s);
return;
}
*cp = '\0';
if ((c->c_ssh = ssh_packet_set_connection(NULL, s, s)) == NULL)
fatal("ssh_packet_set_connection failed");
ssh_packet_set_timeout(c->c_ssh, timeout, 1);
ssh_set_app_data(c->c_ssh, c); /* back link */
if (sscanf(buf, "SSH-%d.%d-%[^\n]\n",
&remote_major, &remote_minor, remote_version) == 3)
c->c_ssh->compat = compat_datafellows(remote_version);
else
c->c_ssh->compat = 0;
if (c->c_keytype != KT_RSA1) {
if (!ssh2_capable(remote_major, remote_minor)) {
debug("%s doesn't support ssh2", c->c_name);
confree(s);
return;
}
} else if (remote_major != 1) {
debug("%s doesn't support ssh1", c->c_name);
confree(s);
return;
}
fprintf(stderr, "# %s:%d %s\n", c->c_name, ssh_port, chop(buf));
n = snprintf(buf, sizeof buf, "SSH-%d.%d-OpenSSH-keyscan\r\n",
c->c_keytype == KT_RSA1? PROTOCOL_MAJOR_1 : PROTOCOL_MAJOR_2,
c->c_keytype == KT_RSA1? PROTOCOL_MINOR_1 : PROTOCOL_MINOR_2);
if (n < 0 || (size_t)n >= sizeof(buf)) {
error("snprintf: buffer too small");
confree(s);
return;
}
if (atomicio(vwrite, s, buf, n) != (size_t)n) {
error("write (%s): %s", c->c_name, strerror(errno));
confree(s);
return;
}
if (c->c_keytype != KT_RSA1) {
keygrab_ssh2(c);
confree(s);
return;
}
c->c_status = CS_SIZE;
contouch(s);
}