- djm@cvs.openbsd.org 2007/09/04 11:15:56

     [ssh.c sshconnect.c sshconnect.h]
     make ssh(1)'s ConnectTimeout option apply to both the TCP connection and
     SSH banner exchange (previously it just covered the TCP connection).
     This allows callers of ssh(1) to better detect and deal with stuck servers
     that accept a TCP connection but don't progress the protocol, and also
     makes ConnectTimeout useful for connections via a ProxyCommand;
     feedback and "looks ok" markus@

1 files changed, 84 insertions, 21 deletions

diff --git a/sshconnect.c b/sshconnect.c
index 7e3c9fff4..933df39fa 100644
--- a/sshconnect.c
+++ b/sshconnect.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: sshconnect.c,v 1.201 2007/08/23 03:23:26 djm Exp $ */
+/* $OpenBSD: sshconnect.c,v 1.202 2007/09/04 11:15:55 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -77,6 +77,23 @@ extern pid_t proxy_command_pid;
 static int show_other_keys(const char *, Key *);
 static void warn_changed_key(Key *);
 
+static void
+ms_subtract_diff(struct timeval *start, int *ms)
+{
+        struct timeval diff, finish;
+
+        gettimeofday(&finish, NULL);
+        timersub(&finish, start, &diff);        
+        *ms -= (diff.tv_sec * 1000) + (diff.tv_usec / 1000);
+}
+
+static void
+ms_to_timeval(struct timeval *tv, int ms)
+{
+        tv->tv_sec = ms / 1000;
+        tv->tv_usec = (ms % 1000) * 1000;
+}
+
 /*
  * Connect to the given ssh server using a proxy command.
  */
@@ -223,30 +240,36 @@ ssh_create_socket(int privileged, struct addrinfo *ai)
 
 static int
 timeout_connect(int sockfd, const struct sockaddr *serv_addr,
-    socklen_t addrlen, int timeout)
+    socklen_t addrlen, int *timeoutp)
 {
         fd_set *fdset;
-        struct timeval tv;
+        struct timeval tv, t_start;
         socklen_t optlen;
         int optval, rc, result = -1;
 
-        if (timeout <= 0)
-                return (connect(sockfd, serv_addr, addrlen));
+        gettimeofday(&t_start, NULL);
+
+        if (*timeoutp <= 0) {
+                result = connect(sockfd, serv_addr, addrlen);
+                goto done;
+        }
 
         set_nonblock(sockfd);
         rc = connect(sockfd, serv_addr, addrlen);
         if (rc == 0) {
                 unset_nonblock(sockfd);
-                return (0);
+                result = 0;
+                goto done;
+        }
+        if (errno != EINPROGRESS) {
+                result = -1;
+                goto done;
         }
-        if (errno != EINPROGRESS)
-                return (-1);
 
         fdset = (fd_set *)xcalloc(howmany(sockfd + 1, NFDBITS),
             sizeof(fd_mask));
         FD_SET(sockfd, fdset);
-        tv.tv_sec = timeout;
-        tv.tv_usec = 0;
+        ms_to_timeval(&tv, *timeoutp);
 
         for (;;) {
                 rc = select(sockfd + 1, NULL, fdset, NULL, &tv);
@@ -285,6 +308,16 @@ timeout_connect(int sockfd, const struct sockaddr *serv_addr,
         }
 
         xfree(fdset);
+
+ done:
+        if (result == 0 && *timeoutp > 0) {
+                ms_subtract_diff(&t_start, timeoutp);
+                if (*timeoutp <= 0) {
+                        errno = ETIMEDOUT;
+                        result = -1;
+                }
+        }
+
         return (result);
 }
 
@@ -301,8 +334,8 @@ timeout_connect(int sockfd, const struct sockaddr *serv_addr,
  */
 int
 ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
-    u_short port, int family, int connection_attempts,
-    int needpriv, const char *proxy_command)
+    u_short port, int family, int connection_attempts, int *timeout_ms,
+    int want_keepalive, int needpriv, const char *proxy_command)
 {
         int gaierr;
         int on = 1;
@@ -355,7 +388,7 @@ ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
                                 continue;
 
                         if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
-                            options.connection_timeout) >= 0) {
+                            timeout_ms) >= 0) {
                                 /* Successful connection. */
                                 memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
                                 break;
@@ -382,7 +415,7 @@ ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
         debug("Connection established.");
 
         /* Set SO_KEEPALIVE if requested. */
-        if (options.tcp_keep_alive &&
+        if (want_keepalive &&
             setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
             sizeof(on)) < 0)
                 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
@@ -398,7 +431,7 @@ ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
  * identification string.
  */
 static void
-ssh_exchange_identification(void)
+ssh_exchange_identification(int timeout_ms)
 {
         char buf[256], remote_version[256];     /* must be same size! */
         int remote_major, remote_minor, mismatch;
@@ -406,16 +439,44 @@ ssh_exchange_identification(void)
         int connection_out = packet_get_connection_out();
         int minor1 = PROTOCOL_MINOR_1;
         u_int i, n;
+        size_t len;
+        int fdsetsz, remaining, rc;
+        struct timeval t_start, t_remaining;
+        fd_set *fdset;
+
+        fdsetsz = howmany(connection_in + 1, NFDBITS) * sizeof(fd_mask);
+        fdset = xcalloc(1, fdsetsz);
 
         /* Read other side's version identification. */
+        remaining = timeout_ms;
         for (n = 0;;) {
                 for (i = 0; i < sizeof(buf) - 1; i++) {
-                        size_t len = atomicio(read, connection_in, &buf[i], 1);
+                        if (timeout_ms > 0) {
+                                gettimeofday(&t_start, NULL);
+                                ms_to_timeval(&t_remaining, remaining);
+                                FD_SET(connection_in, fdset);
+                                rc = select(connection_in + 1, fdset, NULL,
+                                    fdset, &t_remaining);
+                                ms_subtract_diff(&t_start, &remaining);
+                                if (rc == 0 || remaining <= 0)
+                                        fatal("Connection timed out during "
+                                            "banner exchange");
+                                if (rc == -1) {
+                                        if (errno == EINTR)
+                                                continue;
+                                        fatal("ssh_exchange_identification: "
+                                            "select: %s", strerror(errno));
+                                }
+                        }
+
+                        len = atomicio(read, connection_in, &buf[i], 1);
 
                         if (len != 1 && errno == EPIPE)
-                                fatal("ssh_exchange_identification: Connection closed by remote host");
+                                fatal("ssh_exchange_identification: "
+                                    "Connection closed by remote host");
                         else if (len != 1)
-                                fatal("ssh_exchange_identification: read: %.100s", strerror(errno));
+                                fatal("ssh_exchange_identification: "
+                                    "read: %.100s", strerror(errno));
                         if (buf[i] == '\r') {
                                 buf[i] = '\n';
                                 buf[i + 1] = 0;
@@ -426,7 +487,8 @@ ssh_exchange_identification(void)
                                 break;
                         }
                         if (++n > 65536)
-                                fatal("ssh_exchange_identification: No banner received");
+                                fatal("ssh_exchange_identification: "
+                                    "No banner received");
                 }
                 buf[sizeof(buf) - 1] = 0;
                 if (strncmp(buf, "SSH-", 4) == 0)
@@ -434,6 +496,7 @@ ssh_exchange_identification(void)
                 debug("ssh_exchange_identification: %s", buf);
         }
         server_version_string = xstrdup(buf);
+        xfree(fdset);
 
         /*
          * Check that the versions match.  In future this might accept
@@ -946,7 +1009,7 @@ verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
  */
 void
 ssh_login(Sensitive *sensitive, const char *orighost,
-    struct sockaddr *hostaddr, struct passwd *pw)
+    struct sockaddr *hostaddr, struct passwd *pw, int timeout_ms)
 {
         char *host, *cp;
         char *server_user, *local_user;
@@ -961,7 +1024,7 @@ ssh_login(Sensitive *sensitive, const char *orighost,
                         *cp = (char)tolower(*cp);
 
         /* Exchange protocol version identification strings with the server. */
-        ssh_exchange_identification();
+        ssh_exchange_identification(timeout_ms);
 
         /* Put the connection into non-blocking mode. */
         packet_set_nonblocking();