PSCP now uses the modern SFTP protocol if it can, and falls back to

[u/mdw/putty] / ssh.c

diff --git a/ssh.c b/ssh.c
index f8ba521..2c53823 100644 (file)
--- a/ssh.c
+++ b/ssh.c
@@ -428,6 +428,13 @@ static struct Packet pktout = { 0, 0, NULL, NULL, 0 };
 static unsigned char *deferred_send_data = NULL;
 static int deferred_len = 0, deferred_size = 0;
 
+/*
+ * Gross hack: pscp will try to start SFTP but fall back to scp1 if
+ * that fails. This variable is the means by which scp.c can reach
+ * into the SSH code and find out which one it got.
+ */
+int ssh_fallback_cmd = 0;
+
 static int ssh_version;
 static int ssh1_throttle_count;
 static int ssh_overall_bufsize;
@@ -2663,12 +2670,26 @@ static void ssh1_protocol(unsigned char *in, int inlen, int ispkt)
        zlib_decompress_init();
     }
 
-    if (*cfg.remote_cmd_ptr)
-       send_packet(SSH1_CMSG_EXEC_CMD, PKT_STR, cfg.remote_cmd_ptr,
-                   PKT_END);
-    else
-       send_packet(SSH1_CMSG_EXEC_SHELL, PKT_END);
-    logevent("Started session");
+    /*
+     * Start the shell or command.
+     * 
+     * Special case: if the first-choice command is an SSH2
+     * subsystem (hence not usable here) and the second choice
+     * exists, we fall straight back to that.
+     */
+    {
+       char *cmd = cfg.remote_cmd_ptr;
+       
+       if (cfg.ssh_subsys && cfg.remote_cmd_ptr2) {
+           cmd = cfg.remote_cmd_ptr2;
+           ssh_fallback_cmd = TRUE;
+       }
+       if (*cmd)
+           send_packet(SSH1_CMSG_EXEC_CMD, PKT_STR, cmd, PKT_END);
+       else
+           send_packet(SSH1_CMSG_EXEC_SHELL, PKT_END);
+       logevent("Started session");
+    }
 
     ssh_state = SSH_STATE_SESSION;
     if (size_needed)
@@ -4492,43 +4513,70 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt)
     }
 
     /*
-     * Start a shell or a remote command.
+     * Start a shell or a remote command. We may have to attempt
+     * this twice if the config data has provided a second choice
+     * of command.
      */
-    ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
-    ssh2_pkt_adduint32(mainchan->remoteid);    /* recipient channel */
-    if (cfg.ssh_subsys) {
-       ssh2_pkt_addstring("subsystem");
-       ssh2_pkt_addbool(1);           /* want reply */
-       ssh2_pkt_addstring(cfg.remote_cmd_ptr);
-    } else if (*cfg.remote_cmd_ptr) {
-       ssh2_pkt_addstring("exec");
-       ssh2_pkt_addbool(1);           /* want reply */
-       ssh2_pkt_addstring(cfg.remote_cmd_ptr);
-    } else {
-       ssh2_pkt_addstring("shell");
-       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->v.v2.remwindow += ssh2_pkt_getuint32();
+    while (1) {
+       int subsys;
+       char *cmd;
+
+       if (ssh_fallback_cmd) {
+           subsys = cfg.ssh_subsys2;
+           cmd = cfg.remote_cmd_ptr2;
+       } else {
+           subsys = cfg.ssh_subsys;
+           cmd = cfg.remote_cmd_ptr;
        }
-    } 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 shell/command request"));
+
+       ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
+       ssh2_pkt_adduint32(mainchan->remoteid); /* recipient channel */
+       if (subsys) {
+           ssh2_pkt_addstring("subsystem");
+           ssh2_pkt_addbool(1);               /* want reply */
+           ssh2_pkt_addstring(cmd);
+       } else if (*cmd) {
+           ssh2_pkt_addstring("exec");
+           ssh2_pkt_addbool(1);               /* want reply */
+           ssh2_pkt_addstring(cmd);
+       } else {
+           ssh2_pkt_addstring("shell");
+           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->v.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 shell/command request"));
+               crReturnV;
+           }
+           /*
+            * We failed to start the command. If this is the
+            * fallback command, we really are finished; if it's
+            * not, and if the fallback command exists, try falling
+            * back to it before complaining.
+            */
+           if (!ssh_fallback_cmd && cfg.remote_cmd_ptr2 != NULL) {
+               logevent("Primary command failed; attempting fallback");
+               ssh_fallback_cmd = TRUE;
+               continue;
+           }
+           bombout(("Server refused to start a shell/command"));
            crReturnV;
+       } else {
+           logevent("Started a shell/command");
        }
-       bombout(("Server refused to start a shell/command"));
-       crReturnV;
-    } else {
-       logevent("Started a shell/command");
+       break;
     }
 
     ssh_state = SSH_STATE_SESSION;
@@ -4882,6 +4930,7 @@ static char *ssh_init(char *host, int port, char **realhost)
     ssh_echoing = 0;
     ssh1_throttle_count = 0;
     ssh_overall_bufsize = 0;
+    ssh_fallback_cmd = 0;
 
     p = connect_to_host(host, port, realhost);
     if (p != NULL)