Backport of the proxycommand feature

include/libssh/libssh.h

@@ -264,7 +264,8 @@ enum ssh_options_e {
   SSH_OPTIONS_CIPHERS_C_S,
   SSH_OPTIONS_CIPHERS_S_C,
   SSH_OPTIONS_COMPRESSION_C_S,
-  SSH_OPTIONS_COMPRESSION_S_C
+  SSH_OPTIONS_COMPRESSION_S_C,
+  SSH_OPTIONS_PROXYCOMMAND
 };
 
 enum {

include/libssh/session.h

@@ -114,6 +114,7 @@ struct ssh_session_struct {
     socket_t fd;
     int ssh2;
     int ssh1;
+    char *ProxyCommand;
 };
 
 int ssh_handle_packets(ssh_session session);

include/libssh/socket.h

@@ -52,4 +52,10 @@ int ssh_socket_get_status(struct socket *s);
 int ssh_socket_data_available(struct socket *s);
 int ssh_socket_data_writable(struct socket *s);
 
+#ifndef _WIN32
+void ssh_execute_command(const char *command, socket_t in, socket_t out);
+socket_t ssh_socket_connect_proxycommand(ssh_session session,
+    const char *command);
+#endif
+
 #endif /* SOCKET_H_ */

libssh/client.c

@@ -497,13 +497,18 @@ int ssh_connect(ssh_session session) {
     leave_function();
     return SSH_ERROR;
   }
-  if (session->fd == -1 && session->host == NULL) {
+  if (session->fd == -1 && session->host == NULL &&
+      session->ProxyCommand == NULL) {
     ssh_set_error(session, SSH_FATAL, "Hostname required");
     leave_function();
     return SSH_ERROR;
   }
   if (session->fd != -1) {
     fd = session->fd;
+#ifndef _WIN32
+  } else if (session->ProxyCommand != NULL) {
+    fd=ssh_socket_connect_proxycommand(session, session->ProxyCommand);
+#endif
   } else {
     fd = ssh_connect_host(session, session->host, session->bindaddr,
         session->port, session->timeout, session->timeout_usec);

libssh/config.c

@@ -38,7 +38,8 @@ enum ssh_config_opcode_e {
   SOC_CIPHERS,
   SOC_COMPRESSION,
   SOC_TIMEOUT,
-  SOC_PROTOCOL
+  SOC_PROTOCOL,
+  SOC_PROXYCOMMAND
 };
 
 struct ssh_config_keyword_table_s {
@@ -56,6 +57,7 @@ static struct ssh_config_keyword_table_s ssh_config_keyword_table[] = {
   { "compression", SOC_COMPRESSION },
   { "connecttimeout", SOC_TIMEOUT },
   { "protocol", SOC_PROTOCOL },
+  { "proxycommand", SOC_PROXYCOMMAND },
   { NULL, SOC_UNSUPPORTED }
 };
 
@@ -274,6 +276,12 @@ static int ssh_config_parse_line(ssh_session session, const char *line,
         ssh_options_set(session, SSH_OPTIONS_TIMEOUT, &i);
       }
       break;
+    case SOC_PROXYCOMMAND:
+      p = ssh_config_get_str(&s, NULL);
+      if (p && *parsing) {
+        ssh_options_set(session, SSH_OPTIONS_PROXYCOMMAND, p);
+      }
+      break;
     case SOC_UNSUPPORTED:
       fprintf(stderr, "Unsupported option: %s, line: %d\n", keyword, count);
       break;

libssh/options.c

@@ -362,6 +362,10 @@ char *dir_expand_dup(ssh_session session, const char *value, int allowsshdir) {
  *                        Set the compression to use for server to client
  *                        communication (string, "none" or "zlib").
  *
+ *                      - SSH_OPTIONS_PROXYCOMMAND:
+ *                        Set the command to be executed in order to connect to
+ *                        server.
+ *
  * @param  value        The value to set. This is a generic pointer and the
  *                      datatype which is used should be set according to the
  *                      type set.
@@ -612,6 +616,14 @@ int ssh_options_set(ssh_session session, enum ssh_options_e type,
           return -1;
       }
       break;
+    case SSH_OPTIONS_PROXYCOMMAND:
+      if (value == NULL) {
+        ssh_set_error_invalid(session, __FUNCTION__);
+        return -1;
+      } else {
+        session->ProxyCommand = strdup(value);
+      }
+      break;
     default:
       ssh_set_error(session, SSH_REQUEST_DENIED, "Unknown ssh option %d", type);
       return -1;

libssh/session.c

@@ -213,6 +213,7 @@ void ssh_free(ssh_session session) {
   SAFE_FREE(session->host);
   SAFE_FREE(session->sshdir);
   SAFE_FREE(session->knownhosts);
+  SAFE_FREE(session->ProxyCommand);
 
   for (i = 0; i < 10; i++) {
     if (session->wanted_methods[i]) {

libssh/socket.c

@@ -32,6 +32,7 @@
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <sys/un.h>
+extern const char **environ;
 #endif
 #include "libssh/priv.h"
 #include "libssh/socket.h"
@@ -39,6 +40,7 @@
 #include "libssh/poll.h"
 #include "libssh/session.h"
 
+
 /** \defgroup ssh_socket SSH Sockets
  * \addtogroup ssh_socket
  * @{
@@ -658,6 +660,54 @@ int ssh_socket_get_status(struct socket *s) {
   return r;
 }
 
+#ifndef _WIN32
+/**
+ * @internal
+ * @brief executes a command and redirect input and outputs
+ * @param command command to execute
+ * @param in input file descriptor
+ * @param out output file descriptor
+ */
+void ssh_execute_command(const char *command, socket_t in, socket_t out){
+  const char *args[]={"/bin/sh","-c",command,NULL};
+  /* redirect in and out to stdin, stdout and stderr */
+  dup2(in, 0);
+  dup2(out,1);
+  dup2(out,2);
+  close(in);
+  close(out);
+  execve(args[0],(char * const *)args,(char * const *)environ);
+  exit(1);
+}
+
+/**
+ * @internal
+ * @brief Open a socket on a ProxyCommand
+ * This call will always be nonblocking.
+ * @param s    socket to connect.
+ * @param command Command to execute.
+ * @returns SSH_OK socket is being connected.
+ * @returns SSH_ERROR error while executing the command.
+ */
+
+socket_t ssh_socket_connect_proxycommand(ssh_session session,
+    const char *command){
+  socket_t fd[2];
+  int pid;
+  enter_function();
+  socketpair(AF_UNIX,SOCK_STREAM,0,fd);
+  pid = fork();
+  if(pid == 0){
+    ssh_execute_command(command,fd[1],fd[1]);
+  }
+  close(fd[1]);
+  ssh_log(session,SSH_LOG_PROTOCOL,"ProxyCommand connection pipe: [%d,%d]",fd[0],fd[1]);
+  return fd[0];
+}
+
+#endif /* _WIN32 */
+
+
 /** @}
  */
 /* vim: set ts=2 sw=2 et cindent: */