session: Introduce SSH_TIMEOUT_DEFAULT

The default timeout of 30seconds is very nice when connecting to a new SSH
session, however it completely breaks the synchronous blocking API.
Use SSH_TIMEOUT_DEFAULT when in blocking mode so channel reads&write are blocking
as expected

Reviewed-by: Andreas Schneider <asn@cryptomilk.org>

include/libssh/session.h

@@ -69,8 +69,13 @@ enum ssh_pending_call_e {
 #define SSH_SESSION_FLAG_AUTHENTICATED 2
 
 /* codes to use with ssh_handle_packets*() */
+/* Infinite timeout */
 #define SSH_TIMEOUT_INFINITE -1
+/* Use the timeout defined by user if any. Mostly used with new connections */
 #define SSH_TIMEOUT_USER -2
+/* Use the default timeout, depending on ssh_is_blocking() */
+#define SSH_TIMEOUT_DEFAULT -3
+/* Don't block at all */
 #define SSH_TIMEOUT_NONBLOCKING 0
 
 /* members that are common to ssh_session and ssh_bind */

src/channels.c

@@ -1222,7 +1222,7 @@ static int ssh_waitsession_unblocked(void *s){
  *          SSH_AGAIN Timeout elapsed (or in nonblocking mode)
  */
 int ssh_channel_flush(ssh_channel channel){
-  return ssh_blocking_flush(channel->session, SSH_TIMEOUT_USER);
+  return ssh_blocking_flush(channel->session, SSH_TIMEOUT_DEFAULT);
 }
 
 int channel_write_common(ssh_channel channel, const void *data,
@@ -1282,7 +1282,7 @@ int channel_write_common(ssh_channel channel, const void *data,
   }
 #endif
   if (ssh_waitsession_unblocked(session) == 0){
-    rc = ssh_handle_packets_termination(session, SSH_TIMEOUT_USER,
+    rc = ssh_handle_packets_termination(session, SSH_TIMEOUT_DEFAULT,
             ssh_waitsession_unblocked, session);
     if (rc == SSH_ERROR || !ssh_waitsession_unblocked(session))
         goto out;
@@ -1298,7 +1298,7 @@ int channel_write_common(ssh_channel channel, const void *data,
           /* nothing can be written */
           ssh_log(session, SSH_LOG_PROTOCOL,
                 "Wait for a growing window message...");
-          rc = ssh_handle_packets_termination(session, SSH_TIMEOUT_USER,
+          rc = ssh_handle_packets_termination(session, SSH_TIMEOUT_DEFAULT,
               ssh_channel_waitwindow_termination,channel);
           if (rc == SSH_ERROR || !ssh_channel_waitwindow_termination(channel))
             goto out;
@@ -2681,13 +2681,13 @@ int ssh_channel_read(ssh_channel channel, void *dest, uint32_t count, int is_std
     }
   }
 
-  /* block reading until all bytes are read
+  /* block reading until at least one byte has been read
   *  and ignore the trivial case count=0
   */
   ctx.channel = channel;
   ctx.buffer = stdbuf;
-  ctx.count = count;
+  ctx.count = 1;
-  rc = ssh_handle_packets_termination(session, SSH_TIMEOUT_USER,
+  rc = ssh_handle_packets_termination(session, SSH_TIMEOUT_DEFAULT,
       ssh_channel_read_termination, &ctx);
   if (rc == SSH_ERROR){
     leave_function();

src/session.c

@@ -512,6 +512,7 @@ int ssh_handle_packets(ssh_session session, int timeout) {
  *                      (-1) means an infinite timeout.
  *                      Specifying SSH_TIMEOUT_USER means to use the timeout
  *                      specified in options. 0 means poll will return immediately.
+ *                      SSH_TIMEOUT_DEFAULT uses blocking parameters of the session.
  *                      This parameter is passed to the poll() function.
  *
  * @param[in] fct       Termination function to be used to determine if it is
@@ -530,6 +531,11 @@ int ssh_handle_packets_termination(ssh_session session, int timeout,
                                         session->opts.timeout_usec);
       else
         timeout = SSH_TIMEOUT_NONBLOCKING;
+  } else if (timeout == SSH_TIMEOUT_DEFAULT){
+	  if(ssh_is_blocking(session))
+		  timeout = SSH_TIMEOUT_INFINITE;
+	  else
+		  timeout = SSH_TIMEOUT_NONBLOCKING;
   }
   ssh_timestamp_init(&ts);
   tm = timeout;