SSH: add protocol lock direction

Some protocols have to call the underlying functions without regard to
what exact state the socket signals. For example even if the socket says
"readable", the send function might need to be called while uploading,
or vice versa. This is the case for libssh2 based protocols: SCP and
SFTP and we now introduce a define to set those protocols and we make
the multi interface code aware of this concept.

This is another fix to make test 582 run properly.

3 files changed, 34 insertions, 15 deletions

diff --git a/lib/multi.c b/lib/multi.c
index 91d92df90..d68c368f3 100644
--- a/lib/multi.c
+++ b/lib/multi.c
@@ -2105,35 +2105,41 @@ static CURLMcode multi_socket(struct Curl_multi *multi,
          and just move on. */
       ;
     else {
+      struct connectdata *conn;
       data = entry->easy;
 
       if(data->magic != CURLEASY_MAGIC_NUMBER)
         /* bad bad bad bad bad bad bad */
         return CURLM_INTERNAL_ERROR;
 
+      /* note that this can possibly be NULL at this point */
+      conn = data->set.one_easy->easy_conn;
+
       /* If the pipeline is enabled, take the handle which is in the head of
          the pipeline. If we should write into the socket, take the send_pipe
          head.  If we should read from the socket, take the recv_pipe head. */
-      if(data->set.one_easy->easy_conn) {
+      if(conn) {
         if ((ev_bitmask & CURL_POLL_OUT) &&
-            data->set.one_easy->easy_conn->send_pipe &&
-            data->set.one_easy->easy_conn->send_pipe->head)
-          data = data->set.one_easy->easy_conn->send_pipe->head->ptr;
+            conn->send_pipe &&
+            conn->send_pipe->head)
+          data = conn->send_pipe->head->ptr;
         else if ((ev_bitmask & CURL_POLL_IN) &&
-                 data->set.one_easy->easy_conn->recv_pipe &&
-                 data->set.one_easy->easy_conn->recv_pipe->head)
-          data = data->set.one_easy->easy_conn->recv_pipe->head->ptr;
+                 conn->recv_pipe &&
+                 conn->recv_pipe->head)
+          data = conn->recv_pipe->head->ptr;
       }
 
-      if(data->set.one_easy->easy_conn)  /* set socket event bitmask */
-        data->set.one_easy->easy_conn->cselect_bits = ev_bitmask;
+      if(conn && !(conn->handler->protocol & PROT_LOCKEDBITS))
+        /* set socket event bitmask if they're not locked */
+        conn->cselect_bits = ev_bitmask;
 
       do
         result = multi_runsingle(multi, now, data->set.one_easy);
       while (CURLM_CALL_MULTI_PERFORM == result);
 
-      if(data->set.one_easy->easy_conn)
-        data->set.one_easy->easy_conn->cselect_bits = 0;
+      if(conn && !(conn->handler->protocol & PROT_LOCKEDBITS))
+        /* clear the bitmask only if not locked */
+        conn->cselect_bits = 0;
 
       if(CURLM_OK >= result)
         /* get the socket(s) and check if the state has been changed since
diff --git a/lib/ssh.c b/lib/ssh.c
index 118611efc..e85ad2631 100644
--- a/lib/ssh.c
+++ b/lib/ssh.c
@@ -2028,8 +2028,9 @@ static CURLcode ssh_statemach_act(struct connectdata *conn, bool *block)
       /* not set by Curl_setup_transfer to preserve keepon bits */
       conn->writesockfd = conn->sockfd;
 
-      /* FIXME: here should be explained why we need it to start the
-       * download */
+      /* we want to use the _receiving_ function even when the socket turns
+         out writableable as the underlying libssh2 recv function will deal
+         with both accordingly */
       conn->cselect_bits = CURL_CSELECT_IN;
     }
     if(result) {
@@ -2161,6 +2162,11 @@ static CURLcode ssh_statemach_act(struct connectdata *conn, bool *block)
         sshc->actualcode = result;
       }
       else {
+        /* we want to use the _sending_ function even when the socket turns
+           out readable as the underlying libssh2 scp send function will deal
+           with both accordingly */
+        conn->cselect_bits = CURL_CSELECT_OUT;
+
         state(conn, SSH_STOP);
       }
       break;
@@ -2207,8 +2213,9 @@ static CURLcode ssh_statemach_act(struct connectdata *conn, bool *block)
       /* not set by Curl_setup_transfer to preserve keepon bits */
       conn->writesockfd = conn->sockfd;
 
-      /* FIXME: here should be explained why we need it to start the
-       * download */
+      /* we want to use the _receiving_ function even when the socket turns
+         out writableable as the underlying libssh2 recv function will deal
+         with both accordingly */
       conn->cselect_bits = CURL_CSELECT_IN;
 
       if(result) {
diff --git a/lib/urldata.h b/lib/urldata.h
index 1d27d2626..2f7fe5e41 100644
--- a/lib/urldata.h
+++ b/lib/urldata.h
@@ -775,6 +775,12 @@ struct connectdata {
                           PROT_SFTP | PROT_SCP)
 #define PROT_DUALCHANNEL PROT_FTP /* these protocols use two connections */
 
+/* some protocols will have to call the underlying functions without regard to
+   what exact state the socket signals. IE even if the socket says "readable",
+   the send function might need to be called while uploading, or vice versa.
+*/
+#define PROT_LOCKEDBITS (PROT_SCP | PROT_SFTP)
+
   /* 'dns_entry' is the particular host we use. This points to an entry in the
      DNS cache and it will not get pruned while locked. It gets unlocked in
      Curl_done(). This entry will be NULL if the connection is re-used as then