Kim Rinnewitz reported that --local-port didn't work with TFTP transfers.

This happened because the tftp code always uncondionally did a bind()
without caring if one already had been done and then it failed. I wrote a
test case (1009) to verify this, but it is a bit error-prone since it will
have to pick a fixed local port number and since the tests are run on so
many different hosts in different situations I add it in disabled state.

3 files changed, 7 insertions, 3 deletions

diff --git a/lib/connect.c b/lib/connect.c
index d386a1bc5..918602c2d 100644
--- a/lib/connect.c
+++ b/lib/connect.c
@@ -380,6 +380,7 @@ static CURLcode bindlocal(struct connectdata *conn,
         port = ntohs(((struct sockaddr_in6 *)&add)->sin6_port);
 #endif
       infof(data, "Local port: %d\n", port);
+      conn->bits.bound = TRUE;
       return CURLE_OK;
     }
     if(--portnum > 0) {
diff --git a/lib/tftp.c b/lib/tftp.c
index a3a69cf6c..938c2e239 100644
--- a/lib/tftp.c
+++ b/lib/tftp.c
@@ -598,9 +598,9 @@ CURLcode Curl_tftp_connect(struct connectdata *conn, bool *done)
 
   tftp_set_timeouts(state);
 
-  if(!conn->bits.reuse) {
-    /* If not reused, bind to any interface, random UDP port. If it is reused,
-     * this has already been done!
+  if(!conn->bits.bound) {
+    /* If not already bound, bind to any interface, random UDP port. If it is
+     * reused or a custom local port was desired, this has already been done!
      *
      * We once used the size of the local_addr struct as the third argument for
      * bind() to better work with IPv6 or whatever size the struct could have,
@@ -619,6 +619,7 @@ CURLcode Curl_tftp_connect(struct connectdata *conn, bool *done)
             Curl_strerror(conn, SOCKERRNO));
       return CURLE_COULDNT_CONNECT;
     }
+    conn->bits.bound = TRUE;
   }
 
   Curl_pgrsStartNow(conn->data);
diff --git a/lib/urldata.h b/lib/urldata.h
index 51844c4ba..52647a1cb 100644
--- a/lib/urldata.h
+++ b/lib/urldata.h
@@ -609,6 +609,8 @@ struct ConnectBits {
   bool proxy_connect_closed; /* set true if a proxy disconnected the
                                 connection in a CONNECT request with auth, so
                                 that libcurl should reconnect and continue. */
+  bool bound; /* set true if bind() has already been done on this socket/
+                 connection */
 };
 
 struct hostname {