ftp: prevent server from hanging on closed data connection

Some FTP servers (e.g. Pure-ftpd) end up hanging if we close the data
connection before transferring all the requested data.  If we send ABOR
in that case, it prevents the server from hanging.

Bug: https://bugzilla.redhat.com/643656
Reported by: Pasi Karkkainen, Patrick Monnerat

6 files changed, 11 insertions, 1 deletions

diff --git a/lib/ftp.c b/lib/ftp.c
index b5a4fd5be..679f2334c 100644
--- a/lib/ftp.c
+++ b/lib/ftp.c
@@ -3083,6 +3083,11 @@ static CURLcode ftp_done(struct connectdata *conn, CURLcode status,
 #endif
 
   if(conn->sock[SECONDARYSOCKET] != CURL_SOCKET_BAD) {
+    if(!result && ftpc->dont_check)
+      /* prevent some FTP servers (namely Pure-ftpd) from hanging if we close
+       * the data channel before transferring all data */
+      result = Curl_pp_sendf(&ftpc->pp, "ABOR");
+
     if(conn->ssl[SECONDARYSOCKET].use) {
       /* The secondary socket is using SSL so we must close down that part
          first before we close the socket for real */
@@ -3097,7 +3102,7 @@ static CURLcode ftp_done(struct connectdata *conn, CURLcode status,
     }
   }
 
-  if((ftp->transfer == FTPTRANSFER_BODY) && ftpc->ctl_valid &&
+  if(!result && (ftp->transfer == FTPTRANSFER_BODY) && ftpc->ctl_valid &&
      pp->pending_resp && !premature) {
     /*
      * Let's see what the server says about the transfer we just performed,
diff --git a/tests/data/test1036 b/tests/data/test1036
index b8ebc4fc0..a31cb458a 100644
--- a/tests/data/test1036
+++ b/tests/data/test1036
@@ -50,6 +50,7 @@ TYPE I
 SIZE 1036

 REST 20

 RETR 1036

+ABOR

 QUIT

 </protocol>
 <file name="log/curl1036.out">
diff --git a/tests/data/test1057 b/tests/data/test1057
index cfb88f2c5..b4ef20c8d 100644
--- a/tests/data/test1057
+++ b/tests/data/test1057
@@ -45,6 +45,7 @@ TYPE I
 SIZE 1057

 REST 52

 RETR 1057

+ABOR

 QUIT

 </protocol>
 </verify>
diff --git a/tests/data/test110 b/tests/data/test110
index b63ba8a2d..4a094e7e8 100644
--- a/tests/data/test110
+++ b/tests/data/test110
@@ -46,6 +46,7 @@ TYPE I
 SIZE 110

 REST 20

 RETR 110

+ABOR

 QUIT

 </protocol>
 </verify>
diff --git a/tests/data/test122 b/tests/data/test122
index fb1dd05fc..ac60672bb 100644
--- a/tests/data/test122
+++ b/tests/data/test122
@@ -39,6 +39,7 @@ EPSV
 PASV

 TYPE I

 SIZE 122

+ABOR

 QUIT

 </protocol>
 </verify>
diff --git a/tests/data/test135 b/tests/data/test135
index a051dba20..10eb0eacd 100644
--- a/tests/data/test135
+++ b/tests/data/test135
@@ -47,6 +47,7 @@ TYPE I
 SIZE 135

 REST 4

 RETR 135

+ABOR

 QUIT

 </protocol>
 </verify>