ftp: separate FTPS from FTP over "HTTPS proxy"

When using HTTPS proxy, SSL is used but not in the view of the FTP
protocol handler itself so separate the connection's use of SSL from the
FTP control connection's sue.

Reported-by: Mingtao Yang
Fixes #5523
Closes #6006

lib/ftp.c

@@ -2508,7 +2508,7 @@ static CURLcode ftp_state_loggedin(struct connectdata *conn)
 {
   CURLcode result = CURLE_OK;
 
-  if(conn->ssl[FIRSTSOCKET].use) {
+  if(conn->bits.ftp_use_control_ssl) {
     /* PBSZ = PROTECTION BUFFER SIZE.
 
     The 'draft-murray-auth-ftp-ssl' (draft 12, page 7) says:
@@ -2659,14 +2659,8 @@ static CURLcode ftp_statemach_act(struct connectdata *conn)
       }
 #endif
 
-      if(data->set.use_ssl &&
-         (!conn->ssl[FIRSTSOCKET].use
-#ifndef CURL_DISABLE_PROXY
-          || (conn->bits.proxy_ssl_connected[FIRSTSOCKET] &&
-              !conn->proxy_ssl[FIRSTSOCKET].use)
-#endif
-           )) {
-        /* We don't have a SSL/TLS connection yet, but FTPS is
+      if(data->set.use_ssl && !conn->bits.ftp_use_control_ssl) {
+        /* We don't have a SSL/TLS control connection yet, but FTPS is
            requested. Try a FTPS connection now */
 
         ftpc->count3 = 0;
@@ -2708,6 +2702,7 @@ static CURLcode ftp_statemach_act(struct connectdata *conn)
         result = Curl_ssl_connect(conn, FIRSTSOCKET);
         if(!result) {
           conn->bits.ftp_use_data_ssl = FALSE; /* clear-text data */
+          conn->bits.ftp_use_control_ssl = TRUE; /* SSL on control */
           result = ftp_state_user(conn);
         }
       }
@@ -3089,7 +3084,7 @@ static CURLcode ftp_block_statemach(struct connectdata *conn)
  *
  */
 static CURLcode ftp_connect(struct connectdata *conn,
-                                 bool *done) /* see description above */
+                            bool *done) /* see description above */
 {
   CURLcode result;
   struct ftp_conn *ftpc = &conn->proto.ftpc;
@@ -3110,6 +3105,7 @@ static CURLcode ftp_connect(struct connectdata *conn,
     result = Curl_ssl_connect(conn, FIRSTSOCKET);
     if(result)
       return result;
+    conn->bits.ftp_use_control_ssl = TRUE;
   }
 
   Curl_pp_setup(pp); /* once per transfer */

lib/urldata.h

@@ -469,6 +469,7 @@ struct ConnectBits {
                          EPRT doesn't work we disable it for the forthcoming
                          requests */
   BIT(ftp_use_data_ssl); /* Enabled SSL for the data connection */
+  BIT(ftp_use_control_ssl); /* Enabled SSL for the control connection */
 #endif
   BIT(netrc);         /* name+password provided by netrc */
   BIT(bound); /* set true if bind() has already been done on this socket/

tests/data/test1631

@@ -74,8 +74,6 @@ Proxy-Connection: Keep-Alive
 <protocol>
 USER anonymous
 PASS ftp@example.com
-PBSZ 0
-PROT P
 PWD
 EPSV
 TYPE I

tests/data/test1632

@@ -89,8 +89,6 @@ Proxy-Connection: Keep-Alive
 <protocol>
 USER anonymous
 PASS ftp@example.com
-PBSZ 0
-PROT P
 PWD
 EPSV
 TYPE I