FTP: fix IPv6 host using link-local address

... and make sure we can connect the data connection to a host name that
is longer than 48 bytes.

Also simplifies the code somewhat by re-using the original host name
more, as it is likely still in the DNS cache.

Original-Patch-by: Vojtěch Král
Bug: http://curl.haxx.se/bug/view.cgi?id=1468

2 files changed, 28 insertions, 39 deletions

diff --git a/lib/ftp.c b/lib/ftp.c
index 2f4351e0c..528b4c13c 100644
--- a/lib/ftp.c
+++ b/lib/ftp.c
@@ -5,7 +5,7 @@
  *                            | (__| |_| |  _ <| |___
  *                             \___|\___/|_| \_\_____|
  *
- * Copyright (C) 1998 - 2014, Daniel Stenberg, <daniel@haxx.se>, et al.
+ * Copyright (C) 1998 - 2015, Daniel Stenberg, <daniel@haxx.se>, et al.
  *
  * This software is licensed as described in the file COPYING, which
  * you should have received as part of this distribution. The terms
@@ -294,10 +294,10 @@ static void freedirs(struct ftp_conn *ftpc)
     ftpc->dirs = NULL;
     ftpc->dirdepth = 0;
   }
-  if(ftpc->file) {
-    free(ftpc->file);
-    ftpc->file = NULL;
-  }
+  Curl_safefree(ftpc->file);
+
+  /* no longer of any use */
+  Curl_safefree(ftpc->newhost);
 }
 
 /* Returns non-zero if the given string contains CR (\r) or LF (\n),
@@ -1917,6 +1917,9 @@ static CURLcode ftp_state_pasv_resp(struct connectdata *conn,
   unsigned short connectport; /* the local port connect() should use! */
   char *str=&data->state.buffer[4];  /* start on the first letter */
 
+  /* if we come here again, make sure the former name is cleared */
+  Curl_safefree(ftpc->newhost);
+
   if((ftpc->count1 == 0) &&
      (ftpcode == 229)) {
     /* positive EPSV response */
@@ -1949,18 +1952,10 @@ static CURLcode ftp_state_pasv_resp(struct connectdata *conn,
         if(ptr) {
           ftpc->newport = (unsigned short)(num & 0xffff);
 
-          if(conn->bits.tunnel_proxy ||
-             conn->proxytype == CURLPROXY_SOCKS5 ||
-             conn->proxytype == CURLPROXY_SOCKS5_HOSTNAME ||
-             conn->proxytype == CURLPROXY_SOCKS4 ||
-             conn->proxytype == CURLPROXY_SOCKS4A)
-            /* proxy tunnel -> use other host info because ip_addr_str is the
-               proxy address not the ftp host */
-            snprintf(ftpc->newhost, sizeof(ftpc->newhost), "%s",
-                     conn->host.name);
-          else
-            /* use the same IP we are already connected to */
-            snprintf(ftpc->newhost, NEWHOST_BUFSIZE, "%s", conn->ip_addr_str);
+          /* use the original host name again */
+          ftpc->newhost = strdup(conn->host.name);
+          if(!ftpc->newhost)
+            return CURLE_OUT_OF_MEMORY;
         }
       }
       else
@@ -2001,26 +1996,21 @@ static CURLcode ftp_state_pasv_resp(struct connectdata *conn,
 
     /* we got OK from server */
     if(data->set.ftp_skip_ip) {
-      /* told to ignore the remotely given IP but instead use the one we used
+      /* told to ignore the remotely given IP but instead use the host we used
          for the control connection */
-      infof(data, "Skips %d.%d.%d.%d for data connection, uses %s instead\n",
+      infof(data, "Skip %d.%d.%d.%d for data connection, re-use %s instead\n",
             ip[0], ip[1], ip[2], ip[3],
-            conn->ip_addr_str);
-      if(conn->bits.tunnel_proxy ||
-         conn->proxytype == CURLPROXY_SOCKS5 ||
-         conn->proxytype == CURLPROXY_SOCKS5_HOSTNAME ||
-         conn->proxytype == CURLPROXY_SOCKS4 ||
-         conn->proxytype == CURLPROXY_SOCKS4A)
-        /* proxy tunnel -> use other host info because ip_addr_str is the
-           proxy address not the ftp host */
-        snprintf(ftpc->newhost, sizeof(ftpc->newhost), "%s", conn->host.name);
-      else
-        snprintf(ftpc->newhost, sizeof(ftpc->newhost), "%s",
-                 conn->ip_addr_str);
+            conn->host.name);
+
+      /* use the original host name again */
+      ftpc->newhost = strdup(conn->host.name);
     }
     else
-      snprintf(ftpc->newhost, sizeof(ftpc->newhost),
-               "%d.%d.%d.%d", ip[0], ip[1], ip[2], ip[3]);
+      ftpc->newhost = aprintf("%d.%d.%d.%d", ip[0], ip[1], ip[2], ip[3]);
+
+    if(!ftpc->newhost)
+      return CURLE_OUT_OF_MEMORY;
+
     ftpc->newport = (unsigned short)(((port[0]<<8) + port[1]) & 0xffff);
   }
   else if(ftpc->count1 == 0) {
diff --git a/lib/ftp.h b/lib/ftp.h
index b6bfc0287..833447bcb 100644
--- a/lib/ftp.h
+++ b/lib/ftp.h
@@ -7,7 +7,7 @@
  *                            | (__| |_| |  _ <| |___
  *                             \___|\___/|_| \_\_____|
  *
- * Copyright (C) 1998 - 2013, Daniel Stenberg, <daniel@haxx.se>, et al.
+ * Copyright (C) 1998 - 2015, Daniel Stenberg, <daniel@haxx.se>, et al.
  *
  * This software is licensed as described in the file COPYING, which
  * you should have received as part of this distribution. The terms
@@ -147,11 +147,10 @@ struct ftp_conn {
   curl_off_t known_filesize; /* file size is different from -1, if wildcard
                                 LIST parsing was done and wc_statemach set
                                 it */
-  /* newhost must be able to hold a full IP-style address in ASCII, which
-     in the IPv6 case means 5*8-1 = 39 letters */
-#define NEWHOST_BUFSIZE 48
-  char newhost[NEWHOST_BUFSIZE]; /* this is the pair to connect the DATA... */
-  unsigned short newport;        /* connection to */
+  /* newhost is the (allocated) IP addr or host name to connect the data
+     connection to */
+  char *newhost;          /* this is the pair to connect the DATA... */
+  unsigned short newport; /* connection to */
 
 };