Bug#31691: apt ftp bug fix

[nascheme]

Here is my humble patch...

--- ftplib.cc.dist      Thu Jul 30 23:57:02 1998
+++ ftplib.cc   Mon Jan 11 00:51:50 1999
@@ -405,7 +405,11 @@
     sin.sin_family = AF_INET;
     lhost = strdup(host);
     pnum = strchr(lhost,':');
-    if (pnum == NULL)
+    if (pnum != NULL)
+    {
+       *pnum = '\0';
+    }
+    if (pnum == NULL || pnum[1] == '\0')
     {
 #if defined(VMS)
        sin.sin_port = htons(21);
@@ -420,12 +424,16 @@
     }
     else
     {
-       *pnum++ = '\0';
+       pnum++;
        if (isdigit(*pnum))
            sin.sin_port = htons(atoi(pnum));
        else
        {
-           pse = getservbyname(pnum,"tcp");
+           if ((pse = getservbyname(pnum,"tcp")) == NULL)
+           {
+               if(ftplib_debug > 1) perror("getservbyname");
+               return 0;
+           }
            sin.sin_port = pse->s_port;
        }
     }