URL parser: allow URLs to use one, two or three slashes

Mostly in order to support broken web sites that redirect to broken URLs
that are accepted by browsers.

Browsers are typically even more leniant than this as the WHATWG URL
spec they should allow an _infinite_ amount. I tested 8000 slashes with
Firefox and it just worked.

Added test case 1141, 1142 and 1143 to verify the new parser.

Closes #791

1 files changed, 25 insertions, 5 deletions

diff --git a/lib/url.c b/lib/url.c
index 2a3026650..3f0bde258 100644
--- a/lib/url.c
+++ b/lib/url.c
@@ -4141,12 +4141,17 @@ static CURLcode parseurlandfillconn(struct SessionHandle *data,
   }
   else {
     /* clear path */
+    char slashbuf[4];
     path[0]=0;
 
-    if(2 > sscanf(data->change.url,
-                   "%15[^\n:]://%[^\n/?]%[^\n]",
-                   protobuf,
-                   conn->host.name, path)) {
+    rc = sscanf(data->change.url,
+                "%15[^\n:]:%3[/]%[^\n/?]%[^\n]",
+                protobuf, slashbuf, conn->host.name, path);
+    if(2 == rc) {
+      failf(data, "Bad URL");
+      return CURLE_URL_MALFORMAT;
+    }
+    if(3 > rc) {
 
       /*
        * The URL was badly formatted, let's try the browser-style _without_
@@ -4197,8 +4202,23 @@ static CURLcode parseurlandfillconn(struct SessionHandle *data,
 
       *prot_missing = TRUE; /* not given in URL */
     }
-    else
+    else {
+      size_t s = strlen(slashbuf);
       protop = protobuf;
+      if(s != 2) {
+        infof(data, "Unwillingly accepted illegal URL using %d slash%s!\n",
+              s, s>1?"es":"");
+
+        if(data->change.url_alloc)
+          free(data->change.url);
+        /* repair the URL to use two slashes */
+        data->change.url = aprintf("%s://%s%s",
+                                   protobuf, conn->host.name, path);
+        if(!data->change.url)
+          return CURLE_OUT_OF_MEMORY;
+        data->change.url_alloc = TRUE;
+      }
+    }
   }
 
   /* We search for '?' in the host name (but only on the right side of a