urlapi: add CURLU_GUESS_SCHEME and fix hostname acceptance

In order for this API to fully work for libcurl itself, it now offers a
CURLU_GUESS_SCHEME flag that makes it "guess" scheme based on the host
name prefix just like libcurl always did. If there's no known prefix, it
will guess "http://".

Separately, it relaxes the check of the host name so that IDN host names
can be passed in as well.

Both these changes are necessary for libcurl itself to use this API.

Assisted-by: Daniel Gustafsson
Closes #3018

1 files changed, 37 insertions, 11 deletions

diff --git a/lib/urlapi.c b/lib/urlapi.c
index f6d911667..ef565d98d 100644
--- a/lib/urlapi.c
+++ b/lib/urlapi.c
@@ -554,7 +554,7 @@ static CURLUcode junkscan(char *part)
 
 static CURLUcode hostname_check(char *hostname, unsigned int flags)
 {
-  const char *l; /* accepted characters */
+  const char *l = NULL; /* accepted characters */
   size_t len;
   size_t hlen = strlen(hostname);
   (void)flags;
@@ -564,14 +564,21 @@ static CURLUcode hostname_check(char *hostname, unsigned int flags)
     l = "0123456789abcdefABCDEF::.";
     hlen -= 2;
   }
-  else /* % for URL escaped letters */
-    l = "0123456789abcdefghijklimnopqrstuvwxyz-_.ABCDEFGHIJKLIMNOPQRSTUVWXYZ%";
-
-  len = strspn(hostname, l);
-  if(hlen != len)
-    /* hostname with bad content */
-    return CURLUE_MALFORMED_INPUT;
 
+  if(l) {
+    /* only valid letters are ok */
+    len = strspn(hostname, l);
+    if(hlen != len)
+      /* hostname with bad content */
+      return CURLUE_MALFORMED_INPUT;
+  }
+  else {
+    /* letters from the second string is not ok */
+    len = strcspn(hostname, " ");
+    if(hlen != len)
+      /* hostname with bad content */
+      return CURLUE_MALFORMED_INPUT;
+  }
   return CURLUE_OK;
 }
 
@@ -587,7 +594,7 @@ static CURLUcode seturl(const char *url, CURLU *u, unsigned int flags)
   CURLUcode result;
   bool url_has_scheme = FALSE;
   char schemebuf[MAX_SCHEME_LEN];
-  char *schemep;
+  char *schemep = NULL;
   size_t schemelen = 0;
   size_t urllen;
   const struct Curl_handler *h = NULL;
@@ -723,9 +730,10 @@ static CURLUcode seturl(const char *url, CURLU *u, unsigned int flags)
     else {
       /* no scheme! */
 
-      if(!(flags & CURLU_DEFAULT_SCHEME))
+      if(!(flags & (CURLU_DEFAULT_SCHEME|CURLU_GUESS_SCHEME)))
         return CURLUE_MALFORMED_INPUT;
-      schemep = (char *) DEFAULT_SCHEME;
+      if(flags & CURLU_DEFAULT_SCHEME)
+        schemep = (char *) DEFAULT_SCHEME;
 
       /*
        * The URL was badly formatted, let's try without scheme specified.
@@ -744,6 +752,24 @@ static CURLUcode seturl(const char *url, CURLU *u, unsigned int flags)
     memcpy(hostname, hostp, len);
     hostname[len] = 0;
 
+    if((flags & CURLU_GUESS_SCHEME) && !schemep) {
+      /* legacy curl-style guess based on host name */
+      if(checkprefix("ftp.", hostname))
+        schemep = (char *)"ftp";
+      else if(checkprefix("dict.", hostname))
+        schemep = (char *)"dict";
+      else if(checkprefix("ldap.", hostname))
+        schemep = (char *)"ldap";
+      else if(checkprefix("imap.", hostname))
+        schemep = (char *)"imap";
+      else if(checkprefix("smtp.", hostname))
+        schemep = (char *)"smtp";
+      else if(checkprefix("pop3.", hostname))
+        schemep = (char *)"pop3";
+      else
+        schemep = (char *)"http";
+    }
+
     len = strlen(p);
     memcpy(path, p, len);
     path[len] = 0;