lib: Prefix URLs with lower-case protocol names/schemes

Before this patch, if a URL does not start with the protocol
name/scheme, effective URLs would be prefixed with upper-case protocol
names/schemes. This behavior might not be expected by library users or
end users.

For example, if `CURLOPT_DEFAULT_PROTOCOL` is set to "https". And the
URL is "hostname/path". The effective URL would be
"HTTPS://hostname/path" instead of "https://hostname/path".

After this patch, effective URLs would be prefixed with a lower-case
protocol name/scheme.

Closes #597

Signed-off-by: Mohammad AlSaleh <CE.Mohammad.AlSaleh@gmail.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/lib/url.c b/lib/url.c
index eaa282a04..2fd0a1283 100644
--- a/lib/url.c
+++ b/lib/url.c
@@ -5511,6 +5511,7 @@ static CURLcode create_conn(struct SessionHandle *data,
        we're gonna follow a Location: later or... then we need the protocol
        part added so that we have a valid URL. */
     char *reurl;
+    char *ch_lower;
 
     reurl = aprintf("%s://%s", conn->handler->scheme, data->change.url);
 
@@ -5519,6 +5520,10 @@ static CURLcode create_conn(struct SessionHandle *data,
       goto out;
     }
 
+    /* Change protocol prefix to lower-case */
+    for(ch_lower = reurl; *ch_lower != ':'; ch_lower++)
+      *ch_lower = (char)TOLOWER(*ch_lower);
+
     if(data->change.url_alloc) {
       Curl_safefree(data->change.url);
       data->change.url_alloc = FALSE;