IPV6: address scope != scope id

There was a confusion between these: this commit tries to disambiguate them.
- Scope can be computed from the address itself.
- Scope id is scope dependent: it is currently defined as 1-based local
  interface index for link-local scoped addresses, and as a site index(?) for
  (obsolete) site-local addresses. Linux only supports it for link-local
  addresses.
The URL parser properly parses a scope id as an interface index, but stores it
in a field named "scope": confusion. The field has been renamed into "scope_id".
Curl_if2ip() used the scope id as it was a scope. This caused failures
to bind to an interface.
Scope is now computed from the addresses and Curl_if2ip() matches them.
If redundantly specified in the URL, scope id is check for mismatch with
the interface index.

This commit should fix SF bug #1451.

1 files changed, 2 insertions, 2 deletions

diff --git a/lib/urldata.h b/lib/urldata.h
index a2dc1c362..79fcd9a4d 100644
--- a/lib/urldata.h
+++ b/lib/urldata.h
@@ -894,7 +894,7 @@ struct connectdata {
      the ip_addr itself. */
   char ip_addr_str[MAX_IPADR_LEN];
 
-  unsigned int scope;    /* address scope for IPv6 */
+  unsigned int scope_id;  /* Scope id for IPv6 */
 
   int socktype;  /* SOCK_STREAM or SOCK_DGRAM */
 
@@ -1618,7 +1618,7 @@ struct UserDefined {
   bool proxy_transfer_mode; /* set transfer mode (;type=<a|i>) when doing FTP
                                via an HTTP proxy */
   char *str[STRING_LAST]; /* array of strings, pointing to allocated memory */
-  unsigned int scope;    /* address scope for IPv6 */
+  unsigned int scope_id;  /* Scope id for IPv6 */
   long allowed_protocols;
   long redir_protocols;
 #if defined(HAVE_GSSAPI) || defined(USE_WINDOWS_SSPI)