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.

9 files changed, 84 insertions, 29 deletions

diff --git a/lib/connect.c b/lib/connect.c
index 203345b92..5d48bbf71 100644
--- a/lib/connect.c
+++ b/lib/connect.c
@@ -238,7 +238,7 @@ long Curl_timeleft(struct SessionHandle *data,
 }
 
 static CURLcode bindlocal(struct connectdata *conn,
-                          curl_socket_t sockfd, int af)
+                          curl_socket_t sockfd, int af, unsigned int scope)
 {
   struct SessionHandle *data = conn->data;
 
@@ -286,7 +286,8 @@ static CURLcode bindlocal(struct connectdata *conn,
 
     /* interface */
     if(!is_host) {
-      switch(Curl_if2ip(af, conn->scope, dev, myhost, sizeof(myhost))) {
+      switch(Curl_if2ip(af, scope, conn->scope_id, dev,
+                        myhost, sizeof(myhost))) {
         case IF2IP_NOT_FOUND:
           if(is_interface) {
             /* Do not fall back to treating it as a host name */
@@ -1043,7 +1044,8 @@ static CURLcode singleipconnect(struct connectdata *conn,
 
   /* possibly bind the local end to an IP, interface or port */
   if(addr.family == AF_INET || addr.family == AF_INET6) {
-    result = bindlocal(conn, sockfd, addr.family);
+    result = bindlocal(conn, sockfd, addr.family,
+                       Curl_ipv6_scope((struct sockaddr*)&addr.sa_addr));
     if(result) {
       Curl_closesocket(conn, sockfd); /* close socket and bail out */
       if(result == CURLE_UNSUPPORTED_PROTOCOL) {
@@ -1319,9 +1321,9 @@ CURLcode Curl_socket(struct connectdata *conn,
     return CURLE_COULDNT_CONNECT;
 
 #if defined(ENABLE_IPV6) && defined(HAVE_SOCKADDR_IN6_SIN6_SCOPE_ID)
-  if(conn->scope && (addr->family == AF_INET6)) {
+  if(conn->scope_id && (addr->family == AF_INET6)) {
     struct sockaddr_in6 * const sa6 = (void *)&addr->sa_addr;
-    sa6->sin6_scope_id = conn->scope;
+    sa6->sin6_scope_id = conn->scope_id;
   }
 #endif
 
diff --git a/lib/ftp.c b/lib/ftp.c
index 34964d6b0..3eabec08c 100644
--- a/lib/ftp.c
+++ b/lib/ftp.c
@@ -1079,8 +1079,9 @@ static CURLcode ftp_state_use_port(struct connectdata *conn,
 
     if(*addr != '\0') {
       /* attempt to get the address of the given interface name */
-      switch(Curl_if2ip(conn->ip_addr->ai_family, conn->scope, addr,
-                     hbuf, sizeof(hbuf))) {
+      switch(Curl_if2ip(conn->ip_addr->ai_family,
+                        Curl_ipv6_scope(conn->ip_addr->ai_addr),
+                        conn->scope_id, addr, hbuf, sizeof(hbuf))) {
         case IF2IP_NOT_FOUND:
           /* not an interface, use the given string as host name instead */
           host = addr;
diff --git a/lib/if2ip.c b/lib/if2ip.c
index 05ae7d6f8..6fc09ec63 100644
--- a/lib/if2ip.c
+++ b/lib/if2ip.c
@@ -5,7 +5,7 @@
  *                            | (__| |_| |  _ <| |___
  *                             \___|\___/|_| \_\_____|
  *
- * Copyright (C) 1998 - 2013, Daniel Stenberg, <daniel@haxx.se>, et al.
+ * Copyright (C) 1998 - 2014, Daniel Stenberg, <daniel@haxx.se>, et al.
  *
  * This software is licensed as described in the file COPYING, which
  * you should have received as part of this distribution. The terms
@@ -63,6 +63,38 @@
 
 /* ------------------------------------------------------------------ */
 
+/* Return the scope of the given address. */
+unsigned int Curl_ipv6_scope(const struct sockaddr *sa)
+{
+#ifndef ENABLE_IPV6
+  (void) sa;
+#else
+  if(sa->sa_family == AF_INET6) {
+    const struct sockaddr_in6 * sa6 = (const struct sockaddr_in6 *) sa;
+    const unsigned char * b = sa6->sin6_addr.s6_addr;
+    unsigned short w = (unsigned short) ((b[0] << 8) | b[1]);
+
+    switch(w & 0xFFC0) {
+    case 0xFE80:
+      return IPV6_SCOPE_LINKLOCAL;
+    case 0xFEC0:
+      return IPV6_SCOPE_SITELOCAL;
+    case 0x0000:
+      w = b[1] | b[2] | b[3] | b[4] | b[5] | b[6] | b[7] | b[8] | b[9] |
+          b[10] | b[11] | b[12] | b[13] | b[14];
+      if(w || b[15] != 0x01)
+        break;
+      return IPV6_SCOPE_NODELOCAL;
+    default:
+      break;
+    }
+  }
+#endif
+
+  return IPV6_SCOPE_GLOBAL;
+}
+
+
 #if defined(HAVE_GETIFADDRS)
 
 bool Curl_if_is_interface_name(const char *interf)
@@ -84,7 +116,8 @@ bool Curl_if_is_interface_name(const char *interf)
 }
 
 if2ip_result_t Curl_if2ip(int af, unsigned int remote_scope,
-                          const char *interf, char *buf, int buf_size)
+                          unsigned int remote_scope_id, const char *interf,
+                          char *buf, int buf_size)
 {
   struct ifaddrs *iface, *head;
   if2ip_result_t res = IF2IP_NOT_FOUND;
@@ -105,20 +138,29 @@ if2ip_result_t Curl_if2ip(int af, unsigned int remote_scope,
 #ifdef ENABLE_IPV6
             if(af == AF_INET6) {
               unsigned int scopeid = 0;
+              unsigned int ifscope = Curl_ipv6_scope(iface->ifa_addr);
+
+              if(ifscope != remote_scope) {
+                /* We are interested only in interface addresses whose
+                   scope matches the remote address we want to
+                   connect to: global for global, link-local for
+                   link-local, etc... */
+                if(res == IF2IP_NOT_FOUND) res = IF2IP_AF_NOT_SUPPORTED;
+                continue;
+              }
+
               addr = &((struct sockaddr_in6 *)iface->ifa_addr)->sin6_addr;
 #ifdef HAVE_SOCKADDR_IN6_SIN6_SCOPE_ID
               /* Include the scope of this interface as part of the address */
               scopeid =
                 ((struct sockaddr_in6 *)iface->ifa_addr)->sin6_scope_id;
-#endif
-              if(scopeid != remote_scope) {
-                /* We are interested only in interface addresses whose
-                   scope ID matches the remote address we want to
-                   connect to: global (0) for global, link-local for
-                   link-local, etc... */
+
+              /* If given, scope id should match. */
+              if(remote_scope_id && scopeid != remote_scope_id) {
                 if(res == IF2IP_NOT_FOUND) res = IF2IP_AF_NOT_SUPPORTED;
                 continue;
               }
+#endif
               if(scopeid)
                 snprintf(scope, sizeof(scope), "%%%u", scopeid);
             }
@@ -154,7 +196,8 @@ bool Curl_if_is_interface_name(const char *interf)
 }
 
 if2ip_result_t Curl_if2ip(int af, unsigned int remote_scope,
-                          const char *interf, char *buf, int buf_size)
+                          unsigned int remote_scope_id, const char *interf,
+                          char *buf, int buf_size)
 {
   struct ifreq req;
   struct in_addr in;
@@ -163,6 +206,7 @@ if2ip_result_t Curl_if2ip(int af, unsigned int remote_scope,
   size_t len;
 
   (void)remote_scope;
+  (void)remote_scope_id;
 
   if(!interf || (af != AF_INET))
     return IF2IP_NOT_FOUND;
@@ -205,10 +249,12 @@ bool Curl_if_is_interface_name(const char *interf)
 }
 
 if2ip_result_t Curl_if2ip(int af, unsigned int remote_scope,
-                          const char *interf, char *buf, int buf_size)
+                          unsigned int remote_scope_id, const char *interf,
+                          char *buf, int buf_size)
 {
     (void) af;
     (void) remote_scope;
+    (void) remote_scope_id;
     (void) interf;
     (void) buf;
     (void) buf_size;
diff --git a/lib/if2ip.h b/lib/if2ip.h
index ac5875237..78bb0bd59 100644
--- a/lib/if2ip.h
+++ b/lib/if2ip.h
@@ -7,7 +7,7 @@
  *                            | (__| |_| |  _ <| |___
  *                             \___|\___/|_| \_\_____|
  *
- * Copyright (C) 1998 - 2012, Daniel Stenberg, <daniel@haxx.se>, et al.
+ * Copyright (C) 1998 - 2014, Daniel Stenberg, <daniel@haxx.se>, et al.
  *
  * This software is licensed as described in the file COPYING, which
  * you should have received as part of this distribution. The terms
@@ -23,6 +23,14 @@
  ***************************************************************************/
 #include "curl_setup.h"
 
+/* IPv6 address scopes. */
+#define IPV6_SCOPE_GLOBAL       0       /* Global scope. */
+#define IPV6_SCOPE_LINKLOCAL    1       /* Link-local scope. */
+#define IPV6_SCOPE_SITELOCAL    2       /* Site-local scope (deprecated). */
+#define IPV6_SCOPE_NODELOCAL    3       /* Loopback. */
+
+unsigned int Curl_ipv6_scope(const struct sockaddr *sa);
+
 bool Curl_if_is_interface_name(const char *interf);
 
 typedef enum {
@@ -32,7 +40,8 @@ typedef enum {
 } if2ip_result_t;
 
 if2ip_result_t Curl_if2ip(int af, unsigned int remote_scope,
-                          const char *interf, char *buf, int buf_size);
+                          unsigned int remote_scope_id, const char *interf,
+                          char *buf, int buf_size);
 
 #ifdef __INTERIX
 
diff --git a/lib/imap.c b/lib/imap.c
index cd96cd804..86cfcf51e 100644
--- a/lib/imap.c
+++ b/lib/imap.c
@@ -61,7 +61,6 @@
 #include <curl/curl.h>
 #include "urldata.h"
 #include "sendf.h"
-#include "if2ip.h"
 #include "hostip.h"
 #include "progress.h"
 #include "transfer.h"
diff --git a/lib/pop3.c b/lib/pop3.c
index 9c6cc8b36..66004599a 100644
--- a/lib/pop3.c
+++ b/lib/pop3.c
@@ -63,7 +63,6 @@
 #include <curl/curl.h>
 #include "urldata.h"
 #include "sendf.h"
-#include "if2ip.h"
 #include "hostip.h"
 #include "progress.h"
 #include "transfer.h"
diff --git a/lib/smtp.c b/lib/smtp.c
index 4016741dc..7bd5158bf 100644
--- a/lib/smtp.c
+++ b/lib/smtp.c
@@ -62,7 +62,6 @@
 #include <curl/curl.h>
 #include "urldata.h"
 #include "sendf.h"
-#include "if2ip.h"
 #include "hostip.h"
 #include "progress.h"
 #include "transfer.h"
diff --git a/lib/url.c b/lib/url.c
index 5b7870f32..cbc750904 100644
--- a/lib/url.c
+++ b/lib/url.c
@@ -2369,7 +2369,7 @@ CURLcode Curl_setopt(struct SessionHandle *data, CURLoption option,
      * know that an unsigned int will always hold the value so we blindly
      * typecast to this type
      */
-    data->set.scope = curlx_sltoui(va_arg(param, long));
+    data->set.scope_id = curlx_sltoui(va_arg(param, long));
     break;
 
   case CURLOPT_PROTOCOLS:
@@ -4094,7 +4094,7 @@ static CURLcode parseurlandfillconn(struct SessionHandle *data,
         /* The address scope was well formed.  Knock it out of the
            hostname. */
         memmove(percent, endp, strlen(endp)+1);
-        conn->scope = (unsigned int)scope;
+        conn->scope_id = (unsigned int)scope;
       }
       else {
         /* Zone identifier is not numeric */
@@ -4120,7 +4120,7 @@ static CURLcode parseurlandfillconn(struct SessionHandle *data,
           memmove(percent,
                   percent + identifier_offset + strlen(ifname),
                   identifier_offset + strlen(ifname));
-          conn->scope = scopeidx;
+          conn->scope_id = scopeidx;
         }
         else
 #endif /* HAVE_NET_IF_H && IFNAMSIZ */
@@ -4129,9 +4129,9 @@ static CURLcode parseurlandfillconn(struct SessionHandle *data,
     }
   }
 
-  if(data->set.scope)
+  if(data->set.scope_id)
     /* Override any scope that was set above.  */
-    conn->scope = data->set.scope;
+    conn->scope_id = data->set.scope_id;
 
   /* Remove the fragment part of the path. Per RFC 2396, this is always the
      last part of the URI. We are looking for the first '#' so that we deal
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)