1 files changed, 107 insertions, 0 deletions

diff --git a/common/socket.c b/common/socket.c
index cf6e9eb..6b4a596 100644
--- a/common/socket.c
+++ b/common/socket.c
@@ -43,6 +43,10 @@ static int wsa_init = 0;
 #include <netdb.h>
 #include <arpa/inet.h>
 #include <fcntl.h>
+#ifdef AF_INET6
+#include <net/if.h>
+#include <ifaddrs.h>
+#endif
 #endif
 #include "socket.h"
 
@@ -310,6 +314,97 @@ int socket_create(uint16_t port)
         return sfd;
 }
 
+#ifdef AF_INET6
+static uint32_t _in6_addr_scope(struct in6_addr* addr)
+{
+        uint32_t scope = 0;
+
+        if (IN6_IS_ADDR_MULTICAST(addr)) {
+                if (IN6_IS_ADDR_MC_NODELOCAL(addr)) {
+                        scope = 1;
+                } else if (IN6_IS_ADDR_MC_LINKLOCAL(addr)) {
+                        scope = 2;
+                } else if (IN6_IS_ADDR_MC_SITELOCAL(addr)) {
+                        scope = 3;
+                }
+
+                return scope;
+        }
+
+        if (IN6_IS_ADDR_LINKLOCAL(addr)) {
+                scope = 2;
+        } else if (IN6_IS_ADDR_SITELOCAL(addr)) {
+                scope = 3;
+        } else if (IN6_IS_ADDR_LOOPBACK(addr)) {
+                scope = 4;
+        } else if (IN6_IS_ADDR_UNSPECIFIED(addr)) {
+                scope = 0;
+        }
+
+        return scope;
+}
+
+static int32_t _in6_addr_scope_id(struct in6_addr* addr)
+{
+        int32_t res = -1;
+
+        struct ifaddrs *ifaddr, *ifa;
+        uint32_t addr_scope;
+
+        /* get scope for requested address */
+        addr_scope = _in6_addr_scope(addr);
+        if (addr_scope == 0) {
+                /* global scope doesn't need a specific scope id */
+                return addr_scope;
+        }
+
+        /* get interfaces */
+        if (getifaddrs(&ifaddr) == -1) {
+                perror("getifaddrs");
+                return res;
+        }
+
+        /* loop over interfaces */
+        for (ifa = ifaddr; ifa != NULL; ifa = ifa->ifa_next) {
+                /* skip if no address is available */
+                if (ifa->ifa_addr == NULL) {
+                        continue;
+                }
+
+                /* skip if wrong family */
+                if (ifa->ifa_addr->sa_family != AF_INET6) {
+                        continue;
+                }
+
+                /* skip if not up */
+                if ((ifa->ifa_flags & IFF_UP) == 0) {
+                        continue;
+                }
+
+                /* skip if not running */
+                if ((ifa->ifa_flags & IFF_RUNNING) == 0) {
+                        continue;
+                }
+
+                struct sockaddr_in6* addr_in = (struct sockaddr_in6*)ifa->ifa_addr;
+
+                /* skip if scopes do not match */
+                if (_in6_addr_scope(&addr_in->sin6_addr) != addr_scope) {
+                        continue;
+                }
+
+                /* use the scope id of this interface */
+                res = addr_in->sin6_scope_id;
+
+                break;
+        }
+
+        freeifaddrs(ifaddr);
+
+        return res;
+}
+#endif
+
 int socket_connect_addr(struct sockaddr* addr, uint16_t port)
 {
         int sfd = -1;
@@ -337,6 +432,18 @@ int socket_connect_addr(struct sockaddr* addr, uint16_t port)
         else if (addr->sa_family == AF_INET6) {
                 struct sockaddr_in6* addr_in = (struct sockaddr_in6*)addr;
                 addr_in->sin6_port = htons(port);
+
+                /*
+                 * IPv6 Routing Magic:
+                 *
+                 * If the scope of the address is a link-local one, IPv6 requires the
+                 * scope id set to an interface number to allow proper routing. However,
+                 * as the provided sockaddr might contain a wrong scope id, we must find
+                 * a scope id from a suitable interface on this system or routing might
+                 * fail. An IPv6 guru should have another look though...
+                 */
+                addr_in->sin6_scope_id = _in6_addr_scope_id(&addr_in->sin6_addr);
+
                 addrlen = sizeof(struct sockaddr_in6);
         }
 #endif