Netif (Linux): support default route detection for ipv6

Author: CarterLi

src/common/netif/netif_linux.c

@@ -7,20 +7,46 @@
 #define FF_STR_INDIR(x) #x
 #define FF_STR(x) FF_STR_INDIR(x)
 
-bool ffNetifGetDefaultRouteImpl(char iface[IF_NAMESIZE + 1], uint32_t* ifIndex)
+static bool getDefaultRouteIPv4(char iface[IF_NAMESIZE + 1], uint32_t* ifIndex)
 {
     FILE* FF_AUTO_CLOSE_FILE netRoute = fopen("/proc/net/route", "r");
     if (!netRoute) return false;
 
     // skip first line
     FF_UNUSED(fscanf(netRoute, "%*[^\n]\n"));
 
-    unsigned long long destination; //, gateway, flags, refCount, use, metric, mask, mtu,
+    unsigned long long destination; //, gateway, flags, refCount, use, metric, mask, mtu, ...
     while (fscanf(netRoute, "%" FF_STR(IF_NAMESIZE) "s%llx%*[^\n]", iface, &destination) == 2)
     {
         if (destination != 0) continue;
         *ifIndex = if_nametoindex(iface);
         return true;
     }
+    iface[0] = '\0';
     return false;
 }
+
+static bool getDefaultRouteIPv6(char iface[IF_NAMESIZE + 1], uint32_t* ifIndex)
+{
+    FILE* FF_AUTO_CLOSE_FILE netRoute = fopen("/proc/net/ipv6_route", "r");
+    if (!netRoute) return false;
+
+    uint32_t prefixLen;
+    //destination, dest_prefix_len, source, src_prefix_len, next hop, metric, ref counter, use counter, flags, iface
+    while (fscanf(netRoute, "%*s %x %*s %*s %*s %*s %*s %*s %*s %" FF_STR(IF_NAMESIZE) "s", &prefixLen, iface) == 2)
+    {
+        if (prefixLen != 0) continue;
+        *ifIndex = if_nametoindex(iface);
+        return true;
+    }
+    iface[0] = '\0';
+    return false;
+}
+
+bool ffNetifGetDefaultRouteImpl(char iface[IF_NAMESIZE + 1], uint32_t* ifIndex)
+{
+    if (getDefaultRouteIPv4(iface, ifIndex))
+        return true;
+
+    return getDefaultRouteIPv6(iface, ifIndex);
+}