Avoid recursion in `ip_is_lan` and `ip_is_local`.

1 files changed, 54 insertions, 49 deletions

diff --git a/toxcore/LAN_discovery.c b/toxcore/LAN_discovery.c
index fd5bca34..aeeea566 100644
--- a/toxcore/LAN_discovery.c
+++ b/toxcore/LAN_discovery.c
@@ -272,71 +272,77 @@ static IP broadcast_ip(Family family_socket, Family family_broadcast)
     return ip;
 }
 
+static bool ip4_is_local(IP4 ip4)
+{
+    /* Loopback. */
+    return ip4.uint8[0] == 127;
+}
+
 /* Is IP a local ip or not. */
 bool ip_is_local(IP ip)
 {
     if (net_family_is_ipv4(ip.family)) {
-        IP4 ip4 = ip.ip.v4;
+        return ip4_is_local(ip.ip.v4);
+    }
 
-        /* Loopback. */
-        if (ip4.uint8[0] == 127) {
-            return 1;
-        }
-    } else {
-        /* embedded IPv4-in-IPv6 */
-        if (ipv6_ipv4_in_v6(ip.ip.v6)) {
-            IP ip4;
-            ip4.family = net_family_ipv4;
-            ip4.ip.v4.uint32 = ip.ip.v6.uint32[3];
-            return ip_is_local(ip4);
-        }
+    /* embedded IPv4-in-IPv6 */
+    if (ipv6_ipv4_in_v6(ip.ip.v6)) {
+        IP4 ip4;
+        ip4.uint32 = ip.ip.v6.uint32[3];
+        return ip4_is_local(ip4);
+    }
 
-        /* localhost in IPv6 (::1) */
-        if (ip.ip.v6.uint64[0] == 0 && ip.ip.v6.uint32[2] == 0 && ip.ip.v6.uint32[3] == net_htonl(1)) {
-            return 1;
-        }
+    /* localhost in IPv6 (::1) */
+    if (ip.ip.v6.uint64[0] == 0 && ip.ip.v6.uint32[2] == 0 && ip.ip.v6.uint32[3] == net_htonl(1)) {
+        return true;
     }
 
-    return 0;
+    return false;
 }
 
-bool ip_is_lan(IP ip)
+static bool ip4_is_lan(IP4 ip4)
 {
-    if (ip_is_local(ip)) {
+    /* 10.0.0.0 to 10.255.255.255 range. */
+    if (ip4.uint8[0] == 10) {
         return true;
     }
 
-    if (net_family_is_ipv4(ip.family)) {
-        IP4 ip4 = ip.ip.v4;
+    /* 172.16.0.0 to 172.31.255.255 range. */
+    if (ip4.uint8[0] == 172 && ip4.uint8[1] >= 16 && ip4.uint8[1] <= 31) {
+        return true;
+    }
 
-        /* 10.0.0.0 to 10.255.255.255 range. */
-        if (ip4.uint8[0] == 10) {
-            return true;
-        }
+    /* 192.168.0.0 to 192.168.255.255 range. */
+    if (ip4.uint8[0] == 192 && ip4.uint8[1] == 168) {
+        return true;
+    }
 
-        /* 172.16.0.0 to 172.31.255.255 range. */
-        if (ip4.uint8[0] == 172 && ip4.uint8[1] >= 16 && ip4.uint8[1] <= 31) {
-            return true;
-        }
+    /* 169.254.1.0 to 169.254.254.255 range. */
+    if (ip4.uint8[0] == 169 && ip4.uint8[1] == 254 && ip4.uint8[2] != 0
+            && ip4.uint8[2] != 255) {
+        return true;
+    }
 
-        /* 192.168.0.0 to 192.168.255.255 range. */
-        if (ip4.uint8[0] == 192 && ip4.uint8[1] == 168) {
-            return true;
-        }
+    /* RFC 6598: 100.64.0.0 to 100.127.255.255 (100.64.0.0/10)
+     * (shared address space to stack another layer of NAT) */
+    if ((ip4.uint8[0] == 100) && ((ip4.uint8[1] & 0xC0) == 0x40)) {
+        return true;
+    }
 
-        /* 169.254.1.0 to 169.254.254.255 range. */
-        if (ip4.uint8[0] == 169 && ip4.uint8[1] == 254 && ip4.uint8[2] != 0
-                && ip4.uint8[2] != 255) {
-            return true;
-        }
+    return false;
+}
 
-        /* RFC 6598: 100.64.0.0 to 100.127.255.255 (100.64.0.0/10)
-         * (shared address space to stack another layer of NAT) */
-        if ((ip4.uint8[0] == 100) && ((ip4.uint8[1] & 0xC0) == 0x40)) {
-            return true;
-        }
-    } else if (net_family_is_ipv6(ip.family)) {
+bool ip_is_lan(IP ip)
+{
+    if (ip_is_local(ip)) {
+        return true;
+    }
+
+    if (net_family_is_ipv4(ip.family)) {
+        return ip4_is_lan(ip.ip.v4);
+    }
 
+    if (net_family_is_ipv6(ip.family)) {
         /* autogenerated for each interface: FE80::* (up to FEBF::*)
            FF02::1 is - according to RFC 4291 - multicast all-nodes link-local */
         if (((ip.ip.v6.uint8[0] == 0xFF) && (ip.ip.v6.uint8[1] < 3) && (ip.ip.v6.uint8[15] == 1)) ||
@@ -346,10 +352,9 @@ bool ip_is_lan(IP ip)
 
         /* embedded IPv4-in-IPv6 */
         if (ipv6_ipv4_in_v6(ip.ip.v6)) {
-            IP ip4;
-            ip4.family = net_family_ipv4;
-            ip4.ip.v4.uint32 = ip.ip.v6.uint32[3];
-            return ip_is_lan(ip4);
+            IP4 ip4;
+            ip4.uint32 = ip.ip.v6.uint32[3];
+            return ip4_is_lan(ip4);
         }
     }