fix gretap

1 files changed, 29 insertions, 15 deletions

diff --git a/gre.c b/gre.c
index c7bc46e..7ec4acd 100644
--- a/gre.c
+++ b/gre.c
@@ -46,7 +46,7 @@ static size_t remote_len;
 static short type = IFF_TUN;
 static uint8_t mac[6];
 
-uint8_t buf[4096];
+uint8_t buf[65536];
 
 static void gre_cb(void);
 static int gre_ipv4(uint8_t **buf, int *n);
@@ -187,7 +187,7 @@ static void gre_cb(void)
     int n;
     struct sockaddr_storage src;
     socklen_t src_len = sizeof(src);
-    uint8_t offset = type == IFF_TAP ? 6 + 6 + 2 : 0;
+    uint8_t offset = 0; //type == IFF_TAP ? 6 + 6 + 2 : 0;
 
     memset(&src, 0, src_len);
     n = recvfrom(sock, buf + offset, sizeof(buf)-offset, 0, (struct sockaddr*)&src, &src_len);
@@ -202,13 +202,16 @@ static void gre_cb(void)
     switch (remote.ss_family) {
         case AF_INET: res = gre_ipv4(&frame, &n); break;
         case AF_INET6: res = gre_ipv6(&frame, &n, (const struct sockaddr_in6*)&src); break;
-        default: return;
+        default: printf("Unknown family\n"); return;
     }
 
     if (res < 0)
+    {
+        printf("Failed GRE decode");
         return;
+    }
 
-    if ( type == IFF_TAP )
+    if ( 0 ) //type == IFF_TAP )
     {
         /* Set tuntap header */
         memset(frame - offset, 0, 2);
@@ -241,6 +244,7 @@ static int gre_ipv4(uint8_t **bufp, int *np)
     const struct sockaddr_in *remote_in = (const struct sockaddr_in *)&remote;
     if (*(uint32_t *)(buf + 12) != remote_in->sin_addr.s_addr)
     {
+        printf("Wrong IPv4 source\n");
         return -1;
     }
 
@@ -273,22 +277,33 @@ static int gre_ipv6(uint8_t **bufp, int *np, const struct sockaddr_in6 *src)
 
 static int gre_any(const uint8_t *buf, int n)
 {
+    //uint8_t offset = type == IFF_TAP ? 6 + 6 + 2 : 0;
+    uint8_t offset = 0;
+
     // parse GRE header
-    if (*(uint16_t *)(buf) != 0)
+    uint16_t *hdr = (uint16_t *)(buf+offset);
+    if (hdr[0] != 0)
     {
+        printf("Bad GRE header: %04x %04x\n", ntohs(hdr[0]), ntohs(hdr[1]));
         return -1;
     }
     uint16_t protocol = ntohs(*(uint16_t *)(buf + 2));
-    switch (protocol) {
-    case ETHERTYPE_IP:
-    case ETHERTYPE_IPV6:
-        break;
-    case ETHERTYPE_ARP:
-        if (type == IFF_TAP)
+    if (type == IFF_TUN)
+    {
+        switch (protocol) {
+        case ETHERTYPE_IP:
+        case ETHERTYPE_IPV6:
             break;
-        return -1;
-    default:
-        return -1;
+        default:
+            printf("Wrong proto: %04x\n", protocol);
+            return -1;
+        }
+    } else {
+        if (protocol != ETH_P_TEB)
+        {
+            printf("Wrong proto: %04x\n", protocol);
+            return -1;
+        }
     }
     return write(tun, buf, n);
 }
@@ -312,7 +327,6 @@ static int tun_cb(void)
 
     if (type == IFF_TAP)
     {
-        size_t ethsize = 6 + 6 + 2;
         frame = buf;
         *(uint16_t*)(frame + 2) = htons(ETH_P_TEB);
     } else {