X-Git-Url: https://tinc-vpn.org/git/browse?p=tinc;a=blobdiff_plain;f=src%2Froute.c;h=c1be6cb0ae4a607ce54f1bb1cf0519c1ff49a484;hp=a1254d80832491ee947e505c2c2050a9cd33e0fa;hb=6da826db2154321addb79c05b60a5e6f1a9dccf1;hpb=a588f6febeca13edd038d78e42efb8aa9f16a444

diff --git a/src/route.c b/src/route.c
index a1254d80..c1be6cb0 100644
--- a/src/route.c
+++ b/src/route.c
@@ -160,7 +160,7 @@ static void clamp_mss(const node_t *source, const node_t *via, vpn_packet_t *pac
 		/* Found it */
 		uint16_t oldmss = packet->data[start + 22 + i] << 8 | packet->data[start + 23 + i];
 		uint16_t newmss = mtu - start - 20;
-		uint16_t csum = packet->data[start + 16] << 8 | packet->data[start + 17];
+		uint32_t csum = packet->data[start + 16] << 8 | packet->data[start + 17];
 
 		if(oldmss <= newmss)
 			break;
@@ -171,11 +171,13 @@ static void clamp_mss(const node_t *source, const node_t *via, vpn_packet_t *pac
 		packet->data[start + 22 + i] = newmss >> 8;
 		packet->data[start + 23 + i] = newmss & 0xff;
 		csum ^= 0xffff;
-		csum -= oldmss;
+		csum += oldmss ^ 0xffff;
 		csum += newmss;
+		csum = (csum & 0xffff) + (csum >> 16);
+		csum += csum >> 16;
 		csum ^= 0xffff;
 		packet->data[start + 16] = csum >> 8;
-		packet->data[start + 17] = csum & 0xff;
+		packet->data[start + 17] = csum;
 		break;
 	}
 }
@@ -275,6 +277,27 @@ static void route_ipv4_unreachable(node_t *source, vpn_packet_t *packet, length_
 	ip_src = ip.ip_src;
 	ip_dst = ip.ip_dst;
 
+	/* Try to reply with an IP address assigned to the local machine */
+
+	if (type == ICMP_TIME_EXCEEDED && code == ICMP_EXC_TTL) {
+		int sockfd = socket(AF_INET, SOCK_DGRAM, 0);
+		if (sockfd != -1) {
+			struct sockaddr_in addr;
+			memset(&addr, 0, sizeof(addr));
+			addr.sin_family = AF_INET;
+			addr.sin_addr = ip.ip_src;
+			if (!connect(sockfd, (const struct sockaddr*) &addr, sizeof(addr))) {
+				memset(&addr, 0, sizeof(addr));
+				addr.sin_family = AF_INET;
+				socklen_t addrlen = sizeof(addr);
+				if (!getsockname(sockfd, (struct sockaddr*) &addr, &addrlen) && addrlen <= sizeof(addr)) {
+					ip_dst = addr.sin_addr;
+				}
+			}
+			close(sockfd);
+		}
+	}
+
 	oldlen = packet->len - ether_size;
 
 	if(type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
@@ -477,6 +500,27 @@ static void route_ipv6_unreachable(node_t *source, vpn_packet_t *packet, length_
 	pseudo.ip6_src = ip6.ip6_dst;
 	pseudo.ip6_dst = ip6.ip6_src;
 
+	/* Try to reply with an IP address assigned to the local machine */
+
+	if (type == ICMP6_TIME_EXCEEDED && code == ICMP6_TIME_EXCEED_TRANSIT) {
+		int sockfd = socket(AF_INET6, SOCK_DGRAM, 0);
+		if (sockfd != -1) {
+			struct sockaddr_in6 addr;
+			memset(&addr, 0, sizeof(addr));
+			addr.sin6_family = AF_INET6;
+			addr.sin6_addr = ip6.ip6_src;
+			if (!connect(sockfd, (const struct sockaddr*) &addr, sizeof(addr))) {
+				memset(&addr, 0, sizeof(addr));
+				addr.sin6_family = AF_INET6;
+				socklen_t addrlen = sizeof(addr);
+				if (!getsockname(sockfd, (struct sockaddr*) &addr, &addrlen) && addrlen <= sizeof(addr)) {
+					pseudo.ip6_src = addr.sin6_addr;
+				}
+			}
+			close(sockfd);
+		}
+	}
+
 	pseudo.length = packet->len - ether_size;
 
 	if(type == ICMP6_PACKET_TOO_BIG)