Fix ICMP ping for IPv6: use IPPROTO_ICMPV6 and ICMPv6 packet format (#807)

* Initial plan

* Fix ICMP ping for IPv6: use IPPROTO_ICMPV6, ICMPv6 type codes, and handle no IP header in response

Co-authored-by: ithewei <26049660+ithewei@users.noreply.github.com>

* Fix ICMPv6 checksum, skip non-echo-reply packets, improve TTL display

Co-authored-by: ithewei <26049660+ithewei@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: ithewei <26049660+ithewei@users.noreply.github.com>

Author: Copilot

base/netinet.h

@@ -98,6 +98,10 @@ typedef struct tcphdr_s {
 #define ICMP_ADDRESS		17	/* Address Mask Request		*/
 #define ICMP_ADDRESSREPLY	18	/* Address Mask Reply		*/
 
+//----------------------icmpv6--------------------------------
+#define ICMP6_ECHO_REQUEST	128	/* ICMPv6 Echo Request		*/
+#define ICMP6_ECHO_REPLY	129	/* ICMPv6 Echo Reply		*/
+
 // sizeof(icmphdr_t) = 8
 typedef struct icmphdr_s {
     uint8_t     type;   // message type

protocol/icmp.c

@@ -35,7 +35,8 @@ int ping(const char* host, int cnt) {
     int ret = ResolveAddr(host, &peeraddr);
     if (ret != 0) return ret;
     sockaddr_ip(&peeraddr, ip, sizeof(ip));
-    int sockfd = socket(peeraddr.sa.sa_family, SOCK_RAW, IPPROTO_ICMP);
+    int is_ipv6 = (peeraddr.sa.sa_family == AF_INET6);
+    int sockfd = socket(peeraddr.sa.sa_family, SOCK_RAW, is_ipv6 ? IPPROTO_ICMPV6 : IPPROTO_ICMP);
     if (sockfd < 0) {
         perror("socket");
         if (errno == EPERM) {
@@ -57,7 +58,7 @@ int ping(const char* host, int cnt) {
         goto error;
     }
 
-    icmp_req->icmp_type = ICMP_ECHO;
+    icmp_req->icmp_type = is_ipv6 ? ICMP6_ECHO_REQUEST : ICMP_ECHO;
     icmp_req->icmp_code = 0;
     icmp_req->icmp_id = pid16;
     for (int i = 0; i < sendbytes - sizeof(icmphdr_t); ++i) {
@@ -68,7 +69,11 @@ int ping(const char* host, int cnt) {
         // NOTE: checksum
         icmp_req->icmp_seq = ++seq;
         icmp_req->icmp_cksum = 0;
-        icmp_req->icmp_cksum = checksum((uint8_t*)icmp_req, sendbytes);
+        // NOTE: ICMPv6 checksum includes a pseudo-header and is auto-computed
+        // by the kernel for IPPROTO_ICMPV6 raw sockets.
+        if (!is_ipv6) {
+            icmp_req->icmp_cksum = checksum((uint8_t*)icmp_req, sendbytes);
+        }
         start_hrtime = gethrtime_us();
         addrlen = sockaddr_len(&peeraddr);
         int nsend = sendto(sockfd, sendbuf, sendbytes, 0, &peeraddr.sa, addrlen);
@@ -77,8 +82,13 @@ int ping(const char* host, int cnt) {
             continue;
         }
         ++send_cnt;
-        addrlen = sizeof(peeraddr);
-        int nrecv = recvfrom(sockfd, recvbuf, sizeof(recvbuf), 0, &peeraddr.sa, &addrlen);
+        int nrecv;
+        do {
+            addrlen = sizeof(peeraddr);
+            nrecv = recvfrom(sockfd, recvbuf, sizeof(recvbuf), 0, &peeraddr.sa, &addrlen);
+            // For IPv6, raw sockets receive all ICMPv6 types (e.g. Neighbor
+            // Discovery).  Skip anything that is not an echo reply.
+        } while (is_ipv6 && nrecv >= (int)sizeof(icmphdr_t) && ((icmp_t*)recvbuf)->icmp_type != ICMP6_ECHO_REPLY);
         if (nrecv < 0) {
             perror("recvfrom");
             continue;
@@ -87,11 +97,11 @@ int ping(const char* host, int cnt) {
         end_hrtime = gethrtime_us();
         // check valid
         bool valid = false;
-        int iphdr_len = ipheader->ihl * 4;
+        int iphdr_len = is_ipv6 ? 0 : ipheader->ihl * 4;
         int icmp_len = nrecv - iphdr_len;
         if (icmp_len == sendbytes) {
-            icmp_res = (icmp_t*)(recvbuf + ipheader->ihl*4);
-            if (icmp_res->icmp_type == ICMP_ECHOREPLY &&
+            icmp_res = (icmp_t*)(recvbuf + iphdr_len);
+            if (icmp_res->icmp_type == (is_ipv6 ? ICMP6_ECHO_REPLY : ICMP_ECHOREPLY) &&
                 icmp_res->icmp_id == pid16 &&
                 icmp_res->icmp_seq == seq) {
                 valid = true;
@@ -105,7 +115,11 @@ int ping(const char* host, int cnt) {
         min_rtt = MIN(rtt, min_rtt);
         max_rtt = MAX(rtt, max_rtt);
         total_rtt += rtt;
-        printd("%d bytes from %s: icmp_seq=%u ttl=%u time=%.1f ms\n", icmp_len, ip, seq, ipheader->ttl, rtt);
+        if (is_ipv6) {
+            printd("%d bytes from %s: icmp_seq=%u hlim=? time=%.1f ms\n", icmp_len, ip, seq, rtt);
+        } else {
+            printd("%d bytes from %s: icmp_seq=%u ttl=%u time=%.1f ms\n", icmp_len, ip, seq, ipheader->ttl, rtt);
+        }
         fflush(stdout);
         ++ok_cnt;
         if (cnt > 0) hv_sleep(1); // sleep a while, then agian