Network socket options: add support for IPPROTO_IP/IP_MTU_DISCOVER

This socket option controls the setting of the DF (don't fragment) flag in output IPv4 packets. Depends on nanovms/lwip#14.
nanovms · Oct 19, 2024 · 7f80293 · 7f80293
1 parent 4c77f77
commit 7f80293
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diff --git a/src/net/netsyscall.c b/src/net/netsyscall.c
@@ -412,6 +412,7 @@ static inline s64 lwip_to_errno(s8 err)
     case ERR_RST: return -ECONNRESET;
     case ERR_CLSD: return -ENOTCONN;
     case ERR_ARG: return -EIO;
+    case ERR_MSGSIZE: return -EMSGSIZE;
     }
     return -EINVAL;		/* XXX unknown - check return value */
 }
@@ -2386,6 +2387,24 @@ static sysreturn netsock_setsockopt(struct sock *sock, int level,
     int int_optval;
     sysreturn rv;
     switch (level) {
+    case IPPROTO_IP:
+        switch (optname) {
+        case IP_MTU_DISCOVER:
+            rv = sockopt_copy_from_user(optval, optlen, &int_optval, sizeof(int));
+            if (rv)
+                goto out;
+            if (s->sock.type == SOCK_STREAM) {
+                struct tcp_pcb *tcp_lw = netsock_tcp_get(s);
+                tcp_lw->pmtudisc = int_optval;
+                netsock_tcp_put(tcp_lw);
+            } else {
+                s->info.udp.lw->pmtudisc = int_optval;
+            }
+            break;
+        default:
+            goto unimplemented;
+        }
+        break;
     case IPPROTO_IPV6:
         switch (optname) {
         case IPV6_V6ONLY:
@@ -2696,6 +2715,21 @@ static sysreturn netsock_getsockopt(struct sock *sock, int level,
             goto unimplemented;
         }
         break;
+    case IPPROTO_IP:
+        switch (optname) {
+        case IP_MTU_DISCOVER:
+            if (s->sock.type == SOCK_STREAM) {
+                struct tcp_pcb *tcp_lw = netsock_tcp_get(s);
+                ret_optval.val = tcp_lw->pmtudisc;
+                netsock_tcp_put(tcp_lw);
+            } else {
+                ret_optval.val = s->info.udp.lw->pmtudisc;
+            }
+            break;
+        default:
+            goto unimplemented;
+        }
+        break;
     case IPPROTO_IPV6:
         switch (optname) {
         case IPV6_V6ONLY:

diff --git a/src/unix/system_structs.h b/src/unix/system_structs.h
@@ -863,6 +863,7 @@ struct io_uring_params {
 #define IP_TOS              1
 #define IP_TTL              2
 #define IP_OPTIONS          4
+#define IP_MTU_DISCOVER     10
 #define IP_MINTTL           21
 #define IP_MULTICAST_IF     32
 #define IP_MULTICAST_TTL    33