feat: add handling for unspecified IPs in connect function

Added a utility function to set loopback addresses for unspecified IPv4 and IPv6 addresses during socket connection attempts.
This ensures proper handling of "0.0.0.0" and "::" addresses.

src/net/netsyscall.c

@@ -446,7 +446,7 @@ static sysreturn sock_read_bh_internal(netsock s, struct msghdr *msg, int flags,
               s->sock.fd, ctx, iov, length, flags, bqflags, err);
     assert(s->sock.type == SOCK_STREAM || s->sock.type == SOCK_DGRAM);
 
-    if ((s->sock.type == SOCK_STREAM && s->info.tcp.state != TCP_SOCK_OPEN) || 
+    if ((s->sock.type == SOCK_STREAM && s->info.tcp.state != TCP_SOCK_OPEN) ||
             (s->sock.type == SOCK_DGRAM && s->info.udp.state == UDP_SOCK_SHUTDOWN)) {
         rv = 0;
         goto out_unlock;
@@ -1247,7 +1247,7 @@ static sysreturn netsock_shutdown(struct sock *sock, int how)
         rv = -ENOTCONN;
         goto out;
     }
-    
+
     rv = 0;
   out:
     /* Wake up any blockers waiting on the socket */
@@ -1684,6 +1684,19 @@ static inline sysreturn connect_tcp(netsock s, const ip_addr_t* address,
     return rv;
 }
 
+static inline void set_loopback_if_any(ip_addr_t *ipaddr)
+{
+    if (ipaddr->type == IPADDR_TYPE_V4) {
+        // Check if the IPv4 address is "0.0.0.0"
+        if (ip4_addr_isany(ip_2_ip4(ipaddr)))
+            ip4_addr_set_loopback(ip_2_ip4(ipaddr)); // "127.0.0.1"
+    } else if (ipaddr->type == IPADDR_TYPE_V6) {
+        // Check if the IPv6 address is "::"
+        if (ip6_addr_isany(ip_2_ip6(ipaddr)))
+            ip6_addr_set_loopback(ip_2_ip6(ipaddr)); // "::1"
+    }
+}
+
 static sysreturn netsock_connect(struct sock *sock, struct sockaddr *addr,
         socklen_t addrlen)
 {
@@ -1710,9 +1723,11 @@ static sysreturn netsock_connect(struct sock *sock, struct sockaddr *addr,
             msg_warn("attempt to connect on listening socket fd = %d; ignored\n", sock->fd);
             ret = -EINVAL;
         } else {
+            set_loopback_if_any(&ipaddr);
             ret = connect_tcp(s, &ipaddr, port);
         }
     } else if (s->sock.type == SOCK_DGRAM) {
+        set_loopback_if_any(&ipaddr);
         /* Set remote endpoint */
         ret = lwip_to_errno(udp_connect(s->info.udp.lw, &ipaddr, port));
     } else {