net,tls: port Node.js net/tls compatibility tests and fix the gaps they surface

packages/bun-usockets/src/bsd.c

@@ -1261,6 +1261,10 @@ LIBUS_SOCKET_DESCRIPTOR bsd_create_listen_socket_unix(const char *path, size_t l
     struct sockaddr_un server_address;
     size_t addrlen = 0;
     if (bsd_create_unix_socket_address(path, len, &dirfd_workaround_for_unix_path_len, &server_address, &addrlen)) {
+        /* The path could not be expressed as a sockaddr_un (the basename
+         * exceeds sun_path even with the dirfd workaround); surface the errno
+         * so the caller can report something better than a codeless failure. */
+        if (error && errno) *error = errno;
         return LIBUS_SOCKET_ERROR;
     }
 
@@ -1599,12 +1603,31 @@ static int is_loopback(struct sockaddr_storage *sockaddr) {
 }
 #endif
 
-LIBUS_SOCKET_DESCRIPTOR bsd_create_connect_socket(struct sockaddr_storage *addr, int options) {
+LIBUS_SOCKET_DESCRIPTOR bsd_create_connect_socket(struct sockaddr_storage *addr, struct sockaddr_storage *local_addr, int options) {
     LIBUS_SOCKET_DESCRIPTOR fd = bsd_create_socket(addr->ss_family, SOCK_STREAM, 0, NULL);
     if (fd == LIBUS_SOCKET_ERROR) {
         return LIBUS_SOCKET_ERROR;
     }
 
+    /* Bind to the requested local address/port before connecting (the
+     * `localAddress`/`localPort` connect options). A failure here - typically
+     * EADDRINUSE or EADDRNOTAVAIL - fails the connect with that errno. */
+    if (local_addr) {
+        socklen_t local_len = local_addr->ss_family == AF_INET ? sizeof(struct sockaddr_in) : sizeof(struct sockaddr_in6);
+        if (bind(fd, (struct sockaddr *) local_addr, local_len)) {
+#ifdef _WIN32
+            int bind_err = WSAGetLastError();
+            bsd_close_socket(fd);
+            WSASetLastError(bind_err);
+#else
+            int bind_err = errno;
+            bsd_close_socket(fd);
+            errno = bind_err;
+#endif
+            return LIBUS_SOCKET_ERROR;
+        }
+    }
+
 #ifdef _WIN32
     win32_set_nonblocking(fd);
 

packages/bun-usockets/src/context.c

@@ -475,8 +475,8 @@ static inline void us_internal_init_connect_socket(struct us_socket_t *s,
 
 struct us_socket_t *us_socket_group_connect_resolved_dns(struct us_socket_group_t *group,
         unsigned char kind, struct ssl_ctx_st *ssl_ctx,
-        struct sockaddr_storage *addr, int options, int socket_ext_size) {
-    LIBUS_SOCKET_DESCRIPTOR connect_socket_fd = bsd_create_connect_socket(addr, options);
+        struct sockaddr_storage *addr, struct sockaddr_storage *local_addr, int options, int socket_ext_size) {
+    LIBUS_SOCKET_DESCRIPTOR connect_socket_fd = bsd_create_connect_socket(addr, local_addr, options);
     if (connect_socket_fd == LIBUS_SOCKET_ERROR) {
         return NULL;
     }
@@ -539,14 +539,22 @@ static bool try_parse_ip(const char *ip_str, int port, struct sockaddr_storage *
 }
 
 void *us_socket_group_connect(struct us_socket_group_t *group, unsigned char kind,
-        struct ssl_ctx_st *ssl_ctx, const char *host, int port, int options,
+        struct ssl_ctx_st *ssl_ctx, const char *host, int port,
+        const char *local_host, int local_port, int options,
         int socket_ext_size, int *has_dns_resolved) {
     struct us_loop_t *loop = group->loop;
 
+    /* The local address is always a literal IP (Node validates it as one). */
+    struct sockaddr_storage local_addr_storage;
+    struct sockaddr_storage *local_addr = NULL;
+    if (local_host && try_parse_ip(local_host, local_port, &local_addr_storage)) {
+        local_addr = &local_addr_storage;
+    }
+
     struct sockaddr_storage addr;
     if (try_parse_ip(host, port, &addr)) {
         *has_dns_resolved = 1;
-        return us_socket_group_connect_resolved_dns(group, kind, ssl_ctx, &addr, options, socket_ext_size);
+        return us_socket_group_connect_resolved_dns(group, kind, ssl_ctx, &addr, local_addr, options, socket_ext_size);
     }
 
     struct addrinfo_request *ai_req;
@@ -563,7 +571,7 @@ void *us_socket_group_connect(struct us_socket_group_t *group, unsigned char kin
             struct sockaddr_storage a;
             init_addr_with_port(&entries->info, port, &a);
             *has_dns_resolved = 1;
-            struct us_socket_t *s = us_socket_group_connect_resolved_dns(group, kind, ssl_ctx, &a, options, socket_ext_size);
+            struct us_socket_t *s = us_socket_group_connect_resolved_dns(group, kind, ssl_ctx, &a, local_addr, options, socket_ext_size);
             Bun__addrinfo_freeRequest(ai_req, s == NULL);
             return s;
         }
@@ -628,7 +636,8 @@ int start_connections(struct us_connecting_socket_t *c, int count) {
     for (; c->addrinfo_head != NULL && opened < count; c->addrinfo_head = c->addrinfo_head->ai_next) {
         struct sockaddr_storage addr;
         init_addr_with_port(c->addrinfo_head, c->port, &addr);
-        LIBUS_SOCKET_DESCRIPTOR connect_socket_fd = bsd_create_connect_socket(&addr, c->options);
+        /* The deferred-DNS path does not carry a local binding. */
+        LIBUS_SOCKET_DESCRIPTOR connect_socket_fd = bsd_create_connect_socket(&addr, NULL, c->options);
         if (connect_socket_fd == LIBUS_SOCKET_ERROR) {
             continue;
         }