sockets: format every kernel address from its sockaddr, so a link-local address keeps its zone

packages/bun-types/bun.d.ts

@@ -5193,6 +5193,14 @@ declare module "bun" {
   interface SocketAddress {
     /**
      * The IP address of the client.
+     *
+     * A link-local IPv6 address (`fe80::/10`) has its zone: the name of the
+     * interface, or the index of the interface on Windows. `Bun.connect()`,
+     * `Bun.udpSocket()`, `node:net` and `node:dgram` take the address with
+     * its zone. A URL cannot hold a zone, so `fetch()` and `WebSocket` do
+     * not.
+     *
+     * @example "192.168.1.100" | "2001:db8::1" | "fe80::1%eth0"
      */
     address: string;
 
@@ -7310,7 +7318,10 @@ declare module "bun" {
 
     /**
      * Remote IP address connected to the socket
-     * @example "192.168.1.100" | "2001:db8::1"
+     *
+     * A link-local IPv6 address (`fe80::/10`) has its zone: the name of the
+     * interface, or the index of the interface on Windows.
+     * @example "192.168.1.100" | "2001:db8::1" | "fe80::1%eth0"
      */
     readonly remoteAddress: string;
 
@@ -7328,7 +7339,10 @@ declare module "bun" {
 
     /**
      * Local IP address connected to the socket
-     * @example "192.168.1.100" | "2001:db8::1"
+     *
+     * A link-local IPv6 address (`fe80::/10`) has its zone: the name of the
+     * interface, or the index of the interface on Windows.
+     * @example "192.168.1.100" | "2001:db8::1" | "fe80::1%eth0"
      */
     readonly localAddress: string;
 

packages/bun-types/serve.d.ts

@@ -265,6 +265,10 @@ declare module "bun" {
     /**
      * The IP address of the client.
      *
+     * A link-local IPv6 address (`fe80::/10`) has its zone: the name of the
+     * interface, or the index of the interface on Windows. For example
+     * `"fe80::1%eth0"`.
+     *
      * @example
      * ```ts
      * console.log(socket.remoteAddress); // "127.0.0.1"

packages/bun-usockets/src/bsd.c

@@ -956,6 +956,16 @@ int bsd_remote_addr(LIBUS_SOCKET_DESCRIPTOR fd, struct bsd_addr_t *addr) {
     return 0;
 }
 
+int bsd_local_sockaddr(LIBUS_SOCKET_DESCRIPTOR fd, struct sockaddr_storage *out) {
+    socklen_t len = sizeof(*out);
+    return getsockname(fd, (struct sockaddr *) out, &len) == 0 && (out->ss_family == AF_INET || out->ss_family == AF_INET6);
+}
+
+int bsd_remote_sockaddr(LIBUS_SOCKET_DESCRIPTOR fd, struct sockaddr_storage *out) {
+    socklen_t len = sizeof(*out);
+    return getpeername(fd, (struct sockaddr *) out, &len) == 0 && (out->ss_family == AF_INET || out->ss_family == AF_INET6);
+}
+
 char *bsd_addr_get_ip(struct bsd_addr_t *addr) {
     return addr->ip;
 }

packages/bun-usockets/src/internal/networking/bsd.h

@@ -212,6 +212,10 @@ void internal_finalize_bsd_addr(struct bsd_addr_t *addr);
 int bsd_local_addr(LIBUS_SOCKET_DESCRIPTOR fd, struct bsd_addr_t *addr);
 int bsd_remote_addr(LIBUS_SOCKET_DESCRIPTOR fd, struct bsd_addr_t *addr);
 
+/* getsockname() / getpeername() into `out`. Returns 1 for an AF_INET or AF_INET6 address, 0 otherwise. */
+int bsd_local_sockaddr(LIBUS_SOCKET_DESCRIPTOR fd, struct sockaddr_storage *out);
+int bsd_remote_sockaddr(LIBUS_SOCKET_DESCRIPTOR fd, struct sockaddr_storage *out);
+
 char *bsd_addr_get_ip(struct bsd_addr_t *addr);
 int bsd_addr_get_ip_length(struct bsd_addr_t *addr);
 

packages/bun-usockets/src/libusockets.h

@@ -186,6 +186,9 @@ struct us_udp_packet_buffer_t;
 struct ssl_ctx_st;
 struct ssl_st;
 
+/* <sys/socket.h> / <winsock2.h>. The address getters fill one whole: a link-local address needs its sin6_scope_id. */
+struct sockaddr_storage;
+
 /* Public interface for UDP sockets */
 
 /* Peeks data and length of UDP payload */
@@ -199,6 +202,10 @@ int us_udp_packet_buffer_truncated(struct us_udp_packet_buffer_t *buf, int index
 /* Get the bound port in host byte order */
 int us_udp_socket_bound_port(struct us_udp_socket_t *s);
 
+/* getsockname() / getpeername() into `out`. Returns 1 for an AF_INET or AF_INET6 address, 0 otherwise. */
+int us_udp_socket_local_sockaddr(struct us_udp_socket_t *s, struct sockaddr_storage *out);
+int us_udp_socket_remote_sockaddr(struct us_udp_socket_t *s, struct sockaddr_storage *out);
+
 /* Peeks peer addr (sockaddr) of received packet */
 char *us_udp_packet_buffer_peer(struct us_udp_packet_buffer_t *buf, int index);
 
@@ -725,8 +732,9 @@ struct us_socket_t *us_socket_close_lingering(us_socket_r s) nonnull_fn_decl;
 
 int us_socket_local_port(us_socket_r s) nonnull_fn_decl;
 int us_socket_remote_port(us_socket_r s) nonnull_fn_decl;
-void us_socket_remote_address(us_socket_r s, char *nonnull_arg buf, int *nonnull_arg length) nonnull_fn_decl;
-void us_socket_local_address(us_socket_r s, char *nonnull_arg buf, int *nonnull_arg length) nonnull_fn_decl;
+/* getsockname() / getpeername() into `out`. Returns 0 for a unix socket, a named pipe and a closed socket. */
+int us_socket_local_sockaddr(us_socket_r s, struct sockaddr_storage *nonnull_arg out) nonnull_fn_decl;
+int us_socket_remote_sockaddr(us_socket_r s, struct sockaddr_storage *nonnull_arg out) nonnull_fn_decl;
 
 int us_socket_ipc_write_fd(us_socket_r s, const char *data, int length, int fd) nonnull_fn_decl;
 /* Dispatches on_writable once the socket is writable, as if a us_socket_write() had come up short.
@@ -748,7 +756,6 @@ struct us_socket_t *us_socket_from_fd(us_socket_group_r group, unsigned char kin
     __attribute__((nonnull(1)));  /* ssl_ctx nullable */
 /* The bundled Mozilla root certificates, DER-encoded, in static memory. Returns the count. */
 size_t us_bundled_root_certs_der(const uint8_t *const **out_certs, const size_t **out_lens);
-unsigned int us_get_remote_address_info(char *buf, us_socket_r s, int *port);
 int us_socket_get_error(us_socket_r s);
 /* A writable event's write made zero progress: does that prove the peer is
  * gone? On epoll/kqueue a writable event implies real send-buffer space, so

packages/bun-usockets/src/quic.c

@@ -1274,15 +1274,9 @@ int us_quic_listen_socket_port(us_quic_udp_t *ls) {
         : ((struct sockaddr_in *) &ls->local)->sin_port);
 }
 
-int us_quic_listen_socket_local_address(us_quic_udp_t *ls, char *buf, int len) {
-    if (ls->local.ss_family == AF_INET6) {
-        if (len < 16) return 0;
-        memcpy(buf, &((struct sockaddr_in6 *) &ls->local)->sin6_addr, 16);
-        return 16;
-    }
-    if (len < 4) return 0;
-    memcpy(buf, &((struct sockaddr_in *) &ls->local)->sin_addr, 4);
-    return 4;
+int us_quic_listen_socket_local_sockaddr(us_quic_udp_t *ls, struct sockaddr_storage *out) {
+    *out = ls->local;
+    return out->ss_family == AF_INET || out->ss_family == AF_INET6;
 }
 
 #define DEF_CB(name, sig) \
@@ -1469,23 +1463,27 @@ int us_quic_stream_headers_too_large(us_quic_stream_t *s) {
 
 void *us_quic_socket_ext(us_quic_socket_t *s) { return s + 1; }
 
-void us_quic_socket_remote_address(us_quic_socket_t *s, char *buf, int *len, int *port, int *is_ipv6) {
+int us_quic_socket_remote_sockaddr(us_quic_socket_t *s, struct sockaddr_storage *out) {
     const struct sockaddr *local, *peer;
-    *len = 0; *port = 0; *is_ipv6 = 0;
-    if (lsquic_conn_get_sockaddr(s->conn, &local, &peer) != 0) return;
+    if (lsquic_conn_get_sockaddr(s->conn, &local, &peer) != 0) return 0;
     if (peer->sa_family == AF_INET6) {
         const struct sockaddr_in6 *a = (const struct sockaddr_in6 *) peer;
-        *port = ntohs(a->sin6_port);
         if (IN6_IS_ADDR_V4MAPPED(&a->sin6_addr)) {
-            *len = 4; memcpy(buf, (const char *) &a->sin6_addr + 12, 4);
+            /* An IPv4 peer of a dual-stack socket: ::ffff:a.b.c.d is reported as a.b.c.d. */
+            struct sockaddr_in v4;
+            memset(&v4, 0, sizeof(v4));
+            v4.sin_family = AF_INET;
+            v4.sin_port = a->sin6_port;
+            memcpy(&v4.sin_addr, (const char *) &a->sin6_addr + 12, 4);
+            memcpy(out, &v4, sizeof(v4));
         } else {
-            *is_ipv6 = 1; *len = 16; memcpy(buf, &a->sin6_addr, 16);
+            memcpy(out, a, sizeof(*a));
         }
-    } else {
-        const struct sockaddr_in *a = (const struct sockaddr_in *) peer;
-        *port = ntohs(a->sin_port);
-        *len = 4; memcpy(buf, &a->sin_addr, 4);
+        return 1;
     }
+    if (peer->sa_family != AF_INET) return 0;
+    memcpy(out, peer, sizeof(struct sockaddr_in));
+    return 1;
 }
 
 void us_quic_socket_close(us_quic_socket_t *s) { if (s->conn) lsquic_conn_close(s->conn); }

packages/bun-usockets/src/quic.h

@@ -122,7 +122,8 @@ us_quic_udp_t *us_quic_socket_context_listen(
 
 void us_quic_listen_socket_close(us_quic_udp_t *ls);
 int us_quic_listen_socket_port(us_quic_udp_t *ls);
-int us_quic_listen_socket_local_address(us_quic_udp_t *ls, char *buf, int len);
+/* The address that the listener is bound to, whole. Returns 1 for an AF_INET or AF_INET6 address, 0 otherwise. */
+int us_quic_listen_socket_local_sockaddr(us_quic_udp_t *ls, struct sockaddr_storage *out);
 
 /* Client engine: one shared lsquic engine for all outbound connections on
  * `loop`. Per-connection cert verification is decided at connect time. */
@@ -247,7 +248,8 @@ int us_quic_stream_headers_too_large(us_quic_stream_t *s);
 
 /* Connection accessors */
 void *us_quic_socket_ext(us_quic_socket_t *s);
-void us_quic_socket_remote_address(us_quic_socket_t *s, char *buf, int *len, int *port, int *is_ipv6);
+/* The peer of the connection, whole. An IPv4 peer of a dual-stack socket is AF_INET. Returns 1, or 0 with no peer. */
+int us_quic_socket_remote_sockaddr(us_quic_socket_t *s, struct sockaddr_storage *out);
 void us_quic_socket_close(us_quic_socket_t *s);
 
 #ifdef __cplusplus

packages/bun-usockets/src/socket.c

@@ -53,24 +53,15 @@ void us_connecting_socket_shutdown_read(struct us_connecting_socket_t *c) {
     c->shutdown_read = 1;
 }
 
-void us_socket_remote_address(struct us_socket_t *s, char *buf, int *length) {
-    struct bsd_addr_t addr;
-    if (bsd_remote_addr(us_poll_fd(&s->p), &addr) || *length < bsd_addr_get_ip_length(&addr)) {
-        *length = 0;
-    } else {
-        *length = bsd_addr_get_ip_length(&addr);
-        memcpy(buf, bsd_addr_get_ip(&addr), *length);
-    }
+/* 0 for a closed socket: the kernel can give its descriptor number to another connection. */
+int us_socket_local_sockaddr(struct us_socket_t *s, struct sockaddr_storage *out) {
+    if (us_socket_is_closed(s)) return 0;
+    return bsd_local_sockaddr(us_poll_fd(&s->p), out);
 }
 
-void us_socket_local_address(struct us_socket_t *s, char *buf, int *length) {
-    struct bsd_addr_t addr;
-    if (bsd_local_addr(us_poll_fd(&s->p), &addr) || *length < bsd_addr_get_ip_length(&addr)) {
-        *length = 0;
-    } else {
-        *length = bsd_addr_get_ip_length(&addr);
-        memcpy(buf, bsd_addr_get_ip(&addr), *length);
-    }
+int us_socket_remote_sockaddr(struct us_socket_t *s, struct sockaddr_storage *out) {
+    if (us_socket_is_closed(s)) return 0;
+    return bsd_remote_sockaddr(us_poll_fd(&s->p), out);
 }
 
 __attribute__((always_inline)) struct us_socket_group_t *us_socket_group(struct us_socket_t *s) {
@@ -802,28 +793,6 @@ int us_connecting_socket_get_dns_error(struct us_connecting_socket_t *c) {
     return c->error_is_dns ? c->error : 0;
 }
 
-unsigned int us_get_remote_address_info(char *buf, struct us_socket_t *s, int *port)
-{
-    // This function is manual inlining + modification of
-    //      us_socket_remote_address
-    //      AsyncSocket::getRemoteAddress
-    // To get { ip, port, is_ipv6 } for Bun.serve().requestIP()
-    struct bsd_addr_t addr;
-    if (bsd_remote_addr(us_poll_fd(&s->p), &addr)) {
-        return 0;
-    }
-
-    int length = bsd_addr_get_ip_length(&addr);
-    if (!length) {
-        return 0;
-    }
-
-    memcpy(buf, bsd_addr_get_ip(&addr), length);
-    *port = bsd_addr_get_port(&addr);
-
-    return length;
-}
-
 void us_socket_ref(struct us_socket_t *s) {
 #ifdef LIBUS_USE_LIBUV
     uv_ref((uv_handle_t *) s->p.uv_p);

packages/bun-usockets/src/udp.c

@@ -84,24 +84,12 @@ int us_udp_socket_bound_port(struct us_udp_socket_t *s) {
     return s->port;
 }
 
-void us_udp_socket_bound_ip(struct us_udp_socket_t *s, char *buf, int *length) {
-  struct bsd_addr_t addr;
-  if (bsd_local_addr(us_poll_fd((struct us_poll_t *)s), &addr) || *length < bsd_addr_get_ip_length(&addr)) {
-    *length = 0;
-  } else {
-    *length = bsd_addr_get_ip_length(&addr);
-    memcpy(buf, bsd_addr_get_ip(&addr), *length);
-  }
+int us_udp_socket_local_sockaddr(struct us_udp_socket_t *s, struct sockaddr_storage *out) {
+    return bsd_local_sockaddr(us_poll_fd((struct us_poll_t *) s), out);
 }
 
-void us_udp_socket_remote_ip(struct us_udp_socket_t *s, char *buf, int *length) {
-  struct bsd_addr_t addr;
-  if (bsd_remote_addr(us_poll_fd((struct us_poll_t *)s), &addr) || *length < bsd_addr_get_ip_length(&addr)) {
-    *length = 0;
-  } else {
-    *length = bsd_addr_get_ip_length(&addr);
-    memcpy(buf, bsd_addr_get_ip(&addr), *length);
-  }
+int us_udp_socket_remote_sockaddr(struct us_udp_socket_t *s, struct sockaddr_storage *out) {
+    return bsd_remote_sockaddr(us_poll_fd((struct us_poll_t *) s), out);
 }
 
 __attribute__((always_inline)) void *us_udp_socket_user(struct us_udp_socket_t *udp) {

packages/bun-uws/src/AsyncSocket.h

@@ -213,14 +213,6 @@ struct AsyncSocket {
         return true;
     }
 
-    /* Returns the remote IP address or empty string on failure */
-    std::string_view getRemoteAddress() {
-        static thread_local char buf[16];
-        int ipLength = 16;
-        us_socket_remote_address((us_socket_t *) this, buf, &ipLength);
-        return std::string_view(buf, (unsigned int) ipLength);
-    }
-
     /**
     * Flushes the socket buffer by writing as much data as possible to the underlying socket.
     *

packages/bun-uws/src/HttpResponse.h

@@ -692,7 +692,6 @@ struct HttpResponse : public AsyncSocket<SSL> {
     using Super::close;
 
     /* See AsyncSocket */
-    using Super::getRemoteAddress;
     using Super::getNativeHandle;
 
     /* Stops reading for a READ_PAUSE_* reason. The idle timeout keeps running, because a blocked response write has nothing else to end it. */

packages/bun-uws/src/WebSocket.h

@@ -60,7 +60,6 @@ struct WebSocket : AsyncSocket<SSL> {
 
     /* See AsyncSocket */
     using Super::getBufferedAmount;
-    using Super::getRemoteAddress;
     using Super::getNativeHandle;
 
     /* WebSocket close cannot be an alias to AsyncSocket::close since