feat(p5-socket): --address, -4/-6, --sockopts, server bind options

2026-09-09 13:41:28 +02:00
parent 90ccf297d7
commit 07d1dd84f7
15 changed files with 715 additions and 45 deletions
@@ -5,6 +5,8 @@
 #include <arpa/inet.h>
 #include <errno.h>
 #include <netdb.h>
+#include <netinet/in.h>
+#include <netinet/tcp.h>
 #include <openssl/ssl.h>
 #include <signal.h>
 #include <stdio.h>
@@ -28,47 +30,91 @@ static void sigchld_handler(int sig) {
  errno = saved_errno;
 }

-Server* server_create(int port) {
+/* Map a listen socket's address to its numeric port for logging, independent
+ * of whether it is an IPv4 or IPv6 sockaddr. */
+static unsigned short server_address_port(const struct sockaddr_storage* addr) {
+  if (addr->ss_family == AF_INET6)
+    return ntohs(((const struct sockaddr_in6*)addr)->sin6_port);
+  if (addr->ss_family == AF_INET)
+    return ntohs(((const struct sockaddr_in*)addr)->sin_port);
+  return 0;
+}
+
+Server* server_create_ex(int port, const ServerBindOptions* bind_opts) {
  Server* server = (Server*)malloc(sizeof(Server));
  if (server == NULL) {
    log_perror("Could not allocate space for Server");
    return NULL;
  }

-  int file_descriptor = socket(AF_INET, SOCK_STREAM, 0);
-  if (file_descriptor < 0) {
-    log_perror("Could not create Socket!");
-    free(server);
-    return NULL;
-  }
-  server->file_descriptor = file_descriptor;
-  int opt = 1;
-  if (setsockopt(server->file_descriptor, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt))) {
-    log_perror("Error setting a socket option!");
-    close(server->file_descriptor);
+  /* Effective address family.  preserve the historical default (IPv4 wildcard)
+   * when neither --address nor -4/-6 were given. */
+  int family = (bind_opts && bind_opts->family != AF_UNSPEC) ? bind_opts->family : AF_INET;
+  const char* bind_address = bind_opts ? bind_opts->bind_address : NULL;
+
+  struct addrinfo hints;
+  memset(&hints, 0, sizeof(hints));
+  hints.ai_family = family;
+  hints.ai_socktype = SOCK_STREAM;
+  hints.ai_protocol = IPPROTO_TCP;
+  hints.ai_flags = AI_PASSIVE;
+
+  char port_str[16];
+  snprintf(port_str, sizeof(port_str), "%d", port);
+
+  struct addrinfo* result = NULL;
+  int err = getaddrinfo(bind_address, port_str, &hints, &result);
+  if (err != 0 || result == NULL) {
+    char* escaped = bind_address ? output_escape(bind_address, false) : NULL;
+    fprintf(stderr, "Could not resolve bind address %s (%s)\n",
+            escaped ? escaped : "(wildcard)", gai_strerror(err));
+    free(escaped);
    free(server);
    return NULL;
  }

-  server->address.sin_family = AF_INET;
-  server->address.sin_addr.s_addr = INADDR_ANY;
-  server->address.sin_port = htons(port);
-  server->address_length = sizeof(server->address);
+  int file_descriptor = -1;
+  struct addrinfo* rp;
+  for (rp = result; rp != NULL; rp = rp->ai_next) {
+    file_descriptor = socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol);
+    if (file_descriptor < 0)
+      continue;
+    int opt = 1;
+    if (setsockopt(file_descriptor, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt)) != 0) {
+      log_perror("Error setting a socket option!");
+      close(file_descriptor);
+      file_descriptor = -1;
+      continue;
+    }
+    if (bind(file_descriptor, rp->ai_addr, (socklen_t)rp->ai_addrlen) == 0) {
+      memset(&server->address, 0, sizeof(server->address));
+      memcpy(&server->address, rp->ai_addr, rp->ai_addrlen);
+      server->address_length = rp->ai_addrlen;
+      break;
+    }
+    log_perror("Could not bind server address");
+    close(file_descriptor);
+    file_descriptor = -1;
+  }
+  freeaddrinfo(result);
+
+  if (file_descriptor < 0) {
+    free(server);
+    return NULL;
+  }
+
+  server->file_descriptor = file_descriptor;
  server->ssl_ctx = NULL;
  server->max_connections = 100;
  server->active_connections = 0;

-  if (bind(server->file_descriptor, (struct sockaddr*)&server->address, server->address_length) <
-      0) {
-    log_perror("Could not bind server");
-    close(server->file_descriptor);
-    free(server);
-    return NULL;
-  }
-
  return server;
 }

+Server* server_create(int port) {
+  return server_create_ex(port, NULL);
+}
+
 void server_delete(Server** server) {
  if (server == NULL || *server == NULL)
    return;
@@ -126,7 +172,8 @@ static void plain_child_fn(int fd, void* ctx) {
 }

 bool server_listen(Server* server, void (*handler)(int file_descriptor)) {
-  log_message(LOG_LEVEL_INFO, "Start Listening on Port: %d", ntohs(server->address.sin_port));
+  log_message(LOG_LEVEL_INFO, "Start Listening on Port: %d",
+              server_address_port(&server->address));
  struct plain_ctx ctx = {handler};
  accept_loop(server, plain_child_fn, &ctx, "Received Connection");
  return true;
@@ -134,7 +181,8 @@ bool server_listen(Server* server, void (*handler)(int file_descriptor)) {

 void server_accept_loop(Server* server, void (*child_fn)(int, void*), void* child_ctx,
                        const char* log_fmt) {
-  log_message(LOG_LEVEL_INFO, "Start TLS Listening on Port: %d", ntohs(server->address.sin_port));
+  log_message(LOG_LEVEL_INFO, "Start TLS Listening on Port: %d",
+              server_address_port(&server->address));
  accept_loop(server, child_fn, child_ctx, log_fmt);
 }

@@ -178,11 +226,100 @@ Client* client_create() {
  return client;
 }

-bool tcp_connect_socket(Client* client, char* host, int port) {
+int tcp_connect_family(bool ipv4, bool ipv6) {
+  if (ipv4)
+    return AF_INET;
+  if (ipv6)
+    return AF_INET6;
+  return AF_UNSPEC;
+}
+
+/* The socket-option apply layer maps an allowlist SockOptId to the concrete
+ * level/optname pair and applies it with the correct (int) value type.  The
+ * allowlist bounds what can ever reach this point, so the id-to-name mapping
+ * is total for every SOCKOPT_* value. */
+static int tcp_sockopt_level(SockOptId id) {
+  return id == SOCKOPT_TCP_NODELAY ? IPPROTO_TCP : SOL_SOCKET;
+}
+
+static int tcp_sockopt_name(SockOptId id) {
+  switch (id) {
+  case SOCKOPT_TCP_NODELAY:
+    return TCP_NODELAY;
+  case SOCKOPT_SO_KEEPALIVE:
+    return SO_KEEPALIVE;
+  case SOCKOPT_SO_RCVBUF:
+    return SO_RCVBUF;
+  case SOCKOPT_SO_SNDBUF:
+    return SO_SNDBUF;
+  case SOCKOPT_SO_REUSEADDR:
+    return SO_REUSEADDR;
+  default:
+    return -1;
+  }
+}
+
+static bool tcp_apply_sockopts(int fd, const SockOptEntry* sockopts, int sockopt_count) {
+  for (int i = 0; i < sockopt_count; i++) {
+    int name = tcp_sockopt_name(sockopts[i].id);
+    if (name < 0) { /* unreachable for a validated allowlist, but stay defensive */
+      log_message(LOG_LEVEL_ERROR, "Unsupported socket option requested");
+      return false;
+    }
+    int value = sockopts[i].value;
+    if (setsockopt(fd, tcp_sockopt_level(sockopts[i].id), name, &value, sizeof(value)) != 0) {
+      log_perror("Could not apply socket option");
+      return false;
+    }
+  }
+  return true;
+}
+
+/* Resolve an explicit --address source/bind address into a sockaddr once, so
+ * the per-candidate connect loop can bind() the outgoing socket to it.  The
+ * family follows the same -4/-6 hints as the destination resolution, so a
+ * forced family selects a matching local address; returns 0 on success. */
+static int resolve_bind_address(const char* addr, int family, struct sockaddr_storage* out,
+                                socklen_t* out_len, int* out_family) {
+  struct addrinfo hints;
+  memset(&hints, 0, sizeof(hints));
+  hints.ai_family = family; /* AF_UNSPEC when no -4/-6 */
+  hints.ai_socktype = SOCK_STREAM;
+  hints.ai_protocol = IPPROTO_TCP;
+
+  struct addrinfo* result = NULL;
+  int err = getaddrinfo(addr, NULL, &hints, &result);
+  if (err != 0 || result == NULL) {
+    char* escaped = output_escape(addr, false);
+    fprintf(stderr, "Could not resolve --address %s (%s)\n",
+            escaped ? escaped : "<allocation failed>", gai_strerror(err));
+    free(escaped);
+    return -1;
+  }
+  struct addrinfo* rp;
+  bool found = false;
+  for (rp = result; rp != NULL; rp = rp->ai_next) {
+    if (family != AF_UNSPEC && rp->ai_family != family)
+      continue;
+    memcpy(out, rp->ai_addr, rp->ai_addrlen);
+    *out_len = (socklen_t)rp->ai_addrlen;
+    *out_family = rp->ai_family;
+    found = true;
+    break;
+  }
+  freeaddrinfo(result);
+  return found ? 0 : -1;
+}
+
+bool tcp_connect_socket_ex(Client* client, const char* host, int port,
+                           const TcpConnectOptions* opts) {
  struct addrinfo hints;
  struct addrinfo* result;
  memset(&hints, 0, sizeof(hints));
-  hints.ai_family = AF_UNSPEC;
+  /* TcpConnectOptions.family already encodes -4/-6 (or AF_UNSPEC); feed it
+   * straight into the getaddrinfo hints so the destination resolution is
+   * (optionally) pinned to one address family. */
+  hints.ai_family = opts ? opts->family : AF_UNSPEC;
  hints.ai_socktype = SOCK_STREAM;
  hints.ai_protocol = IPPROTO_TCP;

@@ -198,6 +335,18 @@ bool tcp_connect_socket(Client* client, char* host, int port) {
    return false;
  }

+  /* Resolve the optional --address source address once up front. */
+  struct sockaddr_storage bind_addr;
+  socklen_t bind_addr_len = 0;
+  int bind_addr_family = 0;
+  if (opts && opts->bind_address) {
+    if (resolve_bind_address(opts->bind_address, hints.ai_family, &bind_addr, &bind_addr_len,
+                             &bind_addr_family) != 0) {
+      freeaddrinfo(result);
+      return false;
+    }
+  }
+
  struct addrinfo* rp;
  bool connected = false;
  for (rp = result; rp != NULL; rp = rp->ai_next) {
@@ -208,12 +357,33 @@ bool tcp_connect_socket(Client* client, char* host, int port) {
    if (client->file_descriptor < 0)
      continue;

+    if (opts && opts->sockopt_count > 0 &&
+        !tcp_apply_sockopts(client->file_descriptor, opts->sockopts, opts->sockopt_count)) {
+      close(client->file_descriptor);
+      client->file_descriptor = -1;
+      break;
+    }
+
    struct timeval ct;
    ct.tv_sec = g_contimeout_sec;
    ct.tv_usec = 0;
    setsockopt(client->file_descriptor, SOL_SOCKET, SO_RCVTIMEO, &ct, sizeof(ct));
    setsockopt(client->file_descriptor, SOL_SOCKET, SO_SNDTIMEO, &ct, sizeof(ct));

+    if (bind_addr_family != 0) {
+      if (rp->ai_family != bind_addr_family) {
+        close(client->file_descriptor);
+        client->file_descriptor = -1;
+        continue;
+      }
+      if (bind(client->file_descriptor, (struct sockaddr*)&bind_addr, bind_addr_len) != 0) {
+        log_perror("Could not bind outgoing socket to --address");
+        close(client->file_descriptor);
+        client->file_descriptor = -1;
+        break;
+      }
+    }
+
    memcpy(&client->address, rp->ai_addr, rp->ai_addrlen);
    client->address_length = rp->ai_addrlen;

@@ -233,8 +403,19 @@ bool tcp_connect_socket(Client* client, char* host, int port) {
  return true;
 }

+bool tcp_connect_socket(Client* client, char* host, int port) {
+  return tcp_connect_socket_ex(client, host, port, NULL);
+}
+
+bool client_connect_ex(Client* client, const char* host, int port, const TcpConnectOptions* opts) {
+  if (!tcp_connect_socket_ex(client, host, port, opts))
+    return false;
+  tcp_apply_socket_timeout(client->file_descriptor);
+  return true;
+}
+
 bool client_connect(Client* client, char* host, int port) {
-  if (!tcp_connect_socket(client, host, port))
+  if (!tcp_connect_socket_ex(client, host, port, NULL))
    return false;
  tcp_apply_socket_timeout(client->file_descriptor);
  return true;