Adding upstream version 0.12.1+dfsg.upstream/0.12.1+dfsgupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 720 insertions, 0 deletions

diff --git a/examples/gtlssimpleclient.c b/examples/gtlssimpleclient.c
new file mode 100644
index 0000000..60c0121
--- /dev/null
+++ b/examples/gtlssimpleclient.c
@@ -0,0 +1,720 @@
+/*
+ * ngtcp2
+ *
+ * Copyright (c) 2021-2022 ngtcp2 contributors
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+ * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+#ifdef HAVE_CONFIG_H
+#  include <config.h>
+#endif /* HAVE_CONFIG_H */
+
+#include <time.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netdb.h>
+#include <arpa/inet.h>
+#include <string.h>
+#include <stdio.h>
+#include <errno.h>
+
+#include <ngtcp2/ngtcp2.h>
+#include <ngtcp2/ngtcp2_crypto.h>
+#include <ngtcp2/ngtcp2_crypto_gnutls.h>
+
+#include <gnutls/crypto.h>
+#include <gnutls/gnutls.h>
+
+#include <ev.h>
+
+#define REMOTE_HOST "127.0.0.1"
+#define REMOTE_PORT "4433"
+#define ALPN "hq-interop"
+#define MESSAGE "GET /\r\n"
+
+/*
+ * Example 1: Handshake with www.google.com
+ *
+ * #define REMOTE_HOST "www.google.com"
+ * #define REMOTE_PORT "443"
+ * #define ALPN "h3"
+ *
+ * and undefine MESSAGE macro.
+ */
+
+static uint64_t timestamp(void) {
+  struct timespec tp;
+
+  if (clock_gettime(CLOCK_MONOTONIC, &tp) != 0) {
+    fprintf(stderr, "clock_gettime: %s\n", strerror(errno));
+    exit(EXIT_FAILURE);
+  }
+
+  return (uint64_t)tp.tv_sec * NGTCP2_SECONDS + (uint64_t)tp.tv_nsec;
+}
+
+static int create_sock(struct sockaddr *addr, socklen_t *paddrlen,
+                       const char *host, const char *port) {
+  struct addrinfo hints = {0};
+  struct addrinfo *res, *rp;
+  int rv;
+  int fd = -1;
+
+  hints.ai_flags = AF_UNSPEC;
+  hints.ai_socktype = SOCK_DGRAM;
+
+  rv = getaddrinfo(host, port, &hints, &res);
+  if (rv != 0) {
+    fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv));
+    return -1;
+  }
+
+  for (rp = res; rp; rp = rp->ai_next) {
+    fd = socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol);
+    if (fd == -1) {
+      continue;
+    }
+
+    break;
+  }
+
+  if (fd == -1) {
+    goto end;
+  }
+
+  *paddrlen = rp->ai_addrlen;
+  memcpy(addr, rp->ai_addr, rp->ai_addrlen);
+
+end:
+  freeaddrinfo(res);
+
+  return fd;
+}
+
+static int connect_sock(struct sockaddr *local_addr, socklen_t *plocal_addrlen,
+                        int fd, const struct sockaddr *remote_addr,
+                        size_t remote_addrlen) {
+  socklen_t len;
+
+  if (connect(fd, remote_addr, (socklen_t)remote_addrlen) != 0) {
+    fprintf(stderr, "connect: %s\n", strerror(errno));
+    return -1;
+  }
+
+  len = *plocal_addrlen;
+
+  if (getsockname(fd, local_addr, &len) == -1) {
+    fprintf(stderr, "getsockname: %s\n", strerror(errno));
+    return -1;
+  }
+
+  *plocal_addrlen = len;
+
+  return 0;
+}
+
+struct client {
+  ngtcp2_crypto_conn_ref conn_ref;
+  int fd;
+  struct sockaddr_storage local_addr;
+  socklen_t local_addrlen;
+  gnutls_certificate_credentials_t cred;
+  gnutls_session_t session;
+  ngtcp2_conn *conn;
+
+  struct {
+    int64_t stream_id;
+    const uint8_t *data;
+    size_t datalen;
+    size_t nwrite;
+  } stream;
+
+  ngtcp2_connection_close_error last_error;
+
+  ev_io rev;
+  ev_timer timer;
+};
+
+static int hook_func(gnutls_session_t session, unsigned int htype,
+                     unsigned when, unsigned int incoming,
+                     const gnutls_datum_t *msg) {
+  (void)session;
+  (void)htype;
+  (void)when;
+  (void)incoming;
+  (void)msg;
+  /* we could save session data here */
+
+  return 0;
+}
+
+static int numeric_host_family(const char *hostname, int family) {
+  uint8_t dst[sizeof(struct in6_addr)];
+  return inet_pton(family, hostname, dst) == 1;
+}
+
+static int numeric_host(const char *hostname) {
+  return numeric_host_family(hostname, AF_INET) ||
+         numeric_host_family(hostname, AF_INET6);
+}
+
+static const char priority[] =
+    "NORMAL:-VERS-ALL:+VERS-TLS1.3:-CIPHER-ALL:+AES-128-GCM:+AES-256-GCM:"
+    "+CHACHA20-POLY1305:+AES-128-CCM:-GROUP-ALL:+GROUP-SECP256R1:+GROUP-X25519:"
+    "+GROUP-SECP384R1:"
+    "+GROUP-SECP521R1:%DISABLE_TLS13_COMPAT_MODE";
+
+static const gnutls_datum_t alpn = {(uint8_t *)ALPN, sizeof(ALPN) - 1};
+
+static int client_gnutls_init(struct client *c) {
+  int rv = gnutls_certificate_allocate_credentials(&c->cred);
+
+  if (rv == 0)
+    rv = gnutls_certificate_set_x509_system_trust(c->cred);
+  if (rv < 0) {
+    fprintf(stderr, "cred init failed: %d: %s\n", rv, gnutls_strerror(rv));
+    return -1;
+  }
+
+  rv = gnutls_init(&c->session, GNUTLS_CLIENT | GNUTLS_ENABLE_EARLY_DATA |
+                                    GNUTLS_NO_END_OF_EARLY_DATA);
+  if (rv != 0) {
+    fprintf(stderr, "gnutls_init: %s\n", gnutls_strerror(rv));
+    return -1;
+  }
+
+  if (ngtcp2_crypto_gnutls_configure_client_session(c->session) != 0) {
+    fprintf(stderr, "ngtcp2_crypto_gnutls_configure_client_session failed\n");
+    return -1;
+  }
+
+  rv = gnutls_priority_set_direct(c->session, priority, NULL);
+  if (rv != 0) {
+    fprintf(stderr, "gnutls_priority_set_direct: %s\n", gnutls_strerror(rv));
+    return -1;
+  }
+
+  gnutls_handshake_set_hook_function(c->session, GNUTLS_HANDSHAKE_ANY,
+                                     GNUTLS_HOOK_POST, hook_func);
+
+  gnutls_session_set_ptr(c->session, &c->conn_ref);
+
+  rv = gnutls_credentials_set(c->session, GNUTLS_CRD_CERTIFICATE, c->cred);
+
+  if (rv != 0) {
+    fprintf(stderr, "gnutls_credentials_set: %s\n", gnutls_strerror(rv));
+    return -1;
+  }
+
+  gnutls_alpn_set_protocols(c->session, &alpn, 1, GNUTLS_ALPN_MANDATORY);
+
+  if (!numeric_host(REMOTE_HOST)) {
+    gnutls_server_name_set(c->session, GNUTLS_NAME_DNS, REMOTE_HOST,
+                           strlen(REMOTE_HOST));
+  } else {
+    gnutls_server_name_set(c->session, GNUTLS_NAME_DNS, "localhost",
+                           strlen("localhost"));
+  }
+
+  return 0;
+}
+
+static void rand_cb(uint8_t *dest, size_t destlen,
+                    const ngtcp2_rand_ctx *rand_ctx) {
+  (void)rand_ctx;
+
+  (void)gnutls_rnd(GNUTLS_RND_RANDOM, dest, destlen);
+}
+
+static int get_new_connection_id_cb(ngtcp2_conn *conn, ngtcp2_cid *cid,
+                                    uint8_t *token, size_t cidlen,
+                                    void *user_data) {
+  (void)conn;
+  (void)user_data;
+
+  if (gnutls_rnd(GNUTLS_RND_RANDOM, cid->data, cidlen) != 0) {
+    return NGTCP2_ERR_CALLBACK_FAILURE;
+  }
+
+  cid->datalen = cidlen;
+
+  if (gnutls_rnd(GNUTLS_RND_RANDOM, token, NGTCP2_STATELESS_RESET_TOKENLEN) !=
+      0) {
+    return NGTCP2_ERR_CALLBACK_FAILURE;
+  }
+
+  return 0;
+}
+
+static int extend_max_local_streams_bidi(ngtcp2_conn *conn,
+                                         uint64_t max_streams,
+                                         void *user_data) {
+#ifdef MESSAGE
+  struct client *c = user_data;
+  int rv;
+  int64_t stream_id;
+  (void)max_streams;
+
+  if (c->stream.stream_id != -1) {
+    return 0;
+  }
+
+  rv = ngtcp2_conn_open_bidi_stream(conn, &stream_id, NULL);
+  if (rv != 0) {
+    return 0;
+  }
+
+  c->stream.stream_id = stream_id;
+  c->stream.data = (const uint8_t *)MESSAGE;
+  c->stream.datalen = sizeof(MESSAGE) - 1;
+
+  return 0;
+#else  /* !MESSAGE */
+  (void)conn;
+  (void)max_streams;
+  (void)user_data;
+
+  return 0;
+#endif /* !MESSAGE */
+}
+
+static void log_printf(void *user_data, const char *fmt, ...) {
+  va_list ap;
+  (void)user_data;
+
+  va_start(ap, fmt);
+  vfprintf(stderr, fmt, ap);
+  va_end(ap);
+
+  fprintf(stderr, "\n");
+}
+
+static int client_quic_init(struct client *c,
+                            const struct sockaddr *remote_addr,
+                            socklen_t remote_addrlen,
+                            const struct sockaddr *local_addr,
+                            socklen_t local_addrlen) {
+  ngtcp2_path path = {
+      {
+          (struct sockaddr *)local_addr,
+          local_addrlen,
+      },
+      {
+          (struct sockaddr *)remote_addr,
+          remote_addrlen,
+      },
+      NULL,
+  };
+  ngtcp2_callbacks callbacks = {
+      ngtcp2_crypto_client_initial_cb,
+      NULL, /* recv_client_initial */
+      ngtcp2_crypto_recv_crypto_data_cb,
+      NULL, /* handshake_completed */
+      NULL, /* recv_version_negotiation */
+      ngtcp2_crypto_encrypt_cb,
+      ngtcp2_crypto_decrypt_cb,
+      ngtcp2_crypto_hp_mask_cb,
+      NULL, /* recv_stream_data */
+      NULL, /* acked_stream_data_offset */
+      NULL, /* stream_open */
+      NULL, /* stream_close */
+      NULL, /* recv_stateless_reset */
+      ngtcp2_crypto_recv_retry_cb,
+      extend_max_local_streams_bidi,
+      NULL, /* extend_max_local_streams_uni */
+      rand_cb,
+      get_new_connection_id_cb,
+      NULL, /* remove_connection_id */
+      ngtcp2_crypto_update_key_cb,
+      NULL, /* path_validation */
+      NULL, /* select_preferred_address */
+      NULL, /* stream_reset */
+      NULL, /* extend_max_remote_streams_bidi */
+      NULL, /* extend_max_remote_streams_uni */
+      NULL, /* extend_max_stream_data */
+      NULL, /* dcid_status */
+      NULL, /* handshake_confirmed */
+      NULL, /* recv_new_token */
+      ngtcp2_crypto_delete_crypto_aead_ctx_cb,
+      ngtcp2_crypto_delete_crypto_cipher_ctx_cb,
+      NULL, /* recv_datagram */
+      NULL, /* ack_datagram */
+      NULL, /* lost_datagram */
+      ngtcp2_crypto_get_path_challenge_data_cb,
+      NULL, /* stream_stop_sending */
+      ngtcp2_crypto_version_negotiation_cb,
+      NULL, /* recv_rx_key */
+      NULL, /* recv_tx_key */
+      NULL, /* early_data_rejected */
+  };
+  ngtcp2_cid dcid, scid;
+  ngtcp2_settings settings;
+  ngtcp2_transport_params params;
+  int rv;
+
+  dcid.datalen = NGTCP2_MIN_INITIAL_DCIDLEN;
+  if (gnutls_rnd(GNUTLS_RND_RANDOM, dcid.data, dcid.datalen) != 0) {
+    fprintf(stderr, "gnutls_rnd failed\n");
+    return -1;
+  }
+
+  scid.datalen = 8;
+  if (gnutls_rnd(GNUTLS_RND_RANDOM, scid.data, scid.datalen) != 0) {
+    fprintf(stderr, "gnutls_rnd failed\n");
+    return -1;
+  }
+
+  ngtcp2_settings_default(&settings);
+
+  settings.initial_ts = timestamp();
+  settings.log_printf = log_printf;
+
+  ngtcp2_transport_params_default(&params);
+
+  params.initial_max_streams_uni = 3;
+  params.initial_max_stream_data_bidi_local = 128 * 1024;
+  params.initial_max_data = 1024 * 1024;
+
+  rv =
+      ngtcp2_conn_client_new(&c->conn, &dcid, &scid, &path, NGTCP2_PROTO_VER_V1,
+                             &callbacks, &settings, &params, NULL, c);
+  if (rv != 0) {
+    fprintf(stderr, "ngtcp2_conn_client_new: %s\n", ngtcp2_strerror(rv));
+    return -1;
+  }
+
+  ngtcp2_conn_set_tls_native_handle(c->conn, c->session);
+
+  return 0;
+}
+
+static int client_read(struct client *c) {
+  uint8_t buf[65536];
+  struct sockaddr_storage addr;
+  struct iovec iov = {buf, sizeof(buf)};
+  struct msghdr msg = {0};
+  ssize_t nread;
+  ngtcp2_path path;
+  ngtcp2_pkt_info pi = {0};
+  int rv;
+
+  msg.msg_name = &addr;
+  msg.msg_iov = &iov;
+  msg.msg_iovlen = 1;
+
+  for (;;) {
+    msg.msg_namelen = sizeof(addr);
+
+    nread = recvmsg(c->fd, &msg, MSG_DONTWAIT);
+
+    if (nread == -1) {
+      if (errno != EAGAIN && errno != EWOULDBLOCK) {
+        fprintf(stderr, "recvmsg: %s\n", strerror(errno));
+      }
+
+      break;
+    }
+
+    path.local.addrlen = c->local_addrlen;
+    path.local.addr = (struct sockaddr *)&c->local_addr;
+    path.remote.addrlen = msg.msg_namelen;
+    path.remote.addr = msg.msg_name;
+
+    rv = ngtcp2_conn_read_pkt(c->conn, &path, &pi, buf, (size_t)nread,
+                              timestamp());
+    if (rv != 0) {
+      fprintf(stderr, "ngtcp2_conn_read_pkt: %s\n", ngtcp2_strerror(rv));
+      if (!c->last_error.error_code) {
+        if (rv == NGTCP2_ERR_CRYPTO) {
+          ngtcp2_connection_close_error_set_transport_error_tls_alert(
+              &c->last_error, ngtcp2_conn_get_tls_alert(c->conn), NULL, 0);
+        } else {
+          ngtcp2_connection_close_error_set_transport_error_liberr(
+              &c->last_error, rv, NULL, 0);
+        }
+      }
+      return -1;
+    }
+  }
+
+  return 0;
+}
+
+static int client_send_packet(struct client *c, const uint8_t *data,
+                              size_t datalen) {
+  struct iovec iov = {(uint8_t *)data, datalen};
+  struct msghdr msg = {0};
+  ssize_t nwrite;
+
+  msg.msg_iov = &iov;
+  msg.msg_iovlen = 1;
+
+  do {
+    nwrite = sendmsg(c->fd, &msg, 0);
+  } while (nwrite == -1 && errno == EINTR);
+
+  if (nwrite == -1) {
+    fprintf(stderr, "sendmsg: %s\n", strerror(errno));
+
+    return -1;
+  }
+
+  return 0;
+}
+
+static size_t client_get_message(struct client *c, int64_t *pstream_id,
+                                 int *pfin, ngtcp2_vec *datav,
+                                 size_t datavcnt) {
+  if (datavcnt == 0) {
+    return 0;
+  }
+
+  if (c->stream.stream_id != -1 && c->stream.nwrite < c->stream.datalen) {
+    *pstream_id = c->stream.stream_id;
+    *pfin = 1;
+    datav->base = (uint8_t *)c->stream.data + c->stream.nwrite;
+    datav->len = c->stream.datalen - c->stream.nwrite;
+    return 1;
+  }
+
+  *pstream_id = -1;
+  *pfin = 0;
+  datav->base = NULL;
+  datav->len = 0;
+
+  return 0;
+}
+
+static int client_write_streams(struct client *c) {
+  ngtcp2_tstamp ts = timestamp();
+  ngtcp2_pkt_info pi;
+  ngtcp2_ssize nwrite;
+  uint8_t buf[1280];
+  ngtcp2_path_storage ps;
+  ngtcp2_vec datav;
+  size_t datavcnt;
+  int64_t stream_id;
+  ngtcp2_ssize wdatalen;
+  uint32_t flags;
+  int fin;
+
+  ngtcp2_path_storage_zero(&ps);
+
+  for (;;) {
+    datavcnt = client_get_message(c, &stream_id, &fin, &datav, 1);
+
+    flags = NGTCP2_WRITE_STREAM_FLAG_MORE;
+    if (fin) {
+      flags |= NGTCP2_WRITE_STREAM_FLAG_FIN;
+    }
+
+    nwrite = ngtcp2_conn_writev_stream(c->conn, &ps.path, &pi, buf, sizeof(buf),
+                                       &wdatalen, flags, stream_id, &datav,
+                                       datavcnt, ts);
+    if (nwrite < 0) {
+      switch (nwrite) {
+      case NGTCP2_ERR_WRITE_MORE:
+        c->stream.nwrite += (size_t)wdatalen;
+        continue;
+      default:
+        fprintf(stderr, "ngtcp2_conn_writev_stream: %s\n",
+                ngtcp2_strerror((int)nwrite));
+        ngtcp2_connection_close_error_set_transport_error_liberr(
+            &c->last_error, (int)nwrite, NULL, 0);
+        return -1;
+      }
+    }
+
+    if (nwrite == 0) {
+      return 0;
+    }
+
+    if (wdatalen > 0) {
+      c->stream.nwrite += (size_t)wdatalen;
+    }
+
+    if (client_send_packet(c, buf, (size_t)nwrite) != 0) {
+      break;
+    }
+  }
+
+  return 0;
+}
+
+static int client_write(struct client *c) {
+  ngtcp2_tstamp expiry, now;
+  ev_tstamp t;
+
+  if (client_write_streams(c) != 0) {
+    return -1;
+  }
+
+  expiry = ngtcp2_conn_get_expiry(c->conn);
+  now = timestamp();
+
+  t = expiry < now ? 1e-9 : (ev_tstamp)(expiry - now) / NGTCP2_SECONDS;
+
+  c->timer.repeat = t;
+  ev_timer_again(EV_DEFAULT, &c->timer);
+
+  return 0;
+}
+
+static int client_handle_expiry(struct client *c) {
+  int rv = ngtcp2_conn_handle_expiry(c->conn, timestamp());
+  if (rv != 0) {
+    fprintf(stderr, "ngtcp2_conn_handle_expiry: %s\n", ngtcp2_strerror(rv));
+    return -1;
+  }
+
+  return 0;
+}
+
+static void client_close(struct client *c) {
+  ngtcp2_ssize nwrite;
+  ngtcp2_pkt_info pi;
+  ngtcp2_path_storage ps;
+  uint8_t buf[1280];
+
+  if (ngtcp2_conn_is_in_closing_period(c->conn) ||
+      ngtcp2_conn_is_in_draining_period(c->conn)) {
+    goto fin;
+  }
+
+  ngtcp2_path_storage_zero(&ps);
+
+  nwrite = ngtcp2_conn_write_connection_close(
+      c->conn, &ps.path, &pi, buf, sizeof(buf), &c->last_error, timestamp());
+  if (nwrite < 0) {
+    fprintf(stderr, "ngtcp2_conn_write_connection_close: %s\n",
+            ngtcp2_strerror((int)nwrite));
+    goto fin;
+  }
+
+  client_send_packet(c, buf, (size_t)nwrite);
+
+fin:
+  ev_break(EV_DEFAULT, EVBREAK_ALL);
+}
+
+static void read_cb(struct ev_loop *loop, ev_io *w, int revents) {
+  struct client *c = w->data;
+  (void)loop;
+  (void)revents;
+
+  if (client_read(c) != 0) {
+    client_close(c);
+    return;
+  }
+
+  if (client_write(c) != 0) {
+    client_close(c);
+  }
+}
+
+static void timer_cb(struct ev_loop *loop, ev_timer *w, int revents) {
+  struct client *c = w->data;
+  (void)loop;
+  (void)revents;
+
+  if (client_handle_expiry(c) != 0) {
+    client_close(c);
+    return;
+  }
+
+  if (client_write(c) != 0) {
+    client_close(c);
+  }
+}
+
+static ngtcp2_conn *get_conn(ngtcp2_crypto_conn_ref *conn_ref) {
+  struct client *c = conn_ref->user_data;
+  return c->conn;
+}
+
+static int client_init(struct client *c) {
+  struct sockaddr_storage remote_addr, local_addr;
+  socklen_t remote_addrlen, local_addrlen = sizeof(local_addr);
+
+  memset(c, 0, sizeof(*c));
+
+  ngtcp2_connection_close_error_default(&c->last_error);
+
+  c->fd = create_sock((struct sockaddr *)&remote_addr, &remote_addrlen,
+                      REMOTE_HOST, REMOTE_PORT);
+  if (c->fd == -1) {
+    return -1;
+  }
+
+  if (connect_sock((struct sockaddr *)&local_addr, &local_addrlen, c->fd,
+                   (struct sockaddr *)&remote_addr, remote_addrlen) != 0) {
+    return -1;
+  }
+
+  memcpy(&c->local_addr, &local_addr, sizeof(c->local_addr));
+  c->local_addrlen = local_addrlen;
+
+  if (client_gnutls_init(c) != 0) {
+    return -1;
+  }
+
+  if (client_quic_init(c, (struct sockaddr *)&remote_addr, remote_addrlen,
+                       (struct sockaddr *)&local_addr, local_addrlen) != 0) {
+    return -1;
+  }
+
+  c->stream.stream_id = -1;
+
+  c->conn_ref.get_conn = get_conn;
+  c->conn_ref.user_data = c;
+
+  ev_io_init(&c->rev, read_cb, c->fd, EV_READ);
+  c->rev.data = c;
+  ev_io_start(EV_DEFAULT, &c->rev);
+
+  ev_timer_init(&c->timer, timer_cb, 0., 0.);
+  c->timer.data = c;
+
+  return 0;
+}
+
+static void client_free(struct client *c) {
+  ngtcp2_conn_del(c->conn);
+  gnutls_deinit(c->session);
+  gnutls_certificate_free_credentials(c->cred);
+}
+
+int main(void) {
+  struct client c;
+
+  if (client_init(&c) != 0) {
+    exit(EXIT_FAILURE);
+  }
+
+  if (client_write(&c) != 0) {
+    exit(EXIT_FAILURE);
+  }
+
+  ev_run(EV_DEFAULT, 0);
+
+  client_free(&c);
+
+  return 0;
+}