nxt_event_conn_... functions and structures have been renamed

to nxt_conn_...

1 files changed, 998 insertions, 0 deletions

diff --git a/src/nxt_conn_proxy.c b/src/nxt_conn_proxy.c
new file mode 100644
index 00000000..dec23684
--- /dev/null
+++ b/src/nxt_conn_proxy.c
@@ -0,0 +1,998 @@
+
+/*
+ * Copyright (C) Igor Sysoev
+ * Copyright (C) NGINX, Inc.
+ */
+
+#include <nxt_main.h>
+
+
+static void nxt_conn_proxy_client_buffer_alloc(nxt_task_t *task, void *obj,
+    void *data);
+static void nxt_conn_proxy_peer_connect(nxt_task_t *task, void *obj,
+    void *data);
+static void nxt_conn_proxy_connected(nxt_task_t *task, void *obj, void *data);
+static void nxt_conn_proxy_peer_read(nxt_task_t *task, void *obj, void *data);
+static void nxt_conn_proxy_client_read_ready(nxt_task_t *task, void *obj,
+    void *data);
+static void nxt_conn_proxy_peer_read_ready(nxt_task_t *task, void *obj,
+    void *data);
+static void nxt_conn_proxy_read_process(nxt_task_t *task, nxt_conn_proxy_t *p,
+    nxt_conn_t *source, nxt_conn_t *sink);
+static void nxt_conn_proxy_write_add(nxt_conn_t *c, nxt_buf_t *b);
+static void nxt_conn_proxy_read(nxt_task_t *task, void *obj, void *data);
+static void nxt_conn_proxy_client_write_ready(nxt_task_t *task, void *obj,
+    void *data);
+static void nxt_conn_proxy_peer_write_ready(nxt_task_t *task, void *obj,
+    void *data);
+static void nxt_conn_proxy_write_process(nxt_task_t *task, nxt_conn_proxy_t *p,
+    nxt_conn_t *sink, nxt_conn_t *source);
+static void nxt_conn_proxy_read_add(nxt_conn_t *c, nxt_buf_t *b);
+static void nxt_conn_proxy_close(nxt_task_t *task, void *obj, void *data);
+static void nxt_conn_proxy_error(nxt_task_t *task, void *obj, void *data);
+static void nxt_conn_proxy_read_timeout(nxt_task_t *task, void *obj,
+    void *data);
+static void nxt_conn_proxy_write_timeout(nxt_task_t *task, void *obj,
+    void *data);
+static nxt_msec_t nxt_conn_proxy_timeout_value(nxt_conn_t *c, uintptr_t data);
+static void nxt_conn_proxy_refused(nxt_task_t *task, void *obj, void *data);
+static void nxt_conn_proxy_reconnect_handler(nxt_task_t *task, void *obj,
+    void *data);
+static void nxt_conn_proxy_shutdown(nxt_task_t *task, nxt_conn_proxy_t *p,
+    nxt_conn_t *source, nxt_conn_t *sink);
+static void nxt_conn_proxy_read_error(nxt_task_t *task, void *obj, void *data);
+static void nxt_conn_proxy_write_error(nxt_task_t *task, void *obj, void *data);
+static void nxt_conn_proxy_complete(nxt_task_t *task, nxt_conn_proxy_t *p);
+static void nxt_conn_proxy_completion(nxt_task_t *task, void *obj, void *data);
+
+
+static const nxt_conn_state_t  nxt_conn_proxy_client_wait_state;
+static const nxt_conn_state_t  nxt_conn_proxy_client_first_read_state;
+static const nxt_conn_state_t  nxt_conn_proxy_peer_connect_state;
+static const nxt_conn_state_t  nxt_conn_proxy_peer_wait_state;
+static const nxt_conn_state_t  nxt_conn_proxy_client_read_state;
+static const nxt_conn_state_t  nxt_conn_proxy_peer_read_state;
+static const nxt_conn_state_t  nxt_conn_proxy_client_write_state;
+static const nxt_conn_state_t  nxt_conn_proxy_peer_write_state;
+
+
+nxt_conn_proxy_t *
+nxt_conn_proxy_create(nxt_conn_t *client)
+{
+    nxt_conn_t        *peer;
+    nxt_thread_t      *thr;
+    nxt_conn_proxy_t  *p;
+
+    p = nxt_mem_zalloc(client->mem_pool, sizeof(nxt_conn_proxy_t));
+    if (nxt_slow_path(p == NULL)) {
+        return NULL;
+    }
+
+    peer = nxt_conn_create(client->mem_pool, client->socket.task);
+    if (nxt_slow_path(peer == NULL)) {
+        return NULL;
+    }
+
+    thr = nxt_thread();
+
+    client->read_work_queue = &thr->engine->read_work_queue;
+    client->write_work_queue = &thr->engine->write_work_queue;
+    client->socket.read_work_queue = &thr->engine->read_work_queue;
+    client->socket.write_work_queue = &thr->engine->write_work_queue;
+    peer->socket.read_work_queue = &thr->engine->read_work_queue;
+    peer->socket.write_work_queue = &thr->engine->write_work_queue;
+
+    peer->socket.data = client->socket.data;
+
+    peer->read_work_queue = client->read_work_queue;
+    peer->write_work_queue = client->write_work_queue;
+    peer->read_timer.work_queue = client->read_work_queue;
+    peer->write_timer.work_queue = client->write_work_queue;
+
+    p->client = client;
+    p->peer = peer;
+
+    return p;
+}
+
+
+void
+nxt_conn_proxy(nxt_task_t *task, nxt_conn_proxy_t *p)
+{
+    nxt_conn_t  *peer;
+
+    /*
+     * Peer read event: not connected, disabled.
+     * Peer write event: not connected, disabled.
+     */
+
+    if (p->client_wait_timeout == 0) {
+        /*
+         * Peer write event: waiting for connection
+         * to be established with connect_timeout.
+         */
+        peer = p->peer;
+        peer->write_state = &nxt_conn_proxy_peer_connect_state;
+
+        nxt_conn_connect(task->thread->engine, peer);
+    }
+
+    /*
+     * Client read event: waiting for client data with
+     * client_wait_timeout before buffer allocation.
+     */
+    p->client->read_state = &nxt_conn_proxy_client_wait_state;
+
+    nxt_conn_wait(p->client);
+}
+
+
+static const nxt_conn_state_t  nxt_conn_proxy_client_wait_state
+    nxt_aligned(64) =
+{
+    .ready_handler = nxt_conn_proxy_client_buffer_alloc,
+    .close_handler = nxt_conn_proxy_close,
+    .error_handler = nxt_conn_proxy_error,
+
+    .timer_handler = nxt_conn_proxy_read_timeout,
+    .timer_value = nxt_conn_proxy_timeout_value,
+    .timer_data = offsetof(nxt_conn_proxy_t, client_wait_timeout),
+};
+
+
+static void
+nxt_conn_proxy_client_buffer_alloc(nxt_task_t *task, void *obj, void *data)
+{
+    nxt_buf_t         *b;
+    nxt_conn_t        *client;
+    nxt_conn_proxy_t  *p;
+
+    client = obj;
+    p = data;
+
+    nxt_debug(task, "conn proxy client first read fd:%d", client->socket.fd);
+
+    b = nxt_buf_mem_alloc(client->mem_pool, p->client_buffer_size,
+                          NXT_MEM_BUF_CUTBACK | NXT_MEM_BUF_USABLE);
+
+    if (nxt_slow_path(b == NULL)) {
+        /* An error completion. */
+        nxt_conn_proxy_complete(task, p);
+        return;
+    }
+
+    p->client_buffer = b;
+    client->read = b;
+
+    if (p->peer->socket.fd != -1) {
+        /*
+         * Client read event: waiting, no timeout.
+         * Client write event: blocked.
+         * Peer read event: disabled.
+         * Peer write event: waiting for connection to be established
+         * or blocked after the connection has established.
+         */
+        client->read_state = &nxt_conn_proxy_client_read_state;
+
+    } else {
+        /*
+         * Client read event: waiting for data with client_wait_timeout
+         * before connecting to a peer.
+         * Client write event: blocked.
+         * Peer read event: not connected, disabled.
+         * Peer write event: not connected, disabled.
+         */
+        client->read_state = &nxt_conn_proxy_client_first_read_state;
+    }
+
+    nxt_conn_read(task->thread->engine, client);
+}
+
+
+static const nxt_conn_state_t  nxt_conn_proxy_client_first_read_state
+    nxt_aligned(64) =
+{
+    .ready_handler = nxt_conn_proxy_peer_connect,
+    .close_handler = nxt_conn_proxy_close,
+    .error_handler = nxt_conn_proxy_error,
+
+    .timer_handler = nxt_conn_proxy_read_timeout,
+    .timer_value = nxt_conn_proxy_timeout_value,
+    .timer_data = offsetof(nxt_conn_proxy_t, client_wait_timeout),
+    .timer_autoreset = 1,
+};
+
+
+static void
+nxt_conn_proxy_peer_connect(nxt_task_t *task, void *obj, void *data)
+{
+    nxt_conn_t        *client;
+    nxt_conn_proxy_t  *p;
+
+    client = obj;
+    p = data;
+
+    /*
+     * Client read event: waiting, no timeout.
+     * Client write event: blocked.
+     * Peer read event: disabled.
+     * Peer write event: waiting for connection to be established
+     * with connect_timeout.
+     */
+    client->read_state = &nxt_conn_proxy_client_read_state;
+
+    p->peer->write_state = &nxt_conn_proxy_peer_connect_state;
+
+    nxt_conn_connect(task->thread->engine, p->peer);
+}
+
+
+static const nxt_conn_state_t  nxt_conn_proxy_peer_connect_state
+    nxt_aligned(64) =
+{
+    .ready_handler = nxt_conn_proxy_connected,
+    .close_handler = nxt_conn_proxy_refused,
+    .error_handler = nxt_conn_proxy_error,
+
+    .timer_handler = nxt_conn_proxy_write_timeout,
+    .timer_value = nxt_conn_proxy_timeout_value,
+    .timer_data = offsetof(nxt_conn_proxy_t, connect_timeout),
+    .timer_autoreset = 1,
+};
+
+
+static void
+nxt_conn_proxy_connected(nxt_task_t *task, void *obj, void *data)
+{
+    nxt_conn_t        *client, *peer;
+    nxt_conn_proxy_t  *p;
+
+    peer = obj;
+    p = data;
+
+    nxt_debug(task, "conn proxy connected fd:%d", peer->socket.fd);
+
+    p->connected = 1;
+
+    nxt_conn_tcp_nodelay_on(task, peer);
+    nxt_conn_tcp_nodelay_on(task, p->client);
+
+    /* Peer read event: waiting with peer_wait_timeout.  */
+
+    peer->read_state = &nxt_conn_proxy_peer_wait_state;
+    peer->write_state = &nxt_conn_proxy_peer_write_state;
+
+    nxt_conn_wait(peer);
+
+    if (p->client_buffer != NULL) {
+        client = p->client;
+
+        client->read_state = &nxt_conn_proxy_client_read_state;
+        client->write_state = &nxt_conn_proxy_client_write_state;
+        /*
+         * Send a client read data to the connected peer.
+         * Client write event: blocked.
+         */
+        nxt_conn_proxy_read_process(task, p, client, peer);
+    }
+}
+
+
+static const nxt_conn_state_t  nxt_conn_proxy_peer_wait_state
+    nxt_aligned(64) =
+{
+    .ready_handler = nxt_conn_proxy_peer_read,
+    .close_handler = nxt_conn_proxy_close,
+    .error_handler = nxt_conn_proxy_error,
+
+    .timer_handler = nxt_conn_proxy_read_timeout,
+    .timer_value = nxt_conn_proxy_timeout_value,
+    .timer_data = offsetof(nxt_conn_proxy_t, peer_wait_timeout),
+};
+
+
+static void
+nxt_conn_proxy_peer_read(nxt_task_t *task, void *obj, void *data)
+{
+    nxt_buf_t         *b;
+    nxt_conn_t        *peer;
+    nxt_conn_proxy_t  *p;
+
+    peer = obj;
+    p = data;
+
+    nxt_debug(task, "conn proxy peer read fd:%d", peer->socket.fd);
+
+    b = nxt_buf_mem_alloc(peer->mem_pool, p->peer_buffer_size,
+                          NXT_MEM_BUF_CUTBACK | NXT_MEM_BUF_USABLE);
+
+    if (nxt_slow_path(b == NULL)) {
+        /* An error completion. */
+        nxt_conn_proxy_complete(task, p);
+        return;
+    }
+
+    p->peer_buffer = b;
+    peer->read = b;
+
+    p->client->write_state = &nxt_conn_proxy_client_write_state;
+    peer->read_state = &nxt_conn_proxy_peer_read_state;
+    peer->write_state = &nxt_conn_proxy_peer_write_state;
+
+    /*
+     * Client read event: waiting, no timeout.
+     * Client write event: blocked.
+     * Peer read event: waiting with possible peer_wait_timeout.
+     * Peer write event: blocked.
+     */
+    nxt_conn_read(task->thread->engine, peer);
+}
+
+
+static const nxt_conn_state_t  nxt_conn_proxy_client_read_state
+    nxt_aligned(64) =
+{
+    .ready_handler = nxt_conn_proxy_client_read_ready,
+    .close_handler = nxt_conn_proxy_close,
+    .error_handler = nxt_conn_proxy_read_error,
+};
+
+
+static void
+nxt_conn_proxy_client_read_ready(nxt_task_t *task, void *obj, void *data)
+{
+    nxt_conn_t        *client;
+    nxt_conn_proxy_t  *p;
+
+    client = obj;
+    p = data;
+
+    nxt_debug(task, "conn proxy client read ready fd:%d", client->socket.fd);
+
+    nxt_conn_proxy_read_process(task, p, client, p->peer);
+}
+
+
+static const nxt_conn_state_t  nxt_conn_proxy_peer_read_state
+    nxt_aligned(64) =
+{
+    .ready_handler = nxt_conn_proxy_peer_read_ready,
+    .close_handler = nxt_conn_proxy_close,
+    .error_handler = nxt_conn_proxy_read_error,
+};
+
+
+static void
+nxt_conn_proxy_peer_read_ready(nxt_task_t *task, void *obj, void *data)
+{
+    nxt_conn_t        *peer;
+    nxt_conn_proxy_t  *p;
+
+    peer = obj;
+    p = data;
+
+    nxt_debug(task, "conn proxy peer read ready fd:%d", peer->socket.fd);
+
+    nxt_conn_proxy_read_process(task, p, peer, p->client);
+}
+
+
+static void
+nxt_conn_proxy_read_process(nxt_task_t *task, nxt_conn_proxy_t *p,
+    nxt_conn_t *source, nxt_conn_t *sink)
+{
+    nxt_buf_t  *rb, *wb;
+
+    if (sink->socket.error != 0) {
+        nxt_debug(task, "conn proxy sink fd:%d error:%d",
+                  sink->socket.fd, sink->socket.error);
+
+        nxt_conn_proxy_write_error(task, sink, sink->socket.data);
+        return;
+    }
+
+    while (source->read != NULL) {
+
+        rb = source->read;
+
+        if (rb->mem.pos != rb->mem.free) {
+
+            /* Add a read part to a write chain. */
+
+            wb = nxt_buf_mem_alloc(source->mem_pool, 0, 0);
+            if (wb == NULL) {
+                /* An error completion. */
+                nxt_conn_proxy_complete(task, p);
+                return;
+            }
+
+            wb->mem.pos = rb->mem.pos;
+            wb->mem.free = rb->mem.free;
+            wb->mem.start = rb->mem.pos;
+            wb->mem.end = rb->mem.free;
+
+            rb->mem.pos = rb->mem.free;
+            rb->mem.start = rb->mem.free;
+
+            nxt_conn_proxy_write_add(sink, wb);
+        }
+
+        if (rb->mem.start != rb->mem.end) {
+            nxt_work_queue_add(source->read_work_queue, nxt_conn_proxy_read,
+                               task, source, source->socket.data);
+            break;
+        }
+
+        source->read = rb->next;
+        nxt_buf_free(source->mem_pool, rb);
+    }
+
+    if (p->connected) {
+        nxt_conn_write(task->thread->engine, sink);
+    }
+}
+
+
+static void
+nxt_conn_proxy_write_add(nxt_conn_t *c, nxt_buf_t *b)
+{
+    nxt_buf_t  *first, *second, *prev;
+
+    first = c->write;
+
+    if (first == NULL) {
+        c->write = b;
+        return;
+    }
+
+    /*
+     * A event conn proxy maintains a buffer per each direction.
+     * The buffer is divided by read and write parts.  These parts are
+     * linked in buffer chains.  There can be no more than two buffers
+     * in write chain at any time, because an added buffer is coalesced
+     * with the last buffer if possible.
+     */
+
+    second = first->next;
+
+    if (second == NULL) {
+
+        if (first->mem.end != b->mem.start) {
+            first->next = b;
+            return;
+        }
+
+        /*
+         * The first buffer is just before the added buffer, so
+         * expand the first buffer to the end of the added buffer.
+         */
+        prev = first;
+
+    } else {
+        if (second->mem.end != b->mem.start) {
+            nxt_thread_log_alert("event conn proxy write: second buffer end:%p "
+                                 "is not equal to added buffer start:%p",
+                                 second->mem.end, b->mem.start);
+            return;
+        }
+
+        /*
+         * "second->mem.end == b->mem.start" must be always true here,
+         * that is the second buffer is just before the added buffer,
+         * so expand the second buffer to the end of added buffer.
+         */
+        prev = second;
+    }
+
+    prev->mem.free = b->mem.end;
+    prev->mem.end = b->mem.end;
+
+    nxt_buf_free(c->mem_pool, b);
+}
+
+
+static void
+nxt_conn_proxy_read(nxt_task_t *task, void *obj, void *data)
+{
+    nxt_conn_t        *source, *sink;
+    nxt_conn_proxy_t  *p;
+
+    source = obj;
+    p = data;
+
+    nxt_debug(task, "conn proxy read fd:%d", source->socket.fd);
+
+    if (!source->socket.closed) {
+        sink = (source == p->client) ? p->peer : p->client;
+
+        if (sink->socket.error == 0) {
+            nxt_conn_read(task->thread->engine, source);
+        }
+    }
+}
+
+
+static const nxt_conn_state_t  nxt_conn_proxy_client_write_state
+    nxt_aligned(64) =
+{
+    .ready_handler = nxt_conn_proxy_client_write_ready,
+    .error_handler = nxt_conn_proxy_write_error,
+
+    .timer_handler = nxt_conn_proxy_write_timeout,
+    .timer_value = nxt_conn_proxy_timeout_value,
+    .timer_data = offsetof(nxt_conn_proxy_t, client_write_timeout),
+    .timer_autoreset = 1,
+};
+
+
+static void
+nxt_conn_proxy_client_write_ready(nxt_task_t *task, void *obj, void *data)
+{
+    nxt_conn_t        *client;
+    nxt_conn_proxy_t  *p;
+
+    client = obj;
+    p = data;
+
+    nxt_debug(task, "conn proxy client write ready fd:%d", client->socket.fd);
+
+    nxt_conn_proxy_write_process(task, p, client, p->peer);
+}
+
+
+static const nxt_conn_state_t  nxt_conn_proxy_peer_write_state
+    nxt_aligned(64) =
+{
+    .ready_handler = nxt_conn_proxy_peer_write_ready,
+    .error_handler = nxt_conn_proxy_write_error,
+
+    .timer_handler = nxt_conn_proxy_write_timeout,
+    .timer_value = nxt_conn_proxy_timeout_value,
+    .timer_data = offsetof(nxt_conn_proxy_t, peer_write_timeout),
+    .timer_autoreset = 1,
+};
+
+
+static void
+nxt_conn_proxy_peer_write_ready(nxt_task_t *task, void *obj, void *data)
+{
+    nxt_conn_t        *peer;
+    nxt_conn_proxy_t  *p;
+
+    peer = obj;
+    p = data;
+
+    nxt_debug(task, "conn proxy peer write ready fd:%d", peer->socket.fd);
+
+    nxt_conn_proxy_write_process(task, p, peer, p->client);
+}
+
+
+static void
+nxt_conn_proxy_write_process(nxt_task_t *task, nxt_conn_proxy_t *p,
+    nxt_conn_t *sink, nxt_conn_t *source)
+{
+    nxt_buf_t  *rb, *wb;
+
+    while (sink->write != NULL) {
+
+        wb = sink->write;
+
+        if (nxt_buf_is_sync(wb)) {
+
+            /* A sync buffer marks the end of stream. */
+
+            sink->write = NULL;
+            nxt_buf_free(sink->mem_pool, wb);
+            nxt_conn_proxy_shutdown(task, p, source, sink);
+            return;
+        }
+
+        if (wb->mem.start != wb->mem.pos) {
+
+            /* Add a written part to a read chain. */
+
+            rb = nxt_buf_mem_alloc(sink->mem_pool, 0, 0);
+            if (rb == NULL) {
+                /* An error completion. */
+                nxt_conn_proxy_complete(task, p);
+                return;
+            }
+
+            rb->mem.pos = wb->mem.start;
+            rb->mem.free = wb->mem.start;
+            rb->mem.start = wb->mem.start;
+            rb->mem.end = wb->mem.pos;
+
+            wb->mem.start = wb->mem.pos;
+
+            nxt_conn_proxy_read_add(source, rb);
+        }
+
+        if (wb->mem.pos != wb->mem.free) {
+            nxt_conn_write(task->thread->engine, sink);
+
+            break;
+        }
+
+        sink->write = wb->next;
+        nxt_buf_free(sink->mem_pool, wb);
+    }
+
+    nxt_work_queue_add(source->read_work_queue, nxt_conn_proxy_read,
+                       task, source, source->socket.data);
+}
+
+
+static void
+nxt_conn_proxy_read_add(nxt_conn_t *c, nxt_buf_t *b)
+{
+    nxt_buf_t  *first, *second;
+
+    first = c->read;
+
+    if (first == NULL) {
+        c->read = b;
+        return;
+    }
+
+    /*
+     * A event conn proxy maintains a buffer per each direction.
+     * The buffer is divided by read and write parts.  These parts are
+     * linked in buffer chains.  There can be no more than two buffers
+     * in read chain at any time, because an added buffer is coalesced
+     * with the last buffer if possible.  The first and the second
+     * buffers are also coalesced if possible.
+     */
+
+    second = first->next;
+
+    if (second == NULL) {
+
+        if (first->mem.start == b->mem.end) {
+            /*
+             * The added buffer is just before the first buffer, so expand
+             * the first buffer to the beginning of the added buffer.
+             */
+            first->mem.pos = b->mem.start;
+            first->mem.free = b->mem.start;
+            first->mem.start = b->mem.start;
+
+        } else if (first->mem.end == b->mem.start) {
+            /*
+             * The added buffer is just after the first buffer, so
+             * expand the first buffer to the end of the added buffer.
+             */
+            first->mem.end = b->mem.end;
+
+        } else {
+            first->next = b;
+            return;
+        }
+
+    } else {
+        if (second->mem.end != b->mem.start) {
+            nxt_thread_log_alert("event conn proxy read: second buffer end:%p "
+                                 "is not equal to added buffer start:%p",
+                                 second->mem.end, b->mem.start);
+            return;
+        }
+
+        /*
+         * The added buffer is just after the second buffer, so
+         * expand the second buffer to the end of the added buffer.
+         */
+        second->mem.end = b->mem.end;
+
+        if (first->mem.start == second->mem.end) {
+            /*
+             * The second buffer is just before the first buffer, so expand
+             * the first buffer to the beginning of the second buffer.
+             */
+            first->mem.pos = second->mem.start;
+            first->mem.free = second->mem.start;
+            first->mem.start = second->mem.start;
+            first->next = NULL;
+
+            nxt_buf_free(c->mem_pool, second);
+        }
+    }
+
+    nxt_buf_free(c->mem_pool, b);
+}
+
+
+static void
+nxt_conn_proxy_close(nxt_task_t *task, void *obj, void *data)
+{
+    nxt_buf_t         *b;
+    nxt_conn_t        *source, *sink;
+    nxt_conn_proxy_t  *p;
+
+    source = obj;
+    p = data;
+
+    nxt_debug(task, "conn proxy close fd:%d", source->socket.fd);
+
+    sink = (source == p->client) ? p->peer : p->client;
+
+    if (sink->write == NULL) {
+        nxt_conn_proxy_shutdown(task, p, source, sink);
+        return;
+    }
+
+    b = nxt_buf_sync_alloc(source->mem_pool, 0);
+    if (b == NULL) {
+        /* An error completion. */
+        nxt_conn_proxy_complete(task, p);
+        return;
+    }
+
+    nxt_buf_chain_add(&sink->write, b);
+}
+
+
+static void
+nxt_conn_proxy_error(nxt_task_t *task, void *obj, void *data)
+{
+    nxt_conn_t        *c;
+    nxt_conn_proxy_t  *p;
+
+    c = obj;
+    p = data;
+
+    nxt_debug(task, "conn proxy error fd:%d", c->socket.fd);
+
+    nxt_conn_proxy_close(task, c, p);
+}
+
+
+static void
+nxt_conn_proxy_read_timeout(nxt_task_t *task, void *obj, void *data)
+{
+    nxt_conn_t   *c;
+    nxt_timer_t  *timer;
+
+    timer = obj;
+
+    c = nxt_read_timer_conn(timer);
+    c->socket.timedout = 1;
+    c->socket.closed = 1;
+
+    nxt_debug(task, "conn proxy read timeout fd:%d", c->socket.fd);
+
+    nxt_conn_proxy_close(task, c, c->socket.data);
+}
+
+
+static void
+nxt_conn_proxy_write_timeout(nxt_task_t *task, void *obj, void *data)
+{
+    nxt_conn_t   *c;
+    nxt_timer_t  *timer;
+
+    timer = obj;
+
+    c = nxt_write_timer_conn(timer);
+    c->socket.timedout = 1;
+    c->socket.closed = 1;
+
+    nxt_debug(task, "conn proxy write timeout fd:%d", c->socket.fd);
+
+    nxt_conn_proxy_close(task, c, c->socket.data);
+}
+
+
+static nxt_msec_t
+nxt_conn_proxy_timeout_value(nxt_conn_t *c, uintptr_t data)
+{
+    nxt_msec_t        *timer;
+    nxt_conn_proxy_t  *p;
+
+    p = c->socket.data;
+
+    timer = (nxt_msec_t *) ((char *) p + data);
+
+    return *timer;
+}
+
+
+static void
+nxt_conn_proxy_refused(nxt_task_t *task, void *obj, void *data)
+{
+    nxt_conn_t        *peer;
+    nxt_conn_proxy_t  *p;
+
+    peer = obj;
+    p = data;
+
+    nxt_debug(task, "conn proxy refused fd:%d", peer->socket.fd);
+
+    if (p->retries == 0) {
+        /* An error completion. */
+        nxt_conn_proxy_complete(task, p);
+        return;
+    }
+
+    p->retries--;
+
+    nxt_socket_close(task, peer->socket.fd);
+    peer->socket.fd = -1;
+    peer->socket.error = 0;
+
+    p->delayed = 1;
+
+    peer->write_timer.handler = nxt_conn_proxy_reconnect_handler;
+    nxt_timer_add(task->thread->engine, &peer->write_timer,
+                  p->reconnect_timeout);
+}
+
+
+static void
+nxt_conn_proxy_reconnect_handler(nxt_task_t *task, void *obj, void *data)
+{
+    nxt_conn_t        *peer;
+    nxt_timer_t       *timer;
+    nxt_conn_proxy_t  *p;
+
+    timer = obj;
+
+    nxt_debug(task, "conn proxy reconnect timer");
+
+    peer = nxt_write_timer_conn(timer);
+    p = peer->socket.data;
+
+    if (p->client->socket.closed) {
+        nxt_conn_proxy_complete(task, p);
+        return;
+    }
+
+    p->delayed = 0;
+
+    peer->write_state = &nxt_conn_proxy_peer_connect_state;
+    /*
+     * Peer read event: disabled.
+     * Peer write event: waiting for connection with connect_timeout.
+     */
+    nxt_conn_connect(task->thread->engine, peer);
+}
+
+
+static void
+nxt_conn_proxy_shutdown(nxt_task_t *task, nxt_conn_proxy_t *p,
+    nxt_conn_t *source, nxt_conn_t *sink)
+{
+    nxt_buf_t  *b;
+
+    nxt_debug(source->socket.task,
+              "conn proxy shutdown source fd:%d cl:%d err:%d",
+              source->socket.fd, source->socket.closed, source->socket.error);
+
+    nxt_debug(sink->socket.task,
+              "conn proxy shutdown sink fd:%d cl:%d err:%d",
+              sink->socket.fd, sink->socket.closed, sink->socket.error);
+
+    if (!p->connected || p->delayed) {
+        nxt_conn_proxy_complete(task, p);
+        return;
+    }
+
+    if (sink->socket.error == 0 && !sink->socket.closed) {
+        sink->socket.shutdown = 1;
+        nxt_socket_shutdown(task, sink->socket.fd, SHUT_WR);
+    }
+
+    if (sink->socket.error != 0
+        || (sink->socket.closed && source->write == NULL))
+    {
+        /* The opposite direction also has been already closed. */
+        nxt_conn_proxy_complete(task, p);
+        return;
+    }
+
+    nxt_debug(source->socket.task, "free source buffer");
+
+    /* Free the direction's buffer. */
+    b = (source == p->client) ? p->client_buffer : p->peer_buffer;
+    nxt_mem_free(source->mem_pool, b);
+}
+
+
+static void
+nxt_conn_proxy_read_error(nxt_task_t *task, void *obj, void *data)
+{
+    nxt_conn_t        *c;
+    nxt_conn_proxy_t  *p;
+
+    c = obj;
+    p = data;
+
+    nxt_debug(task, "conn proxy read error fd:%d", c->socket.fd);
+
+    nxt_conn_proxy_close(task, c, p);
+}
+
+
+static void
+nxt_conn_proxy_write_error(nxt_task_t *task, void *obj, void *data)
+{
+    nxt_conn_t        *source, *sink;
+    nxt_conn_proxy_t  *p;
+
+    sink = obj;
+    p = data;
+
+    nxt_debug(task, "conn proxy write error fd:%d", sink->socket.fd);
+
+    /* Clear data for the direction sink. */
+    sink->write = NULL;
+
+    /* Block the direction source. */
+    source = (sink == p->client) ? p->peer : p->client;
+    nxt_fd_event_block_read(task->thread->engine, &source->socket);
+
+    if (source->write == NULL) {
+        /*
+         * There is no data for the opposite direction and
+         * the next read from the sink will most probably fail.
+         */
+        nxt_conn_proxy_complete(task, p);
+    }
+}
+
+
+static const nxt_conn_state_t  nxt_conn_proxy_close_state
+    nxt_aligned(64) =
+{
+    .ready_handler = nxt_conn_proxy_completion,
+};
+
+
+static void
+nxt_conn_proxy_complete(nxt_task_t *task, nxt_conn_proxy_t *p)
+{
+    nxt_event_engine_t  *engine;
+
+    engine = task->thread->engine;
+
+    nxt_debug(p->client->socket.task, "conn proxy complete %d:%d",
+              p->client->socket.fd, p->peer->socket.fd);
+
+    if (p->delayed) {
+        p->delayed = 0;
+        nxt_queue_remove(&p->peer->link);
+    }
+
+    if (p->client->socket.fd != -1) {
+        p->retain = 1;
+        p->client->write_state = &nxt_conn_proxy_close_state;
+        nxt_conn_close(engine, p->client);
+    }
+
+    if (p->peer->socket.fd != -1) {
+        p->retain++;
+        p->peer->write_state = &nxt_conn_proxy_close_state;
+        nxt_conn_close(engine, p->peer);
+    }
+}
+
+
+static void
+nxt_conn_proxy_completion(nxt_task_t *task, void *obj, void *data)
+{
+    nxt_conn_proxy_t  *p;
+
+    p = data;
+
+    nxt_debug(p->client->socket.task, "conn proxy completion %d:%d:%d",
+              p->retain, p->client->socket.fd, p->peer->socket.fd);
+
+    p->retain--;
+
+    if (p->retain == 0) {
+        nxt_mem_free(p->client->mem_pool, p->client_buffer);
+        nxt_mem_free(p->client->mem_pool, p->peer_buffer);
+
+        p->completion_handler(task, p, NULL);
+    }
+}