1 files changed, 453 insertions, 0 deletions

diff --git a/src/connection.c b/src/connection.c
new file mode 100644
index 0000000..f61ed24
--- /dev/null
+++ b/src/connection.c
@@ -0,0 +1,453 @@
+/*
+ * Copyright (c) 2019, Redis Labs
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *   * Redistributions of source code must retain the above copyright notice,
+ *     this list of conditions and the following disclaimer.
+ *   * Redistributions in binary form must reproduce the above copyright
+ *     notice, this list of conditions and the following disclaimer in the
+ *     documentation and/or other materials provided with the distribution.
+ *   * Neither the name of Redis nor the names of its contributors may be used
+ *     to endorse or promote products derived from this software without
+ *     specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "server.h"
+#include "connhelpers.h"
+
+/* The connections module provides a lean abstraction of network connections
+ * to avoid direct socket and async event management across the Redis code base.
+ *
+ * It does NOT provide advanced connection features commonly found in similar
+ * libraries such as complete in/out buffer management, throttling, etc. These
+ * functions remain in networking.c.
+ *
+ * The primary goal is to allow transparent handling of TCP and TLS based
+ * connections. To do so, connections have the following properties:
+ *
+ * 1. A connection may live before its corresponding socket exists.  This
+ *    allows various context and configuration setting to be handled before
+ *    establishing the actual connection.
+ * 2. The caller may register/unregister logical read/write handlers to be
+ *    called when the connection has data to read from/can accept writes.
+ *    These logical handlers may or may not correspond to actual AE events,
+ *    depending on the implementation (for TCP they are; for TLS they aren't).
+ */
+
+ConnectionType CT_Socket;
+
+/* When a connection is created we must know its type already, but the
+ * underlying socket may or may not exist:
+ *
+ * - For accepted connections, it exists as we do not model the listen/accept
+ *   part; So caller calls connCreateSocket() followed by connAccept().
+ * - For outgoing connections, the socket is created by the connection module
+ *   itself; So caller calls connCreateSocket() followed by connConnect(),
+ *   which registers a connect callback that fires on connected/error state
+ *   (and after any transport level handshake was done).
+ *
+ * NOTE: An earlier version relied on connections being part of other structs
+ * and not independently allocated. This could lead to further optimizations
+ * like using container_of(), etc.  However it was discontinued in favor of
+ * this approach for these reasons:
+ *
+ * 1. In some cases conns are created/handled outside the context of the
+ * containing struct, in which case it gets a bit awkward to copy them.
+ * 2. Future implementations may wish to allocate arbitrary data for the
+ * connection.
+ * 3. The container_of() approach is anyway risky because connections may
+ * be embedded in different structs, not just client.
+ */
+
+connection *connCreateSocket() {
+    connection *conn = zcalloc(sizeof(connection));
+    conn->type = &CT_Socket;
+    conn->fd = -1;
+
+    return conn;
+}
+
+/* Create a new socket-type connection that is already associated with
+ * an accepted connection.
+ *
+ * The socket is not ready for I/O until connAccept() was called and
+ * invoked the connection-level accept handler.
+ *
+ * Callers should use connGetState() and verify the created connection
+ * is not in an error state (which is not possible for a socket connection,
+ * but could but possible with other protocols).
+ */
+connection *connCreateAcceptedSocket(int fd) {
+    connection *conn = connCreateSocket();
+    conn->fd = fd;
+    conn->state = CONN_STATE_ACCEPTING;
+    return conn;
+}
+
+static int connSocketConnect(connection *conn, const char *addr, int port, const char *src_addr,
+        ConnectionCallbackFunc connect_handler) {
+    int fd = anetTcpNonBlockBestEffortBindConnect(NULL,addr,port,src_addr);
+    if (fd == -1) {
+        conn->state = CONN_STATE_ERROR;
+        conn->last_errno = errno;
+        return C_ERR;
+    }
+
+    conn->fd = fd;
+    conn->state = CONN_STATE_CONNECTING;
+
+    conn->conn_handler = connect_handler;
+    aeCreateFileEvent(server.el, conn->fd, AE_WRITABLE,
+            conn->type->ae_handler, conn);
+
+    return C_OK;
+}
+
+/* Returns true if a write handler is registered */
+int connHasWriteHandler(connection *conn) {
+    return conn->write_handler != NULL;
+}
+
+/* Returns true if a read handler is registered */
+int connHasReadHandler(connection *conn) {
+    return conn->read_handler != NULL;
+}
+
+/* Associate a private data pointer with the connection */
+void connSetPrivateData(connection *conn, void *data) {
+    conn->private_data = data;
+}
+
+/* Get the associated private data pointer */
+void *connGetPrivateData(connection *conn) {
+    return conn->private_data;
+}
+
+/* ------ Pure socket connections ------- */
+
+/* A very incomplete list of implementation-specific calls.  Much of the above shall
+ * move here as we implement additional connection types.
+ */
+
+/* Close the connection and free resources. */
+static void connSocketClose(connection *conn) {
+    if (conn->fd != -1) {
+        aeDeleteFileEvent(server.el,conn->fd, AE_READABLE | AE_WRITABLE);
+        close(conn->fd);
+        conn->fd = -1;
+    }
+
+    /* If called from within a handler, schedule the close but
+     * keep the connection until the handler returns.
+     */
+    if (connHasRefs(conn)) {
+        conn->flags |= CONN_FLAG_CLOSE_SCHEDULED;
+        return;
+    }
+
+    zfree(conn);
+}
+
+static int connSocketWrite(connection *conn, const void *data, size_t data_len) {
+    int ret = write(conn->fd, data, data_len);
+    if (ret < 0 && errno != EAGAIN) {
+        conn->last_errno = errno;
+
+        /* Don't overwrite the state of a connection that is not already
+         * connected, not to mess with handler callbacks.
+         */
+        if (errno != EINTR && conn->state == CONN_STATE_CONNECTED)
+            conn->state = CONN_STATE_ERROR;
+    }
+
+    return ret;
+}
+
+static int connSocketWritev(connection *conn, const struct iovec *iov, int iovcnt) {
+    int ret = writev(conn->fd, iov, iovcnt);
+    if (ret < 0 && errno != EAGAIN) {
+        conn->last_errno = errno;
+
+        /* Don't overwrite the state of a connection that is not already
+         * connected, not to mess with handler callbacks.
+         */
+        if (errno != EINTR && conn->state == CONN_STATE_CONNECTED)
+            conn->state = CONN_STATE_ERROR;
+    }
+
+    return ret;
+}
+
+static int connSocketRead(connection *conn, void *buf, size_t buf_len) {
+    int ret = read(conn->fd, buf, buf_len);
+    if (!ret) {
+        conn->state = CONN_STATE_CLOSED;
+    } else if (ret < 0 && errno != EAGAIN) {
+        conn->last_errno = errno;
+
+        /* Don't overwrite the state of a connection that is not already
+         * connected, not to mess with handler callbacks.
+         */
+        if (errno != EINTR && conn->state == CONN_STATE_CONNECTED)
+            conn->state = CONN_STATE_ERROR;
+    }
+
+    return ret;
+}
+
+static int connSocketAccept(connection *conn, ConnectionCallbackFunc accept_handler) {
+    int ret = C_OK;
+
+    if (conn->state != CONN_STATE_ACCEPTING) return C_ERR;
+    conn->state = CONN_STATE_CONNECTED;
+
+    connIncrRefs(conn);
+    if (!callHandler(conn, accept_handler)) ret = C_ERR;
+    connDecrRefs(conn);
+
+    return ret;
+}
+
+/* Register a write handler, to be called when the connection is writable.
+ * If NULL, the existing handler is removed.
+ *
+ * The barrier flag indicates a write barrier is requested, resulting with
+ * CONN_FLAG_WRITE_BARRIER set. This will ensure that the write handler is
+ * always called before and not after the read handler in a single event
+ * loop.
+ */
+static int connSocketSetWriteHandler(connection *conn, ConnectionCallbackFunc func, int barrier) {
+    if (func == conn->write_handler) return C_OK;
+
+    conn->write_handler = func;
+    if (barrier)
+        conn->flags |= CONN_FLAG_WRITE_BARRIER;
+    else
+        conn->flags &= ~CONN_FLAG_WRITE_BARRIER;
+    if (!conn->write_handler)
+        aeDeleteFileEvent(server.el,conn->fd,AE_WRITABLE);
+    else
+        if (aeCreateFileEvent(server.el,conn->fd,AE_WRITABLE,
+                    conn->type->ae_handler,conn) == AE_ERR) return C_ERR;
+    return C_OK;
+}
+
+/* Register a read handler, to be called when the connection is readable.
+ * If NULL, the existing handler is removed.
+ */
+static int connSocketSetReadHandler(connection *conn, ConnectionCallbackFunc func) {
+    if (func == conn->read_handler) return C_OK;
+
+    conn->read_handler = func;
+    if (!conn->read_handler)
+        aeDeleteFileEvent(server.el,conn->fd,AE_READABLE);
+    else
+        if (aeCreateFileEvent(server.el,conn->fd,
+                    AE_READABLE,conn->type->ae_handler,conn) == AE_ERR) return C_ERR;
+    return C_OK;
+}
+
+static const char *connSocketGetLastError(connection *conn) {
+    return strerror(conn->last_errno);
+}
+
+static void connSocketEventHandler(struct aeEventLoop *el, int fd, void *clientData, int mask)
+{
+    UNUSED(el);
+    UNUSED(fd);
+    connection *conn = clientData;
+
+    if (conn->state == CONN_STATE_CONNECTING &&
+            (mask & AE_WRITABLE) && conn->conn_handler) {
+
+        int conn_error = connGetSocketError(conn);
+        if (conn_error) {
+            conn->last_errno = conn_error;
+            conn->state = CONN_STATE_ERROR;
+        } else {
+            conn->state = CONN_STATE_CONNECTED;
+        }
+
+        if (!conn->write_handler) aeDeleteFileEvent(server.el,conn->fd,AE_WRITABLE);
+
+        if (!callHandler(conn, conn->conn_handler)) return;
+        conn->conn_handler = NULL;
+    }
+
+    /* Normally we execute the readable event first, and the writable
+     * event later. This is useful as sometimes we may be able
+     * to serve the reply of a query immediately after processing the
+     * query.
+     *
+     * However if WRITE_BARRIER is set in the mask, our application is
+     * asking us to do the reverse: never fire the writable event
+     * after the readable. In such a case, we invert the calls.
+     * This is useful when, for instance, we want to do things
+     * in the beforeSleep() hook, like fsync'ing a file to disk,
+     * before replying to a client. */
+    int invert = conn->flags & CONN_FLAG_WRITE_BARRIER;
+
+    int call_write = (mask & AE_WRITABLE) && conn->write_handler;
+    int call_read = (mask & AE_READABLE) && conn->read_handler;
+
+    /* Handle normal I/O flows */
+    if (!invert && call_read) {
+        if (!callHandler(conn, conn->read_handler)) return;
+    }
+    /* Fire the writable event. */
+    if (call_write) {
+        if (!callHandler(conn, conn->write_handler)) return;
+    }
+    /* If we have to invert the call, fire the readable event now
+     * after the writable one. */
+    if (invert && call_read) {
+        if (!callHandler(conn, conn->read_handler)) return;
+    }
+}
+
+static int connSocketBlockingConnect(connection *conn, const char *addr, int port, long long timeout) {
+    int fd = anetTcpNonBlockConnect(NULL,addr,port);
+    if (fd == -1) {
+        conn->state = CONN_STATE_ERROR;
+        conn->last_errno = errno;
+        return C_ERR;
+    }
+
+    if ((aeWait(fd, AE_WRITABLE, timeout) & AE_WRITABLE) == 0) {
+        conn->state = CONN_STATE_ERROR;
+        conn->last_errno = ETIMEDOUT;
+    }
+
+    conn->fd = fd;
+    conn->state = CONN_STATE_CONNECTED;
+    return C_OK;
+}
+
+/* Connection-based versions of syncio.c functions.
+ * NOTE: This should ideally be refactored out in favor of pure async work.
+ */
+
+static ssize_t connSocketSyncWrite(connection *conn, char *ptr, ssize_t size, long long timeout) {
+    return syncWrite(conn->fd, ptr, size, timeout);
+}
+
+static ssize_t connSocketSyncRead(connection *conn, char *ptr, ssize_t size, long long timeout) {
+    return syncRead(conn->fd, ptr, size, timeout);
+}
+
+static ssize_t connSocketSyncReadLine(connection *conn, char *ptr, ssize_t size, long long timeout) {
+    return syncReadLine(conn->fd, ptr, size, timeout);
+}
+
+static int connSocketGetType(connection *conn) {
+    (void) conn;
+
+    return CONN_TYPE_SOCKET;
+}
+
+ConnectionType CT_Socket = {
+    .ae_handler = connSocketEventHandler,
+    .close = connSocketClose,
+    .write = connSocketWrite,
+    .writev = connSocketWritev,
+    .read = connSocketRead,
+    .accept = connSocketAccept,
+    .connect = connSocketConnect,
+    .set_write_handler = connSocketSetWriteHandler,
+    .set_read_handler = connSocketSetReadHandler,
+    .get_last_error = connSocketGetLastError,
+    .blocking_connect = connSocketBlockingConnect,
+    .sync_write = connSocketSyncWrite,
+    .sync_read = connSocketSyncRead,
+    .sync_readline = connSocketSyncReadLine,
+    .get_type = connSocketGetType
+};
+
+
+int connGetSocketError(connection *conn) {
+    int sockerr = 0;
+    socklen_t errlen = sizeof(sockerr);
+
+    if (getsockopt(conn->fd, SOL_SOCKET, SO_ERROR, &sockerr, &errlen) == -1)
+        sockerr = errno;
+    return sockerr;
+}
+
+int connPeerToString(connection *conn, char *ip, size_t ip_len, int *port) {
+    if (anetFdToString(conn ? conn->fd : -1, ip, ip_len, port, FD_TO_PEER_NAME) == -1) {
+        if (conn) conn->last_errno = errno;
+        return C_ERR;
+    }
+    return C_OK;
+}
+
+int connSockName(connection *conn, char *ip, size_t ip_len, int *port) {
+    return anetFdToString(conn->fd, ip, ip_len, port, FD_TO_SOCK_NAME);
+}
+
+int connFormatFdAddr(connection *conn, char *buf, size_t buf_len, int fd_to_str_type) {
+    return anetFormatFdAddr(conn ? conn->fd : -1, buf, buf_len, fd_to_str_type);
+}
+
+int connBlock(connection *conn) {
+    if (conn->fd == -1) return C_ERR;
+    return anetBlock(NULL, conn->fd);
+}
+
+int connNonBlock(connection *conn) {
+    if (conn->fd == -1) return C_ERR;
+    return anetNonBlock(NULL, conn->fd);
+}
+
+int connEnableTcpNoDelay(connection *conn) {
+    if (conn->fd == -1) return C_ERR;
+    return anetEnableTcpNoDelay(NULL, conn->fd);
+}
+
+int connDisableTcpNoDelay(connection *conn) {
+    if (conn->fd == -1) return C_ERR;
+    return anetDisableTcpNoDelay(NULL, conn->fd);
+}
+
+int connKeepAlive(connection *conn, int interval) {
+    if (conn->fd == -1) return C_ERR;
+    return anetKeepAlive(NULL, conn->fd, interval);
+}
+
+int connSendTimeout(connection *conn, long long ms) {
+    return anetSendTimeout(NULL, conn->fd, ms);
+}
+
+int connRecvTimeout(connection *conn, long long ms) {
+    return anetRecvTimeout(NULL, conn->fd, ms);
+}
+
+int connGetState(connection *conn) {
+    return conn->state;
+}
+
+/* Return a text that describes the connection, suitable for inclusion
+ * in CLIENT LIST and similar outputs.
+ *
+ * For sockets, we always return "fd=<fdnum>" to maintain compatibility.
+ */
+const char *connGetInfo(connection *conn, char *buf, size_t buf_len) {
+    snprintf(buf, buf_len-1, "fd=%i", conn == NULL ? -1 : conn->fd);
+    return buf;
+}
+