httpconn.c

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/*
 * Copyright (C) 2015 Michael Brown <mbrown@fensystems.co.uk>.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 *
 * You can also choose to distribute this program under the terms of
 * the Unmodified Binary Distribution Licence (as given in the file
 * COPYING.UBDL), provided that you have satisfied its requirements.
 */

FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
FILE_SECBOOT ( PERMITTED );

/**
 * @file
 *
 * Hyper Text Transfer Protocol (HTTP) connection management
 *
 */

#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include <errno.h>
#include <byteswap.h>
#include <ipxe/tcpip.h>
#include <ipxe/uri.h>
#include <ipxe/timer.h>
#include <ipxe/xfer.h>
#include <ipxe/open.h>
#include <ipxe/pool.h>
#include <ipxe/http.h>

/** HTTP pooled connection expiry time */
#define HTTP_CONN_EXPIRY ( 10 * TICKS_PER_SEC )

/** HTTP connection pool */
static LIST_HEAD ( http_connection_pool );

/**
 * Identify HTTP scheme
 *
 * @v uri               URI
 * @ret scheme          HTTP scheme, or NULL
 */
static struct http_scheme * http_scheme ( struct uri *uri ) {
        struct http_scheme *scheme;

        /* Sanity check */
        if ( ! uri->scheme )
                return NULL;

        /* Identify scheme */
        for_each_table_entry ( scheme, HTTP_SCHEMES ) {
                if ( strcasecmp ( uri->scheme, scheme->name ) == 0 )
                        return scheme;
        }

        return NULL;
}

/**
 * Free HTTP connection
 *
 * @v refcnt            Reference count
 */
static void http_conn_free ( struct refcnt *refcnt ) {
        struct http_connection *conn =
                container_of ( refcnt, struct http_connection, refcnt );

        /* Free connection */
        uri_put ( conn->uri );
        free ( conn );
}

/**
 * Close HTTP connection
 *
 * @v conn              HTTP connection
 * @v rc                Reason for close
 */
static void http_conn_close ( struct http_connection *conn, int rc ) {

        /* Remove from connection pool, if applicable */
        pool_del ( &conn->pool );

        /* Shut down interfaces */
        intf_shutdown ( &conn->socket, rc );
        intf_shutdown ( &conn->xfer, rc );
        if ( rc == 0 ) {
                DBGC2 ( conn, "HTTPCONN %p closed %s://%s\n",
                        conn, conn->scheme->name, conn->uri->host );
        } else {
                DBGC ( conn, "HTTPCONN %p closed %s://%s: %s\n",
                       conn, conn->scheme->name, conn->uri->host,
                       strerror ( rc ) );
        }
}

/**
 * Disconnect idle HTTP connection
 *
 * @v pool              Pooled connection
 */
static void http_conn_expired ( struct pooled_connection *pool ) {
        struct http_connection *conn =
                container_of ( pool, struct http_connection, pool );

        /* Close connection */
        http_conn_close ( conn, 0 /* Not an error to close idle connection */ );
}

/**
 * Receive data from transport layer interface
 *
 * @v http              HTTP connection
 * @v iobuf             I/O buffer
 * @v meta              Transfer metadata
 * @ret rc              Return status code
 */
static int http_conn_socket_deliver ( struct http_connection *conn,
                                      struct io_buffer *iobuf,
                                      struct xfer_metadata *meta ) {

        /* Mark connection as alive */
        pool_alive ( &conn->pool );

        /* Pass on to data transfer interface */
        return xfer_deliver ( &conn->xfer, iobuf, meta );
}

/**
 * Close HTTP connection transport layer interface
 *
 * @v http              HTTP connection
 * @v rc                Reason for close
 */
static void http_conn_socket_close ( struct http_connection *conn, int rc ) {

        /* If we are reopenable (i.e. we are a recycled connection
         * from the connection pool, and we have received no data from
         * the underlying socket since we were pooled), then suggest
         * that the client should reopen the connection.
         */
        if ( pool_is_reopenable ( &conn->pool ) )
                pool_reopen ( &conn->xfer );

        /* Close the connection */
        http_conn_close ( conn, rc );
}

/**
 * Recycle this connection after closing
 *
 * @v http              HTTP connection
 */
static void http_conn_xfer_recycle ( struct http_connection *conn ) {

        /* Mark connection as recyclable */
        pool_recyclable ( &conn->pool );
        DBGC2 ( conn, "HTTPCONN %p keepalive enabled\n", conn );
}

/**
 * Close HTTP connection data transfer interface
 *
 * @v conn              HTTP connection
 * @v rc                Reason for close
 */
static void http_conn_xfer_close ( struct http_connection *conn, int rc ) {

        /* Add to the connection pool if keepalive is enabled and no
         * error occurred.
         */
        if ( ( rc == 0 ) && pool_is_recyclable ( &conn->pool ) ) {
                intf_restart ( &conn->xfer, rc );
                pool_add ( &conn->pool, &http_connection_pool,
                           HTTP_CONN_EXPIRY );
                DBGC2 ( conn, "HTTPCONN %p pooled %s://%s\n",
                        conn, conn->scheme->name, conn->uri->host );
                return;
        }

        /* Otherwise, close the connection */
        http_conn_close ( conn, rc );
}

/** HTTP connection socket interface operations */
static struct interface_operation http_conn_socket_operations[] = {
        INTF_OP ( xfer_deliver, struct http_connection *,
                  http_conn_socket_deliver ),
        INTF_OP ( intf_close, struct http_connection *,
                  http_conn_socket_close ),
};

/** HTTP connection socket interface descriptor */
static struct interface_descriptor http_conn_socket_desc =
        INTF_DESC_PASSTHRU ( struct http_connection, socket,
                             http_conn_socket_operations, xfer );

/** HTTP connection data transfer interface operations */
static struct interface_operation http_conn_xfer_operations[] = {
        INTF_OP ( pool_recycle, struct http_connection *,
                  http_conn_xfer_recycle ),
        INTF_OP ( intf_close, struct http_connection *,
                  http_conn_xfer_close ),
};

/** HTTP connection data transfer interface descriptor */
static struct interface_descriptor http_conn_xfer_desc =
        INTF_DESC_PASSTHRU ( struct http_connection, xfer,
                             http_conn_xfer_operations, socket );

/**
 * Connect to an HTTP server
 *
 * @v xfer              Data transfer interface
 * @v uri               Connection URI
 * @ret rc              Return status code
 *
 * HTTP connections are pooled.  The caller should be prepared to
 * receive a pool_reopen() message.
 */
int http_connect ( struct interface *xfer, struct uri *uri ) {
        struct http_connection *conn;
        struct http_scheme *scheme;
        struct sockaddr_tcpip server;
        unsigned int port;
        int rc;

        /* Identify scheme */
        scheme = http_scheme ( uri );
        if ( ! scheme )
                return -ENOTSUP;

        /* Sanity check */
        if ( ! uri->host )
                return -EINVAL;

        /* Identify port */
        port = uri_port ( uri, scheme->port );

        /* Look for a reusable connection in the pool.  Reuse the most
         * recent connection in order to accommodate authentication
         * schemes that break the stateless nature of HTTP and rely on
         * the same connection being reused for authentication
         * responses.
         */
        list_for_each_entry_reverse ( conn, &http_connection_pool, pool.list ) {

                /* Sanity checks */
                assert ( conn->uri != NULL );
                assert ( conn->uri->host != NULL );

                /* Reuse connection, if possible */
                if ( ( scheme == conn->scheme ) &&
                     ( strcmp ( uri->host, conn->uri->host ) == 0 ) &&
                     ( port == uri_port ( conn->uri, scheme->port ) ) ) {

                        /* Remove from connection pool, stop timer,
                         * attach to parent interface, and return.
                         */
                        pool_del ( &conn->pool );
                        intf_plug_plug ( &conn->xfer, xfer );
                        DBGC2 ( conn, "HTTPCONN %p reused %s://%s:%d\n", conn,
                                conn->scheme->name, conn->uri->host, port );
                        return 0;
                }
        }

        /* Allocate and initialise structure */
        conn = zalloc ( sizeof ( *conn ) );
        if ( ! conn ) {
                rc = -ENOMEM;
                goto err_alloc;
        }
        ref_init ( &conn->refcnt, http_conn_free );
        conn->uri = uri_get ( uri );
        conn->scheme = scheme;
        intf_init ( &conn->socket, &http_conn_socket_desc, &conn->refcnt );
        intf_init ( &conn->xfer, &http_conn_xfer_desc, &conn->refcnt );
        pool_init ( &conn->pool, http_conn_expired, &conn->refcnt );

        /* Open socket */
        memset ( &server, 0, sizeof ( server ) );
        server.st_port = htons ( port );
        if ( ( rc = xfer_open_named_socket ( &conn->socket, SOCK_STREAM,
                                             ( struct sockaddr * ) &server,
                                             uri->host, NULL ) ) != 0 )
                goto err_open;

        /* Add filter, if any */
        if ( scheme->filter && ( ( rc = scheme->filter ( conn ) ) != 0 ) )
                goto err_filter;

        /* Attach to parent interface, mortalise self, and return */
        intf_plug_plug ( &conn->xfer, xfer );
        ref_put ( &conn->refcnt );

        DBGC2 ( conn, "HTTPCONN %p created %s://%s:%d\n", conn,
                conn->scheme->name, conn->uri->host, port );
        return 0;

 err_filter:
 err_open:
        DBGC2 ( conn, "HTTPCONN %p could not create %s://%s:%d: %s\n", conn,
                conn->scheme->name, conn->uri->host, port, strerror ( rc ) );
        http_conn_close ( conn, rc );
        ref_put ( &conn->refcnt );
 err_alloc:
        return rc;
}