http.c

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/*
 * Copyright (C) 2007 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., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

FILE_LICENCE ( GPL2_OR_LATER );

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

#include <stdint.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <strings.h>
#include <byteswap.h>
#include <errno.h>
#include <assert.h>
#include <gpxe/uri.h>
#include <gpxe/refcnt.h>
#include <gpxe/iobuf.h>
#include <gpxe/xfer.h>
#include <gpxe/open.h>
#include <gpxe/socket.h>
#include <gpxe/tcpip.h>
#include <gpxe/process.h>
#include <gpxe/linebuf.h>
#include <gpxe/features.h>
#include <gpxe/base64.h>
#include <gpxe/http.h>

FEATURE ( FEATURE_PROTOCOL, "HTTP", DHCP_EB_FEATURE_HTTP, 1 );

/** HTTP receive state */
enum http_rx_state {
        HTTP_RX_RESPONSE = 0,
        HTTP_RX_HEADER,
        HTTP_RX_DATA,
        HTTP_RX_DEAD,
};

/**
 * An HTTP request
 *
 */
struct http_request {
        /** Reference count */
        struct refcnt refcnt;
        /** Data transfer interface */
        struct xfer_interface xfer;

        /** URI being fetched */
        struct uri *uri;
        /** Transport layer interface */
        struct xfer_interface socket;

        /** TX process */
        struct process process;

        /** HTTP response code */
        unsigned int response;
        /** HTTP Content-Length */
        size_t content_length;
        /** Received length */
        size_t rx_len;
        /** RX state */
        enum http_rx_state rx_state;
        /** Line buffer for received header lines */
        struct line_buffer linebuf;
};

/**
 * Free HTTP request
 *
 * @v refcnt            Reference counter
 */
static void http_free ( struct refcnt *refcnt ) {
        struct http_request *http =
                container_of ( refcnt, struct http_request, refcnt );

        uri_put ( http->uri );
        empty_line_buffer ( &http->linebuf );
        free ( http );
};

/**
 * Mark HTTP request as complete
 *
 * @v http              HTTP request
 * @v rc                Return status code
 */
static void http_done ( struct http_request *http, int rc ) {

        /* Prevent further processing of any current packet */
        http->rx_state = HTTP_RX_DEAD;

        /* If we had a Content-Length, and the received content length
         * isn't correct, flag an error
         */
        if ( http->content_length &&
             ( http->content_length != http->rx_len ) ) {
                DBGC ( http, "HTTP %p incorrect length %zd, should be %zd\n",
                       http, http->rx_len, http->content_length );
                rc = -EIO;
        }

        /* Remove process */
        process_del ( &http->process );

        /* Close all data transfer interfaces */
        xfer_nullify ( &http->socket );
        xfer_close ( &http->socket, rc );
        xfer_nullify ( &http->xfer );
        xfer_close ( &http->xfer, rc );
}

/**
 * Convert HTTP response code to return status code
 *
 * @v response          HTTP response code
 * @ret rc              Return status code
 */
static int http_response_to_rc ( unsigned int response ) {
        switch ( response ) {
        case 200:
        case 301:
        case 302:
                return 0;
        case 404:
                return -ENOENT;
        case 403:
                return -EPERM;
        case 401:
                return -EACCES;
        default:
                return -EIO;
        }
}

/**
 * Handle HTTP response
 *
 * @v http              HTTP request
 * @v response          HTTP response
 * @ret rc              Return status code
 */
static int http_rx_response ( struct http_request *http, char *response ) {
        char *spc;
        int rc;

        DBGC ( http, "HTTP %p response \"%s\"\n", http, response );

        /* Check response starts with "HTTP/" */
        if ( strncmp ( response, "HTTP/", 5 ) != 0 )
                return -EIO;

        /* Locate and check response code */
        spc = strchr ( response, ' ' );
        if ( ! spc )
                return -EIO;
        http->response = strtoul ( spc, NULL, 10 );
        if ( ( rc = http_response_to_rc ( http->response ) ) != 0 )
                return rc;

        /* Move to received headers */
        http->rx_state = HTTP_RX_HEADER;
        return 0;
}

/**
 * Handle HTTP Location header
 *
 * @v http              HTTP request
 * @v value             HTTP header value
 * @ret rc              Return status code
 */
static int http_rx_location ( struct http_request *http, const char *value ) {
        int rc;

        /* Redirect to new location */
        DBGC ( http, "HTTP %p redirecting to %s\n", http, value );
        if ( ( rc = xfer_redirect ( &http->xfer, LOCATION_URI_STRING,
                                    value ) ) != 0 ) {
                DBGC ( http, "HTTP %p could not redirect: %s\n",
                       http, strerror ( rc ) );
                return rc;
        }

        return 0;
}

/**
 * Handle HTTP Content-Length header
 *
 * @v http              HTTP request
 * @v value             HTTP header value
 * @ret rc              Return status code
 */
static int http_rx_content_length ( struct http_request *http,
                                    const char *value ) {
        char *endp;

        http->content_length = strtoul ( value, &endp, 10 );
        if ( *endp != '\0' ) {
                DBGC ( http, "HTTP %p invalid Content-Length \"%s\"\n",
                       http, value );
                return -EIO;
        }

        /* Use seek() to notify recipient of filesize */
        xfer_seek ( &http->xfer, http->content_length, SEEK_SET );
        xfer_seek ( &http->xfer, 0, SEEK_SET );

        return 0;
}

/** An HTTP header handler */
struct http_header_handler {
        /** Name (e.g. "Content-Length") */
        const char *header;
        /** Handle received header
         *
         * @v http      HTTP request
         * @v value     HTTP header value
         * @ret rc      Return status code
         *
         * If an error is returned, the download will be aborted.
         */
        int ( * rx ) ( struct http_request *http, const char *value );
};

/** List of HTTP header handlers */
static struct http_header_handler http_header_handlers[] = {
        {
                .header = "Location",
                .rx = http_rx_location,
        },
        {
                .header = "Content-Length",
                .rx = http_rx_content_length,
        },
        { NULL, NULL }
};

/**
 * Handle HTTP header
 *
 * @v http              HTTP request
 * @v header            HTTP header
 * @ret rc              Return status code
 */
static int http_rx_header ( struct http_request *http, char *header ) {
        struct http_header_handler *handler;
        char *separator;
        char *value;
        int rc;

        /* An empty header line marks the transition to the data phase */
        if ( ! header[0] ) {
                DBGC ( http, "HTTP %p start of data\n", http );
                empty_line_buffer ( &http->linebuf );
                http->rx_state = HTTP_RX_DATA;
                return 0;
        }

        DBGC ( http, "HTTP %p header \"%s\"\n", http, header );

        /* Split header at the ": " */
        separator = strstr ( header, ": " );
        if ( ! separator ) {
                DBGC ( http, "HTTP %p malformed header\n", http );
                return -EIO;
        }
        *separator = '\0';
        value = ( separator + 2 );

        /* Hand off to header handler, if one exists */
        for ( handler = http_header_handlers ; handler->header ; handler++ ) {
                if ( strcasecmp ( header, handler->header ) == 0 ) {
                        if ( ( rc = handler->rx ( http, value ) ) != 0 )
                                return rc;
                        break;
                }
        }
        return 0;
}

/** An HTTP line-based data handler */
struct http_line_handler {
        /** Handle line
         *
         * @v http      HTTP request
         * @v line      Line to handle
         * @ret rc      Return status code
         */
        int ( * rx ) ( struct http_request *http, char *line );
};

/** List of HTTP line-based data handlers */
static struct http_line_handler http_line_handlers[] = {
        [HTTP_RX_RESPONSE]      = { .rx = http_rx_response },
        [HTTP_RX_HEADER]        = { .rx = http_rx_header },
};

/**
 * Handle new data arriving via HTTP connection in the data phase
 *
 * @v http              HTTP request
 * @v iobuf             I/O buffer
 * @ret rc              Return status code
 */
static int http_rx_data ( struct http_request *http,
                          struct io_buffer *iobuf ) {
        int rc;

        /* Update received length */
        http->rx_len += iob_len ( iobuf );

        /* Hand off data buffer */
        if ( ( rc = xfer_deliver_iob ( &http->xfer, iobuf ) ) != 0 )
                return rc;

        /* If we have reached the content-length, stop now */
        if ( http->content_length &&
             ( http->rx_len >= http->content_length ) ) {
                http_done ( http, 0 );
        }

        return 0;
}

/**
 * Handle new data arriving via HTTP connection
 *
 * @v socket            Transport layer interface
 * @v iobuf             I/O buffer
 * @v meta              Data transfer metadata
 * @ret rc              Return status code
 */
static int http_socket_deliver_iob ( struct xfer_interface *socket,
                                     struct io_buffer *iobuf,
                                     struct xfer_metadata *meta __unused ) {
        struct http_request *http =
                container_of ( socket, struct http_request, socket );
        struct http_line_handler *lh;
        char *line;
        ssize_t len;
        int rc = 0;

        while ( iob_len ( iobuf ) ) {
                switch ( http->rx_state ) {
                case HTTP_RX_DEAD:
                        /* Do no further processing */
                        goto done;
                case HTTP_RX_DATA:
                        /* Once we're into the data phase, just fill
                         * the data buffer
                         */
                        rc = http_rx_data ( http, iob_disown ( iobuf ) );
                        goto done;
                case HTTP_RX_RESPONSE:
                case HTTP_RX_HEADER:
                        /* In the other phases, buffer and process a
                         * line at a time
                         */
                        len = line_buffer ( &http->linebuf, iobuf->data,
                                            iob_len ( iobuf ) );
                        if ( len < 0 ) {
                                rc = len;
                                DBGC ( http, "HTTP %p could not buffer line: "
                                       "%s\n", http, strerror ( rc ) );
                                goto done;
                        }
                        iob_pull ( iobuf, len );
                        line = buffered_line ( &http->linebuf );
                        if ( line ) {
                                lh = &http_line_handlers[http->rx_state];
                                if ( ( rc = lh->rx ( http, line ) ) != 0 )
                                        goto done;
                        }
                        break;
                default:
                        assert ( 0 );
                        break;
                }
        }

 done:
        if ( rc )
                http_done ( http, rc );
        free_iob ( iobuf );
        return rc;
}

/**
 * HTTP process
 *
 * @v process           Process
 */
static void http_step ( struct process *process ) {
        struct http_request *http =
                container_of ( process, struct http_request, process );
        const char *host = http->uri->host;
        const char *user = http->uri->user;
        const char *password =
                ( http->uri->password ? http->uri->password : "" );
        size_t user_pw_len = ( user ? ( strlen ( user ) + 1 /* ":" */ +
                                        strlen ( password ) ) : 0 );
        size_t user_pw_base64_len = base64_encoded_len ( user_pw_len );
        char user_pw[ user_pw_len + 1 /* NUL */ ];
        char user_pw_base64[ user_pw_base64_len + 1 /* NUL */ ];
        int rc;
        int request_len = unparse_uri ( NULL, 0, http->uri,
                                        URI_PATH_BIT | URI_QUERY_BIT );

        if ( xfer_window ( &http->socket ) ) {
                char request[request_len + 1];

                /* Construct path?query request */
                unparse_uri ( request, sizeof ( request ), http->uri,
                              URI_PATH_BIT | URI_QUERY_BIT );

                /* We want to execute only once */
                process_del ( &http->process );

                /* Construct authorisation, if applicable */
                if ( user ) {
                        /* Make "user:password" string from decoded fields */
                        snprintf ( user_pw, sizeof ( user_pw ), "%s:%s",
                                   user, password );

                        /* Base64-encode the "user:password" string */
                        base64_encode ( user_pw, user_pw_base64 );
                }

                /* Send GET request */
                if ( ( rc = xfer_printf ( &http->socket,
                                          "GET %s%s HTTP/1.0\r\n"
                                          "User-Agent: gPXE/" VERSION "\r\n"
                                          "%s%s%s"
                                          "Host: %s\r\n"
                                          "\r\n",
                                          http->uri->path ? "" : "/",
                                          request,
                                          ( user ?
                                            "Authorization: Basic " : "" ),
                                          ( user ? user_pw_base64 : "" ),
                                          ( user ? "\r\n" : "" ),
                                          host ) ) != 0 ) {
                        http_done ( http, rc );
                }
        }
}

/**
 * HTTP connection closed by network stack
 *
 * @v socket            Transport layer interface
 * @v rc                Reason for close
 */
static void http_socket_close ( struct xfer_interface *socket, int rc ) {
        struct http_request *http =
                container_of ( socket, struct http_request, socket );

        DBGC ( http, "HTTP %p socket closed: %s\n",
               http, strerror ( rc ) );
        
        http_done ( http, rc );
}

/** HTTP socket operations */
static struct xfer_interface_operations http_socket_operations = {
        .close          = http_socket_close,
        .vredirect      = xfer_vreopen,
        .window         = unlimited_xfer_window,
        .alloc_iob      = default_xfer_alloc_iob,
        .deliver_iob    = http_socket_deliver_iob,
        .deliver_raw    = xfer_deliver_as_iob,
};

/**
 * Close HTTP data transfer interface
 *
 * @v xfer              Data transfer interface
 * @v rc                Reason for close
 */
static void http_xfer_close ( struct xfer_interface *xfer, int rc ) {
        struct http_request *http =
                container_of ( xfer, struct http_request, xfer );

        DBGC ( http, "HTTP %p interface closed: %s\n",
               http, strerror ( rc ) );

        http_done ( http, rc );
}

/** HTTP data transfer interface operations */
static struct xfer_interface_operations http_xfer_operations = {
        .close          = http_xfer_close,
        .vredirect      = ignore_xfer_vredirect,
        .window         = unlimited_xfer_window,
        .alloc_iob      = default_xfer_alloc_iob,
        .deliver_iob    = xfer_deliver_as_raw,
        .deliver_raw    = ignore_xfer_deliver_raw,
};

/**
 * Initiate an HTTP connection, with optional filter
 *
 * @v xfer              Data transfer interface
 * @v uri               Uniform Resource Identifier
 * @v default_port      Default port number
 * @v filter            Filter to apply to socket, or NULL
 * @ret rc              Return status code
 */
int http_open_filter ( struct xfer_interface *xfer, struct uri *uri,
                       unsigned int default_port,
                       int ( * filter ) ( struct xfer_interface *xfer,
                                          struct xfer_interface **next ) ) {
        struct http_request *http;
        struct sockaddr_tcpip server;
        struct xfer_interface *socket;
        int rc;

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

        /* Allocate and populate HTTP structure */
        http = zalloc ( sizeof ( *http ) );
        if ( ! http )
                return -ENOMEM;
        http->refcnt.free = http_free;
        xfer_init ( &http->xfer, &http_xfer_operations, &http->refcnt );
        http->uri = uri_get ( uri );
        xfer_init ( &http->socket, &http_socket_operations, &http->refcnt );
        process_init ( &http->process, http_step, &http->refcnt );

        /* Open socket */
        memset ( &server, 0, sizeof ( server ) );
        server.st_port = htons ( uri_port ( http->uri, default_port ) );
        socket = &http->socket;
        if ( filter ) {
                if ( ( rc = filter ( socket, &socket ) ) != 0 )
                        goto err;
        }
        if ( ( rc = xfer_open_named_socket ( socket, SOCK_STREAM,
                                             ( struct sockaddr * ) &server,
                                             uri->host, NULL ) ) != 0 )
                goto err;

        /* Attach to parent interface, mortalise self, and return */
        xfer_plug_plug ( &http->xfer, xfer );
        ref_put ( &http->refcnt );
        return 0;

 err:
        DBGC ( http, "HTTP %p could not create request: %s\n", 
               http, strerror ( rc ) );
        http_done ( http, rc );
        ref_put ( &http->refcnt );
        return rc;
}

/**
 * Initiate an HTTP connection
 *
 * @v xfer              Data transfer interface
 * @v uri               Uniform Resource Identifier
 * @ret rc              Return status code
 */
static int http_open ( struct xfer_interface *xfer, struct uri *uri ) {
        return http_open_filter ( xfer, uri, HTTP_PORT, NULL );
}

/** HTTP URI opener */
struct uri_opener http_uri_opener __uri_opener = {
        .scheme = "http",
        .open   = http_open,
};