httpbasic.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
 *
 * Hyper Text Transfer Protocol (HTTP) Basic authentication
 *
 */

#include <stdio.h>
#include <errno.h>
#include <ipxe/uri.h>
#include <ipxe/base64.h>
#include <ipxe/http.h>

/* Disambiguate the various error causes */
#define EACCES_USERNAME __einfo_error ( EINFO_EACCES_USERNAME )
#define EINFO_EACCES_USERNAME                                           \
        __einfo_uniqify ( EINFO_EACCES, 0x01,                           \
                          "No username available for Basic authentication" )

/**
 * Parse HTTP "WWW-Authenticate" header for Basic authentication
 *
 * @v http              HTTP transaction
 * @v line              Remaining header line
 * @ret rc              Return status code
 */
static int http_parse_basic_auth ( struct http_transaction *http,
                                   char *line __unused ) {

        /* Allow HTTP request to be retried if the request had not
         * already tried authentication.
         */
        if ( ! http->request.auth.auth )
                http->response.flags |= HTTP_RESPONSE_RETRY;

        return 0;
}

/**
 * Perform HTTP Basic authentication
 *
 * @v http              HTTP transaction
 * @ret rc              Return status code
 */
static int http_basic_authenticate ( struct http_transaction *http ) {
        struct http_request_auth_basic *req = &http->request.auth.basic;

        /* Record username and password */
        if ( ! http->uri->user ) {
                DBGC ( http, "HTTP %p has no username for Basic "
                       "authentication\n", http );
                return -EACCES_USERNAME;
        }
        req->username = http->uri->user;
        req->password = ( http->uri->password ? http->uri->password : "" );

        return 0;
}

/**
 * Construct HTTP "Authorization" header for Basic authentication
 *
 * @v http              HTTP transaction
 * @v buf               Buffer
 * @v len               Length of buffer
 * @ret len             Length of header value, or negative error
 */
static int http_format_basic_auth ( struct http_transaction *http,
                                    char *buf, size_t len ) {
        struct http_request_auth_basic *req = &http->request.auth.basic;
        size_t user_pw_len = ( strlen ( req->username ) + 1 /* ":" */ +
                               strlen ( req->password ) );
        char user_pw[ user_pw_len + 1 /* NUL */ ];

        /* Sanity checks */
        assert ( req->username != NULL );
        assert ( req->password != NULL );

        /* Construct "user:password" string */
        snprintf ( user_pw, sizeof ( user_pw ), "%s:%s",
                   req->username, req->password );

        /* Construct response */
        return base64_encode ( user_pw, user_pw_len, buf, len );
}

/** HTTP Basic authentication scheme */
struct http_authentication http_basic_auth __http_authentication = {
        .name = "Basic",
        .parse = http_parse_basic_auth,
        .authenticate = http_basic_authenticate,
        .format = http_format_basic_auth,
};

/* Drag in HTTP authentication support */
REQUIRING_SYMBOL ( http_basic_auth );
REQUIRE_OBJECT ( httpauth );