mod_proxy.c

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/* Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "mod_proxy.h"

#define CORE_PRIVATE

#include "http_log.h"
#include "http_core.h"
#include "http_vhost.h"
#include "http_request.h"

/* Some WWW schemes and their default ports; this is basically /etc/services */
/* This will become global when the protocol abstraction comes */
static struct proxy_services defports[] =
{
    {"http", DEFAULT_HTTP_PORT},
    {"ftp", DEFAULT_FTP_PORT},
    {"https", DEFAULT_HTTPS_PORT},
    {"gopher", DEFAULT_GOPHER_PORT},
    {"nntp", DEFAULT_NNTP_PORT},
    {"wais", DEFAULT_WAIS_PORT},
    {"snews", DEFAULT_SNEWS_PORT},
    {"prospero", DEFAULT_PROSPERO_PORT},
    {NULL, -1}                  /* unknown port */
};

/*
 * A Web proxy module. Stages:
 *
 *  translate_name: set filename to proxy:<URL>
 *  type_checker:   set type to PROXY_MAGIC_TYPE if filename begins proxy:
 *  fix_ups:        convert the URL stored in the filename to the
 *                  canonical form.
 *  handler:        handle proxy requests
 */

/* -------------------------------------------------------------- */
/* Translate the URL into a 'filename' */

static int alias_match(const char *uri, const char *alias_fakename)
{
    const char *end_fakename = alias_fakename + strlen(alias_fakename);
    const char *aliasp = alias_fakename, *urip = uri;

    while (aliasp < end_fakename) {
        if (*aliasp == '/') {
            /*
             * any number of '/' in the alias matches any number in the
             * supplied URI, but there must be at least one...
             */
            if (*urip != '/')
                return 0;

            while (*aliasp == '/')
                ++aliasp;
            while (*urip == '/')
                ++urip;
        }
        else {
            /* Other characters are compared literally */
            if (*urip++ != *aliasp++)
                return 0;
        }
    }

    /* Check last alias path component matched all the way */

    if (aliasp[-1] != '/' && *urip != '\0' && *urip != '/')
        return 0;

    /*
     * Return number of characters from URI which matched (may be greater
     * than length of alias, since we may have matched doubled slashes)
     */

    return urip - uri;
}

/* Detect if an absoluteURI should be proxied or not.  Note that we
 * have to do this during this phase because later phases are
 * "short-circuiting"... i.e. translate_names will end when the first
 * module returns OK.  So for example, if the request is something like:
 *
 * GET http://othervhost/cgi-bin/printenv HTTP/1.0
 *
 * mod_alias will notice the /cgi-bin part and ScriptAlias it and
 * short-circuit the proxy... just because of the ordering in the
 * configuration file.
 */
static int proxy_detect(request_rec *r)
{
    void *sconf = r->server->module_config;
    proxy_server_conf *conf;

    conf = (proxy_server_conf *)ap_get_module_config(sconf, &proxy_module);

    if (conf->req && r->parsed_uri.scheme) {
        /* but it might be something vhosted */
        if (!(r->parsed_uri.hostname
              && !strcasecmp(r->parsed_uri.scheme, ap_http_method(r))
              && ap_matches_request_vhost(r, r->parsed_uri.hostname,
        r->parsed_uri.port_str ? r->parsed_uri.port : ap_default_port(r)))) {
            r->proxyreq = STD_PROXY;
            r->uri = r->unparsed_uri;
            r->filename = ap_pstrcat(r->pool, "proxy:", r->uri, NULL);
            r->handler = "proxy-server";
        }
    }
    /* We need special treatment for CONNECT proxying: it has no scheme part */
    else if (conf->req && r->method_number == M_CONNECT
             && r->parsed_uri.hostname
             && r->parsed_uri.port_str) {
        r->proxyreq = STD_PROXY;
        r->uri = r->unparsed_uri;
        r->filename = ap_pstrcat(r->pool, "proxy:", r->uri, NULL);
        r->handler = "proxy-server";
    }
    return DECLINED;
}

static int proxy_trans(request_rec *r)
{
    void *sconf = r->server->module_config;
    proxy_server_conf *conf =
    (proxy_server_conf *)ap_get_module_config(sconf, &proxy_module);
    int i, len;
    struct proxy_alias *ent = (struct proxy_alias *)conf->aliases->elts;

    if (r->proxyreq != NOT_PROXY) {
        /*
         * someone has already set up the proxy, it was possibly ourselves in
         * proxy_detect
         */
        return OK;
    }

    /*
     * XXX: since r->uri has been manipulated already we're not really
     * compliant with RFC1945 at this point.  But this probably isn't an
     * issue because this is a hybrid proxy/origin server.
     */

    for (i = 0; i < conf->aliases->nelts; i++) {
        len = alias_match(r->uri, ent[i].fake);

        if (len > 0) {
            r->filename = ap_pstrcat(r->pool, "proxy:", ent[i].real,
                                     r->uri + len, NULL);
            r->handler = "proxy-server";
            r->proxyreq = PROXY_PASS;
            return OK;
        }
    }
    return DECLINED;
}

/* -------------------------------------------------------------- */
/* Fixup the filename */

/*
 * Canonicalise the URL
 */
static int proxy_fixup(request_rec *r)
{
    char *url, *p;

    if (r->proxyreq == NOT_PROXY || strncmp(r->filename, "proxy:", 6) != 0)
        return DECLINED;

    url = &r->filename[6];

/* canonicalise each specific scheme */
    if (strncasecmp(url, "http:", 5) == 0)
        return ap_proxy_http_canon(r, url + 5, "http", DEFAULT_HTTP_PORT);
    else if (strncasecmp(url, "ftp:", 4) == 0)
        return ap_proxy_ftp_canon(r, url + 4);

    p = strchr(url, ':');
    if (p == NULL || p == url)
        return HTTP_BAD_REQUEST;

    return OK;                  /* otherwise; we've done the best we can */
}

static void proxy_init(server_rec *r, pool *p)
{
    ap_proxy_garbage_init(r, p);
}



/* Send a redirection if the request contains a hostname which is not */
/* fully qualified, i.e. doesn't have a domain name appended. Some proxy */
/* servers like Netscape's allow this and access hosts from the local */
/* domain in this case. I think it is better to redirect to a FQDN, since */
/* these will later be found in the bookmarks files. */
/* The "ProxyDomain" directive determines what domain will be appended */
static int proxy_needsdomain(request_rec *r, const char *url, const char *domain)
{
    char *nuri;
    const char *ref;

    /* We only want to worry about GETs */
    if (r->proxyreq == NOT_PROXY || r->method_number != M_GET || !r->parsed_uri.hostname)
        return DECLINED;

    /* If host does contain a dot already, or it is "localhost", decline */
    if (strchr(r->parsed_uri.hostname, '.') != NULL
        || strcasecmp(r->parsed_uri.hostname, "localhost") == 0)
        return DECLINED;        /* host name has a dot already */

    ref = ap_table_get(r->headers_in, "Referer");

    /* Reassemble the request, but insert the domain after the host name */
    /* Note that the domain name always starts with a dot */
    r->parsed_uri.hostname = ap_pstrcat(r->pool, r->parsed_uri.hostname,
                                        domain, NULL);
    nuri = ap_unparse_uri_components(r->pool,
                                     &r->parsed_uri,
                                     UNP_REVEALPASSWORD);

    ap_table_set(r->headers_out, "Location", nuri);
    ap_log_rerror(APLOG_MARK, APLOG_INFO | APLOG_NOERRNO, r,
                  "Domain missing: %s sent to %s%s%s", r->uri,
                  ap_unparse_uri_components(r->pool, &r->parsed_uri,
                                            UNP_OMITUSERINFO),
                  ref ? " from " : "", ref ? ref : "");

    return HTTP_MOVED_PERMANENTLY;
}

/* -------------------------------------------------------------- */
/* Invoke handler */

static int proxy_handler(request_rec *r)
{
    char *url, *scheme, *p;
    void *sconf = r->server->module_config;
    proxy_server_conf *conf =
    (proxy_server_conf *)ap_get_module_config(sconf, &proxy_module);
    array_header *proxies = conf->proxies;
    struct proxy_remote *ents = (struct proxy_remote *) proxies->elts;
    int i, rc;
    cache_req *cr;
    int direct_connect = 0;
    const char *maxfwd_str;

    if (r->proxyreq == NOT_PROXY || strncmp(r->filename, "proxy:", 6) != 0)
        return DECLINED;

    if (r->method_number == M_TRACE &&
        (maxfwd_str = ap_table_get(r->headers_in, "Max-Forwards")) != NULL) {
        long maxfwd = ap_strtol(maxfwd_str, NULL, 10);
        if (maxfwd < 1) {
            int access_status;
            r->proxyreq = NOT_PROXY;
            if ((access_status = ap_send_http_trace(r)))
                ap_die(access_status, r);
            else
                ap_finalize_request_protocol(r);
            return OK;
        }
        ap_table_setn(r->headers_in, "Max-Forwards",
                ap_psprintf(r->pool, "%ld", (maxfwd > 0) ? maxfwd - 1 : 0));
    }

    if ((rc = ap_setup_client_block(r, REQUEST_CHUNKED_ERROR)))
        return rc;

    if (r->method_number == M_TRACE) {
        core_server_config *coreconf = (core_server_config *)
             ap_get_module_config(r->server->module_config, &core_module);

        if (coreconf->trace_enable == AP_TRACE_DISABLE)
        {
            /* Allow "error-notes" string to be printed by ap_send_error_response()
             * Note; this goes nowhere, canned error response need an overhaul.
             */
            ap_table_setn(r->notes, "error-notes",
                           "TRACE forbidden by server configuration");
            ap_table_setn(r->notes, "verbose-error-to", "*");
            ap_log_rerror(APLOG_MARK, APLOG_ERR|APLOG_NOERRNO, r,
                          "proxy: TRACE forbidden by server configuration");
            return HTTP_FORBIDDEN;
        }

        if (coreconf->trace_enable != AP_TRACE_EXTENDED 
            && (r->read_length || r->read_chunked || r->remaining))
        {
            /* Allow "error-notes" string to be printed by ap_send_error_response()
             * Note; this goes nowhere, canned error response need an overhaul.
             */
            ap_table_setn(r->notes, "error-notes",
                           "TRACE with request body is not allowed");
            ap_table_setn(r->notes, "verbose-error-to", "*");
            ap_log_rerror(APLOG_MARK, APLOG_ERR|APLOG_NOERRNO, r,
                          "proxy: TRACE with request body is not allowed");
            return HTTP_REQUEST_ENTITY_TOO_LARGE;
        }
    }

    url = r->filename + 6;
    p = strchr(url, ':');
    if (p == NULL)
        return HTTP_BAD_REQUEST;

    /* Try serve the request from the cache. If we succeed, we leave. */
    rc = ap_proxy_cache_check(r, url, &conf->cache, &cr);
    if (rc != DECLINED)
        return rc;

    /* If the host doesn't have a domain name, add one and redirect. */
    if (conf->domain != NULL) {
        rc = proxy_needsdomain(r, url, conf->domain);
        if (ap_is_HTTP_REDIRECT(rc))
            return HTTP_MOVED_PERMANENTLY;