mod_setenvif.c

Apache HTTP Server 是一个功能强大的灵活的与HTTP/1.1相兼容的web服务器.这里给出的是Apache HTTP服务器的源码。

/* Copyright 1999-2005 The Apache Software Foundation or its licensors, as
 * applicable.
 *
 * Licensed 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.
 */

/*
 * mod_setenvif.c
 * Set environment variables based on matching request headers or
 * attributes against regex strings
 * 
 * Paul Sutton <[e-mail]> 27 Oct 1996
 * Based on mod_browser by Alexei Kosut <[e-mail]>
 */

/*
 * Used to set environment variables based on the incoming request headers,
 * or some selected other attributes of the request (e.g., the remote host
 * name).
 *
 * Usage:
 *
 *   SetEnvIf name regex var ...
 *
 * where name is either a HTTP request header name, or one of the
 * special values (see below). 'name' may be a regex when it is used
 * to specify an HTTP request header name. The 'value' of the header 
 & (or the value of the special value from below) are compared against
 * the regex argument. If this is a simple string, a simple sub-string
 * match is performed. Otherwise, a request expression match is
 * done. If the value matches the string or regular expression, the
 * environment variables listed as var ... are set. Each var can 
 * be in one of three formats: var, which sets the named variable
 * (the value value "1"); var=value, which sets the variable to
 * the given value; or !var, which unsets the variable is it has
 * been previously set.
 *
 * Normally the strings are compared with regard to case. To ignore
 * case, use the directive SetEnvIfNoCase instead.
 *
 * Special values for 'name' are:
 *
 *   server_addr      	IP address of interface on which request arrived
 *			(analogous to SERVER_ADDR set in ap_add_common_vars())
 *   remote_host        Remote host name (if available)
 *   remote_addr        Remote IP address
 *   request_method     Request method (GET, POST, etc)
 *   request_uri        Requested URI
 *
 * Examples:
 *
 * To set the enviroment variable LOCALHOST if the client is the local
 * machine:
 *
 *    SetEnvIf remote_addr 127.0.0.1 LOCALHOST
 *
 * To set LOCAL if the client is the local host, or within our company's
 * domain (192.168.10):
 *
 *    SetEnvIf remote_addr 192.168.10. LOCAL
 *    SetEnvIf remote_addr 127.0.0.1   LOCALHOST
 *
 * This could be written as:
 *
 *    SetEnvIf remote_addr (127.0.0.1|192.168.10.) LOCAL
 *
 * To set HAVE_TS if the client request contains any header beginning
 * with "TS" with a value beginning with a lower case alphabet:
 *
 *    SetEnvIf ^TS* ^[a-z].* HAVE_TS
 */

#include "apr.h"
#include "apr_strings.h"
#include "apr_strmatch.h"

#define APR_WANT_STRFUNC
#include "apr_want.h"

#include "ap_config.h"
#include "httpd.h"
#include "http_config.h"
#include "http_core.h"
#include "http_log.h"
#include "http_protocol.h"


enum special {
    SPECIAL_NOT,
    SPECIAL_REMOTE_ADDR,
    SPECIAL_REMOTE_HOST,
    SPECIAL_REQUEST_URI,
    SPECIAL_REQUEST_METHOD,
    SPECIAL_REQUEST_PROTOCOL,
    SPECIAL_SERVER_ADDR
};
typedef struct {
    char *name;                 /* header name */
    regex_t *pnamereg;          /* compiled header name regex */
    char *regex;                /* regex to match against */
    regex_t *preg;              /* compiled regex */
    const apr_strmatch_pattern *pattern; /* non-regex pattern to match */
    apr_table_t *features;      /* env vars to set (or unset) */
    enum special special_type;  /* is it a "special" header ? */
    int icase;                  /* ignoring case? */
} sei_entry;

typedef struct {
    apr_array_header_t *conditionals;
} sei_cfg_rec;

module AP_MODULE_DECLARE_DATA setenvif_module;

/*
 * These routines, the create- and merge-config functions, are called
 * for both the server-wide and the per-directory contexts.  This is
 * because the different definitions are used at different times; the
 * server-wide ones are used in the post-read-request phase, and the
 * per-directory ones are used during the header-parse phase (after
 * the URI has been mapped to a file and we have anything from the
 * .htaccess file and <Directory> and <Files> containers).
 */
static void *create_setenvif_config(apr_pool_t *p)
{
    sei_cfg_rec *new = (sei_cfg_rec *) apr_palloc(p, sizeof(sei_cfg_rec));

    new->conditionals = apr_array_make(p, 20, sizeof(sei_entry));
    return (void *) new;
}

static void *create_setenvif_config_svr(apr_pool_t *p, server_rec *dummy)
{
    return create_setenvif_config(p);
}

static void *create_setenvif_config_dir(apr_pool_t *p, char *dummy)
{
    return create_setenvif_config(p);
}

static void *merge_setenvif_config(apr_pool_t *p, void *basev, void *overridesv)
{
    sei_cfg_rec *a = apr_pcalloc(p, sizeof(sei_cfg_rec));
    sei_cfg_rec *base = basev, *overrides = overridesv;

    a->conditionals = apr_array_append(p, base->conditionals,
                                       overrides->conditionals);
    return a;
}

/*
 * any non-NULL magic constant will do... used to indicate if REG_ICASE should
 * be used
 */
#define ICASE_MAGIC	((void *)(&setenvif_module))
#define SEI_MAGIC_HEIRLOOM "setenvif-phase-flag"

static int is_header_regex(apr_pool_t *p, const char* name) 
{
    /* If a Header name contains characters other than:
     *    -,_,[A-Z\, [a-z] and [0-9].
     * assume the header name is a regular expression.
     */
    regex_t *preg = ap_pregcomp(p, "^[-A-Za-z0-9_]*$",
                                (REG_EXTENDED | REG_NOSUB ));
    ap_assert(preg != NULL);

    if (ap_regexec(preg, name, 0, NULL, 0)) {
        return 1;
    }

    return 0;
}

/* If the input string does not take advantage of regular
 * expression metacharacters, return a pointer to an equivalent
 * string that can be searched using apr_strmatch().  (The
 * returned string will often be the input string.  But if
 * the input string contains escaped characters, the returned
 * string will be a copy with the escapes removed.)
 */
static const char *non_regex_pattern(apr_pool_t *p, const char *s)
{
    const char *src = s;
    int escapes_found = 0;
    int in_escape = 0;

    while (*src) {
        switch (*src) {
        case '^':
        case '.':
        case '$':
        case '|':
        case '(':
        case ')':
        case '[':
        case ']':
        case '*':
        case '+':
        case '?':
        case '{':
        case '}':
            if (!in_escape) {
                return NULL;
            }
            in_escape = 0;
            break;
        case '\\':
            if (!in_escape) {
                in_escape = 1;
                escapes_found = 1;
            }
            else {
                in_escape = 0;
            }
            break;
        default:
            if (in_escape) {
                return NULL;
            }
            break;
        }
        src++;
    }
    if (!escapes_found) {
        return s;
    }
    else {
        char *unescaped = (char *)apr_palloc(p, src - s + 1);
        char *dst = unescaped;
        src = s;
        do {
            if (*src == '\\') {
                src++;
            }
        } while ((*dst++ = *src++));
        return unescaped;
    }
}

static const char *add_setenvif_core(cmd_parms *cmd, void *mconfig,
				     char *fname, const char *args)
{
    char *regex;
    const char *simple_pattern;
    const char *feature;
    sei_cfg_rec *sconf;
    sei_entry *new;
    sei_entry *entries;
    char *var;
    int i;
    int beenhere = 0;
    int icase;

    /*
     * Determine from our context into which record to put the entry.
     * cmd->path == NULL means we're in server-wide context; otherwise,
     * we're dealing with a per-directory setting.
     */
    sconf = (cmd->path != NULL)
      ? (sei_cfg_rec *) mconfig
      : (sei_cfg_rec *) ap_get_module_config(cmd->server->module_config,
					       &setenvif_module);
    entries = (sei_entry *) sconf->conditionals->elts;
    /* get regex */
    regex = ap_getword_conf(cmd->pool, &args);
    if (!*regex) {
        return apr_pstrcat(cmd->pool, "Missing regular expression for ",
                           cmd->cmd->name, NULL);
    }

    /*
     * If we've already got a sei_entry with the same name we want to
     * just copy the name pointer... so that later on we can compare
     * two header names just by comparing the pointers.
     */
    for (i = 0; i < sconf->conditionals->nelts; ++i) {
        new = &entries[i];
        if (!strcasecmp(new->name, fname)) {
            fname = new->name;
            break;
        }
    }