mod_charset_lite.c

Apache官方在今天放出产品系列2.2的最新版本2.2.11的源码包 最流行的HTTP服务器软件之一

/* 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.
 */

/*
 * simple hokey charset recoding configuration module
 *
 * See mod_ebcdic and mod_charset for more thought-out examples.  This
 * one is just so Jeff can learn how a module works and experiment with
 * basic character set recoding configuration.
 *
 * !!!This is an extremely cheap ripoff of mod_charset.c from Russian Apache!!!
 */

#include "httpd.h"
#include "http_config.h"
#define CORE_PRIVATE
#include "http_core.h"
#include "http_log.h"
#include "http_main.h"
#include "http_protocol.h"
#include "http_request.h"
#include "util_charset.h"
#include "apr_buckets.h"
#include "util_filter.h"
#include "apr_strings.h"
#include "apr_lib.h"
#include "apr_xlate.h"
#define APR_WANT_STRFUNC
#include "apr_want.h"

#define OUTPUT_XLATE_BUF_SIZE (16*1024) /* size of translation buffer used on output */
#define INPUT_XLATE_BUF_SIZE  (8*1024)  /* size of translation buffer used on input */

#define XLATE_MIN_BUFF_LEFT 128  /* flush once there is no more than this much
                                  * space left in the translation buffer
                                  */

#define FATTEST_CHAR  8          /* we don't handle chars wider than this that straddle
                                  * two buckets
                                  */

/* extended error status codes; this is used in addition to an apr_status_t to
 * track errors in the translation filter
 */
typedef enum {
    EES_INIT = 0,   /* no error info yet; value must be 0 for easy init */
    EES_LIMIT,      /* built-in restriction encountered */
    EES_INCOMPLETE_CHAR, /* incomplete multi-byte char at end of content */
    EES_BUCKET_READ,
    EES_DOWNSTREAM, /* something bad happened in a filter below xlate */
    EES_BAD_INPUT   /* input data invalid */
} ees_t;

/* registered name of the output translation filter */
#define XLATEOUT_FILTER_NAME "XLATEOUT"
/* registered name of input translation filter */
#define XLATEIN_FILTER_NAME  "XLATEIN"

typedef struct charset_dir_t {
    /** debug level; -1 means uninitialized, 0 means no debug */
    int debug;
    const char *charset_source; /* source encoding */
    const char *charset_default; /* how to ship on wire */
    /** module does ap_add_*_filter()? */
    enum {IA_INIT, IA_IMPADD, IA_NOIMPADD} implicit_add;
    /** treat all mimetypes as text? */
    enum {FX_INIT, FX_FORCE, FX_NOFORCE} force_xlate;
} charset_dir_t;

/* charset_filter_ctx_t is created for each filter instance; because the same
 * filter code is used for translating in both directions, we need this context
 * data to tell the filter which translation handle to use; it also can hold a
 * character which was split between buckets
 */
typedef struct charset_filter_ctx_t {
    apr_xlate_t *xlate;
    int is_sb;              /* single-byte translation? */
    charset_dir_t *dc;
    ees_t ees;              /* extended error status */
    apr_size_t saved;
    char buf[FATTEST_CHAR]; /* we want to be able to build a complete char here */
    int ran;                /* has filter instance run before? */
    int noop;               /* should we pass brigades through unchanged? */
    char *tmp;              /* buffer for input filtering */
    apr_bucket_brigade *bb; /* input buckets we couldn't finish translating */
    apr_bucket_brigade *tmpbb; /* used for passing downstream */
} charset_filter_ctx_t;

/* charset_req_t is available via r->request_config if any translation is
 * being performed
 */
typedef struct charset_req_t {
    charset_dir_t *dc;
    charset_filter_ctx_t *output_ctx, *input_ctx;
} charset_req_t;

/* debug level definitions */
#define DBGLVL_GORY           9 /* gory details */
#define DBGLVL_FLOW           4 /* enough messages to see what happens on
                                 * each request */
#define DBGLVL_PMC            2 /* messages about possible misconfiguration */

module AP_MODULE_DECLARE_DATA charset_lite_module;

static void *create_charset_dir_conf(apr_pool_t *p,char *dummy)
{
    charset_dir_t *dc = (charset_dir_t *)apr_pcalloc(p,sizeof(charset_dir_t));

    dc->debug = -1;
    return dc;
}

static void *merge_charset_dir_conf(apr_pool_t *p, void *basev, void *overridesv)
{
    charset_dir_t *a = (charset_dir_t *)apr_pcalloc (p, sizeof(charset_dir_t));
    charset_dir_t *base = (charset_dir_t *)basev,
        *over = (charset_dir_t *)overridesv;

    /* If it is defined in the current container, use it.  Otherwise, use the one
     * from the enclosing container.
     */

    a->debug =
        over->debug != -1 ? over->debug : base->debug;
    a->charset_default =
        over->charset_default ? over->charset_default : base->charset_default;
    a->charset_source =
        over->charset_source ? over->charset_source : base->charset_source;
    a->implicit_add =
        over->implicit_add != IA_INIT ? over->implicit_add : base->implicit_add;
    a->force_xlate=
        over->force_xlate != FX_INIT ? over->force_xlate : base->force_xlate;
    return a;
}

/* CharsetSourceEnc charset
 */
static const char *add_charset_source(cmd_parms *cmd, void *in_dc,
                                      const char *name)
{
    charset_dir_t *dc = in_dc;

    dc->charset_source = name;
    return NULL;
}

/* CharsetDefault charset
 */
static const char *add_charset_default(cmd_parms *cmd, void *in_dc,
                                       const char *name)
{
    charset_dir_t *dc = in_dc;

    dc->charset_default = name;
    return NULL;
}

/* CharsetOptions optionflag...
 */
static const char *add_charset_options(cmd_parms *cmd, void *in_dc,
                                       const char *flag)
{
    charset_dir_t *dc = in_dc;

    if (!strcasecmp(flag, "ImplicitAdd")) {
        dc->implicit_add = IA_IMPADD;
    }
    else if (!strcasecmp(flag, "NoImplicitAdd")) {
        dc->implicit_add = IA_NOIMPADD;
    }
    if (!strcasecmp(flag, "TranslateAllMimeTypes")) {
        dc->force_xlate = FX_FORCE;
    }
    else if (!strcasecmp(flag, "NoTranslateAllMimeTypes")) {
        dc->force_xlate = FX_NOFORCE;
    }
    else if (!strncasecmp(flag, "DebugLevel=", 11)) {
        dc->debug = atoi(flag + 11);
    }
    else {
        return apr_pstrcat(cmd->temp_pool,
                           "Invalid CharsetOptions option: ",
                           flag,
                           NULL);
    }

    return NULL;
}

/* find_code_page() is a fixup hook that checks if the module is
 * configured and the input or output potentially need to be translated.
 * If so, context is initialized for the filters.
 */
static int find_code_page(request_rec *r)
{
    charset_dir_t *dc = ap_get_module_config(r->per_dir_config,
                                             &charset_lite_module);
    charset_req_t *reqinfo;
    charset_filter_ctx_t *input_ctx, *output_ctx;
    apr_status_t rv;

    if (dc->debug >= DBGLVL_FLOW) {
        ap_log_rerror(APLOG_MARK,APLOG_DEBUG, 0, r,
                      "uri: %s file: %s method: %d "
                      "imt: %s flags: %s%s%s %s->%s",
                      r->uri,
                      r->filename ? r->filename : "(none)",
                      r->method_number,
                      r->content_type ? r->content_type : "(unknown)",
                      r->main     ? "S" : "",    /* S if subrequest */
                      r->prev     ? "R" : "",    /* R if redirect */
                      r->proxyreq ? "P" : "",    /* P if proxy */
                      dc->charset_source, dc->charset_default);
    }

    /* If we don't have a full directory configuration, bail out.
     */
    if (!dc->charset_source || !dc->charset_default) {
        if (dc->debug >= DBGLVL_PMC) {
            ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r,
                          "incomplete configuration: src %s, dst %s",
                          dc->charset_source ? dc->charset_source : "unspecified",
                          dc->charset_default ? dc->charset_default : "unspecified");
        }
        return DECLINED;
    }

    /* catch proxy requests */
    if (r->proxyreq) {
        return DECLINED;
    }

    /* mod_rewrite indicators */
    if (r->filename
        && (!strncmp(r->filename, "redirect:", 9)
            || !strncmp(r->filename, "gone:", 5)
            || !strncmp(r->filename, "passthrough:", 12)
            || !strncmp(r->filename, "forbidden:", 10))) {
        return DECLINED;
    }

    /* no translation when server and network charsets are set to the same value */
    if (!strcasecmp(dc->charset_source, dc->charset_default)) {
        return DECLINED;
    }

    /* Get storage for the request data and the output filter context.
     * We rarely need the input filter context, so allocate that separately.
     */
    reqinfo = (charset_req_t *)apr_pcalloc(r->pool,
                                           sizeof(charset_req_t) +
                                           sizeof(charset_filter_ctx_t));
    output_ctx = (charset_filter_ctx_t *)(reqinfo + 1);

    reqinfo->dc = dc;
    output_ctx->dc = dc;
    output_ctx->tmpbb = apr_brigade_create(r->pool, 
                                           r->connection->bucket_alloc);
    ap_set_module_config(r->request_config, &charset_lite_module, reqinfo);

    reqinfo->output_ctx = output_ctx;

    switch (r->method_number) {
    case M_PUT:
    case M_POST:
        /* Set up input translation.  Note: A request body can be included
         * with the OPTIONS method, but for now we don't set up translation
         * of it.
         */
        input_ctx = apr_pcalloc(r->pool, sizeof(charset_filter_ctx_t));
        input_ctx->bb = apr_brigade_create(r->pool,
                                           r->connection->bucket_alloc);
        input_ctx->tmp = apr_palloc(r->pool, INPUT_XLATE_BUF_SIZE);
        input_ctx->dc = dc;
        reqinfo->input_ctx = input_ctx;
        rv = apr_xlate_open(&input_ctx->xlate, dc->charset_source,
                            dc->charset_default, r->pool);
        if (rv != APR_SUCCESS) {
            ap_log_rerror(APLOG_MARK, APLOG_ERR, rv, r,
                          "can't open translation %s->%s",
                          dc->charset_default, dc->charset_source);
            return HTTP_INTERNAL_SERVER_ERROR;
        }
        if (apr_xlate_sb_get(input_ctx->xlate, &input_ctx->is_sb) != APR_SUCCESS) {
            input_ctx->is_sb = 0;
        }
    }

    return DECLINED;
}

static int configured_in_list(request_rec *r, const char *filter_name,
                              struct ap_filter_t *filter_list)
{
    struct ap_filter_t *filter = filter_list;

    while (filter) {
        if (!strcasecmp(filter_name, filter->frec->name)) {
            return 1;
        }
        filter = filter->next;
    }
    return 0;
}

static int configured_on_input(request_rec *r, const char *filter_name)
{
    return configured_in_list(r, filter_name, r->input_filters);
}

static int configured_on_output(request_rec *r, const char *filter_name)
{
    return configured_in_list(r, filter_name, r->output_filters);
}

/* xlate_insert_filter() is a filter hook which decides whether or not
 * to insert a translation filter for the current request.
 */
static void xlate_insert_filter(request_rec *r)
{
    /* Hey... don't be so quick to use reqinfo->dc here; reqinfo may be NULL */
    charset_req_t *reqinfo = ap_get_module_config(r->request_config,
                                                  &charset_lite_module);
    charset_dir_t *dc = ap_get_module_config(r->per_dir_config,
                                             &charset_lite_module);

    if (reqinfo) {
        if (reqinfo->output_ctx && !configured_on_output(r, XLATEOUT_FILTER_NAME)) {
            ap_add_output_filter(XLATEOUT_FILTER_NAME, reqinfo->output_ctx, r,
                                 r->connection);
        }
        else if (dc->debug >= DBGLVL_FLOW) {
            ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r,
                          "xlate output filter not added implicitly because %s",
                          !reqinfo->output_ctx ?
                          "no output configuration available" :
                          "another module added the filter");
        }

        if (reqinfo->input_ctx && !configured_on_input(r, XLATEIN_FILTER_NAME)) {
            ap_add_input_filter(XLATEIN_FILTER_NAME, reqinfo->input_ctx, r,
                                r->connection);
        }
        else if (dc->debug >= DBGLVL_FLOW) {
            ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r,
                          "xlate input filter not added implicitly because %s",
                          !reqinfo->input_ctx ?
                          "no input configuration available" :
                          "another module added the filter");
        }
    }
}

/* stuff that sucks that I know of:
 *
 * bucket handling:
 *  why create an eos bucket when we see it come down the stream?  just send the one
 *  passed as input...  news flash: this will be fixed when xlate_out_filter() starts
 *  using the more generic xlate_brigade()
 *
 * translation mechanics:
 *   we don't handle characters that straddle more than two buckets; an error
 *   will be generated
 */

static apr_status_t send_bucket_downstream(ap_filter_t *f, apr_bucket *b)
{
    charset_filter_ctx_t *ctx = f->ctx;
    apr_status_t rv;

    APR_BRIGADE_INSERT_TAIL(ctx->tmpbb, b);
    rv = ap_pass_brigade(f->next, ctx->tmpbb);
    if (rv != APR_SUCCESS) {
        ctx->ees = EES_DOWNSTREAM;
    }