mod_deflate.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.
 */

/*
 * mod_deflate.c: Perform deflate content-encoding on the fly
 *
 * Written by Ian Holsman, Justin Erenkrantz, and Nick Kew
 */

/*
 * Portions of this software are based upon zlib code by Jean-loup Gailly
 * (zlib functions gz_open and gzwrite, check_header)
 */

/* zlib flags */
#define ASCII_FLAG   0x01 /* bit 0 set: file probably ascii text */
#define HEAD_CRC     0x02 /* bit 1 set: header CRC present */
#define EXTRA_FIELD  0x04 /* bit 2 set: extra field present */
#define ORIG_NAME    0x08 /* bit 3 set: original file name present */
#define COMMENT      0x10 /* bit 4 set: file comment present */
#define RESERVED     0xE0 /* bits 5..7: reserved */


#include "httpd.h"
#include "http_config.h"
#include "http_log.h"
#include "apr_lib.h"
#include "apr_strings.h"
#include "apr_general.h"
#include "util_filter.h"
#include "apr_buckets.h"
#include "http_request.h"
#define APR_WANT_STRFUNC
#include "apr_want.h"

#include "zlib.h"

static const char deflateFilterName[] = "DEFLATE";
module AP_MODULE_DECLARE_DATA deflate_module;

typedef struct deflate_filter_config_t
{
    int windowSize;
    int memlevel;
    int compressionlevel;
    apr_size_t bufferSize;
    char *note_ratio_name;
    char *note_input_name;
    char *note_output_name;
} deflate_filter_config;

/* RFC 1952 Section 2.3 defines the gzip header:
 *
 * +---+---+---+---+---+---+---+---+---+---+
 * |ID1|ID2|CM |FLG|     MTIME     |XFL|OS |
 * +---+---+---+---+---+---+---+---+---+---+
 */
static const char gzip_header[10] =
{ '\037', '\213', Z_DEFLATED, 0,
  0, 0, 0, 0, /* mtime */
  0, 0x03 /* Unix OS_CODE */
};

/* magic header */
static const char deflate_magic[2] = { '\037', '\213' };

/* windowsize is negative to suppress Zlib header */
#define DEFAULT_COMPRESSION Z_DEFAULT_COMPRESSION
#define DEFAULT_WINDOWSIZE -15
#define DEFAULT_MEMLEVEL 9
#define DEFAULT_BUFFERSIZE 8096


/* Check whether a request is gzipped, so we can un-gzip it.
 * If a request has multiple encodings, we need the gzip
 * to be the outermost non-identity encoding.
 */
static int check_gzip(request_rec *r, apr_table_t *hdrs1, apr_table_t *hdrs2)
{
    int found = 0;
    apr_table_t *hdrs = hdrs1;
    const char *encoding = apr_table_get(hdrs, "Content-Encoding");

    if (!encoding && (hdrs2 != NULL)) {
        /* the output filter has two tables and a content_encoding to check */
        encoding = apr_table_get(hdrs2, "Content-Encoding");
        hdrs = hdrs2;
        if (!encoding) {
            encoding = r->content_encoding;
            hdrs = NULL;
        }
    }
    if (encoding && *encoding) {

        /* check the usual/simple case first */
        if (!strcasecmp(encoding, "gzip")
            || !strcasecmp(encoding, "x-gzip")) {
            found = 1;
            if (hdrs) {
                apr_table_unset(hdrs, "Content-Encoding");
            }
            else {
                r->content_encoding = NULL;
            }
        }
        else if (ap_strchr_c(encoding, ',') != NULL) {
            /* If the outermost encoding isn't gzip, there's nowt
             * we can do.  So only check the last non-identity token
             */
            char *new_encoding = apr_pstrdup(r->pool, encoding);
            char *ptr;
            for(;;) {
                char *token = ap_strrchr(new_encoding, ',');
                if (!token) {        /* gzip:identity or other:identity */
                    if (!strcasecmp(new_encoding, "gzip")
                        || !strcasecmp(new_encoding, "x-gzip")) {
                        found = 1;
                        if (hdrs) {
                            apr_table_unset(hdrs, "Content-Encoding");
                        }
                        else {
                            r->content_encoding = NULL;
                        }
                    }
                    break; /* seen all tokens */
                }
                for (ptr=token+1; apr_isspace(*ptr); ++ptr);
                if (!strcasecmp(ptr, "gzip")
                    || !strcasecmp(ptr, "x-gzip")) {
                    *token = '\0';
                    if (hdrs) {
                        apr_table_setn(hdrs, "Content-Encoding", new_encoding);
                    }
                    else {
                        r->content_encoding = new_encoding;
                    }
                    found = 1;
                }
                else if (!ptr[0] || !strcasecmp(ptr, "identity")) {
                    *token = '\0';
                    continue; /* strip the token and find the next one */
                }
                break; /* found a non-identity token */
            }
        }
    }
    return found;
}

/* Outputs a long in LSB order to the given file
 * only the bottom 4 bits are required for the deflate file format.
 */
static void putLong(unsigned char *string, unsigned long x)
{
    string[0] = (unsigned char)(x & 0xff);
    string[1] = (unsigned char)((x & 0xff00) >> 8);
    string[2] = (unsigned char)((x & 0xff0000) >> 16);
    string[3] = (unsigned char)((x & 0xff000000) >> 24);
}

/* Inputs a string and returns a long.
 */
static unsigned long getLong(unsigned char *string)
{
    return ((unsigned long)string[0])
          | (((unsigned long)string[1]) << 8)
          | (((unsigned long)string[2]) << 16)
          | (((unsigned long)string[3]) << 24);
}

static void *create_deflate_server_config(apr_pool_t *p, server_rec *s)
{
    deflate_filter_config *c = apr_pcalloc(p, sizeof *c);

    c->memlevel   = DEFAULT_MEMLEVEL;
    c->windowSize = DEFAULT_WINDOWSIZE;
    c->bufferSize = DEFAULT_BUFFERSIZE;
    c->compressionlevel = DEFAULT_COMPRESSION;

    return c;
}

static const char *deflate_set_window_size(cmd_parms *cmd, void *dummy,
                                           const char *arg)
{
    deflate_filter_config *c = ap_get_module_config(cmd->server->module_config,
                                                    &deflate_module);
    int i;

    i = atoi(arg);

    if (i < 1 || i > 15)
        return "DeflateWindowSize must be between 1 and 15";

    c->windowSize = i * -1;

    return NULL;
}

static const char *deflate_set_buffer_size(cmd_parms *cmd, void *dummy,
                                           const char *arg)
{
    deflate_filter_config *c = ap_get_module_config(cmd->server->module_config,
                                                    &deflate_module);
    int n = atoi(arg);

    if (n <= 0) {
        return "DeflateBufferSize should be positive";
    }

    c->bufferSize = (apr_size_t)n;

    return NULL;
}
static const char *deflate_set_note(cmd_parms *cmd, void *dummy,
                                    const char *arg1, const char *arg2)
{
    deflate_filter_config *c = ap_get_module_config(cmd->server->module_config,
                                                    &deflate_module);

    if (arg2 == NULL) {
        c->note_ratio_name = apr_pstrdup(cmd->pool, arg1);
    }
    else if (!strcasecmp(arg1, "ratio")) {
        c->note_ratio_name = apr_pstrdup(cmd->pool, arg2);
    }
    else if (!strcasecmp(arg1, "input")) {
        c->note_input_name = apr_pstrdup(cmd->pool, arg2);
    }
    else if (!strcasecmp(arg1, "output")) {
        c->note_output_name = apr_pstrdup(cmd->pool, arg2);
    }
    else {
        return apr_psprintf(cmd->pool, "Unknown note type %s", arg1);
    }

    return NULL;
}

static const char *deflate_set_memlevel(cmd_parms *cmd, void *dummy,
                                        const char *arg)
{
    deflate_filter_config *c = ap_get_module_config(cmd->server->module_config,
                                                    &deflate_module);
    int i;

    i = atoi(arg);

    if (i < 1 || i > 9)
        return "DeflateMemLevel must be between 1 and 9";

    c->memlevel = i;

    return NULL;
}

static const char *deflate_set_compressionlevel(cmd_parms *cmd, void *dummy,
                                        const char *arg)
{
    deflate_filter_config *c = ap_get_module_config(cmd->server->module_config,
                                                    &deflate_module);
    int i;

    i = atoi(arg);

    if (i < 1 || i > 9)
        return "Compression Level must be between 1 and 9";

    c->compressionlevel = i;

    return NULL;
}

typedef struct deflate_ctx_t
{
    z_stream stream;
    unsigned char *buffer;
    unsigned long crc;
    apr_bucket_brigade *bb, *proc_bb;
    int (*libz_end_func)(z_streamp);
    unsigned char *validation_buffer;
    apr_size_t validation_buffer_length;
    int inflate_init;
} deflate_ctx;

/* Number of validation bytes (CRC and length) after the compressed data */
#define VALIDATION_SIZE 8
/* Do not update ctx->crc, see comment in flush_libz_buffer */
#define NO_UPDATE_CRC 0
/* Do update ctx->crc, see comment in flush_libz_buffer */
#define UPDATE_CRC 1

static int flush_libz_buffer(deflate_ctx *ctx, deflate_filter_config *c,
                             struct apr_bucket_alloc_t *bucket_alloc,
                             int (*libz_func)(z_streamp, int), int flush,
                             int crc)
{
    int zRC = Z_OK;
    int done = 0;
    unsigned int deflate_len;
    apr_bucket *b;

    for (;;) {
         deflate_len = c->bufferSize - ctx->stream.avail_out;

         if (deflate_len != 0) {
             /*
              * Do we need to update ctx->crc? Usually this is the case for
              * inflate action where we need to do a crc on the output, whereas
              * in the deflate case we need to do a crc on the input
              */
             if (crc) {
                 ctx->crc = crc32(ctx->crc, (const Bytef *)ctx->buffer,
                                  deflate_len);
             }
             b = apr_bucket_heap_create((char *)ctx->buffer,
                                        deflate_len, NULL,
                                        bucket_alloc);
             APR_BRIGADE_INSERT_TAIL(ctx->bb, b);
             ctx->stream.next_out = ctx->buffer;
             ctx->stream.avail_out = c->bufferSize;
         }

         if (done)
             break;

         zRC = libz_func(&ctx->stream, flush);

         /*