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

          * We can ignore Z_BUF_ERROR because:
          * When we call libz_func we can assume that
          *
          * - avail_in is zero (due to the surrounding code that calls
          *   flush_libz_buffer)
          * - avail_out is non zero due to our actions some lines above
          *
          * So the only reason for Z_BUF_ERROR is that the internal libz
          * buffers are now empty and thus we called libz_func one time
          * too often. This does not hurt. It simply says that we are done.
          */
         if (zRC == Z_BUF_ERROR) {
             zRC = Z_OK;
             break;
         }

         done = (ctx->stream.avail_out != 0 || zRC == Z_STREAM_END);

         if (zRC != Z_OK && zRC != Z_STREAM_END)
             break;
    }
    return zRC;
}

static apr_status_t deflate_ctx_cleanup(void *data)
{
    deflate_ctx *ctx = (deflate_ctx *)data;

    if (ctx)
        ctx->libz_end_func(&ctx->stream);
    return APR_SUCCESS;
}
/* PR 39727: we're screwing up our clients if we leave a strong ETag
 * header while transforming content.  Henrik Nordstrom suggests
 * appending ";gzip".
 *
 * Pending a more thorough review of our Etag handling, let's just
 * implement his suggestion.  It fixes the bug, or at least turns it
 * from a showstopper to an inefficiency.  And it breaks nothing that
 * wasn't already broken.
 */
static void deflate_check_etag(request_rec *r, const char *transform)
{
    const char *etag = apr_table_get(r->headers_out, "ETag");
    if (etag && (((etag[0] != 'W') && (etag[0] !='w')) || (etag[1] != '/'))) {
        apr_table_set(r->headers_out, "ETag",
                      apr_pstrcat(r->pool, etag, "-", transform, NULL));
    }
}
static apr_status_t deflate_out_filter(ap_filter_t *f,
                                       apr_bucket_brigade *bb)
{
    apr_bucket *e;
    request_rec *r = f->r;
    deflate_ctx *ctx = f->ctx;
    int zRC;
    deflate_filter_config *c;

    /* Do nothing if asked to filter nothing. */
    if (APR_BRIGADE_EMPTY(bb)) {
        return ap_pass_brigade(f->next, bb);
    }

    c = ap_get_module_config(r->server->module_config,
                             &deflate_module);

    /* If we don't have a context, we need to ensure that it is okay to send
     * the deflated content.  If we have a context, that means we've done
     * this before and we liked it.
     * This could be not so nice if we always fail.  But, if we succeed,
     * we're in better shape.
     */
    if (!ctx) {
        char *token;
        const char *encoding;

        /* only work on main request/no subrequests */
        if (r->main != NULL) {
            ap_remove_output_filter(f);
            return ap_pass_brigade(f->next, bb);
        }

        /* some browsers might have problems, so set no-gzip
         * (with browsermatch) for them
         */
        if (apr_table_get(r->subprocess_env, "no-gzip")) {
            ap_remove_output_filter(f);
            return ap_pass_brigade(f->next, bb);
        }

        /* We can't operate on Content-Ranges */
        if (apr_table_get(r->headers_out, "Content-Range") != NULL) {
            ap_remove_output_filter(f);
            return ap_pass_brigade(f->next, bb);
        }

        /* Some browsers might have problems with content types
         * other than text/html, so set gzip-only-text/html
         * (with browsermatch) for them
         */
        if (r->content_type == NULL
             || strncmp(r->content_type, "text/html", 9)) {
            const char *env_value = apr_table_get(r->subprocess_env,
                                                  "gzip-only-text/html");
            if ( env_value && (strcmp(env_value,"1") == 0) ) {
                ap_remove_output_filter(f);
                return ap_pass_brigade(f->next, bb);
            }
        }

        /* Let's see what our current Content-Encoding is.
         * If it's already encoded, don't compress again.
         * (We could, but let's not.)
         */
        encoding = apr_table_get(r->headers_out, "Content-Encoding");
        if (encoding) {
            const char *err_enc;

            err_enc = apr_table_get(r->err_headers_out, "Content-Encoding");
            if (err_enc) {
                encoding = apr_pstrcat(r->pool, encoding, ",", err_enc, NULL);
            }
        }
        else {
            encoding = apr_table_get(r->err_headers_out, "Content-Encoding");
        }

        if (r->content_encoding) {
            encoding = encoding ? apr_pstrcat(r->pool, encoding, ",",
                                              r->content_encoding, NULL)
                                : r->content_encoding;
        }

        if (encoding) {
            const char *tmp = encoding;

            token = ap_get_token(r->pool, &tmp, 0);
            while (token && *token) {
                /* stolen from mod_negotiation: */
                if (strcmp(token, "identity") && strcmp(token, "7bit") &&
                    strcmp(token, "8bit") && strcmp(token, "binary")) {

                    ap_remove_output_filter(f);
                    return ap_pass_brigade(f->next, bb);
                }

                /* Otherwise, skip token */
                if (*tmp) {
                    ++tmp;
                }
                token = (*tmp) ? ap_get_token(r->pool, &tmp, 0) : NULL;
            }
        }

        /* Even if we don't accept this request based on it not having
         * the Accept-Encoding, we need to note that we were looking
         * for this header and downstream proxies should be aware of that.
         */
        apr_table_mergen(r->headers_out, "Vary", "Accept-Encoding");

        /* force-gzip will just force it out regardless if the browser
         * can actually do anything with it.
         */
        if (!apr_table_get(r->subprocess_env, "force-gzip")) {
            const char *accepts;
            /* if they don't have the line, then they can't play */
            accepts = apr_table_get(r->headers_in, "Accept-Encoding");
            if (accepts == NULL) {
                ap_remove_output_filter(f);
                return ap_pass_brigade(f->next, bb);
            }

            token = ap_get_token(r->pool, &accepts, 0);
            while (token && token[0] && strcasecmp(token, "gzip")) {
                /* skip parameters, XXX: ;q=foo evaluation? */
                while (*accepts == ';') {
                    ++accepts;
                    token = ap_get_token(r->pool, &accepts, 1);
                }

                /* retrieve next token */
                if (*accepts == ',') {
                    ++accepts;
                }
                token = (*accepts) ? ap_get_token(r->pool, &accepts, 0) : NULL;
            }

            /* No acceptable token found. */
            if (token == NULL || token[0] == '\0') {
                ap_remove_output_filter(f);
                return ap_pass_brigade(f->next, bb);
            }
        }

        /* For a 304 or 204 response there is no entity included in
         * the response and hence nothing to deflate. */
        if (r->status == HTTP_NOT_MODIFIED || r->status == HTTP_NO_CONTENT) {
            ap_remove_output_filter(f);
            return ap_pass_brigade(f->next, bb);
        }

        /* We're cool with filtering this. */
        ctx = f->ctx = apr_pcalloc(r->pool, sizeof(*ctx));
        ctx->bb = apr_brigade_create(r->pool, f->c->bucket_alloc);
        ctx->buffer = apr_palloc(r->pool, c->bufferSize);
        ctx->libz_end_func = deflateEnd;

        zRC = deflateInit2(&ctx->stream, c->compressionlevel, Z_DEFLATED,
                           c->windowSize, c->memlevel,
                           Z_DEFAULT_STRATEGY);

        if (zRC != Z_OK) {
            deflateEnd(&ctx->stream);
            ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                          "unable to init Zlib: "
                          "deflateInit2 returned %d: URL %s",
                          zRC, r->uri);
            /*
             * Remove ourselves as it does not make sense to return:
             * We are not able to init libz and pass data down the chain
             * uncompressed.
             */
            ap_remove_output_filter(f);
            return ap_pass_brigade(f->next, bb);
        }
        /*
         * Register a cleanup function to ensure that we cleanup the internal
         * libz resources.
         */
        apr_pool_cleanup_register(r->pool, ctx, deflate_ctx_cleanup,
                                  apr_pool_cleanup_null);

        /* add immortal gzip header */
        e = apr_bucket_immortal_create(gzip_header, sizeof gzip_header,
                                       f->c->bucket_alloc);
        APR_BRIGADE_INSERT_TAIL(ctx->bb, e);

        /* If the entire Content-Encoding is "identity", we can replace it. */
        if (!encoding || !strcasecmp(encoding, "identity")) {
            apr_table_setn(r->headers_out, "Content-Encoding", "gzip");
        }
        else {
            apr_table_mergen(r->headers_out, "Content-Encoding", "gzip");
        }
        apr_table_unset(r->headers_out, "Content-Length");
        apr_table_unset(r->headers_out, "Content-MD5");
        deflate_check_etag(r, "gzip");

        /* initialize deflate output buffer */
        ctx->stream.next_out = ctx->buffer;
        ctx->stream.avail_out = c->bufferSize;
    }

    while (!APR_BRIGADE_EMPTY(bb))
    {
        const char *data;
        apr_bucket *b;
        apr_size_t len;

        e = APR_BRIGADE_FIRST(bb);

        if (APR_BUCKET_IS_EOS(e)) {
            char *buf;

            ctx->stream.avail_in = 0; /* should be zero already anyway */
            /* flush the remaining data from the zlib buffers */
            flush_libz_buffer(ctx, c, f->c->bucket_alloc, deflate, Z_FINISH,
                              NO_UPDATE_CRC);

            buf = apr_palloc(r->pool, VALIDATION_SIZE);
            putLong((unsigned char *)&buf[0], ctx->crc);
            putLong((unsigned char *)&buf[4], ctx->stream.total_in);

            b = apr_bucket_pool_create(buf, VALIDATION_SIZE, r->pool,
                                       f->c->bucket_alloc);
            APR_BRIGADE_INSERT_TAIL(ctx->bb, b);
            ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r,
                          "Zlib: Compressed %ld to %ld : URL %s",
                          ctx->stream.total_in, ctx->stream.total_out, r->uri);

            /* leave notes for logging */
            if (c->note_input_name) {
                apr_table_setn(r->notes, c->note_input_name,
                               (ctx->stream.total_in > 0)
                                ? apr_off_t_toa(r->pool,
                                                ctx->stream.total_in)
                                : "-");
            }

            if (c->note_output_name) {
                apr_table_setn(r->notes, c->note_output_name,
                               (ctx->stream.total_in > 0)
                                ? apr_off_t_toa(r->pool,
                                                ctx->stream.total_out)
                                : "-");
            }

            if (c->note_ratio_name) {
                apr_table_setn(r->notes, c->note_ratio_name,
                               (ctx->stream.total_in > 0)
                                ? apr_itoa(r->pool,
                                           (int)(ctx->stream.total_out
                                                 * 100
                                                 / ctx->stream.total_in))
                                : "-");
            }

            deflateEnd(&ctx->stream);
            /* No need for cleanup any longer */
            apr_pool_cleanup_kill(r->pool, ctx, deflate_ctx_cleanup);

            /* Remove EOS from the old list, and insert into the new. */
            APR_BUCKET_REMOVE(e);
            APR_BRIGADE_INSERT_TAIL(ctx->bb, e);

            /* Okay, we've seen the EOS.
             * Time to pass it along down the chain.
             */
            return ap_pass_brigade(f->next, ctx->bb);
        }

        if (APR_BUCKET_IS_FLUSH(e)) {
            apr_status_t rv;

            /* flush the remaining data from the zlib buffers */
            zRC = flush_libz_buffer(ctx, c, f->c->bucket_alloc, deflate,
                                    Z_SYNC_FLUSH, NO_UPDATE_CRC);
            if (zRC != Z_OK) {
                return APR_EGENERAL;
            }

            /* Remove flush bucket from old brigade anf insert into the new. */
            APR_BUCKET_REMOVE(e);
            APR_BRIGADE_INSERT_TAIL(ctx->bb, e);
            rv = ap_pass_brigade(f->next, ctx->bb);
            if (rv != APR_SUCCESS) {
                return rv;
            }
            continue;
        }

        if (APR_BUCKET_IS_METADATA(e)) {