ngx_http_gzip_filter_module.c

Nginx是一个高性能的HTTP和反向代理服务器

                           rc);

            ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                           "gzip in_buf:%p pos:%p",
                           ctx->in_buf, ctx->in_buf->pos);


            if (ctx->zstream.next_in) {
                ctx->in_buf->pos = ctx->zstream.next_in;

                if (ctx->zstream.avail_in == 0) {
                    ctx->zstream.next_in = NULL;
                }
            }

            ctx->out_buf->last = ctx->zstream.next_out;

            if (ctx->zstream.avail_out == 0) {

                /* zlib wants to output some more gzipped data */

                cl = ngx_alloc_chain_link(r->pool);
                if (cl == NULL) {
                    ngx_http_gzip_error(ctx);
                    return NGX_ERROR;
                }

                cl->buf = ctx->out_buf;
                cl->next = NULL;
                *ctx->last_out = cl;
                ctx->last_out = &cl->next;

                ctx->redo = 1;

                continue;
            }

            ctx->redo = 0;

            if (ctx->flush == Z_SYNC_FLUSH) {

                ctx->zstream.avail_out = 0;
                ctx->out_buf->flush = 1;
                ctx->flush = Z_NO_FLUSH;

                cl = ngx_alloc_chain_link(r->pool);
                if (cl == NULL) {
                    ngx_http_gzip_error(ctx);
                    return NGX_ERROR;
                }

                cl->buf = ctx->out_buf;
                cl->next = NULL;
                *ctx->last_out = cl;
                ctx->last_out = &cl->next;

                break;
            }

            if (rc == Z_STREAM_END) {

                ctx->zin = ctx->zstream.total_in;
                ctx->zout = 10 + ctx->zstream.total_out + 8;

                rc = deflateEnd(&ctx->zstream);

                if (rc != Z_OK) {
                    ngx_log_error(NGX_LOG_ALERT, r->connection->log, 0,
                                  "deflateEnd() failed: %d", rc);
                    ngx_http_gzip_error(ctx);
                    return NGX_ERROR;
                }

                ngx_pfree(r->pool, ctx->preallocated);

                cl = ngx_alloc_chain_link(r->pool);
                if (cl == NULL) {
                    ngx_http_gzip_error(ctx);
                    return NGX_ERROR;
                }

                cl->buf = ctx->out_buf;
                cl->next = NULL;
                *ctx->last_out = cl;
                ctx->last_out = &cl->next;

                if (ctx->zstream.avail_out >= 8) {
                    trailer = (struct gztrailer *) ctx->out_buf->last;
                    ctx->out_buf->last += 8;
                    ctx->out_buf->last_buf = 1;

                } else {
                    b = ngx_create_temp_buf(r->pool, 8);
                    if (b == NULL) {
                        ngx_http_gzip_error(ctx);
                        return NGX_ERROR;
                    }

                    b->last_buf = 1;

                    cl = ngx_alloc_chain_link(r->pool);
                    if (cl == NULL) {
                        ngx_http_gzip_error(ctx);
                        return NGX_ERROR;
                    }

                    cl->buf = b;
                    cl->next = NULL;
                    *ctx->last_out = cl;
                    ctx->last_out = &cl->next;
                    trailer = (struct gztrailer *) b->pos;
                    b->last += 8;
                }

#if (NGX_HAVE_LITTLE_ENDIAN && NGX_HAVE_NONALIGNED)

                trailer->crc32 = ctx->crc32;
                trailer->zlen = ctx->zin;

#else
                trailer->crc32[0] = (u_char) (ctx->crc32 & 0xff);
                trailer->crc32[1] = (u_char) ((ctx->crc32 >> 8) & 0xff);
                trailer->crc32[2] = (u_char) ((ctx->crc32 >> 16) & 0xff);
                trailer->crc32[3] = (u_char) ((ctx->crc32 >> 24) & 0xff);

                trailer->zlen[0] = (u_char) (ctx->zin & 0xff);
                trailer->zlen[1] = (u_char) ((ctx->zin >> 8) & 0xff);
                trailer->zlen[2] = (u_char) ((ctx->zin >> 16) & 0xff);
                trailer->zlen[3] = (u_char) ((ctx->zin >> 24) & 0xff);
#endif

                ctx->zstream.avail_in = 0;
                ctx->zstream.avail_out = 0;

                ctx->done = 1;

                r->connection->buffered &= ~NGX_HTTP_GZIP_BUFFERED;

                break;
            }

            if (conf->no_buffer && ctx->in == NULL) {

                cl = ngx_alloc_chain_link(r->pool);
                if (cl == NULL) {
                    ngx_http_gzip_error(ctx);
                    return NGX_ERROR;
                }

                cl->buf = ctx->out_buf;
                cl->next = NULL;
                *ctx->last_out = cl;
                ctx->last_out = &cl->next;

                break;
            }
        }

        if (ctx->out == NULL) {

            if (last == NGX_AGAIN) {
                return NGX_AGAIN;
            }

            if (ctx->busy == NULL) {
                return NGX_OK;
            }
        }

        last = ngx_http_next_body_filter(r, ctx->out);

        /*
         * we do not check NGX_AGAIN here because the downstream filters
         * may free some buffers and zlib may compress some data into them
         */

        if (last == NGX_ERROR) {
            ngx_http_gzip_error(ctx);
            return NGX_ERROR;
        }

        ngx_chain_update_chains(&ctx->free, &ctx->busy, &ctx->out,
                                (ngx_buf_tag_t) &ngx_http_gzip_filter_module);
        ctx->last_out = &ctx->out;

        if (ctx->done) {
            return last;
        }
    }
}


static void *
ngx_http_gzip_filter_alloc(void *opaque, u_int items, u_int size)
{
    ngx_http_gzip_ctx_t *ctx = opaque;

    void        *p;
    ngx_uint_t   alloc;

    alloc = items * size;

    if (alloc % 512 != 0) {

        /*
         * The zlib deflate_state allocation, it takes about 6K,
         * we allocate 8K.  Other allocations are divisible by 512.
         */

        alloc = (alloc + ngx_pagesize - 1) & ~(ngx_pagesize - 1);
    }

    if (alloc <= ctx->allocated) {
        p = ctx->free_mem;
        ctx->free_mem += alloc;
        ctx->allocated -= alloc;

        ngx_log_debug4(NGX_LOG_DEBUG_HTTP, ctx->request->connection->log, 0,
                       "gzip alloc: n:%ud s:%ud a:%ud p:%p",
                       items, size, alloc, p);

        return p;
    }

    ngx_log_error(NGX_LOG_ALERT, ctx->request->connection->log, 0,
                  "gzip filter failed to use preallocated memory: %ud of %ud",
                  items * size, ctx->allocated);

    p = ngx_palloc(ctx->request->pool, items * size);

    return p;
}


static void
ngx_http_gzip_filter_free(void *opaque, void *address)
{
#if 0
    ngx_http_gzip_ctx_t *ctx = opaque;

    ngx_log_debug1(NGX_LOG_DEBUG_HTTP, ctx->request->connection->log, 0,
                   "gzip free: %p", address);
#endif
}


static void
ngx_http_gzip_error(ngx_http_gzip_ctx_t *ctx)
{
    deflateEnd(&ctx->zstream);

    if (ctx->preallocated) {
        ngx_pfree(ctx->request->pool, ctx->preallocated);
    }

    ctx->zstream.avail_in = 0;
    ctx->zstream.avail_out = 0;

    ctx->done = 1;

    return;
}


static ngx_int_t
ngx_http_gzip_add_variables(ngx_conf_t *cf)
{
    ngx_http_variable_t  *var;

    var = ngx_http_add_variable(cf, &ngx_http_gzip_ratio, NGX_HTTP_VAR_NOHASH);
    if (var == NULL) {
        return NGX_ERROR;
    }

    var->get_handler = ngx_http_gzip_ratio_variable;

    return NGX_OK;
}


static ngx_int_t
ngx_http_gzip_ratio_variable(ngx_http_request_t *r,
    ngx_http_variable_value_t *v, uintptr_t data)
{
    ngx_uint_t            zint, zfrac;
    ngx_http_gzip_ctx_t  *ctx;

    v->valid = 1;
    v->no_cacheable = 0;
    v->not_found = 0;

    ctx = ngx_http_get_module_ctx(r, ngx_http_gzip_filter_module);

    if (ctx == NULL || ctx->zout == 0) {
        v->not_found = 1;
        return NGX_OK;
    }

    v->data = ngx_palloc(r->pool, NGX_INT32_LEN + 3);
    if (v->data == NULL) {
        return NGX_ERROR;
    }

    zint = (ngx_uint_t) (ctx->zin / ctx->zout);
    zfrac = (ngx_uint_t) ((ctx->zin * 100 / ctx->zout) % 100);

    if ((ctx->zin * 1000 / ctx->zout) % 10 > 4) {

        /* the rounding, e.g., 2.125 to 2.13 */

        zfrac++;

        if (zfrac > 99) {
            zint++;
            zfrac = 0;
        }
    }

    v->len = ngx_sprintf(v->data, "%ui.%02ui", zint, zfrac) - v->data;

    return NGX_OK;
}


static void *
ngx_http_gzip_create_conf(ngx_conf_t *cf)
{
    ngx_http_gzip_conf_t  *conf;

    conf = ngx_pcalloc(cf->pool, sizeof(ngx_http_gzip_conf_t));
    if (conf == NULL) {
        return NGX_CONF_ERROR;
    }

    /*
     * set by ngx_pcalloc():
     *
     *     conf->bufs.num = 0;
     *     conf->types = NULL;
     */

    conf->enable = NGX_CONF_UNSET;
    conf->no_buffer = NGX_CONF_UNSET;

    conf->level = NGX_CONF_UNSET;
    conf->wbits = (size_t) NGX_CONF_UNSET;
    conf->memlevel = (size_t) NGX_CONF_UNSET;
    conf->min_length = NGX_CONF_UNSET;

    return conf;
}


static char *
ngx_http_gzip_merge_conf(ngx_conf_t *cf, void *parent, void *child)
{
    ngx_http_gzip_conf_t *prev = parent;
    ngx_http_gzip_conf_t *conf = child;

    ngx_str_t  *type;

    ngx_conf_merge_value(conf->enable, prev->enable, 0);

    ngx_conf_merge_bufs_value(conf->bufs, prev->bufs, 4, ngx_pagesize);

    ngx_conf_merge_value(conf->level, prev->level, 1);
    ngx_conf_merge_size_value(conf->wbits, prev->wbits, MAX_WBITS);
    ngx_conf_merge_size_value(conf->memlevel, prev->memlevel,
                              MAX_MEM_LEVEL - 1);
    ngx_conf_merge_value(conf->min_length, prev->min_length, 20);
    ngx_conf_merge_value(conf->no_buffer, prev->no_buffer, 0);

    if (conf->types == NULL) {
        if (prev->types == NULL) {
            conf->types = ngx_array_create(cf->pool, 1, sizeof(ngx_str_t));
            if (conf->types == NULL) {
                return NGX_CONF_ERROR;
            }

            type = ngx_array_push(conf->types);
            if (type == NULL) {
                return NGX_CONF_ERROR;
            }

            type->len = sizeof("text/html") - 1;
            type->data = (u_char *) "text/html";

        } else {
            conf->types = prev->types;
        }
    }

    return NGX_CONF_OK;
}


static ngx_int_t
ngx_http_gzip_filter_init(ngx_conf_t *cf)
{
    ngx_http_next_header_filter = ngx_http_top_header_filter;
    ngx_http_top_header_filter = ngx_http_gzip_header_filter;

    ngx_http_next_body_filter = ngx_http_top_body_filter;
    ngx_http_top_body_filter = ngx_http_gzip_body_filter;

    return NGX_OK;
}


static char *
ngx_http_gzip_types(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
    ngx_http_gzip_conf_t *gcf = conf;

    ngx_str_t   *value, *type;
    ngx_uint_t   i;

    if (gcf->types == NULL) {
        gcf->types = ngx_array_create(cf->pool, 4, sizeof(ngx_str_t));
        if (gcf->types == NULL) {
            return NGX_CONF_ERROR;
        }

        type = ngx_array_push(gcf->types);
        if (type == NULL) {
            return NGX_CONF_ERROR;
        }

        type->len = sizeof("text/html") - 1;
        type->data = (u_char *) "text/html";
    }

    value = cf->args->elts;

    for (i = 1; i < cf->args->nelts; i++) {

        if (ngx_strcmp(value[i].data, "text/html") == 0) {
            continue;
        }

        type = ngx_array_push(gcf->types);
        if (type == NULL) {
            return NGX_CONF_ERROR;
        }

        type->len = value[i].len;

        type->data = ngx_palloc(cf->pool, type->len + 1);
        if (type->data == NULL) {
            return NGX_CONF_ERROR;
        }

        ngx_cpystrn(type->data, value[i].data, type->len + 1);
    }

    return NGX_CONF_OK;
}


static char *
ngx_http_gzip_window(ngx_conf_t *cf, void *post, void *data)
{
    int *np = data;

    int  wbits, wsize;

    wbits = 15;

    for (wsize = 32 * 1024; wsize > 256; wsize >>= 1) {

        if (wsize == *np) {
            *np = wbits;

            return NGX_CONF_OK;
        }

        wbits--;
    }

    return "must be 512, 1k, 2k, 4k, 8k, 16k, or 32k";
}


static char *
ngx_http_gzip_hash(ngx_conf_t *cf, void *post, void *data)
{
    int *np = data;

    int  memlevel, hsize;

    memlevel = 9;

    for (hsize = 128 * 1024; hsize > 256; hsize >>= 1) {

        if (hsize == *np) {
            *np = memlevel;

            return NGX_CONF_OK;
        }

        memlevel--;
    }

    return "must be 512, 1k, 2k, 4k, 8k, 16k, 32k, 64k, or 128k";
}