ngx_http_gzip_filter_module.c

Nginx ("engine x") 是一个高性能的 HTTP 和 反向代理 服务器

/*
 * Copyright (C) Igor Sysoev
 */


#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_http.h>

#include <zlib.h>


typedef struct {
    ngx_flag_t           enable;
    ngx_flag_t           no_buffer;
    ngx_flag_t           vary;

    ngx_array_t         *types;     /* array of ngx_str_t */

    ngx_bufs_t           bufs;

    ngx_uint_t           http_version;
    ngx_uint_t           proxied;

    ngx_int_t            level;
    size_t               wbits;
    size_t               memlevel;
    ssize_t              min_length;
} ngx_http_gzip_conf_t;


#define NGX_HTTP_GZIP_PROXIED_OFF       0x0002
#define NGX_HTTP_GZIP_PROXIED_EXPIRED   0x0004
#define NGX_HTTP_GZIP_PROXIED_NO_CACHE  0x0008
#define NGX_HTTP_GZIP_PROXIED_NO_STORE  0x0010
#define NGX_HTTP_GZIP_PROXIED_PRIVATE   0x0020
#define NGX_HTTP_GZIP_PROXIED_NO_LM     0x0040
#define NGX_HTTP_GZIP_PROXIED_NO_ETAG   0x0080
#define NGX_HTTP_GZIP_PROXIED_AUTH      0x0100
#define NGX_HTTP_GZIP_PROXIED_ANY       0x0200


typedef struct {
    ngx_chain_t         *in;
    ngx_chain_t         *free;
    ngx_chain_t         *busy;
    ngx_chain_t         *out;
    ngx_chain_t        **last_out;
    ngx_buf_t           *in_buf;
    ngx_buf_t           *out_buf;
    ngx_int_t            bufs;

    off_t                length;

    void                *preallocated;
    char                *free_mem;
    ngx_uint_t           allocated;

    unsigned             flush:4;
    unsigned             redo:1;
    unsigned             done:1;

    size_t               zin;
    size_t               zout;

    uint32_t             crc32;
    z_stream             zstream;
    ngx_http_request_t  *request;
} ngx_http_gzip_ctx_t;


static ngx_int_t ngx_http_gzip_proxied(ngx_http_request_t *r,
    ngx_http_gzip_conf_t *conf);
static void *ngx_http_gzip_filter_alloc(void *opaque, u_int items,
    u_int size);
static void ngx_http_gzip_filter_free(void *opaque, void *address);
static void ngx_http_gzip_error(ngx_http_gzip_ctx_t *ctx);

static ngx_int_t ngx_http_gzip_add_variables(ngx_conf_t *cf);
static ngx_int_t ngx_http_gzip_ratio_variable(ngx_http_request_t *r,
    ngx_http_variable_value_t *v, uintptr_t data);

static ngx_int_t ngx_http_gzip_filter_init(ngx_conf_t *cf);
static void *ngx_http_gzip_create_conf(ngx_conf_t *cf);
static char *ngx_http_gzip_merge_conf(ngx_conf_t *cf,
    void *parent, void *child);
static char *ngx_http_gzip_types(ngx_conf_t *cf, ngx_command_t *cmd,
    void *conf);
static char *ngx_http_gzip_window(ngx_conf_t *cf, void *post, void *data);
static char *ngx_http_gzip_hash(ngx_conf_t *cf, void *post, void *data);


static ngx_conf_num_bounds_t  ngx_http_gzip_comp_level_bounds = {
    ngx_conf_check_num_bounds, 1, 9
};

static ngx_conf_post_handler_pt  ngx_http_gzip_window_p = ngx_http_gzip_window;
static ngx_conf_post_handler_pt  ngx_http_gzip_hash_p = ngx_http_gzip_hash;


static ngx_conf_enum_t  ngx_http_gzip_http_version[] = {
    { ngx_string("1.0"), NGX_HTTP_VERSION_10 },
    { ngx_string("1.1"), NGX_HTTP_VERSION_11 },
    { ngx_null_string, 0 }
};


static ngx_conf_bitmask_t  ngx_http_gzip_proxied_mask[] = {
    { ngx_string("off"), NGX_HTTP_GZIP_PROXIED_OFF },
    { ngx_string("expired"), NGX_HTTP_GZIP_PROXIED_EXPIRED },
    { ngx_string("no-cache"), NGX_HTTP_GZIP_PROXIED_NO_CACHE },
    { ngx_string("no-store"), NGX_HTTP_GZIP_PROXIED_NO_STORE },
    { ngx_string("private"), NGX_HTTP_GZIP_PROXIED_PRIVATE },
    { ngx_string("no_last_modified"), NGX_HTTP_GZIP_PROXIED_NO_LM },
    { ngx_string("no_etag"), NGX_HTTP_GZIP_PROXIED_NO_ETAG },
    { ngx_string("auth"), NGX_HTTP_GZIP_PROXIED_AUTH },
    { ngx_string("any"), NGX_HTTP_GZIP_PROXIED_ANY },
    { ngx_null_string, 0 }
};


static ngx_command_t  ngx_http_gzip_filter_commands[] = {

    { ngx_string("gzip"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_HTTP_LIF_CONF
                        |NGX_CONF_FLAG,
      ngx_conf_set_flag_slot,
      NGX_HTTP_LOC_CONF_OFFSET,
      offsetof(ngx_http_gzip_conf_t, enable),
      NULL },

    { ngx_string("gzip_buffers"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE2,
      ngx_conf_set_bufs_slot,
      NGX_HTTP_LOC_CONF_OFFSET,
      offsetof(ngx_http_gzip_conf_t, bufs),
      NULL },

    { ngx_string("gzip_types"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_1MORE,
      ngx_http_gzip_types,
      NGX_HTTP_LOC_CONF_OFFSET,
      0,
      NULL },

    { ngx_string("gzip_comp_level"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_num_slot,
      NGX_HTTP_LOC_CONF_OFFSET,
      offsetof(ngx_http_gzip_conf_t, level),
      &ngx_http_gzip_comp_level_bounds },

    { ngx_string("gzip_window"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_size_slot,
      NGX_HTTP_LOC_CONF_OFFSET,
      offsetof(ngx_http_gzip_conf_t, wbits),
      &ngx_http_gzip_window_p },

    { ngx_string("gzip_hash"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_size_slot,
      NGX_HTTP_LOC_CONF_OFFSET,
      offsetof(ngx_http_gzip_conf_t, memlevel),
      &ngx_http_gzip_hash_p },

    { ngx_string("gzip_no_buffer"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_FLAG,
      ngx_conf_set_flag_slot,
      NGX_HTTP_LOC_CONF_OFFSET,
      offsetof(ngx_http_gzip_conf_t, no_buffer),
      NULL },

    { ngx_string("gzip_http_version"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_enum_slot,
      NGX_HTTP_LOC_CONF_OFFSET,
      offsetof(ngx_http_gzip_conf_t, http_version),
      &ngx_http_gzip_http_version },

    { ngx_string("gzip_proxied"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_1MORE,
      ngx_conf_set_bitmask_slot,
      NGX_HTTP_LOC_CONF_OFFSET,
      offsetof(ngx_http_gzip_conf_t, proxied),
      &ngx_http_gzip_proxied_mask },

    { ngx_string("gzip_min_length"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_size_slot,
      NGX_HTTP_LOC_CONF_OFFSET,
      offsetof(ngx_http_gzip_conf_t, min_length),
      NULL },

    { ngx_string("gzip_vary"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_FLAG,
      ngx_conf_set_flag_slot,
      NGX_HTTP_LOC_CONF_OFFSET,
      offsetof(ngx_http_gzip_conf_t, vary),
      NULL },

      ngx_null_command
};


static ngx_http_module_t  ngx_http_gzip_filter_module_ctx = {
    ngx_http_gzip_add_variables,           /* preconfiguration */
    ngx_http_gzip_filter_init,             /* postconfiguration */

    NULL,                                  /* create main configuration */
    NULL,                                  /* init main configuration */

    NULL,                                  /* create server configuration */
    NULL,                                  /* merge server configuration */

    ngx_http_gzip_create_conf,             /* create location configuration */
    ngx_http_gzip_merge_conf               /* merge location configuration */
};


ngx_module_t  ngx_http_gzip_filter_module = {
    NGX_MODULE_V1,
    &ngx_http_gzip_filter_module_ctx,      /* module context */
    ngx_http_gzip_filter_commands,         /* module directives */
    NGX_HTTP_MODULE,                       /* module type */
    NULL,                                  /* init master */
    NULL,                                  /* init module */
    NULL,                                  /* init process */
    NULL,                                  /* init thread */
    NULL,                                  /* exit thread */
    NULL,                                  /* exit process */
    NULL,                                  /* exit master */
    NGX_MODULE_V1_PADDING
};


static u_char  gzheader[10] = { 0x1f, 0x8b, Z_DEFLATED, 0, 0, 0, 0, 0, 0, 3 };

#if (NGX_HAVE_LITTLE_ENDIAN && NGX_HAVE_NONALIGNED)

struct gztrailer {
    uint32_t  crc32;
    uint32_t  zlen;
};

#else /* NGX_HAVE_BIG_ENDIAN || !NGX_HAVE_NONALIGNED */

struct gztrailer {
    u_char  crc32[4];
    u_char  zlen[4];
};

#endif


static ngx_str_t  ngx_http_gzip_ratio = ngx_string("gzip_ratio");
static ngx_str_t  ngx_http_gzip_no_cache = ngx_string("no-cache");
static ngx_str_t  ngx_http_gzip_no_store = ngx_string("no-store");
static ngx_str_t  ngx_http_gzip_private = ngx_string("private");


static ngx_http_output_header_filter_pt  ngx_http_next_header_filter;
static ngx_http_output_body_filter_pt    ngx_http_next_body_filter;


static ngx_int_t
ngx_http_gzip_header_filter(ngx_http_request_t *r)
{
    ngx_str_t             *type;
    ngx_uint_t             i;
    ngx_table_elt_t       *header;
    ngx_http_gzip_ctx_t   *ctx;
    ngx_http_gzip_conf_t  *conf;

    conf = ngx_http_get_module_loc_conf(r, ngx_http_gzip_filter_module);

    if (!conf->enable
        || (r->headers_out.status != NGX_HTTP_OK
            && r->headers_out.status != NGX_HTTP_FORBIDDEN
            && r->headers_out.status != NGX_HTTP_NOT_FOUND)
        || r->header_only
        || r != r->main
        || r->http_version < conf->http_version
        || r->headers_out.content_type.len == 0
        || (r->headers_out.content_encoding
            && r->headers_out.content_encoding->value.len)
        || r->headers_in.accept_encoding == NULL
        || (r->headers_out.content_length_n != -1
            && r->headers_out.content_length_n < conf->min_length)
        || ngx_strcasestrn(r->headers_in.accept_encoding->value.data,
                           "gzip", 4 - 1)
           == NULL
       )
    {
        return ngx_http_next_header_filter(r);
    }


    type = conf->types->elts;
    for (i = 0; i < conf->types->nelts; i++) {
        if (r->headers_out.content_type.len >= type[i].len
            && ngx_strncasecmp(r->headers_out.content_type.data,
                               type[i].data, type[i].len) == 0)
        {
            goto found;
        }
    }

    return ngx_http_next_header_filter(r);


found:

    if (r->headers_in.via) {
        if (conf->proxied & NGX_HTTP_GZIP_PROXIED_OFF) {
            return ngx_http_next_header_filter(r);
        }

        if (!(conf->proxied & NGX_HTTP_GZIP_PROXIED_ANY)
            && ngx_http_gzip_proxied(r, conf) == NGX_DECLINED)
        {
            return ngx_http_next_header_filter(r);
        }
    }


    /*
     * if the URL (without the "http://" prefix) is longer than 253 bytes
     * then MSIE 4.x can not handle the compressed stream - it waits too long,
     * hangs up or crashes
     */

    if (r->headers_in.msie4 && r->unparsed_uri.len > 200) {
        return ngx_http_next_header_filter(r);
    }

    ctx = ngx_pcalloc(r->pool, sizeof(ngx_http_gzip_ctx_t));
    if (ctx == NULL) {
        return NGX_ERROR;
    }

    ngx_http_set_ctx(r, ctx, ngx_http_gzip_filter_module);


    ctx->request = r;

    header = ngx_list_push(&r->headers_out.headers);
    if (header == NULL) {
        return NGX_ERROR;
    }

    header->hash = 1;
    header->key.len = sizeof("Content-Encoding") - 1;
    header->key.data = (u_char *) "Content-Encoding";
    header->value.len = sizeof("gzip") - 1;
    header->value.data = (u_char *) "gzip";

    r->headers_out.content_encoding = header;

    if (conf->vary) {
        header = ngx_list_push(&r->headers_out.headers);
        if (header == NULL) {
            return NGX_ERROR;
        }

        header->hash = 1;
        header->key.len = sizeof("Vary") - 1;
        header->key.data = (u_char *) "Vary";
        header->value.len = sizeof("Accept-Encoding") - 1;
        header->value.data = (u_char *) "Accept-Encoding";
    }

    ctx->length = r->headers_out.content_length_n;

    r->main_filter_need_in_memory = 1;

    ngx_http_clear_content_length(r);
    ngx_http_clear_accept_ranges(r);

    return ngx_http_next_header_filter(r);
}


static ngx_int_t
ngx_http_gzip_proxied(ngx_http_request_t *r, ngx_http_gzip_conf_t *conf)
{
    time_t  date, expires;

    if (r->headers_in.authorization
        && (conf->proxied & NGX_HTTP_GZIP_PROXIED_AUTH))
    {
        return NGX_OK;
    }

    if (r->headers_out.expires) {

        if (!(conf->proxied & NGX_HTTP_GZIP_PROXIED_EXPIRED)) {
            return NGX_DECLINED;