ngx_http_header_filter_module.c

Nginx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 <nginx.h>


static ngx_int_t ngx_http_header_filter_init(ngx_conf_t *cf);
static ngx_int_t ngx_http_header_filter(ngx_http_request_t *r);


static ngx_http_module_t  ngx_http_header_filter_module_ctx = {
    NULL,                                  /* preconfiguration */
    ngx_http_header_filter_init,           /* postconfiguration */

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

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

    NULL,                                  /* create location configuration */
    NULL,                                  /* merge location configuration */
};


ngx_module_t  ngx_http_header_filter_module = {
    NGX_MODULE_V1,
    &ngx_http_header_filter_module_ctx,    /* module context */
    NULL,                                  /* 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 char ngx_http_server_string[] = "Server: nginx" CRLF;
static char ngx_http_server_full_string[] = "Server: " NGINX_VER CRLF;


static ngx_str_t ngx_http_status_lines[] = {

    ngx_string("200 OK"),
    ngx_string("201 Created"),
    ngx_null_string,  /* "202 Accepted" */
    ngx_null_string,  /* "203 Non-Authoritative Information" */
    ngx_string("204 No Content"),
    ngx_null_string,  /* "205 Reset Content" */
    ngx_string("206 Partial Content"),

    /* ngx_null_string, */  /* "207 Multi-Status" */

#define NGX_HTTP_LEVEL_200  7

    /* ngx_null_string, */  /* "300 Multiple Choices" */

    ngx_string("301 Moved Permanently"),
    ngx_string("302 Moved Temporarily"),
    ngx_null_string,  /* "303 See Other" */
    ngx_string("304 Not Modified"),

    /* ngx_null_string, */  /* "305 Use Proxy" */
    /* ngx_null_string, */  /* "306 unused" */
    /* ngx_null_string, */  /* "307 Temporary Redirect" */

#define NGX_HTTP_LEVEL_300  4

    ngx_string("400 Bad Request"),
    ngx_string("401 Unauthorized"),
    ngx_string("402 Payment Required"),
    ngx_string("403 Forbidden"),
    ngx_string("404 Not Found"),
    ngx_string("405 Not Allowed"),
    ngx_string("406 Not Acceptable"),
    ngx_null_string,  /* "407 Proxy Authentication Required" */
    ngx_string("408 Request Time-out"),
    ngx_string("409 Conflict"),
    ngx_string("410 Gone"),
    ngx_string("411 Length Required"),
    ngx_string("412 Precondition Failed"),
    ngx_string("413 Request Entity Too Large"),
    ngx_null_string,  /* "414 Request-URI Too Large", but we never send it
                       * because we treat such requests as the HTTP/0.9
                       * requests and send only a body without a header
                       */
    ngx_string("415 Unsupported Media Type"),
    ngx_string("416 Requested Range Not Satisfiable"),

    /* ngx_null_string, */  /* "417 Expectation Failed" */
    /* ngx_null_string, */  /* "418 unused" */
    /* ngx_null_string, */  /* "419 unused" */
    /* ngx_null_string, */  /* "420 unused" */
    /* ngx_null_string, */  /* "421 unused" */
    /* ngx_null_string, */  /* "422 Unprocessable Entity" */
    /* ngx_null_string, */  /* "423 Locked" */
    /* ngx_null_string, */  /* "424 Failed Dependency" */

#define NGX_HTTP_LEVEL_400  17

    ngx_string("500 Internal Server Error"),
    ngx_string("501 Method Not Implemented"),
    ngx_string("502 Bad Gateway"),
    ngx_string("503 Service Temporarily Unavailable"),
    ngx_string("504 Gateway Time-out"),

    ngx_null_string,        /* "505 HTTP Version Not Supported" */
    ngx_null_string,        /* "506 Variant Also Negotiates" */
    ngx_string("507 Insufficient Storage"),
    /* ngx_null_string, */  /* "508 unused" */
    /* ngx_null_string, */  /* "509 unused" */
    /* ngx_null_string, */  /* "510 Not Extended" */
};


ngx_http_header_out_t  ngx_http_headers_out[] = {
    { ngx_string("Server"), offsetof(ngx_http_headers_out_t, server) },
    { ngx_string("Date"), offsetof(ngx_http_headers_out_t, date) },
#if 0
    { ngx_string("Content-Type"),
                 offsetof(ngx_http_headers_out_t, content_type) },
#endif
    { ngx_string("Content-Length"),
                 offsetof(ngx_http_headers_out_t, content_length) },
    { ngx_string("Content-Encoding"),
                 offsetof(ngx_http_headers_out_t, content_encoding) },
    { ngx_string("Location"), offsetof(ngx_http_headers_out_t, location) },
    { ngx_string("Last-Modified"),
                 offsetof(ngx_http_headers_out_t, last_modified) },
    { ngx_string("Accept-Ranges"),
                 offsetof(ngx_http_headers_out_t, accept_ranges) },
    { ngx_string("Expires"), offsetof(ngx_http_headers_out_t, expires) },
    { ngx_string("Cache-Control"),
                 offsetof(ngx_http_headers_out_t, cache_control) },
    { ngx_string("ETag"), offsetof(ngx_http_headers_out_t, etag) },

    { ngx_null_string, 0 }
};


static ngx_int_t
ngx_http_header_filter(ngx_http_request_t *r)
{
    u_char                    *p;
    size_t                     len;
    ngx_str_t                  host;
    ngx_buf_t                 *b;
    ngx_uint_t                 status, i;
    ngx_chain_t                out;
    ngx_list_part_t           *part;
    ngx_table_elt_t           *header;
    ngx_http_core_loc_conf_t  *clcf;
    ngx_http_core_srv_conf_t  *cscf;
    /* AF_INET only */
    u_char                     addr[INET_ADDRSTRLEN];

    r->header_sent = 1;

    if (r != r->main) {
        return NGX_OK;
    }

    if (r->http_version < NGX_HTTP_VERSION_10) {
        return NGX_OK;
    }

    if (r->method == NGX_HTTP_HEAD) {
        r->header_only = 1;
    }

    if (r->headers_out.last_modified_time != -1) {
        if (r->headers_out.status != NGX_HTTP_OK
            && r->headers_out.status != NGX_HTTP_PARTIAL_CONTENT
            && r->headers_out.status != NGX_HTTP_NOT_MODIFIED)
        {
            r->headers_out.last_modified_time = -1;
            r->headers_out.last_modified = NULL;
        }
    }

    len = sizeof("HTTP/1.x ") - 1 + sizeof(CRLF) - 1
          /* the end of the header */
          + sizeof(CRLF) - 1;

    /* status line */

    if (r->headers_out.status_line.len) {
        len += r->headers_out.status_line.len;
#if (NGX_SUPPRESS_WARN)
        status = NGX_INVALID_ARRAY_INDEX;
#endif

    } else {

        if (r->headers_out.status < NGX_HTTP_MOVED_PERMANENTLY) {
            /* 2XX */
            status = r->headers_out.status - NGX_HTTP_OK;

            if (r->headers_out.status == NGX_HTTP_NO_CONTENT) {
                r->header_only = 1;
                r->headers_out.content_type.len = 0;
                r->headers_out.content_type.data = NULL;
                r->headers_out.last_modified_time = -1;
                r->headers_out.last_modified = NULL;
                r->headers_out.content_length = NULL;
                r->headers_out.content_length_n = -1;
            }

        } else if (r->headers_out.status < NGX_HTTP_BAD_REQUEST) {
            /* 3XX */
            status = r->headers_out.status - NGX_HTTP_MOVED_PERMANENTLY
                                           + NGX_HTTP_LEVEL_200;

            if (r->headers_out.status == NGX_HTTP_NOT_MODIFIED) {
                r->header_only = 1;
            }

        } else if (r->headers_out.status < NGX_HTTP_INTERNAL_SERVER_ERROR) {
            /* 4XX */
            status = r->headers_out.status - NGX_HTTP_BAD_REQUEST
                                           + NGX_HTTP_LEVEL_200
                                           + NGX_HTTP_LEVEL_300;

        } else {
            /* 5XX */
            status = r->headers_out.status - NGX_HTTP_INTERNAL_SERVER_ERROR
                                           + NGX_HTTP_LEVEL_200
                                           + NGX_HTTP_LEVEL_300
                                           + NGX_HTTP_LEVEL_400;
        }

        len += ngx_http_status_lines[status].len;
    }

    clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module);

    if (r->headers_out.server == NULL) {
        len += clcf->server_tokens ? sizeof(ngx_http_server_full_string) - 1:
                                     sizeof(ngx_http_server_string) - 1;
    }

    if (r->headers_out.date == NULL) {
        len += sizeof("Date: Mon, 28 Sep 1970 06:00:00 GMT" CRLF) - 1;
    }

    if (r->headers_out.content_type.len) {
        len += sizeof("Content-Type: ") - 1
               + r->headers_out.content_type.len + 2;

        if (r->headers_out.content_type_len == r->headers_out.content_type.len
            && r->headers_out.charset.len)
        {
            len += sizeof("; charset=") - 1 + r->headers_out.charset.len;
        }
    }

    if (r->headers_out.content_length == NULL
        && r->headers_out.content_length_n >= 0)
    {
        len += sizeof("Content-Length: ") - 1 + NGX_OFF_T_LEN + 2;
    }

    if (r->headers_out.last_modified == NULL
        && r->headers_out.last_modified_time != -1)
    {
        len += sizeof("Last-Modified: Mon, 28 Sep 1970 06:00:00 GMT" CRLF) - 1;
    }

    if (r->headers_out.location
        && r->headers_out.location->value.len
        && r->headers_out.location->value.data[0] == '/')
    {
        r->headers_out.location->hash = 0;

        if (clcf->server_name_in_redirect) {
            cscf = ngx_http_get_module_srv_conf(r, ngx_http_core_module);