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nginx源码笔记

分类： C/C++

2013-11-21 09:38:52

一、模块类型
在对nginx进行编译的时候，会在objs目录下 动态生成如下ngx_modules.c文件，里面有如下指针数组，保存的是当前nginx里编译进入的各个模块。
其中从Line 2-9 的这几个模块是nginx的 NGX_CORE_MODULE，属于第一级模块。后面的模块都是基于CORE模块细分出来的，比如NGX_HTTP_MODULE。  还有一个模块NGX_CONF_MODULE，目前只有一个命令使用“include”。

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  1. ngx_module_t *ngx_modules[] = {
  2.     &ngx_core_module,
  3.     &ngx_errlog_module,
  4.     &ngx_conf_module,
  5.     &ngx_events_module,
  6.     &ngx_event_core_module,
  7.     &ngx_epoll_module,
  8.     &ngx_regex_module,
  9.     &ngx_http_module,
  10.     &ngx_http_core_module,
  11.     &ngx_http_log_module,
  12.     &ngx_http_upstream_module,
  13.     &ngx_http_static_module,
  14.     &ngx_http_autoindex_module,
  15.     &ngx_http_index_module,
  16.     &ngx_http_auth_basic_module,
  17.     &ngx_http_access_module,
  18.     &ngx_http_limit_conn_module,
  19.     &ngx_http_limit_req_module,
  20.     &ngx_http_geo_module,
  21.     &ngx_http_map_module,
  22.     &ngx_http_split_clients_module,
  23.     &ngx_http_referer_module,
  24.     &ngx_http_rewrite_module,
  25.     &ngx_http_proxy_module,
  26.     &ngx_http_fastcgi_module,
  27.     &ngx_http_uwsgi_module,
  28.     &ngx_http_scgi_module,
  29.     &ngx_http_memcached_module,
  30.     &ngx_http_empty_gif_module,
  31.     &ngx_http_browser_module,
  32.     &ngx_http_upstream_ip_hash_module,
  33.     &ngx_http_upstream_least_conn_module,
  34.     &ngx_http_upstream_keepalive_module,
  35.     &ngx_http_write_filter_module,
  36.     &ngx_http_header_filter_module,
  37.     &ngx_http_chunked_filter_module,
  38.     &ngx_http_range_header_filter_module,
  39.     &ngx_http_gzip_filter_module,
  40.     &ngx_http_postpone_filter_module,
  41.     &ngx_http_ssi_filter_module,
  42.     &ngx_http_charset_filter_module,
  43.     &ngx_http_userid_filter_module,
  44.     &ngx_http_headers_filter_module,
  45.     &ngx_http_copy_filter_module,
  46.     &ngx_http_range_body_filter_module,
  47.     &ngx_http_not_modified_filter_module,
  48.     NULL
  49. };

 二、遍历每个CORE模块，进行 配置解析

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  1. static ngx_int_t
  2. ngx_conf_handler(ngx_conf_t *cf, ngx_int_t last)
  3. {
  4.     char *rv;
  5.     void *conf, **confp;
  6.     ngx_uint_t i, found;
  7.     ngx_str_t *name;
  8.     ngx_command_t *cmd;

  10.     name = cf->args->elts;

  12.     found = 0;

  14.     for (i = 0; ngx_modules[i]; i++) {

  16.         cmd = ngx_modules[i]->commands;
  17.         if (cmd == NULL) {
  18.             continue;
  19.         }

  21.         for ( /* void */ ; cmd->name.len; cmd++) {

  23.             if (name->len != cmd->name.len) {
  24.                 continue;
  25.             }

  27.             if (ngx_strcmp(name->data, cmd->name.data) != 0) {
  28.                 continue;
  29.             }

  31.             found = 1;

  33.             if (ngx_modules[i]->type != NGX_CONF_MODULE
  34.                 && ngx_modules[i]->type != cf->module_type)
  35.             {
  36.                 continue;
  37.             }

  39.             /* is the directive's location right ? */
  40.             //指令的Context必须当前解析Context相符
  41.             if (!(cmd->type & cf->cmd_type)) {
  42.                 continue;
  43.             }

  44.             //非块指令必须以“;”结尾
  45.             if (!(cmd->type & NGX_CONF_BLOCK) && last != NGX_OK) {
  46.                 ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
  47.                                   "directive \"%s\" is not terminated by \";\"",
  48.                                   name->data);
  49.                 return NGX_ERROR;
  50.             }

  51.             //块指令必须后接“{”；
  52.             if ((cmd->type & NGX_CONF_BLOCK) && last != NGX_CONF_BLOCK_START) {
  53.                 ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
  54.                                    "directive \"%s\" has no opening \"{\"",
  55.                                    name->data);
  56.                 return NGX_ERROR;
  57.             }

  59.             /* is the directive's argument count right ? */

  60.             //指令参数个数必须正确。注意指令参数有最大值NGX_CONF_MAX_ARGS，目前值为8。
  61.             if (!(cmd->type & NGX_CONF_ANY)) {

  63.                 if (cmd->type & NGX_CONF_FLAG) {

  65.                     if (cf->args->nelts != 2) {
  66.                         goto invalid;
  67.                     }

  69.                 } else if (cmd->type & NGX_CONF_1MORE) {

  71.                     if (cf->args->nelts < 2) {
  72.                         goto invalid;
  73.                     }

  75.                 } else if (cmd->type & NGX_CONF_2MORE) {

  77.                     if (cf->args->nelts < 3) {
  78.                         goto invalid;
  79.                     }

  81.                 } else if (cf->args->nelts > NGX_CONF_MAX_ARGS) {

  83.                     goto invalid;

  85.                 } else if (!(cmd->type & argument_number[cf->args->nelts - 1]))
  86.                 {
  87.                     goto invalid;
  88.                 }
  89.             }

  91.             /* set up the directive's configuration context */

  92.             //取得指令工作的conf指针
  93.             conf = NULL;

  94. /*
    * NGX_DIRECT_CONF为什么是direct(直接)，这类命令字只出现在core模块里
    * direct字面理解是需要使用（赋值）时候可以直接拿来使用即可，即在调用前上下文结构已经分配好，如worker_processes指令
    * 对应的非direct则需要先分配空间后才能使用，如http指令(http是一个指令，不是一类指令）。nginx在解析配置文件之前，会依次调用NGX_CORE_MODULE 模块的create_conf，direct指令的上下文就是这个时候分配的.
  95. */
  96.             if (cmd->type & NGX_DIRECT_CONF) {
  97.                 conf = ((void **) cf->ctx)[ngx_modules[i]->index];

  98.             //指的属于block的内容，比如http，event等
  99.             } else if (cmd->type & NGX_MAIN_CONF) {
  100.                 conf = &(((void **) cf->ctx)[ngx_modules[i]->index]);

  101.             //其他指令，主要是 “{}”之内的指令
  102.             } else if (cf->ctx) {
                    //其中 cmd->conf对于http来说是针对ngx_http_conf_ctx_t中成员的偏移，比如main-0、server-8、local-16。
  103. /*
    * cmd->conf是什么？set指令的conf是 NGX_HTTP_LOC_CONF_OFFSET(ngx_http_rewrite_module.c:81)
    * #define NGX_HTTP_LOC_CONF_OFFSET   offsetof(ngx_http_conf_ctx_t, loc_conf)
    * 通过上面的宏定义，清楚可以知道cmd->conf返回的是一个变量在struct里的偏移
    * nginx为每个http模块提供的上下文结构(ngx_http_conf_ctx_t)包括main_conf, srv_conf, loc_conf 三个元素；
    * 对于一个指令而言，只会用到上下文结构中的一个*_conf；但对于一个模块（包含多个指令）而言，可能会用到任意多个*_conf。
    * set指令可以运行在location和server，set指令的上下文结构又保存在srv_conf or loc_conf？请独立思考来验证自己是否已经对模块有一定理解。
    */
  104.                 confp = *(void **) ((char *) cf->ctx + cmd->conf);

  106.                 if (confp) {
                        //ngx_modules[i]->ctx_index表示这个模块在当前CORE模块，如HTTP模块中的排序编号，ngx_modules[i]->index表示这个模块在所有NGX模块中的排序编号
  107.                     conf = confp[ngx_modules[i]->ctx_index];
  108.                 }
  109.             }

  111.             rv = cmd->set(cf, cmd, conf);

  113.             if (rv == NGX_CONF_OK) {
  114.                 return NGX_OK;
  115.             }

  117.             if (rv == NGX_CONF_ERROR) {
  118.                 return NGX_ERROR;
  119.             }

  121.             ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
  122.                                "\"%s\" directive %s", name->data, rv);

  124.             return NGX_ERROR;
  125.         }
  126.     }

  128.     if (found) {
  129.         ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
  130.                            "\"%s\" directive is not allowed here", name->data);

  132.         return NGX_ERROR;
  133.     }

  135.     ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
  136.                        "unknown directive \"%s\"", name->data);

  138.     return NGX_ERROR;

  140. invalid:

  142.     ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
  143.                        "invalid number of arguments in \"%s\" directive",
  144.                        name->data);

  146.     return NGX_ERROR;
  147. }
其中cmd->type的取值： 

点击(此处)折叠或打开

  1. #define NGX_CONF_NOARGS 0x00000001
  2. #define NGX_CONF_TAKE1 0x00000002
  3. #define NGX_CONF_TAKE2 0x00000004
  4. #define NGX_CONF_TAKE3 0x00000008
  5. #define NGX_CONF_TAKE4 0x00000010
  6. #define NGX_CONF_TAKE5 0x00000020
  7. #define NGX_CONF_TAKE6 0x00000040
  8. #define NGX_CONF_TAKE7 0x00000080

  10. #define NGX_CONF_MAX_ARGS 8

  12. #define NGX_CONF_TAKE12 (NGX_CONF_TAKE1|NGX_CONF_TAKE2)
  13. #define NGX_CONF_TAKE13 (NGX_CONF_TAKE1|NGX_CONF_TAKE3)

  15. #define NGX_CONF_TAKE23 (NGX_CONF_TAKE2|NGX_CONF_TAKE3)

  17. #define NGX_CONF_TAKE123 (NGX_CONF_TAKE1|NGX_CONF_TAKE2|NGX_CONF_TAKE3)
  18. #define NGX_CONF_TAKE1234 (NGX_CONF_TAKE1|NGX_CONF_TAKE2|NGX_CONF_TAKE3|NGX_CONF_TAKE4)

  20. #define NGX_CONF_ARGS_NUMBER 0x000000ff
  21. #define NGX_CONF_BLOCK 0x00000100
  22. #define NGX_CONF_FLAG 0x00000200
  23. #define NGX_CONF_ANY 0x00000400
  24. #define NGX_CONF_1MORE 0x00000800
  25. #define NGX_CONF_2MORE 0x00001000
  26. #define NGX_CONF_MULTI 0x00000000

  28. #define NGX_DIRECT_CONF 0x00010000

  30. #define NGX_MAIN_CONF 0x01000000
  31. #define NGX_ANY_CONF 0x0F000000

  32.  
  33. #define NGX_HTTP_MAIN_CONF 0x02000000
  34. #define NGX_HTTP_SRV_CONF 0x04000000
  35. #define NGX_HTTP_LOC_CONF 0x08000000
  36. #define NGX_HTTP_UPS_CONF 0x10000000
  37. #define NGX_HTTP_SIF_CONF 0x20000000
  38. #define NGX_HTTP_LIF_CONF 0x40000000
  39. #define NGX_HTTP_LMT_CONF 0x80000000

  41. #define NGX_EVENT_CONF 0x02000000

  43. #define NGX_MAIL_MAIN_CONF 0x02000000
  44. #define NGX_MAIL_SRV_CONF 0x04000000
cf->cmd_type 的取值：

点击(此处)折叠或打开

  1. #define NGX_MAIN_CONF 0x01000000
  2. #define NGX_ANY_CONF 0x0F000000

  4. #define NGX_HTTP_MAIN_CONF 0x02000000
  5. #define NGX_HTTP_SRV_CONF 0x04000000
  6. #define NGX_HTTP_LOC_CONF 0x08000000
  7. #define NGX_HTTP_UPS_CONF 0x10000000
  8. #define NGX_HTTP_SIF_CONF 0x20000000
  9. #define NGX_HTTP_LIF_CONF 0x40000000
  10. #define NGX_HTTP_LMT_CONF 0x80000000

  12. #define NGX_EVENT_CONF 0x02000000

  14. #define NGX_MAIL_MAIN_CONF 0x02000000
  15. #define NGX_MAIL_SRV_CONF 0x04000000
四、解析http block模块

点击(此处)折叠或打开

  1. static char *
  2. ngx_http_block(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
  3. {
  4.     char *rv;
  5.     ngx_uint_t mi, m, s;
  6.     ngx_conf_t pcf;
  7.     ngx_http_module_t *module;
  8.     ngx_http_conf_ctx_t *ctx;
  9.     ngx_http_core_loc_conf_t *clcf;
  10.     ngx_http_core_srv_conf_t **cscfp;
  11.     ngx_http_core_main_conf_t *cmcf;

  13.     /* the main http context */

  15.     ctx = ngx_pcalloc(cf->pool, sizeof(ngx_http_conf_ctx_t));
  16.     if (ctx == NULL) {
  17.         return NGX_CONF_ERROR;
  18.     }
  19.  /*

    * 注意，传进来的conf被修改了。

    * 因为http_module虽是core模块，但是并没有定义create_conf，所以步骤一并没有为http_module分配上下文空间

    * http指令是NGX_MAIN_CONF，所以conf传入的实质是一个指针的指针

    * 所以通过在这里重新赋值，来为conf分配空间

    */

  20.     *(ngx_http_conf_ctx_t **) conf = ctx;


  23.     /* count the number of the http modules and set up their indices */

  25.     ngx_http_max_module = 0;
  26.     for (m = 0; ngx_modules[m]; m++) {
  27.         if (ngx_modules[m]->type != NGX_HTTP_MODULE) {
  28.             continue;
  29.         }

  31.         ngx_modules[m]->ctx_index = ngx_http_max_module++;
  32.     }


  35.     /* the http main_conf context, it is the same in the all http contexts */

  37.     ctx->main_conf = ngx_pcalloc(cf->pool,
  38.                                  sizeof(void *) * ngx_http_max_module);
  39.     if (ctx->main_conf == NULL) {
  40.         return NGX_CONF_ERROR;
  41.     }


  44.     /*
  45.      * the http null srv_conf context, it is used to merge
  46.      * the server{}s' srv_conf's
  47.      */

  49.     ctx->srv_conf = ngx_pcalloc(cf->pool, sizeof(void *) * ngx_http_max_module);
  50.     if (ctx->srv_conf == NULL) {
  51.         return NGX_CONF_ERROR;
  52.     }


  55.     /*
  56.      * the http null loc_conf context, it is used to merge
  57.      * the server{}s' loc_conf's
  58.      */

  60.     ctx->loc_conf = ngx_pcalloc(cf->pool, sizeof(void *) * ngx_http_max_module);
  61.     if (ctx->loc_conf == NULL) {
  62.         return NGX_CONF_ERROR;
  63.     }


  66.     /*
  67.      * create the main_conf's, the null srv_conf's, and the null loc_conf's
  68.      * of the all http modules
  69.      */

  71.     for (m = 0; ngx_modules[m]; m++) {
  72.         if (ngx_modules[m]->type != NGX_HTTP_MODULE) {
  73.             continue;
  74.         }

  76.         module = ngx_modules[m]->ctx;
  77.         mi = ngx_modules[m]->ctx_index;

  79.         if (module->create_main_conf) {
  80.             ctx->main_conf[mi] = module->create_main_conf(cf);
  81.             if (ctx->main_conf[mi] == NULL) {
  82.                 return NGX_CONF_ERROR;
  83.             }
  84.         }

  86.         if (module->create_srv_conf) {
  87.             ctx->srv_conf[mi] = module->create_srv_conf(cf);
  88.             if (ctx->srv_conf[mi] == NULL) {
  89.                 return NGX_CONF_ERROR;
  90.             }
  91.         }

  93.         if (module->create_loc_conf) {
  94.             ctx->loc_conf[mi] = module->create_loc_conf(cf);
  95.             if (ctx->loc_conf[mi] == NULL) {
  96.                 return NGX_CONF_ERROR;
  97.             }
  98.         }
  99.     }

  101.     pcf = *cf;
  102.     cf->ctx = ctx;

  104.     for (m = 0; ngx_modules[m]; m++) {
  105.         if (ngx_modules[m]->type != NGX_HTTP_MODULE) {
  106.             continue;
  107.         }

  109.         module = ngx_modules[m]->ctx;

  111.         if (module->preconfiguration) {
  112.             if (module->preconfiguration(cf) != NGX_OK) {
  113.                 return NGX_CONF_ERROR;
  114.             }
  115.         }
  116.     }

  118.     /* parse inside the http{} block */

  120.     cf->module_type = NGX_HTTP_MODULE;
  121.     cf->cmd_type = NGX_HTTP_MAIN_CONF;
  122.     rv = ngx_conf_parse(cf, NULL);

  124.     if (rv != NGX_CONF_OK) {
  125.         goto failed;
  126.     }

  128.     /*
  129.      * init http{} main_conf's, merge the server{}s' srv_conf's
  130.      * and its location{}s' loc_conf's
  131.      */

  133.     cmcf = ctx->main_conf[ngx_http_core_module.ctx_index];
  134.     cscfp = cmcf->servers.elts;

  136.     for (m = 0; ngx_modules[m]; m++) {
  137.         if (ngx_modules[m]->type != NGX_HTTP_MODULE) {
  138.             continue;
  139.         }

  141.         module = ngx_modules[m]->ctx;
  142.         mi = ngx_modules[m]->ctx_index;

  144.         /* init http{} main_conf's */

  146.         if (module->init_main_conf) {
  147.             rv = module->init_main_conf(cf, ctx->main_conf[mi]);
  148.             if (rv != NGX_CONF_OK) {
  149.                 goto failed;
  150.             }
  151.         }

  153.         rv = ngx_http_merge_servers(cf, cmcf, module, mi);
  154.         if (rv != NGX_CONF_OK) {
  155.             goto failed;
  156.         }
  157.     }


  160.     /* create location trees */

  162.     for (s = 0; s < cmcf->servers.nelts; s++) {

  164.         clcf = cscfp[s]->ctx->loc_conf[ngx_http_core_module.ctx_index];

  166.         if (ngx_http_init_locations(cf, cscfp[s], clcf) != NGX_OK) {
  167.             return NGX_CONF_ERROR;
  168.         }

  170.         if (ngx_http_init_static_location_trees(cf, clcf) != NGX_OK) {
  171.             return NGX_CONF_ERROR;
  172.         }
  173.     }


  176.     if (ngx_http_init_phases(cf, cmcf) != NGX_OK) {
  177.         return NGX_CONF_ERROR;
  178.     }

  180.     if (ngx_http_init_headers_in_hash(cf, cmcf) != NGX_OK) {
  181.         return NGX_CONF_ERROR;
  182.     }


  185.     for (m = 0; ngx_modules[m]; m++) {
  186.         if (ngx_modules[m]->type != NGX_HTTP_MODULE) {
  187.             continue;
  188.         }

  190.         module = ngx_modules[m]->ctx;

  192.         if (module->postconfiguration) {
  193.             if (module->postconfiguration(cf) != NGX_OK) {
  194.                 return NGX_CONF_ERROR;
  195.             }
  196.         }
  197.     }

  199.     if (ngx_http_variables_init_vars(cf) != NGX_OK) {
  200.         return NGX_CONF_ERROR;
  201.     }

  203.     /*
  204.      * http{}'s cf->ctx was needed while the configuration merging
  205.      * and in postconfiguration process
  206.      */

  208.     *cf = pcf;


  211.     if (ngx_http_init_phase_handlers(cf, cmcf) != NGX_OK) {
  212.         return NGX_CONF_ERROR;
  213.     }


  216.     /* optimize the lists of ports, addresses and server names */

  218.     if (ngx_http_optimize_servers(cf, cmcf, cmcf->ports) != NGX_OK) {
  219.         return NGX_CONF_ERROR;
  220.     }

  222.     return NGX_CONF_OK;

  224. failed:

  226.     *cf = pcf;

  228.     return rv;
  229. }

 五、解析event block模块


点击(此处)折叠或打开

  1. static char *
  2. ngx_events_block(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
  3. {
  4.     char *rv;
  5.     void ***ctx;
  6.     ngx_uint_t i;
  7.     ngx_conf_t pcf;
  8.     ngx_event_module_t *m;

  10.     if (*(void **) conf) {
  11.         return "is duplicate";
  12.     }

  14.     /* count the number of the event modules and set up their indices */

  16.     ngx_event_max_module = 0;
  17.     for (i = 0; ngx_modules[i]; i++) {
  18.         if (ngx_modules[i]->type != NGX_EVENT_MODULE) {
  19.             continue;
  20.         }

  22.         ngx_modules[i]->ctx_index = ngx_event_max_module++;
  23.     }
  24.     
        //为了和http保持一致，(即4级别 void **** 指针)
  25.     ctx = ngx_pcalloc(cf->pool, sizeof(void *));
  26.     if (ctx == NULL) {
  27.         return NGX_CONF_ERROR;
  28.     }

  30.     *ctx = ngx_pcalloc(cf->pool, ngx_event_max_module * sizeof(void *));
  31.     if (*ctx == NULL) {
  32.         return NGX_CONF_ERROR;
  33.     }

  35.     *(void **) conf = ctx;

  37.     for (i = 0; ngx_modules[i]; i++) {
  38.         if (ngx_modules[i]->type != NGX_EVENT_MODULE) {
  39.             continue;
  40.         }

  42.         m = ngx_modules[i]->ctx;

  44.         if (m->create_conf) {
  45.             (*ctx)[ngx_modules[i]->ctx_index] = m->create_conf(cf->cycle);
  46.             if ((*ctx)[ngx_modules[i]->ctx_index] == NULL) {
  47.                 return NGX_CONF_ERROR;
  48.             }
  49.         }
  50.     }

  52.     pcf = *cf;
  53.     cf->ctx = ctx;
  54.     cf->module_type = NGX_EVENT_MODULE;
  55.     cf->cmd_type = NGX_EVENT_CONF;

  57.     rv = ngx_conf_parse(cf, NULL);

  59.     *cf = pcf;

  61.     if (rv != NGX_CONF_OK)
  62.         return rv;

  64.     for (i = 0; ngx_modules[i]; i++) {
  65.         if (ngx_modules[i]->type != NGX_EVENT_MODULE) {
  66.             continue;
  67.         }

  69.         m = ngx_modules[i]->ctx;

  71.         if (m->init_conf) {
  72.             rv = m->init_conf(cf->cycle, (*ctx)[ngx_modules[i]->ctx_index]);
  73.             if (rv != NGX_CONF_OK) {
  74.                 return rv;
  75.             }
  76.         }
  77.     }

  79.     return NGX_CONF_OK;
  80. }



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