Nginx

Nginx的http模块代码分析

1、代码框架

http模块主要代码放在ngx_http.c这个文件中，接下来我们就来分析下相关代码

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static char *ngx_http_block(ngx_conf_t *cf, ngx_command_t *cmd, void *conf);
static ngx_int_t ngx_http_init_phases(ngx_conf_t *cf,
    ngx_http_core_main_conf_t *cmcf);
static ngx_int_t ngx_http_init_headers_in_hash(ngx_conf_t *cf,
    ngx_http_core_main_conf_t *cmcf);
static ngx_int_t ngx_http_init_phase_handlers(ngx_conf_t *cf,
    ngx_http_core_main_conf_t *cmcf);

static ngx_int_t ngx_http_add_addresses(ngx_conf_t *cf,
    ngx_http_core_srv_conf_t *cscf, ngx_http_conf_port_t *port,
    ngx_http_listen_opt_t *lsopt);
static ngx_int_t ngx_http_add_address(ngx_conf_t *cf,
    ngx_http_core_srv_conf_t *cscf, ngx_http_conf_port_t *port,
    ngx_http_listen_opt_t *lsopt);
static ngx_int_t ngx_http_add_server(ngx_conf_t *cf,
    ngx_http_core_srv_conf_t *cscf, ngx_http_conf_addr_t *addr);

static char *ngx_http_merge_servers(ngx_conf_t *cf,
    ngx_http_core_main_conf_t *cmcf, ngx_http_module_t *module,
    ngx_uint_t ctx_index);
static char *ngx_http_merge_locations(ngx_conf_t *cf,
    ngx_queue_t *locations, void **loc_conf, ngx_http_module_t *module,
    ngx_uint_t ctx_index);
static ngx_int_t ngx_http_init_locations(ngx_conf_t *cf,
    ngx_http_core_srv_conf_t *cscf, ngx_http_core_loc_conf_t *pclcf);
static ngx_int_t ngx_http_init_static_location_trees(ngx_conf_t *cf,
    ngx_http_core_loc_conf_t *pclcf);
static ngx_int_t ngx_http_cmp_locations(const ngx_queue_t *one,
    const ngx_queue_t *two);
static ngx_int_t ngx_http_join_exact_locations(ngx_conf_t *cf,
    ngx_queue_t *locations);
static void ngx_http_create_locations_list(ngx_queue_t *locations,
    ngx_queue_t *q);
static ngx_http_location_tree_node_t *
    ngx_http_create_locations_tree(ngx_conf_t *cf, ngx_queue_t *locations,
    size_t prefix);

static ngx_int_t ngx_http_optimize_servers(ngx_conf_t *cf,
    ngx_http_core_main_conf_t *cmcf, ngx_array_t *ports);
static ngx_int_t ngx_http_server_names(ngx_conf_t *cf,
    ngx_http_core_main_conf_t *cmcf, ngx_http_conf_addr_t *addr);
static ngx_int_t ngx_http_cmp_conf_addrs(const void *one, const void *two);
static int ngx_libc_cdecl ngx_http_cmp_dns_wildcards(const void *one,
    const void *two);

static ngx_int_t ngx_http_init_listening(ngx_conf_t *cf,
    ngx_http_conf_port_t *port);
static ngx_listening_t *ngx_http_add_listening(ngx_conf_t *cf,
    ngx_http_conf_addr_t *addr);
static ngx_int_t ngx_http_add_addrs(ngx_conf_t *cf, ngx_http_port_t *hport,
    ngx_http_conf_addr_t *addr);
#if (NGX_HAVE_INET6)
static ngx_int_t ngx_http_add_addrs6(ngx_conf_t *cf, ngx_http_port_t *hport,
    ngx_http_conf_addr_t *addr);
#endif

在ngx_http.c文件最前面这部分代码全部是函数声明，接下来看下http模块配置，指令设置、函数指针以及模块结构初始化

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ngx_uint_t   ngx_http_max_module;


ngx_http_output_header_filter_pt  ngx_http_top_header_filter;
ngx_http_output_body_filter_pt    ngx_http_top_body_filter;
ngx_http_request_body_filter_pt   ngx_http_top_request_body_filter;

ngx_str_t  ngx_http_html_default_types[] = {
    ngx_string("text/html"),
    ngx_null_string
};

// http指令定义
static ngx_command_t  ngx_http_commands[] = {

    { ngx_string("http"),
      NGX_MAIN_CONF|NGX_CONF_BLOCK|NGX_CONF_NOARGS,
      ngx_http_block,
      0,
      0,
      NULL },

      ngx_null_command
};

//核心模块上下文
static ngx_core_module_t  ngx_http_module_ctx = {
    ngx_string("http"),
    NULL,
    NULL
};

//http模块定义
ngx_module_t  ngx_http_module = {
    NGX_MODULE_V1,
    &ngx_http_module_ctx,                  /* module context */
    ngx_http_commands,                     /* module directives */
    NGX_CORE_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
};

接下来看下http块解析函数，ngx_http_block函数实现

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static char *
ngx_http_block(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
    char                        *rv;
    ngx_uint_t                   mi, m, s;
    ngx_conf_t                   pcf;
    ngx_http_module_t           *module;
    ngx_http_conf_ctx_t         *ctx;
    ngx_http_core_loc_conf_t    *clcf;
    ngx_http_core_srv_conf_t   **cscfp;
    ngx_http_core_main_conf_t   *cmcf;

    // 判断是否重复配置
    if (*(ngx_http_conf_ctx_t **) conf) {
        return "is duplicate";
    }

    /* the main http context */

    // 申请保存上下文的内存
    ctx = ngx_pcalloc(cf->pool, sizeof(ngx_http_conf_ctx_t));
    if (ctx == NULL) {
        return NGX_CONF_ERROR;
    }

    *(ngx_http_conf_ctx_t **) conf = ctx;


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

    ngx_http_max_module = ngx_count_modules(cf->cycle, NGX_HTTP_MODULE);


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

    ctx->main_conf = ngx_pcalloc(cf->pool,
                                 sizeof(void *) * ngx_http_max_module);
    if (ctx->main_conf == NULL) {
        return NGX_CONF_ERROR;
    }


    /*
     * the http null srv_conf context, it is used to merge
     * the server{}s' srv_conf's
     */

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


    /*
     * the http null loc_conf context, it is used to merge
     * the server{}s' loc_conf's
     */

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


    /*
     * create the main_conf's, the null srv_conf's, and the null loc_conf's
     * of the all http modules
     */

    for (m = 0; cf->cycle->modules[m]; m++) {
        // 跳过非http模块
        if (cf->cycle->modules[m]->type != NGX_HTTP_MODULE) {
            continue;
        }

        module = cf->cycle->modules[m]->ctx;
        mi = cf->cycle->modules[m]->ctx_index;

        // 调用每个模块创建main级别conf的函数指针
        if (module->create_main_conf) {
            ctx->main_conf[mi] = module->create_main_conf(cf);
            if (ctx->main_conf[mi] == NULL) {
                return NGX_CONF_ERROR;
            }
        }

        // 调用每个模块创建server级别conf的函数指针
        if (module->create_srv_conf) {
            ctx->srv_conf[mi] = module->create_srv_conf(cf);
            if (ctx->srv_conf[mi] == NULL) {
                return NGX_CONF_ERROR;
            }
        }

        // 调用每个模块创建location级别conf的函数指针
        if (module->create_loc_conf) {
            ctx->loc_conf[mi] = module->create_loc_conf(cf);
            if (ctx->loc_conf[mi] == NULL) {
                return NGX_CONF_ERROR;
            }
        }
    }

    // 保存cf，在解析完配置后会还原
    pcf = *cf;
    // 保存http级别conf
    cf->ctx = ctx;

    for (m = 0; cf->cycle->modules[m]; m++) {
        // 跳过非http模块
        if (cf->cycle->modules[m]->type != NGX_HTTP_MODULE) {
            continue;
        }

        module = cf->cycle->modules[m]->ctx;
        //调用每个模块preconfiguration函数指针，在解析配置前需要做的
        if (module->preconfiguration) {
            if (module->preconfiguration(cf) != NGX_OK) {
                return NGX_CONF_ERROR;
            }
        }
    }

    /* parse inside the http{} block */

    cf->module_type = NGX_HTTP_MODULE;
    cf->cmd_type = NGX_HTTP_MAIN_CONF;
    // 开始解析http块里面的配置
    rv = ngx_conf_parse(cf, NULL);

    if (rv != NGX_CONF_OK) {
        goto failed;
    }

    /*
     * init http{} main_conf's, merge the server{}s' srv_conf's
     * and its location{}s' loc_conf's
     */

    // 取http main级别的conf
    cmcf = ctx->main_conf[ngx_http_core_module.ctx_index];
    cscfp = cmcf->servers.elts;

    // 调用每个http模块初始化main级别配置的函数
    for (m = 0; cf->cycle->modules[m]; m++) {
        // 跳过非http模块
        if (cf->cycle->modules[m]->type != NGX_HTTP_MODULE) {
            continue;
        }

        module = cf->cycle->modules[m]->ctx;
        mi = cf->cycle->modules[m]->ctx_index;

        /* init http{} main_conf's */
        // 调用每个模块init_main_conf函数指针
        if (module->init_main_conf) {
            rv = module->init_main_conf(cf, ctx->main_conf[mi]);
            if (rv != NGX_CONF_OK) {
                goto failed;
            }
        }

        // 合并server级别及location级别配置
        rv = ngx_http_merge_servers(cf, cmcf, module, mi);
        if (rv != NGX_CONF_OK) {
            goto failed;
        }
    }


    /* create location trees */
    // 构造http请求location匹配树
    for (s = 0; s < cmcf->servers.nelts; s++) {

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

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

        // 构造静态location匹配树
        if (ngx_http_init_static_location_trees(cf, clcf) != NGX_OK) {
            return NGX_CONF_ERROR;
        }
    }


    // 初始化各个阶段的array
    if (ngx_http_init_phases(cf, cmcf) != NGX_OK) {
        return NGX_CONF_ERROR;
    }

    // 初始化http请求头headers
    if (ngx_http_init_headers_in_hash(cf, cmcf) != NGX_OK) {
        return NGX_CONF_ERROR;
    }

    // 处理每个http模块postconfiguration
    for (m = 0; cf->cycle->modules[m]; m++) {
        if (cf->cycle->modules[m]->type != NGX_HTTP_MODULE) {
            continue;
        }

        module = cf->cycle->modules[m]->ctx;
        //调用每个模块postconfiguration函数指针，用于处理配置解析完成后的操作
        if (module->postconfiguration) {
            if (module->postconfiguration(cf) != NGX_OK) {
                return NGX_CONF_ERROR;
            }
        }
    }

    // 初始化http变量
    if (ngx_http_variables_init_vars(cf) != NGX_OK) {
        return NGX_CONF_ERROR;
    }

    /*
     * http{}'s cf->ctx was needed while the configuration merging
     * and in postconfiguration process
     */
    // 恢复cf
    *cf = pcf;

    // 初始化http各个阶段handler
    if (ngx_http_init_phase_handlers(cf, cmcf) != NGX_OK) {
        return NGX_CONF_ERROR;
    }


    /* optimize the lists of ports, addresses and server names */
    // 处理相同端口以及server_name
    if (ngx_http_optimize_servers(cf, cmcf, cmcf->ports) != NGX_OK) {
        return NGX_CONF_ERROR;
    }

    return NGX_CONF_OK;

failed:
    // 恢复cf
    *cf = pcf;
    // 返回结果
    return rv;
}

接下来分析ngx_http_optimize_servers函数，此函数用于处理IP+Port相同，不同server_name的情况

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static ngx_int_t
ngx_http_optimize_servers(ngx_conf_t *cf, ngx_http_core_main_conf_t *cmcf,
    ngx_array_t *ports)
{
    ngx_uint_t             p, a;
    ngx_http_conf_port_t  *port;
    ngx_http_conf_addr_t  *addr;

    // 如果没有配置端口，则返回
    if (ports == NULL) {
        return NGX_OK;
    }

    // 遍历已经配置的port列表，
    port = ports->elts;
    for (p = 0; p < ports->nelts; p++) {

        // 将同一个port下挂的addr进行排序
        ngx_sort(port[p].addrs.elts, (size_t) port[p].addrs.nelts,
                 sizeof(ngx_http_conf_addr_t), ngx_http_cmp_conf_addrs);

        /*
         * check whether all name-based servers have the same
         * configuration as a default server for given address:port
         */

        // 如果一个addr下有多个server块，则处理server_name
        addr = port[p].addrs.elts;
        for (a = 0; a < port[p].addrs.nelts; a++) {

            if (addr[a].servers.nelts > 1
#if (NGX_PCRE)
                || addr[a].default_server->captures
#endif
               )
            {
                if (ngx_http_server_names(cf, cmcf, &addr[a]) != NGX_OK) {
                    return NGX_ERROR;
                }
            }
        }

        // 处理listen，从cycle->listening分配元素
        if (ngx_http_init_listening(cf, &port[p]) != NGX_OK) {
            return NGX_ERROR;
        }
    }

    return NGX_OK;
}

  1. 接下来分析ngx_http_server_names函数，这个函数的功能是server_name进行hash处理
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static ngx_int_t
ngx_http_server_names(ngx_conf_t *cf, ngx_http_core_main_conf_t *cmcf,
    ngx_http_conf_addr_t *addr)
{
    ngx_int_t                   rc;
    ngx_uint_t                  n, s;
    ngx_hash_init_t             hash;
    ngx_hash_keys_arrays_t      ha;
    ngx_http_server_name_t     *name;
    ngx_http_core_srv_conf_t  **cscfp;
#if (NGX_PCRE)
    ngx_uint_t                  regex, i;

    regex = 0;
#endif

    // 初始化hash key数组
    ngx_memzero(&ha, sizeof(ngx_hash_keys_arrays_t));

    // 创建初始化hash table所需的内存池
    ha.temp_pool = ngx_create_pool(NGX_DEFAULT_POOL_SIZE, cf->log);
    if (ha.temp_pool == NULL) {
        return NGX_ERROR;
    }

    ha.pool = cf->pool;

    // 初始化hash key
    if (ngx_hash_keys_array_init(&ha, NGX_HASH_LARGE) != NGX_OK) {
        goto failed;
    }

    cscfp = addr->servers.elts;

    // 遍历此地址下的所有server块
    for (s = 0; s < addr->servers.nelts; s++) {

        name = cscfp[s]->server_names.elts;

        for (n = 0; n < cscfp[s]->server_names.nelts; n++) {

#if (NGX_PCRE)
            if (name[n].regex) {
                regex++;
                continue;
            }
#endif

            // 将server_name添加到key中
            rc = ngx_hash_add_key(&ha, &name[n].name, name[n].server,
                                  NGX_HASH_WILDCARD_KEY);

            if (rc == NGX_ERROR) {
                return NGX_ERROR;
            }

            if (rc == NGX_DECLINED) {
                ngx_log_error(NGX_LOG_EMERG, cf->log, 0,
                              "invalid server name or wildcard \"%V\" on %V",
                              &name[n].name, &addr->opt.addr_text);
                return NGX_ERROR;
            }

            // server_name出现冲突
            if (rc == NGX_BUSY) {
                ngx_log_error(NGX_LOG_WARN, cf->log, 0,
                              "conflicting server name \"%V\" on %V, ignored",
                              &name[n].name, &addr->opt.addr_text);
            }
        }
    }

    // 对hash表赋初值
    hash.key = ngx_hash_key_lc;
    hash.max_size = cmcf->server_names_hash_max_size;
    hash.bucket_size = cmcf->server_names_hash_bucket_size;
    hash.name = "server_names_hash";
    hash.pool = cf->pool;

    if (ha.keys.nelts) {
        hash.hash = &addr->hash;
        hash.temp_pool = NULL;

        if (ngx_hash_init(&hash, ha.keys.elts, ha.keys.nelts) != NGX_OK) {
            goto failed;
        }
    }

    // 前缀匹配
    if (ha.dns_wc_head.nelts) {

        ngx_qsort(ha.dns_wc_head.elts, (size_t) ha.dns_wc_head.nelts,
                  sizeof(ngx_hash_key_t), ngx_http_cmp_dns_wildcards);

        hash.hash = NULL;
        hash.temp_pool = ha.temp_pool;

        if (ngx_hash_wildcard_init(&hash, ha.dns_wc_head.elts,
                                   ha.dns_wc_head.nelts)
            != NGX_OK)
        {
            goto failed;
        }

        addr->wc_head = (ngx_hash_wildcard_t *) hash.hash;
    }

    // 后缀匹配
    if (ha.dns_wc_tail.nelts) {

        ngx_qsort(ha.dns_wc_tail.elts, (size_t) ha.dns_wc_tail.nelts,
                  sizeof(ngx_hash_key_t), ngx_http_cmp_dns_wildcards);

        hash.hash = NULL;
        hash.temp_pool = ha.temp_pool;

        if (ngx_hash_wildcard_init(&hash, ha.dns_wc_tail.elts,
                                   ha.dns_wc_tail.nelts)
            != NGX_OK)
        {
            goto failed;
        }

        addr->wc_tail = (ngx_hash_wildcard_t *) hash.hash;
    }

    ngx_destroy_pool(ha.temp_pool);

    // 处理正则
#if (NGX_PCRE)

    if (regex == 0) {
        return NGX_OK;
    }

    addr->nregex = regex;
    addr->regex = ngx_palloc(cf->pool, regex * sizeof(ngx_http_server_name_t));
    if (addr->regex == NULL) {
        return NGX_ERROR;
    }

    i = 0;

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

        name = cscfp[s]->server_names.elts;
        // 遍历server_name，对regex进行处理
        for (n = 0; n < cscfp[s]->server_names.nelts; n++) {
            if (name[n].regex) {
                addr->regex[i++] = name[n];
            }
        }
    }

#endif

    return NGX_OK;

failed:
    // 释放temp_pool
    ngx_destroy_pool(ha.temp_pool);

    return NGX_ERROR;
}

  1. 接下来分析ngx_http_init_listening函数
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static ngx_int_t
ngx_http_init_listening(ngx_conf_t *cf, ngx_http_conf_port_t *port)
{
    ngx_uint_t                 i, last, bind_wildcard;
    ngx_listening_t           *ls;
    ngx_http_port_t           *hport;
    ngx_http_conf_addr_t      *addr;

    addr = port->addrs.elts;
    last = port->addrs.nelts;

    /*
     * If there is a binding to an "*:port" then we need to bind() to
     * the "*:port" only and ignore other implicit bindings.  The bindings
     * have been already sorted: explicit bindings are on the start, then
     * implicit bindings go, and wildcard binding is in the end.
     */

    if (addr[last - 1].opt.wildcard) {
        addr[last - 1].opt.bind = 1;
        bind_wildcard = 1;

    } else {
        bind_wildcard = 0;
    }

    i = 0;

    while (i < last) {

        if (bind_wildcard && !addr[i].opt.bind) {
            i++;
            continue;
        }

        // 从ngx_cycle->listening中push一个ls，跟socket相关的都保存在这里面
        ls = ngx_http_add_listening(cf, &addr[i]);
        if (ls == NULL) {
            return NGX_ERROR;
        }

        // 分配保存地址的内存，在ngx_init_connection中使用
        hport = ngx_pcalloc(cf->pool, sizeof(ngx_http_port_t));
        if (hport == NULL) {
            return NGX_ERROR;
        }

        ls->servers = hport;

        hport->naddrs = i + 1;

        switch (ls->sockaddr->sa_family) {

#if (NGX_HAVE_INET6)
        case AF_INET6:
            if (ngx_http_add_addrs6(cf, hport, addr) != NGX_OK) {
                return NGX_ERROR;
            }
            break;
#endif
        default: /* AF_INET */
            // 将addr中的内容复制到hport中
            if (ngx_http_add_addrs(cf, hport, addr) != NGX_OK) {
                return NGX_ERROR;
            }
            break;
        }

        addr++;
        last--;
    }

    return NGX_OK;
}

  1. 接下来看看ngx_http_add_addrs函数的实现，ngx_http_add_addrs6类似
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static ngx_int_t
ngx_http_add_addrs(ngx_conf_t *cf, ngx_http_port_t *hport,
    ngx_http_conf_addr_t *addr)
{
    ngx_uint_t                 i;
    ngx_http_in_addr_t        *addrs;
    struct sockaddr_in        *sin;
    ngx_http_virtual_names_t  *vn;

    // 申请必要内存，naddrs就是外面计算的这个端口下的ip个数
    hport->addrs = ngx_pcalloc(cf->pool,
                               hport->naddrs * sizeof(ngx_http_in_addr_t));
    if (hport->addrs == NULL) {
        return NGX_ERROR;
    }

    addrs = hport->addrs;

    for (i = 0; i < hport->naddrs; i++) {

        sin = (struct sockaddr_in *) addr[i].opt.sockaddr;
        addrs[i].addr = sin->sin_addr.s_addr;
        addrs[i].conf.default_server = addr[i].default_server;
#if (NGX_HTTP_SSL)
        addrs[i].conf.ssl = addr[i].opt.ssl;
#endif
#if (NGX_HTTP_V2)
        addrs[i].conf.http2 = addr[i].opt.http2;
#endif
        addrs[i].conf.proxy_protocol = addr[i].opt.proxy_protocol;

        // 如果匹配server_name所需的hash桶为空，则不进行下一步操作
        if (addr[i].hash.buckets == NULL
            && (addr[i].wc_head == NULL
                || addr[i].wc_head->hash.buckets == NULL)
            && (addr[i].wc_tail == NULL
                || addr[i].wc_tail->hash.buckets == NULL)
#if (NGX_PCRE)
            && addr[i].nregex == 0
#endif
            )
        {
            continue;
        }

        // 申请保存server_name匹配所需内存
        vn = ngx_palloc(cf->pool, sizeof(ngx_http_virtual_names_t));
        if (vn == NULL) {
            return NGX_ERROR;
        }

        addrs[i].conf.virtual_names = vn;

        // 保存server_name匹配所需的hash值
        vn->names.hash = addr[i].hash;
        vn->names.wc_head = addr[i].wc_head;
        vn->names.wc_tail = addr[i].wc_tail;
#if (NGX_PCRE)
        vn->nregex = addr[i].nregex;
        vn->regex = addr[i].regex;
#endif
    }

    return NGX_OK;
}

  1. 接下来看看函数的实现
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