Nginx 深度学习

/* 
 * 配置文件解析主函数
 * cf: 配置解析上下文
 * filename: 配置文件路径 (可选，NULL 表示使用默认)
 */
char *
ngx_conf_parse(ngx_conf_t *cf, ngx_str_t *filename)
{
    u_char      *p;
    char        *rv;
    ngx_int_t    rc;
    ngx_buf_t   *buf;
    ngx_str_t    s;
    ngx_conf_file_t *conf_file;

    /* 如果是首次解析，打开配置文件 */
    if (filename) {
        cf->conf_file->file = ngx_open_file(filename->data, ...);
        if (cf->conf_file->file == NGX_INVALID_FILE) {
            return NGX_CONF_ERROR;
        }
    }

    /* 主解析循环：逐行读取配置文件 */
    for ( ;; ) {
        /* 读取一行配置 */
        rc = ngx_conf_read_token(cf);

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

        /* 解析完成 */
        if (rc == NGX_DONE) {
            return NGX_CONF_OK;
        }

        /* 处理解析到的指令 */
        rc = ngx_conf_handler(cf, last);

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

static ngx_int_t
ngx_conf_handler(ngx_conf_t *cf, ngx_int_t last)
{
    char           *rv;
    void           *conf, **confp;
    ngx_uint_t      i, found;
    ngx_cmd_t      *cmd;

    found = 0;

    /* 遍历所有模块的命令，查找匹配的指令 */
    for (i = 0; cf->cycle->modules[i]; i++) {
        cmd = cf->cycle->modules[i]->commands;
        if (cmd == NULL) {
            continue;
        }

        for ( ; cmd->name.len; cmd++) {
            /* 比较指令名称 */
            if (cf->args->elts[0].len != cmd->name.len) {
                continue;
            }

            if (ngx_strcmp(cf->args->elts[0].data, cmd->name.data) != 0) {
                continue;
            }

            found = 1;
            break;
        }

        if (found) {
            break;
        }
    }

    /* 调用找到的命令处理函数 */
    rv = cmd->set(cmd, conf, confp, cf->args);

    return (rv == NGX_CONF_OK) ? NGX_OK : NGX_ERROR;
}

/* 
 * 处理 location 块配置
 * 当解析到 location /xxx { ... } 时调用
 */
static char *
ngx_http_core_location(ngx_conf_t *cf, ngx_cmd_t *cmd, void *conf)
{
    ngx_http_core_srv_conf_t  *cscf;
    ngx_http_core_loc_conf_t  *clcf, *alcf;

    cscf = ngx_http_conf_get_module_srv_conf(cf, ngx_http_core_module);

    /* 创建 location 配置结构 */
    clcf = ngx_pcalloc(cf->pool, sizeof(ngx_http_core_loc_conf_t));
    
    /* 解析 location 修饰符和路径 */
    if (ngx_strcmp(value[1].data, "=") == 0) {
        clcf->name = value[2];
        clcf->exact_match = 1;
    } else if (ngx_strcmp(value[1].data, "~") == 0) {
        clcf->name = value[2];
        clcf->regex = 1;
    } else {
        clcf->name = value[1];
    }

    /* 将 location 添加到 server 的 location 列表 */
    if (cscf->locations == NULL) {
        cscf->locations = ngx_array_create(cf->pool, 1, 
                                           sizeof(ngx_http_core_loc_conf_t *));
    }
    
    clcfp = ngx_array_push(cscf->locations);
    *clcfp = clcf;

    /* 递归解析 location 块内的配置 */
    rv = ngx_conf_parse(cf, NULL);

    return rv;
}

/* 
 * 查找配置 - 第 3 阶段
 * 根据请求 URI 找到对应的 location 配置
 */
static void
ngx_http_core_find_config_phase(ngx_http_request_t *r,
    ngx_http_phase_handler_t *ph)
{
    u_char                    *p;
    size_t                     len;
    ngx_http_core_loc_conf_t  *clcf;

    r->content_handler = NULL;
    r->uri_changed = 0;

    /* 核心：根据 URI 查找匹配的 location */
    clcf = ngx_http_core_find_location(r);

    r->loc_conf = clcf->loc_conf;

    /* 检查请求方法是否允许 */
    if ((r->method & clcf->limit_except) == 0) {
        r->main->count++;
        ngx_http_internal_redirect(r, clcf->name, NULL);
        return;
    }

    /* 设置内容处理 handler */
    r->content_handler = clcf->handler;

    ph++;
    r->phase_handler = ph - r->phase_engine.handlers;
    r->write_event_handler(r);
}

/* 
 * 内容生成阶段 - 第 10 阶段
 * 调用 location 配置中设置的 handler 生成响应
 */
static void
ngx_http_core_content_phase(ngx_http_request_t *r,
    ngx_http_phase_handler_t *ph)
{
    size_t     root;
    ngx_int_t  rc;
    ngx_http_core_loc_conf_t  *clcf;

    clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module);

    /* 如果 location 设置了 handler，直接调用 */
    if (r->content_handler) {
        r->write_event_handler = ngx_http_request_empty_handler;
        rc = r->content_handler(r);
        return;
    }

    /* 没有 handler 时，尝试作为静态文件处理 */
    if (clcf->root.len == 0) {
        ngx_http_finalize_request(r, NGX_HTTP_NOT_FOUND);
        return;
    }

    /* 拼接文件路径并返回文件内容 */
    rc = ngx_http_map_uri_to_path(r, &path, &root, 0);
    if (rc == NGX_ERROR) {
        ngx_http_finalize_request(r, NGX_HTTP_INTERNAL_SERVER_ERROR);
        return;
    }

    ngx_http_finalize_request(r, ngx_http_static_handler(r));
}

# nginx.conf
http {
    server {
        listen 80;
        server_name example.com;
        
        # location 1: 静态文件
        location /static/ {
            root /var/www;
        }
        
        # location 2: 反向代理
        location /api/ {
            proxy_pass http://backend:8080;
        }
        
        # location 3: 精确匹配
        location = /health {
            return 200 "OK";
        }
    }
}