Nginx中发送udp请求

我就是我 2022-08-02 20:28 253阅读 0赞

## Nginx中发送udp请求 ##

最近简单了解了一下Nginx发送udp请求的过程, 在这里简单记录一下.

主要参考的代码主要有两块, 分别是ngx\_resolver.c以及agentzh的ngx\_lua模块中的udp相关代码(ngx\_http\_lua\_socket\_udp.c). 有兴趣的同学可以看一下.

## 简单分析 ##

首先看一下ngx\_resolver.c这个文件, 主要解决了dns查询的问题, 也就是[resolver][]这个指令. 这个文件长度还是蛮长的, 大概有2000多行, 但是udp部分的代码还是相当简洁的, 主要分为几个步骤: 初始化, 连接, 发送以及回收.

初始化的代码:

ngx\_resolver.c

这里主要就是根据配置文件来初始化`ngx_udp_connection_t`类型的变量. 接下来是连接和发送请求:

ngx\_resolver\_send\_query

主要是使用了ngx\_udp\_connect和ngx\_send这两个函数. 用起来还是相当方便的, 里面的实现有兴趣的同学可以看一下. 最后就是关闭连接:

ngx\_resolver\_cleanup

主要是调用了ngx\_close\_connection这个函数. 通过以上操作就完成了一次udp数据的发送. ngx\_lua当中也基本是这个步骤.

总结下就是:

1.  初始化ngx\_udp\_connection\_t类型的变量(通常会用到ngx\_parse\_url)
2.  使用ngx\_udp\_connect进行连接
3.  使用ngx\_send进行数据发送
4.  关闭连接, 可以在数据回收的回调中进行关闭

## 自己写一个试试 ##

看明白了基本步骤, 自己验证一下, 写一个的对应的简单handler模块. 在配置文件中设置udp\_address来设置要发送的地址, nginx接受到请求之后即向这个地址发送信息.

ngx\_resolver\_cleanup

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</pre> </td> 
 <td style="margin:0px; padding:0px 0px 0px 14px; width:792px; overflow-x:auto"> <pre style="margin-top:0px; margin-bottom:0px; padding:0px; border:none; font-family:Menlo,Monaco,'Andale Mono','lucida console','Courier New',monospace; line-height:1.5; overflow-x:auto; background:none"><code style="margin:0px; padding:0px; border:none; font-family:Menlo,Monaco,'Andale Mono','lucida console','Courier New',monospace; font-size:0.9em; color:rgb(147,161,161)!important; font-style:italic!important; background:none">#include &lt;ngx_config.h&gt; #include &lt;ngx_core.h&gt; #include &lt;ngx_http.h&gt; #include "ddebug.h" typedef struct { ngx_flag_t enable; ngx_udp_connection_t *play_udp_uc; } ngx_http_play_loc_conf_t; ngx_int_t ngx_udp_connect(ngx_udp_connection_t *uc); static void *ngx_http_play_create_loc_conf(ngx_conf_t *cf); static char *ngx_conf_play(ngx_conf_t *cf, ngx_command_t *cmd, void *conf); static void ngx_http_upstream_play_cleanup(void *data); static char *ngx_conf_set_udp_addr(ngx_conf_t *cf, ngx_command_t *cmd, void *conf); static ngx_int_t ngx_http_play_handler(ngx_http_request_t *r); static ngx_command_t ngx_http_play_commands[] = { { ngx_string("play"), NGX_HTTP_LOC_CONF | NGX_CONF_TAKE1, ngx_conf_play, NGX_HTTP_LOC_CONF_OFFSET, 0, NULL }, { ngx_string("udp_address"), NGX_HTTP_LOC_CONF | NGX_CONF_TAKE1, ngx_conf_set_udp_addr, NGX_HTTP_LOC_CONF_OFFSET, 0, NULL }, ngx_null_command }; static ngx_http_module_t ngx_http_play_module_ctx = { NULL, /* preconfiguration */ //ngx_http_play_init, /* postconfiguration */ NULL, /* postconfiguration */ NULL, /* create main configuration */ NULL, /* init main configuration */ NULL, /* create server configuration */ NULL, /* merge server configuration */ ngx_http_play_create_loc_conf, /* create location configuration */ NULL /* merge location configuration */ }; ngx_module_t ngx_http_play_module = { NGX_MODULE_V1, &amp;ngx_http_play_module_ctx, /* module context */ ngx_http_play_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 char * ngx_conf_play(ngx_conf_t *cf, ngx_command_t *cmd, void *conf) { ngx_http_play_loc_conf_t *plcf; ngx_http_core_loc_conf_t *clcf; ngx_str_t *value; clcf = ngx_http_conf_get_module_loc_conf(cf, ngx_http_core_module); plcf = conf; value = cf-&gt;args-&gt;elts; ngx_conf_log_error(NGX_LOG_INFO, cf, 0, "play: %s", value[1].data); plcf-&gt;enable = 0; if (ngx_strncmp(value[1].data, "on", 2) == 0) { clcf-&gt;handler = ngx_http_play_handler; plcf-&gt;enable = 1; } return NGX_CONF_OK; } static char * ngx_conf_set_udp_addr(ngx_conf_t *cf, ngx_command_t *cmd, void *conf) { ngx_http_play_loc_conf_t *plcf; ngx_str_t *value; ngx_url_t u; ngx_pool_cleanup_t *cln; ngx_udp_connection_t *uc; plcf = conf; ngx_memzero(&amp;u, sizeof(ngx_url_t)); value = cf-&gt;args-&gt;elts; /* resolve url */ u.url = value[1]; u.default_port = 12345; u.no_resolve = 0; if (ngx_parse_url(cf-&gt;pool, &amp;u) != NGX_OK) { ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, "parse udp addr failed, %s", value[1].data); return NGX_CONF_ERROR; } /* init udp connection */ plcf-&gt;play_udp_uc = ngx_pcalloc(cf-&gt;pool, sizeof(ngx_udp_connection_t)); uc = plcf-&gt;play_udp_uc; if (uc == NULL) { return NGX_CONF_ERROR; } /* implement udp connection */ uc-&gt;sockaddr = u.addrs[0].sockaddr; uc-&gt;socklen = u.addrs[0].socklen; uc-&gt;server = u.addrs[0].name; uc-&gt;log = cf-&gt;cycle-&gt;new_log; /* implement clean handler */ cln = ngx_pool_cleanup_add(cf-&gt;pool, 0); if (cln == NULL) { return NGX_CONF_ERROR; } cln-&gt;data = uc; cln-&gt;handler = ngx_http_upstream_play_cleanup; // set the cleanup handler return NGX_OK; } static void ngx_http_upstream_play_cleanup(void *data) { ngx_udp_connection_t *uc = data; ngx_log_debug0(NGX_LOG_DEBUG_CORE, ngx_cycle-&gt;log, 0, "cleanup http_upstream_keepalive_fluentd"); if (uc-&gt;connection) { ngx_close_connection(uc-&gt;connection); } } static void ngx_http_play_dummy_handler(ngx_event_t *ev) { /* just empty */ } static void ngx_http_play_send_udp(ngx_http_request_t *r, ngx_udp_connection_t *uc) { if (uc-&gt;connection == NULL) { if (ngx_udp_connect(uc) != NGX_OK) { return; } uc-&gt;connection-&gt;data = NULL; uc-&gt;connection-&gt;read-&gt;handler = ngx_http_play_dummy_handler; uc-&gt;connection-&gt;read-&gt;resolver = 1; } ngx_send(uc-&gt;connection, (u_char*)"hello", 5); return; } /* the main function */ static ngx_int_t ngx_http_play_handler(ngx_http_request_t *r) { ngx_int_t rc; ngx_buf_t *b; ngx_chain_t out; ngx_variable_value_t *var; ngx_http_play_loc_conf_t *plcf; plcf = ngx_http_get_module_loc_conf(r, ngx_http_play_module); /* here we go ;) */ rc = ngx_http_discard_request_body(r); if (rc != NGX_OK) { return rc; } ngx_str_set(&amp;r-&gt;headers_out.content_type, "text/html"); b = ngx_pcalloc(r-&gt;pool, sizeof(ngx_buf_t)); if (b == NULL) { return NGX_HTTP_INTERNAL_SERVER_ERROR; } out.buf = b; out.next = NULL; /* * * I want to change here ;) * * */ ngx_http_play_send_udp(r, plcf-&gt;play_udp_uc); b-&gt;pos = (u_char *)"send"; b-&gt;last = b-&gt;pos + 4; /// b-&gt;memory = 1; b-&gt;last_buf = 1; r-&gt;headers_out.status = NGX_HTTP_OK; //r-&gt;headers_out.content_length_n = var.len; rc = ngx_http_send_header(r); return ngx_http_output_filter(r, &amp;out); } static void * ngx_http_play_create_loc_conf(ngx_conf_t *cf) { ngx_http_play_loc_conf_t *plcf = NULL; plcf = ngx_pcalloc(cf-&gt;pool, sizeof(ngx_http_play_loc_conf_t)); if (plcf == NULL) { return NULL; } return plcf; }</code></pre> </td> 
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[resolver]: http://nginx.org/en/docs/http/ngx_http_core_module.html#resolver