Nginx中发送udp请求
http://blog.aka-cool.net/blog/2014/02/24/udp-in-nginx/
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.cngx_resolver_t *
ngx_resolver_create(ngx_conf_t *cf, ngx_str_t *names, ngx_uint_t n)
{
ngx_str_t s;
ngx_url_t u;
ngx_uint_t i, j;
ngx_resolver_t *r;
ngx_pool_cleanup_t *cln;
ngx_udp_connection_t *uc;
/* 设置回收函数 */
cln = ngx_pool_cleanup_add(cf->pool, 0);
if (cln == NULL) {
return NULL;
}
cln->handler = ngx_resolver_cleanup;
r = ngx_calloc(sizeof(ngx_resolver_t), cf->log);
if (r == NULL) {
return NULL;
}
cln->data = r;
/*
省略很多代码, 初始化红黑树以及队列
*/
for (i = 0; i < n; i++) {
if (ngx_strncmp(names[i].data, "valid=", 6) == 0) {
/*
省略valid参数的设置
*/
}
/* 进入正题 */
ngx_memzero(&u, sizeof(ngx_url_t));
u.url = names[i];
u.default_port = 53;
/* ngx_parse_url用于解析url, 获取ip, port, 地址等信息 */
if (ngx_parse_url(cf->pool, &u) != NGX_OK) {
if (u.err) {
ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
"%s in resolver \"%V\"",
u.err, &u.url);
}
return NULL;
}
uc = ngx_array_push_n(&r->udp_connections, u.naddrs);
if (uc == NULL) {
return NULL;
}
/* 设置各个ngx_udp_connection_t */
ngx_memzero(uc, u.naddrs * sizeof(ngx_udp_connection_t));
for (j = 0; j < u.naddrs; j++) {
/* 看上去只需要设置这几个值;) */
uc[j].sockaddr = u.addrs[j].sockaddr;
uc[j].socklen = u.addrs[j].socklen;
uc[j].server = u.addrs[j].name;
}
}
return r;
} 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:
static ngx_int_t
ngx_resolver_send_query(ngx_resolver_t *r, ngx_resolver_node_t *rn)
{
ssize_t n;
ngx_udp_connection_t *uc;
uc = r->udp_connections.elts;
uc = &uc[r->last_connection++];
if (r->last_connection == r->udp_connections.nelts) {
r->last_connection = 0;
}
if (uc->connection == NULL) {
uc->log = *r->log;
uc->log.handler = ngx_resolver_log_error;
uc->log.data = uc;
uc->log.action = "resolving";
/* 进行连接 */
if (ngx_udp_connect(uc) != NGX_OK) {
return NGX_ERROR;
}
uc->connection->data = r;
uc->connection->read->handler = ngx_resolver_read_response;
uc->connection->read->resolver = 1;
}
/* 发送数据 */
n = ngx_send(uc->connection, rn->query, rn->qlen);
if (n == -1) {
return NGX_ERROR;
}
if ((size_t) n != (size_t) rn->qlen) {
ngx_log_error(NGX_LOG_CRIT, &uc->log, 0, "send() incomplete");
return NGX_ERROR;
}
return NGX_OK;
}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
static void
ngx_resolver_cleanup(void *data)
{
ngx_resolver_t *r = data;
ngx_uint_t i;
ngx_udp_connection_t *uc;
if (r) {
ngx_log_debug0(NGX_LOG_DEBUG_CORE, ngx_cycle->log, 0,
"cleanup resolver");
ngx_resolver_cleanup_tree(r, &r->name_rbtree);
ngx_resolver_cleanup_tree(r, &r->addr_rbtree);
if (r->event) {
ngx_free(r->event);
}
uc = r->udp_connections.elts;
/* 关闭每一个建立的连接 */
for (i = 0; i < r->udp_connections.nelts; i++) {
if (uc[i].connection) {
ngx_close_connection(uc[i].connection);
}
}
ngx_free(r);
}
}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:
- 初始化ngx_udp_connection_t类型的变量(通常会用到ngx_parse_url)
- 使用ngx_udp_connect进行连接
- 使用ngx_send进行数据发送
- 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
#include
#include
#include
#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,
&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->args->elts;
ngx_conf_log_error(NGX_LOG_INFO, cf, 0, "play: %s", value[1].data);
plcf->enable = 0;
if (ngx_strncmp(value[1].data, "on", 2) == 0) {
clcf->handler = ngx_http_play_handler;
plcf->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(&u, sizeof(ngx_url_t));
value = cf->args->elts;
/* resolve url */
u.url = value[1];
u.default_port = 12345;
u.no_resolve = 0;
if (ngx_parse_url(cf->pool, &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->play_udp_uc = ngx_pcalloc(cf->pool, sizeof(ngx_udp_connection_t));
uc = plcf->play_udp_uc;
if (uc == NULL) {
return NGX_CONF_ERROR;
}
/* implement udp connection */
uc->sockaddr = u.addrs[0].sockaddr;
uc->socklen = u.addrs[0].socklen;
uc->server = u.addrs[0].name;
uc->log = cf->cycle->new_log;
/* implement clean handler */
cln = ngx_pool_cleanup_add(cf->pool, 0);
if (cln == NULL) {
return NGX_CONF_ERROR;
}
cln->data = uc;
cln->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->log, 0,
"cleanup http_upstream_keepalive_fluentd");
if (uc->connection) {
ngx_close_connection(uc->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->connection == NULL) {
if (ngx_udp_connect(uc) != NGX_OK) {
return;
}
uc->connection->data = NULL;
uc->connection->read->handler = ngx_http_play_dummy_handler;
uc->connection->read->resolver = 1;
}
ngx_send(uc->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(&r->headers_out.content_type, "text/html");
b = ngx_pcalloc(r->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->play_udp_uc);
b->pos = (u_char *)"send";
b->last = b->pos + 4;
///////////////////////////////////////////////////////////////////////////////////////////////
b->memory = 1;
b->last_buf = 1;
r->headers_out.status = NGX_HTTP_OK;
//r->headers_out.content_length_n = var.len;
rc = ngx_http_send_header(r);
return ngx_http_output_filter(r, &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->pool, sizeof(ngx_http_play_loc_conf_t));
if (plcf == NULL) {
return NULL;
}
return plcf;
} 使用nc监听一下发现可以成功~