Nginx中发送udp请求

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

1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162636465666768697071727374

ngx_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:

ngx_resolver_send_query

1234567891011121314151617181920212223242526272829303132333435363738394041424344

static ngx_int_tngx_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

123456789101112131415161718192021222324252627282930313233

static voidngx_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:

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

123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253

#include <ngx_config.h>#include <ngx_core.h>#include <ngx_http.h>#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 voidngx_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 voidngx_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_tngx_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;}