【原创】libevent练手之--简单的反向代理，非阻塞，能超越65535连接上限

背景信息--- 单机tcp连接上限

      当建立一个tcp连接时，客户端被分配（或者你可以指定）一个端口，范围在 /proc/sys/net/ipv4/ip_local_port_range里 . 假如你手工指定也没什么问题， 用临时端口我们会超出界限。

我设置这个范围在“1024 65535″之间 – 这就意味这有65535-1024 = 64511个端口可用。也即同时只能反向代理这么多个请求。

 

但，可以

 

弄多个新的IP地址, 每个让他建立62000个连接 – 以17个IP为例，共1,054,000 个连接.

$ for i in `seq 1 17`; do echo sudo ifconfig eth0:$i 10.0.0.$i up ; done

假如你现在运行ifconfig 你应该看到你的虚拟往里接口: eth0:1, eth0:2 … eth0:17, 每个有不同的IP地址。很显然，你应该选择一个你所需要的地址空间。

 

 

然后， 使用libevent库的函数

   //可以为每个连接设置本地IP，一台机可以多个IP，就可超过65535－1024个连接

    evhttp_connection_set_local_address(evhttp_connection, &local_addr);

 

 

代码：

 

要先安装libevent

编译项：

 

gcc httpproxy.c -L/usr/local/libevent-1.4.13-stable/lib  -levent -o"httpproxy" 

 

/********************** * [e-mail] * [e-mail] * 2010-11-23 * 简单的http反向代理 * *******************/#include<stdio.h>#include<stdlib.h>#include<sys/queue.h>#include<event.h>#include<evhttp.h>char *proxy_host = "10.20.187.231";unsigned int proxy_port = 80;int proxy_timeout_in_secs = 60;// called per chunk receivedvoid chunkcb(struct evhttp_request * req, void * arg) {struct evhttp_request *response = (struct evhttp_request *)arg;evbuffer_add_buffer(((struct evhttp_request *)arg)->output_buffer , req->input_buffer);if (++response->chunked == req->chunked){evhttp_send_reply(response, req->response_code, req->response_code_line, req->input_buffer);return;}}// gets called when request completesvoid reqcb(struct evhttp_request * req, void * arg) {struct evhttp_request *response = (struct evhttp_request*)arg;if(!req){fprintf(stdout, "http close.");evhttp_send_reply(response, 504, "Bad Gateway.", NULL);return;}if (response->chunked)return;struct evkeyval *header;TAILQ_FOREACH(header, req->input_headers, next) {evhttp_add_header( response->output_headers,(const char *)header->key,(const char *)header->value);}evhttp_send_reply(response, req->response_code, req->response_code_line, req->input_buffer);evhttp_send_reply_end(response);}struct evhttp_request *proxy_request(const char *domain,unsigned short port,int timeout_in_secs,struct evhttp_request *response){struct evhttp_connection *evhttp_connection = NULL;struct evhttp_request *evhttp_request = NULL;evhttp_connection = evhttp_connection_new(domain, port);//evhttp_connection_set_local_address(evhttp_connection, &local_addr); //可以为每个连接设置本地IP，一台机可以多个IP，就可超过65535－1024个连接evhttp_request = evhttp_request_new(reqcb, (void*)response);evhttp_request->chunk_cb = chunkcb;struct evkeyval *header;TAILQ_FOREACH(header, response->input_headers, next) {evhttp_add_header( evhttp_request->output_headers,(const char *)header->key,(const char *)header->value);}if (response->type == EVHTTP_REQ_POST){evbuffer_add_buffer(evhttp_request->output_buffer , response->input_buffer);}evhttp_make_request(evhttp_connection, evhttp_request, response->type, response->uri);evhttp_connection_set_timeout(evhttp_request->evcon, timeout_in_secs);event_loop(EVLOOP_NONBLOCK);return evhttp_request;}/* 处理函数 */void pushproxy_handler(struct evhttp_request *req, void *arg){fprintf(stdout, "request %s/n", req->uri);/* 只处理GET与POST请求 */if (EVHTTP_REQ_GET != req->type && EVHTTP_REQ_POST != req->type){goto response;}if(!proxy_request(proxy_host, proxy_port, proxy_timeout_in_secs, req)){fprintf(stderr, "connect to server fail.");goto response;}// struct evbuffer *buf;// buf = evbuffer_new(); /* 分析URL参数 ,接收GET表单参数, 修改代码根据不同的url反向代理在不同的服务器 */// char *decode_uri = strdup((char*) evhttp_request_uri(req));// struct evkeyvalq http_query;//evhttp_parse_query(decode_uri, &http_query);//free(decode_uri);//const char *input_uid = evhttp_find_header (&http_query, "uid"); /* 队列名称 *///if ( NULL == input_uid || 0 == strlen(input_uid) )//{//evhttp_send_reply(req, HTTP_NOTFOUND, "404 Not Found.", buf);//goto response;//}/* 内存释放 *///evhttp_clear_headers(&http_query);//evbuffer_free(buf);return;response:evhttp_send_error(req, 502, "Bad Gateway.");return;}int main(int argc, char **argv){char *pushproxy_settings_listen = "0.0.0.0";int pushproxy_settings_port = 8008;int pushproxy_settings_timeout = 60;/* 请求处理部分 */struct evhttp *httpd;event_init();httpd = evhttp_start(pushproxy_settings_listen,pushproxy_settings_port);if (httpd == NULL) {fprintf(stderr, "Error: Unable to listen on %s:%d/n/n", pushproxy_settings_listen, pushproxy_settings_port);exit(1);}evhttp_set_timeout(httpd, pushproxy_settings_timeout);/* Set a callback for all other requests. */evhttp_set_gencb(httpd, pushproxy_handler, NULL);fprintf(stdout, "ok: going in loop event