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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" 

 

/********************** * ToonTonG＠163.com * chuantong.huang@gmail.com * 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 received void 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 completes void 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