最近在工作當中接觸到libevent庫,用於http server端功能還是比較強大,特在此記錄一筆,以備後面查漏補缺。首先是下載安裝,直接去官網下載對應版本的安裝包,解壓安裝即可,這裏就不囉嗦了。
#tar
#./configure
#make
#make install
完成安裝之後,就可以開始編寫自己的示例程序了,先上代碼:
#include <stdio.h>
#include <stdlib.h>
#include <evhttp.h>
#include <event.h>
#include <string.h>
#include "event2/http.h"
#include "event2/event.h"
#include "event2/buffer.h"
#include "event2/bufferevent.h"
#include "event2/bufferevent_compat.h"
#include "event2/http_struct.h"
#include "event2/http_compat.h"
#include "event2/util.h"
#include "event2/listener.h"
#define BUF_MAX 1024*16
//解析post請求數據
void get_post_message(char *buf, struct evhttp_request *req)
{
size_t post_size = 0;
post_size = evbuffer_get_length(req->input_buffer);//獲取數據長度
printf("====line:%d,post len:%d\n",__LINE__,post_size);
if (post_size <= 0)
{
printf("====line:%d,post msg is empty!\n",__LINE__);
return;
}
else
{
size_t copy_len = post_size > BUF_MAX ? BUF_MAX : post_size;
printf("====line:%d,post len:%d, copy_len:%d\n",__LINE__,post_size,copy_len);
memcpy(buf, evbuffer_pullup(req->input_buffer,-1), copy_len);
buf[post_size] = '\0';
printf("====line:%d,post msg:%s\n",__LINE__,buf);
}
}
//解析http頭,主要用於get請求時解析uri和請求參數
char *find_http_header(struct evhttp_request *req,struct evkeyvalq *params,const char *query_char)
{
if(req == NULL || params == NULL || query_char == NULL)
{
printf("====line:%d,%s\n",__LINE__,"input params is null.");
return NULL;
}
struct evhttp_uri *decoded = NULL;
char *query = NULL;
char *query_result = NULL;
const char *path;
const char *uri = evhttp_request_get_uri(req);//獲取請求uri
if(uri == NULL)
{
printf("====line:%d,evhttp_request_get_uri return null\n",__LINE__);
return NULL;
}
else
{
printf("====line:%d,Got a GET request for <%s>\n",__LINE__,uri);
}
//解碼uri
decoded = evhttp_uri_parse(uri);
if (!decoded)
{
printf("====line:%d,It's not a good URI. Sending BADREQUEST\n",__LINE__);
evhttp_send_error(req, HTTP_BADREQUEST, 0);
return;
}
//獲取uri中的path部分
path = evhttp_uri_get_path(decoded);
if (path == NULL)
{
path = "/";
}
else
{
printf("====line:%d,path is:%s\n",__LINE__,path);
}
//獲取uri中的參數部分
query = (char*)evhttp_uri_get_query(decoded);
if(query == NULL)
{
printf("====line:%d,evhttp_uri_get_query return null\n",__LINE__);
return NULL;
}
//查詢指定參數的值
evhttp_parse_query_str(query, params);
query_result = (char*)evhttp_find_header(params, query_char);
return query_result;
}
//處理get請求
void http_handler_testget_msg(struct evhttp_request *req,void *arg)
{
if(req == NULL)
{
printf("====line:%d,%s\n",__LINE__,"input param req is null.");
return;
}
char *sign = NULL;
char *data = NULL;
struct evkeyvalq sign_params = {0};
sign = find_http_header(req,&sign_params,"sign");//獲取get請求uri中的sign參數
if(sign == NULL)
{
printf("====line:%d,%s\n",__LINE__,"request uri no param sign.");
}
else
{
printf("====line:%d,get request param: sign=[%s]\n",__LINE__,sign);
}
data = find_http_header(req,&sign_params,"data");//獲取get請求uri中的data參數
if(data == NULL)
{
printf("====line:%d,%s\n",__LINE__,"request uri no param data.");
}
else
{
printf("====line:%d,get request param: data=[%s]\n",__LINE__,data);
}
printf("\n");
//迴響應
struct evbuffer *retbuff = NULL;
retbuff = evbuffer_new();
if(retbuff == NULL)
{
printf("====line:%d,%s\n",__LINE__,"retbuff is null.");
return;
}
evbuffer_add_printf(retbuff,"Receive get request,Thamks for the request!");
evhttp_send_reply(req,HTTP_OK,"Client",retbuff);
evbuffer_free(retbuff);
}
//處理post請求
void http_handler_testpost_msg(struct evhttp_request *req,void *arg)
{
if(req == NULL)
{
printf("====line:%d,%s\n",__LINE__,"input param req is null.");
return;
}
char buf[BUF_MAX] = {0};
get_post_message(buf, req);//獲取請求數據,一般是json格式的數據
if(buf == NULL)
{
printf("====line:%d,%s\n",__LINE__,"get_post_message return null.");
return;
}
else
{
//可以使用json庫解析需要的數據
printf("====line:%d,request data:%s",__LINE__,buf);
}
//迴響應
struct evbuffer *retbuff = NULL;
retbuff = evbuffer_new();
if(retbuff == NULL)
{
printf("====line:%d,%s\n",__LINE__,"retbuff is null.");
return;
}
evbuffer_add_printf(retbuff,"Receive post request,Thamks for the request!");
evhttp_send_reply(req,HTTP_OK,"Client",retbuff);
evbuffer_free(retbuff);
}
int main()
{
struct evhttp *http_server = NULL;
short http_port = 8081;
char *http_addr = "0.0.0.0";
//初始化
event_init();
//啓動http服務端
http_server = evhttp_start(http_addr,http_port);
if(http_server == NULL)
{
printf("====line:%d,%s\n",__LINE__,"http server start failed.");
return -1;
}
//設置請求超時時間(s)
evhttp_set_timeout(http_server,5);
//設置事件處理函數,evhttp_set_cb針對每一個事件(請求)註冊一個處理函數,
//區別於evhttp_set_gencb函數,是對所有請求設置一個統一的處理函數
evhttp_set_cb(http_server,"/me/testpost",http_handler_testpost_msg,NULL);
evhttp_set_cb(http_server,"/me/testget",http_handler_testget_msg,NULL);
//循環監聽
event_dispatch();
//實際上不會釋放,代碼不會運行到這一步
evhttp_free(http_server);
return 0;
}
關於代碼,相應的註釋已經很清楚了,這裏主要說明一下編譯有關的問題,編譯的時候需要引入libevent庫相關的頭文件目錄,動態庫路徑和名稱。
編譯命令:gcc -o http_server http_server.c -I/usr/local/include/ -L/usr/local/lib/ -levent
-I/usr/local/include/ :頭文件路勁
-L/usr/local/lib/ :動態庫路勁
-levent :動態庫名稱(libevent.so)
附get請求和post請求及處理結果,使用postman工具模擬發送http命令,
下載地址:postman下載地址下載後一鍵安裝即可用。
客戶端get請求及響應:
客戶端post請求及響應:
服務端處理get請求:
服務端處理post請求: