10.3 libevent实现http服务器

  1. #include <stdio.h>
  2. #include <stdlib.h>
  3. #include <unistd.h>     //for getopt, fork
  4. #include <string.h>     //for strcat
  5. //for struct evkeyvalq
  6. #include <sys/queue.h>
  7. #include <event.h>
  8. //for http
  9. //#include <evhttp.h>
  10. #include <event2/http.h>
  11. #include <event2/http_struct.h>
  12. #include <event2/http_compat.h>
  13. #include <event2/util.h>
  14. #include <signal.h>
  16. #define MYHTTPD_SIGNATURE   "myhttpd v 0.0.1"
  18. //处理模块
  19. void httpd_handler(struct evhttp_request *req, void *arg) {
  20.     char output[2048] = "\0";
  21.     char tmp[1024];
  23.     //获取客户端请求的URI(使用evhttp_request_uri或直接req->uri)
  24.     const char *uri;
  25.     uri = evhttp_request_uri(req);
  26.     sprintf(tmp, "uri=%s\n", uri);
  27.     strcat(output, tmp);
  29.     sprintf(tmp, "uri=%s\n", req->uri);
  30.     strcat(output, tmp);
  31.     //decoded uri
  32.     char *decoded_uri;
  33.     decoded_uri = evhttp_decode_uri(uri);
  34.     sprintf(tmp, "decoded_uri=%s\n", decoded_uri);
  35.     strcat(output, tmp);
  37.     //解析URI的参数(即GET方法的参数)
  38.     struct evkeyvalq params;
  39.     //将URL数据封装成key-value格式,q=value1, s=value2
  40.     evhttp_parse_query(decoded_uri, &params);
  41.     //得到q所对应的value
  42.     sprintf(tmp, "q=%s\n", evhttp_find_header(&params, "q"));
  43.     strcat(output, tmp);
  44.     //得到s所对应的value
  45.     sprintf(tmp, "s=%s\n", evhttp_find_header(&params, "s"));
  46.     strcat(output, tmp);
  48.     free(decoded_uri);
  50.     //获取POST方法的数据
  51.     char *post_data = (char *) EVBUFFER_DATA(req->input_buffer);
  52.     sprintf(tmp, "post_data=%s\n", post_data);
  53.     strcat(output, tmp);
  55.     /*
  56.        具体的：可以根据GET/POST的参数执行相应操作，然后将结果输出
  57.        ...
  58.      */
  60.     /* 输出到客户端 */
  62.     //HTTP header
  63.     evhttp_add_header(req->output_headers, "Server", MYHTTPD_SIGNATURE);
  64.     evhttp_add_header(req->output_headers, "Content-Type", "text/plain; charset=UTF-8");
  65.     evhttp_add_header(req->output_headers, "Connection", "close");
  66.     //输出的内容
  67.     struct evbuffer *buf;
  68.     buf = evbuffer_new();
  69.     evbuffer_add_printf(buf, "It works!\n%s\n", output);
  70.     evhttp_send_reply(req, HTTP_OK, "OK", buf);
  71.     evbuffer_free(buf);
  73. }
  74. void show_help() {
  75.     char *help = "http://localhost:8080\n"
  76.         "-l <ip_addr> interface to listen on, default is 0.0.0.0\n"
  77.         "-p <num>     port number to listen on, default is 1984\n"
  78.         "-d           run as a deamon\n"
  79.         "-t <second>  timeout for a http request, default is 120 seconds\n"
  80.         "-h           print this help and exit\n"
  81.         "\n";
  82.     fprintf(stderr,"%s",help);
  83. }
  84. //当向进程发出SIGTERM/SIGHUP/SIGINT/SIGQUIT的时候，终止event的事件侦听循环
  85. void signal_handler(int sig) {
  86.     switch (sig) {
  87.         case SIGTERM:
  88.         case SIGHUP:
  89.         case SIGQUIT:
  90.         case SIGINT:
  91.             event_loopbreak();  //终止侦听event_dispatch()的事件侦听循环，执行之后的代码
  92.             break;
  93.     }
  94. }
  96. int main(int argc, char *argv[]) {
  97.     //自定义信号处理函数
  98.     signal(SIGHUP, signal_handler);
  99.     signal(SIGTERM, signal_handler);
  100.     signal(SIGINT, signal_handler);
  101.     signal(SIGQUIT, signal_handler);
  103.     //默认参数
  104.     char *httpd_option_listen = "0.0.0.0";
  105.     int httpd_option_port = 8080;
  106.     int httpd_option_daemon = 0;
  107.     int httpd_option_timeout = 120; //in seconds
  109.     //获取参数
  110.     int c;
  111.     while ((c = getopt(argc, argv, "l:p:dt:h")) != -1) {
  112.         switch (c) {
  113.             case 'l' :
  114.                 httpd_option_listen = optarg;
  115.                 break;
  116.             case 'p' :
  117.                 httpd_option_port = atoi(optarg);
  118.                 break;
  119.             case 'd' :
  120.                 httpd_option_daemon = 1;
  121.                 break;
  122.             case 't' :
  123.                 httpd_option_timeout = atoi(optarg);
  124.                 break;
  125.             case 'h' :
  126.             default :
  127.                 show_help();
  128.                 exit(EXIT_SUCCESS);
  129.         }
  130.     }
  132.     //判断是否设置了-d，以daemon运行
  133.     if (httpd_option_daemon) {
  134.         pid_t pid;
  135.         pid = fork();
  136.         if (pid < 0) {
  137.             perror("fork failed");
  138.             exit(EXIT_FAILURE);
  139.         }
  140.         if (pid > 0) {
  141.             //生成子进程成功，退出父进程
  142.             exit(EXIT_SUCCESS);
  143.         }
  144.     }
  146.     /* 使用libevent创建HTTP Server */
  148.     //初始化event API
  149.     event_init();
  151.     //创建一个http server
  152.     struct evhttp *httpd;
  153.     httpd = evhttp_start(httpd_option_listen, httpd_option_port);
  154.     evhttp_set_timeout(httpd, httpd_option_timeout);
  156.     //指定generic callback
  157.     evhttp_set_gencb(httpd, httpd_handler, NULL);
  158.     //也可以为特定的URI指定callback
  159.     //evhttp_set_cb(httpd, "/", specific_handler, NULL);
  161.     //循环处理events
  162.     event_dispatch();
  164.     evhttp_free(httpd);
  165.     return 0;
  166. }