libevent http库-使用示例

最近两天，需要给客户提供一个程序状态的http查询接口，一开始想用nginx访问fcgi，但是觉得复杂了，就一个状态查询功能而已。于是就使用了 libevent提供的http库。

使用完后总是要分享一下的，开始源码分享吧

/************************************************************************* *   > File Name: http.c *   > Author: liuqianghua *   > Mail: [e-mail] *   > Created Time: Wed 20 Sep 2017 07:17:48 AM CST ************************************************************************/#include <signal.h>#include <event2/event.h>#include <event2/http.h>#include <event2/buffer.h>#include <event2/keyvalq_struct.h>static void hello_request_cb(struct evhttp_request *req, void *arg);static void version_cb (struct evhttp_request *req, void *arg);int main(int argc, char **argv){    struct event_base *base;    struct evhttp *http;    struct evhttp_bound_socket *handle;    if (signal(SIGPIPE, SIG_IGN) == SIG_ERR)        return (1);    /* firstly, you should build a event_base looper */    base = event_base_new();    if (!base) {        fprintf(stderr, "Couldn't create an event_base: exiting\n");        return 1;    }    /* sencondly, Create a new evhttp object to handle requests. */    http = evhttp_new(base);    if (!http) {        fprintf(stderr, "couldn't create evhttp. Exiting.\n");        return 1;    }    /* 想想我们在nginx里面配的各种uri，就知道这是什么了，是的就是那个东西*/    evhttp_set_cb(http, "/hello", hello_request_cb, NULL);    /* We want to accept arbitrary requests, so we need to set a "generic"     *   * cb.  We can also add callbacks for specific paths. */    /* 这是一个兜底的回调，即上面的各种uri都未匹配的情况下，进入这个通用的匹配，     * 就相当于nginx的404页面或者nginx version的页面的作用*/    evhttp_set_gencb(http, version_cb, argv[1]);    /* Now we tell the evhttp what port to listen on */    handle = evhttp_bind_socket_with_handle(http, "0.0.0.0", 8090);    if (!handle) {        fprintf(stderr, "couldn't bind to port %d. Exiting.\n",                (int)8090);        return 1;    }    event_base_dispatch(base);    return 0;}static void hello_request_cb(struct evhttp_request *req, void *arg){    const char *cmdtype;    struct evkeyvalq *headers;    struct evkeyval *header;    struct evbuffer *buf;    switch (evhttp_request_get_command(req)) {        case EVHTTP_REQ_GET: cmdtype = "GET"; break;        case EVHTTP_REQ_POST: cmdtype = "POST"; break;        case EVHTTP_REQ_HEAD: cmdtype = "HEAD"; break;        case EVHTTP_REQ_PUT: cmdtype = "PUT"; break;        case EVHTTP_REQ_DELETE: cmdtype = "DELETE"; break;        case EVHTTP_REQ_OPTIONS: cmdtype = "OPTIONS"; break;        case EVHTTP_REQ_TRACE: cmdtype = "TRACE"; break;        case EVHTTP_REQ_CONNECT: cmdtype = "CONNECT"; break;        case EVHTTP_REQ_PATCH: cmdtype = "PATCH"; break;        default: cmdtype = "unknown"; break;    }    printf("Received a %s request for %s\nHeaders:\n",            cmdtype, evhttp_request_get_uri(req));    headers = evhttp_request_get_input_headers(req);    for (header = headers->tqh_first; header;            header = header->next.tqe_next) {        printf("  %s: %s\n", header->key, header->value);    }    buf = evhttp_request_get_input_buffer(req);    /* 读取报文实体的数据 */    puts("Input data: <<<");    while (evbuffer_get_length(buf)) {        int n;        char cbuf[128];        n = evbuffer_remove(buf, cbuf, sizeof(buf)-1);        if (n > 0)            (void) fwrite(cbuf, 1, n, stdout);    }    /* 向报文实体输出数据 */    puts(">>>");    evhttp_send_reply(req, 200, "OK", NULL);}static void version_cb (struct evhttp_request *req, void *arg){    fprintf (stderr, "what is my version \n");    evhttp_send_reply(req, 200, "OK", NULL);}

编译 gcc -g http.c -levent 

运行 ./a.out 

在浏览器中分别输入 

http://192.168.47.131:8090/hello2

http://192.168.47.131:8090/hello

得到如下输出：

what is my version 
Received a GET request for /hello
Headers:
  Host: 192.168.47.131:8090
  User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:55.0) Gecko/20100101 Firefox/55.0
  Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
  Accept-Language: zh-CN,zh;q=0.8,en-US;q=0.5,en;q=0.3
  Accept-Encoding: gzip, deflate
  Connection: keep-alive
  Upgrade-Insecure-Requests: 1
Input data: <<<
>>>