main.c

#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <stdlib.h>
#include "libev.h"
#include <string.h>
#include <event2/event.h>
#include <event2/bufferevent.h>
#include <event2/listener.h>

int main(int argc, char** argv){

  // 端口
  int port = atoi(argv[1]);
  // 修改进程的工作目录, 方便后续操作
  int ret = chdir(argv[2]);
  if(ret == -1){
    perror("chdir error");
    exit(1);
  }

  struct event_base* base = NULL;
  base = event_base_new();
  if(base == NULL){
    perror("event_base_new");
    exit(1);
  }

  struct sockaddr_in addr;
  addr.sin_family = AF_INET;
  addr.sin_port = htons(port);
  addr.sin_addr.s_addr = htonl(INADDR_ANY);

  struct evconnlistener* lis =
    evconnlistener_new_bind(base, listencb, base, LEV_OPT_CLOSE_ON_FREE | LEV_OPT_REUSEABLE, -1, (struct sockaddr*)&addr, sizeof(addr));

  if(!lis){
    perror("evconnlistener_new_bind");
    exit(1);
  }

  event_base_dispatch(base);
  event_base_free(base);
}

libev.h

#ifndef __LIBEV__
#define __LIBEV__

#include <event2/bufferevent.h>
#include <event2/listener.h>

void listencb(struct evconnlistener* listener, evutil_socket_t fd,
          struct sockaddr* cli, int len, void* ptr);
void readcb  (struct bufferevent* bev,void* ctx);
void writecb (struct bufferevent* bev,void* ctx);
void eventcb (struct bufferevent* bev,short what,void* ctx);
#endif

libev.c

#include "libev.h"
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include "libev.h"
#include <event2/event.h>
#include <event2/bufferevent.h>
#include <event2/buffer.h>
#include <string.h>
#include <sys/stat.h>
#include <stdlib.h>
#include <ctype.h>
#include <fcntl.h>
#include <unistd.h>
#include <dirent.h>

// 通过文件名获取文件的类型
const char *get_file_type(const char *name){
  char* dot;

  // 自右向左查找‘.’字符, 如不存在返回NULL
  dot = strrchr(name, '.');
  if (dot == NULL)
    return "text/plain; charset=utf-8";
  if (strcmp(dot, ".html") == 0 || strcmp(dot, ".htm") == 0)
    return "text/html; charset=utf-8";
  if (strcmp(dot, ".jpg") == 0 || strcmp(dot, ".jpeg") == 0)
    return "image/jpeg";
  if (strcmp(dot, ".gif") == 0)
    return "image/gif";
  if (strcmp(dot, ".png") == 0)
    return "image/png";
  if (strcmp(dot, ".css") == 0)
    return "text/css";
  if (strcmp(dot, ".au") == 0)
    return "audio/basic";
  if (strcmp( dot, ".wav" ) == 0)
    return "audio/wav";
  if (strcmp(dot, ".avi") == 0)
    return "video/x-msvideo";
  if (strcmp(dot, ".mov") == 0 || strcmp(dot, ".qt") == 0)
    return "video/quicktime";
  if (strcmp(dot, ".mpeg") == 0 || strcmp(dot, ".mpe") == 0)
    return "video/mpeg";
  if (strcmp(dot, ".vrml") == 0 || strcmp(dot, ".wrl") == 0)
    return "model/vrml";
  if (strcmp(dot, ".midi") == 0 || strcmp(dot, ".mid") == 0)
    return "audio/midi";
  if (strcmp(dot, ".mp3") == 0)
    return "audio/mpeg";
  if (strcmp(dot, ".ogg") == 0)
    return "application/ogg";
  if (strcmp(dot, ".pac") == 0)
    return "application/x-ns-proxy-autoconfig";

  return "text/plain; charset=utf-8";
}
// 16进制数转化为10进制
int hexit(char c)
{
    if (c >= '0' && c <= '9')
        return c - '0';
    if (c >= 'a' && c <= 'f')
        return c - 'a' + 10;
    if (c >= 'A' && c <= 'F')
        return c - 'A' + 10;

    return 0;
}

/*
 *  这里的内容是处理%20之类的东西！是"解码"过程。
 *  %20 URL编码中的‘ ’(space)
 *  %21 '!' %22 '"' %23 '#' %24 '$'
 *  %25 '%' %26 '&' %27 ''' %28 '('......
 *  相关知识html中的‘ ’(space)是&nbsp
 */
void encode_str(char* to, int tosize, const char* from)
{
    int tolen;

    for (tolen = 0; *from != '\0' && tolen + 4 < tosize; ++from)
    {
        if (isalnum(*from) || strchr("/_.-~", *from) != (char*)0)
        {
            *to = *from;
            ++to;
            ++tolen;
        }
        else
        {
            sprintf(to, "%%%02x", (int) *from & 0xff);
            to += 3;
            tolen += 3;
        }

    }
    *to = '\0';
}

void decode_str(char *to, char *from)
{
    for ( ; *from != '\0'; ++to, ++from  )
    {
        if (from[0] == '%' && isxdigit(from[1]) && isxdigit(from[2]))
        { 

            *to = hexit(from[1])*16 + hexit(from[2]);

            from += 2;
        }
        else
        {
            *to = *from;

        }

    }
    *to = '\0';

}

void listencb(struct evconnlistener* listener, evutil_socket_t fd,
          struct sockaddr* cli, int len, void* ptr){
  struct event_base* base = ptr;
  struct bufferevent* bev =
    bufferevent_socket_new(base, fd, BEV_OPT_CLOSE_ON_FREE);

  //set callback
  bufferevent_setcb(bev, readcb, writecb, eventcb, NULL);
  bufferevent_enable(bev, EV_READ | EV_WRITE);

}

// 断开连接的函数
void disconnect(struct bufferevent* bev){
  bufferevent_disable(bev, EV_READ | EV_WRITE);
}

void send_respond_head(struct bufferevent* bev, int no, const char* desp, const char* type, long len){
  char buf[1024] = {0};
  // 状态行
  sprintf(buf, "http/1.1 %d %s\r\n", no, desp);
  bufferevent_write(bev, buf, strlen(buf));
  // 消息报头
  memset(buf, 0, sizeof buf);
  sprintf(buf, "Content-Type:%s\r\n", type);
  sprintf(buf+strlen(buf), "Content-Length:%ld\r\n", len);
  bufferevent_write(bev, buf, strlen(buf));
  // 空行
  bufferevent_write(bev, "\r\n", 2);
}

void send_file(struct bufferevent* bev, const char* path){
  int fd = open(path, O_RDONLY);
  if(fd == -1){
    //todo 404
    perror("open err");
    exit(1);
  }

  char buf[4096];
  int ret = 0;
  while((ret = read(fd, buf, sizeof buf)) > 0){
    bufferevent_write(bev, buf, ret);
  }
  if(ret == -1){
    perror("read err");
    exit(1);
  }
  close(fd);
}

void send_dir(struct bufferevent* bev, const char* path){
  char file[1024] = {0};
  char buf[4096] = {0};
  sprintf(buf, "<html><head><title>目录名: %s</title></head>", path);
  sprintf(buf+strlen(buf), "<body><h1>当前目录: %s</h1><table>", path);
#if 1
  DIR* dir = opendir(path);
  if(dir == NULL){
    perror("opendir error");
    exit(1);
  }
  // 读目录
  char enstr[1024] = {0};
  struct dirent* ptr = NULL;
  while((ptr = readdir(dir)) != NULL){
    char* name = ptr->d_name;
    // 拼接文件的完整路径
    sprintf(file, "%s/%s", path, name);

    encode_str(enstr, sizeof(enstr), name);
    struct stat st;
    int ret = stat(file, &st);
    if(ret == -1){
      perror("stat err");
      exit(1);
    }
    // 如果是文件
    if(S_ISREG(st.st_mode)){
      sprintf(buf+strlen(buf),
          "<tr><td><a href=\"%s\">%s</a></td><td>%ld</td></tr>",
          enstr, name, (long)st.st_size);
    }
    // 如果是目录
    else if(S_ISDIR(st.st_mode)){
      sprintf(buf+strlen(buf),
          "<tr><td><a href=\"%s/\">%s/</a></td><td>%ld</td></tr>",
          enstr, name, (long)st.st_size);
    }
    bufferevent_write(bev, buf, strlen(buf));
    memset(buf, 0, sizeof(buf));
  }
  sprintf(buf+strlen(buf), "</table></body></html>");
  bufferevent_write(bev, buf, strlen(buf));
  closedir(dir);
#endif
}

void http_get_request(const char* line, struct bufferevent* bev){
  char method[12] = {0};
  char res[1024] = {0};
  sscanf(line, "%[^ ] %[^ ]", method, res);

  // 转码 将不能识别的中文乱码 - > 中文
  // 解码 %23 %34 %5f
  char destr[1024];
  decode_str(destr, res);
  // 处理path  /xx
  // 去掉path中的/
  char* file = destr + 1;
  char fbuf[1024];
  if(strcmp(res, "/") == 0){
    file = "./";
    //getcwd(fbuf, sizeof(fbuf));
    //printf("root:[%s]\n", fbuf);
    //   file = fbuf;
  }

  struct stat st;
  printf("file:[%s]\n", file);
  int ret = stat(file, &st);
  if(ret == -1){
    //todo 404
    perror("stat error");
    exit(1);
  }
  if(S_ISDIR(st.st_mode)){
    //dir
    // 发送头信息
    send_respond_head(bev, 200, "OK", get_file_type(".html"), 100000);
    send_dir(bev, file);
  }
  else if(S_ISREG(st.st_mode)){
    //reg file
    send_respond_head(bev, 200, "OK", get_file_type(file), st.st_size);
    send_file(bev, file);
  }
}

void readcb  (struct bufferevent* bev,void* ctx){
  struct evbuffer* evbuf = bufferevent_get_input(bev);

  char* line;
  size_t len;
  line = evbuffer_readln(evbuf, &len, EVBUFFER_EOL_CRLF);
  /*
  char* tmp = line;
  while(1){
    tmp = evbuffer_readln(evbuf, &len, EVBUFFER_EOL_CRLF);
    if(tmp) break;
    printf("%s\n", tmp);
  }
  printf("line:[%s]", line);
  */
  if(strncasecmp("get", line, 3) == 0){
    http_get_request(line, bev);
    //disconnect(bev);
  }

}
void writecb (struct bufferevent* bev,void* ctx){

}
void eventcb (struct bufferevent* bev,short what,void* ctx){

}

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原文地址：https://www.cnblogs.com/xiaoshiwang/p/11159368.html