Linux使用Libevent库实现一个网页服务器---C语言程序

Web服务器

这一个库的实现
其他的知识都是这一个专栏里面的文章

实际使用

编译的时候需要有一个libevent库

gcc httpserv.c -o httpserv -levent

实际使用的时候需要指定端口以及共享的目录

./httpserv 80 .

这一个函数会吧这一个文件夹下面的所有文件共享出去

在这里插入图片描述

实际的效果, 这里我是把我的笔记共享了一下

实现目标

使用libevent库进行处理客户端连接(listener_cb)
时候http协议和浏览器进行连接
获取连接以后把服务启的某个文件夹下面的文件目录返回
可以根据返回的目录获取文件信息(bufferevent的读回调函数)
日志会在http.log文件里面

/*************************************************************************
  > File Name: http0.c
  > Author: XvSenfeng
  > Mail: 1458612070@qq.com 
  > Created Time: Thu 18 Apr 2024 11:11:53 AM CST
 ************************************************************************/

#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <event2/event.h>
#include <event2/listener.h>
#include <event2/bufferevent.h>
#include <signal.h>
#include <arpa/inet.h>
#include <ctype.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <dirent.h>

//读取一行
int get_line(struct bufferevent *bev, char *buf, int size){
	int i = 0;
	char c = '\0';
	int n;
	static char temp, todeal = 0;
	if(todeal == 1){
		buf[0] = temp;
		i++;
		todeal = 0;
	}
	while((i < size - 1) && (c != '\n')){
		n = bufferevent_read(bev, &c, 1);
		if(n > 0){
			if(c == '\r'){
				n = bufferevent_read(bev, &temp, 1);
				if((n > 0) && (temp == '\n')){
					buf[i++] = temp;
					break;
				}else{
					buf[i++] = '\n';
					todeal = 1;
					break;
				}
			}
			buf[i] = c;
			i++;
		}else{
			c = '\n';
		}
	}
	buf[i] = '\0';
	if(n == -1){
		i = n;
	}
	return i;
}
//根据文件的后缀, 获取文件的类型(用于HTTP协议通讯)
//name:文件名
//type:传出参数
void get_file_type(const char *name, char *type){
	if(strstr(name, ".html")){
		strcpy(type, "text/html; charset=utf-8");
	}else if(strstr(name, ".jpg")){
		strcpy(type, "image/jpeg");
	}else if(strstr(name, ".png")){
		strcpy(type, "image/png");
	}else if(strstr(name, ".gif")){
		strcpy(type, "image/gif");
	}else if(strstr(name, ".wav")){
		strcpy(type, "audio/wav");
	}else if(strstr(name, ".mp3")){
		strcpy(type, "audio/mp3");
	}else if(strstr(name, ".mp4")){
		strcpy(type, "video/mp4");
	}else{
		strcpy(type, "text/plain; charset=utf-8");
	}
}
//发送一个文件
//filename:文件名
//bev:使用的事件缓冲区
void send_file(const char *filename, struct bufferevent *bev){
	char buf[1024];
    //打开文件
	int fd = open(filename, O_RDONLY);
	if(fd == -1){
		perror("open error");
		exit(1);
	}
	//发送文件内容
	int len = 0;
	while((len = read(fd, buf, sizeof(buf))) > 0){
		bufferevent_write(bev, buf, len);
	}
	close(fd);
}
//发送HTTP协议的头部
//错误号，错误描述，文件类型，文件长度，bufferevent，文件名
void send_respond(int no, char *disp, char *type, long size, struct bufferevent *bev){
	//发送http响应
	char buf[1024] = {0};
	sprintf(buf, "HTTP/1.1 %d %s\r\n", no, disp);
	bufferevent_write(bev, buf, strlen(buf));
	sprintf(buf, "Content-Type: %s\r\n", type);
	bufferevent_write(bev, buf, strlen(buf));
	sprintf(buf, "Content-Length: %ld\r\n", size);
	bufferevent_write(bev, buf, strlen(buf));
	sprintf(buf, "Connection: close\r\n");
	bufferevent_write(bev, buf, strlen(buf));
	sprintf(buf, "\r\n");
	bufferevent_write(bev, buf, strlen(buf));
}
//把文本转化为URL格式, 可用于网址
void strencode(char* to, size_t 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';
}
//发送一个文件夹目录
//dirname:文件夹名字
int send_dir(struct bufferevent *bev,const char *dirname)
{
	char encoded_name[1024];
	char path[1024];
	char timestr[64];
	struct stat sb;
	struct dirent **dirinfo;
	int i;

	char *buf = malloc(10240);
	sprintf(buf, "<html><head><meta charset=\"utf-8\"><title>%s</title></head>", dirname);
	sprintf(buf+strlen(buf), "<body><h1>当前目录：%s</h1><table>", dirname);
	//添加目录内容
	int num = scandir(dirname, &dirinfo, NULL, alphasort);
	for(i=0; i<num; ++i)
	{
		// 编码
		strencode(encoded_name, sizeof(encoded_name), dirinfo[i]->d_name);

		sprintf(path, "%s%s", dirname, dirinfo[i]->d_name);
		printf("############# path = %s\n", path);
		if (lstat(path, &sb) < 0)
		{
			sprintf(buf+strlen(buf), 
					"<tr><td><a href=\"%s\">%s</a></td></tr>\n", 
					encoded_name, dirinfo[i]->d_name);
		}
		else
		{
			strftime(timestr, sizeof(timestr), 
					"  %d  %b   %Y  %H:%M", localtime(&sb.st_mtime));
			if(S_ISDIR(sb.st_mode))
			{
                //这是一个文件夹
				sprintf(buf+strlen(buf), 
						"<tr><td><a href=\"%s/\">%s/</a></td><td>%s</td><td>%ld</td></tr>\n",
						encoded_name, dirinfo[i]->d_name, timestr, sb.st_size);
			}
			else
			{
                //这是一个普通文件
				sprintf(buf+strlen(buf), 
						"<tr><td><a href=\"%s\">%s</a></td><td>%s</td><td>%ld</td></tr>\n", 
						encoded_name, dirinfo[i]->d_name, timestr, sb.st_size);
			}

		}
		if(strlen(buf)>10000)
		{
			break;	
		}
		//bufferevent_write(bev, buf, strlen(buf));
		//    memset(buf, 0, sizeof(buf));
	}
	sprintf(buf+strlen(buf), "</table></body></html>");
	send_respond(200, "OK", "text/html", strlen(buf), bev);
	bufferevent_write(bev, buf, strlen(buf));
	printf("################# Dir Read OK !!!!!!!!!!!!!!\n");

	return 0;
}
//发送一个错误页面
void send_404(struct bufferevent *bev){
	//发送一个404页面
	struct stat sbuf;
	stat("404.html", &sbuf);
	send_respond(404, "Not Found", "text/html", sbuf.st_size, bev);
	send_file("404.html", bev);
}
//16进制数转化为10进制, return 0不会出现
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;
}

void strdecode(char *to, char *from);
void http_request(const char *filename1, struct bufferevent *bev){
	struct stat sbuf;
	char filename[1024];
	strdecode(filename,(char *) filename1);
	int ret = stat(filename, &sbuf);
	if(ret != 0){
		perror("stat error");
		send_404(bev);
		return;
	}
	char buf[128];
	get_file_type(filename, buf);
	//判断是不是目录
	if(S_ISDIR(sbuf.st_mode)){
		send_dir(bev, filename);
	}else{
		//打开文件
		//send_respond(200, "OK", "text/html", sbuf.st_size, bev);
		send_respond(200, "OK", buf, sbuf.st_size, bev);
		send_file(filename, bev);
	}	
	printf("read cb over");
}


void read_cb(struct bufferevent *bev, void *arg){
	char line[1024];
	int len = get_line(bev, line, sizeof(line));
	if(len <= 0){
		printf("get line error\n");
		bufferevent_free(bev);
		return;
	}
	printf("http header: %s", line);
	//判断是不是空行
	if(strcmp(line, "\n") == 0 || strcmp(line, "\r\n") == 0){
		printf("空行\n");
		//断开连接
		bufferevent_free(bev);
		return;
	}
	//判断是不是请求行
	char path[1024] = {0}, protocol[20] = {0};
	sscanf(line, "%*s %s %s", path, protocol);
	//读取剩余数据
	char buf[1024] = {0};
	while(1){
		len = get_line(bev, buf, sizeof(buf));
		if(len <= 0){
			break;
		}
		if(strcmp(buf, "\n") == 0 || strcmp(buf, "\r\n") == 0){
			break;
		}
	}
	if(strncasecmp(line, "GET", 3) == 0){
		char *file = path + 1;
		if(strcmp(path, "/")==0){
			file = "./";
		}
		http_request(file, bev);
		signal_over = 1;
	}else{
		printf("POST\n");
	}
}
//写回调, 这一没啥用
void write_cb(struct bufferevent *bev, void *arg){
	printf("write_cb\n");
}
//事件callback函数, 某一次连接被打断的时候会调用这一个函数
void event_cb(struct bufferevent *bev, short events, void *arg){
	if(events & BEV_EVENT_EOF){
		printf("connection closed\n");
	}else if(events & BEV_EVENT_ERROR){
		printf("some other error\n");
	}
	bufferevent_free(bev);
}

//监听的回调函数
void listener_cb(struct evconnlistener *listener, evutil_socket_t fd, struct sockaddr *addr, int socklen, void *arg){
	struct event_base *base = (struct event_base *)arg;
	struct sockaddr_in *sin = (struct sockaddr_in *)addr;
	//获取客户端ip和端口
	char ip[16];
	inet_ntop(AF_INET, &sin->sin_addr.s_addr, ip, sizeof(ip));
	printf("accept a client %s:%d\n", ip, ntohs(sin->sin_port));
	//创建bufferevent, 之后使用bufferevent的回调函数处理连接事件
	struct bufferevent *bev = bufferevent_socket_new(base, fd, 
			BEV_OPT_CLOSE_ON_FREE);
	if(bev == NULL){
		printf("bufferevent error");
		return;
	}
	//设置读写回调
	bufferevent_flush(bev, EV_READ | EV_WRITE, BEV_NORMAL);
	bufferevent_setcb(bev, read_cb, write_cb, event_cb, arg);
	bufferevent_enable(bev, EV_READ | EV_WRITE);
}
//处理信号的回调函数
void signal_cb(evutil_socket_t sig, short events, void *user_data)
{
	struct event_base *base = user_data;
	struct timeval delay = { 1, 0 };

	printf("Caught an interrupt signal; exiting cleanly in one seconds.\n");
	event_base_loopexit(base, &delay);
}
//把一个url
void strdecode(char *to, char *from)
{
	for ( ; *from != '\0'; ++to, ++from)
	{
        //检测一下下面的三个字符是不是%xx格式的
		if (from[0] == '%' && isxdigit(from[1]) && isxdigit(from[2]))
		{
			//依次判断from中 %20 三个字符, 把这三个字符转换为10进制的数字
			*to = hexit(from[1])*16 + hexit(from[2]);
			// 移过已经处理的两个字符(%21指针指向1),表达式3的++from还会再向后移一个字符
			from += 2;
		}
		else
		{
			*to = *from;
		}
	}
	*to = '\0';
}

int main(int argc, char *argv[]){
	int pid;
	//看一下参数的个数对不对
    if(argc < 3){
		printf("./serv port path");
		return 0;
	}
    //建立一个守护进程
	pid = fork();
	if(pid > 0){
		exit(1);
	}
	//切换工作目录, 使用第三个参数
	const char *path = argv[2];
	int ret = chdir(path);
	if(ret == -1){
		perror("chdir error");
		return -1;
	}
	pid = setsid();
	umask(0022);
	close(STDIN_FILENO);
	int fd;
    //一个日志文件
	fd = open("http.log", O_RDWR|O_CREAT);
	if(fd==-1){
		perror("open error");
		exit(1);
	}
	dup2(fd, STDOUT_FILENO);
	dup2(fd, STDERR_FILENO);
	//获取连接的端口
	int port = atoi(argv[1]);

	//创建服务器地址
	struct sockaddr_in serv;
	//初始化服务器地址
	memset(&serv, 0, sizeof(serv));
	serv.sin_family = AF_INET;
	serv.sin_port = htons(port);
	serv.sin_addr.s_addr = htonl(INADDR_ANY);
	//创建event_base
	struct event_base *base = event_base_new();
	if(base == NULL){
		printf("event base error");
		return -1;
	}
	//创建监听器
	struct evconnlistener *listener = evconnlistener_new_bind(
			base, listener_cb, base, 
			LEV_OPT_CLOSE_ON_FREE | LEV_OPT_REUSEABLE, -1, 
			(struct sockaddr *)&serv, sizeof(serv));
	if(listener == NULL){
		printf("listener error");
		return -1;
	}
	struct event *signal_event;
    //绑定信号回调
	signal_event = evsignal_new(base, SIGINT, signal_cb, (void *)base);
	if (!signal_event || event_add(signal_event, NULL)<0) 
	{
		fprintf(stderr, "Could not create/add a signal event!\n");
		return 1;
	}
    //开启循环
	event_base_dispatch(base);
	evconnlistener_free(listener);
	event_base_free(base);
	return 0;
}