问题描述
我很期待实现这一点:服务器从客户端数量中接收一个字符串(文件名)，该字符串必须从文件夹中获取，并通过在命令行中定义的bufferSize将其返回给客户端.它必须通过UDP通信来实现.我熟悉TCP套接字，但是我不知道如何为udp连接获取fileDescriptor，因为accepts丢失了.
I'm looking forward to achive this: Server recieves from number of clients a string(file name) which he has to take from the folder and return it to the the client by a bufferSize which is defined from the command line. It has to be implemented with UDP communication. i'm familiarized with TCP sockets, but i don't get how can i get a fileDescriptor for the udp connection since accepts is missing.
所以我正在考虑:配置之后，我在服务器中执行一个while循环，在此我得到某种描述符"，我将其发送到一个新线程，该线程知道将数据发送回何处... 有任何想法吗?
So I'm thinking about this: after the config i do a while-loop in the server where i get 'some kind of descriptor' which i'll send to a new thread which knows where to send the data back... Any ideas?
我已经检查过网络，但是没有找到这种操作的具体解释.
I've checked the net but didn't found a concrete explanation for this kind of operation.
推荐答案
我终于找到了一些有用的东西，也许对其他人有用，所以这里是:代码已注释并且非常清晰.PS:抱歉，我粘贴的内容太长了，但是Google不允许我复制链接.
I have finally found something helpful, maybe it will be useful for others so here it is: the code is commented and really clear.PS: sorry for the long paste, but google doesn't let me copy the link.
/*
* udpserver.c - A simple UDP echo server
* usage: udpserver <port>
*/
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <netdb.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#define BUFSIZE 1024
/*
* error - wrapper for perror
*/
void error(char *msg) {
perror(msg);
exit(1);
}
int main(int argc, char **argv) {
int sockfd; /* socket */
int portno; /* port to listen on */
int clientlen; /* byte size of client's address */
struct sockaddr_in serveraddr; /* server's addr */
struct sockaddr_in clientaddr; /* client addr */
struct hostent *hostp; /* client host info */
char buf[BUFSIZE]; /* message buf */
char *hostaddrp; /* dotted decimal host addr string */
int optval; /* flag value for setsockopt */
int n; /* message byte size */
/*
* check command line arguments
*/
if (argc != 2) {
fprintf(stderr, "usage: %s <port>\n", argv[0]);
exit(1);
}
portno = atoi(argv[1]);
/*
* socket: create the parent socket
*/
sockfd = socket(AF_INET, SOCK_DGRAM, 0);
if (sockfd < 0)
error("ERROR opening socket");
/* setsockopt: Handy debugging trick that lets
* us rerun the server immediately after we kill it;
* otherwise we have to wait about 20 secs.
* Eliminates "ERROR on binding: Address already in use" error.
*/
optval = 1;
setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR,
(const void *)&optval , sizeof(int));
/*
* build the server's Internet address
*/
bzero((char *) &serveraddr, sizeof(serveraddr));
serveraddr.sin_family = AF_INET;
serveraddr.sin_addr.s_addr = htonl(INADDR_ANY);
serveraddr.sin_port = htons((unsigned short)portno);
/*
* bind: associate the parent socket with a port
*/
if (bind(sockfd, (struct sockaddr *) &serveraddr,
sizeof(serveraddr)) < 0)
error("ERROR on binding");
/*
* main loop: wait for a datagram, then echo it
*/
clientlen = sizeof(clientaddr);
while (1) {
/*
* recvfrom: receive a UDP datagram from a client
*/
bzero(buf, BUFSIZE);
n = recvfrom(sockfd, buf, BUFSIZE, 0,
(struct sockaddr *) &clientaddr, &clientlen);
if (n < 0)
error("ERROR in recvfrom");
/*
* gethostbyaddr: determine who sent the datagram
*/
hostp = gethostbyaddr((const char *)&clientaddr.sin_addr.s_addr,
sizeof(clientaddr.sin_addr.s_addr), AF_INET);
if (hostp == NULL)
error("ERROR on gethostbyaddr");
hostaddrp = inet_ntoa(clientaddr.sin_addr);
if (hostaddrp == NULL)
error("ERROR on inet_ntoa\n");
printf("server received datagram from %s (%s)\n",
hostp->h_name, hostaddrp);
printf("server received %d/%d bytes: %s\n", strlen(buf), n, buf);
/*
* sendto: echo the input back to the client
*/
n = sendto(sockfd, buf, strlen(buf), 0,
(struct sockaddr *) &clientaddr, clientlen);
if (n < 0)
error("ERROR in sendto");
}
}
这篇关于UDP多客户端服务器基础知识的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！