我需要使用单个服务器(作为主服务器)和多个客户端来调试多人游戏的代码。我想使用select和FD_Set函数将这些多个客户端连接到服务器。为什么select()不会在我的代码中返回?
一旦客户端连接到服务器,我将它们的文件描述符保存在一个数组中,并检查数据是否可用于文件读取(使用select)。如果是,请阅读数据,否则我想向所有客户端广播消息。这是循环重复运行。每一秒,我都想向所有客户播放一条消息。同时,我也想从客户端接收数据。所以我在选择函数的帮助下检查数据的可用性。
这里是我的代码:
Server.c:
#include"stdio.h"
#include"stdlib.h"
#include"sys/types.h"
#include"sys/socket.h"
#include"string.h"
#include"netinet/in.h"
#include "sys/select.h"
#include <fcntl.h>
#define PORT 5000
#define BUF_SIZE 2000
#define CLADDR_LEN 100
int arr[4] = { 0 };
char clientAddr[4][CLADDR_LEN];
void main() {
struct sockaddr_in addr, cl_addr;
int sockfd, len, ret, newsockfd;
char buffer[BUF_SIZE];
fd_set fds;
int maxfd = -1;
int i = 0, j = 0;
sockfd = socket(AF_INET, SOCK_STREAM, 0);
if (sockfd < 0) {
printf("Error creating socket!\n");
exit(1);
}
printf("Socket created...\n");
memset(&addr, 0, sizeof(addr));
addr.sin_family = AF_INET;
addr.sin_addr.s_addr = INADDR_ANY;
addr.sin_port = PORT;
ret = bind(sockfd, (struct sockaddr *) &addr, sizeof(addr));
if (ret < 0) {
printf("Error binding!\n");
exit(1);
}
printf("Binding done...\n");
printf("Waiting for a connection...\n");
listen(sockfd, 4);
for (j = 0; j < 2; j++) { //infinite loop
len = sizeof(cl_addr);
newsockfd = accept(sockfd, (struct sockaddr *) &cl_addr, &len);
if (newsockfd < 0) {
printf("Error accepting connection!\n");
exit(1);
}
printf("Connection accepted...\n");
inet_ntop(AF_INET, &(cl_addr.sin_addr), clientAddr[j], CLADDR_LEN);
arr[j] = newsockfd;
printf("\n%d", newsockfd);
//FD_ZERO(&fds);
//FD_SET(newsockfd, &fds);
}
close(sockfd);
for (j = 0; j < 2; j++) {
if (arr[j] > maxfd)
maxfd = arr[j];
// FD_SET(arr[j], &fds);
// fcntl(arr[i], F_SETFL, O_NONBLOCK); //stop listening for new connections by the main process.
} //the child will continue to listen.
//the main process now handles the connected client.
while (1) {
for (i = 0; i < 2; i++) {
FD_SET(arr[i], &fds);
}
int returned = select(maxfd + 1, &fds, NULL, NULL, NULL);
if (returned) {
for (i = 0; i < 2; i++) {
if (FD_ISSET(arr[2], &fds)) {
ret = recvfrom(arr[i], (void*) &buffer, sizeof(buffer), 0,
NULL, NULL);
if (ret < 0) {
printf("Error receiving data!\n");
exit(1);
}
printf("%s", buffer);
}
}
}
for (j = 0; j < 2; j++) {
ret = sendto(arr[j], "abc", BUF_SIZE, 0,
(struct sockaddr *) &cl_addr, len);
if (ret < 0) {
printf("Error sending data!\n");
exit(1);
}
printf("Sent data to %s: %s\n", clientAddr[j], buffer);
}
}
/*while (1) {
for (j = 0; j < 2; j++) {
memset(buffer, 0, BUF_SIZE);
if (FD_ISSET(arr[j], &fds)) {
ret = recvfrom(arr[j], buffer, BUF_SIZE, 0,
(struct sockaddr *) &cl_addr, &len);
if (ret < 0) {
printf("Error receiving data!\n");
exit(1);
}
printf("Received data from %s: %s\n", clientAddr[j], buffer);
}
}
for (j = 0; j < 2; j++) {
ret = sendto(arr[j], "abc", BUF_SIZE, 0,
(struct sockaddr *) &cl_addr, len);
if (ret < 0) {
printf("Error sending data!\n");
exit(1);
}
printf("Sent data to %s: %s\n", clientAddr[j], buffer);
}
/* close(arr[0]);
close[arr[1]);
close(arr[2]);
close(arr[3]);
}*/
}
client.c:
#include"stdio.h"
#include"stdlib.h"
#include"sys/types.h"
#include"sys/socket.h"
#include"string.h"
#include"netinet/in.h"
#include"netdb.h"
#define PORT 5555
#define BUF_SIZE 2000
int main(int argc, char**argv) {
struct sockaddr_in addr, cl_addr;
int sockfd, ret;
char buffer[BUF_SIZE];
struct hostent * server;
char * serverAddr;
if (argc < 2) {
printf("usage: client < ip address >\n");
exit(1);
}
serverAddr = argv[1];
sockfd = socket(AF_INET, SOCK_STREAM, 0);
if (sockfd < 0) {
printf("Error creating socket!\n");
exit(1);
}
printf("Socket created...\n");
memset(&addr, 0, sizeof(addr));
addr.sin_family = AF_INET;
addr.sin_addr.s_addr = inet_addr(serverAddr);
addr.sin_port = PORT;
ret = connect(sockfd, (struct sockaddr *) &addr, sizeof(addr));
if (ret < 0) {
printf("Error connecting to the server!\n");
exit(1);
}
printf("Connected to the server...\n");
memset(buffer, 0, BUF_SIZE);
//printf("Enter your message(s): ");
//while (fgets(buffer, BUF_SIZE, stdin) != NULL) {
sleep(10);
ret = sendto(sockfd, "a", BUF_SIZE, 0, (struct sockaddr *) &addr, sizeof(addr));
if (ret < 0) {
printf("Error sending data!\n\t-%s", buffer);
}
ret = recvfrom(sockfd, buffer, BUF_SIZE, 0, NULL, NULL);
if (ret < 0) {
printf("Error receiving data!\n");
} else {
printf("Received: ");
fputs(buffer, stdout);
printf("\n");
}
return 0;
}
(客户端传递了一个IP地址)
This does 不行。在调试服务器时,它在选择时等待并且没有收到或发送任何内容。问题可能是什么?
你似乎检查'if(FD_ISSET(arr [2]',但你从未在'arr [2]'中描述符上调用过FD_SET(),并且忘记检查arr [0]上的FD_ISSET()和arr [1 ] – nos 2014-11-06 12:57:45