我需要使用套接字在C中编写一个聊天程序,我遇到了困难 .
我有三个文件:server,client1,client2 . 我的初步计划: - Client1将消息发送到服务器
-
Server收到它并将其发送给Client2
-
Client2接收Client1的消息,写回来并将其发送到服务器
-
Server收到Client2的消息并将其发送给Client1
-
Client1接收它并写回一些由服务器等首先接收的内容.etc.etc .
当任一客户端发送“退出”时,循环结束 .
我的问题用几句话说:
-
第一次交换成功(Client1 - > Client2,然后Client2到Client1)
-
但是,在Client2将其第一条消息发送到Client1之后,他不会等待Client1的响应 . 他用消息的空行写“Client1:”,然后立即打开他自己的“Client2:”消息字段 .
上帝的名字在这里可能是错的?
Client1.c
#include <stdio.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <string.h>
int compare_strings(char a[], char b[])
{
int c = 0;
while (a[c] == b[c])
{
if (a[c] == '\0' || b[c] == '\0')
break;
c++;
}
if (a[c] == '\0' && b[c] == '\0')
return 0;
else
return -1;
}
int main() {
int clientSocket;
char buffer[1024];
struct sockaddr_in serverAddr;
socklen_t addr_size;
int cmdEXIT = 0;
clientSocket = socket(PF_INET, SOCK_STREAM, 0);
serverAddr.sin_family = AF_INET;
serverAddr.sin_port = htons(7891);
serverAddr.sin_addr.s_addr = inet_addr("127.0.0.1");
memset(serverAddr.sin_zero, '\0', sizeof serverAddr.sin_zero);
addr_size = sizeof serverAddr;
connect(clientSocket, (struct sockaddr *) &serverAddr, addr_size);
while (cmdEXIT == 0)
{
printf("Client 1 : ");
scanf(" %[^\n]s", buffer);
send(clientSocket,buffer,sizeof buffer - 1,0);
if (compare_strings(buffer, "exit")==-1)
{
memset(&buffer[0], 0, sizeof(buffer));
recv(clientSocket, buffer, sizeof buffer - 1, 0);
if (compare_strings(buffer, "exit")==-1)
{
printf("Client 2 : ");
printf("%s\n", buffer);
memset(&buffer[0], 0, sizeof(buffer));
}
else cmdEXIT=1;
}
else cmdEXIT=1;
}
return 0;
}
Server.c
#include <stdio.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <string.h>
int compare_strings(char a[], char b[])
{
int c = 0;
while (a[c] == b[c])
{
if (a[c] == '\0' || b[c] == '\0')
break;
c++;
}
if (a[c] == '\0' && b[c] == '\0')
return 0;
else
return -1;
}
int main() {
int welcomeSocket, newSocket, Client2;
struct sockaddr_in serverAddr;
struct sockaddr_storage serverStorage;
socklen_t addr_size;
char buffer[1024];
welcomeSocket = socket(PF_INET, SOCK_STREAM, 0);
serverAddr.sin_family = AF_INET;
serverAddr.sin_port = htons(7891);
serverAddr.sin_addr.s_addr = inet_addr("127.0.01");
memset(serverAddr.sin_zero, '\0', sizeof serverAddr.sin_zero);
bind(welcomeSocket, (struct sockaddr *) &serverAddr, sizeof(serverAddr));
if (listen(welcomeSocket,5)==0)
printf("Listening\n");
else
printf("Error\n");
addr_size = sizeof serverStorage;
newSocket = accept(welcomeSocket, (struct sockaddr *) &serverStorage, &addr_size);
Client2 = accept(welcomeSocket, (struct sockaddr *) &serverStorage, &addr_size);
int cmdEXIT = 0;
while (cmdEXIT == 0)
{
recv(newSocket, buffer, 1024, 0);
printf ("%s\nEnvoie au Client2\n", buffer);
send(Client2,buffer,1024,0);
if (compare_strings(buffer, "exit")==0)
{
cmdEXIT = 1;
}
else
{
memset(&buffer[0], 0, sizeof(buffer));
recv(Client2, buffer, 1024, 0);
printf ("%s\nEnvoie au Client1\n", buffer);
send(newSocket,buffer,1024,0);
if (compare_strings(buffer, "exit")==0)
{
cmdEXIT = 1;
}
}
}
return 0;
}
Client2.c
#include <stdio.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <string.h>
int compare_strings(char a[], char b[])
{
int c = 0;
while (a[c] == b[c])
{
if (a[c] == '\0' || b[c] == '\0')
break;
c++;
}
if (a[c] == '\0' && b[c] == '\0')
return 0;
else
return -1;
}
int main() {
int clientSocket;
char buffer[1024];
struct sockaddr_in serverAddr;
socklen_t addr_size;
int cmdEXIT = 0;
clientSocket = socket(PF_INET, SOCK_STREAM, 0);
serverAddr.sin_family = AF_INET;
serverAddr.sin_port = htons(7891);
serverAddr.sin_addr.s_addr = inet_addr("127.0.0.1");
memset(serverAddr.sin_zero, '\0', sizeof serverAddr.sin_zero);
addr_size = sizeof serverAddr;
connect(clientSocket, (struct sockaddr *) &serverAddr, addr_size);
while (cmdEXIT == 0)
{
recv(clientSocket, buffer, sizeof buffer - 1, 0);
if (compare_strings(buffer, "exit")==-1)
{
printf("Client 1 : ");
printf("%s\n", buffer);
memset(&buffer[0], 0, sizeof(buffer));
printf("Client 2 : ");
scanf(" %[^\n]s", buffer);
send(clientSocket,buffer,sizeof buffer - 1,0);
if (compare_strings(buffer, "exit")==-1)
{
memset(&buffer[0], 0, sizeof(buffer));
}
else cmdEXIT = 1;
}
else cmdEXIT = 1;
}
return 0;
}
结果截图:
Client 2 being too bossy and not waiting for his turn to speak
2 回答
免责声明:我自己没有运行您的代码,因此以下分析可能是错误的 .
我建议你检查
recv
的返回值,这将在出错时返回-1
. 如果recv
在此行Client2.c中遇到错误:在while循环开始时_1113631_缓冲区将保持清零状态 .因此,客户端2不会等待客户端1的消息,并且只是为来自客户端1的消息打印空字符串 .
如果有任何帮助或您需要更多帮助,请告诉我 . 如果以上情况属实,则应确保连接不会中断等 .
所以,正如之前评论中所承诺的,这是我的解决方案 . 简而言之:每次我测试recv的 Value 是什么 . 如果它等于1,则表示没有收到消息,“线路是空闲的”,客户端可以键入自己的消息 . 否则,他必须显示收到的消息,然后才能发送他自己的文本 .
Client1.c
Server.c
Client2.c