我正在尝试将服务器中的在线用户显示给客户端。我已经声明了一个client_struct，它在客户端连接时存储必要的信息。每次用户通过身份验证并希望与服务器通信时，我都会派生一个子进程。但是，当第二个用户连接到服务器时，客户端程序只显示 1 个当前在线用户并停止工作。任何原因？现在已经连续 4 小时破解代码了。
服务器
/*
C socket server example
*/
#include<stdio.h>
#include<string.h> //strlen
#include<sys/socket.h>
#include<arpa/inet.h> //inet_addr
#include<unistd.h> //write
struct client_struct{
char ip[20];
char username[20];
char password[20];
int busy;
int online;
int user_number;
};
struct client_struct client_database[25];
char users_online[20][20];
int user_count=0;
int main(int argc , char *argv[])
{
int socket_desc , client_sock , c , read_size,i,j=0,not_valid=1,l;
struct sockaddr_in server , client;
char client_message[2000],username_database[25][25],password_database[25][25],str[INET_ADDRSTRLEN],username[20],password[20],garbage[20];
unsigned long clients[25];
strcpy(client_database[0].username,"rushabh");
strcpy(client_database[0].password,"nagda");
//client_database[0].busy=0;
//client_database[0].online=0;
//client_database[0].user_number=0;
strcpy(client_database[1].username,"sahil");
strcpy(client_database[1].password,"gill");
//client_database[1].busy=0;
//client_database[1].online=0;
//client_database[1].user_number=0;
strcpy(client_database[2].username,"panty");
strcpy(client_database[2].password,"avi");
//client_database[2].busy=0;
//client_database[2].online=0;
//client_database[2].user_number=0;
//Create socket
socket_desc = socket(AF_INET , SOCK_STREAM , 0);
if (socket_desc == -1)
{
printf("Could not create socket");
}
puts("Socket created");
//Prepare the sockaddr_in structure
server.sin_family = AF_INET;
server.sin_addr.s_addr = INADDR_ANY;
server.sin_port = htons( 8888 );
//Bind
if( bind(socket_desc,(struct sockaddr *)&server , sizeof(server)) < 0)
{
//print the error message
perror("bind failed. Error");
return 1;
}
puts("bind done");
//Listen
listen(socket_desc , 3);
//Accept and incoming connection
puts("Waiting for incoming connections...");
c = sizeof(struct sockaddr_in);
//accept connection from an incoming client
while(1)
{
client_sock = accept(socket_desc, (struct sockaddr *)&client, (socklen_t*)&c);
//Incrementing usercount
inet_ntop(AF_INET, &(client.sin_addr), str, INET_ADDRSTRLEN); //extracting ip address
printf("%s\n", str); // prints "192.0.2.33"
//if(fork()==0) //remember that this is wrong!
//{
//printf("%u\n",client.sin_addr.s_addr);
//clients[user_count]=client.sin_addr.s_addr;
if (client_sock < 0)
{
perror("accept failed");
return 1;
}
puts("Connection accepted");
//User authentication
write(client_sock,"Please enter username:",strlen("Please enter username\n"));
recv(client_sock,username,20,0);
write(client_sock,"Please enter password:",strlen("Please enter password\n"));
recv(client_sock,password,20,0);
//Authentication
for(j=0;j<3;j++)
{
//printf("%s %s %s %s\n",client_database[j].username,username,client_database[j].password,password);
if(!(strcmp(client_database[j].username,username)) ||
!(strcmp(client_database[j].password,password)))
{
printf("yay!\n");
write(client_sock,"Authenticated\n",strlen("Authenticated\n"));
recv(client_sock,garbage,20,0);
client_database[j].online=1;
client_database[j].busy=0;
strcpy(client_database[j].ip,str);
not_valid=0;
break;
}
}
if(not_valid==1)
{
write(client_sock,"Invalid username or password\n",strlen("Invalid username or password\n"));
recv(client_sock,garbage,20,0);
return(0);
}
if(fork()==0)
{
write(client_sock,"The online users are",strlen("The online users are"));
recv(client_sock,garbage,20,0);
for(l=0;l<20;l++)
{
if(client_database[l].online==1)
{
write(client_sock,client_database[l].username,strlen(client_database[l].username));
recv(client_sock,garbage,20,0);
}
else
{
printf("%s %d\n",client_database[l].username,client_database[l].online);
write(client_sock,"garbage",strlen("garbage"));
recv(client_sock,garbage,20,0);
}
}
//Receive a message from client
while( (read_size = recv(client_sock , client_message , 2000 , 0)) > 0 )
{
//Send the message back to client
write(client_sock , client_message , strlen(client_message));
puts(client_message);
memset(&client_message[0], 0, sizeof(client_message));
}
if(read_size == 0)
{
puts("Client disconnected");
fflush(stdout);
}
else if(read_size == -1)
{
perror("recv failed");
}
}
//}
}
return 0;
}
客户
/*
C ECHO client example using sockets
*/
#include<stdio.h> //printf
#include<string.h> //strlen
#include<sys/socket.h> //socket
#include<arpa/inet.h> //inet_addr
int main(int argc , char *argv[])
{
int sock,i=0,username_counter=0;
struct sockaddr_in server;
char message[1000] , server_reply[2000],server_reply1[2000];
//Create socket
sock = socket(AF_INET , SOCK_STREAM , 0);
printf("%d\n",sock);
if (sock == -1)
{
printf("Could not create socket");
}
puts("Socket created");
server.sin_addr.s_addr = inet_addr("127.0.0.1");
server.sin_family = AF_INET;
server.sin_port = htons( 8888 );
//Connect to remote server
if (connect(sock , (struct sockaddr *)&server , sizeof(server)) < 0)
{
perror("connect failed. Error");
return 1;
}
puts("Connected\n");
while(1)
{
recv(sock,server_reply,2000,0); //rec username
puts(server_reply);
scanf("%s",message);
send(sock,message,strlen(message),0);
memset(&server_reply[0], 0, sizeof(server_reply));
recv(sock,server_reply,2000,0); //recv password
puts(server_reply);
scanf("%s",message);
send(sock,message,strlen(message),0);
memset(&server_reply[0], 0, sizeof(server_reply));
recv(sock,server_reply,2000,0); //auth
puts(server_reply);
send(sock,"foo",strlen("foo"),0);
memset(&server_reply[0], 0, sizeof(server_reply));
recv(sock,server_reply,2000,0); //online users
puts(server_reply);
send(sock,"foo",strlen("foo"),0);
memset(&server_reply[0], 0, sizeof(server_reply));
while(1)
{
if(username_counter==20)
{
break;
}
recv(sock,server_reply,2000,0);
if(strcmp(server_reply,"garbage"))
puts(server_reply);
memset(&server_reply[0], 0, sizeof(server_reply));
send(sock,"foo",strlen("foo"),0);
username_counter++;
}
/*memset(&server_reply[0], 0, sizeof(server_reply));
recv(sock,server_reply,2000,0);
puts(server_reply);
memset(&server_reply[0], 0, sizeof(server_reply));
recv(sock,server_reply,2000,0);
puts(server_reply);*/
break;
}
printf("Authenticated\n");
memset(&server_reply[0], 0, sizeof(server_reply));
//keep communicating with server
while(1)
{
printf("Enter message : ");
scanf("%s" , message);
//Send some data
if( send(sock , message , strlen(message) , 0) < 0)
{
puts("Send failed");
return 1;
}
//Receive a reply from the server
if( recv(sock , server_reply , 2000 , 0) < 0)
{
puts("recv failed");
break;
}
puts("Server reply :");
puts(server_reply);
memset(&server_reply[0], 0, sizeof(server_reply));
}
close(sock);
return 0;
}