Thread: Very Basic Telnet/Mud Client - coding n00b

Originally Posted by Cebb

Is it possible to share a socket between two threads?

Yes, but you will have to use mutex locks on it or you will end up with a nasty mess. Do not bother trying come up with (apparently) clever ways to circumvent this issue; you must use a thread safe form of locking on ALL SHARED VARIABLES, INCLUDING FD's (such as a socket). WRT to pthreads, your standard thread-safe lock is the mutex. End of story. Use a mutex, or get f-uped.

Perhaps your problem is this:

Code:

pthread_create(&thr, NULL, &SockList, &sockfd)

    int sockfd, n, c;
    sockfd = (int)arg;

So arg is a pointer to an int, then you assign the pointer value to your sockfd inside the thread. I think you want to dereference arg first:

Code:

sockfd = (int)(*arg);
or
sockfd = *(int*)arg;

YAY! Successful Mud Session!

Now, any suggestions as to how to make the fgets non blocking?

Code:

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h> 

void error(const char *msg)
{
    perror(msg);
    exit(0);
}

int main(int argc, char *argv[])
{
    int sockfd, portno, n, c;
    struct sockaddr_in serv_addr;
    struct hostent *server;

    char buffer[256];
    if (argc < 3) {
       fprintf(stderr,"usage %s hostname port\n", argv[0]);
       exit(0);
    }
    portno = atoi(argv[2]);
    sockfd = socket(AF_INET, SOCK_STREAM, 0);
    if (sockfd < 0) 
        error("ERROR opening socket");
    server = gethostbyname(argv[1]);
    if (server == NULL) {
        fprintf(stderr,"ERROR, no such host\n");
        exit(0);
    }
    bzero((char *) &serv_addr, sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;
    bcopy((char *)server->h_addr, 
         (char *)&serv_addr.sin_addr.s_addr,
         server->h_length);
    serv_addr.sin_port = htons(portno);
    if (connect(sockfd,(struct sockaddr *) &serv_addr,sizeof(serv_addr)) < 0) 
        error("ERROR connecting");
    c = 1;
    while(c > 0) {
        do {
            bzero(buffer,256);
            n = read(sockfd,buffer,255);
            if (n < 0) {
                c = 0;
                printf("Closing Connection");
            }
            printf("%s",buffer);        
        } while (strlen(buffer) == 255);    
    bzero(buffer,256);
    fgets(buffer,255,stdin);
    n = write(sockfd,buffer,strlen(buffer));
    }
    close(sockfd);
    return 0;
}

Originally Posted by Cebb

Code:

        do {
            printf("Buffer Clear \n");
            bzero(buffer,256);
            printf("Buffer Reading ...");
            n = read(sockfd,buffer,255);
            printf("Buffer Read.\n");
            printf("%s",buffer);
            printf("\n");
            printf(" BUFFER DONE : ");
            printf("%d",n);
            printf("\n");
        } while (n > 0);

My guess is that bzero is hanging.... maybe because the buffer only had 118 characters? Or in the login, the server sent something that is causing a pause. Any insight?
An

I think your read was hanging, because the mud was waiting for your to type something. There was no newline on "Buffer Reading ..." so you didn't see that as it was waiting on a read.


Quzah.

You'll need to use threads, or something like the ncurses library, which I believe lets you read key hits instead of line buffering. I haven't used it in a long time.


Quzah.