client.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <unistd.h>
#include <signal.h>
/* #include <termios.h> */

#define BUFFER_LENGTH 256
#define SERVER_PORT 8080
#define SERVER_NAME "127.0.0.1"


int main(int argc, char* argv[])
{
    struct sockaddr_in serveraddr;

    char 
    *server,
    username[BUFFER_LENGTH], 
    target[BUFFER_LENGTH],
    buffer[BUFFER_LENGTH],
    temp[BUFFER_LENGTH],
    recieve[BUFFER_LENGTH], 
    message[BUFFER_LENGTH];

    int socket_descriptor;

    pid_t pid;

   /*  struct termios oldt, newt;
    
    tcgetattr(STDIN_FILENO, &oldt);
    newt = oldt;
    newt.c_lflag &= ~(ICANON);
    tcsetattr(STDIN_FILENO, TCSANOW, &newt); */

    do
    {   
        int 
        status = 0,
        valread,
        c;
        // socket
        socket_descriptor = socket(AF_INET, SOCK_STREAM, 0);
        if(socket_descriptor < 0)
        {
            perror("socket() failed");
            break;
        }

        if(argc > 1)
            server = strdup(argv[1]);
        else
            server = strdup(SERVER_NAME);

        puts("Chat client\nHelp:\nType \"exit()\" to exit\nType \"change()\" to change message target\n-----");
        puts("Enter a username:");
        fgets(buffer, BUFFER_LENGTH, stdin);
        strcpy(username, buffer);
        username[strcspn(username, "\n")] = '\0';
		
        // set up server info
        memset(&serveraddr, 0, sizeof(serveraddr));
        serveraddr.sin_family = AF_INET;
        serveraddr.sin_port = htons(SERVER_PORT);

        inet_pton(AF_INET, server, &serveraddr.sin_addr);
        
        // connect
        fputs("connecting...", stdout);
        status = connect(socket_descriptor, (struct sockaddr *)&serveraddr, sizeof(serveraddr));
        if(status < 0)
        {
            perror("connect() failed");
            break;
        }
        puts("\tconnected to server");
		
        status = send(socket_descriptor, username, strlen(username) + 1, 0);
        if(status <= 0)
        {
            perror("send() failed");
            break;
        }

        sleep(1);
        puts("Enter a username to send messages to:");
        fgets(buffer, BUFFER_LENGTH, stdin);
        strcpy(target, buffer);
        target[strcspn(target, "\n")] = '\0';
        puts("-----");

        int 
        leave = 1,
        *die = &leave; // pointer jic so we can reference on both forks

        pid = fork(); // 0 is child, nonzero is parent
        if(pid < 0)
        {
            perror("fork() failed");
            break;
        }
		char 
        keyword[7] = "exit()",
        change[9] = "change()";
        if(pid == 0)
        {    
            //printf("\tpid %d recieving\n", pid);
            do
            {
                // recv
                if(!*die) break;
                valread = recv(socket_descriptor, recieve, BUFFER_LENGTH, 0); 
                if (valread < 0)
                {
                    perror("recv() failed");
                    break;
                }
                else if (valread == 0)
                {
                    perror("server closed");
                    break;
                }
                recieve[valread] = '\0'; // trim string properly
                /* fgets(temp, sizeof(temp), stdin);
                c = strlen(temp)-1;
                while(c >= 0)
                {
                    ungetc(temp[c--], stdin);
                } */
                //printf("\33[0G\n%s\n\33[F", recieve);
                puts(recieve);
            } while (*die);
            //puts("closing recv() fork");
            break;
        }
        if(pid > 0)
        {
            //printf("\tpid %d sending\n", pid);
            do
            {
                //fputs(">>", stdout);
                fgets(buffer, BUFFER_LENGTH, stdin);
                buffer[strcspn(buffer, "\n")] = '\0'; // $ man strcspn
                *die = strcmp(buffer, keyword);
                if(!*die) break;
                if(!strcmp(buffer, change))
                {
                    puts("Enter a username to send messages to:");
                    fgets(buffer, BUFFER_LENGTH, stdin);
                    strcpy(target, buffer);
                    target[strcspn(target, "\n")] = '\0';
                    //continue;
                }
                else
                {
                    int message_length = (strlen(target)+strlen(username)+strlen(buffer)+6);
                    snprintf(message, message_length, "%s:%s : %s", target, username, buffer);
                    status = send(socket_descriptor, message, sizeof(message), 0);
                    if (status <= 0)
                    {
                        perror("send() failed");
                        break;
                    }
                }
            } while (*die);
            //puts("closing send() fork");
            break;
        }
        /* TODO fix user input being interrupted by recieving message
            -save user input
            -print escape character to clear line
            -print recieved message
            -print partial input from user
        */
    } while(0);
    
    /* tcsetattr(STDIN_FILENO, TCSANOW, &oldt); */
    kill(pid, SIGKILL);
    // close
    close(socket_descriptor);
    exit(EXIT_SUCCESS);

    return 0;
}