server

server.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>

#include <sys/types.h>
#include <sys/socket.h>

#include <arpa/inet.h>
#include <netinet/in.h>
#include <pthread.h>
#include <stdbool.h>

#define SA struct sockaddr // cast shortener
#define SERVER_TICKRATE 300 // every 300ms is a tick
#define SERVER_BACKLOG 50 // max 50 clients in queue

#define TIMEOUT_IN 16
#define TIMEOUT_OUT 16

int servsockfd; // global so we can pass it around functions
int usleep(__useconds_t usec); // millisecond sleep

pid_t self_pid;
char cmd_str[26];

int lengthofchar(char* tempstring)
{
    int cnt;
    int charcount;

    charcount = 0;
    for(cnt=0; tempstring[cnt]; cnt++) {
        if(tempstring[cnt] != ' ') {
            charcount++;
        }
    }
    return charcount;
}

void set_timeout(int servsockfd, int timeout_input_seconds, int timeout_output_seconds)
{
    /*
        Setting options :
        - SO_RCVTIMO, to set timeout for input operations
        - SO_SNDTIMEO, to set timeout for output operations
    */

    struct timeval timeout;
    timeout.tv_usec = 0;
    timeout.tv_sec = 0;

    timeout.tv_sec = timeout_input_seconds;
    if (setsockopt(servsockfd, SOL_SOCKET, SO_RCVTIMEO, (char *)&timeout, sizeof(timeout)) < 0) { 
        printf("setsockopt so_rcvtimeo unsuccessful : %s (Error code %d)\n", strerror(errno), errno);
    }
    else 
    {
        timeout.tv_sec = timeout_output_seconds;
        if (setsockopt(servsockfd, SOL_SOCKET, SO_SNDTIMEO, (char *)&timeout, sizeof(timeout)) < 0) { 
            printf("setsockopt so_sndtimo unsuccessful : %s (Error code %d)\n", strerror(errno), errno);
        }
    }
    //printf("Timeout set\n");
}

void handle_connection(void* p_clisock) // thread functions need to be a void pointer, and they need to accept any arg variable as a void pointer as well
{
    printf("Thread ID : %ld (",(pthread_self() / 100000));
    printf("Thread count : ");
    int sysret = system(cmd_str); // it should print here, but somehow prints before?
    if(sysret == -1) {
        printf("system() (getting thread count) unsuccessful : %s (Error code %d)\n", strerror(errno), errno);
    }
    set_timeout(servsockfd,TIMEOUT_IN,TIMEOUT_OUT);

    /*
        for(int i = 0; i < 10; i++) {
            printf("(Job %ld) : ", (pthread_self() / 1000000));
            printf("%d\n", i);
            sleep(2);
        }
    */

    int clisock = *((int*)p_clisock);
    free (p_clisock); // we don't need the pointer anymore.

    char *verif_recv_str = "Ar4#8Pzw<&M00Nk";
    char verif_send_str[110] = "4Ex{Y**y8wOh!T00";
    char recv_buf[110];

    int recv_status;
    recv_status = recv(clisock, (void *)recv_buf, (size_t)sizeof(recv_buf), 0);
    if (recv_status == -1) {
        printf("Error reading from socket : %s\n", strerror(errno));
        printf("%s (%d) \n",strerror(errno),errno);

        close(clisock);
        pthread_exit(0);
    }

    printf("\nWaiting for verification string from client ... \n");

    if (strcmp(verif_recv_str, recv_buf) == 0)
    {
        printf("[VERIFY SUCCESS] Verification string \"%s\" received\n", verif_recv_str);
        memset(&recv_buf[0], '\0', sizeof(recv_buf));

        int send_status;
        send_status = send(clisock, (void *)verif_send_str, (size_t)lengthofchar(verif_send_str), 0);

        if (send_status == -1) {
            printf("Error writing to socket : ");
            printf("%s (Error code %d) \n",strerror(errno),errno);

            close(clisock);
            pthread_exit(0);
        }
    }

    close(clisock);
    pthread_exit(0);
}

int main() {
    self_pid = getpid();
    sprintf(cmd_str, "ps hH p %d | wc -l\n", self_pid);

    servsockfd = socket(AF_INET, SOCK_STREAM, 0);
    
    struct sockaddr_in serv_addr;
    struct sockaddr_in cli_addr;

    serv_addr.sin_family = AF_INET;
    serv_addr.sin_port = htons(64912);
    serv_addr.sin_addr.s_addr = inet_addr("10.0.0.224");
    memset(&cli_addr, 0, sizeof(struct sockaddr_in)); //initializing cli_addr struct

    if (setsockopt(servsockfd, SOL_SOCKET, SO_REUSEADDR, &(int){1}, sizeof(int)) < 0) { 
        printf("setsockopt so_reuseaddr unsuccessful : %s (Error code %d)\n", strerror(errno), errno);
    }
    printf("Set reuse\n");

    printf("Binding...\n");
    
    int bind_status;
    bind_status = bind(servsockfd, (SA*)&serv_addr, sizeof(serv_addr));
    if (bind_status == -1) {
        printf("Bind unsuccessful : %s (Error code %d)\n", strerror(errno), errno);
        if (errno == 98) {
            printf("More than one process running maybe?\n");
            exit(0);
        }
    }

    int listen_status;
    printf("Listening...\n");
    listen_status = listen(servsockfd, SERVER_BACKLOG); // second param is backlog, aka how many connections can wait in one point in time
    if (listen_status == -1) {
        printf("Listen unsuccessful : %s (Error code %d)\n", strerror(errno), errno);
    }

    for (;;) {
        usleep(SERVER_TICKRATE);

        int clisock;
        socklen_t cli_addr_size = sizeof(cli_addr);
        clisock = accept(servsockfd, (SA*)&cli_addr, &cli_addr_size); // last two parameters should fill an optionable client struct for info 
        if (clisock >= 0) {
            printf("\n");
            printf("Connection accepted from : %s:%d\n", inet_ntoa(cli_addr.sin_addr), ntohs(cli_addr.sin_port));

            pthread_t sckthread;
            int *pclient = malloc(sizeof(int));
            *pclient = clisock;
            pthread_create(&sckthread, NULL, (void *)handle_connection, pclient);
        }
    }
}