server.c

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <string.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <sys/select.h>
#include <sys/time.h>


int createSocket(int portv){
    int server_socket_data;
    server_socket_data = socket(AF_INET, SOCK_DGRAM, 0);
    if (server_socket_data < 0){
        printf("Couldn't create socket\n");
        return -1;
    }
 
    struct sockaddr_in serv_addr_data;

    // setsockopt(serv_socket_data, SOL_SOCKET, SO_REUSEADDR, &reuse, sizeof(reuse));        memset((char*)&serv_addr_data,0,sizeof(serv_addr_data));
    serv_addr_data.sin_family = AF_INET;
    serv_addr_data.sin_port = htons(portv);
    serv_addr_data.sin_addr.s_addr = INADDR_ANY;

    if (bind(server_socket_data, (struct sockaddr *)&serv_addr_data, sizeof(serv_addr_data))<0){
        perror("Bind UDP failed");
        exit(EXIT_FAILURE);
    }

    return server_socket_data;
    
            
}


int SYNC(int serv_socket, struct sockaddr_in* client_addr, socklen_t tailleaddr, int portv){
    char *buffer=malloc(sizeof(char)*1024);
    char *synack = malloc(sizeof(char)*16);

    if (recvfrom(serv_socket, buffer, sizeof(buffer), 0,
                 (struct sockaddr*)client_addr, &tailleaddr) < 0){
        printf("Couldn't receive SYN\n");
        return -1;
    }
    char* ntoa = inet_ntoa(client_addr->sin_addr);
    printf("SYN received from %s\n", ntoa);
    int ntoh = ntohs(client_addr->sin_port);
    printf("SYN received from port %d\n", ntoh);

    if (strcmp(buffer,"SYN")==0){
        int sock_data = createSocket(portv);
        printf("Sending SYNACK with port : %d\n", portv);
        sprintf(synack,"SYNACK:%d",portv);
        //printf("%s\n",synack);
        sendto(serv_socket, (const char *) synack, strlen(synack),
               MSG_CONFIRM, (const struct sockaddr *) client_addr,
               tailleaddr);
        printf("SYNACK sent\n");

        if (recvfrom(serv_socket, buffer, sizeof(buffer), 0,
                     (struct sockaddr*)client_addr, &tailleaddr) < 0){
            printf("Couldn't receive ACK\n");
            return -1;
        }
        if (strcmp(buffer,"ACK")==0){
            printf("ACK received from %s\n", ntoa);
            return sock_data;
        }else{
            printf("Recieve not an ACK");
        }

    }else{
        printf("Recieve not a SYN");
    }
    return -1;
}



int recvData(int serv_socket, struct sockaddr_in* client_addr, socklen_t tailleaddr, int portV){
    char buffer[1024];
    printf("Waiting for data on Port %d\n", portV);
    int rcv = recvfrom(serv_socket, buffer, sizeof(buffer), 0,
                 (struct sockaddr*)client_addr, &tailleaddr);
    if (rcv < 0){
        printf("Couldn't receive data\n");
        return -1;
    }
    char* ntoa = inet_ntoa(client_addr->sin_addr);
    printf("Data received from %s\n", ntoa);
    int ntoh = ntohs(client_addr->sin_port);
    printf("Data received from port %d\n", ntoh);
    printf("Data received: %s\n", buffer);
    return 0;
}

int main(int argc, char* argv[]) {
    int serv_socket = socket(AF_INET, SOCK_DGRAM, 0);
    int reuse = 1;
    struct sockaddr_in serv_addr_2;
    struct sockaddr_in client_addr;
    int portV = 3003; 

    if (argc != 2){
        perror("Not the correct number of args : Give the server port\n");
        exit(EXIT_FAILURE);
    }

    int port = atoi(argv[1]);

    if (serv_socket<0){
        perror("Socket UDP creation failed\n");
        exit(EXIT_FAILURE);
    }

    printf("Socket Serveur : %d\n", serv_socket);
    printf("Port Serveur : %d\n", port);

    setsockopt(serv_socket, SOL_SOCKET, SO_REUSEADDR, &reuse, sizeof(reuse));

    memset((char*)&serv_addr_2,0,sizeof(serv_addr_2));
    serv_addr_2.sin_family = AF_INET;
    serv_addr_2.sin_port = htons(port);
    serv_addr_2.sin_addr.s_addr = INADDR_ANY;

    if(bind(serv_socket, (struct sockaddr *)&serv_addr_2,sizeof(serv_addr_2))<0){
        perror("Bind UDP failed");
        exit(EXIT_FAILURE);
    }

    socklen_t tailleaddr = sizeof(client_addr);
    while (1){
        int serv_socket_data = SYNC(serv_socket, &client_addr, tailleaddr, portV);
        if (serv_socket_data !=-1){
            printf("Connection established\n");
        }
        recvData(serv_socket_data, &client_addr, tailleaddr, portV);
        portV++;

        close(serv_socket_data);
            
            

            
    }

    close(serv_socket);




}