our_utils.c

#include <arpa/inet.h>
#include <errno.h>
#include <fcntl.h>
#include <netdb.h>
#include <netinet/in.h>
#include <poll.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <unistd.h>

#include "log.h"
#include "our_utils.h"

const char * real_address(const char *address, struct sockaddr_in6 *rval)
{
    struct addrinfo hints;
    struct addrinfo *result; 
    memset(&hints, 0, sizeof(hints));
    hints.ai_family = AF_INET6;     
    hints.ai_socktype = SOCK_DGRAM;
    hints.ai_flags  = AI_CANONNAME; 
    hints.ai_protocol = 0;
    int res = getaddrinfo(address, NULL, &hints, &result);
    if ( res != 0 )
        return gai_strerror(res);
    rval = (struct sockaddr_in6 *) memcpy( (void *) rval, result->ai_addr, sizeof(struct sockaddr_in6));
    freeaddrinfo(result);
    return NULL;
}


void ipv6_to_str_unexpanded(char *str, const struct in6_addr *addr) {
   sprintf(str, "%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x",
                 (int)addr->s6_addr[0], (int)addr->s6_addr[1],
                 (int)addr->s6_addr[2], (int)addr->s6_addr[3],
                 (int)addr->s6_addr[4], (int)addr->s6_addr[5],
                 (int)addr->s6_addr[6], (int)addr->s6_addr[7],
                 (int)addr->s6_addr[8], (int)addr->s6_addr[9],
                 (int)addr->s6_addr[10], (int)addr->s6_addr[11],
                 (int)addr->s6_addr[12], (int)addr->s6_addr[13],
                 (int)addr->s6_addr[14], (int)addr->s6_addr[15]);
}


int create_socket_bind(struct sockaddr_in6 * source_addr)
{
    // TODO: Create a IPv6 socket supporting datagrams
    int sock = socket(AF_INET6, SOCK_DGRAM, 0);
    // TODO: Bind it to the source
    int err  = bind(sock, (struct sockaddr *) source_addr, sizeof(struct sockaddr_in6));
    if (err == -1) 
        return -1;

    char text[100];
    ipv6_to_str_unexpanded(text, &(source_addr->sin6_addr));
    //const char * addr_str = inet_ntop(AF_INET6, (void *) &(source_addr->sin6_addr), text, 100);
    DEBUG("Successfully bound to IPv6 address : %s, port : %d", text, ntohs(source_addr->sin6_port));
    return sock;
}


int create_socket_connect(struct sockaddr_in6 * dest_addr)
{
    int sock = socket(AF_INET6, SOCK_DGRAM, 0);
    int err  = connect(sock, (struct sockaddr *) dest_addr, sizeof(*dest_addr));
    if (err == -1) 
        return -1;
    char text[100];
    ipv6_to_str_unexpanded(text, &(dest_addr->sin6_addr));
    DEBUG("Successfully connected to IPv6 addresss: %s, port : %d", text, ntohs(dest_addr->sin6_port));
    return sock;
}


int create_socket(struct sockaddr_in6 *source_addr, int src_port, struct sockaddr_in6 *dest_addr, int dst_port)
{
    if ( source_addr != NULL && dest_addr == NULL )
    {
        source_addr->sin6_port = htons(src_port);
        return create_socket_bind(source_addr);
    } else if ( source_addr == NULL && dest_addr != NULL ){
        dest_addr->sin6_port   = htons(dst_port);
        return create_socket_connect(dest_addr);
    }
    return -1;
}

int wait_for_client(int sfd)
{
    int MAX_MESSAGE_SIZE = 1024;
    uint8_t buff[MAX_MESSAGE_SIZE];   // allocate the receive buffer on the stack
    struct sockaddr_storage peer_addr;  // allocate the peer's address on the stack. It will be initialized when we receive a message
    socklen_t peer_addr_len = sizeof(struct sockaddr_storage); // variable that will contain the length of the peer's address
    ssize_t amount_read = recvfrom(sfd, buff, MAX_MESSAGE_SIZE, MSG_PEEK, (struct sockaddr *) &peer_addr, &peer_addr_len);
    if (amount_read == -1){ 
        return -1;
    }
    int err             = connect(sfd, (struct sockaddr *) &peer_addr, sizeof(struct sockaddr_storage));
    if (err != EISCONN && err != 0)
        return -1;
    char text[100];
    struct sockaddr_in6 * cast = (struct sockaddr_in6 *) &peer_addr;
    ipv6_to_str_unexpanded(text, &(cast->sin6_addr));
    DEBUG("Successfully connected to IPv6 addresss: %s, port : %d", text, ntohs(cast->sin6_port));
    return 0;
}