Dotaz: inet_pton IPv4/IPv6

[miso]

Zdravim,

rad by som dosiahol nasledovne:

vstup: IPv4 adresa (10.20.30.40)

vystup: IPv4 adresa v tvare IPv6 (::ffff:10.20.30.40) tak, ako je uvedene v priklade napr. tu

Je to vobec mozne pomocou funkcie inet_pton? Zaujima ma to ciste zo zvedavosti, pokial to nejde, workaround nepotrebujem.

Nasledujuci kod vypise IPv4 adresu v "klasickom" IPv6 tvare (xxxx:xxxx:xxxx:xxxx:xxxx:xxxx), teda nezmyselnu adresu:

#include < sys/socket.h >
#include < netinet/in.h >
#include < arpa/inet.h >
#include < stdio.h >
#include < stdlib.h >

int main(int argc, char *argv[])
{
    struct in_addr addr;
    unsigned char buf[sizeof(struct in6_addr)];
    char str[INET6_ADDRSTRLEN];

    if (argc<2)
    {
        fprintf(stderr, "IPv4 address required as an argument.\n");
        exit(EXIT_FAILURE);
    }
    if (inet_aton(argv[1], &addr) == 0)
    {
        perror("inet_aton");
        exit(EXIT_FAILURE);
    }
    if (inet_pton(AF_INET, argv[1], buf) != 1)
    {
        perror("inet_pton");
        exit(EXIT_FAILURE);
    }
    if (inet_ntop(AF_INET6, buf, str, INET6_ADDRSTRLEN)==NULL)
    {
        perror("inet_ntop");
        exit(EXIT_FAILURE);
    }
    printf("%s\n", str);
    exit(EXIT_SUCCESS);
}

---

---

Odpovědi

[miso]

Vyriesil som to nasledovne:

#define _GNU_SOURCE
#include < string.h>
#include < sys/socket.h>
#include < netinet/in.h>
#include < arpa/inet.h>
#include < stdio.h>
#include < stdlib.h>

#define IPV6_ADDRESS_SIZE sizeof(struct in6_addr)

int main(int argc, char *argv[])
{
    struct in_addr addr;
    unsigned char buf_v4[sizeof(struct in_addr)];
    unsigned char buf_v6[IPV6_ADDRESS_SIZE] = {0};
    unsigned char str[INET6_ADDRSTRLEN];

    if (argc<2)
    {
        fprintf(stderr, "IPv4 address required as an argument.\n");
        exit(EXIT_FAILURE);
    }

    if (inet_aton(argv[1], &addr) == 0)
    {
        perror("inet_aton");
        exit(EXIT_FAILURE);
    }

    if (inet_pton(AF_INET, argv[1], buf_v4) != 1)
    {
        perror("inet_pton");
        exit(EXIT_FAILURE);
    }

    *(buf_v6 + IPV6_ADDRESS_SIZE - 5) = 255;
    *(buf_v6 + IPV6_ADDRESS_SIZE - 6) = 255;
    mempcpy(buf_v6 + IPV6_ADDRESS_SIZE - 4, buf_v4, 4);

    if (inet_ntop(AF_INET6, buf_v6, str, INET6_ADDRSTRLEN)==NULL)
    {
        perror("inet_ntop");
        exit(EXIT_FAILURE);
    }

    printf("%s\n", str);
    exit(EXIT_SUCCESS);
}