getaddrinfo returning error -2 while fetching ipv6 (getaddrinfo: Name or service not known)

Question

I am trying to write a client-server program for ipv6. I am facing issue when I am trying to call getaddrinfo function. It returns -2 (getaddrinfo: Name or service not known).

This works fine on Windows system, but fails on Linux.

$ ifconfig |grep inet6
inet6 fe80::e41b:2c23:a286:77a  prefixlen 64  scopeid 0x20<link>
inet6 ::1  prefixlen 128  scopeid 0x10<host>

ifconfig says ipv6 is enabled. Even i can ping6 this ip from another host.

#include <iostream>
#include <string.h>
#include <netdb.h>
#include <arpa/inet.h>

int main(int argc, char** argv)
{
    addrinfo hints = {}, *results, *res;
    memset(&hints, 0, sizeof(hints));
    hints.ai_family = AF_INET6;
    hints.ai_socktype = SOCK_STREAM;
    hints.ai_protocol = IPPROTO_TCP;

    int m = getaddrinfo(argv[1], "2019", &hints, &results);
    if (m < 0)
    {
        std::cout << "getaddrinfo : " << gai_strerror(m) << std::endl;
        return 1;
    }

    for(res = results; res != NULL; res = res->ai_next)
    {
        char straddr[INET6_ADDRSTRLEN] = {};
        if (inet_ntop(res->ai_family, &(reinterpret_cast<sockaddr_in6*>(res->ai_addr)->sin6_addr), straddr, sizeof(straddr)))
            std::cout << "IP - " << straddr << "\n";
        else
            std::cout << "inet_ntop error";
    }

    freeaddrinfo(results);

    return 0;
}

It is expected to print the ip in v6 format but it prints getaddrinfo: Name or service not known

Possible duplicate of [C Socket Error: "Name or service not known"](https://stackoverflow.com/questions/25519529/c-socket-error-name-or-service-not-known) — Btc Sources, Jan 04 '19 at 10:21
Works for me (on Linux). Did you try to set ```hints.ai_flags = AI_NUMERICSERV;```? — grungegurunge, Jan 04 '19 at 10:23
Do you use different nameservers under linux and windows? (please really check) — Ctx, Jan 04 '19 at 10:32
(as a side note: you seem to think, that ipv6 has to be enabled for resolving ipv6-addresses; this is not necessarily true, you can resolve ipv6 addresses with ipv4-dns-queries, this is indeed probably the most common case) — Ctx, Jan 04 '19 at 10:35
Knowing what a piece of garbage getaddrinfo code is, I would assume that this problem could depend on glibc version you work with. Could you specify it? — grungegurunge, Jan 04 '19 at 11:35

getaddrinfo returning error -2 while fetching ipv6 (getaddrinfo: Name or service not known)

0 Answers0