DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 10E72384780D
Message-ID: <1f5c0302c156c9391d294ea9df84d93b8742a500.camel@posteo.net>
Subject: calls to socket() fail when calling getaddrinfo() with IPPROTO_TCP
To: cygwin@cygwin.com
Date: Thu, 29 Jul 2021 22:41:30 +0000
MIME-Version: 1.0
From: John Scott via Cygwin <cygwin@cygwin.com>
Reply-To: John Scott <jscott@posteo.net>
Content-Type: multipart/mixed; boundary="===============7042071369473644236=="
Sender: "Cygwin" <cygwin-bounces+archive-cygwin=delorie.com@cygwin.com>


--===============7042071369473644236==
Content-Type: multipart/signed; micalg="pgp-sha512";
	protocol="application/pgp-signature"; boundary="=-kHAtm/0iVaHTPFWjeQA0"


--=-kHAtm/0iVaHTPFWjeQA0
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

Hi,

I was wondering why my daytime server doesn't work when built for
Cygwin, and I have been able to narrow it down to this reproducible
test case:

#define _POSIX_C_SOURCE 200809L
#include <errno.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <unistd.h>

int main(void) {
	struct addrinfo *res;
	int s =3D getaddrinfo(NULL, "daytime", &(const struct addrinfo){.ai_flags =
=3D AI_PASSIVE, .ai_protocol =3D IPPROTO_TCP}, &res);
	if(s) {
		fprintf(stderr, "Failed to get address info: %s\n", (s !=3D EAI_SYSTEM) ?=
 gai_strerror(s) : strerror(errno));
		exit(EXIT_FAILURE);
	}

	for(const struct addrinfo *tmp =3D res; tmp; tmp =3D tmp->ai_next) {
		int fd =3D socket(tmp->ai_family, tmp->ai_socktype, tmp->ai_protocol);
		if(fd =3D=3D -1) {
			perror("Failed to create socket");
		} else if(close(fd) =3D=3D -1) {
			perror("Failed to close socket");
		}
	}
	freeaddrinfo(res);
}

This code fails with "Failed to create socket: Invalid argument". Does
anyone have an idea why this happens, given that the arguments to
socket() come directly from the call to getaddrinfo()? Remarkably,
changing the service from "daytime" to "http" seems to fix it, which
seems quite strange.

I'm not subscribed, so please CC me on replies.

--=-kHAtm/0iVaHTPFWjeQA0
Content-Type: application/pgp-signature; name="signature.asc"
Content-Description: This is a digitally signed message part
Content-Transfer-Encoding: 7bit

-----BEGIN PGP SIGNATURE-----

iIgEABYKADAWIQT287WtmxUhmhucNnhyvHFIwKstpwUCYQMumxIcanNjb3R0QHBv
c3Rlby5uZXQACgkQcrxxSMCrLacqfAEAn42r9/urCdv7GYK/eXlHRRdcuP8QE9Xl
v1OfgwAOOJcBAISTAPUYYg60A0gJ4Y+q3zTWxSV7Uyforbq9NNb/8BcH
=H7UE
-----END PGP SIGNATURE-----

--=-kHAtm/0iVaHTPFWjeQA0--


--===============7042071369473644236==
Content-Type: text/plain; charset="us-ascii"
MIME-Version: 1.0
Content-Transfer-Encoding: 7bit
Content-Disposition: inline


-- 
Problem reports:      https://cygwin.com/problems.html
FAQ:                  https://cygwin.com/faq/
Documentation:        https://cygwin.com/docs.html
Unsubscribe info:     https://cygwin.com/ml/#unsubscribe-simple

--===============7042071369473644236==--