On Mon, Feb 05, 2018 at 12:56:47PM +0100,
Vladimír Čunát <vladimir.cunat+i...@nic.cz> wrote
a message of 8 lines which said:
> Current Firefox 58.0.1 and old Chromium 61.0.3163.79, Linux, same
> result. The system resolver does fetch _www.ksk-test.net. OK. (I
> can't say I understand what happens.)
Isn't is simply because some browsers rely on the standard library's
getaddrinfo() and this routine does not accept all domain names? On Linux:
#define alphachar(c) (((c) >= 0x41 && (c) <= 0x5a) \
|| ((c) >= 0x61 && (c) <= 0x7a))
#define digitchar(c) ((c) >= 0x30 && (c) <= 0x39)
#define borderchar(c) (alphachar(c) || digitchar(c))
#define middlechar(c) (borderchar(c) || hyphenchar(c) || underscorechar(c))
#define domainchar(c) ((c) > 0x20 && (c) < 0x7f)
int
res_hnok(const char *dn) {
int pch = PERIOD, ch = *dn++;
while (ch != '\0') {
int nch = *dn++;
if (periodchar(ch)) {
(void)NULL;
} else if (periodchar(pch)) {
if (!borderchar(ch))
return (0);
} else if (periodchar(nch) || nch == '\0') {
if (!borderchar(ch))
return (0);
} else {
if (!middlechar(ch))
return (0);
}
pch = ch, ch = nch;
}
return (1);
}
Underscores are not accepted at the beginning of a name.
% dig +short +nodnssec _www.ksk-test.net
ron.kumari.net.
204.194.23.4
% ping _www.ksk-test.net
ping: _www.ksk-test.net: Name or service not known
If you want to check on FreeBSD, it's here:
https://svnweb.freebsd.org/base/head/lib/libc/net/gethostbydns.c?view=markup#l140
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