AFAIK, underscores are forbidden from being part of a host name as per
RFC 1123 Sec 2.1/RFC 952 (Assummptions Sec 1)
It's also spelled out in RFC 3986:
"
A registered name intended for lookup in the DNS (...)
consists of a sequence of domain labels separated by ".",
each domain label starting and ending with an alphanumeric character
and possibly also containing "-" characters.
"
Issac
On 2/2/2017 2:53 PM, Joe Orton wrote:
Another 2.4.25 regression reported from a Fedora user is that
underscores in hostnames are rejected by default now. I couldn't see a
specific discussion of this, was it deliberate?
Following breadcrumbs...
https://tools.ietf.org/html/rfc7230#section-5.4
Host = uri-host [ ":" port ] ; Section 2.7.1
https://tools.ietf.org/html/rfc7230#section-2.7
uri-host = <host, see [RFC3986], Section 3.2.2>
https://tools.ietf.org/html/rfc3986#section-3.2.2
host = IP-literal / IPv4address / reg-name
...
reg-name = *( unreserved / pct-encoded / sub-delims )
https://tools.ietf.org/html/rfc3986#section-2.3
unreserved = ALPHA / DIGIT / "-" / "." / "_" / "~"
From google I can see that _ in hostnames has various issues, so I'm not
sure what is right here. It's simple enough to relax the check, seems
unlikely allowing ~ is a good idea.
Index: server/vhost.c
===================================================================
--- server/vhost.c (revision 1781359)
+++ server/vhost.c (working copy)
@@ -757,7 +757,10 @@
int is_dotted_decimal = 1, leading_zeroes = 0, dots = 0;
for (ch = host; *ch; ch++) {
- if (apr_isalpha(*ch) || *ch == '-') {
+ /* This should allow any character in 'uri-host' per RFC
+ * 7320s5.4, which is 'host' by RFC 3986, which matches any
+ * 'unreserved' character. */
+ if (apr_isalpha(*ch) || *ch == '-' || *ch == '_') {
is_dotted_decimal = 0;
}
else if (ch[0] == '.') {
