daniel:// stenberg://Mar 10, 2025

Inconsistent octal madness

$ ping 010
PING 010 (0.0.0.8) 56(84) bytes of data.
$ ping 010.1.1.1
PING 010.1.1.1 (8.1.1.1) 56(84) bytes of data.
$ ping 018
ping: 018: Name or service not known
$ ping 18
PING 18 (0.0.0.18) 56(84) bytes of data.
$ ping 018.1.1.1
PING 018.1.1.1 (18.1.1.1) 56(84) bytes of data.
$ ping 18.1.1.1
PING 18.1.1.1 (18.1.1.1) 56(84) bytes of data.

Show threaddaniel:// stenberg://
ok sorry, embarrassingly enough it was misdiagnosed by me. It is my silly DNS server that "helpfully" resolves these names for me!
Mar 10, 2025 at 3:34pmWeb
Show threadDavid WheelerMar 10, 2025
@bagder
Show threadHarry SintonenMar 10, 2025
@bagder
Show threadUpCloudMar 10, 2025
@bagder
Show threadAuthor Hester VelmansMar 10, 2025
@bagder
No worries at all! DNS issues can be sneaky like that. Glad you figured it out!
Show threadKoos van den HoutMar 10, 2025

@bagder I'm not sure it's DNS, it could be earlier in the local functions to handle IP addresses in different notations (I am not going to embarrass myself by naming these functions to you).

That will make things like

$ ping 0x7f000001
PING 0x7f000001 (127.0.0.1) 56(84) bytes of data.

$ ping 0177.0.0.1
PING 0177.0.0.1 (127.0.0.1) 56(84) bytes of data.

work without ever hitting the resolver.

Show threadjerMar 10, 2025

@KHoos @bagder

Even those "local functions" are part of "the resolver".

(Back when I did some professional tooling and troubleshooting, I couldn't stress enough to my colleagues that PING is the worst possible way to "find out" things about internet connections. Instead, use #curl and fetch an HTTPS domain for a site that actually interests you.)

Show threaddaniel:// stenberg://Mar 10, 2025

@KHoos I am sure it is the DNS. Using ltrace I could see how 018.1.1.1 gets a 0 back from the getaddrinfo() call. I can also reproduce it with dig directly.

The precise point was to use 018 as the first number, as that is 0-prefixed but not a valid octal.

Show threadRobert EdmondsMar 10, 2025

@bagder All of those except 018.1.1.1 get resolved directly by the OS for me.

root@592cda340524:/# cat /etc/os-release
PRETTY_NAME="Debian GNU/Linux trixie/sid"
NAME="Debian GNU/Linux"
VERSION_CODENAME=trixie
ID=debian
HOME_URL="https://www.debian.org/"
SUPPORT_URL="https://www.debian.org/support"
BUG_REPORT_URL="https://bugs.debian.org/"
root@592cda340524:/# grep hosts: /etc/nsswitch.conf
hosts: files
root@592cda340524:/# getent ahosts 010
0.0.0.8 STREAM 010
0.0.0.8 DGRAM
0.0.0.8 RAW
root@592cda340524:/# getent ahosts 010.1.1.1
8.1.1.1 STREAM 010.1.1.1
8.1.1.1 DGRAM
8.1.1.1 RAW
root@592cda340524:/# getent ahosts 018
root@592cda340524:/# echo $?
2
root@592cda340524:/# getent ahosts 18
0.0.0.18 STREAM 18
0.0.0.18 DGRAM
0.0.0.18 RAW
root@592cda340524:/# getent ahosts 018.1.1.1
root@592cda340524:/# echo $?
2
root@592cda340524:/# getent ahosts 18.1.1.1
18.1.1.1 STREAM 18.1.1.1
18.1.1.1 DGRAM
18.1.1.1 RAW
root@592cda340524:/#

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Show threadPetr Menšík Mar 10, 2025
@bagder which DNS server/cache converts names to IP address this way?
Show threaddaniel:// stenberg://Mar 10, 2025
@pemensik I did not dig very deep. The closest is my ASUS router's DNS, I didn't check if it is this or next hop that does this craziness. Doesn't matter to me.
Show threadPetr Menšík Mar 10, 2025
@bagder can you send "dig ch txt version.bind" query to it? I expect Dnsmasq of sort. inet_pton() accepts only well specified addresses. inet_aton() accepted almost any random garbage and should be avoided and replaced. Is it possible your ping uses the old call?
Show threaddaniel:// stenberg://Mar 10, 2025
@pemensik this is a very recent ping and glibc. As you can see in the thread, all pings on all platforms work like this too - except for the name my DNS tricked me to misunderstand.
Show threadPetr Menšík Mar 10, 2025
@bagder ooh. At least python socket module considers getaddrinfo ('127.1', 0, flags=AI_NUMERICHOST) or even '0x7f.1' as completely valid thing. Expected such legacy crap would get refused, but getaddrinfo does not enforce full IPv4.
Show threadJim FullerMar 11, 2025
@bagder if it helps - I spent an entire day finding out I had misplaced a semi colon in rust the other day ... oh how our AI spawn will laugh at our follies ...