Subject: [PATCH] services: networking: Add netmask to loopback address.

From: Ludovic Courtès <[email-masked]>
Date: Thu, 6 Jan 2022 10:46:03 +0100

From: Ludovic Courtès <[email-masked]>

Previously, we would get a fishy 127.0.0.1/0 interface:

  $ ip a show dev lo
  1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
      link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
      inet 127.0.0.1/8 scope host lo
	 valid_lft forever preferred_lft forever
      inet 127.0.0.1/0 scope global lo
	 valid_lft forever preferred_lft forever
      inet6 ::1/128 scope host
	 valid_lft forever preferred_lft forever

With this change, we get nothing but the "/8" version:

  $ ip a show dev lo
  1: lo: <LOOPBACK,MULTICAST,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
      link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
      inet 127.0.0.1/8 scope global lo
	 valid_lft forever preferred_lft forever
      inet6 ::1/128 scope host
	 valid_lft forever preferred_lft forever

Reported by Yann Dupont <[email-masked]>.

* gnu/services/base.scm (assert-valid-address): Remove special cases for
127.0.0.1 and ::1.
(%loopback-static-networking): Add "/8".
---
 gnu/services/base.scm | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/gnu/services/base.scm b/gnu/services/base.scm
index 88869e40d2..e46bb591a9 100644
--- a/gnu/services/base.scm
+++ b/gnu/services/base.scm
@@ -1,5 +1,5 @@
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020, 2021 Ludovic Courtès <[email-masked]>
+;;; Copyright © 2013-2022 Ludovic Courtès <[email-masked]>
 ;;; Copyright © 2015, 2016 Alex Kost <[email-masked]>
 ;;; Copyright © 2015, 2016, 2020 Mark H Weaver <[email-masked]>
 ;;; Copyright © 2015 Sou Bunnbu <[email-masked]>
@@ -2393,11 +2393,7 @@ (define (ipv6-address? str)
 
 (define-compile-time-procedure (assert-valid-address (address string?))
   "Ensure ADDRESS has a valid netmask."
-  (unless (or (cidr->netmask address)
-              (and=> (false-if-exception (inet-pton AF_INET address))
-                     (cut = INADDR_LOOPBACK <>))
-              (and=> (false-if-exception (inet-pton AF_INET6 address))
-                     (cut = 1 <>)))
+  (unless (cidr->netmask address)
     (raise
      (make-compound-condition
       (formatted-message (G_ "address '~a' lacks a network mask")
@@ -2741,7 +2737,7 @@ (define %loopback-static-networking
   (static-networking
    (addresses (list (network-address
                      (device "lo")
-                     (value "127.0.0.1"))))
+                     (value "127.0.0.1/8"))))
    (requirement '())
    (provision '(loopback))))

base-commit: 97657689507a0681aa9699407d292383ff22c330
-- 
2.33.0