From e4fabffe740800d2ad9ded4aec4b768485289653 Mon Sep 17 00:00:00 2001
From: Christian Breunig <christian@breunig.cc>
Date: Tue, 3 Oct 2023 18:14:23 +0200
Subject: pppoe: T5630: allow to specify MRU in addition to already
 configurable MTU

Set the MRU (Maximum Receive Unit) value to n. PPPd will ask the peer to send
packets of no more than n bytes. The value of n must be between 128 and 16384,
the default was always 1492 to match PPPoE MTU.

A value of 296 works well on very slow links (40 bytes for TCP/IP header + 256
bytes of data). Note that for the IPv6 protocol, the MRU must be at least 1280.

CLI:
  set interfaces pppoe pppoe0 mru 1280
(cherry picked from commit e062a8c11856f213983f5b41f50d4f9dbc0dde0f)
---
 data/templates/pppoe/peer.j2                   |  2 +-
 interface-definitions/interfaces-pppoe.xml.in  | 14 ++++++++++++++
 smoketest/scripts/cli/test_interfaces_pppoe.py |  4 ++++
 3 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/data/templates/pppoe/peer.j2 b/data/templates/pppoe/peer.j2
index f30cefe63..2a99fcb2a 100644
--- a/data/templates/pppoe/peer.j2
+++ b/data/templates/pppoe/peer.j2
@@ -50,7 +50,7 @@ ifname {{ ifname }}
 ipparam {{ ifname }}
 debug
 mtu {{ mtu }}
-mru {{ mtu }}
+mru {{ mru }}
 
 {% if authentication is vyos_defined %}
 {{ 'user "' + authentication.username + '"' if authentication.username is vyos_defined }}
diff --git a/interface-definitions/interfaces-pppoe.xml.in b/interface-definitions/interfaces-pppoe.xml.in
index b78f92c85..30fcb8573 100644
--- a/interface-definitions/interfaces-pppoe.xml.in
+++ b/interface-definitions/interfaces-pppoe.xml.in
@@ -109,6 +109,20 @@
           <leafNode name="mtu">
             <defaultValue>1492</defaultValue>
           </leafNode>
+          <leafNode name="mru">
+            <properties>
+              <help>Maximum Receive Unit (MRU)</help>
+              <valueHelp>
+                <format>u32:128-16384</format>
+                <description>Maximum Receive Unit in byte</description>
+              </valueHelp>
+              <constraint>
+                <validator name="numeric" argument="--range 128-16384"/>
+              </constraint>
+              <constraintErrorMessage>MRU must be between 128 and 16384</constraintErrorMessage>
+            </properties>
+            <defaultValue>1492</defaultValue>
+          </leafNode>
           #include <include/interface/no-peer-dns.xml.i>
           <leafNode name="remote-address">
             <properties>
diff --git a/smoketest/scripts/cli/test_interfaces_pppoe.py b/smoketest/scripts/cli/test_interfaces_pppoe.py
index 0ce5e2fe0..0685833fb 100755
--- a/smoketest/scripts/cli/test_interfaces_pppoe.py
+++ b/smoketest/scripts/cli/test_interfaces_pppoe.py
@@ -59,10 +59,12 @@ class PPPoEInterfaceTest(VyOSUnitTestSHIM.TestCase):
             user = f'VyOS-user-{interface}'
             passwd = f'VyOS-passwd-{interface}'
             mtu = '1400'
+            mru = '1300'
 
             self.cli_set(base_path + [interface, 'authentication', 'username', user])
             self.cli_set(base_path + [interface, 'authentication', 'password', passwd])
             self.cli_set(base_path + [interface, 'mtu', mtu])
+            self.cli_set(base_path + [interface, 'mru', mru])
             self.cli_set(base_path + [interface, 'no-peer-dns'])
 
             # check validate() - a source-interface is required
@@ -80,6 +82,8 @@ class PPPoEInterfaceTest(VyOSUnitTestSHIM.TestCase):
 
             tmp = get_config_value(interface, 'mtu')[1]
             self.assertEqual(tmp, mtu)
+            tmp = get_config_value(interface, 'mru')[1]
+            self.assertEqual(tmp, mru)
             tmp = get_config_value(interface, 'user')[1].replace('"', '')
             self.assertEqual(tmp, user)
             tmp = get_config_value(interface, 'password')[1].replace('"', '')
-- 
cgit v1.2.3