From 5fa2efa74543436e7a23d1154bdea41e58f8d242 Mon Sep 17 00:00:00 2001
From: Martin Stein <martin.stein@genode-labs.com>
Date: Fri, 30 Apr 2021 17:03:00 +0200
Subject: [PATCH] net/dhcp: print readable message types

When a DHCP packet is printed out, it first tries to determine the most
specific message type from the DHCP options and print its human-readable name
right after the protocol name. If finding the message type fails, the less
specific opcode is printed instead, but also in a human-readable way.

Fixes #4131
---
 repos/os/src/lib/net/dhcp.cc | 54 ++++++++++++++++++++++++++++++++++--
 1 file changed, 52 insertions(+), 2 deletions(-)

diff --git a/repos/os/src/lib/net/dhcp.cc b/repos/os/src/lib/net/dhcp.cc
index 2f9567617e..afb1060223 100644
--- a/repos/os/src/lib/net/dhcp.cc
+++ b/repos/os/src/lib/net/dhcp.cc
@@ -15,9 +15,59 @@
 #include <net/dhcp.h>
 #include <base/output.h>
 
+using namespace Genode;
+
+using Message_type = Net::Dhcp_packet::Message_type;
+
+
+static char const *msg_type_to_string(Message_type type)
+{
+	switch (type) {
+	case Message_type::DISCOVER: return "DISCOVER";
+	case Message_type::OFFER   : return "OFFER";
+	case Message_type::REQUEST : return "REQUEST";
+	case Message_type::DECLINE : return "DECLINE";
+	case Message_type::ACK     : return "ACK";
+	case Message_type::NAK     : return "NAK";
+	case Message_type::RELEASE : return "RELEASE";
+	case Message_type::INFORM  : return "INFORM";
+	}
+	class Never_reached { };
+	throw Never_reached { };
+}
+
+
+static char const *opcode_to_string(uint8_t op)
+{
+	switch (op) {
+	case 1:  return "REPLY";
+	case 2:  return "REQUEST";
+	default: return "?";
+	}
+	class Never_reached { };
+	throw Never_reached { };
+}
+
 
 void Net::Dhcp_packet::print(Genode::Output &output) const
 {
-	Genode::print(output, "\033[32mDHCP\033[0m ", client_mac(),
-	              " > ", siaddr(), " cmd ", op());
+	bool msg_type_found { false };
+	for_each_option([&] (Option const &opt) {
+
+		if (opt.code() == Option::Code::MSG_TYPE) {
+
+			msg_type_found = true;
+			Message_type_option const &msg_type {
+				*reinterpret_cast<Message_type_option const *>(&opt) };
+
+			Genode::print(output, "\033[32mDHCP ",
+			              msg_type_to_string(msg_type.value()), "\033[0m ",
+			              client_mac(), " > ", siaddr());
+		}
+	});
+	if (!msg_type_found) {
+
+		Genode::print(output, "\033[32mDHCP ", opcode_to_string(op()),
+		              "\033[0m ", client_mac(), " > ", siaddr());
+	}
 }