From 64647edbe1f0712a173a73896f270f6bf6ae6065 Mon Sep 17 00:00:00 2001
From: Max Kellermann <max.kellermann@gmail.com>
Date: Tue, 19 Sep 2023 11:17:48 +0200
Subject: [PATCH] lib/fmt/SocketAddressFormatter: new library

---
 src/client/New.cxx                     |  7 +++----
 src/event/ServerSocket.cxx             | 18 +++++++-----------
 src/lib/fmt/SocketAddressFormatter.hxx | 21 +++++++++++++++++++++
 test/run_resolver.cxx                  |  6 ++++--
 4 files changed, 35 insertions(+), 17 deletions(-)
 create mode 100644 src/lib/fmt/SocketAddressFormatter.hxx

diff --git a/src/client/New.cxx b/src/client/New.cxx
index b4d65ab62..d3df5158b 100644
--- a/src/client/New.cxx
+++ b/src/client/New.cxx
@@ -8,9 +8,9 @@
 #include "BackgroundCommand.hxx"
 #include "Partition.hxx"
 #include "Instance.hxx"
+#include "lib/fmt/SocketAddressFormatter.hxx"
 #include "net/UniqueSocketDescriptor.hxx"
 #include "net/SocketAddress.hxx"
-#include "net/ToString.hxx"
 #include "Log.hxx"
 #include "Version.h"
 
@@ -36,11 +36,10 @@ Client::Client(EventLoop &_loop, Partition &_partition,
 
 void
 client_new(EventLoop &loop, Partition &partition,
-	   UniqueSocketDescriptor fd, SocketAddress address, int uid,
+	   UniqueSocketDescriptor fd, SocketAddress remote_address, int uid,
 	   unsigned permission) noexcept
 {
 	static unsigned int next_client_num;
-	const auto remote = ToString(address);
 
 	assert(fd.IsDefined());
 
@@ -61,7 +60,7 @@ client_new(EventLoop &loop, Partition &partition,
 	partition.clients.push_back(*client);
 
 	FmtInfo(client_domain, "[{}] opened from {}",
-		num, remote);
+		num, remote_address);
 }
 
 void
diff --git a/src/event/ServerSocket.cxx b/src/event/ServerSocket.cxx
index fff8e3e6e..2fcca8a7c 100644
--- a/src/event/ServerSocket.cxx
+++ b/src/event/ServerSocket.cxx
@@ -4,6 +4,7 @@
 #include "ServerSocket.hxx"
 #include "lib/fmt/ExceptionFormatter.hxx"
 #include "lib/fmt/RuntimeError.hxx"
+#include "lib/fmt/SocketAddressFormatter.hxx"
 #include "net/IPv4Address.hxx"
 #include "net/IPv6Address.hxx"
 #include "net/StaticSocketAddress.hxx"
@@ -13,7 +14,6 @@
 #include "net/UniqueSocketDescriptor.hxx"
 #include "net/Resolver.hxx"
 #include "net/AddressInfo.hxx"
-#include "net/ToString.hxx"
 #include "event/SocketEvent.hxx"
 #include "fs/AllocatedPath.hxx"
 #include "util/Domain.hxx"
@@ -83,9 +83,9 @@ public:
 		event.Close();
 	}
 
-	[[nodiscard]] [[gnu::pure]]
-	std::string ToString() const noexcept {
-		return ::ToString(address);
+	[[nodiscard]]
+	SocketAddress GetAddress() const noexcept {
+		return address;
 	}
 
 	void SetFD(UniqueSocketDescriptor _fd) noexcept {
@@ -224,23 +224,19 @@ ServerSocket::Open()
 			i.Open();
 		} catch (...) {
 			if (good != nullptr && good->GetSerial() == i.GetSerial()) {
-				const auto address_string = i.ToString();
-				const auto good_string = good->ToString();
 				FmtError(server_socket_domain,
 					 "bind to '{}' failed "
 					 "(continuing anyway, because "
 					 "binding to '{}' succeeded): {}",
-					 address_string,
-					 good_string,
+					 i.GetAddress(),
+					 good->GetAddress(),
 					 std::current_exception());
 			} else if (bad == nullptr) {
 				bad = &i;
 
-				const auto address_string = i.ToString();
-
 				try {
 					std::throw_with_nested(FmtRuntimeError("Failed to bind to '{}'",
-									       address_string));
+									       i.GetAddress()));
 				} catch (...) {
 					last_error = std::current_exception();
 				}
diff --git a/src/lib/fmt/SocketAddressFormatter.hxx b/src/lib/fmt/SocketAddressFormatter.hxx
new file mode 100644
index 000000000..14a133155
--- /dev/null
+++ b/src/lib/fmt/SocketAddressFormatter.hxx
@@ -0,0 +1,21 @@
+// SPDX-License-Identifier: BSD-2-Clause
+// author: Max Kellermann <max.kellermann@gmail.com>
+
+#pragma once
+
+#include "net/SocketAddress.hxx"
+#include "net/ToString.hxx"
+
+#include <fmt/format.h>
+
+#include <concepts>
+
+template<typename T>
+requires std::convertible_to<T, SocketAddress>
+struct fmt::formatter<T> : formatter<string_view>
+{
+	template<typename FormatContext>
+	auto format(SocketAddress address, FormatContext &ctx) {
+		return formatter<string_view>::format(ToString(address), ctx);
+	}
+};
diff --git a/test/run_resolver.cxx b/test/run_resolver.cxx
index c29c65a8a..02f834eed 100644
--- a/test/run_resolver.cxx
+++ b/test/run_resolver.cxx
@@ -1,12 +1,14 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
 // Copyright The Music Player Daemon Project
 
+#include "lib/fmt/SocketAddressFormatter.hxx"
 #include "net/Resolver.hxx"
 #include "net/AddressInfo.hxx"
-#include "net/ToString.hxx"
 #include "net/SocketAddress.hxx"
 #include "util/PrintException.hxx"
 
+#include <fmt/format.h>
+
 #include <exception>
 
 #include <stdio.h>
@@ -20,7 +22,7 @@ try {
 	}
 
 	for (const auto &i : Resolve(argv[1], 80, AI_PASSIVE, SOCK_STREAM)) {
-		printf("%s\n", ToString(i).c_str());
+		fmt::print("{}\n", i);
 	}
 
 	return EXIT_SUCCESS;