From 3fc29ed18ea46e83e2ba2d4b39e52239771f427c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Roman=20Smr=C5=BE?= <roman.smrz@seznam.cz>
Date: Sun, 7 May 2023 11:23:31 +0200
Subject: Network: use IPv6 socket internally

---
 src/main.cpp    |  3 +--
 src/network.cpp | 57 ++++++++++++++++++++++++++++++++++++++++-----------------
 src/network.h   |  6 +++---
 3 files changed, 44 insertions(+), 22 deletions(-)

(limited to 'src')

diff --git a/src/main.cpp b/src/main.cpp
index d0015c2..63b78dd 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -303,10 +303,9 @@ void startServer(const vector<string> &)
 		if (peer) {
 			if (i >= testPeers.size()) {
 				testPeers.push_back(TestPeer { .peer = *peer, .id = i + 1 });
-				const auto & paddr = peer->address();
 
 				ostringstream ss;
-				ss << prefix << " addr " << inet_ntoa(paddr.sin_addr) << " " << ntohs(paddr.sin_port);
+				ss << prefix << " addr " << peer->addressStr() << " " << peer->port();
 				printLine(ss.str());
 			}
 
diff --git a/src/network.cpp b/src/network.cpp
index 5c268ae..ecf7ca0 100644
--- a/src/network.cpp
+++ b/src/network.cpp
@@ -104,10 +104,7 @@ string Peer::name() const
 		if (holds_alternative<shared_ptr<WaitingRef>>(speer->identity))
 			return string(std::get<shared_ptr<WaitingRef>>(speer->identity)->ref.digest());
 
-		char buf[16];
-		if (inet_ntop(AF_INET, &speer->addr.sin_addr, buf, sizeof(buf)))
-			return string(buf) + ":" + to_string(ntohs(speer->addr.sin_port));
-		return "<invalid address>";
+		return addressStr();
 	}
 	return "<server closed>";
 }
@@ -120,13 +117,32 @@ optional<Identity> Peer::identity() const
 	return nullopt;
 }
 
-const sockaddr_in & Peer::address() const
+const sockaddr_in6 & Peer::address() const
 {
 	if (auto speer = p->speer.lock())
 		return speer->addr;
 	throw runtime_error("Server no longer running");
 }
 
+string Peer::addressStr() const
+{
+	char buf[INET6_ADDRSTRLEN];
+	const in6_addr & addr = address().sin6_addr;
+
+	if (inet_ntop(AF_INET6, &addr, buf, sizeof(buf))) {
+		if (IN6_IS_ADDR_V4MAPPED(&addr) && strncmp(buf, "::ffff:", 7) == 0)
+			return buf + 7;
+		return buf;
+	}
+
+	return "<invalid address>";
+}
+
+uint16_t Peer::port() const
+{
+	return ntohs(address().sin6_port);
+}
+
 void Peer::Priv::notifyWatchers()
 {
 	if (auto slist = list.lock()) {
@@ -242,11 +258,17 @@ Server::Priv::Priv(const Head<LocalState> & local, const Identity & self):
 			bcastAddresses.push_back(((sockaddr_in*)ifa->ifa_broadaddr)->sin_addr);
 		}
 	}
-	
-	sock = socket(AF_INET, SOCK_DGRAM, 0);
+
+	sock = socket(AF_INET6, SOCK_DGRAM, 0);
 	if (sock < 0)
 		throw std::system_error(errno, std::generic_category());
 
+	int disable = 0;
+	// Should be disabled by default, but try to make sure. On platforms
+	// where the calls fails, IPv4 might not work.
+	setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY,
+				&disable, sizeof(disable));
+
 	int enable = 1;
 	if (setsockopt(sock, SOL_SOCKET, SO_BROADCAST,
 				&enable, sizeof(enable)) < 0)
@@ -256,9 +278,9 @@ Server::Priv::Priv(const Head<LocalState> & local, const Identity & self):
 				&enable, sizeof(enable)) < 0)
 		throw std::system_error(errno, std::generic_category());
 
-	sockaddr_in laddr = {};
-	laddr.sin_family = AF_INET;
-	laddr.sin_port = htons(discoveryPort);
+	sockaddr_in6 laddr = {};
+	laddr.sin6_family = AF_INET6;
+	laddr.sin6_port = htons(discoveryPort);
 	if (::bind(sock, (sockaddr *) &laddr, sizeof(laddr)) < 0)
 		throw std::system_error(errno, std::generic_category());
 
@@ -296,7 +318,7 @@ void Server::Priv::doListen()
 	unique_lock lock(dataMutex);
 
 	for (; !finish; lock.lock()) {
-		sockaddr_in paddr;
+		sockaddr_in6 paddr;
 
 		lock.unlock();
 		socklen_t addrlen = sizeof(paddr);
@@ -390,16 +412,17 @@ void Server::Priv::doAnnounce()
 	}
 }
 
-bool Server::Priv::isSelfAddress(const sockaddr_in & paddr)
+bool Server::Priv::isSelfAddress(const sockaddr_in6 & paddr)
 {
-	for (const auto & in : localAddresses)
-		if (in.s_addr == paddr.sin_addr.s_addr &&
-				ntohs(paddr.sin_port) == discoveryPort)
-			return true;
+	if (IN6_IS_ADDR_V4MAPPED(&paddr.sin6_addr))
+		for (const auto & in : localAddresses)
+			if (in.s_addr == *reinterpret_cast<const in_addr_t*>(paddr.sin6_addr.s6_addr + 12) &&
+					ntohs(paddr.sin6_port) == discoveryPort)
+				return true;
 	return false;
 }
 
-Server::Peer & Server::Priv::getPeer(const sockaddr_in & paddr)
+Server::Peer & Server::Priv::getPeer(const sockaddr_in6 & paddr)
 {
 	for (auto & peer : peers)
 		if (memcmp(&peer->addr, &paddr, sizeof paddr) == 0)
diff --git a/src/network.h b/src/network.h
index 4d232b3..a6ba3cd 100644
--- a/src/network.h
+++ b/src/network.h
@@ -43,7 +43,7 @@ struct Server::Peer
 	Peer & operator=(const Peer &) = delete;
 
 	Priv & server;
-	const sockaddr_in addr;
+	const sockaddr_in6 addr;
 
 	variant<monostate,
 		shared_ptr<struct WaitingRef>,
@@ -151,8 +151,8 @@ struct Server::Priv
 	void doListen();
 	void doAnnounce();
 
-	bool isSelfAddress(const sockaddr_in & paddr);
-	Peer & getPeer(const sockaddr_in & paddr);
+	bool isSelfAddress(const sockaddr_in6 & paddr);
+	Peer & getPeer(const sockaddr_in6 & paddr);
 	void handlePacket(Peer &, const TransportHeader &, ReplyBuilder &);
 
 	void handleLocalHeadChange(const Head<LocalState> &);
-- 
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