From c39af624aa1c9f70dac1a9d35bbc054524d09fa6 Mon Sep 17 00:00:00 2001
From: no92 <leo@managarm.org>
Date: Mon, 8 Jul 2024 13:54:31 +0200
Subject: [PATCH] netserver: implement TCP socket support for SO_BINDTODEVICE

---
 servers/netserver/src/ip/ip4.cpp  | 13 ++++++++----
 servers/netserver/src/ip/ip4.hpp  |  5 +++--
 servers/netserver/src/ip/tcp4.cpp | 35 ++++++++++++++++++++++++++++++-
 3 files changed, 46 insertions(+), 7 deletions(-)

diff --git a/servers/netserver/src/ip/ip4.cpp b/servers/netserver/src/ip/ip4.cpp
index fda735d63..36e30a40b 100644
--- a/servers/netserver/src/ip/ip4.cpp
+++ b/servers/netserver/src/ip/ip4.cpp
@@ -30,10 +30,13 @@ bool Ip4Router::addRoute(Route r) {
 	return routes.emplace(std::move(r)).second;
 }
 
-std::optional<Route> Ip4Router::resolveRoute(uint32_t ip) {
+std::optional<Route> Ip4Router::resolveRoute(uint32_t ip, std::shared_ptr<nic::Link> link) {
 	for (auto i = routes.begin(); i != routes.end(); i++) {
 		const auto &r = *i;
 		if (r.network.sameNet(ip)) {
+			if(link && r.link.lock()->index() != link->index())
+				continue;
+
 			if (r.link.expired()) {
 				i = routes.erase(i);
 				continue;
@@ -230,8 +233,8 @@ async::result<frg::expected<protocols::fs::Error, size_t>> Ip4Socket::sendmsg(vo
 }
 
 async::result<std::optional<Ip4TargetInfo>>
-Ip4::targetByRemote(uint32_t remote) {
-	auto oroute = ip4Router().resolveRoute(remote);
+Ip4::targetByRemote(uint32_t remote, std::shared_ptr<nic::Link> link) {
+	auto oroute = ip4Router().resolveRoute(remote, link);
 	if (!oroute) {
 		std::cout << "netserver: net unreachable" << std::endl;
 		co_return std::nullopt;
@@ -329,7 +332,9 @@ async::result<protocols::fs::Error> Ip4::sendFrame(Ip4TargetInfo ti,
 
 void Ip4::feedPacket(nic::MacAddress, nic::MacAddress,
 		arch::dma_buffer owner, arch::dma_buffer_view frame, std::weak_ptr<nic::Link> link) {
-	Ip4Packet hdr;
+	Ip4Packet hdr{};
+	hdr.link = link;
+
 	if (!hdr.parse(std::move(owner), frame)) {
 		std::cout << "netserver: runt, or otherwise invalid, ip4 frame received"
 			<< std::endl;
diff --git a/servers/netserver/src/ip/ip4.hpp b/servers/netserver/src/ip/ip4.hpp
index 8ce49caf2..016b31ad0 100644
--- a/servers/netserver/src/ip/ip4.hpp
+++ b/servers/netserver/src/ip/ip4.hpp
@@ -63,7 +63,7 @@ struct Ip4Router {
 
 	// false if insertion fails
 	bool addRoute(Route r);
-	std::optional<Route> resolveRoute(uint32_t ip);
+	std::optional<Route> resolveRoute(uint32_t ip, std::shared_ptr<nic::Link> link = {});
 
 	inline const std::set<Route> &getRoutes() const {
 		return routes;
@@ -106,6 +106,7 @@ class Ip4Packet {
 	} header;
 	static_assert(sizeof(header) == 20, "bad header size");
 	arch::dma_buffer_view data;
+	std::weak_ptr<nic::Link> link;
 
 	inline arch::dma_buffer_view payload() const {
 		return data.subview(header.ihl * 4);
@@ -140,7 +141,7 @@ struct Ip4 {
 	void setLink(CidrAddress addr, std::weak_ptr<nic::Link> link);
 	std::optional<uint32_t> findLinkIp(uint32_t ipOnNet, nic::Link *link);
 
-	async::result<std::optional<Ip4TargetInfo>> targetByRemote(uint32_t);
+	async::result<std::optional<Ip4TargetInfo>> targetByRemote(uint32_t, std::shared_ptr<nic::Link> link = {});
 	async::result<protocols::fs::Error> sendFrame(Ip4TargetInfo,
 		void*, size_t,
 		uint16_t);
diff --git a/servers/netserver/src/ip/tcp4.cpp b/servers/netserver/src/ip/tcp4.cpp
index ba24f48ae..dffeba79c 100644
--- a/servers/netserver/src/ip/tcp4.cpp
+++ b/servers/netserver/src/ip/tcp4.cpp
@@ -5,6 +5,7 @@
 #include <arch/variable.hpp>
 #include <protocols/fs/server.hpp>
 #include <cstring>
+#include <format>
 #include <iomanip>
 #include <random>
 #include <fcntl.h>
@@ -493,6 +494,32 @@ struct Tcp4Socket {
 		co_return 0;
 	}
 
+	static async::result<frg::expected<protocols::fs::Error>> setSocketOption(void *object,
+		int layer, int number, std::vector<char> optbuf) {
+		auto self = static_cast<Tcp4Socket *>(object);
+
+		if(layer == SOL_SOCKET && number == SO_BINDTODEVICE) {
+			std::string ifname{optbuf.data()};
+
+			if(ifname.empty()) {
+				self->boundInterface_ = {};
+			} else {
+				auto nic = nic::Link::byName(ifname);
+
+				if(!nic)
+					co_return protocols::fs::Error::illegalArguments;
+
+				self->boundInterface_ = nic;
+				co_return {};
+			}
+		}
+
+		std::cout << std::format("netserver: unhandled TCP socket setsockopt layer {} number {}\n",
+			layer, number);
+
+		co_return protocols::fs::Error::invalidProtocolOption;
+	}
+
 	constexpr static protocols::fs::FileOperations ops {
 		.read = &read,
 		.write = &write,
@@ -507,6 +534,7 @@ struct Tcp4Socket {
 		.recvMsg = &recvMsg,
 		.sendMsg = &sendMsg,
 		.peername = &peername,
+		.setSocketOption = &setSocketOption,
 	};
 
 	bool bindAvailable(uint32_t ipAddress = INADDR_ANY) {
@@ -575,6 +603,8 @@ struct Tcp4Socket {
 	uint64_t outSeq_ = 0;
 	uint64_t hupSeq_ = 1;
 	async::recurring_event pollEvent_;
+
+	std::shared_ptr<nic::Link> boundInterface_ = {};
 };
 
 async::result<void> Tcp4Socket::flushOutPackets_() {
@@ -596,7 +626,7 @@ async::result<void> Tcp4Socket::flushOutPackets_() {
 			localFlushedSn_ = randomSn;
 
 			// Construct and transmit the initial SYN packet.
-			auto targetInfo = co_await ip4().targetByRemote(remoteEp_.ipAddress);
+			auto targetInfo = co_await ip4().targetByRemote(remoteEp_.ipAddress, boundInterface_);
 			if (!targetInfo) {
 				// TODO: Return an error to users.
 				std::cout << "netserver: Destination unreachable" << std::endl;
@@ -722,6 +752,9 @@ async::result<void> Tcp4Socket::flushOutPackets_() {
 }
 
 void Tcp4Socket::handleInPacket_(TcpPacket packet) {
+	if(boundInterface_ && boundInterface_->index() != packet.packet->link.lock()->index())
+		return;
+
 	if(connectState_ == ConnectState::sendSyn) {
 		if(localSettledSn_ == localFlushedSn_) {
 			std::cout << "netserver: Rejecting packet before SYN is sent [sendSyn]"