From a63fcfa5b419307176eb11173c0202c8ba34d181 Mon Sep 17 00:00:00 2001
From: Jason Volk <jason@zemos.net>
Date: Thu, 24 Dec 2020 17:40:31 -0800
Subject: [PATCH] ircd::net: Add interface to TCP_QUICKACK if supported.

---
 include/ircd/net/sock_opts.h |  3 +++
 ircd/net.cc                  | 48 ++++++++++++++++++++++++++++++++++++
 2 files changed, 51 insertions(+)

diff --git a/include/ircd/net/sock_opts.h b/include/ircd/net/sock_opts.h
index 269ba4c70..4998d9773 100644
--- a/include/ircd/net/sock_opts.h
+++ b/include/ircd/net/sock_opts.h
@@ -18,6 +18,7 @@ namespace ircd::net
 	bool v6only(const socket &);
 	bool blocking(const socket &);
 	bool nodelay(const socket &);
+	bool quickack(const socket &);
 	bool keepalive(const socket &);
 	time_t linger(const socket &);
 	size_t read_bufsz(const socket &);
@@ -28,6 +29,7 @@ namespace ircd::net
 	void v6only(socket &, const bool &);
 	void blocking(socket &, const bool &);
 	void nodelay(socket &, const bool &);
+	void quickack(socket &, const bool &);
 	void keepalive(socket &, const bool &);
 	void linger(socket &, const time_t &); // -1 is OFF; >= 0 is ON
 	void read_bufsz(socket &, const size_t &bytes);
@@ -50,6 +52,7 @@ struct ircd::net::sock_opts
 	int8_t v6only { IGN };
 	int8_t blocking { IGN };             // Simulates blocking behavior
 	int8_t nodelay { IGN };
+	int8_t quickack { IGN };
 	int8_t keepalive { IGN };
 	time_t linger { IGN };               // -1 is OFF; >= 0 is ON
 	ssize_t read_bufsz { IGN };
diff --git a/ircd/net.cc b/ircd/net.cc
index fddb2d84c..9e7b31353 100644
--- a/ircd/net.cc
+++ b/ircd/net.cc
@@ -795,6 +795,7 @@ ircd::net::sock_opts::sock_opts(const socket &socket)
 :v6only{net::v6only(socket)}
 ,blocking{net::blocking(socket)}
 ,nodelay{net::nodelay(socket)}
+,quickack{net::quickack(socket)}
 ,keepalive{net::keepalive(socket)}
 ,linger{net::linger(socket)}
 ,read_bufsz{ssize_t(net::read_bufsz(socket))}
@@ -819,6 +820,9 @@ ircd::net::set(socket &socket,
 	if(opts.nodelay != opts.IGN)
 		net::nodelay(socket, opts.nodelay);
 
+	if(opts.quickack != opts.IGN)
+		net::quickack(socket, opts.quickack);
+
 	if(opts.keepalive != opts.IGN)
 		net::keepalive(socket, opts.keepalive);
 
@@ -919,6 +923,27 @@ ircd::net::keepalive(socket &socket,
 	sd.set_option(option);
 }
 
+void
+ircd::net::quickack(socket &socket,
+                    const bool &b)
+#if defined(TCP_QUICKACK) && defined(SOL_SOCKET)
+{
+	ip::tcp::socket &sd(socket);
+	const auto &fd
+	{
+		sd.lowest_layer().native_handle()
+	};
+
+	const int val(b);
+	const socklen_t len(sizeof(val));
+	syscall(::setsockopt, fd, SOL_SOCKET, TCP_QUICKACK, &val, len);
+}
+#else
+{
+	#warning "TCP_QUICKACK is not defined on this platform."
+}
+#endif
+
 void
 ircd::net::nodelay(socket &socket,
                    const bool &b)
@@ -1023,6 +1048,29 @@ ircd::net::keepalive(const socket &socket)
 	return option.value();
 }
 
+bool
+ircd::net::quickack(const socket &socket)
+#if defined(TCP_QUICKACK) && defined(SOL_SOCKET)
+{
+	const ip::tcp::socket &sd(socket);
+	const auto &fd
+	{
+		mutable_cast(sd).lowest_layer().native_handle()
+	};
+
+	uint32_t ret;
+	socklen_t len(sizeof(ret));
+	syscall(::getsockopt, fd, SOL_SOCKET, TCP_QUICKACK, &ret, &len);
+	assert(len <= sizeof(ret));
+	return ret;
+}
+#else
+{
+	#warning "TCP_QUICKACK is not defined on this platform."
+	return false;
+}
+#endif
+
 bool
 ircd::net::nodelay(const socket &socket)
 {