add setKeepAliveParams method

source/eventcore/driver.d

@@ -215,6 +215,19 @@ interface EventDriverSockets {
 	/// Sets to `SO_KEEPALIVE` socket option on a socket.
 	void setKeepAlive(StreamSocketFD socket, bool enable);
 
+	/** Enables keepalive for the TCP socket and sets additional parameters.
+		Silently ignores unsupported systems.
+
+		Params:
+			socket = Socket file descriptor to set options on.
+			idle = The time the connection needs to remain idle
+				before TCP starts sending keepalive probes.
+			interval = The time between individual keepalive probes.
+			probeCount = The maximum number of keepalive probes TCP should send
+				before dropping the connection. Has no effect on Windows.
+	*/
+	void setKeepAliveParams(StreamSocketFD socket, Duration idle, Duration interval, int probeCount = 5);
+
 	/** Reads data from a stream socket.
 
 		Note that only a single read operation is allowed at once. The caller

source/eventcore/drivers/posix/sockets.d

@@ -8,6 +8,8 @@ import eventcore.internal.utils;
 import std.algorithm.comparison : among, min, max;
 import std.socket : Address, AddressFamily, InternetAddress, Internet6Address, UnknownAddress;
 
+import core.time: Duration;
+
 version (Posix) {
 	import std.socket : UnixAddress;
 	import core.sys.posix.netdb : AI_ADDRCONFIG, AI_V4MAPPED, addrinfo, freeaddrinfo, getaddrinfo;
@@ -45,6 +47,13 @@ version (linux) {
 	}
 	else
 		import core.sys.linux.netinet.in_ : IP_ADD_MEMBERSHIP, IP_MULTICAST_LOOP;
+
+	// Linux-specific TCP options
+	// https://github.com/torvalds/linux/blob/master/include/uapi/linux/tcp.h#L95
+	enum SOL_TCP = 6;
+	enum TCP_KEEPIDLE = 4;
+	enum TCP_KEEPINTVL = 5;
+	enum TCP_KEEPCNT = 6;
 }
 version(OSX) {
 	static if (__VERSION__ < 2077) {
@@ -300,6 +309,19 @@ final class PosixEventDriverSockets(Loop : PosixEventLoop) : EventDriverSockets
 		() @trusted { setsockopt(cast(sock_t)socket, SOL_SOCKET, SO_KEEPALIVE, cast(char*)&opt, opt.sizeof); } ();
 	}
 
+	override void setKeepAliveParams(StreamSocketFD socket, Duration idle, Duration interval, int probeCount) @trusted
+	{
+		version (linux) {
+			ubyte opt = 1;
+			setsockopt(cast(sock_t)socket, SOL_SOCKET, SO_KEEPALIVE, cast(char*)&opt, opt.sizeof);
+			int int_opt = cast(int) idle.total!"seconds"();
+			setsockopt(cast(sock_t)socket, SOL_TCP, TCP_KEEPIDLE, &int_opt, int.sizeof);
+			int_opt = cast(int) interval.total!"seconds"();
+			setsockopt(cast(sock_t)socket, SOL_TCP, TCP_KEEPINTVL, &int_opt, int.sizeof);
+			setsockopt(cast(sock_t)socket, SOL_TCP, TCP_KEEPCNT, &probeCount, int.sizeof);
+		}
+	}
+
 	final override void read(StreamSocketFD socket, ubyte[] buffer, IOMode mode, IOCallback on_read_finish)
 	{
 		/*if (buffer.length == 0) {

source/eventcore/drivers/winapi/sockets.d

@@ -221,6 +221,18 @@ final class WinAPIEventDriverSockets : EventDriverSockets {
 		setsockopt(socket, SOL_SOCKET, SO_KEEPALIVE, &eni, eni.sizeof);
 	}
 
+	override void setKeepAliveParams(StreamSocketFD socket, Duration idle, Duration interval, int probeCount) @trusted
+	{
+		if (idle < Duration.zero)
+			assert(0, "negative idle duration");
+		if (interval < Duration.zero)
+			assert(0, "negative interval duration");
+		tcp_keepalive opts = tcp_keepalive(1, cast(ulong) idle.total!"msecs"(),
+			cast(ulong) interval.total!"msecs");
+		int result = WSAIoctl(socket, SIO_KEEPALIVE_VALS, &opts, tcp_keepalive.sizeof, null, 0, null, null);
+		assert(result == 0);
+	}
+
 	override void read(StreamSocketFD socket, ubyte[] buffer, IOMode mode, IOCallback on_read_finish)
 	{
 		auto slot = () @trusted { return &m_sockets[socket].streamSocket(); } ();

source/eventcore/internal/win32.d

@@ -104,6 +104,29 @@ struct ADDRINFOW {
 	ADDRINFOW* ai_next;
 }
 
+// https://msdn.microsoft.com/en-us/library/windows/desktop/dd877220(v=vs.85).aspx
+struct tcp_keepalive {
+	ulong onoff;
+	ulong keepalivetime;
+	ulong keepaliveinterval;
+};
+
+// https://gist.github.com/piscisaureus/906386#file-winsock2-h-L1099
+enum : ulong {
+	IOC_VENDOR = 0x18000000,
+	IOC_OUT = 0x40000000,
+	IOC_IN = 0x80000000
+}
+
+ulong _WSAIOW(ulong x, ulong y) pure @safe
+{
+	return IOC_IN | x | y;
+}
+
+enum : ulong {
+	SIO_KEEPALIVE_VALS = _WSAIOW(IOC_VENDOR, 4)
+}
+
 struct WSAPROTOCOL_INFO {
 	DWORD            dwServiceFlags1;
 	DWORD            dwServiceFlags2;
@@ -154,6 +177,7 @@ void FreeAddrInfoExW(ADDRINFOEXW* pAddrInfo);
 void freeaddrinfo(ADDRINFOA* ai);
 BOOL TransmitFile(SOCKET hSocket, HANDLE hFile, DWORD nNumberOfBytesToWrite, DWORD nNumberOfBytesPerSend, OVERLAPPED* lpOverlapped, LPTRANSMIT_FILE_BUFFERS lpTransmitBuffers, DWORD dwFlags);
 BOOL CancelIoEx(HANDLE hFile, LPOVERLAPPED lpOverlapped);
+int WSAIoctl(SOCKET s, DWORD dwIoControlCode, void* lpvInBuffer, DWORD cbInBuffer, void* lpvOutBuffer, DWORD cbOutBuffer, DWORD* lpcbBytesReturned, in WSAOVERLAPPEDX* lpOverlapped, LPWSAOVERLAPPED_COMPLETION_ROUTINEX lpCompletionRoutine);
 
 /*struct WSAOVERLAPPEDX {
 	ULONG_PTR Internal;