Add a module which implements the HAProxy PROXY v2 protocol.

1 files changed, 326 insertions, 0 deletions

diff --git a/src/modules/m_haproxy.cpp b/src/modules/m_haproxy.cpp
new file mode 100644
index 000000000..8272c2980
--- /dev/null
+++ b/src/modules/m_haproxy.cpp
@@ -0,0 +1,326 @@
+/*
+ * InspIRCd -- Internet Relay Chat Daemon
+ *
+ *   Copyright (C) 2018 Peter Powell <petpow@saberuk.com>
+ *
+ * This file is part of InspIRCd.  InspIRCd is free software: you can
+ * redistribute it and/or modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation, version 2.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+
+#include "inspircd.h"
+#include "iohook.h"
+
+enum
+{
+	// The family for TCP over IPv4.
+	PP2_FAMILY_IPV4 = 0x11,
+
+	// The length of the PP2_FAMILY_IPV4 endpoints.
+	PP2_FAMILY_IPV4_LENGTH = 12,
+
+	// The family for TCP over IPv6.
+	PP2_FAMILY_IPV6 = 0x21,
+
+	// The length of the PP2_FAMILY_IPV6 endpoints.
+	PP2_FAMILY_IPV6_LENGTH = 36,
+
+	// The family for UNIX sockets.
+	PP2_FAMILY_UNIX = 0x31,
+
+	// The length of the PP2_FAMILY_UNIX endpoints.
+	PP2_FAMILY_UNIX_LENGTH = 216,
+
+	// The bitmask we apply to extract the command.
+	PP2_COMMAND_MASK = 0x0F,
+
+	// The length of the PROXY protocol header.
+	PP2_HEADER_LENGTH = 16,
+
+	// The length of the PROXY protocol signature.
+	PP2_SIGNATURE_LENGTH = 12,
+
+	// The PROXY protocol version we support.
+	PP2_VERSION = 0x20,
+
+	// The bitmask we apply to extract the protocol version.
+	PP2_VERSION_MASK = 0xF0
+};
+
+enum HAProxyState
+{
+	// We are waiting for the PROXY header section.
+	HPS_WAITING_FOR_HEADER,
+
+	// We are waiting for the PROXY address section.
+	HPS_WAITING_FOR_ADDRESS,
+
+	// The client is fully connected.
+	HPS_CONNECTED
+};
+
+enum HAProxyCommand
+{
+	// LOCAL command.
+	HPC_LOCAL = 0x00,
+
+	// PROXY command.
+	HPC_PROXY = 0x01
+};
+
+struct HAProxyHeader
+{
+	// The signature used to identify the HAProxy protocol.
+	uint8_t signature[PP2_SIGNATURE_LENGTH];
+
+	// The version of the PROXY protocol and command being sent.
+	uint8_t version_command;
+
+	// The family for the address.
+	uint8_t family;
+
+	// The length of the address section.
+	uint16_t length;
+};
+
+class HAProxyHookProvider : public IOHookProvider
+{
+ public:
+	HAProxyHookProvider(Module* mod)
+		: IOHookProvider(mod, "haproxy", IOHookProvider::IOH_UNKNOWN, true)
+	{
+	}
+
+	void OnAccept(StreamSocket* sock, irc::sockets::sockaddrs* client, irc::sockets::sockaddrs* server) CXX11_OVERRIDE;
+
+	void OnConnect(StreamSocket* sock) CXX11_OVERRIDE
+	{
+		// We don't need to implement this.
+	}
+};
+
+// The signature for a HAProxy PROXY protocol header.
+static const char proxy_signature[13] = "\x0D\x0A\x0D\x0A\x00\x0D\x0A\x51\x55\x49\x54\x0A";
+
+class HAProxyHook : public IOHookMiddle
+{
+ private:
+	// The length of the address section.
+	uint16_t address_length;
+
+	// The endpoint the client is connecting from.
+	irc::sockets::sockaddrs client;
+
+	// The command sent by the proxy server.
+	HAProxyCommand command;
+
+	// The endpoint the client is connected to.
+	irc::sockets::sockaddrs server;
+
+	// The current state of the PROXY parser.
+	HAProxyState state;
+
+	int ReadProxyAddress(StreamSocket* sock)
+	{
+		// Block until we have the entire address.
+		std::string& recvq = GetRecvQ();
+		if (recvq.length() < address_length)
+			return 0;
+
+		switch (command)
+		{
+			case HPC_LOCAL:
+				// Skip the address completely.
+				recvq.erase(0, address_length);
+				break;
+
+			case HPC_PROXY:
+				// Store the endpoint information.
+				switch (client.family())
+				{
+					case AF_INET:
+						memcpy(&client.in4.sin_addr.s_addr, &recvq[0], 4);
+						memcpy(&server.in4.sin_addr.s_addr, &recvq[4], 8);
+						memcpy(&client.in4.sin_port, &recvq[8], 2);
+						memcpy(&server.in4.sin_port, &recvq[10], 2);
+						break;
+
+					case AF_INET6:
+						memcpy(client.in6.sin6_addr.s6_addr, &recvq[0], 16);
+						memcpy(server.in6.sin6_addr.s6_addr, &recvq[16], 16);
+						memcpy(&client.in6.sin6_port, &recvq[32], 2);
+						memcpy(&server.in6.sin6_port, &recvq[34], 2);
+						break;
+
+					case AF_UNIX:
+						memcpy(client.un.sun_path, &recvq[0], 108);
+						memcpy(client.un.sun_path, &recvq[108], 108);
+						break;
+				}
+
+				sock->OnSetEndPoint(server, client);
+
+				// XXX: HAProxy's PROXY v2 specification defines Type-Length-Values that
+				// could appear here but as of 2018-07-25 it does not send anything. We
+				// should revisit this in the future to see if they actually send them.
+				recvq.erase(0, address_length);
+		}
+
+		// We're done!
+		state = HPS_CONNECTED;
+		return 1;
+	}
+
+	int ReadProxyHeader(StreamSocket* sock)
+	{
+		// Block until we have a header.
+		std::string& recvq = GetRecvQ();
+		if (recvq.length() < PP2_HEADER_LENGTH)
+			return 0;
+
+		// Read the header.
+		HAProxyHeader header;
+		memcpy(&header, recvq.c_str(), PP2_HEADER_LENGTH);
+		recvq.erase(0, PP2_HEADER_LENGTH);
+
+		// Check we are actually parsing a HAProxy header.
+		if (memcmp(&header.signature, proxy_signature, PP2_SIGNATURE_LENGTH) != 0)
+		{
+			// If we've reached this point the proxy server did not send a proxy information.
+			sock->SetError("Invalid HAProxy PROXY signature");
+			return -1;
+		}
+
+		// We only support this version of the protocol.
+		const uint8_t version = (header.version_command & PP2_VERSION_MASK);
+		if (version != PP2_VERSION)
+		{
+			sock->SetError("Unsupported HAProxy PROXY protocol version");
+			return -1;
+		}
+
+		// We only support the LOCAL and PROXY commands.
+		command = static_cast<HAProxyCommand>(header.version_command & PP2_COMMAND_MASK);
+		switch (command)
+		{
+			case HPC_LOCAL:
+				// Intentionally left blank.
+				break;
+
+			case HPC_PROXY:
+				// Check the protocol support and initialise the sockaddrs.
+				uint16_t shortest_length;
+				switch (header.family)
+				{
+					case PP2_FAMILY_IPV4: // TCP over IPv4.
+						client.sa.sa_family = server.sa.sa_family = AF_INET;
+						shortest_length = PP2_FAMILY_IPV4_LENGTH;
+						break;
+
+					case PP2_FAMILY_IPV6: // TCP over IPv6.
+						client.sa.sa_family = server.sa.sa_family = AF_INET6;
+						shortest_length = PP2_FAMILY_IPV6_LENGTH;
+						break;
+
+					case PP2_FAMILY_UNIX: // UNIX stream.
+						client.sa.sa_family = server.sa.sa_family = AF_UNIX;
+						shortest_length = PP2_FAMILY_UNIX_LENGTH;
+						break;
+
+					default: // Unknown protocol.
+						sock->SetError("Invalid HAProxy PROXY protocol type");
+						return -1;
+				}
+
+				// Check that the length can actually contain the addresses.
+				address_length = ntohs(header.length);
+				if (address_length < shortest_length)
+				{
+					sock->SetError("Truncated HAProxy PROXY address section");
+					return -1;
+				}
+				break;
+
+			default:
+				sock->SetError("Unsupported HAProxy PROXY command");
+				return -1;
+		}
+
+		state = HPS_WAITING_FOR_ADDRESS;
+		return ReadProxyAddress(sock);
+	}
+
+ public:
+	HAProxyHook(IOHookProvider* Prov, StreamSocket* sock)
+		: IOHookMiddle(Prov)
+		, state(HPS_WAITING_FOR_HEADER)
+	{
+		sock->AddIOHook(this);
+	}
+
+	int OnStreamSocketWrite(StreamSocket* sock, StreamSocket::SendQueue& uppersendq) CXX11_OVERRIDE
+	{
+		// We don't need to implement this.
+		GetSendQ().moveall(uppersendq);
+		return 1;
+	}
+
+	int OnStreamSocketRead(StreamSocket* sock, std::string& destrecvq) CXX11_OVERRIDE
+	{
+		switch (state)
+		{
+			case HPS_WAITING_FOR_HEADER:
+				return ReadProxyHeader(sock);
+
+			case HPS_WAITING_FOR_ADDRESS:
+				return ReadProxyAddress(sock);
+
+			case HPS_CONNECTED:
+				std::string& recvq = GetRecvQ();
+				destrecvq.append(recvq);
+				recvq.clear();
+				return 1;
+		}
+
+		// We should never reach this point.
+		return -1;
+	}
+
+	void OnStreamSocketClose(StreamSocket* sock) CXX11_OVERRIDE
+	{
+		// We don't need to implement this.
+	}
+};
+
+void HAProxyHookProvider::OnAccept(StreamSocket* sock, irc::sockets::sockaddrs* client, irc::sockets::sockaddrs* server)
+{
+	new HAProxyHook(this, sock);
+}
+
+class ModuleHAProxy : public Module
+{
+ private:
+	reference<HAProxyHookProvider> hookprov;
+
+ public:
+	ModuleHAProxy()
+		: hookprov(new HAProxyHookProvider(this))
+	{
+	}
+
+	Version GetVersion() CXX11_OVERRIDE
+	{
+		return Version("Provides support for the HAProxy PROXY protocol", VF_VENDOR);
+	}
+};
+
+MODULE_INIT(ModuleHAProxy)