--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/Socket.cpp	Sun Aug 21 00:16:50 2022 +0200
@@ -0,0 +1,412 @@
+/**
+ * Relational pipes
+ * Copyright © 2022 František Kučera (Frantovo.cz, GlobalCode.info)
+ *
+ * This program 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 3 of the License.
+ *
+ * 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 <string>
+#include <cstring>
+#include <unistd.h>
+#include <stdexcept>
+#include <arpa/inet.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <netinet/in.h>
+#include <vector>
+#include <memory>
+#include <regex>
+#include <iostream>
+#include <netdb.h>
+
+#include "Socket.h"
+
+namespace relpipe {
+namespace in {
+namespace socket {
+
+using namespace relpipe::in::socket::options;
+
+static const std::string findOption(SocketOptions options, std::string name, bool required = false, const std::string defaultValue = "") {
+	for (auto o : options) if (o.name == name) return o.value;
+	if (required) throw std::invalid_argument("Option " + name + " is required but was not found");
+	else return defaultValue;
+}
+
+class FD {
+private:
+	int fd;
+public:
+
+	FD(int fd) : fd(fd) {
+	};
+
+	virtual ~FD() {
+		close(fd);
+	}
+
+	int getFD() {
+		return fd;
+	}
+};
+
+static void check(int result, std::string message) {
+	if (result == 0); // OK
+	else throw std::logic_error("Got error result: " + message + ": " + strerror(errno) + " (result=" + std::to_string(result) + ", errno=" + std::to_string(errno) + ")");
+}
+
+class AddressInfos {
+private:
+	std::shared_ptr<addrinfo> addrInfo;
+
+	AddressInfos(addrinfo* addrInfo) : addrInfo(std::shared_ptr<addrinfo>(addrInfo, freeaddrinfo)) {
+	}
+
+public:
+
+	virtual ~AddressInfos() {
+	}
+
+	class AddressInfo {
+	private:
+		std::shared_ptr<addrinfo> parent; // to avoid premature deletion of the whole structure
+	public:
+		const addrinfo * const ai;
+
+		AddressInfo(const addrinfo * const ai, std::shared_ptr<addrinfo> parent) : ai(ai), parent(parent) {
+		}
+
+		const std::string toString() const {
+			char buffer[INET6_ADDRSTRLEN] = {0};
+			if (ai->ai_family == AF_INET) return inet_ntop(ai->ai_family, &((sockaddr_in const *) ai->ai_addr)->sin_addr, buffer, sizeof (buffer)); // TODO: check 0 result
+			else if (ai->ai_family == AF_INET6) return inet_ntop(ai->ai_family, &((sockaddr_in6 const *) ai->ai_addr)->sin6_addr, buffer, sizeof (buffer)); // TODO: check 0 result
+			else return "unknown address family: " + std::to_string(ai->ai_family);
+		}
+	};
+
+	static AddressInfos getAddressInfos(const std::string& host, const std::string& port, int socketType = SOCK_STREAM, int protocol = IPPROTO_TCP) {
+		struct addrinfo query;
+		memset(&query, sizeof (query), 0);
+		query.ai_family = AF_UNSPEC;
+		query.ai_socktype = socketType;
+		query.ai_protocol = protocol;
+		query.ai_flags = AI_ALL;
+
+		struct addrinfo* addrInfo;
+		check(getaddrinfo(host.c_str(), port.c_str(), &query, &addrInfo), "getaddrinfo");
+
+		return AddressInfos(addrInfo);
+	}
+
+	const std::size_t size() const {
+		std::size_t size = 0;
+		for (addrinfo* ai = addrInfo.get(); ai; ai = ai->ai_next) size++;
+		return size;
+	}
+
+	const AddressInfo operator[](std::size_t index) const {
+		for (addrinfo* ai = addrInfo.get(); ai; index--) {
+			if (index == 0) return AddressInfo(ai, addrInfo);
+			else ai = ai->ai_next;
+		}
+
+		throw std::out_of_range("invalid index for AddressInfo: " + std::to_string(index));
+	}
+
+};
+
+template<class SocketClass, class... MoreArgs> static std::shared_ptr<SocketClass> openClientSocket(const SocketOptions& options, int socketType, int protocol, MoreArgs... moreArgs) {
+	AddressInfos remoteAddresses = AddressInfos::getAddressInfos(
+			findOption(options, OPTION_HOST, true),
+			findOption(options, OPTION_PORT, true),
+			socketType,
+			protocol);
+
+	return std::shared_ptr<SocketClass>(new SocketClass(remoteAddresses[0], moreArgs...));
+}
+
+/**
+ * abstract class for sockets that use sendmsg() / recvmsg()
+ */
+class MSGSocket : public Socket {
+protected:
+	FD socket;
+
+	void sendmsg(const std::string& message) {
+		iovec iov[1];
+		msghdr msg = {};
+		msg.msg_iov = iov;
+		msg.msg_iov[0].iov_base = (void*) message.c_str();
+		msg.msg_iov[0].iov_len = message.size();
+		msg.msg_iovlen = sizeof (iov) / sizeof (iov[0]);
+		ssize_t written = ::sendmsg(socket.getFD(), &msg, 0);
+		if (written != message.size()) throw std::logic_error("writing to the socket failed");
+	}
+public:
+
+	MSGSocket(int socket) : socket(socket) {
+	}
+
+	void send(const OutgoingMessage& message) {
+		sendmsg(message.data);
+	}
+
+};
+
+class UDPClientSocket : public Socket {
+private:
+	AddressInfos::AddressInfo remoteAddress;
+	useconds_t delay = 0;
+	FD socket;
+
+public:
+
+	UDPClientSocket(AddressInfos::AddressInfo remoteAddress) : remoteAddress(remoteAddress), socket(::socket(remoteAddress.ai->ai_family, remoteAddress.ai->ai_socktype, remoteAddress.ai->ai_protocol)) {
+	}
+
+	static std::shared_ptr<Socket> open(const SocketOptions& options) {
+		auto socket = openClientSocket<UDPClientSocket>(options, SOCK_DGRAM, IPPROTO_UDP);
+		socket->delay = std::stol(findOption(options, OPTION_DELAY, false, "0")); // TODO: Move to SocketHandler? Or delete.
+		return socket;
+	}
+
+	void send(const OutgoingMessage& message) override {
+		auto ai = remoteAddress.ai;
+		sendto(socket.getFD(), message.data.c_str(), message.data.size(), 0, ai->ai_addr, ai->ai_addrlen);
+		if (delay) usleep(delay);
+	}
+
+	const IncomingMessage receive() override {
+		// TODO: UDP receive()
+		return IncomingMessage("TODO: receive() a message");
+	}
+};
+
+class UDPServerSocket : public Socket {
+private:
+	AddressInfos::AddressInfo localAddress;
+	sockaddr_in6 remoteAddressForSending = {};
+	useconds_t delay = 0;
+	FD socket;
+
+public:
+
+	UDPServerSocket(AddressInfos::AddressInfo remoteAddress) : localAddress(remoteAddress), socket(::socket(remoteAddress.ai->ai_family, remoteAddress.ai->ai_socktype, remoteAddress.ai->ai_protocol)) {
+	}
+
+	static std::shared_ptr<Socket> open(const SocketOptions& options) {
+		auto socket = openClientSocket<UDPServerSocket>(options, SOCK_DGRAM, IPPROTO_UDP);
+		auto ai = socket->localAddress.ai;
+		int reuseAddr = true;
+		check(::setsockopt(socket->socket.getFD(), SOL_SOCKET, SO_REUSEADDR, &reuseAddr, sizeof (reuseAddr)), "setsockopt SO_REUSEADDR");
+		check(::bind(socket->socket.getFD(), ai->ai_addr, ai->ai_addrlen), "bind");
+		return socket;
+	}
+
+	void send(const OutgoingMessage& message) override {
+		// receive a message first to get a remote address:
+		char buffer[8192];
+		memset((char *) &remoteAddressForSending, 0, sizeof (remoteAddressForSending));
+		socklen_t remoteAddressSize = sizeof (remoteAddressForSending);
+		ssize_t msgSize = recvfrom(socket.getFD(), buffer, sizeof (buffer), 0, (sockaddr*) & remoteAddressForSending, &remoteAddressSize);
+
+		// respond with our messsage:
+		sendto(socket.getFD(), message.data.c_str(), message.data.size(), 0, (sockaddr*) & remoteAddressForSending, remoteAddressSize);
+	}
+
+	const IncomingMessage receive() override {
+		char buffer[8192];
+		sockaddr_in6 remoteAddress;
+		memset((char *) &remoteAddress, 0, sizeof (remoteAddress));
+		socklen_t remoteAddressSize = sizeof (remoteAddress);
+		ssize_t msgSize = recvfrom(socket.getFD(), buffer, sizeof (buffer), 0, (sockaddr*) & remoteAddress, &remoteAddressSize);
+		check(msgSize < 0, "recvfrom");
+
+		IncomingMessage message(std::string(buffer, std::min(sizeof (buffer), (size_t) msgSize)));
+
+		// TODO: move to a common method
+		char hostBuffer[INET6_ADDRSTRLEN] = {0};
+		if (remoteAddress.sin6_family == AF_INET) {
+			sockaddr_in* remoteAddress4 = (sockaddr_in*) & remoteAddress;
+			message.remoteHost = inet_ntop(remoteAddress4->sin_family, &remoteAddress4->sin_addr, hostBuffer, sizeof (hostBuffer)); // TODO: check 0 result
+			message.remotePort = remoteAddress4->sin_port;
+		} else if (remoteAddress.sin6_family == AF_INET6) {
+			message.remoteHost = inet_ntop(remoteAddress.sin6_family, &remoteAddress.sin6_addr, hostBuffer, sizeof (hostBuffer)); // TODO: check 0 result
+			message.remotePort = remoteAddress.sin6_port;
+		}
+
+		return message;
+	}
+};
+
+class TCPClientSocket : public Socket {
+private:
+	AddressInfos::AddressInfo remoteAddress;
+
+public:
+
+	TCPClientSocket(AddressInfos::AddressInfo remoteAddress) : remoteAddress(remoteAddress) {
+	}
+
+	static std::shared_ptr<Socket> open(const SocketOptions& options) {
+		return openClientSocket<TCPClientSocket>(options, SOCK_STREAM, IPPROTO_TCP);
+	}
+
+	void send(const OutgoingMessage& message) override {
+		auto ai = remoteAddress.ai;
+		FD s(::socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol));
+		check(::connect(s.getFD(), ai->ai_addr, ai->ai_addrlen), "connect socket");
+		ssize_t written = ::write(s.getFD(), message.data.c_str(), message.data.size());
+		if (written != message.data.size()) throw std::logic_error("writing to the socket failed");
+		// TODO: partial writes, repeat
+	}
+
+	const IncomingMessage receive() override {
+		// TODO: TCP receive()
+		return IncomingMessage("TODO: receive() a message");
+	}
+};
+
+class TCPServerSocket : public Socket {
+private:
+	AddressInfos::AddressInfo localAddress;
+	FD socket;
+public:
+
+	TCPServerSocket(AddressInfos::AddressInfo localAddress) : localAddress(localAddress), socket(::socket(localAddress.ai->ai_family, localAddress.ai->ai_socktype, localAddress.ai->ai_protocol)) {
+	}
+
+	static std::shared_ptr<Socket> open(const SocketOptions& options) {
+		auto socket = openClientSocket<TCPServerSocket>(options, SOCK_STREAM, IPPROTO_TCP);
+		auto ai = socket->localAddress.ai;
+		int reuseAddr = true;
+		check(::setsockopt(socket->socket.getFD(), SOL_SOCKET, SO_REUSEADDR, &reuseAddr, sizeof (reuseAddr)), "setsockopt SO_REUSEADDR");
+		check(::bind(socket->socket.getFD(), ai->ai_addr, ai->ai_addrlen), "bind");
+		check(::listen(socket->socket.getFD(), 10), "listen"); // TODO: configurable backlog connection count?
+		return socket;
+	}
+
+	void send(const OutgoingMessage& message) override {
+		FD clientSocket(accept(socket.getFD(), nullptr, 0));
+		ssize_t written = ::write(clientSocket.getFD(), message.data.c_str(), message.data.size());
+		if (written != message.data.size()) throw std::logic_error("writing to the socket failed");
+		// TODO: partial writes, repeat
+	}
+
+	const IncomingMessage receive() override {
+		// TODO: TCP receive()
+		return IncomingMessage("TODO: receive() a message");
+	}
+};
+
+class SCTPClientSocket : public MSGSocket {
+private:
+	AddressInfos::AddressInfo remoteAddress;
+public:
+
+	SCTPClientSocket(AddressInfos::AddressInfo remoteAddress) : remoteAddress(remoteAddress), MSGSocket(::socket(remoteAddress.ai->ai_family, remoteAddress.ai->ai_socktype, remoteAddress.ai->ai_protocol)) {
+	}
+
+	static std::shared_ptr<Socket> open(const SocketOptions& options) {
+		auto socket = openClientSocket<SCTPClientSocket>(options, SOCK_STREAM, IPPROTO_SCTP);
+		check(::connect(socket->socket.getFD(), socket->remoteAddress.ai->ai_addr, socket->remoteAddress.ai->ai_addrlen), "connect socket");
+		return socket;
+	}
+
+	const IncomingMessage receive() override {
+		// TODO: SCTP receive()
+		return IncomingMessage("TODO: receive() a message");
+	}
+};
+
+class UDSClientSocket : public MSGSocket {
+public:
+
+	UDSClientSocket(int fd) : MSGSocket(fd) {
+	}
+
+	static std::shared_ptr<Socket> open(const SocketOptions& options) {
+		struct sockaddr_un address;
+		std::string path = findOption(options, OPTION_PATH);
+
+		memset(&address, 0x00, sizeof (address));
+		address.sun_family = AF_UNIX;
+		strncpy(address.sun_path, path.c_str(), path.size());
+
+		int fd = ::socket(AF_UNIX, SOCK_STREAM, 0);
+
+		auto socket = std::make_shared<UDSClientSocket>(fd);
+		check(::connect(socket->socket.getFD(), (const sockaddr*) &address, sizeof (address)), "connect socket");
+
+
+		if (findOption(options, "debug") == "true") { // TODO: undocumented feature → standardize or remove
+			struct ucred credentials;
+			socklen_t credentialsLength = sizeof (credentials);
+			memset(&credentials, 0x00, credentialsLength);
+			getsockopt(fd, SOL_SOCKET, SO_PEERCRED, &credentials, &credentialsLength);
+
+			printf("uds.fd = %d\n", fd);
+			printf("uds.path = %s\n", address.sun_path);
+			printf("uds.server.pid = %d\n", credentials.pid);
+			printf("uds.server.uid = %d\n", credentials.uid);
+			printf("uds.server.gid = %d\n", credentials.gid);
+		}
+
+
+		return socket;
+	}
+
+	const IncomingMessage receive() override {
+		// TODO: UDS receive()
+		return IncomingMessage("TODO: receive() a message");
+	}
+};
+
+template<const char* protocol, const char* role, const char* mode, typename SocketClass>
+class TemplateSocketFactory : public SocketFactory {
+public:
+
+	bool canHandle(const SocketOptions& options) override {
+		return findOption(options, OPTION_PROTOCOL) == protocol
+				&& findOption(options, OPTION_ROLE) == role
+				&& findOption(options, OPTION_MODE) == mode;
+	}
+
+	std::shared_ptr<Socket> open(const SocketOptions& options) override {
+		return SocketClass::open(options);
+	}
+};
+
+static std::vector<std::shared_ptr<SocketFactory>> factories
+{
+	std::make_shared<TemplateSocketFactory<PROTOCOL_TCP, ROLE_CLIENT, MODE_STREAM, TCPClientSocket >> (),
+	std::make_shared<TemplateSocketFactory<PROTOCOL_TCP, ROLE_SERVER, MODE_STREAM, TCPServerSocket >> (),
+	std::make_shared<TemplateSocketFactory<PROTOCOL_UDP, ROLE_CLIENT, MODE_DATAGRAM, UDPClientSocket >> (),
+	std::make_shared<TemplateSocketFactory<PROTOCOL_UDP, ROLE_SERVER, MODE_DATAGRAM, UDPServerSocket >> (),
+	std::make_shared<TemplateSocketFactory<PROTOCOL_SCTP, ROLE_CLIENT, MODE_STREAM, SCTPClientSocket >> (),
+	std::make_shared<TemplateSocketFactory<PROTOCOL_SCTP, ROLE_SERVER, MODE_STREAM, UDPClientSocket >> (), // TODO: correct class
+	std::make_shared<TemplateSocketFactory<PROTOCOL_UDS, ROLE_CLIENT, MODE_STREAM, UDSClientSocket >> (),
+	std::make_shared<TemplateSocketFactory<PROTOCOL_UDS, ROLE_CLIENT, MODE_DATAGRAM, UDSClientSocket >> (), // TODO: correct class
+	std::make_shared<TemplateSocketFactory<PROTOCOL_UDS, ROLE_SERVER, MODE_STREAM, UDSClientSocket >> (), // TODO: correct class
+	std::make_shared<TemplateSocketFactory<PROTOCOL_UDS, ROLE_SERVER, MODE_DATAGRAM, UDSClientSocket >> (), // TODO: correct class
+};
+
+std::shared_ptr<SocketFactory> SocketFactory::find(const SocketOptions& options) {
+	for (auto f : factories) if (f->canHandle(options)) return f;
+	throw std::logic_error("Unable to find a SocketFactory"); // TODO: add relevant options?
+}
+
+
+}
+}
+}