refactor: low level socket tidyups and removal of punning (#1282)

.cspell.json

@@ -148,7 +148,8 @@
 		"nullopt",
 		"chrono",
 		"ciphersuite",
-		"rmap"
+		"rmap",
+		"WSAPOLLFD"
 	],
 	"flagWords": [
 		"hte"

include/dpp/discordvoiceclient.h

@@ -584,6 +584,13 @@ class DPP_EXPORT discord_voice_client : public websocket_client
 	 */
 	dave_version_t dave_version;
 
+	/**
+	 * @brief Destination address for where packets go
+	 * on the UDP socket
+	 */
+	address_t destination{};
+
+
 	/**
 	 * @brief Send data to UDP socket immediately.
 	 * 

include/dpp/dns.h

@@ -31,6 +31,8 @@
 #include <sys/types.h>
 #include <string>
 #include <unordered_map>
+#include <cstring>
+#include <dpp/socket.h>
 
 namespace dpp {
 
@@ -40,23 +42,42 @@ namespace dpp {
 	 */
 	struct dns_cache_entry {
 		/**
-		 * @brief Resolved address information
+		 * @brief Resolved address metadata
 		 */
 		addrinfo addr;
 
 		/**
-		 * @brief Socket address.
-		 * Discord only supports ipv4, but sockaddr_in6 is larger
-		 * than sockaddr_in, sockaddr_storage will hold either. This
-		 * means that if discord ever do support ipv6 we just flip
-		 * one value in dns.cpp and that should be all that is needed.
+		 * @brief Resolved address as string.
+		 * The metadata is needed to know what type of address it is.
+		 * Do not do silly stuff like just looking to see if '.' is in it!
 		 */
-		sockaddr_storage ai_addr;
+		std::string resolved_addr;
 
 		/**
 		 * @brief Time at which this cache entry is invalidated
 		 */
 		time_t expire_timestamp;
+
+		/**
+		 * @brief Get address length
+		 * @return address length
+		 */
+		[[nodiscard]] int size() const;
+
+		/**
+		 * @brief Get the address_t that corresponds to this cache entry
+		 * for use when connecting with ::connect()
+		 * @param port Port number to connect to
+		 * @return address_t prefilled with the IP and port number
+		 */
+		[[nodiscard]] const address_t get_connecting_address(uint16_t port) const;
+
+		/**
+		 * @brief Allocate a socket file descriptor for the given dns address
+		 * @return File descriptor ready for calling connect(), or INVALID_SOCKET
+		 * on failure.
+		 */
+		[[nodiscard]] socket make_connecting_socket() const;
 	};
 
 	/**
@@ -73,4 +94,4 @@ namespace dpp {
 	 * @throw dpp::connection_exception On failure to resolve hostname
 	 */
 	const dns_cache_entry* resolve_hostname(const std::string& hostname, const std::string& port);
-} // namespace dpp
+}

include/dpp/socket.h

@@ -1,17 +1,53 @@
+/************************************************************************************
+ *
+ * D++, A Lightweight C++ library for Discord
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ * Copyright 2021 Craig Edwards and D++ contributors
+ * (https://github.com/brainboxdotcc/DPP/graphs/contributors)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ ************************************************************************************/
 #pragma once
 
+#include <dpp/export.h>
+#ifdef _WIN32
+	#include <WinSock2.h>
+	#include <WS2tcpip.h>
+	#include <io.h>
+	#define poll(fds, nfds, timeout) WSAPoll(fds, nfds, timeout)
+	#define pollfd WSAPOLLFD
+#else
+	#include <netinet/in.h>
+	#include <sys/socket.h>
+	#include <arpa/inet.h>
+#endif
+#include <string_view>
+#include <cstdint>
+
+
 namespace dpp
 {
-	/**
-	 * @brief Represents a socket file descriptor.
-	 * This is used to ensure parity between windows and unix-like systems.
-	 */
+/**
+ * @brief Represents a socket file descriptor.
+ * This is used to ensure parity between windows and unix-like systems.
+ */
 #ifndef _WIN32
 	using socket = int;
 #else
 	using socket = SOCKET;
 #endif
-} // namespace dpp
 
 #ifndef SOCKET_ERROR
 /**
@@ -26,3 +62,92 @@ namespace dpp
  */
 #define INVALID_SOCKET ~0
 #endif
+
+/**
+ * @brief Represents an IPv4 address for use with socket functions such as
+ * bind().
+ *
+ * Avoids type punning with C style casts from sockaddr_in to sockaddr pointers.
+ */
+class DPP_EXPORT address_t {
+	/**
+	 * @brief Internal sockaddr struct
+	 */
+	sockaddr socket_addr{};
+
+public:
+
+	/**
+	 * @brief Create a new address_t
+	 * @param ip IPv4 address
+	 * @param port Port number
+	 * @note Leave both as defaults to create a default bind-to-any setting
+	 */
+	address_t(const std::string_view ip = "0.0.0.0", uint16_t port = 0);
+
+	/**
+	 * @brief Get sockaddr
+	 * @return sockaddr pointer
+	 */
+	[[nodiscard]] sockaddr *get_socket_address();
+
+	/**
+	 * @brief Returns size of sockaddr_in
+	 * @return sockaddr_in size
+	 * @note It is important the size this returns is sizeof(sockaddr_in) not
+	 * sizeof(sockaddr), this is NOT a bug but requirement of C socket functions.
+	 */
+	[[nodiscard]] size_t size();
+
+	/**
+	 * @brief Get the port bound to a file descriptor
+	 * @param fd File descriptor
+	 * @return Port number, or 0 if no port bound
+	 */
+	[[nodiscard]] uint16_t get_port(socket fd);
+};
+
+/**
+ * @brief Allocates a dpp::socket, closing it on destruction
+ */
+struct DPP_EXPORT raii_socket {
+	/**
+	 * @brief File descriptor
+	 */
+	socket fd;
+
+	/**
+	 * @brief Construct a socket.
+	 * Calls socket() and returns a new file descriptor
+	 */
+	raii_socket();
+
+	/**
+	 * @brief Non-copyable
+	 */
+	raii_socket(raii_socket&) = delete;
+
+	/**
+	 * @brief Non-movable
+	 */
+	raii_socket(raii_socket&&) = delete;
+
+	/**
+	 * @brief Non-copyable
+	 */
+	raii_socket operator=(raii_socket&) = delete;
+
+	/**
+	 * @brief Non-movable
+	 */
+	raii_socket operator=(raii_socket&&) = delete;
+
+	/**
+	 * @brief Destructor
+	 * Frees the socket by closing it
+	 */
+	~raii_socket();
+};
+
+
+}