net/Resolver: replace with more advanced implementation

The new implementation is copied from another project and is
BSD-licensed.  It is exception-safe and can parse IPv6 scope ids with
interface names.

1 files changed, 142 insertions, 0 deletions

diff --git a/src/net/AddressInfo.hxx b/src/net/AddressInfo.hxx
new file mode 100644
index 000000000..63f8ebe64
--- /dev/null
+++ b/src/net/AddressInfo.hxx
@@ -0,0 +1,142 @@
+/*
+ * Copyright (C) 2016-2017 Max Kellermann <max.kellermann@gmail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
+ * FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef NET_ADDRESS_INFO_HXX
+#define NET_ADDRESS_INFO_HXX
+
+#include "SocketAddress.hxx"
+
+#include <algorithm>
+#include <utility>
+
+#ifdef _WIN32
+#include <ws2tcpip.h>
+#else
+#include <netdb.h>
+#endif
+
+class AddressInfo : addrinfo {
+	/* this class cannot be instantiated, it can only be cast from
+	   a struct addrinfo pointer */
+	AddressInfo() = delete;
+	~AddressInfo() = delete;
+
+public:
+	constexpr int GetFamily() const {
+		return ai_family;
+	}
+
+	constexpr int GetType() const {
+		return ai_socktype;
+	}
+
+	constexpr int GetProtocol() const {
+		return ai_protocol;
+	}
+
+	constexpr operator SocketAddress() const {
+		return {ai_addr, (SocketAddress::size_type)ai_addrlen};
+	}
+};
+
+class AddressInfoList {
+	struct addrinfo *value = nullptr;
+
+public:
+	AddressInfoList() = default;
+	explicit AddressInfoList(struct addrinfo *_value):value(_value) {}
+
+	AddressInfoList(AddressInfoList &&src)
+		:value(std::exchange(src.value, nullptr)) {}
+
+	~AddressInfoList() {
+		freeaddrinfo(value);
+	}
+
+	AddressInfoList &operator=(AddressInfoList &&src) {
+		std::swap(value, src.value);
+		return *this;
+	}
+
+	bool empty() const {
+		return value == nullptr;
+	}
+
+	const AddressInfo &front() const {
+		return *(const AddressInfo *)value;
+	}
+
+	/**
+	 * Pick the best address from the list, e.g. prefer IPv6 over
+	 * IPv4 (if both are available).  We do this because binding
+	 * to an IPv6 wildcard address also allows accepting IPv4
+	 * connections.
+	 */
+	gcc_pure
+	const AddressInfo &GetBest() const;
+
+	class const_iterator {
+		struct addrinfo *cursor;
+
+	public:
+		explicit constexpr const_iterator(struct addrinfo *_cursor)
+			:cursor(_cursor) {}
+
+		constexpr bool operator==(const_iterator other) const {
+			return cursor == other.cursor;
+		}
+
+		constexpr bool operator!=(const_iterator other) const {
+			return cursor != other.cursor;
+		}
+
+		const_iterator &operator++() {
+			cursor = cursor->ai_next;
+			return *this;
+		}
+
+		constexpr const AddressInfo &operator*() const {
+			return *(const AddressInfo *)cursor;
+		}
+
+		constexpr const AddressInfo *operator->() const {
+			return (const AddressInfo *)cursor;
+		}
+	};
+
+	const_iterator begin() const {
+		return const_iterator(value);
+	}
+
+	const_iterator end() const {
+		return const_iterator(nullptr);
+	}
+};
+
+#endif