1 files changed, 118 insertions, 0 deletions
diff --git a/xpf.cc b/xpf.cc
new file mode 100644
index 0000000..2db6aaf
--- /dev/null
+++ b/xpf.cc
@@ -0,0 +1,118 @@
+/*
+ * This file is part of PowerDNS or dnsdist.
+ * Copyright -- PowerDNS.COM B.V. and its contributors
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * In addition, for the avoidance of any doubt, permission is granted to
+ * link this program with OpenSSL and to (re)distribute the binaries
+ * produced as the result of such linking.
+ *
+ * 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, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "xpf.hh"
+
+std::string generateXPFPayload(bool tcp, const ComboAddress& source, const ComboAddress& destination)
+{
+  if (source.sin4.sin_family != destination.sin4.sin_family) {
+    throw std::runtime_error("The XPF destination and source addresses must be of the same family");
+  }
+
+  std::string ret;
+  const uint8_t version = source.isIPv4() ? 4 : 6;
+  const uint8_t protocol = tcp ? 6 : 17;
+  const size_t addrSize = source.isIPv4() ? sizeof(source.sin4.sin_addr.s_addr) : sizeof(source.sin6.sin6_addr.s6_addr);
+  const uint16_t sourcePort = source.sin4.sin_port;
+  const uint16_t destinationPort = destination.sin4.sin_port;
+
+  ret.reserve(sizeof(version) + sizeof(protocol) + (addrSize * 2) + sizeof(sourcePort) + sizeof(destinationPort));
+
+  ret.append(reinterpret_cast<const char*>(&version), sizeof(version));
+  ret.append(reinterpret_cast<const char*>(&protocol), sizeof(protocol));
+
+  // We already established source and destination sin_family equivalence
+  if (source.isIPv4()) {
+    assert(addrSize == sizeof(source.sin4.sin_addr.s_addr));
+    ret.append(reinterpret_cast<const char*>(&source.sin4.sin_addr.s_addr), addrSize);
+    assert(addrSize == sizeof(destination.sin4.sin_addr.s_addr));
+    ret.append(reinterpret_cast<const char*>(&destination.sin4.sin_addr.s_addr), addrSize);
+  }
+  else {
+    assert(addrSize == sizeof(source.sin6.sin6_addr.s6_addr));
+    ret.append(reinterpret_cast<const char*>(&source.sin6.sin6_addr.s6_addr), addrSize);
+    assert(addrSize == sizeof(destination.sin6.sin6_addr.s6_addr));
+    ret.append(reinterpret_cast<const char*>(&destination.sin6.sin6_addr.s6_addr), addrSize);
+  }
+
+  ret.append(reinterpret_cast<const char*>(&sourcePort), sizeof(sourcePort));
+  ret.append(reinterpret_cast<const char*>(&destinationPort), sizeof(destinationPort));
+
+  return ret;
+}
+
+bool parseXPFPayload(const char* payload, size_t len, ComboAddress& source, ComboAddress* destination)
+{
+  static const size_t addr4Size = sizeof(source.sin4.sin_addr.s_addr);
+  static const size_t addr6Size = sizeof(source.sin6.sin6_addr.s6_addr);
+  uint8_t version;
+  uint8_t protocol;
+  uint16_t sourcePort;
+  uint16_t destinationPort;
+
+  if (len != (sizeof(version) + sizeof(protocol) + (addr4Size * 2) + sizeof(sourcePort) + sizeof(destinationPort)) &&
+      len != (sizeof(version) + sizeof(protocol) + (addr6Size * 2) + sizeof(sourcePort) + sizeof(destinationPort))) {
+    return false;
+  }
+
+  size_t pos = 0;
+
+  memcpy(&version, payload + pos, sizeof(version));
+  pos += sizeof(version);
+
+  if (version != 4 && version != 6) {
+    return false;
+  }
+
+  memcpy(&protocol, payload + pos, sizeof(protocol));
+  pos += sizeof(protocol);
+
+  if (protocol != 6 && protocol != 17) {
+    return false;
+  }
+
+  const size_t addrSize = version == 4 ? sizeof(source.sin4.sin_addr.s_addr) : sizeof(source.sin6.sin6_addr.s6_addr);
+  if (len - pos != ((addrSize * 2) + sizeof(sourcePort) + sizeof(destinationPort))) {
+    return false;
+  }
+
+  source = makeComboAddressFromRaw(version, payload + pos, addrSize);
+  pos += addrSize;
+  if (destination != nullptr) {
+    *destination = makeComboAddressFromRaw(version, payload + pos, addrSize);
+  }
+  pos += addrSize;
+
+  memcpy(&sourcePort, payload + pos, sizeof(sourcePort));
+  pos += sizeof(sourcePort);
+  source.sin4.sin_port = sourcePort;
+
+  memcpy(&destinationPort, payload + pos, sizeof(destinationPort));
+  pos += sizeof(destinationPort);
+  (void) pos;
+
+  if (destination != nullptr) {
+    destination->sin4.sin_port = destinationPort;
+  }
+
+  return true;
+}