Merge commit '86cc97e55fe346502462284d2e636a2b3708163e' as 'Sources/OpenVPN3'

2026-04-24 00:00:05 +08:00 · 2020-02-24 14:43:11 +03:00
parent 133b3756e6 86cc97e55f
commit 32f1555929
655 changed files with 146468 additions and 0 deletions
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+//    OpenVPN -- An application to securely tunnel IP networks
+//               over a single port, with support for SSL/TLS-based
+//               session authentication and key exchange,
+//               packet encryption, packet authentication, and
+//               packet compression.
+//
+//    Copyright (C) 2012-2017 OpenVPN Inc.
+//
+//    This program is free software: you can redistribute it and/or modify
+//    it under the terms of the GNU Affero General Public License Version 3
+//    as published by the Free Software Foundation.
+//
+//    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 Affero General Public License for more details.
+//
+//    You should have received a copy of the GNU Affero General Public License
+//    along with this program in the COPYING file.
+//    If not, see <http://www.gnu.org/licenses/>.
+
+#pragma once
+
+#include <openvpn/common/endian.hpp>
+#include <openvpn/ip/ipcommon.hpp>
+
+namespace openvpn {
+
+#pragma pack(push)
+#pragma pack(1)
+
+  struct TCPHeader {
+    static unsigned int length(const std::uint8_t doff_res)
+    {
+      return ((doff_res) & 0xF0) >> 2;
+    }
+
+    std::uint16_t   source;
+    std::uint16_t   dest;
+    std::uint32_t   seq;
+    std::uint32_t   ack_seq;
+    std::uint8_t    doff_res;
+    std::uint8_t    flags;
+    std::uint16_t   window;
+    std::uint16_t   check;
+    std::uint16_t   urgent_p;
+
+    // helper enum to parse options in TCP header
+    enum {
+      OPT_EOL       = 0,
+      OPT_NOP       = 1,
+      OPT_MAXSEG    = 2,
+      OPTLEN_MAXSEG = 4
+    };
+
+    enum {
+      FLAG_SYN      = 1 << 1
+    };
+  };
+
+#pragma pack(pop)
+
+  /*
+   * The following routine is used to update an
+   * internet checksum.  "acc" is a 32-bit
+   * accumulation of all the changes to the
+   * checksum (adding in old 16-bit words and
+   * subtracting out new words), and "cksum"
+   * is the checksum value to be updated.
+   */
+  inline void tcp_adjust_checksum(int acc, std::uint16_t& cksum)
+  {
+    int _acc = acc;
+    _acc += cksum;
+    if (_acc < 0)
+      {
+	_acc = -_acc;
+	_acc = (_acc >> 16) + (_acc & 0xffff);
+	_acc += _acc >> 16;
+	cksum = (uint16_t)~_acc;
+      }
+    else
+      {
+	_acc = (_acc >> 16) + (_acc & 0xffff);
+	_acc += _acc >> 16;
+	cksum = (uint16_t)_acc;
+      }
+  }
+}
+