WireGuard for MacOS (#248)

* WireGuard for MacOS
* Fix openvpn block-outside-dns

client/mozilla/pingsender.cpp

@@ -0,0 +1,48 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "pingsender.h"
+
+#include "logger.h"
+
+namespace {
+Logger logger("PingSender");
+}
+
+quint16 PingSender::inetChecksum(const void* data, size_t len) {
+  int nleft, sum;
+  quint16* w;
+  union {
+    quint16 us;
+    quint8 uc[2];
+  } last;
+  quint16 answer;
+
+  nleft = static_cast<int>(len);
+  sum = 0;
+  w = (quint16*)data;
+
+  /*
+   * Our algorithm is simple, using a 32 bit accumulator (sum), we add
+   * sequential 16 bit words to it, and at the end, fold back all the
+   * carry bits from the top 16 bits into the lower 16 bits.
+   */
+  while (nleft > 1) {
+    sum += *w++;
+    nleft -= 2;
+  }
+
+  /* mop up an odd byte, if necessary */
+  if (nleft == 1) {
+    last.uc[0] = *(quint8*)w;
+    last.uc[1] = 0;
+    sum += last.us;
+  }
+
+  /* add back carry outs from top 16 bits to low 16 bits */
+  sum = (sum >> 16) + (sum & 0xffff); /* add hi 16 to low 16 */
+  sum += (sum >> 16);                 /* add carry */
+  answer = ~sum;                      /* truncate to 16 bits */
+  return (answer);
+}