rtc_base/win32.cc - src.git - Git at Google

 /*
  *  Copyright 2004 The WebRTC Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */

 #include "rtc_base/win32.h"

 #include <winsock2.h>
 #include <ws2tcpip.h>
 #include <algorithm>

 #include "rtc_base/arraysize.h"
 #include "rtc_base/byte_order.h"
 #include "rtc_base/checks.h"
 #include "rtc_base/logging.h"
 #include "rtc_base/string_utils.h"

 namespace rtc {

 // Helper function declarations for inet_ntop/inet_pton.
 static const char* inet_ntop_v4(const void* src, char* dst, socklen_t size);
 static const char* inet_ntop_v6(const void* src, char* dst, socklen_t size);
 static int inet_pton_v4(const char* src, void* dst);
 static int inet_pton_v6(const char* src, void* dst);

 // Implementation of inet_ntop (create a printable representation of an
 // ip address). XP doesn't have its own inet_ntop, and
 // WSAAddressToString requires both IPv6 to be  installed and for Winsock
 // to be initialized.
 const char* win32_inet_ntop(int af,
                             const void* src,
                             char* dst,
                             socklen_t size) {
   if (!src || !dst) {
     return nullptr;
   }
   switch (af) {
     case AF_INET: {
       return inet_ntop_v4(src, dst, size);
     }
     case AF_INET6: {
       return inet_ntop_v6(src, dst, size);
     }
   }
   return nullptr;
 }

 // As above, but for inet_pton. Implements inet_pton for v4 and v6.
 // Note that our inet_ntop will output normal 'dotted' v4 addresses only.
 int win32_inet_pton(int af, const char* src, void* dst) {
   if (!src || !dst) {
     return 0;
   }
   if (af == AF_INET) {
     return inet_pton_v4(src, dst);
   } else if (af == AF_INET6) {
     return inet_pton_v6(src, dst);
   }
   return -1;
 }

 // Helper function for inet_ntop for IPv4 addresses.
 // Outputs "dotted-quad" decimal notation.
 const char* inet_ntop_v4(const void* src, char* dst, socklen_t size) {
   if (size < INET_ADDRSTRLEN) {
     return nullptr;
   }
   const struct in_addr* as_in_addr =
       reinterpret_cast<const struct in_addr*>(src);
   snprintf(dst, size, "%d.%d.%d.%d", as_in_addr->S_un.S_un_b.s_b1,
            as_in_addr->S_un.S_un_b.s_b2, as_in_addr->S_un.S_un_b.s_b3,
            as_in_addr->S_un.S_un_b.s_b4);
   return dst;
 }

 // Helper function for inet_ntop for IPv6 addresses.
 const char* inet_ntop_v6(const void* src, char* dst, socklen_t size) {
   if (size < INET6_ADDRSTRLEN) {
     return nullptr;
   }
   const uint16_t* as_shorts = reinterpret_cast<const uint16_t*>(src);
   int runpos[8];
   int current = 1;
   int max = 0;
   int maxpos = -1;
   int run_array_size = arraysize(runpos);
   // Run over the address marking runs of 0s.
   for (int i = 0; i < run_array_size; ++i) {
     if (as_shorts[i] == 0) {
       runpos[i] = current;
       if (current > max) {
         maxpos = i;
         max = current;
       }
       ++current;
     } else {
       runpos[i] = -1;
       current = 1;
     }
   }

   if (max > 0) {
     int tmpmax = maxpos;
     // Run back through, setting -1 for all but the longest run.
     for (int i = run_array_size - 1; i >= 0; i--) {
       if (i > tmpmax) {
         runpos[i] = -1;
       } else if (runpos[i] == -1) {
         // We're less than maxpos, we hit a -1, so the 'good' run is done.
         // Setting tmpmax -1 means all remaining positions get set to -1.
         tmpmax = -1;
       }
     }
   }

   char* cursor = dst;
   // Print IPv4 compatible and IPv4 mapped addresses using the IPv4 helper.
   // These addresses have an initial run of either eight zero-bytes followed
   // by 0xFFFF, or an initial run of ten zero-bytes.
   if (runpos[0] == 1 &&
       (maxpos == 5 || (maxpos == 4 && as_shorts[5] == 0xFFFF))) {
     *cursor++ = ':';
     *cursor++ = ':';
     if (maxpos == 4) {
       cursor += snprintf(cursor, INET6_ADDRSTRLEN - 2, "ffff:");
     }
     const struct in_addr* as_v4 =
         reinterpret_cast<const struct in_addr*>(&(as_shorts[6]));
     inet_ntop_v4(as_v4, cursor,
                  static_cast<socklen_t>(INET6_ADDRSTRLEN - (cursor - dst)));
   } else {
     for (int i = 0; i < run_array_size; ++i) {
       if (runpos[i] == -1) {
         cursor += snprintf(cursor, INET6_ADDRSTRLEN - (cursor - dst), "%x",
                            NetworkToHost16(as_shorts[i]));
         if (i != 7 && runpos[i + 1] != 1) {
           *cursor++ = ':';
         }
       } else if (runpos[i] == 1) {
         // Entered the run; print the colons and skip the run.
         *cursor++ = ':';
         *cursor++ = ':';
         i += (max - 1);
       }
     }
   }
   return dst;
 }

 // Helper function for inet_pton for IPv4 addresses.
 // |src| points to a character string containing an IPv4 network address in
 // dotted-decimal format, "ddd.ddd.ddd.ddd", where ddd is a decimal number
 // of up to three digits in the range 0 to 255.
 // The address is converted and copied to dst,
 // which must be sizeof(struct in_addr) (4) bytes (32 bits) long.
 int inet_pton_v4(const char* src, void* dst) {
   const int kIpv4AddressSize = 4;
   int found = 0;
   const char* src_pos = src;
   unsigned char result[kIpv4AddressSize] = {0};

   while (*src_pos != '\0') {
     // strtol won't treat whitespace characters in the begining as an error,
     // so check to ensure this is started with digit before passing to strtol.
     if (!isdigit(*src_pos)) {
       return 0;
     }
     char* end_pos;
     long value = strtol(src_pos, &end_pos, 10);
     if (value < 0 || value > 255 || src_pos == end_pos) {
       return 0;
     }
     ++found;
     if (found > kIpv4AddressSize) {
       return 0;
     }
     result[found - 1] = static_cast<unsigned char>(value);
     src_pos = end_pos;
     if (*src_pos == '.') {
       // There's more.
       ++src_pos;
     } else if (*src_pos != '\0') {
       // If it's neither '.' nor '\0' then return fail.
       return 0;
     }
   }
   if (found != kIpv4AddressSize) {
     return 0;
   }
   memcpy(dst, result, sizeof(result));
   return 1;
 }

 // Helper function for inet_pton for IPv6 addresses.
 int inet_pton_v6(const char* src, void* dst) {
   // sscanf will pick any other invalid chars up, but it parses 0xnnnn as hex.
   // Check for literal x in the input string.
   const char* readcursor = src;
   char c = *readcursor++;
   while (c) {
     if (c == 'x') {
       return 0;
     }
     c = *readcursor++;
   }
   readcursor = src;

   struct in6_addr an_addr;
   memset(&an_addr, 0, sizeof(an_addr));

   uint16_t* addr_cursor = reinterpret_cast<uint16_t*>(&an_addr.s6_addr[0]);
   uint16_t* addr_end = reinterpret_cast<uint16_t*>(&an_addr.s6_addr[16]);
   bool seencompressed = false;

   // Addresses that start with "::" (i.e., a run of initial zeros) or
   // "::ffff:" can potentially be IPv4 mapped or compatibility addresses.
   // These have dotted-style IPv4 addresses on the end (e.g. "::192.168.7.1").
   if (*readcursor == ':' && *(readcursor + 1) == ':' &&
       *(readcursor + 2) != 0) {
     // Check for periods, which we'll take as a sign of v4 addresses.
     const char* addrstart = readcursor + 2;
     if (strchr(addrstart, '.')) {
       const char* colon = strchr(addrstart, ':');
       if (colon) {
         uint16_t a_short;
         int bytesread = 0;
         if (sscanf(addrstart, "%hx%n", &a_short, &bytesread) != 1 ||
             a_short != 0xFFFF || bytesread != 4) {
           // Colons + periods means has to be ::ffff:a.b.c.d. But it wasn't.
           return 0;
         } else {
           an_addr.s6_addr[10] = 0xFF;
           an_addr.s6_addr[11] = 0xFF;
           addrstart = colon + 1;
         }
       }
       struct in_addr v4;
       if (inet_pton_v4(addrstart, &v4.s_addr)) {
         memcpy(&an_addr.s6_addr[12], &v4, sizeof(v4));
         memcpy(dst, &an_addr, sizeof(an_addr));
         return 1;
       } else {
         // Invalid v4 address.
         return 0;
       }
     }
   }

   // For addresses without a trailing IPv4 component ('normal' IPv6 addresses).
   while (*readcursor != 0 && addr_cursor < addr_end) {
     if (*readcursor == ':') {
       if (*(readcursor + 1) == ':') {
         if (seencompressed) {
           // Can only have one compressed run of zeroes ("::") per address.
           return 0;
         }
         // Hit a compressed run. Count colons to figure out how much of the
         // address is skipped.
         readcursor += 2;
         const char* coloncounter = readcursor;
         int coloncount = 0;
         if (*coloncounter == 0) {
           // Special case - trailing ::.
           addr_cursor = addr_end;
         } else {
           while (*coloncounter) {
             if (*coloncounter == ':') {
               ++coloncount;
             }
             ++coloncounter;
           }
           // (coloncount + 1) is the number of shorts left in the address.
           // If this number is greater than the number of available shorts, the
           // address is malformed.
           if (coloncount + 1 > addr_end - addr_cursor) {
             return 0;
           }
           addr_cursor = addr_end - (coloncount + 1);
           seencompressed = true;
         }
       } else {
         ++readcursor;
       }
     } else {
       uint16_t word;
       int bytesread = 0;
       if (sscanf(readcursor, "%4hx%n", &word, &bytesread) != 1) {
         return 0;
       } else {
         *addr_cursor = HostToNetwork16(word);
         ++addr_cursor;
         readcursor += bytesread;
         if (*readcursor != ':' && *readcursor != '\0') {
           return 0;
         }
       }
     }
   }

   if (*readcursor != '\0' || addr_cursor < addr_end) {
     // Catches addresses too short or too long.
     return 0;
   }
   memcpy(dst, &an_addr, sizeof(an_addr));
   return 1;
 }

 bool Utf8ToWindowsFilename(const std::string& utf8, std::wstring* filename) {
   // TODO: Integrate into fileutils.h
   // TODO: Handle wide and non-wide cases via TCHAR?
   // TODO: Skip \\?\ processing if the length is not > MAX_PATH?
   // TODO: Write unittests

   // Convert to Utf16
   int wlen =
       ::MultiByteToWideChar(CP_UTF8, 0, utf8.c_str(),
                             static_cast<int>(utf8.length() + 1), nullptr, 0);
   if (0 == wlen) {
     return false;
   }
   wchar_t* wfilename = STACK_ARRAY(wchar_t, wlen);
   if (0 == ::MultiByteToWideChar(CP_UTF8, 0, utf8.c_str(),
                                  static_cast<int>(utf8.length() + 1), wfilename,
                                  wlen)) {
     return false;
   }
   // Replace forward slashes with backslashes
   std::replace(wfilename, wfilename + wlen, L'/', L'\\');
 #if defined(WINUWP)
   // WinUWP sandboxed store applications require the paths to remain as
   // relative paths.
   filename->assign(wfilename);
 #else
   // Convert to complete filename
   DWORD full_len = ::GetFullPathName(wfilename, 0, nullptr, nullptr);
   if (0 == full_len) {
     return false;
   }
   wchar_t* filepart = nullptr;
   wchar_t* full_filename = STACK_ARRAY(wchar_t, full_len + 6);
   wchar_t* start = full_filename + 6;
   if (0 == ::GetFullPathName(wfilename, full_len, start, &filepart)) {
     return false;
   }
   // Add long-path prefix
   const wchar_t kLongPathPrefix[] = L"\\\\?\\UNC";
   if ((start[0] != L'\\') || (start[1] != L'\\')) {
     // Non-unc path:     <pathname>
     //      Becomes: \\?\<pathname>
     start -= 4;
     RTC_DCHECK(start >= full_filename);
     memcpy(start, kLongPathPrefix, 4 * sizeof(wchar_t));
   } else if (start[2] != L'?') {
     // Unc path:       \\<server>\<pathname>
     //  Becomes: \\?\UNC\<server>\<pathname>
     start -= 6;
     RTC_DCHECK(start >= full_filename);
     memcpy(start, kLongPathPrefix, 7 * sizeof(wchar_t));
   } else {
     // Already in long-path form.
   }
   filename->assign(start);
 #endif  // defined(WINUWP)

   return true;
 }

 // Windows UWP applications cannot obtain versioning information from
 // the sandbox with intention (as behehaviour based on OS versioning rather
 // than feature discovery / compilation flags is discoraged and Windows
 // 10 is living continously updated version unlike previous versions
 // of Windows).
 #if !defined(WINUWP)

 bool GetOsVersion(int* major, int* minor, int* build) {
   OSVERSIONINFO info = {0};
   info.dwOSVersionInfoSize = sizeof(info);
   if (GetVersionEx(&info)) {
     if (major)
       *major = info.dwMajorVersion;
     if (minor)
       *minor = info.dwMinorVersion;
     if (build)
       *build = info.dwBuildNumber;
     return true;
   }
   return false;
 }

 bool GetCurrentProcessIntegrityLevel(int* level) {
   bool ret = false;
   HANDLE process = ::GetCurrentProcess(), token;
   if (OpenProcessToken(process, TOKEN_QUERY | TOKEN_QUERY_SOURCE, &token)) {
     DWORD size;
     if (!GetTokenInformation(token, TokenIntegrityLevel, nullptr, 0, &size) &&
         GetLastError() == ERROR_INSUFFICIENT_BUFFER) {
       char* buf = STACK_ARRAY(char, size);
       TOKEN_MANDATORY_LABEL* til =
           reinterpret_cast<TOKEN_MANDATORY_LABEL*>(buf);
       if (GetTokenInformation(token, TokenIntegrityLevel, til, size, &size)) {
         DWORD count = *GetSidSubAuthorityCount(til->Label.Sid);
         *level = *GetSidSubAuthority(til->Label.Sid, count - 1);
         ret = true;
       }
     }
     CloseHandle(token);
   }
   return ret;
 }

 #endif  // !defined(WINUWP)

 }  // namespace rtc
	/*
	* Copyright 2004 The WebRTC Project Authors. All rights reserved.
	*
	* Use of this source code is governed by a BSD-style license
	* that can be found in the LICENSE file in the root of the source
	* tree. An additional intellectual property rights grant can be found
	* in the file PATENTS. All contributing project authors may
	* be found in the AUTHORS file in the root of the source tree.
	*/

	#include "rtc_base/win32.h"

	#include <winsock2.h>
	#include <ws2tcpip.h>
	#include <algorithm>

	#include "rtc_base/arraysize.h"
	#include "rtc_base/byte_order.h"
	#include "rtc_base/checks.h"
	#include "rtc_base/logging.h"
	#include "rtc_base/string_utils.h"

	namespace rtc {

	// Helper function declarations for inet_ntop/inet_pton.
	static const char* inet_ntop_v4(const void* src, char* dst, socklen_t size);
	static const char* inet_ntop_v6(const void* src, char* dst, socklen_t size);
	static int inet_pton_v4(const char* src, void* dst);
	static int inet_pton_v6(const char* src, void* dst);

	// Implementation of inet_ntop (create a printable representation of an
	// ip address). XP doesn't have its own inet_ntop, and
	// WSAAddressToString requires both IPv6 to be installed and for Winsock
	// to be initialized.
	const char* win32_inet_ntop(int af,
	const void* src,
	char* dst,
	socklen_t size) {
	if (!src \|\| !dst) {
	return nullptr;
	}
	switch (af) {
	case AF_INET: {
	return inet_ntop_v4(src, dst, size);
	}
	case AF_INET6: {
	return inet_ntop_v6(src, dst, size);
	}
	}
	return nullptr;
	}

	// As above, but for inet_pton. Implements inet_pton for v4 and v6.
	// Note that our inet_ntop will output normal 'dotted' v4 addresses only.
	int win32_inet_pton(int af, const char* src, void* dst) {
	if (!src \|\| !dst) {
	return 0;
	}
	if (af == AF_INET) {
	return inet_pton_v4(src, dst);
	} else if (af == AF_INET6) {
	return inet_pton_v6(src, dst);
	}
	return -1;
	}

	// Helper function for inet_ntop for IPv4 addresses.
	// Outputs "dotted-quad" decimal notation.
	const char* inet_ntop_v4(const void* src, char* dst, socklen_t size) {
	if (size < INET_ADDRSTRLEN) {
	return nullptr;
	}
	const struct in_addr* as_in_addr =
	reinterpret_cast<const struct in_addr*>(src);
	snprintf(dst, size, "%d.%d.%d.%d", as_in_addr->S_un.S_un_b.s_b1,
	as_in_addr->S_un.S_un_b.s_b2, as_in_addr->S_un.S_un_b.s_b3,
	as_in_addr->S_un.S_un_b.s_b4);
	return dst;
	}

	// Helper function for inet_ntop for IPv6 addresses.
	const char* inet_ntop_v6(const void* src, char* dst, socklen_t size) {
	if (size < INET6_ADDRSTRLEN) {
	return nullptr;
	}
	const uint16_t* as_shorts = reinterpret_cast<const uint16_t*>(src);
	int runpos[8];
	int current = 1;
	int max = 0;
	int maxpos = -1;
	int run_array_size = arraysize(runpos);
	// Run over the address marking runs of 0s.
	for (int i = 0; i < run_array_size; ++i) {
	if (as_shorts[i] == 0) {
	runpos[i] = current;
	if (current > max) {
	maxpos = i;
	max = current;
	}
	++current;
	} else {
	runpos[i] = -1;
	current = 1;
	}
	}

	if (max > 0) {
	int tmpmax = maxpos;
	// Run back through, setting -1 for all but the longest run.
	for (int i = run_array_size - 1; i >= 0; i--) {
	if (i > tmpmax) {
	runpos[i] = -1;
	} else if (runpos[i] == -1) {
	// We're less than maxpos, we hit a -1, so the 'good' run is done.
	// Setting tmpmax -1 means all remaining positions get set to -1.
	tmpmax = -1;
	}
	}
	}

	char* cursor = dst;
	// Print IPv4 compatible and IPv4 mapped addresses using the IPv4 helper.
	// These addresses have an initial run of either eight zero-bytes followed
	// by 0xFFFF, or an initial run of ten zero-bytes.
	if (runpos[0] == 1 &&
	(maxpos == 5 \|\| (maxpos == 4 && as_shorts[5] == 0xFFFF))) {
	*cursor++ = ':';
	*cursor++ = ':';
	if (maxpos == 4) {
	cursor += snprintf(cursor, INET6_ADDRSTRLEN - 2, "ffff:");
	}
	const struct in_addr* as_v4 =
	reinterpret_cast<const struct in_addr*>(&(as_shorts[6]));
	inet_ntop_v4(as_v4, cursor,
	static_cast<socklen_t>(INET6_ADDRSTRLEN - (cursor - dst)));
	} else {
	for (int i = 0; i < run_array_size; ++i) {
	if (runpos[i] == -1) {
	cursor += snprintf(cursor, INET6_ADDRSTRLEN - (cursor - dst), "%x",
	NetworkToHost16(as_shorts[i]));
	if (i != 7 && runpos[i + 1] != 1) {
	*cursor++ = ':';
	}
	} else if (runpos[i] == 1) {
	// Entered the run; print the colons and skip the run.
	*cursor++ = ':';
	*cursor++ = ':';
	i += (max - 1);
	}
	}
	}
	return dst;
	}

	// Helper function for inet_pton for IPv4 addresses.
	// \|src\| points to a character string containing an IPv4 network address in
	// dotted-decimal format, "ddd.ddd.ddd.ddd", where ddd is a decimal number
	// of up to three digits in the range 0 to 255.
	// The address is converted and copied to dst,
	// which must be sizeof(struct in_addr) (4) bytes (32 bits) long.
	int inet_pton_v4(const char* src, void* dst) {
	const int kIpv4AddressSize = 4;
	int found = 0;
	const char* src_pos = src;
	unsigned char result[kIpv4AddressSize] = {0};

	while (*src_pos != '\0') {
	// strtol won't treat whitespace characters in the begining as an error,
	// so check to ensure this is started with digit before passing to strtol.
	if (!isdigit(*src_pos)) {
	return 0;
	}
	char* end_pos;
	long value = strtol(src_pos, &end_pos, 10);
	if (value < 0 \|\| value > 255 \|\| src_pos == end_pos) {
	return 0;
	}
	++found;
	if (found > kIpv4AddressSize) {
	return 0;
	}
	result[found - 1] = static_cast<unsigned char>(value);
	src_pos = end_pos;
	if (*src_pos == '.') {
	// There's more.
	++src_pos;
	} else if (*src_pos != '\0') {
	// If it's neither '.' nor '\0' then return fail.
	return 0;
	}
	}
	if (found != kIpv4AddressSize) {
	return 0;
	}
	memcpy(dst, result, sizeof(result));
	return 1;
	}

	// Helper function for inet_pton for IPv6 addresses.
	int inet_pton_v6(const char* src, void* dst) {
	// sscanf will pick any other invalid chars up, but it parses 0xnnnn as hex.
	// Check for literal x in the input string.
	const char* readcursor = src;
	char c = *readcursor++;
	while (c) {
	if (c == 'x') {
	return 0;
	}
	c = *readcursor++;
	}
	readcursor = src;

	struct in6_addr an_addr;
	memset(&an_addr, 0, sizeof(an_addr));

	uint16_t* addr_cursor = reinterpret_cast<uint16_t*>(&an_addr.s6_addr[0]);
	uint16_t* addr_end = reinterpret_cast<uint16_t*>(&an_addr.s6_addr[16]);
	bool seencompressed = false;

	// Addresses that start with "::" (i.e., a run of initial zeros) or
	// "::ffff:" can potentially be IPv4 mapped or compatibility addresses.
	// These have dotted-style IPv4 addresses on the end (e.g. "::192.168.7.1").
	if (readcursor == ':' && (readcursor + 1) == ':' &&
	*(readcursor + 2) != 0) {
	// Check for periods, which we'll take as a sign of v4 addresses.
	const char* addrstart = readcursor + 2;
	if (strchr(addrstart, '.')) {
	const char* colon = strchr(addrstart, ':');
	if (colon) {
	uint16_t a_short;
	int bytesread = 0;
	if (sscanf(addrstart, "%hx%n", &a_short, &bytesread) != 1 \|\|
	a_short != 0xFFFF \|\| bytesread != 4) {
	// Colons + periods means has to be ::ffff:a.b.c.d. But it wasn't.
	return 0;
	} else {
	an_addr.s6_addr[10] = 0xFF;
	an_addr.s6_addr[11] = 0xFF;
	addrstart = colon + 1;
	}
	}
	struct in_addr v4;
	if (inet_pton_v4(addrstart, &v4.s_addr)) {
	memcpy(&an_addr.s6_addr[12], &v4, sizeof(v4));
	memcpy(dst, &an_addr, sizeof(an_addr));
	return 1;
	} else {
	// Invalid v4 address.
	return 0;
	}
	}
	}

	// For addresses without a trailing IPv4 component ('normal' IPv6 addresses).
	while (*readcursor != 0 && addr_cursor < addr_end) {
	if (*readcursor == ':') {
	if (*(readcursor + 1) == ':') {
	if (seencompressed) {
	// Can only have one compressed run of zeroes ("::") per address.
	return 0;
	}
	// Hit a compressed run. Count colons to figure out how much of the
	// address is skipped.
	readcursor += 2;
	const char* coloncounter = readcursor;
	int coloncount = 0;
	if (*coloncounter == 0) {
	// Special case - trailing ::.
	addr_cursor = addr_end;
	} else {
	while (*coloncounter) {
	if (*coloncounter == ':') {
	++coloncount;
	}
	++coloncounter;
	}
	// (coloncount + 1) is the number of shorts left in the address.
	// If this number is greater than the number of available shorts, the
	// address is malformed.
	if (coloncount + 1 > addr_end - addr_cursor) {
	return 0;
	}
	addr_cursor = addr_end - (coloncount + 1);
	seencompressed = true;
	}
	} else {
	++readcursor;
	}
	} else {
	uint16_t word;
	int bytesread = 0;
	if (sscanf(readcursor, "%4hx%n", &word, &bytesread) != 1) {
	return 0;
	} else {
	*addr_cursor = HostToNetwork16(word);
	++addr_cursor;
	readcursor += bytesread;
	if (readcursor != ':' && readcursor != '\0') {
	return 0;
	}
	}
	}
	}

	if (*readcursor != '\0' \|\| addr_cursor < addr_end) {
	// Catches addresses too short or too long.
	return 0;
	}
	memcpy(dst, &an_addr, sizeof(an_addr));
	return 1;
	}

	bool Utf8ToWindowsFilename(const std::string& utf8, std::wstring* filename) {
	// TODO: Integrate into fileutils.h
	// TODO: Handle wide and non-wide cases via TCHAR?
	// TODO: Skip \\?\ processing if the length is not > MAX_PATH?
	// TODO: Write unittests

	// Convert to Utf16
	int wlen =
	::MultiByteToWideChar(CP_UTF8, 0, utf8.c_str(),
	static_cast<int>(utf8.length() + 1), nullptr, 0);
	if (0 == wlen) {
	return false;
	}
	wchar_t* wfilename = STACK_ARRAY(wchar_t, wlen);
	if (0 == ::MultiByteToWideChar(CP_UTF8, 0, utf8.c_str(),
	static_cast<int>(utf8.length() + 1), wfilename,
	wlen)) {
	return false;
	}
	// Replace forward slashes with backslashes
	std::replace(wfilename, wfilename + wlen, L'/', L'\\');
	#if defined(WINUWP)
	// WinUWP sandboxed store applications require the paths to remain as
	// relative paths.
	filename->assign(wfilename);
	#else
	// Convert to complete filename
	DWORD full_len = ::GetFullPathName(wfilename, 0, nullptr, nullptr);
	if (0 == full_len) {
	return false;
	}
	wchar_t* filepart = nullptr;
	wchar_t* full_filename = STACK_ARRAY(wchar_t, full_len + 6);
	wchar_t* start = full_filename + 6;
	if (0 == ::GetFullPathName(wfilename, full_len, start, &filepart)) {
	return false;
	}
	// Add long-path prefix
	const wchar_t kLongPathPrefix[] = L"\\\\?\\UNC";
	if ((start[0] != L'\\') \|\| (start[1] != L'\\')) {
	// Non-unc path: <pathname>
	// Becomes: \\?\<pathname>
	start -= 4;
	RTC_DCHECK(start >= full_filename);
	memcpy(start, kLongPathPrefix, 4 * sizeof(wchar_t));
	} else if (start[2] != L'?') {
	// Unc path: \\<server>\<pathname>
	// Becomes: \\?\UNC\<server>\<pathname>
	start -= 6;
	RTC_DCHECK(start >= full_filename);
	memcpy(start, kLongPathPrefix, 7 * sizeof(wchar_t));
	} else {
	// Already in long-path form.
	}
	filename->assign(start);
	#endif // defined(WINUWP)

	return true;
	}

	// Windows UWP applications cannot obtain versioning information from
	// the sandbox with intention (as behehaviour based on OS versioning rather
	// than feature discovery / compilation flags is discoraged and Windows
	// 10 is living continously updated version unlike previous versions
	// of Windows).
	#if !defined(WINUWP)

	bool GetOsVersion(int* major, int* minor, int* build) {
	OSVERSIONINFO info = {0};
	info.dwOSVersionInfoSize = sizeof(info);
	if (GetVersionEx(&info)) {
	if (major)
	*major = info.dwMajorVersion;
	if (minor)
	*minor = info.dwMinorVersion;
	if (build)
	*build = info.dwBuildNumber;
	return true;
	}
	return false;
	}

	bool GetCurrentProcessIntegrityLevel(int* level) {
	bool ret = false;
	HANDLE process = ::GetCurrentProcess(), token;
	if (OpenProcessToken(process, TOKEN_QUERY \| TOKEN_QUERY_SOURCE, &token)) {
	DWORD size;
	if (!GetTokenInformation(token, TokenIntegrityLevel, nullptr, 0, &size) &&
	GetLastError() == ERROR_INSUFFICIENT_BUFFER) {
	char* buf = STACK_ARRAY(char, size);
	TOKEN_MANDATORY_LABEL* til =
	reinterpret_cast<TOKEN_MANDATORY_LABEL*>(buf);
	if (GetTokenInformation(token, TokenIntegrityLevel, til, size, &size)) {
	DWORD count = *GetSidSubAuthorityCount(til->Label.Sid);
	level = GetSidSubAuthority(til->Label.Sid, count - 1);
	ret = true;
	}
	}
	CloseHandle(token);
	}
	return ret;
	}

	#endif // !defined(WINUWP)

	} // namespace rtc