Fix IPAddress::ToSensitiveString() to avoid dependency on inet_ntop().

webrtc/base/ipaddress.cc

 /*
  *  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.
  */
 
@@ skipping 10 matching lines @@
 #include <arpa/inet.h>
 #include <netdb.h>
 #include <unistd.h>
 #endif
 
 #include <stdio.h>
 
 #include "webrtc/base/ipaddress.h"
 #include "webrtc/base/byteorder.h"
 #include "webrtc/base/checks.h"
+#include "webrtc/base/logging.h"
 #include "webrtc/base/nethelpers.h"
-#include "webrtc/base/logging.h"
+#include "webrtc/base/stringutils.h"
 #include "webrtc/base/win32.h"
 
 namespace rtc {
 
 // Prefixes used for categorizing IPv6 addresses.
 static const in6_addr kV4MappedPrefix = {{{0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
                                            0xFF, 0xFF, 0}}};
 static const in6_addr k6To4Prefix = {{{0x20, 0x02, 0}}};
 static const in6_addr kTeredoPrefix = {{{0x20, 0x01, 0x00, 0x00}}};
 static const in6_addr kV4CompatibilityPrefix = {{{0}}};
@@ skipping 86 matching lines @@
 
 std::string IPAddress::ToString() const {
   if (family_ != AF_INET && family_ != AF_INET6) {
     return std::string();
   }
   char buf[INET6_ADDRSTRLEN] = {0};
   const void* src = &u_.ip4;
   if (family_ == AF_INET6) {
     src = &u_.ip6;
   }
   if (!rtc::inet_ntop(family_, src, buf, sizeof(buf))) {

[pthatcher1, 2016/01/13 22:25:23]

Would it be a good idea to remove the dependency on inet_netop altogether?

[Sergey Ulanov, 2016/01/13 22:47:42]

Maybe, but I think it should be done separately from this fix.
FWIW there is an implementation of inet_ntop() in win32.cc, because inet_ntop()
didn't exist on windows before Vista.

     return std::string();
   }
   return std::string(buf);
 }
 
 std::string IPAddress::ToSensitiveString() const {
 #if !defined(NDEBUG)
   // Return non-stripped in debug.
   return ToString();
 #else
   switch (family_) {
     case AF_INET: {
       std::string address = ToString();
       size_t find_pos = address.rfind('.');
       if (find_pos == std::string::npos)
         return std::string();
       address.resize(find_pos);
       address += ".x";
       return address;
     }
     case AF_INET6: {
-      // Remove the last 5 groups (80 bits).
-      std::string address = TruncateIP(*this, 128 - 80).ToString();
-
-      // If all three remaining groups are written out explicitly in the string,
-      // remove one of the two trailing colons before appending the stripped
-      // groups as "x"s. There should be max 4 colons (2 between the 3 groups +
-      // 2 trailing) in the truncated address string.
-      size_t number_of_colons = std::count(address.begin(), address.end(), ':');
-      RTC_CHECK_LE(number_of_colons, 4u);
-      if (number_of_colons > 3)
-        address.resize(address.length() - 1);
-
-      return address + "x:x:x:x:x";
+      std::string result;
+      result.resize(40);

[pthatcher1, 2016/01/13 22:25:23]

Why 40?

Truncated, it could only be 25.  Are you just playing it safe?

Also, please at least comment on it, or make a named constant for it (like
kMaxIpv6AddressStringLength).

[Sergey Ulanov, 2016/01/13 22:47:42]

Changed it to INET6_ADDRSTRLEN. (it's set to 46, for ipv4-mapped addresses)

+      in6_addr addr = ipv6_address();
+      size_t len =
+          rtc::sprintfn(&(result[0]), result.size(), "%x:%x:%x:x:x:x:x:x",
+                        (addr.s6_addr[0] << 8) + addr.s6_addr[1],
+                        (addr.s6_addr[2] << 8) + addr.s6_addr[3],
+                        (addr.s6_addr[4] << 8) + addr.s6_addr[5]);

[pthatcher1, 2016/01/13 22:25:23]

Would it be worth the little extra code to make "::" instead of ":0:" in the
string?

[Sergey Ulanov, 2016/01/13 22:47:42]

I don't think so. It would make this code more complicated, but it makes only
3-char difference only in some addresses and the result isn't easier to read.

+      result.resize(len);
+      return result;
     }
   }
   return std::string();
 #endif
 }
 
 IPAddress IPAddress::Normalized() const {
   if (family_ != AF_INET6) {
     return *this;
   }
@@ skipping 334 matching lines @@
   if (family == AF_INET) {
     return rtc::IPAddress(INADDR_ANY);
   }
   if (family == AF_INET6) {
     return rtc::IPAddress(in6addr_any);
   }
   return rtc::IPAddress();
 }
 
 }  // Namespace rtc