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

webrtc/base/ipaddress.cc

Index: webrtc/base/ipaddress.cc
diff --git a/webrtc/base/ipaddress.cc b/webrtc/base/ipaddress.cc
index c85624d24a7729d28c2f6efe2c0eb1d7243fdcaa..f58d1e09abe02d634d364fbdefdc07a7233f994d 100644
--- a/webrtc/base/ipaddress.cc
+++ b/webrtc/base/ipaddress.cc
@@ -28,8 +28,9 @@
 #include "webrtc/base/ipaddress.h"
 #include "webrtc/base/byteorder.h"
 #include "webrtc/base/checks.h"
-#include "webrtc/base/nethelpers.h"
 #include "webrtc/base/logging.h"
+#include "webrtc/base/nethelpers.h"
+#include "webrtc/base/stringutils.h"
 #include "webrtc/base/win32.h"
 
 namespace rtc {
@@ -158,19 +159,16 @@ std::string IPAddress::ToSensitiveString() const {
       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();