Revert 39998 - Revert 39996 Refine IPv6 probe to require that the client has...

net/base/net_util.cc

Index: net/base/net_util.cc
===================================================================
--- net/base/net_util.cc	(revision 40097)
+++ net/base/net_util.cc	(working copy)
@@ -21,9 +21,11 @@
 #include <ws2tcpip.h>
 #include <wspiapi.h>  // Needed for Win2k compat.
 #elif defined(OS_POSIX)
+#include <fcntl.h>
+#include <ifaddrs.h>
 #include <netdb.h>
+#include <net/if.h>
 #include <sys/socket.h>
-#include <fcntl.h>
 #endif
 
 #include "base/base64.h"
@@ -257,7 +259,7 @@
 
 bool DecodeWord(const std::string& encoded_word,
                 const std::string& referrer_charset,
-                bool *is_rfc2047,
+                bool* is_rfc2047,
                 std::string* output) {
   if (!IsStringASCII(encoded_word)) {
     // Try UTF-8, referrer_charset and the native OS default charset in turn.
@@ -1541,15 +1543,21 @@
 enum IPv6SupportStatus {
   IPV6_CANNOT_CREATE_SOCKETS,
   IPV6_CAN_CREATE_SOCKETS,
+  IPV6_GETIFADDRS_FAILED,
+  IPV6_GLOBAL_ADDRESS_MISSING,
+  IPV6_GLOBAL_ADDRESS_PRESENT,
   IPV6_SUPPORT_MAX  // Bounding values for enumeration.
 };
 
 static void IPv6SupportResults(IPv6SupportStatus result) {
   static bool run_once = false;
-  if (run_once)
-    return;
-  run_once = true;
-  UMA_HISTOGRAM_ENUMERATION("Net.IPv6Status", result, IPV6_SUPPORT_MAX);
+  if (run_once) {
+    run_once = true;
+    UMA_HISTOGRAM_ENUMERATION("Net.IPv6Status", result, IPV6_SUPPORT_MAX);
+  } else {
+    UMA_HISTOGRAM_ENUMERATION("Net.IPv6Status_retest", result,
+                              IPV6_SUPPORT_MAX);
+  }
 }
 
 // TODO(jar): The following is a simple estimate of IPv6 support.  We may need
@@ -1557,27 +1565,58 @@
 // static
 bool IPv6Supported() {
 #if defined(OS_POSIX)
-  int test_socket;
-
-  test_socket = socket(AF_INET6, SOCK_STREAM, 0);
+  int test_socket = socket(AF_INET6, SOCK_STREAM, 0);
   if (test_socket == -1) {
     IPv6SupportResults(IPV6_CANNOT_CREATE_SOCKETS);
     return false;
   }
+  close(test_socket);
 
-  close(test_socket);
-  IPv6SupportResults(IPV6_CAN_CREATE_SOCKETS);
+  // Check to see if any interface has a IPv6 address.
+  struct ifaddrs* interface_addr = NULL;
+  int rv = getifaddrs(&interface_addr);
+  if (rv != 0) {
+     IPv6SupportResults(IPV6_GETIFADDRS_FAILED);
+     return true;  // Don't yet block IPv6.
+  }
+
+  bool found_ipv6 = false;
+  for (struct ifaddrs* interface = interface_addr;
+       interface != NULL;
+       interface = interface->ifa_next) {
+    if (!(IFF_UP & interface->ifa_flags))
+      continue;
+    if (IFF_LOOPBACK & interface->ifa_flags)
+      continue;
+    struct sockaddr* addr = interface->ifa_addr;
+    if (!addr)
+      continue;
+    if (addr->sa_family != AF_INET6)
+      continue;
+    // Safe cast since this is AF_INET6.
+    struct sockaddr_in6* addr_in6 =
+      reinterpret_cast<struct sockaddr_in6*>(addr);
+    struct in6_addr* sin6_addr = &addr_in6->sin6_addr;
+    if (IN6_IS_ADDR_LOOPBACK(sin6_addr) || IN6_IS_ADDR_LINKLOCAL(sin6_addr))
+      continue;
+    found_ipv6 = true;
+    break;
+  }
+  freeifaddrs(interface_addr);
+  if (!found_ipv6) {
+    IPv6SupportResults(IPV6_GLOBAL_ADDRESS_MISSING);
+    return false;
+  }
+
+  IPv6SupportResults(IPV6_GLOBAL_ADDRESS_PRESENT);
   return true;
 #elif defined(OS_WIN)
   EnsureWinsockInit();
-  SOCKET test_socket;
-
-  test_socket = socket(AF_INET6, SOCK_STREAM, 0);
+  SOCKET test_socket = socket(AF_INET6, SOCK_STREAM, 0);
   if (test_socket == INVALID_SOCKET) {
     IPv6SupportResults(IPV6_CANNOT_CREATE_SOCKETS);
     return false;
   }
-
   closesocket(test_socket);
   IPv6SupportResults(IPV6_CAN_CREATE_SOCKETS);
   return true;
@@ -1587,5 +1626,4 @@
 #endif  // defined(various platforms)
 }
 
-
 }  // namespace net