Revert 225303 "Added NetworkInterface::network_prefix."

> Added NetworkInterface::network_prefix.
> 
> BUG=295997
> NOTRY=true
> 
> Review URL: https://codereview.chromium.org/23726043

TBR=vitalybuka@chromium.org

Review URL: https://codereview.chromium.org/24530007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@225326 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 24 insertions, 0 deletions

diff --git a/net/dns/address_sorter_posix.cc b/net/dns/address_sorter_posix.cc
index 514a00f..8d87774 100644
--- a/net/dns/address_sorter_posix.cc
+++ b/net/dns/address_sorter_posix.cc
@@ -175,6 +175,30 @@ AddressSorterPosix::PolicyEntry kDefaultIPv4ScopeTable[] = {
   { { }, 0, AddressSorterPosix::SCOPE_GLOBAL },
 };
 
+// Returns number of matching initial bits between the addresses |a1| and |a2|.
+unsigned CommonPrefixLength(const IPAddressNumber& a1,
+                            const IPAddressNumber& a2) {
+  DCHECK_EQ(a1.size(), a2.size());
+  for (size_t i = 0; i < a1.size(); ++i) {
+    unsigned diff = a1[i] ^ a2[i];
+    if (!diff)
+      continue;
+    for (unsigned j = 0; j < CHAR_BIT; ++j) {
+      if (diff & (1 << (CHAR_BIT - 1)))
+        return i * CHAR_BIT + j;
+      diff <<= 1;
+    }
+    NOTREACHED();
+  }
+  return a1.size() * CHAR_BIT;
+}
+
+// Computes the number of leading 1-bits in |mask|.
+unsigned MaskPrefixLength(const IPAddressNumber& mask) {
+  IPAddressNumber all_ones(mask.size(), 0xFF);
+  return CommonPrefixLength(mask, all_ones);
+}
+
 struct DestinationInfo {
   IPAddressNumber address;
   AddressSorterPosix::AddressScope scope;