Implement support for checking bad IPs aka MatchMalwareIP

chrome/browser/safe_browsing/safe_browsing_database.cc

Index: chrome/browser/safe_browsing/safe_browsing_database.cc
diff --git a/chrome/browser/safe_browsing/safe_browsing_database.cc b/chrome/browser/safe_browsing/safe_browsing_database.cc
index 586ee45841db2d6e9d1b19a5c9b00709ede92b11..bd87b89bb132dda31cd83b88002dce981e70fd47 100644
--- a/chrome/browser/safe_browsing/safe_browsing_database.cc
+++ b/chrome/browser/safe_browsing/safe_browsing_database.cc
@@ -27,6 +27,7 @@
 #include "build/build_config.h"
 #include "chrome/browser/safe_browsing/safe_browsing_store_file.h"
 #include "components/safe_browsing_db/prefix_set.h"
+#include "components/safe_browsing_db/v4_protocol_manager_util.h"
 #include "content/public/browser/browser_thread.h"
 #include "crypto/sha2.h"
 #include "net/base/ip_address.h"
@@ -958,12 +959,9 @@ bool SafeBrowsingDatabaseNew::ContainsExtensionPrefixes(
 
 bool SafeBrowsingDatabaseNew::ContainsMalwareIP(const std::string& ip_address) {
   net::IPAddress address;
-  if (!address.AssignFromIPLiteral(ip_address))
+  if (!V4ProtocolManagerUtil::GetIPV6AddressFromString(ip_address, &address)) {

[Nathan Parker, 2016/11/15 00:54:46]

Is there value in updating this (legacy) code?

[vakh (use Gerrit instead), 2016/11/15 01:03:41]

Smaller binary size until we rip out PVer3 completely?

[Scott Hess - ex-Googler, 2016/11/15 01:21:10]

Do you have binary-size metrics to back that up?

I'm not saying it's _not_ smaller.  Just that hand-wavy arguments don't carry
much weight :-).

[vakh (use Gerrit instead), 2016/11/15 01:27:51]

No, but if we leave the same code in two places, isn't it going to be compiled
into the binary twice? Please do correct me if I am wrong here.

A smart compiler may realize that the code is exactly the same and try to
optimize it, but why rely on the compiler when you can easily change that code
and make it more readable in the process?
I seriously didn't realize that this could be considered hand-wavy. Repeated
code == higher binary size, in my mind.

[Scott Hess - ex-Googler, 2016/11/15 01:34:24]

For small functions, it depends on if the various code related to framing and
aligning the new function outweighs the savings in calling the new function. 
Which in turn is dependent on things like inlining, which in turn depends on
whether your compiler is crazy smart or not.

PROBABLY since the functions being called are not available in ip_address.h,
extracting the shared bit like this will be a savings.  But I wouldn't bet more
than like $1 on it, as a lark, because AFAICT the compiler specializes in
destroying my assumptions.

     return false;
-  if (address.IsIPv4())
-    address = net::ConvertIPv4ToIPv4MappedIPv6(address);
-  if (!address.IsIPv6())
-    return false;  // better safe than sorry.
+  }
 
   std::unique_ptr<ReadTransaction> txn = state_manager_.BeginReadTransaction();
   const IPBlacklist* ip_blacklist = txn->ip_blacklist();