remoting: use VerifyHostPinHash() in place on IsPinValid()

remoting/host/mac/me2me_preference_pane.mm

Index: remoting/host/mac/me2me_preference_pane.mm
diff --git a/remoting/host/mac/me2me_preference_pane.mm b/remoting/host/mac/me2me_preference_pane.mm
index de33b8bf500127561dea1a3514b6e68ca5487f81..ab020bdf431e3c294efe47fff70268a7b66e98a9 100644
--- a/remoting/host/mac/me2me_preference_pane.mm
+++ b/remoting/host/mac/me2me_preference_pane.mm
@@ -21,11 +21,11 @@
 #include "base/posix/eintr_wrapper.h"
 #include "remoting/host/constants_mac.h"
 #include "remoting/host/host_config.h"
+#include "remoting/host/pin_hash.h"
 #import "remoting/host/mac/me2me_preference_pane_confirm_pin.h"
 #import "remoting/host/mac/me2me_preference_pane_disable.h"
 #include "third_party/jsoncpp/source/include/json/reader.h"
 #include "third_party/jsoncpp/source/include/json/writer.h"
-#include "third_party/modp_b64/modp_b64.h"
 
 namespace {
 
@@ -46,51 +46,6 @@ bool IsConfigValid(const remoting::JsonHostConfig* config) {
           config->GetString(remoting::kXmppLoginConfigPath, &value));
 }
 
-bool IsPinValid(const std::string& pin, const std::string& host_id,
-                const std::string& host_secret_hash) {
-  // TODO(lambroslambrou): Once the "base" target supports building for 64-bit
-  // on Mac OS X, remove this code and replace it with |VerifyHostPinHash()|
-  // from host/pin_hash.h.
-  size_t separator = host_secret_hash.find(':');
-  if (separator == std::string::npos)
-    return false;
-
-  std::string method = host_secret_hash.substr(0, separator);
-  if (method != "hmac") {
-    NSLog(@"Authentication method '%s' not supported", method.c_str());
-    return false;
-  }
-
-  std::string hash_base64 = host_secret_hash.substr(separator + 1);
-
-  // Convert |hash_base64| to |hash|, based on code from base/base64.cc.
-  int hash_base64_size = static_cast<int>(hash_base64.size());
-  std::string hash;
-  hash.resize(modp_b64_decode_len(hash_base64_size));
-
-  // modp_b64_decode_len() returns at least 1, so hash[0] is safe here.
-  int hash_size = modp_b64_decode(&(hash[0]), hash_base64.data(),
-                                  hash_base64_size);
-  if (hash_size < 0) {
-    NSLog(@"Failed to parse host_secret_hash");
-    return false;
-  }
-  hash.resize(hash_size);
-
-  std::string computed_hash;
-  computed_hash.resize(CC_SHA256_DIGEST_LENGTH);
-
-  CCHmac(kCCHmacAlgSHA256,
-         host_id.data(), host_id.size(),
-         pin.data(), pin.size(),
-         &(computed_hash[0]));
-
-  // Normally, a constant-time comparison function would be used, but it is
-  // unnecessary here as the "secret" is already readable by the user
-  // supplying input to this routine.
-  return computed_hash == hash;
-}
-
 }  // namespace
 
 // These methods are copied from base/mac, but with the logging changed to use
@@ -341,7 +296,7 @@ std::string JsonHostConfig::GetSerializedData() const {
     [self showError];
     return;
   }
-  if (!IsPinValid(pin_utf8, host_id, host_secret_hash)) {
+  if (!remoting::VerifyHostPinHash(pin_utf8, host_id, host_secret_hash)) {

[nicholss, 2016/02/03 22:33:45]

The arguments are flipped here. I will have a CL to correct this in a few
minutes.

     [self showIncorrectPinMessage];
     return;
   }