[rac] Use stale libaddressinput data if download fails

third_party/libaddressinput/chromium/cpp/src/validating_util.h

Index: third_party/libaddressinput/chromium/cpp/src/validating_util.h
diff --git a/third_party/libaddressinput/chromium/cpp/src/validating_util.h b/third_party/libaddressinput/chromium/cpp/src/validating_util.h
index 8a9b532df9eb83b2acb114ca79f2ffa0a83317f2..b68391568a51a1c38a9d46394f348ae7a6d323d0 100644
--- a/third_party/libaddressinput/chromium/cpp/src/validating_util.h
+++ b/third_party/libaddressinput/chromium/cpp/src/validating_util.h
@@ -31,21 +31,34 @@ namespace addressinput {
 //    Process(wrapped);
 //
 //    std::string unwrapped = wrapped;
-//    if (ValidatingUtil::UnwrapTimestamp(&unwrapped, time(NULL)) &&
+//    if (ValidatingUtil::TIMESTAMP_VALID ==
+//            ValidatingUtil::UnwrapTimestamp(&unwrapped, time(NULL)) &&
 //        ValidatingUtil::UnwrapChecksum(&unwrapped)) {
 //      Process(unwrapped);
 //    }
 class ValidatingUtil {
  public:
+  // Result of parsing and validating a timestamp.
+  enum TimestampStatus {
+   // The timestamp is present, formatted correctly, valid, and recent.
+    TIMESTAMP_VALID,
+
+    // The timestamp is either missing, incorrectly formatted, or invalid.
+    TIMESTAMP_INVALID,
+
+    // The timestamp is present, formatted correctly, and valid, but stale.
+    TIMESTAMP_STALE
+  };
+
   // Returns |data| with attached checksum and given |timestamp|.
   static std::string Wrap(const std::string& data, time_t timestamp);
 
-  // Strips out the timestamp from |data|. Returns |true| if the timestamp is
-  // present, formatted correctly, valid, and recent with respect to |now|.
-  static bool UnwrapTimestamp(std::string* data, time_t now);
+  // Strips out the timestamp from |data| and validates it with respect to
+  // |now|.
+  static TimestampStatus UnwrapTimestamp(std::string* data, time_t now);

[Evan Stade, 2014/01/22 01:42:12]

I think that UnwrapTimestamp and UnwrapChecksum should be a single function:

static bool UnwrapHeader(const std::string& header, time_t* timestamp);

that returns false if the timestamp is missing or invalid or if the checksum
doesn't validate or is missing or anything, but otherwise returns true and fills
out timestamp. The Retriever can contain the logic of "how old is too old".

[please use gerrit instead, 2014/01/22 23:57:41]

Refactored into:

std::string Wrapper::Wrap(const std::string& data);
bool Wrapper::Unwrap(std::string* data, double* age_in_seconds);

I think that's an improvement on what you suggested, because it hides the time_t
inside of the Wrapper implementation. The logic of "how old is too old" in
Retriever is simple now: compare age_in_seconds to the maximum allowed age.

[Evan Stade, 2014/01/23 00:07:23]

why is double a better way of representing time than time_t?

[please use gerrit instead, 2014/01/23 00:09:00]

The difference between two time_t objects is always a double:

http://www.cplusplus.com/reference/ctime/difftime/

 
-  // Strips out the checksum from |data|. Returns |true| if the checksum is
-  // present, formatted correctly, and valid for this data.
+  // Strips out and validates the checksum from |data|. Returns |true| if the
+  // checksum is present, formatted correctly, and valid for this data.
   static bool UnwrapChecksum(std::string* data);
 };