Base64 update with absl::Base64

[ping-sun]

Related Issue: #12694

Description:
This pull request helps to replace the current Base64::encode/decode with absl::Base64.
The current code base provide base64 encoding and decoding with or without padding. Abseil has supported to do that. To be more specific:
Base64::encode(src_data, src_len, padding=true) can be replaced with absl::Base64Escape(std::string src).
Base64::encode(src_data, src_len, padding=false) can be replaced with absl::Base64WebSafeEscape(std::string src).
Base64Url::encode(src_data, src_len) can be replaced with absl::Base64WebSafeEscape(std::string src).

Base64::decode(std::string src) can be replaced with absl::Base64Unescape(src, *dst).
Base64::decodeWithoutPadding(std::string src) can be replaced with absl::Base64WebSafeUnescape(src, *dst).
Base64Url::decode(std::string src) can be replaced with absl::Base64WebSafeEscape(std::string src).

The doc of absl::Base64: https://github.com/abseil/abseil-cpp/blob/master/absl/strings/escaping.h

[lizan]

If we can't completely replace and remove Base64::encode/decode, it might not worth for the replacement. Can you just replace the implementation of Base64::encode/decode?

[ping-sun]

If we can't completely replace and remove Base64::encode/decode, it might not worth for the replacement. Can you just replace the implementation of Base64::encode/decode?

Sure, Thanks for the great idea. I previously thought that we will finally remove the lib of the current Base64 so I just updated the code where it has been used directly. I think your idea is a even better, I will try to replace the implementation of Base64.

[ping-sun]

I have some trouble implementing the Base64::decode

org = "Zh==";
success = absl::Base64Unescape(org, &decoded);
EXPECT_EQ(decoded, "");    // "f"
success = absl::WebSafeBase64Unescape(org, &decoded); 
EXPECT_EQ(decoded, "");    // "f"

The expected value for decode("Zh==") in the test is EMPTY_STRING.
However, I can not get that result neither with a absl::Base64Unescape nor a absl::WebSafeBase64Unescape

[ping-sun]

The current implementation:

std::string Base64::decode(const std::string& input) {
  if (input.length() % 4) {
    return EMPTY_STRING;
  }
  return decodeWithoutPadding(input);
}

std::string Base64::decodeWithoutPadding(absl::string_view input) {
  if (input.empty()) {
    return EMPTY_STRING;
  }
  std::string decoded;
  bool success = absl::Base64Unescape(input, &decoded);
  if (success) {
    return decoded;
  } else {
    return EMPTY_STRING;
  }
}

std::string Base64Url::decode(const std::string& input) {
  if (input.empty()) {
    return EMPTY_STRING;
  }
  std::string decoded;
  bool success = absl::WebSafeBase64Unescape(input, &decoded);
  if (success) {
    return decoded;
  } else {
    return EMPTY_STRING;
  }
}

[ping-sun]

Hi @lizan, I think it might not be possible to remove the original implementation of Base64 Encode/Decode, especially considering the usage of encodeBase/encodeLast and decodeBase/decodeLast for const Buffer::Instance& buffer object. So probably it is not a good idea to replace the current implementation directly with the abseil. What do you think?

[mattklein123]

@ASOPVII if we can't replace it yeah I would say let's just close this for now?

[ping-sun]

@ASOPVII if we can't replace it yeah I would say let's just close this for now?

Sure, I agree~