Function isIntegrityMetadata

lib/validator/component_name.cpp:117–163

integrity-metadata = *WSP hash-with-options *(1*WSP hash-with-options) *WSP hash-with-options = hash-expression *("?" option-expression) hash-expression = hash-algorithm "-" base64-value hash-algorithm = "sha256" / "sha384" / "sha512" base64-value = *VCHAR (visible chars, no whitespace)

// hash-algorithm      = "sha256" / "sha384" / "sha512"
// base64-value        = *VCHAR (visible chars, no whitespace)
bool isIntegrityMetadata(std::string_view Input) {
  while (!Input.empty() && Input.front() == ' ')
    Input.remove_prefix(1);
  while (!Input.empty() && Input.back() == ' ')
    Input.remove_suffix(1);
  if (Input.empty())
    return false;

  bool HasToken = false;
  while (!Input.empty()) {
    while (!Input.empty() && Input.front() == ' ')
      Input.remove_prefix(1);
    if (Input.empty())
      break;

    size_t TokenEnd = Input.find(' ');
    std::string_view Token =
        (TokenEnd == Input.npos) ? Input : Input.substr(0, TokenEnd);
    Input =
        (TokenEnd == Input.npos) ? std::string_view{} : Input.substr(TokenEnd);

    size_t OptPos = Token.find('?');
    std::string_view HashExpr =
        (OptPos == Token.npos) ? Token : Token.substr(0, OptPos);

    bool ValidAlgo = false;
    static constexpr std::string_view Algos[3] = {"sha256-", "sha384-",
                                                  "sha512-"};
    for (auto AlgoSV : Algos) {
      if (HashExpr.size() > AlgoSV.size() &&
          HashExpr.substr(0, AlgoSV.size()) == AlgoSV) {
        auto Value = HashExpr.substr(AlgoSV.size());
        if (std::all_of(Value.begin(), Value.end(),
                        [](char C) { return C >= 0x21 && C <= 0x7E; })) {
          ValidAlgo = true;
        }
        break;
      }
    }
    if (!ValidAlgo)
      return false;

    HasToken = true;
  }

  return HasToken;
}

// Parses a non-negative integer without leading zeros.
// Returns the end position, or npos on failure.