No logging information on token verification process

[andreaceccanti]

The scitokens-cpp library provides no logging about the reasons behind a token verification failure. This makes debugging authorization problems complex.

[bbockelm]

@djw8605 - can you take a look at this?

I believe, for the Python library, we hooked into the underlying standard Python logging system. Perhaps we can ask users to provide a callback that they implement (and ship a default to log to stdout)?

[djw8605]

The functions themselves provide error text as a returned string. For example:

scitokens-cpp/src/scitokens.h

Line 87 in 6e293ad

int scitoken_deserialize(const char *value, SciToken *token, char const* const* allowed_issuers, char **err_msg);

The error is returned in the error_msg variable. You are correct, the library doesn't log anything to stdout, but it does provide error messages back to the calling code.

We could ship the log to stdout? Or, we can rely on the calling code to log the errors, as we do in xrootd-scitokens:

https://github.com/scitokens/xrootd-scitokens/blob/124062e496def27bd7d47be2ff8853458236f2c8/src/scitokens.cpp#L353-L360