This is a VERY rough version of a Go SPF validator. It's invoked like this:
danny@MacBook-Pro ~ » gospfquery -id="danny@banno.com" -ip-address="147.202.96.4"
Your SPF record is allowed to send from 147.202.96.4 for domain banno.com
danny@MacBook-Pro ~ » gospfquery -id="danny@banno.com" -ip-address="147.202.97.4"
The IP (147.202.97.4) was not found as a valid sender for your SPF record, but your "ALL" record is SoftFail, so sending would be permitted
danny@MacBook-Pro ~ » gospfquery -id="danny@amazon.com" -ip-address="147.202.97.4"
The IP (147.202.97.4) was not found as a valid sender for your SPF record, and your "ALL" record is Fail, so sending would NOT be permittedThis does not implement REDIRECT, PTR, or EXISTS. The checking for the "ALL" record is very rough. It also turns all IPv6 records that lack a hostmask into a /128, because I don't know anything about IPv6 addresses. It turns IP4: records without a hostmask into a /32.
PRs welcome.