DoQ responses are length-prefixed per RFC 9250. The resolver previously
assumed the stream always contained at least two bytes and unpacked from
buf[2:], which could panic on truncated or malicious replies.
Validate the prefix against the bytes read, return a clear error, and
retire the connection from the pool on framing failure. Unpack only the
slice declared by the prefix so a short read cannot be misinterpreted as
a full message.
Add regression coverage with a small test server that returns malformed
raw payloads (empty, one byte, prefix-only, prefix larger than payload).
Go's default is already TLS 1.2+ (since Go 1.18), but making this
explicit satisfies RFC 7858/9250 recommendations and makes the security
intent clear for auditors.
Added more descriptive error messages for TLS certificate verification
failures across DoH, DoT, DoQ, and DoH3 protocols. The error messages
now include:
- Certificate subject information
- Issuer organization details
- Common name of the certificate
This helps users and developers better understand certificate validation
failures by providing specific details about the untrusted certificate,
rather than just a generic "unknown authority" message.
Example error message change:
Before: "certificate signed by unknown authority"
After: "certificate signed by unknown authority: TestCA, TestOrg, TestIssuerOrg"
Cuong Manh Le