[bug] Incorrect Base64 encoding used for Basic Auth header

[ximocok628]

sing/protocol/http/handshake.go

Line 45 in ed51f65

userPassword, _ := base64.URLEncoding.DecodeString(authorization[6:])

The current implementation of Basic Authentication incorrectly uses base64.URLEncoding to decode the Proxy-Authorization header. According to RFC 7617, the credentials (user-id:password) must be encoded using the standard Base64 alphabet.