// readSignedMessage reads a possibly signed message if mdin is non-zero then
// that structure is updated and returned. Otherwise a fresh MessageDetails is
// used.
func readSignedMessage(packets *packet.Reader, mdin *MessageDetails, keyring KeyRing) (md *MessageDetails, err error) {
if mdin == nil {
mdin = new(MessageDetails)
}
md = mdin
var p packet.Packet
var h hash.Hash
var wrappedHash hash.Hash
FindLiteralData:
for {
p, err = packets.Next()
if err != nil {
return nil, err
}
switch p := p.(type) {
case *packet.Compressed:
if err := packets.Push(p.Body); err != nil {
return nil, err
}
case *packet.OnePassSignature:
if !p.IsLast {
return nil, errors.UnsupportedError("nested signatures")
}
h, wrappedHash, err = hashForSignature(p.Hash, p.SigType)
if err != nil {
md = nil
return
}
md.IsSigned = true
md.SignedByKeyId = p.KeyId
keys := keyring.KeysByIdUsage(p.KeyId, packet.KeyFlagSign)
if len(keys) > 0 {
md.SignedBy = &keys[0]
}
case *packet.LiteralData:
md.LiteralData = p
break FindLiteralData
}
}
if md.SignedBy != nil {
md.UnverifiedBody = &signatureCheckReader{packets, h, wrappedHash, md}
} else if md.decrypted != nil {
md.UnverifiedBody = checkReader{md}
} else {
md.UnverifiedBody = md.LiteralData.Body
}
return md, nil
}
