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Signed-off-by: Avi Deitcher <avi@deitcher.net>
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Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -0,0 +1,83 @@ | ||
package ntlm | ||
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import ( | ||
"bytes" | ||
"errors" | ||
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"github.com/cloudsoda/go-smb2/internal/utf16le" | ||
) | ||
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type ChallengeMessage struct { | ||
raw []byte | ||
flags uint32 | ||
info *targetInfoEncoder | ||
targetName []byte | ||
} | ||
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// Unmarshal parses the ChallengeMessage in cmsg and returns the result. | ||
func UnmarshalChallengeMessage(cmsg, nmsg []byte, targetSPN string) (*ChallengeMessage, error) { | ||
// ChallengeMessage | ||
// 0-8: Signature | ||
// 8-12: MessageType | ||
// 12-20: TargetNameFields | ||
// 20-24: NegotiateFlags | ||
// 24-32: ServerChallenge | ||
// 32-40: _ | ||
// 40-48: TargetInfoFields | ||
// 48-56: Version | ||
// 56-: Payload | ||
if len(cmsg) < 48 { | ||
return nil, errors.New("message length is too short") | ||
} | ||
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if !bytes.Equal(cmsg[:8], signature) { | ||
return nil, errors.New("invalid signature") | ||
} | ||
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if le.Uint32(cmsg[8:12]) != NtLmChallenge { | ||
return nil, errors.New("invalid message type") | ||
} | ||
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flags := le.Uint32(nmsg[12:16]) & le.Uint32(cmsg[20:24]) | ||
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if flags&NTLMSSP_REQUEST_TARGET == 0 { | ||
return nil, errors.New("invalid negotiate flags") | ||
} | ||
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targetNameLen := le.Uint16(cmsg[12:14]) // cmsg.TargetNameLen | ||
targetNameMaxLen := le.Uint16(cmsg[14:16]) // cmsg.TargetNameMaxLen | ||
if targetNameMaxLen < targetNameLen { | ||
return nil, errors.New("invalid target name format") | ||
} | ||
targetNameBufferOffset := le.Uint32(cmsg[16:20]) // cmsg.TargetNameBufferOffset | ||
if len(cmsg) < int(targetNameBufferOffset+uint32(targetNameLen)) { | ||
return nil, errors.New("invalid target name format") | ||
} | ||
targetName := cmsg[targetNameBufferOffset : targetNameBufferOffset+uint32(targetNameLen)] // cmsg.TargetName | ||
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if flags&NTLMSSP_NEGOTIATE_TARGET_INFO == 0 { | ||
return nil, errors.New("invalid negotiate flags") | ||
} | ||
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targetInfoLen := le.Uint16(cmsg[40:42]) // cmsg.TargetInfoLen | ||
targetInfoMaxLen := le.Uint16(cmsg[42:44]) // cmsg.TargetInfoMaxLen | ||
if targetInfoMaxLen < targetInfoLen { | ||
return nil, errors.New("invalid target info format") | ||
} | ||
targetInfoBufferOffset := le.Uint32(cmsg[44:48]) // cmsg.TargetInfoBufferOffset | ||
if len(cmsg) < int(targetInfoBufferOffset+uint32(targetInfoLen)) { | ||
return nil, errors.New("invalid target info format") | ||
} | ||
targetInfo := cmsg[targetInfoBufferOffset : targetInfoBufferOffset+uint32(targetInfoLen)] // cmsg.TargetInfo | ||
info := newTargetInfoEncoder(targetInfo, utf16le.Encode(targetSPN, utf16le.MapCharsNone)) | ||
if info == nil { | ||
return nil, errors.New("invalid target info format") | ||
} | ||
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return &ChallengeMessage{ | ||
raw: cmsg, | ||
flags: flags, | ||
info: info, | ||
targetName: targetName, | ||
}, nil | ||
} |
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