add version, domain and workstation fields

Add version support from jh125486
Add workstation and domain support from jh125486
Enable to extract domain from username

negotiate_message.go

@@ -3,29 +3,61 @@ package ntlmssp
 import (
 	"bytes"
 	"encoding/binary"
+	"errors"
+	"strings"
 )
 
+const expMsgBodyLen = 40
+
 type negotiateMessageFields struct {
-	messageHeader
-	NegotiateFlags negotiateFlags
+        messageHeader
+        NegotiateFlags negotiateFlags
+
+        Domain      varField
+        Workstation varField
+
+        Version
 }
 
+var defaultFlags = negotiateFlagNTLMSSPNEGOTIATETARGETINFO |
+        negotiateFlagNTLMSSPNEGOTIATE56 |
+        negotiateFlagNTLMSSPNEGOTIATE128 |
+        negotiateFlagNTLMSSPNEGOTIATEUNICODE
+
 //NewNegotiateMessage creates a new NEGOTIATE message with the
 //flags that this package supports.
-func NewNegotiateMessage() []byte {
-	m := negotiateMessageFields{
-		messageHeader: newMessageHeader(1),
-	}
+func NewNegotiateMessage(domainName, workstationName string) ([]byte, error) {
+        payloadOffset := expMsgBodyLen
+        flags := defaultFlags
 
-	m.NegotiateFlags = negotiateFlagNTLMSSPREQUESTTARGET |
-		negotiateFlagNTLMSSPNEGOTIATENTLM |
-		negotiateFlagNTLMSSPNEGOTIATEALWAYSSIGN |
-		negotiateFlagNTLMSSPNEGOTIATEUNICODE
+        if domainName != "" {
+                flags |= negotiateFlagNTLMSSPNEGOTIATEOEMDOMAINSUPPLIED
+        }
 
-	b := bytes.Buffer{}
-	err := binary.Write(&b, binary.LittleEndian, &m)
-	if err != nil {
-		panic(err)
-	}
-	return b.Bytes()
+        if workstationName != "" {
+                flags |= negotiateFlagNTLMSSPNEGOTIATEOEMWORKSTATIONSUPPLIED
+        }
+
+        msg := negotiateMessageFields{
+                messageHeader:  newMessageHeader(1),
+                NegotiateFlags: flags,
+                Domain:         newVarField(&payloadOffset, len(domainName)),
+                Workstation:    newVarField(&payloadOffset, len(workstationName)),
+                Version:        DefaultVersion(),
+        }
+
+        b := bytes.Buffer{}
+        if err := binary.Write(&b, binary.LittleEndian, &msg); err != nil {
+                return nil, err
+        }
+        if b.Len() != expMsgBodyLen {
+                return nil, errors.New("incorrect body length")
+        }
+
+        payload := strings.ToUpper(domainName + workstationName)
+        if _, err := b.WriteString(payload); err != nil {
+                return nil, err
+        }
+
+        return b.Bytes(), nil
 }