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// Copyright 2013-2015 Apcera Inc. All rights reserved.
package spnego
import (
"encoding/base64"
"fmt"
"net/http"
"strings"
"github.com/apcera/gssapi"
)
const negotiateScheme = "Negotiate"
// AddSPNEGONegotiate adds a Negotiate header with the value of a serialized
// token to an http header.
func AddSPNEGONegotiate(h http.Header, name string, token *gssapi.Buffer) {
if name == "" {
return
}
v := negotiateScheme
if token.Length() != 0 {
data := token.Bytes()
v = v + " " + base64.StdEncoding.EncodeToString(data)
}
h.Set(name, v)
}
// CheckSPNEGONegotiate checks for the presence of a Negotiate header. If
// present, we return a gssapi Token created from the header value sent to us.
func CheckSPNEGONegotiate(lib *gssapi.Lib, h http.Header, name string) (bool, *gssapi.Buffer) {
var err error
defer func() {
if err != nil {
lib.Debug(fmt.Sprintf("CheckSPNEGONegotiate: %v", err))
}
}()
for _, header := range h[http.CanonicalHeaderKey(name)] {
if len(header) < len(negotiateScheme) {
continue
}
if !strings.EqualFold(header[:len(negotiateScheme)], negotiateScheme) {
continue
}
// Remove the "Negotiate" prefix
normalizedToken := header[len(negotiateScheme):]
// Trim leading and trailing whitespace
normalizedToken = strings.TrimSpace(normalizedToken)
// Remove internal whitespace (some servers insert whitespace every 76 chars)
normalizedToken = strings.Replace(normalizedToken, " ", "", -1)
// Pad to a multiple of 4 chars for base64 (some servers strip trailing padding)
if unpaddedChars := len(normalizedToken) % 4; unpaddedChars != 0 {
normalizedToken += strings.Repeat("=", 4-unpaddedChars)
}
tbytes, err := base64.StdEncoding.DecodeString(normalizedToken)
if err != nil {
continue
}
if len(tbytes) == 0 {
return true, nil
}
token, err := lib.MakeBufferBytes(tbytes)
if err != nil {
continue
}
return true, token
}
return false, nil
}
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