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// Copyright (C) MongoDB, Inc. 2017-present.
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may
// not use this file except in compliance with the License. You may obtain
// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
//+build gssapi
//+build linux darwin
package gssapi
/*
#cgo linux CFLAGS: -DGOOS_linux
#cgo linux LDFLAGS: -lgssapi_krb5 -lkrb5
#cgo darwin CFLAGS: -DGOOS_darwin
#cgo darwin LDFLAGS: -framework GSS
#include "gss_wrapper.h"
*/
import "C"
import (
"fmt"
"runtime"
"strings"
"unsafe"
)
// New creates a new SaslClient. The target parameter should be a hostname with no port.
func New(target, username, password string, passwordSet bool, props map[string]string) (*SaslClient, error) {
serviceName := "mongodb"
for key, value := range props {
switch strings.ToUpper(key) {
case "CANONICALIZE_HOST_NAME":
return nil, fmt.Errorf("CANONICALIZE_HOST_NAME is not supported when using gssapi on %s", runtime.GOOS)
case "SERVICE_REALM":
return nil, fmt.Errorf("SERVICE_REALM is not supported when using gssapi on %s", runtime.GOOS)
case "SERVICE_NAME":
serviceName = value
case "SERVICE_HOST":
target = value
default:
return nil, fmt.Errorf("unknown mechanism property %s", key)
}
}
servicePrincipalName := fmt.Sprintf("%s@%s", serviceName, target)
return &SaslClient{
servicePrincipalName: servicePrincipalName,
username: username,
password: password,
passwordSet: passwordSet,
}, nil
}
type SaslClient struct {
servicePrincipalName string
username string
password string
passwordSet bool
// state
state C.gssapi_client_state
contextComplete bool
done bool
}
func (sc *SaslClient) Close() {
C.gssapi_client_destroy(&sc.state)
}
func (sc *SaslClient) Start() (string, []byte, error) {
const mechName = "GSSAPI"
cservicePrincipalName := C.CString(sc.servicePrincipalName)
defer C.free(unsafe.Pointer(cservicePrincipalName))
var cusername *C.char
var cpassword *C.char
if sc.username != "" {
cusername = C.CString(sc.username)
defer C.free(unsafe.Pointer(cusername))
if sc.passwordSet {
cpassword = C.CString(sc.password)
defer C.free(unsafe.Pointer(cpassword))
}
}
status := C.gssapi_client_init(&sc.state, cservicePrincipalName, cusername, cpassword)
if status != C.GSSAPI_OK {
return mechName, nil, sc.getError("unable to initialize client")
}
payload, err := sc.Next(nil)
return mechName, payload, err
}
func (sc *SaslClient) Next(challenge []byte) ([]byte, error) {
var buf unsafe.Pointer
var bufLen C.size_t
var outBuf unsafe.Pointer
var outBufLen C.size_t
if sc.contextComplete {
if sc.username == "" {
var cusername *C.char
status := C.gssapi_client_username(&sc.state, &cusername)
if status != C.GSSAPI_OK {
return nil, sc.getError("unable to acquire username")
}
defer C.free(unsafe.Pointer(cusername))
sc.username = C.GoString((*C.char)(unsafe.Pointer(cusername)))
}
bytes := append([]byte{1, 0, 0, 0}, []byte(sc.username)...)
buf = unsafe.Pointer(&bytes[0])
bufLen = C.size_t(len(bytes))
status := C.gssapi_client_wrap_msg(&sc.state, buf, bufLen, &outBuf, &outBufLen)
if status != C.GSSAPI_OK {
return nil, sc.getError("unable to wrap authz")
}
sc.done = true
} else {
if len(challenge) > 0 {
buf = unsafe.Pointer(&challenge[0])
bufLen = C.size_t(len(challenge))
}
status := C.gssapi_client_negotiate(&sc.state, buf, bufLen, &outBuf, &outBufLen)
switch status {
case C.GSSAPI_OK:
sc.contextComplete = true
case C.GSSAPI_CONTINUE:
default:
return nil, sc.getError("unable to negotiate with server")
}
}
if outBuf != nil {
defer C.free(outBuf)
}
return C.GoBytes(outBuf, C.int(outBufLen)), nil
}
func (sc *SaslClient) Completed() bool {
return sc.done
}
func (sc *SaslClient) getError(prefix string) error {
var desc *C.char
status := C.gssapi_error_desc(sc.state.maj_stat, sc.state.min_stat, &desc)
if status != C.GSSAPI_OK {
if desc != nil {
C.free(unsafe.Pointer(desc))
}
return fmt.Errorf("%s: (%v, %v)", prefix, sc.state.maj_stat, sc.state.min_stat)
}
defer C.free(unsafe.Pointer(desc))
return fmt.Errorf("%s: %v(%v,%v)", prefix, C.GoString(desc), int32(sc.state.maj_stat), int32(sc.state.min_stat))
}
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