Replace NTLMv1 implementation with a functionally equivalent one.

net/http/http_auth_handler_ntlm_portable.cc

Index: net/http/http_auth_handler_ntlm_portable.cc
diff --git a/net/http/http_auth_handler_ntlm_portable.cc b/net/http/http_auth_handler_ntlm_portable.cc
index 38c73e5cedbd305743938d468c3b48b27119e23b..30f99c0dda6f401befec9dd3efff6b88e085e4e4 100644
--- a/net/http/http_auth_handler_ntlm_portable.cc
+++ b/net/http/http_auth_handler_ntlm_portable.cc
@@ -4,574 +4,19 @@
 
 #include "net/http/http_auth_handler_ntlm.h"
 
-#include <stdlib.h>
-// For gethostname
-#if defined(OS_POSIX)
-#include <unistd.h>
-#elif defined(OS_WIN)
-#include <winsock2.h>
-#endif
-
-#include "base/md5.h"
 #include "base/rand_util.h"
-#include "base/strings/string_util.h"
-#include "base/strings/sys_string_conversions.h"
-#include "base/strings/utf_string_conversions.h"
 #include "net/base/net_errors.h"
 #include "net/base/network_interfaces.h"
-#include "net/ntlm/des.h"
-#include "net/ntlm/md4.h"
 
 namespace net {
 
-// Based on mozilla/security/manager/ssl/src/nsNTLMAuthModule.cpp,
-// CVS rev. 1.14.
-//
-// TODO(wtc):
-// - The IS_BIG_ENDIAN code is not tested.
-// - Enable the logging code or just delete it.
-// - Delete or comment out the LM code, which hasn't been tested and isn't
-//   being used.
-
-/* ***** BEGIN LICENSE BLOCK *****
- * Version: MPL 1.1/GPL 2.0/LGPL 2.1
- *
- * The contents of this file are subject to the Mozilla Public License Version
- * 1.1 (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.mozilla.org/MPL/
- *
- * Software distributed under the License is distributed on an "AS IS" basis,
- * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
- * for the specific language governing rights and limitations under the
- * License.
- *
- * The Original Code is Mozilla.
- *
- * The Initial Developer of the Original Code is IBM Corporation.
- * Portions created by IBM Corporation are Copyright (C) 2003
- * IBM Corporation. All Rights Reserved.
- *
- * Contributor(s):
- *   Darin Fisher <darin@meer.net>
- *
- * Alternatively, the contents of this file may be used under the terms of
- * either the GNU General Public License Version 2 or later (the "GPL"), or
- * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
- * in which case the provisions of the GPL or the LGPL are applicable instead
- * of those above. If you wish to allow use of your version of this file only
- * under the terms of either the GPL or the LGPL, and not to allow others to
- * use your version of this file under the terms of the MPL, indicate your
- * decision by deleting the provisions above and replace them with the notice
- * and other provisions required by the GPL or the LGPL. If you do not delete
- * the provisions above, a recipient may use your version of this file under
- * the terms of any one of the MPL, the GPL or the LGPL.
- *
- * ***** END LICENSE BLOCK ***** */
-
-#if defined(ARCH_CPU_LITTLE_ENDIAN)
-#define IS_LITTLE_ENDIAN 1
-#undef IS_BIG_ENDIAN
-#elif defined(ARCH_CPU_BIG_ENDIAN)
-#define IS_BIG_ENDIAN 1
-#undef IS_LITTLE_ENDIAN
-#else
-#error "Unknown endianness"
-#endif
-
-#define NTLM_LOG(x) ((void)0)
-
-//-----------------------------------------------------------------------------
-// This file contains a cross-platform NTLM authentication implementation. It
-// is based on documentation from: http://davenport.sourceforge.net/ntlm.html
-//-----------------------------------------------------------------------------
-
-enum {
-  NTLM_NegotiateUnicode = 0x00000001,
-  NTLM_NegotiateOEM = 0x00000002,
-  NTLM_RequestTarget = 0x00000004,
-  NTLM_Unknown1 = 0x00000008,
-  NTLM_NegotiateSign = 0x00000010,
-  NTLM_NegotiateSeal = 0x00000020,
-  NTLM_NegotiateDatagramStyle = 0x00000040,
-  NTLM_NegotiateLanManagerKey = 0x00000080,
-  NTLM_NegotiateNetware = 0x00000100,
-  NTLM_NegotiateNTLMKey = 0x00000200,
-  NTLM_Unknown2 = 0x00000400,
-  NTLM_Unknown3 = 0x00000800,
-  NTLM_NegotiateDomainSupplied = 0x00001000,
-  NTLM_NegotiateWorkstationSupplied = 0x00002000,
-  NTLM_NegotiateLocalCall = 0x00004000,
-  NTLM_NegotiateAlwaysSign = 0x00008000,
-  NTLM_TargetTypeDomain = 0x00010000,
-  NTLM_TargetTypeServer = 0x00020000,
-  NTLM_TargetTypeShare = 0x00040000,
-  NTLM_NegotiateNTLM2Key = 0x00080000,
-  NTLM_RequestInitResponse = 0x00100000,
-  NTLM_RequestAcceptResponse = 0x00200000,
-  NTLM_RequestNonNTSessionKey = 0x00400000,
-  NTLM_NegotiateTargetInfo = 0x00800000,
-  NTLM_Unknown4 = 0x01000000,
-  NTLM_Unknown5 = 0x02000000,
-  NTLM_Unknown6 = 0x04000000,
-  NTLM_Unknown7 = 0x08000000,
-  NTLM_Unknown8 = 0x10000000,
-  NTLM_Negotiate128 = 0x20000000,
-  NTLM_NegotiateKeyExchange = 0x40000000,
-  NTLM_Negotiate56 = 0x80000000
-};
-
-// We send these flags with our type 1 message.
-enum {
-  NTLM_TYPE1_FLAGS =
-      (NTLM_NegotiateUnicode | NTLM_NegotiateOEM | NTLM_RequestTarget |
-       NTLM_NegotiateNTLMKey |
-       NTLM_NegotiateAlwaysSign |
-       NTLM_NegotiateNTLM2Key)
-};
-
-static const char NTLM_SIGNATURE[] = "NTLMSSP";
-static const char NTLM_TYPE1_MARKER[] = {0x01, 0x00, 0x00, 0x00};
-static const char NTLM_TYPE2_MARKER[] = {0x02, 0x00, 0x00, 0x00};
-static const char NTLM_TYPE3_MARKER[] = {0x03, 0x00, 0x00, 0x00};
-
-enum {
-  NTLM_TYPE1_HEADER_LEN = 32,
-  NTLM_TYPE2_HEADER_LEN = 32,
-  NTLM_TYPE3_HEADER_LEN = 64,
-
-  LM_HASH_LEN = 16,
-  LM_RESP_LEN = 24,
-
-  NTLM_HASH_LEN = 16,
-  NTLM_RESP_LEN = 24
-};
-
-//-----------------------------------------------------------------------------
-
-#define LogFlags(x) ((void)0)
-#define LogBuf(a, b, c) ((void)0)
-#define LogToken(a, b, c) ((void)0)
-
-//-----------------------------------------------------------------------------
-
-// Byte order swapping.
-#define SWAP16(x) ((((x)&0xff) << 8) | (((x) >> 8) & 0xff))
-#define SWAP32(x) ((SWAP16((x)&0xffff) << 16) | (SWAP16((x) >> 16)))
-
-static void* WriteBytes(void* buf, const void* data, uint32_t data_len) {
-  memcpy(buf, data, data_len);
-  return static_cast<char*>(buf) + data_len;
-}
-
-static void* WriteDWORD(void* buf, uint32_t dword) {
-#ifdef IS_BIG_ENDIAN
-  // NTLM uses little endian on the wire.
-  dword = SWAP32(dword);
-#endif
-  return WriteBytes(buf, &dword, sizeof(dword));
-}
-
-static void* WriteSecBuf(void* buf, uint16_t length, uint32_t offset) {
-#ifdef IS_BIG_ENDIAN
-  length = SWAP16(length);
-  offset = SWAP32(offset);
-#endif
-  // Len: 2 bytes.
-  buf = WriteBytes(buf, &length, sizeof(length));
-  // MaxLen: 2 bytes. The sender should set it to the value of Len. The
-  // recipient must ignore it.
-  buf = WriteBytes(buf, &length, sizeof(length));
-  // BufferOffset: 4 bytes.
-  buf = WriteBytes(buf, &offset, sizeof(offset));
-  return buf;
-}
-
-#ifdef IS_BIG_ENDIAN
-/**
- * WriteUnicodeLE copies a unicode string from one buffer to another.  The
- * resulting unicode string is in little-endian format.  The input string is
- * assumed to be in the native endianness of the local machine.  It is safe
- * to pass the same buffer as both input and output, which is a handy way to
- * convert the unicode buffer to little-endian on big-endian platforms.
- */
-static void* WriteUnicodeLE(void* buf,
-                            const base::char16* str,
-                            uint32_t str_len) {
-  // Convert input string from BE to LE.
-  uint8_t* cursor = static_cast<uint8_t*>(buf);
-  const uint8_t* input = reinterpret_cast<const uint8_t*>(str);
-  for (uint32_t i = 0; i < str_len; ++i, input += 2, cursor += 2) {
-    // Allow for the case where |buf == str|.
-    uint8_t temp = input[0];
-    cursor[0] = input[1];
-    cursor[1] = temp;
-  }
-  return buf;
-}
-#endif
-
-static uint16_t ReadUint16(const uint8_t*& buf) {
-  uint16_t x =
-      (static_cast<uint16_t>(buf[0])) | (static_cast<uint16_t>(buf[1]) << 8);
-  buf += sizeof(x);
-  return x;
-}
-
-static uint32_t ReadUint32(const uint8_t*& buf) {
-  uint32_t x = (static_cast<uint32_t>(buf[0])) |
-               (static_cast<uint32_t>(buf[1]) << 8) |
-               (static_cast<uint32_t>(buf[2]) << 16) |
-               (static_cast<uint32_t>(buf[3]) << 24);
-  buf += sizeof(x);
-  return x;
-}
-
-//-----------------------------------------------------------------------------
-
-// NTLM_Hash computes the NTLM hash of the given password.
-//
-// param password
-//       null-terminated unicode password.
-// param hash
-//       16-byte result buffer
-static void NTLM_Hash(const base::string16& password, uint8_t* hash) {
-#ifdef IS_BIG_ENDIAN
-  uint32_t len = password.length();
-  uint8_t* passbuf;
-
-  passbuf = static_cast<uint8_t*>(malloc(len * 2));
-  WriteUnicodeLE(passbuf, password.data(), len);
-  weak_crypto::MD4Sum(passbuf, len * 2, hash);
-
-  free(passbuf);
-#else
-  weak_crypto::MD4Sum(reinterpret_cast<const uint8_t*>(password.data()),
-                      password.length() * 2, hash);
-#endif
-}
-
-//-----------------------------------------------------------------------------
-
-// LM_Response generates the LM response given a 16-byte password hash and the
-// challenge from the Type-2 message.
-//
-// param hash
-//       16-byte password hash
-// param challenge
-//       8-byte challenge from Type-2 message
-// param response
-//       24-byte buffer to contain the LM response upon return
-static void LM_Response(const uint8_t* hash,
-                        const uint8_t* challenge,
-                        uint8_t* response) {
-  uint8_t keybytes[21], k1[8], k2[8], k3[8];
-
-  memcpy(keybytes, hash, 16);
-  memset(keybytes + 16, 0, 5);
-
-  DESMakeKey(keybytes, k1);
-  DESMakeKey(keybytes + 7, k2);
-  DESMakeKey(keybytes + 14, k3);
-
-  DESEncrypt(k1, challenge, response);
-  DESEncrypt(k2, challenge, response + 8);
-  DESEncrypt(k3, challenge, response + 16);
-}
-
-//-----------------------------------------------------------------------------
-
-// Returns OK or a network error code.
-static int GenerateType1Msg(void** out_buf, uint32_t* out_len) {
-  //
-  // Verify that buf_len is sufficient.
-  //
-  *out_len = NTLM_TYPE1_HEADER_LEN;
-  *out_buf = malloc(*out_len);
-  if (!*out_buf)
-    return ERR_OUT_OF_MEMORY;
-
-  //
-  // Write out type 1 message.
-  //
-  void* cursor = *out_buf;
-
-  // 0 : signature
-  cursor = WriteBytes(cursor, NTLM_SIGNATURE, sizeof(NTLM_SIGNATURE));
-
-  // 8 : marker
-  cursor = WriteBytes(cursor, NTLM_TYPE1_MARKER, sizeof(NTLM_TYPE1_MARKER));
-
-  // 12 : flags
-  cursor = WriteDWORD(cursor, NTLM_TYPE1_FLAGS);
-
-  //
-  // NOTE: It is common for the domain and workstation fields to be empty.
-  //       This is true of Win2k clients, and my guess is that there is
-  //       little utility to sending these strings before the charset has
-  //       been negotiated.  We follow suite -- anyways, it doesn't hurt
-  //       to save some bytes on the wire ;-)
-  //
-
-  // 16 : supplied domain security buffer (empty)
-  cursor = WriteSecBuf(cursor, 0, 0);
-
-  // 24 : supplied workstation security buffer (empty)
-  cursor = WriteSecBuf(cursor, 0, 0);
-
-  return OK;
-}
-
-struct Type2Msg {
-  uint32_t flags;        // NTLM_Xxx bitwise combination
-  uint8_t challenge[8];  // 8 byte challenge
-  const void* target;    // target string (type depends on flags)
-  uint32_t target_len;   // target length in bytes
-};
+namespace {
 
-// Returns OK or a network error code.
-// TODO(wtc): This function returns ERR_UNEXPECTED when the input message is
-// invalid.  We should return a better error code.
-static int ParseType2Msg(const void* in_buf, uint32_t in_len, Type2Msg* msg) {
-  // Make sure in_buf is long enough to contain a meaningful type2 msg.
-  //
-  // 0  NTLMSSP Signature
-  // 8  NTLM Message Type
-  // 12 Target Name
-  // 20 Flags
-  // 24 Challenge
-  // 32 end of header, start of optional data blocks
-  //
-  if (in_len < NTLM_TYPE2_HEADER_LEN)
-    return ERR_UNEXPECTED;
-
-  const uint8_t* cursor = (const uint8_t*)in_buf;
-
-  // verify NTLMSSP signature
-  if (memcmp(cursor, NTLM_SIGNATURE, sizeof(NTLM_SIGNATURE)) != 0)
-    return ERR_UNEXPECTED;
-  cursor += sizeof(NTLM_SIGNATURE);
-
-  // verify Type-2 marker
-  if (memcmp(cursor, NTLM_TYPE2_MARKER, sizeof(NTLM_TYPE2_MARKER)) != 0)
-    return ERR_UNEXPECTED;
-  cursor += sizeof(NTLM_TYPE2_MARKER);
-
-  // read target name security buffer
-  uint32_t target_len = ReadUint16(cursor);
-  ReadUint16(cursor);                    // discard next 16-bit value
-  uint32_t offset = ReadUint32(cursor);  // get offset from in_buf
-  msg->target_len = 0;
-  msg->target = NULL;
-
-  // Target length 0 is valid and indicates no target information.
-  if (target_len != 0) {
-    // Check the offset / length combo is in range of the input buffer,
-    // including integer overflow checking.
-    if (target_len <= in_len && in_len - offset >= target_len) {
-      msg->target_len = target_len;
-      msg->target = ((const uint8_t*)in_buf) + offset;
-    } else {
-      // Reject a message with a non-zero target length that
-      // would cause an overflow.
-      return ERR_UNEXPECTED;
-    }
-  }
-
-  // read flags
-  msg->flags = ReadUint32(cursor);
-
-  // read challenge
-  memcpy(msg->challenge, cursor, sizeof(msg->challenge));
-  cursor += sizeof(msg->challenge);
-
-  NTLM_LOG(("NTLM type 2 message:\n"));
-  LogBuf("target", (const uint8_t*)msg->target, msg->target_len);
-  LogBuf("flags", (const uint8_t*)&msg->flags, 4);
-  LogFlags(msg->flags);
-  LogBuf("challenge", msg->challenge, sizeof(msg->challenge));
-
-  // We currently do not implement LMv2/NTLMv2 or NTLM2 responses,
-  // so we can ignore target information.  We may want to enable
-  // support for these alternate mechanisms in the future.
-  return OK;
-}
-
-static void GenerateRandom(uint8_t* output, size_t n) {
-  for (size_t i = 0; i < n; ++i)
-    output[i] = base::RandInt(0, 255);
-}
-
-// Returns OK or a network error code.
-static int GenerateType3Msg(const base::string16& domain,
-                            const base::string16& username,
-                            const base::string16& password,
-                            const std::string& hostname,
-                            const void* rand_8_bytes,
-                            const void* in_buf,
-                            uint32_t in_len,
-                            void** out_buf,
-                            uint32_t* out_len) {
-  // in_buf contains Type-2 msg (the challenge) from server.
-
-  int rv;
-  Type2Msg msg;
-
-  rv = ParseType2Msg(in_buf, in_len, &msg);
-  if (rv != OK)
-    return rv;
-
-  bool unicode = (msg.flags & NTLM_NegotiateUnicode) != 0;
-
-// Temporary buffers for unicode strings
-#ifdef IS_BIG_ENDIAN
-  base::string16 ucs_domain_buf, ucs_user_buf;
-#endif
-  base::string16 ucs_host_buf;
-  // Temporary buffers for oem strings
-  std::string oem_domain_buf, oem_user_buf;
-  // Pointers and lengths for the string buffers; encoding is unicode if
-  // the "negotiate unicode" flag was set in the Type-2 message.
-  const void* domain_ptr;
-  const void* user_ptr;
-  const void* host_ptr;
-  uint32_t domain_len, user_len, host_len;
-
-  //
-  // Get domain name.
-  //
-  if (unicode) {
-#ifdef IS_BIG_ENDIAN
-    ucs_domain_buf = domain;
-    domain_ptr = ucs_domain_buf.data();
-    domain_len = ucs_domain_buf.length() * 2;
-    WriteUnicodeLE(const_cast<void*>(domain_ptr),
-                   (const base::char16*)domain_ptr, ucs_domain_buf.length());
-#else
-    domain_ptr = domain.data();
-    domain_len = domain.length() * 2;
-#endif
-  } else {
-    oem_domain_buf = base::SysWideToNativeMB(base::UTF16ToWide(domain));
-    domain_ptr = oem_domain_buf.data();
-    domain_len = oem_domain_buf.length();
-  }
-
-  //
-  // Get user name.
-  //
-  if (unicode) {
-#ifdef IS_BIG_ENDIAN
-    ucs_user_buf = username;
-    user_ptr = ucs_user_buf.data();
-    user_len = ucs_user_buf.length() * 2;
-    WriteUnicodeLE(const_cast<void*>(user_ptr), (const base::char16*)user_ptr,
-                   ucs_user_buf.length());
-#else
-    user_ptr = username.data();
-    user_len = username.length() * 2;
-#endif
-  } else {
-    oem_user_buf = base::SysWideToNativeMB(base::UTF16ToWide(username));
-    user_ptr = oem_user_buf.data();
-    user_len = oem_user_buf.length();
-  }
-
-  //
-  // Get workstation name (use local machine's hostname).
-  //
-  if (unicode) {
-    // hostname is ASCII, so we can do a simple zero-pad expansion:
-    ucs_host_buf.assign(hostname.begin(), hostname.end());
-    host_ptr = ucs_host_buf.data();
-    host_len = ucs_host_buf.length() * 2;
-#ifdef IS_BIG_ENDIAN
-    WriteUnicodeLE(const_cast<void*>(host_ptr), (const base::char16*)host_ptr,
-                   ucs_host_buf.length());
-#endif
-  } else {
-    host_ptr = hostname.data();
-    host_len = hostname.length();
-  }
-
-  //
-  // Now that we have generated all of the strings, we can allocate out_buf.
-  //
-  *out_len = NTLM_TYPE3_HEADER_LEN + host_len + domain_len + user_len +
-             LM_RESP_LEN + NTLM_RESP_LEN;
-  *out_buf = malloc(*out_len);
-  if (!*out_buf)
-    return ERR_OUT_OF_MEMORY;
-
-  //
-  // Next, we compute the LM and NTLM responses.
-  //
-  uint8_t lm_resp[LM_RESP_LEN];
-  uint8_t ntlm_resp[NTLM_RESP_LEN];
-  uint8_t ntlm_hash[NTLM_HASH_LEN];
-
-  // compute NTLM2 session response
-  base::MD5Digest session_hash;
-  uint8_t temp[16];
-
-  memcpy(lm_resp, rand_8_bytes, 8);
-  memset(lm_resp + 8, 0, LM_RESP_LEN - 8);
-
-  memcpy(temp, msg.challenge, 8);
-  memcpy(temp + 8, lm_resp, 8);
-  base::MD5Sum(temp, 16, &session_hash);
-
-  NTLM_Hash(password, ntlm_hash);
-  LM_Response(ntlm_hash, session_hash.a, ntlm_resp);
-
-  //
-  // Finally, we assemble the Type-3 msg :-)
-  //
-  void* cursor = *out_buf;
-  uint32_t offset;
-
-  // 0 : signature
-  cursor = WriteBytes(cursor, NTLM_SIGNATURE, sizeof(NTLM_SIGNATURE));
-
-  // 8 : marker
-  cursor = WriteBytes(cursor, NTLM_TYPE3_MARKER, sizeof(NTLM_TYPE3_MARKER));
-
-  // 12 : LM response sec buf
-  offset = NTLM_TYPE3_HEADER_LEN + domain_len + user_len + host_len;
-  cursor = WriteSecBuf(cursor, LM_RESP_LEN, offset);
-  memcpy(static_cast<uint8_t*>(*out_buf) + offset, lm_resp, LM_RESP_LEN);
-
-  // 20 : NTLM response sec buf
-  offset += LM_RESP_LEN;
-  cursor = WriteSecBuf(cursor, NTLM_RESP_LEN, offset);
-  memcpy(static_cast<uint8_t*>(*out_buf) + offset, ntlm_resp, NTLM_RESP_LEN);
-
-  // 28 : domain name sec buf
-  offset = NTLM_TYPE3_HEADER_LEN;
-  cursor = WriteSecBuf(cursor, domain_len, offset);
-  memcpy(static_cast<uint8_t*>(*out_buf) + offset, domain_ptr, domain_len);
-
-  // 36 : user name sec buf
-  offset += domain_len;
-  cursor = WriteSecBuf(cursor, user_len, offset);
-  memcpy(static_cast<uint8_t*>(*out_buf) + offset, user_ptr, user_len);
-
-  // 44 : workstation (host) name sec buf
-  offset += user_len;
-  cursor = WriteSecBuf(cursor, host_len, offset);
-  memcpy(static_cast<uint8_t*>(*out_buf) + offset, host_ptr, host_len);
-
-  // 52 : session key sec buf (not used)
-  cursor = WriteSecBuf(cursor, 0, 0);
-
-  // 60 : negotiated flags
-  cursor = WriteDWORD(cursor, msg.flags & NTLM_TYPE1_FLAGS);
-
-  return OK;
+void GenerateRandom(uint8_t* output, size_t n) {
+  base::RandBytes(output, n);
 }
 
-// NTLM authentication is specified in "NTLM Over HTTP Protocol Specification"
-// [MS-NTHT].
+}  // namespace
 
 // static
 HttpAuthHandlerNTLM::GenerateRandomProc
@@ -581,7 +26,7 @@ HttpAuthHandlerNTLM::GenerateRandomProc
 HttpAuthHandlerNTLM::HostNameProc HttpAuthHandlerNTLM::get_host_name_proc_ =
     GetHostName;
 
-HttpAuthHandlerNTLM::HttpAuthHandlerNTLM() {}
+HttpAuthHandlerNTLM::HttpAuthHandlerNTLM() : ntlm_client_() {}
 
 bool HttpAuthHandlerNTLM::NeedsIdentity() {
   // This gets called for each round-trip.  Only require identity on
@@ -622,31 +67,23 @@ HttpAuthHandlerNTLM::Factory::Factory() {}
 
 HttpAuthHandlerNTLM::Factory::~Factory() {}
 
-int HttpAuthHandlerNTLM::GetNextToken(const void* in_token,
-                                      uint32_t in_token_len,
-                                      void** out_token,
-                                      uint32_t* out_token_len) {
-  int rv = 0;
-
-  // If in_token is non-null, then assume it contains a type 2 message...
-  if (in_token) {
-    LogToken("in-token", in_token, in_token_len);
+ntlm::Buffer HttpAuthHandlerNTLM::GetNextToken(const ntlm::Buffer& in_token) {
+  // If in_token is non-empty, then assume it contains a challenge message,
+  // and generate the Authenticate message in reply. Otherwise return the
+  // Negotiate message.
+  if (in_token.empty()) {
+    return ntlm_client_.GetNegotiateMessage();
+  } else {
     std::string hostname = get_host_name_proc_();
     if (hostname.empty())
-      return ERR_UNEXPECTED;
-    uint8_t rand_buf[8];
-    generate_random_proc_(rand_buf, 8);
-    rv = GenerateType3Msg(domain_, credentials_.username(),
-                          credentials_.password(), hostname, rand_buf, in_token,
-                          in_token_len, out_token, out_token_len);
-  } else {
-    rv = GenerateType1Msg(out_token, out_token_len);
-  }
-
-  if (rv == OK)
-    LogToken("out-token", *out_token, *out_token_len);
+      return ntlm::Buffer();
+    uint8_t client_challenge[8];
+    generate_random_proc_(client_challenge, 8);
 
-  return rv;
+    return ntlm_client_.GenerateAuthenticateMessage(
+        domain_, credentials_.username(), credentials_.password(), hostname,
+        client_challenge, in_token);
+  }
 }
 
 int HttpAuthHandlerNTLM::Factory::CreateAuthHandler(