plugin/httpda.c

/*

httpda.c

gSOAP HTTP Digest Authentication plugin.
Supports both Basic and Digest authentication.

Usage (client side, see httpdatest.h/.c for example):
soap_register_plugin(&soap, http_da);
if (soap_call_ns__method(&soap, ...) != SOAP_OK)
{ if (soap.error == 401) // HTTP authentication is required
  { if (!strcmp(soap.authrealm, authrealm)) // check authentication realm
    { struct http_da_info info; // to store userid and passwd
      http_da_save(&soap, &info, authrealm, userid, passwd);
      if (soap_call_ns__method(&soap, ...) == SOAP_OK)
      { ...
        soap_end(&soap);
	... // userid and passwd were deallocated
        http_da_restore(&soap, &info); // get userid and passwd after soap_end()
        if (!soap_call_ns__method(&soap, ...) == SOAP_OK)
	  ...
        http_da_release(&soap, &info); // remove userid and passwd

Usage (server side, see httpdatest.h/.c for example):
soap_register_plugin(&soap, http_da);
...
soap_serve(&soap);
...
int ns__method(struct soap *soap, ...)
{ if (soap->userid && soap->passwd) // Basic authentication
  { if (!strcmp(soap->userid, userid) && !strcmp(soap->passwd, passwd))
    { ... // can also check soap->authrealm 
      return SOAP_OK;
    }
  }
  else if (soap->authrealm && soap->userid) // Digest authentication
  { passwd = ... // database lookup on userid and authrealm to find passwd
    if (!strcmp(soap->authrealm, authrealm) && !strcmp(soap->userid, userid))
    { if (!http_da_verify_post(soap, passwd)) // HTTP POST DA verification
      { ...
        return SOAP_OK;
      }
    }
  }
  soap->authrealm = authrealm; // realm to send to client
  return 401; // Not authorized, challenge with digest authentication
}

Compile with -DWITH_OPENSSL
Link with OpenSSL (for md5evp.c), httpda.c, md5evp.c, and threads.c

gSOAP XML Web services tools
Copyright (C) 2000-2005, Robert van Engelen, Genivia Inc., All Rights Reserved.
This part of the software is released under one of the following licenses:
GPL, the gSOAP public license, or Genivia's license for commercial use.
--------------------------------------------------------------------------------
gSOAP public license.

The contents of this file are subject to the gSOAP Public License Version 1.3
(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.cs.fsu.edu/~engelen/soaplicense.html
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 Initial Developer of the Original Code is Robert A. van Engelen.
Copyright (C) 2000-2005, Robert van Engelen, Genivia, Inc., All Rights Reserved.
--------------------------------------------------------------------------------
GPL license.

This program is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free Software
Foundation; either version 2 of the License, or (at your option) any later
version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with
this program; if not, write to the Free Software Foundation, Inc., 59 Temple
Place, Suite 330, Boston, MA 02111-1307 USA

Author contact information:
engelen@genivia.com / engelen@acm.org
--------------------------------------------------------------------------------
A commercial use license is available from Genivia, Inc., contact@genivia.com
--------------------------------------------------------------------------------
*/

#include "httpda.h"

const char http_da_id[12] = HTTP_DA_ID;

/* session database and lock */
static struct http_da_session *http_da_session = NULL;
static MUTEX_TYPE http_da_session_lock;

#define HTTP_DA_NONCELEN 21
#define HTTP_DA_OPAQUELEN 9

/******************************************************************************\
 *
 *	Forward decls
 *
\******************************************************************************/

static int http_da_init(struct soap *soap, struct http_da_data *data);
static int http_da_copy(struct soap *soap, struct soap_plugin *dst, struct soap_plugin *src);
static void http_da_delete(struct soap *soap, struct soap_plugin *p);

static int http_da_post_header(struct soap *soap, const char *key, const char *val);
static int http_da_parse_header(struct soap *soap, const char *key, const char *val);
static int http_da_prepareinit(struct soap *soap);
static int http_da_preparesend(struct soap *soap, const char *buf, size_t len);
static int http_da_preparerecv(struct soap *soap, const char *buf, size_t len);
static int http_da_disconnect(struct soap *soap);

static int http_da_verify_method(struct soap *soap, char *method, char *passwd);
static void http_da_session_start(const char *realm, const char *nonce, const char *opaque);
static int http_da_session_update(const char *realm, const char *nonce, const char *opaque, const char *cnonce, const char *ncount);
static void http_da_session_cleanup();

void http_da_calc_nonce(struct soap *soap, char nonce[HTTP_DA_NONCELEN]);
void http_da_calc_opaque(struct soap *soap, char opaque[HTTP_DA_OPAQUELEN]);
static void http_da_calc_HA1(struct soap *soap, void **context, char *alg, char *userid, char *realm, char *passwd, char *nonce, char *cnonce, char HA1hex[33]);
static void http_da_calc_response(struct soap *soap, void **context, char HA1hex[33], char *nonce, char *ncount, char *cnonce, char *qop, char *method, char *uri, char entityHAhex[33], char response[33]);

/******************************************************************************\
 *
 *	Plugin registry
 *
\******************************************************************************/

int http_da(struct soap *soap, struct soap_plugin *p, void *arg)
{
  p->id = http_da_id;
  p->data = (void*)SOAP_MALLOC(soap, sizeof(struct http_da_data));
  p->fcopy = http_da_copy;
  p->fdelete = http_da_delete;
  if (p->data)
  {
    if (http_da_init(soap, (struct http_da_data*)p->data))
    {
      SOAP_FREE(soap, p->data);
      return SOAP_EOM;
    }
  }
  return SOAP_OK;
}

static int http_da_init(struct soap *soap, struct http_da_data *data)
{
  data->fposthdr = soap->fposthdr;
  soap->fposthdr = http_da_post_header;
  data->fparsehdr = soap->fparsehdr;
  soap->fparsehdr = http_da_parse_header;
  data->fprepareinit = soap->fprepareinit;
  soap->fprepareinit = http_da_prepareinit;
  data->context = NULL;
  memset(data->digest, 0, sizeof(data->digest));

  return SOAP_OK;
}

static int http_da_copy(struct soap *soap, struct soap_plugin *dst, struct soap_plugin *src)
{
  *dst = *src;
  dst->data = (void*)SOAP_MALLOC(soap, sizeof(struct http_da_data));
  memcpy(dst->data, src->data, sizeof(struct http_da_data));
  ((struct http_da_data*)dst->data)->context = NULL;
  memset(((struct http_da_data*)dst->data)->digest, 0, sizeof(((struct http_da_data*)dst->data)->digest));
  ((struct http_da_data*)dst->data)->nonce = NULL;
  ((struct http_da_data*)dst->data)->opaque = NULL;
  ((struct http_da_data*)dst->data)->qop = NULL;
  ((struct http_da_data*)dst->data)->alg = NULL;
  ((struct http_da_data*)dst->data)->nc = 0;
  ((struct http_da_data*)dst->data)->ncount = NULL;
  ((struct http_da_data*)dst->data)->cnonce = NULL;
  ((struct http_da_data*)dst->data)->response = NULL;
  return SOAP_OK;
}

static void http_da_delete(struct soap *soap, struct soap_plugin *p)
{
  struct http_da_data *data = (struct http_da_data*)soap_lookup_plugin(soap, http_da_id);
  if (data)
  {
    if (data->context)
      md5_handler(soap, &data->context, MD5_DELETE, NULL, 0);
    SOAP_FREE(soap, data);
  }
}

/******************************************************************************\
 *
 *	Callbacks
 *
\******************************************************************************/

static int http_da_post_header(struct soap *soap, const char *key, const char *val)
{
  struct http_da_data *data = (struct http_da_data*)soap_lookup_plugin(soap, http_da_id);

  if (!data)
    return SOAP_PLUGIN_ERROR;

  /* client's HTTP Authorization response */
  if (key && !strcmp(key, "Authorization"))
  {
    char HA1[33], entityHAhex[33], response[33];
    char cnonce[HTTP_DA_NONCELEN];
    char ncount[9];
    char *qop, *method;

    md5_handler(soap, &data->context, MD5_FINAL, data->digest, 0);

    http_da_calc_nonce(soap, cnonce);
    http_da_calc_HA1(soap, &data->context, data->alg, soap->userid, soap->authrealm, soap->passwd, data->nonce, cnonce, HA1);

    if (data->qop && !soap_tag_cmp(data->qop, "*auth-int*"))
    {
      qop = "auth-int";
      soap_s2hex(soap, data->digest, entityHAhex, 16);
    }
    else if (data->qop)
      qop = "auth";
    else
      qop = NULL;

    if (soap->status == SOAP_GET)
      method = "GET";
    else
      method = "POST";

    sprintf(ncount, "%8.8lx", data->nc++);

    http_da_calc_response(soap, &data->context, HA1, data->nonce, ncount, cnonce, qop, method, soap->path, entityHAhex, response);

    if (qop)
      sprintf(soap->tmpbuf, "Digest realm=\"%s\", username=\"%s\", nonce=\"%s\", uri=\"%s\", qop=\"%s\", nc=%s, cnonce=\"%s\", response=\"%s\", opaque=\"%s\"", soap->authrealm, soap->userid, data->nonce, soap->path, qop, ncount, cnonce, response, data->opaque);
    else
      sprintf(soap->tmpbuf, "Digest realm=\"%s\", username=\"%s\", nonce=\"%s\", uri=\"%s\", response=\"%s\", opaque=\"%s\"", soap->authrealm, soap->userid, data->nonce, soap->path, response, data->opaque);

    return data->fposthdr(soap, key, soap->tmpbuf);
  }

  /* server's HTTP Authorization response */
  if (key && !strcmp(key, "WWW-Authenticate"))
  {
    char nonce[HTTP_DA_NONCELEN];
    char opaque[HTTP_DA_OPAQUELEN];

    http_da_calc_nonce(soap, nonce);
    http_da_calc_opaque(soap, opaque);

    http_da_session_start(soap->authrealm, nonce, opaque);

    sprintf(soap->tmpbuf, "Digest realm=\"%s\", qop=\"auth,auth-int\", nonce=\"%s\", opaque=\"%s\"", soap->authrealm, nonce, opaque);

    return data->fposthdr(soap, key, soap->tmpbuf);
  }

  return data->fposthdr(soap, key, val);
}

static int http_da_parse_header(struct soap *soap, const char *key, const char *val)
{
  struct http_da_data *data = (struct http_da_data*)soap_lookup_plugin(soap, http_da_id);

  if (!data)
    return SOAP_PLUGIN_ERROR;

  /* check if server received Authorization Digest HTTP header from client */
  if (!soap_tag_cmp(key, "Authorization") && !soap_tag_cmp(val, "Digest *"))
  {
    soap->authrealm = soap_strdup(soap, soap_get_header_attribute(soap, val + 7, "realm"));
    soap->userid = soap_strdup(soap, soap_get_header_attribute(soap, val + 7, "username"));
    soap->passwd = NULL;
    data->nonce = soap_strdup(soap, soap_get_header_attribute(soap, val + 7, "nonce"));
    data->opaque = soap_strdup(soap, soap_get_header_attribute(soap, val + 7, "opaque"));
    data->qop = soap_strdup(soap, soap_get_header_attribute(soap, val + 7, "qop"));
    data->alg = NULL;
    data->ncount = soap_strdup(soap, soap_get_header_attribute(soap, val + 7, "nc"));
    data->cnonce = soap_strdup(soap, soap_get_header_attribute(soap, val + 7, "cnonce"));
    data->response = soap_strdup(soap, soap_get_header_attribute(soap, val + 7, "response"));
    if (data->qop && !soap_tag_cmp(data->qop, "auth-int"))
    {
      if (soap->fpreparerecv != http_da_preparerecv)
      {
        data->fpreparerecv = soap->fpreparerecv;
        soap->fpreparerecv = http_da_preparerecv;
      }
      if (soap->fdisconnect != http_da_disconnect)
      {
        data->fdisconnect = soap->fdisconnect;
        soap->fdisconnect = http_da_disconnect;
      }
      md5_handler(soap, &data->context, MD5_INIT, NULL, 0);
    }
    return SOAP_OK;
  }

  /* check if client received WWW-Authenticate Digest HTTP header from server */
  if (!soap_tag_cmp(key, "WWW-Authenticate") && !soap_tag_cmp(val, "Digest *"))
  {
    soap->authrealm = soap_strdup(soap, soap_get_header_attribute(soap, val + 7, "realm"));
    data->nonce = soap_strdup(soap, soap_get_header_attribute(soap, val + 7, "nonce"));
    data->opaque = soap_strdup(soap, soap_get_header_attribute(soap, val + 7, "opaque"));
    data->qop = soap_strdup(soap, soap_get_header_attribute(soap, val + 7, "qop"));
    data->alg = soap_strdup(soap, soap_get_header_attribute(soap, val + 7, "algorithm"));
    data->nc = 1;
    data->ncount = NULL;
    data->cnonce = NULL;
    data->response = NULL;
    return SOAP_OK;
  }

  return data->fparsehdr(soap, key, val);
}

static int http_da_prepareinit(struct soap *soap)
{
  struct http_da_data *data = (struct http_da_data*)soap_lookup_plugin(soap, http_da_id);

  if (!data)
    return SOAP_PLUGIN_ERROR;

  if ((soap->mode & SOAP_IO) != SOAP_IO_STORE && (soap->mode & (SOAP_ENC_DIME | SOAP_ENC_MIME)))
  { /* TODO: handle attachments automatically, does not work yet */
    soap->mode &= ~SOAP_IO;
    soap->mode |= SOAP_IO_STORE;
  }
  else
  {
    if (soap->fpreparerecv == http_da_preparerecv)
      soap->fpreparerecv = data->fpreparerecv;
    if (soap->fdisconnect == http_da_disconnect)
      soap->fdisconnect = data->fdisconnect;

    if (soap->userid && soap->passwd)
    {
      md5_handler(soap, &data->context, MD5_INIT, NULL, 0);
      if (soap->fpreparesend != http_da_preparesend)
      {
        data->fpreparesend = soap->fpreparesend;
        soap->fpreparesend = http_da_preparesend;
      }
    }

    if (data->fprepareinit)
      return data->fprepareinit(soap);
  }

  return SOAP_OK;
}

static int http_da_preparesend(struct soap *soap, const char *buf, size_t len)
{
  struct http_da_data *data = (struct http_da_data*)soap_lookup_plugin(soap, http_da_id);

  if (!data)
    return SOAP_PLUGIN_ERROR;

  md5_handler(soap, &data->context, MD5_UPDATE, (char*)buf, len);

  if (data->fpreparesend)
    return data->fpreparesend(soap, buf, len);

  return SOAP_OK;
}

static int http_da_preparerecv(struct soap *soap, const char *buf, size_t len)
{
  struct http_da_data *data = (struct http_da_data*)soap_lookup_plugin(soap, http_da_id);

  if (!data)
    return SOAP_PLUGIN_ERROR;

  md5_handler(soap, &data->context, MD5_UPDATE, (char*)buf, len);

  if (data->fpreparerecv)
    return data->fpreparerecv(soap, buf, len);

  return SOAP_OK;
}

static int http_da_disconnect(struct soap *soap)
{
  struct http_da_data *data = (struct http_da_data*)soap_lookup_plugin(soap, http_da_id);

  if (!data)
    return SOAP_PLUGIN_ERROR;

  md5_handler(soap, &data->context, MD5_FINAL, data->digest, 0);

  soap->fpreparerecv = data->fpreparerecv;
  soap->fdisconnect = data->fdisconnect;

  if (soap->fdisconnect)
    return soap->fdisconnect(soap);

  return SOAP_OK;
}

/******************************************************************************\
 *
 *	Client-side digest authentication state management
 *
\******************************************************************************/

void http_da_save(struct soap *soap, struct http_da_info *info, const char *realm, const char *userid, const char *passwd)
{
  struct http_da_data *data = (struct http_da_data*)soap_lookup_plugin(soap, http_da_id);
  if (!data)
    return;
  info->authrealm = soap->authrealm = soap_strdup(NULL, realm);
  info->userid = soap->userid = soap_strdup(NULL, userid);
  info->passwd = soap->passwd = soap_strdup(NULL, passwd);
  info->nonce = soap_strdup(NULL, data->nonce);
  info->opaque = soap_strdup(NULL, data->opaque);
  info->qop = soap_strdup(NULL, data->qop);
  info->alg = soap_strdup(NULL, data->alg);
}

void http_da_restore(struct soap *soap, struct http_da_info *info)
{
  struct http_da_data *data = (struct http_da_data*)soap_lookup_plugin(soap, http_da_id);
  if (!data)
    return;
  soap->authrealm = info->authrealm;
  soap->userid = info->userid;
  soap->passwd = info->passwd;
  data->nonce = info->nonce;
  data->opaque = info->opaque;
  data->qop = info->qop;
  data->alg = info->alg;
}

void http_da_release(struct soap *soap, struct http_da_info *info)
{
  struct http_da_data *data = (struct http_da_data*)soap_lookup_plugin(soap, http_da_id);
  if (!data)
    return;

  soap->authrealm = NULL;
  soap->userid = NULL;
  soap->passwd = NULL;
  data->nonce = NULL;
  data->opaque = NULL;
  data->qop = NULL;
  data->alg = NULL;

  if (info->authrealm)
  {
    free(info->authrealm);
    info->authrealm = NULL;
  }
  if (info->userid)
  {
    free(info->userid);
    info->userid = NULL;
  }
  if (info->passwd)
  {
    free(info->passwd);
    info->passwd = NULL;
  }
  if (info->nonce)
  {
    free(info->nonce);
    info->nonce = NULL;
  }
  if (info->opaque)
  {
    free(info->opaque);
    info->opaque = NULL;
  }
  if (info->qop)
  {
    free(info->qop);
    info->qop = NULL;
  }
  if (info->alg)
  {
    free(info->alg);
    info->alg = NULL;
  }
}

/******************************************************************************\
 *
 *	Server-side digest authentication verification
 *
\******************************************************************************/

int http_da_verify_post(struct soap *soap, char *passwd)
{
  return http_da_verify_method(soap, "POST", passwd);
}

int http_da_verify_get(struct soap *soap, char *passwd)
{
  return http_da_verify_method(soap, "GET", passwd);
}

static int http_da_verify_method(struct soap *soap, char *method, char *passwd)
{
  struct http_da_data *data = (struct http_da_data*)soap_lookup_plugin(soap, http_da_id);
  char HA1[33], entityHAhex[33], response[33];

  if (!data)
    return SOAP_ERR;

  /* reject if none or basic authentication was used */
  if (!soap->authrealm
   || !soap->userid
   || soap->passwd)	/* passwd is set when basic auth is used */
    return SOAP_ERR;

  /* require at least qop="auth" to prevent replay attacks */
  if (!data->qop)
    return SOAP_ERR;

  if (http_da_session_update(soap->authrealm, data->nonce, data->opaque, data->cnonce, data->ncount))
    return SOAP_ERR;

  http_da_calc_HA1(soap, &data->context, NULL, soap->userid, soap->authrealm, passwd, data->nonce, data->cnonce, HA1);

  if (!soap_tag_cmp(data->qop, "auth-int"))
    soap_s2hex(soap, data->digest, entityHAhex, 16);

  http_da_calc_response(soap, &data->context, HA1, data->nonce, data->ncount, data->cnonce, data->qop, method, soap->path, entityHAhex, response);

#ifdef DEBUG
  fprintf(stderr, "Verifying client response=%s with calculated digest=%s\n", data->response, response);
#endif

  /* check digest response values */
  if (strcmp(data->response, response))
    return SOAP_ERR;

  return SOAP_OK;
}

/******************************************************************************\
 *
 *	Digest authentication session database management
 *
\******************************************************************************/

static void http_da_session_start(const char *realm, const char *nonce, const char *opaque)
{
  struct http_da_session *session;
  time_t now = time(NULL);

  if (now % 10 == 0) /* don't do this all the time to improve efficiency */
    http_da_session_cleanup();

#ifdef DEBUG
  fprintf(stderr, "Starting session realm=%s nonce=%s\n", realm, nonce);
#endif

  MUTEX_LOCK(http_da_session_lock);

  session = (struct http_da_session*)malloc(sizeof(struct http_da_session));
  if (session)
  {
    session->next = http_da_session;
    session->modified = now;
    session->realm = soap_strdup(NULL, realm);
    session->nonce = soap_strdup(NULL, nonce);
    session->opaque = soap_strdup(NULL, opaque);
    session->nc = 0;
    http_da_session = session;
  }

  MUTEX_UNLOCK(http_da_session_lock);
}

static int http_da_session_update(const char *realm, const char *nonce, const char *opaque, const char *cnonce, const char *ncount)
{
  struct http_da_session *session;

  if (!realm || !nonce || !opaque || !cnonce || !ncount)
    return SOAP_ERR;

#ifdef DEBUG
  fprintf(stderr, "Updating session realm=%s nonce=%s\n", realm, nonce);
#endif

  MUTEX_LOCK(http_da_session_lock);

  for (session = http_da_session; session; session = session->next)
    if (!strcmp(session->realm, realm) && !strcmp(session->nonce, nonce) && !strcmp(session->opaque, opaque))
      break;

  if (session)
  {
    unsigned long nc = soap_strtoul(ncount, NULL, 16);

    if (session->nc >= nc)
    {
      session->modified = 0; /* replay attack: terminate session */
      session = NULL;
    }
    else
    {
      session->nc = nc;
      session->modified = time(NULL);
    }
  }

  MUTEX_UNLOCK(http_da_session_lock);

  if (!session)
    return SOAP_ERR;

  return SOAP_OK;
}

static void http_da_session_cleanup()
{
  struct http_da_session **session;
  time_t now = time(NULL);

  MUTEX_LOCK(http_da_session_lock);

  session = &http_da_session;
  while (*session)
  {
    if ((*session)->modified + HTTP_DA_SESSION_TIMEOUT < now)
    {
      struct http_da_session *p = *session;

#ifdef DEBUG
      fprintf(stderr, "Deleting session realm=%s nonce=%s\n", p->realm, p->nonce);
#endif

      if (p->realm)
        free(p->realm);
      if (p->nonce)
        free(p->nonce);
      if (p->opaque)
        free(p->opaque);

      *session = p->next;
      free(p);
    }
    else
      session = &(*session)->next;
  }

  MUTEX_UNLOCK(http_da_session_lock);
}

/******************************************************************************\
 *
 *	Calculate hex nonce and opaque values
 *
\******************************************************************************/

void http_da_calc_nonce(struct soap *soap, char nonce[HTTP_DA_NONCELEN])
{
  static short count = 0xCA53;
  sprintf(nonce, "%8.8x%4.4hx%8.8x", (int)time(NULL), count++, soap_random);
}

void http_da_calc_opaque(struct soap *soap, char opaque[HTTP_DA_OPAQUELEN])
{
  sprintf(opaque, "%8.8x", soap_random);
}

/******************************************************************************\
 *
 *	Calculate HA1, HA2, and response digest as per RFC 2617 specification
 *
\******************************************************************************/

static void http_da_calc_HA1(struct soap *soap, void **context, char *alg, char *userid, char *realm, char *passwd, char *nonce, char *cnonce, char HA1hex[33])
{
  char HA1[16];

  md5_handler(soap, context, MD5_INIT, NULL, 0);
  md5_handler(soap, context, MD5_UPDATE, userid, strlen(userid));
  md5_handler(soap, context, MD5_UPDATE, ":", 1);
  md5_handler(soap, context, MD5_UPDATE, realm, strlen(realm));
  md5_handler(soap, context, MD5_UPDATE, ":", 1);
  md5_handler(soap, context, MD5_UPDATE, passwd, strlen(passwd));
  md5_handler(soap, context, MD5_FINAL, HA1, 0);

  if (alg && !soap_tag_cmp(alg, "MD5-sess"))
  {
    md5_handler(soap, context, MD5_INIT, NULL, 0);
    md5_handler(soap, context, MD5_UPDATE, HA1, 16);
    md5_handler(soap, context, MD5_UPDATE, ":", 1);
    md5_handler(soap, context, MD5_UPDATE, nonce, strlen(nonce));
    md5_handler(soap, context, MD5_UPDATE, ":", 1);
    md5_handler(soap, context, MD5_UPDATE, cnonce, strlen(cnonce));
    md5_handler(soap, context, MD5_FINAL, HA1, 0);
  };

  soap_s2hex(soap, HA1, HA1hex, 16);
};

static void http_da_calc_response(struct soap *soap, void **context, char HA1hex[33], char *nonce, char *ncount, char *cnonce, char *qop, char *method, char *uri, char entityHAhex[33], char response[33])
{
  char HA2[16], HA2hex[33], responseHA[16];

  md5_handler(soap, context, MD5_INIT, NULL, 0);
  md5_handler(soap, context, MD5_UPDATE, method, strlen(method));
  md5_handler(soap, context, MD5_UPDATE, ":", 1);
  md5_handler(soap, context, MD5_UPDATE, uri, strlen(uri));
  if (!soap_tag_cmp(qop, "auth-int"))
  { 
    md5_handler(soap, context, MD5_UPDATE, ":", 1);
    md5_handler(soap, context, MD5_UPDATE, entityHAhex, 32);
  }
  md5_handler(soap, context, MD5_FINAL, HA2, 0);

  soap_s2hex(soap, HA2, HA2hex, 16);

  md5_handler(soap, context, MD5_INIT, NULL, 0);
  md5_handler(soap, context, MD5_UPDATE, HA1hex, 32);
  md5_handler(soap, context, MD5_UPDATE, ":", 1);
  md5_handler(soap, context, MD5_UPDATE, nonce, strlen(nonce));
  md5_handler(soap, context, MD5_UPDATE, ":", 1);
  if (qop && *qop)
  {
    md5_handler(soap, context, MD5_UPDATE, ncount, strlen(ncount));
    md5_handler(soap, context, MD5_UPDATE, ":", 1);
    md5_handler(soap, context, MD5_UPDATE, cnonce, strlen(cnonce));
    md5_handler(soap, context, MD5_UPDATE, ":", 1);
    md5_handler(soap, context, MD5_UPDATE, qop, strlen(qop));
    md5_handler(soap, context, MD5_UPDATE, ":", 1);
  }
  md5_handler(soap, context, MD5_UPDATE, HA2hex, 32);
  md5_handler(soap, context, MD5_FINAL, responseHA, 0);

  soap_s2hex(soap, responseHA, response, 16);
}