auth_client.c

Sofia SIP is an open-source SIP User-Agent library, compliant with the IETF RFC3261 specification.

    if (!ca->ca_user || !ca->ca_pass || !ca->ca_credential_class)
      return 0;
    if (AUTH_CLIENT_IS_EXTENDED(ca) && ca->ca_clear)
      return 0;
  }

  return 1;
}

/**Authorize a request.
 *
 * The function auc_authorization() is used to add correct authentication
 * headers to a request. The authentication headers will contain the
 * credentials generated by the list of authenticators.
 *
 * @param[in,out] auc_list  list of authenticators 
 * @param[out] msg          message to be authenticated
 * @param[out] pub          headers of the message
 * @param[in] method        request method
 * @param[in] url           request URI
 * @param[in] body          message body (NULL if empty)
 * 
 * @retval 1 when successful
 * @retval 0 when there is not enough credentials
 * @retval -1 upon an error
 */
int auc_authorization(auth_client_t **auc_list, msg_t *msg, msg_pub_t *pub,
		      char const *method, 
		      url_t const *url, 
		      msg_payload_t const *body)
{
  auth_client_t *ca;
  msg_mclass_t const *mc = msg_mclass(msg);

  if (auc_list == NULL || msg == NULL)
    return -1;

  if (!auc_has_authorization(auc_list))
    return 0;

  if (pub == NULL)
    pub = msg_object(msg);

  /* Remove existing credentials */
  for (ca = *auc_list; ca; ca = ca->ca_next) {
    msg_header_t **hh = msg_hclass_offset(mc, pub, ca->ca_credential_class);

    while (hh && *hh)
      msg_header_remove(msg, pub, *hh);
  }

  /* Insert new credentials */
  for (; *auc_list; auc_list = &(*auc_list)->ca_next) {
    su_home_t *home = msg_home(msg);
    msg_header_t *h = NULL;

    ca = *auc_list;

    if (!ca->ca_auc)
      continue;

    if (ca->ca_auc->auc_authorize(ca, home, method, url, body, &h) < 0)
      return -1;
    if (h == NULL)
      continue;
    if (msg_header_insert(msg, pub, h) < 0)
      return -1;
  }

  return 1;
}

/**Generate headers authorizing a request.
 *
 * The function auc_authorization_headers() is used to generate
 * authentication headers for a request. The list of authentication headers
 * will contain the credentials generated by the list of authenticators.
 *
 * @param[in] auc_list      list of authenticators 
 * @param[in] home          memory home used to allocate headers
 * @param[in] method        request method
 * @param[in] url           request URI
 * @param[in] body          message body (NULL if empty)
 * @param[out] return_headers  authorization headers return value
 * 
 * @retval 1 when successful
 * @retval 0 when there is not enough credentials
 * @retval -1 upon an error
 */
int auc_authorization_headers(auth_client_t **auc_list, 
			      su_home_t *home,
			      char const *method, 
			      url_t const *url, 
			      msg_payload_t const *body,
			      msg_header_t **return_headers)
{
  auth_client_t *ca;

  /* Make sure every challenge has credentials */
  if (!auc_has_authorization(auc_list))
    return 0;

  /* Create new credential headers */
  for (; *auc_list; auc_list = &(*auc_list)->ca_next) {
    msg_header_t *h = NULL;

    ca = *auc_list;

    if (!ca->ca_auc)
      continue;

    if (ca->ca_auc->auc_authorize(ca, home, method, url, body, &h) < 0)
      return -1;

    *return_headers = h;

    while (*return_headers)
      return_headers = &(*return_headers)->sh_next;
  }

  return 1;
}

/* ---------------------------------------------------------------------- */
/* Basic scheme */

static int auc_basic_authorization(auth_client_t *ca,
				   su_home_t *h,
				   char const *method, 
				   url_t const *url, 
				   msg_payload_t const *body,
				   msg_header_t **);

static const auth_client_plugin_t ca_basic_plugin = 
{ 
  /* auc_plugin_size: */ sizeof ca_basic_plugin,
  /* auc_size: */        sizeof (auth_client_t),
  /* auc_name: */       "Basic",
  /* auc_challenge: */   NULL,
  /* auc_authorize: */   auc_basic_authorization,
  /* auc_info: */        NULL,
  /* auc_clear: */       ca_clear_credentials
};

/**Create a basic authorization header.
 *
 * The function auc_basic_authorization() creates a basic authorization
 * header from username @a user and password @a pass. The authorization
 * header type is determined by @a hc - it can be sip_authorization_class,
 * sip_proxy_authorization_class, http_authorization_class, or
 * http_proxy_authorization_class, for instance.
 *
 * @param home memory home used to allocate memory for the new header
 * @param hc   header class for the header to be created
 * @param user user name
 * @param pass password
 * 
 * @return
 * The function auc_basic_authorization() returns a pointer to newly created 
 * authorization header, or NULL upon an error.
 */
int auc_basic_authorization(auth_client_t *ca, 
			    su_home_t *home,
			    char const *method, 
			    url_t const *url, 
			    msg_payload_t const *body,
			    msg_header_t **return_headers)
{
  msg_hclass_t *hc = ca->ca_credential_class;
  char const *user = ca->ca_user;
  char const *pass = ca->ca_pass;
  size_t ulen, plen, uplen, b64len, basiclen;
  char *basic, *base64, *userpass;
  char buffer[71];

  if (user == NULL || pass == NULL)
    return -1;

  if (AUTH_CLIENT_IS_EXTENDED(ca) && ca->ca_clear)
    return 0;

  ulen = strlen(user), plen = strlen(pass), uplen = ulen + 1 + plen;
  b64len = BASE64_SIZE(uplen);
  basiclen = strlen("Basic ") + b64len;

  if (sizeof(buffer) > basiclen + 1)
    basic = buffer;
  else
    basic = malloc(basiclen + 1);

  if (basic == NULL)
    return -1;

  /*
   * Basic authentication consists of username and password separated by
   * colon and then base64 encoded.
   */
  strcpy(basic, "Basic ");
  base64 = basic + strlen("Basic ");
  userpass = base64 + b64len - uplen;
  memcpy(userpass, user, ulen);
  userpass[ulen] = ':';
  memcpy(userpass + ulen + 1, pass, plen);
  userpass[uplen] = '\0';
  
  base64_e(base64, b64len + 1, userpass, uplen);

  base64[b64len] = '\0';

  *return_headers = msg_header_make(home, hc, basic);

  if (buffer != basic)
    free(basic);

  return *return_headers ? 0 : -1;
}

/* ---------------------------------------------------------------------- */
/* Digest scheme */

typedef struct auth_digest_client_s
{
  auth_client_t cda_client;

  int           cda_ncount;
  char const   *cda_cnonce;
  auth_challenge_t cda_ac[1];
} auth_digest_client_t;

static int auc_digest_challenge(auth_client_t *ca, 
				msg_auth_t const *ch);
static int auc_digest_authorization(auth_client_t *ca, 
				    su_home_t *h,
				    char const *method, 
				    url_t const *url, 
				    msg_payload_t const *body,
				    msg_header_t **);
static int auc_digest_info(auth_client_t *ca, 
			   msg_auth_info_t const *info);

static const auth_client_plugin_t ca_digest_plugin = 
{ 
  /* auc_plugin_size: */ sizeof ca_digest_plugin,
  /* auc_size: */        sizeof (auth_digest_client_t),
  /* auc_name: */       "Digest", 
  /* auc_challenge: */   auc_digest_challenge,
  /* auc_authorize: */   auc_digest_authorization,
  /* auc_info: */        auc_digest_info,
  /* auc_clear: */       ca_clear_credentials
};

/** Store a digest authorization challenge.
 *
 * @retval 2 if credentials need to be (re)sent
 * @retval 1 if challenge was updated
 * @retval -1 upon an error
 */
static int auc_digest_challenge(auth_client_t *ca, msg_auth_t const *ch)
{
  su_home_t *home = ca->ca_home;
  auth_digest_client_t *cda = (auth_digest_client_t *)ca;
  auth_challenge_t ac[1] = {{ sizeof ac }};
  int stale;

  if (auth_digest_challenge_get(home, ac, ch->au_params) < 0)
    goto error;

  /* Check that we can handle the challenge */
  if (!ac->ac_md5 && !ac->ac_md5sess)
    goto error;
  if (ac->ac_qop && !ac->ac_auth && !ac->ac_auth_int)
    goto error;

  stale = ac->ac_stale || cda->cda_ac->ac_nonce == NULL;

  if (ac->ac_qop && (cda->cda_cnonce == NULL || ac->ac_stale)) {
    su_guid_t guid[1];
    char *cnonce;
    size_t b64len = BASE64_MINSIZE(sizeof(guid)) + 1;
    if (cda->cda_cnonce != NULL)
      /* Free the old one if we are updating after stale=true */
      su_free(home, (void *)cda->cda_cnonce);
    su_guid_generate(guid);
    cda->cda_cnonce = cnonce = su_alloc(home, b64len);
    base64_e(cnonce, b64len, guid, sizeof(guid));
    cda->cda_ncount = 0;
  }

  auth_digest_challenge_free_params(home, cda->cda_ac);

  *cda->cda_ac = *ac;

  return stale ? 2 : 1;

 error:
  auth_digest_challenge_free_params(home, ac);
  return -1;
}

static int auc_digest_info(auth_client_t *ca,
			   msg_auth_info_t const *info)
{
  auth_digest_client_t *cda = (auth_digest_client_t *)ca;
  su_home_t *home = ca->ca_home;
  char const *nextnonce = NULL;
  issize_t n;

  n = auth_get_params(home, info->ai_params,
		      "nextnonce=", &nextnonce,
		      NULL);

  if (n <= 0)
    return n;

  cda->cda_ac->ac_nonce = nextnonce;

  return 1;
}

/**Create a digest authorization header.
 *
 * Creates a digest authorization header from username @a user and password
 * @a pass, client nonce @a cnonce, client nonce count @a nc, request method
 * @a method, request URI @a uri and message body @a data. The authorization
 * header type is determined by @a hc - it can be either
 * sip_authorization_class or sip_proxy_authorization_class, as well as
 * http_authorization_class or http_proxy_authorization_class.
 *
 * @retval 1 when authorization headers has been created  
 * @retval 0 when there is no credentials
 * @retval -1 upon an error
 */
static
int auc_digest_authorization(auth_client_t *ca, 
			     su_home_t *home,
			     char const *method, 
			     url_t const *url, 
			     msg_payload_t const *body,
			     msg_header_t **return_headers)
{
  auth_digest_client_t *cda = (auth_digest_client_t *)ca;
  msg_hclass_t *hc = ca->ca_credential_class;
  char const *user = ca->ca_user;
  char const *pass = ca->ca_pass;
  auth_challenge_t const *ac = cda->cda_ac;
  char const *cnonce = cda->cda_cnonce;
  unsigned nc = ++cda->cda_ncount;
  char *uri = url_as_string(home, url);
  void const *data = body ? body->pl_data : "";
  usize_t dlen = body ? body->pl_len : 0;

  msg_header_t *h;
  auth_hexmd5_t sessionkey, response;
  auth_response_t ar[1] = {{ 0 }};
  char ncount[17];

  if (!user || !pass || (AUTH_CLIENT_IS_EXTENDED(ca) && ca->ca_clear))
    return 0;

  ar->ar_size = sizeof(ar);
  ar->ar_username = user;
  ar->ar_realm = ac->ac_realm;
  ar->ar_nonce = ac->ac_nonce;
  ar->ar_algorithm = NULL;
  ar->ar_md5 = ac->ac_md5;
  ar->ar_md5sess = ac->ac_md5sess;
  ar->ar_opaque = ac->ac_opaque;
  ar->ar_qop = NULL;
  ar->ar_auth = ac->ac_auth;
  ar->ar_auth_int = ac->ac_auth_int;
  ar->ar_uri = uri;

  /* If there is no qop, we MUST NOT include cnonce or nc */
  if (!ar->ar_auth && !ar->ar_auth_int)
    cnonce = NULL;

  if (cnonce) {
    snprintf(ncount, sizeof(ncount), "%08x", nc);
    ar->ar_cnonce = cnonce;
    ar->ar_nc = ncount;
  }

  auth_digest_sessionkey(ar, sessionkey, pass);
  auth_digest_response(ar, response, sessionkey, method, data, dlen);

  h = msg_header_format(home, hc, 
			"Digest "
			"username=\"%s\", "
			"realm=\"%s\", "
			"nonce=\"%s"
			"%s%s"
			"%s%s"
			"%s%s, "
			"uri=\"%s\", "
			"response=\"%s\""
			"%s%s"
			"%s%s",
			ar->ar_username, 
			ar->ar_realm,
			ar->ar_nonce,
			cnonce ? "\",  cnonce=\"" : "", 
			cnonce ? cnonce : "",
			ar->ar_opaque ? "\",  opaque=\"" : "", 
			ar->ar_opaque ? ar->ar_opaque : "",
			ar->ar_algorithm ? "\", algorithm=" : "",
			ar->ar_algorithm ? ar->ar_algorithm : "",
			ar->ar_uri,
			response,
			ar->ar_auth || ar->ar_auth_int ? ", qop=" : "", 
			ar->ar_auth_int ? "auth-int" : 
			(ar->ar_auth ? "auth" : ""),
			cnonce ? ", nc=" : "", 
			cnonce ? ncount : "");

  su_free(home, uri);

  if (!h)
    return -1;
  *return_headers = h;
  return 0;
}


/* ---------------------------------------------------------------------- */

#define MAX_AUC 20

static auth_client_plugin_t const *ca_plugins[MAX_AUC] = 
{
  &ca_digest_plugin, &ca_basic_plugin, NULL
};

/** Register an authentication client plugin */
int auc_register_plugin(auth_client_plugin_t const *plugin)
{
  int i;

  if (plugin == NULL ||
      plugin->auc_name == NULL ||
      plugin->auc_authorize == NULL)
    return errno = EFAULT, -1;

  if (plugin->auc_size < (int) sizeof (auth_client_t))
    return errno = EINVAL, -1;

  for (i = 0; i < MAX_AUC; i++) {
    if (ca_plugins[i] == NULL || 
	strcmp(plugin->auc_name, ca_plugins[i]->auc_name) == 0) {
      ca_plugins[i] = plugin;
      return 0;
    }
  }

  return errno = ENOMEM, -1;
}

/** Allocate an (possibly extended) auth_client_t structure. */
static
auth_client_t *ca_create(su_home_t *home,
			 char const *scheme,
			 char const *realm)
{
  auth_client_plugin_t const *auc = NULL;
  auth_client_t *ca;
  size_t aucsize = (sizeof *ca), realmlen, size;
  char *s;
  int i;

  if (scheme == NULL || realm == NULL)
    return (void)(errno = EFAULT), NULL;

  realmlen = strlen(realm) + 1;

  for (i = 0; i < MAX_AUC; i++) {
    auc = ca_plugins[i];
    if (!auc || strcasecmp(auc->auc_name, scheme) == 0)
      break;
  }

  /* XXX - should report error if the auth scheme is not known? */

  aucsize = auc ? (size_t)auc->auc_size : (sizeof *ca);
  size = aucsize + realmlen;
  if (!auc)
    size += strlen(scheme) + 1;

  ca = su_home_clone(home, (isize_t)size);
  if (!ca)
    return ca;

  s = (char *)ca + aucsize;
  ca->ca_auc = auc;
  ca->ca_realm = strcpy(s, realm);
  ca->ca_scheme = auc ? auc->auc_name : strcpy(s + realmlen, scheme);

  return ca;
}

void ca_destroy(su_home_t *home, auth_client_t *ca)
{
  su_free(home, ca);
}


#if HAVE_SOFIA_SIP
#include <sofia-sip/sip.h>

/**Authorize a SIP request.
 *
 * The function auc_authorize() is used to add correct authentication
 * headers to a SIP request. The authentication headers will contain the
 * credentials generated by the list of authenticators.
 *
 * @param[in,out] auc_list  list of authenticators 
 * @param[in,out] msg       message to be authenticated
 * @param[in,out] sip       sip headers of the message
 * 
 * @retval 1 when successful
 * @retval 0 when there is not enough credentials
 * @retval -1 upon an error
 */
int auc_authorize(auth_client_t **auc_list, msg_t *msg, sip_t *sip)
{
  sip_request_t *rq = sip ? sip->sip_request : NULL;

  if (!rq)
    return 0;

  return auc_authorization(auc_list, msg, (msg_pub_t *)sip, 
			   rq->rq_method_name, 
			   /*
			     RFC 3261 defines the protection domain based
			     only on realm, so we do not bother get a
			     correct URI to auth module.
			   */
			   rq->rq_url, 
			   sip->sip_payload);
}
#endif