Function challenge

modules/auth/challenge.c:161–255

* Create and send a challenge */

 * Create and send a challenge
 */
static inline int challenge(struct sip_msg* _msg, str *realm, qop_type_t _qop,
    int _code, const str *reason, const str_const *_challenge_msg, int algmask)
{
	struct hdr_field* h = NULL;
	auth_body_t* cred = 0;
	int i, ret, nalgs, index = 0;
	hdr_types_t hftype = 0; /* Makes gcc happy */
	struct sip_uri *uri;
	str auth_hfs[LAST_ALG_SPTD - FIRST_ALG_SPTD + 1];
	const str_const *alg_val;
	const struct digest_auth_calc *digest_calc;
	struct nonce_params calc_np;

	switch(_code) {
	case WWW_AUTH_CODE:
		get_authorized_cred(_msg->authorization, &h);
		hftype = HDR_AUTHORIZATION_T;
		break;
	case PROXY_AUTH_CODE:
		get_authorized_cred(_msg->proxy_auth, &h);
		hftype = HDR_PROXYAUTH_T;
		break;
	}

	if (h) cred = (auth_body_t*)(h->parsed);

	if (realm->len == 0) {
		if (get_realm(_msg, hftype, &uri) < 0) {
			LM_ERR("failed to extract URI\n");
			if (send_resp(_msg, 400, &str_init(MESSAGE_400), NULL, 0) == -1) {
				LM_ERR("failed to send the response\n");
				return -1;
			}
			return 0;
		}

		realm = &uri->host;
		strip_realm(realm);
	}

	nalgs = 0;
	if (algmask >= ALG_MD5SESS && _qop == QOP_UNSPEC_D) {
		/* RFC8760 algos and XYZ-sess mandates QOP */
		_qop = QOP_AUTH_D;
	}
	if(!disable_nonce_check) {
		/* get the nonce index and mark it as used */
		index= reserve_nonce_index();
		if(index == -1)
		{
			LM_ERR("no more nonces can be generated\n");
			return -1;
		}
		LM_DBG("nonce index= %d\n", index);
	}

	if (clock_gettime(CLOCK_REALTIME, &calc_np.expires) != 0) {
		LM_ERR("clock_gettime failed\n");