rem: if (parse_headers(_m, HDR_FROM | HDR_EVENT | HDR_EXPIRES | HDR_ACCEPT, 0) == -1) {
add: if ( (parse_headers(_m, HDR_FROM | HDR_EVENT | HDR_EXPIRES | HDR_ACCEPT, 0) == -1) || (_m->from==0)||(_m->event==0)||(_m->expires==0) || (_m->accept==0) ) {
context: static int parse_hfs(struct sip_msg* _m, int accept_header_required){	if (parse_headers(_m, HDR_FROM | HDR_EVENT | HDR_EXPIRES | HDR_ACCEPT, 0) == -1) {		paerrno = PA_PARSE_ERR;		LOG(L_ERR, "parse_hfs(): Error while parsing headers\n");		return -1;	}	if (parse_from_header(_m) < 0) {		paerrno = PA_FROM_ERR;		LOG(L_ERR, "parse_hfs(): From malformed or missing\n");		return -6;	}	if (_m->event) {		if (parse_event(_m->event) < 0) {			paerrno = PA_EVENT_PARSE;			LOG(L_ERR, "parse_hfs(): Error while parsing Event header field\n");			return -8;		}	}	if (_m->expires) {		if (parse_expires(_m->expires) < 0) {			paerrno = PA_EXPIRES_PARSE;			LOG(L_ERR, "parse_hfs(): Error while parsing Expires header field\n");			return -9;		}	}	if (_m->accept) {		if (parse_accept(_m->accept, &acc) < 0) {			paerrno = PA_ACCEPT_PARSE;			LOG(L_ERR, "parse_hfs(): Error while parsing Accept header field\n");			return -10;		}	} else if (accept_header_required) {		LOG(L_ERR, "no accept header\n");		acc = DOC_XPIDF;	}	return 0;}