/* Construct a domain name for SRV query from the given name, service and
* protocol (service may be NULL in which case protocol isn't used).
* Return negative value on error (malformed query),
* or addition query flag(s) to use.
*/
static int
build_srv_dn(dnsc_t *dn, const char *name, const char *srv, const char *proto)
{
unsigned p = 0, l;
int isabs;
if (srv) {
l = add_sname(dn + p, srv);
if (!l)
return -1;
p += l;
l = add_sname(dn + p, proto);
if (!l)
return -1;
p += l;
}
l = dns_ptodn(name, 0, dn + p, DNS_MAXDN - p, &isabs);
if (!l)
return -1;
return isabs ? DNS_NOSRCH : 0;
}
/* Prepare initial DHCPv4 message and add options as per message type */
static struct net_buf *prepare_message(struct net_if *iface, uint8_t type)
{
struct net_buf *buf;
struct net_buf *frag;
struct dhcp_msg *msg;
buf = net_nbuf_get_reserve_tx(0);
if (!buf) {
return NULL;
}
frag = net_nbuf_get_reserve_data(net_if_get_ll_reserve(iface, NULL));
if (!frag) {
goto fail;
}
net_nbuf_set_ll_reserve(buf, net_buf_headroom(frag));
net_nbuf_set_iface(buf, iface);
net_nbuf_set_family(buf, AF_INET);
net_nbuf_set_ip_hdr_len(buf, sizeof(struct net_ipv4_hdr));
net_buf_frag_add(buf, frag);
/* Leave room for IPv4 + UDP headers */
net_buf_add(buf->frags, NET_IPV4UDPH_LEN);
if (net_buf_tailroom(frag) < sizeof(struct dhcp_msg)) {
goto fail;
}
msg = (struct dhcp_msg *)(frag->data + NET_IPV4UDPH_LEN);
memset(msg, 0, sizeof(struct dhcp_msg));
msg->op = DHCPV4_MSG_BOOT_REQUEST;
msg->htype = HARDWARE_ETHERNET_TYPE;
msg->hlen = HARDWARE_ETHERNET_LEN;
msg->xid = htonl(iface->dhcpv4.xid);
msg->flags = htons(DHCPV4_MSG_BROADCAST);
if (iface->dhcpv4.state == NET_DHCPV4_INIT) {
memset(msg->ciaddr, 0, sizeof(msg->ciaddr));
} else {
memcpy(msg->ciaddr, iface->dhcpv4.requested_ip.s4_addr, 4);
}
memcpy(msg->chaddr, iface->link_addr.addr, iface->link_addr.len);
net_buf_add(frag, sizeof(struct dhcp_msg));
if (!add_sname(buf) ||
!add_file(buf) ||
!add_cookie(buf) ||
!add_msg_type(buf, type)) {
goto fail;
}
return buf;
fail:
net_nbuf_unref(buf);
return NULL;
}
