/* NOINLINE: limit stack usage in caller */
static NOINLINE void send_ACK(struct dhcp_packet *oldpacket, uint32_t yiaddr)
{
struct dhcp_packet packet;
uint32_t lease_time_sec;
struct in_addr addr;
const char *p_host_name;
init_packet(&packet, oldpacket, DHCPACK);
packet.yiaddr = yiaddr;
lease_time_sec = select_lease_time(oldpacket);
udhcp_add_simple_option(&packet, DHCP_LEASE_TIME, htonl(lease_time_sec));
add_server_options(&packet);
addr.s_addr = yiaddr;
bb_info_msg("Sending ACK to %s", inet_ntoa(addr));
send_packet(&packet, /*force_bcast:*/ 0);
p_host_name = (const char*) udhcp_get_option(oldpacket, DHCP_HOST_NAME);
add_lease(packet.chaddr, packet.yiaddr,
lease_time_sec,
p_host_name,
p_host_name ? (unsigned char)p_host_name[OPT_LEN - OPT_DATA] : 0
);
if (ENABLE_FEATURE_UDHCPD_WRITE_LEASES_EARLY) {
/* rewrite the file with leases at every new acceptance */
write_leases();
}
}
static void init_packet(struct dhcp_packet *packet, struct dhcp_packet *oldpacket, char type)
{
/* Sets op, htype, hlen, cookie fields
* and adds DHCP_MESSAGE_TYPE option */
udhcp_init_header(packet, type);
packet->xid = oldpacket->xid;
memcpy(packet->chaddr, oldpacket->chaddr, sizeof(oldpacket->chaddr));
packet->flags = oldpacket->flags;
packet->gateway_nip = oldpacket->gateway_nip;
packet->ciaddr = oldpacket->ciaddr;
udhcp_add_simple_option(packet, DHCP_SERVER_ID, server_config.server_nip);
}
void FAST_FUNC udhcp_init_header(struct dhcp_packet *packet, char type)
{
memset(packet, 0, sizeof(*packet));
packet->op = BOOTREQUEST; /* if client to a server */
switch (type) {
case DHCPOFFER:
case DHCPACK:
case DHCPNAK:
packet->op = BOOTREPLY; /* if server to client */
}
packet->htype = 1; /* ethernet */
packet->hlen = 6;
packet->cookie = htonl(DHCP_MAGIC);
if (DHCP_END != 0)
packet->options[0] = DHCP_END;
udhcp_add_simple_option(packet, DHCP_MESSAGE_TYPE, type);
}
/* NOINLINE: limit stack usage in caller */
static NOINLINE void send_offer(struct dhcp_packet *oldpacket,
uint32_t static_lease_nip,
struct dyn_lease *lease,
uint8_t *requested_ip_opt,
unsigned arpping_ms)
{
struct dhcp_packet packet;
uint32_t lease_time_sec;
struct in_addr addr;
init_packet(&packet, oldpacket, DHCPOFFER);
/* If it is a static lease, use its IP */
packet.yiaddr = static_lease_nip;
/* Else: */
if (!static_lease_nip) {
/* We have no static lease for client's chaddr */
uint32_t req_nip;
const char *p_host_name;
if (lease) {
/* We have a dynamic lease for client's chaddr.
* Reuse its IP (even if lease is expired).
* Note that we ignore requested IP in this case.
*/
packet.yiaddr = lease->lease_nip;
}
/* Or: if client has requested an IP */
else if (requested_ip_opt != NULL
/* (read IP) */
&& (move_from_unaligned32(req_nip, requested_ip_opt), 1)
/* and the IP is in the lease range */
&& ntohl(req_nip) >= server_config.start_ip
&& ntohl(req_nip) <= server_config.end_ip
/* and */
&& ( !(lease = find_lease_by_nip(req_nip)) /* is not already taken */
|| is_expired_lease(lease) /* or is taken, but expired */
)
) {
packet.yiaddr = req_nip;
}
else {
/* Otherwise, find a free IP */
packet.yiaddr = find_free_or_expired_nip(oldpacket->chaddr, arpping_ms);
}
if (!packet.yiaddr) {
bb_error_msg("no free IP addresses. OFFER abandoned");
return;
}
/* Reserve the IP for a short time hoping to get DHCPREQUEST soon */
p_host_name = (const char*) udhcp_get_option(oldpacket, DHCP_HOST_NAME);
lease = add_lease(packet.chaddr, packet.yiaddr,
server_config.offer_time,
p_host_name,
p_host_name ? (unsigned char)p_host_name[OPT_LEN - OPT_DATA] : 0
);
if (!lease) {
bb_error_msg("no free IP addresses. OFFER abandoned");
return;
}
}
lease_time_sec = select_lease_time(oldpacket);
udhcp_add_simple_option(&packet, DHCP_LEASE_TIME, htonl(lease_time_sec));
add_server_options(&packet);
addr.s_addr = packet.yiaddr;
bb_info_msg("Sending OFFER of %s", inet_ntoa(addr));
/* send_packet emits error message itself if it detects failure */
send_packet(&packet, /*force_bcast:*/ 0);
}