}
-#if ENABLE_FEATURE_UDHCPC_ARPING
-/* Broadcast a DHCP decline message */
-int FAST_FUNC send_decline(uint32_t xid, uint32_t server, uint32_t requested)
-{
- struct dhcp_packet packet;
-
- init_packet(&packet, DHCPDECLINE);
- packet.xid = xid;
- add_simple_option(packet.options, DHCP_REQUESTED_IP, requested);
- add_simple_option(packet.options, DHCP_SERVER_ID, server);
-
- bb_info_msg("Sending decline...");
-
- return raw_bcast_from_client_config_ifindex(&packet);
-}
-#endif
-
-
/* Broadcast a DHCP discover packet to the network, with an optionally requested IP */
int FAST_FUNC send_discover(uint32_t xid, uint32_t requested)
{
packet.xid = xid;
if (requested)
add_simple_option(packet.options, DHCP_REQUESTED_IP, requested);
-
/* Explicitly saying that we want RFC-compliant packets helps
* some buggy DHCP servers to NOT send bigger packets */
add_simple_option(packet.options, DHCP_MAX_SIZE, htons(576));
-
add_param_req_option(&packet);
bb_info_msg("Sending discover...");
init_packet(&packet, DHCPREQUEST);
packet.xid = xid;
-
add_simple_option(packet.options, DHCP_REQUESTED_IP, requested);
add_simple_option(packet.options, DHCP_SERVER_ID, server);
add_param_req_option(&packet);
init_packet(&packet, DHCPREQUEST);
packet.xid = xid;
+ /* RFC 2131:
+ * "3.2 Client-server interaction - reusing a previously
+ * allocated network address"...
+ * The client broadcasts a DHCPREQUEST message on its local subnet.
+ * The message includes the client's network address in the
+ * REQUESTED_IP option. As the client has not received its
+ * network address, it MUST NOT fill in the 'ciaddr' field."
+ *
+ * FIXME: we seem to not follow this, we do set ciaddr.
+ */
packet.ciaddr = ciaddr;
-
+ add_simple_option(packet.options, DHCP_REQUESTED_IP, ciaddr);
+ if (server)
+ add_simple_option(packet.options, DHCP_SERVER_ID, server);
add_param_req_option(&packet);
+
bb_info_msg("Sending renew...");
if (server)
return udhcp_send_kernel_packet(&packet,
ciaddr, CLIENT_PORT,
server, SERVER_PORT);
+ return raw_bcast_from_client_config_ifindex(&packet);
+}
+
+
+#if ENABLE_FEATURE_UDHCPC_ARPING
+/* Broadcast a DHCP decline message */
+int FAST_FUNC send_decline(uint32_t xid, uint32_t server, uint32_t requested)
+{
+ struct dhcp_packet packet;
+
+ init_packet(&packet, DHCPDECLINE);
+ packet.xid = xid;
+ add_simple_option(packet.options, DHCP_REQUESTED_IP, requested);
+ add_simple_option(packet.options, DHCP_SERVER_ID, server);
+ bb_info_msg("Sending decline...");
return raw_bcast_from_client_config_ifindex(&packet);
}
+#endif
/* Unicast a DHCP release message */
/*** packet.h ***/
-#define DHCP_OPTIONS_BUFSIZE 308
+/* DHCP protocol. See RFC 2131 */
+#define DHCP_MAGIC 0x63825363
+
+#define DHCP_OPTIONS_BUFSIZE 308
+
+#define BOOTREQUEST 1
+#define BOOTREPLY 2
//TODO: rename ciaddr/yiaddr/chaddr
struct dhcp_packet {
- uint8_t op; /* 1 = BOOTREQUEST, 2 = BOOTREPLY */
+ uint8_t op; /* BOOTREQUEST or BOOTREPLY */
uint8_t htype; /* hardware address type. 1 = 10mb ethernet */
uint8_t hlen; /* hardware address length */
uint8_t hops; /* used by relay agents only */
[(sizeof(struct ip_udp_dhcp_packet) != 576 + CONFIG_UDHCPC_SLACK_FOR_BUGGY_SERVERS) ? -1 : 1];
};
+// RFC 2131 Table 5: Fields and options used by DHCP clients
+//
+// Field DHCPDISCOVER DHCPREQUEST DHCPDECLINE,
+// DHCPINFORM DHCPRELEASE
+// ----- ------------ ----------- -----------
+// 'op' BOOTREQUEST BOOTREQUEST BOOTREQUEST
+// 'hops' 0 0 0
+// 'xid' selected by client 'xid' from server selected by
+// DHCPOFFER message client
+// 'secs' 0 or seconds since 0 or seconds since 0
+// DHCP process started DHCP process started
+// 'flags' Set 'BROADCAST' Set 'BROADCAST' 0
+// flag if client flag if client
+// requires broadcast requires broadcast
+// reply reply
+// 'ciaddr' 0 (DHCPDISCOVER) 0 or client's 0 (DHCPDECLINE)
+// client's network address client's network
+// network address (BOUND/RENEW/REBIND) address
+// (DHCPINFORM) (DHCPRELEASE)
+// 'yiaddr' 0 0 0
+// 'siaddr' 0 0 0
+// 'giaddr' 0 0 0
+// 'chaddr' client's hardware client's hardware client's hardware
+// address address address
+// 'sname' options, if options, if (unused)
+// indicated in indicated in
+// 'sname/file' 'sname/file'
+// option; otherwise option; otherwise
+// unused unused
+// 'file' options, if options, if (unused)
+// indicated in indicated in
+// 'sname/file' 'sname/file'
+// option; otherwise option; otherwise
+// unused unused
+// 'options' options options (unused)
+//
+// Option DHCPDISCOVER DHCPREQUEST DHCPDECLINE,
+// DHCPINFORM DHCPRELEASE
+// ------ ------------ ----------- -----------
+// Requested IP address MAY MUST (in MUST
+// (DISCOVER) SELECTING or (DHCPDECLINE),
+// MUST NOT INIT-REBOOT) MUST NOT
+// (INFORM) MUST NOT (in (DHCPRELEASE)
+// BOUND or
+// RENEWING)
+// IP address lease time MAY MAY MUST NOT
+// (DISCOVER)
+// MUST NOT
+// (INFORM)
+// Use 'file'/'sname' fields MAY MAY MAY
+// Client identifier MAY MAY MAY
+// Vendor class identifier MAY MAY MUST NOT
+// Server identifier MUST NOT MUST (after MUST
+// SELECTING)
+// MUST NOT (after
+// INIT-REBOOT,
+// BOUND, RENEWING
+// or REBINDING)
+// Parameter request list MAY MAY MUST NOT
+// Maximum message size MAY MAY MUST NOT
+// Message SHOULD NOT SHOULD NOT SHOULD
+// Site-specific MAY MAY MUST NOT
+// All others MAY MAY MUST NOT
+
+
uint16_t udhcp_checksum(void *addr, int count) FAST_FUNC;
void udhcp_init_header(struct dhcp_packet *packet, char type) FAST_FUNC;
#include "options.h"
-/* send a packet to gateway_nip using the kernel ip stack */
-static int send_packet_to_relay(struct dhcp_packet *dhcp_pkt)
-{
- log1("Forwarding packet to relay");
-
- return udhcp_send_kernel_packet(dhcp_pkt,
- server_config.server_nip, SERVER_PORT,
- dhcp_pkt->gateway_nip, SERVER_PORT);
-}
-
-/* send a packet to a specific mac address and ip address by creating our own ip packet */
-static int send_packet_to_client(struct dhcp_packet *dhcp_pkt, int force_broadcast)
+/* Send a packet to a specific mac address and ip address by creating our own ip packet */
+static void send_packet_to_client(struct dhcp_packet *dhcp_pkt, int force_broadcast)
{
const uint8_t *chaddr;
uint32_t ciaddr;
chaddr = dhcp_pkt->chaddr;
}
- return udhcp_send_raw_packet(dhcp_pkt,
+ udhcp_send_raw_packet(dhcp_pkt,
/*src*/ server_config.server_nip, SERVER_PORT,
/*dst*/ ciaddr, CLIENT_PORT, chaddr,
server_config.ifindex);
}
-/* Send the dhcp packet.
- * If force broadcast is set, the packet will be broadcast.
- */
-static int send_packet(struct dhcp_packet *dhcp_pkt, int force_broadcast)
+/* Send a packet to gateway_nip using the kernel ip stack */
+static void send_packet_to_relay(struct dhcp_packet *dhcp_pkt)
+{
+ log1("Forwarding packet to relay");
+
+ udhcp_send_kernel_packet(dhcp_pkt,
+ server_config.server_nip, SERVER_PORT,
+ dhcp_pkt->gateway_nip, SERVER_PORT);
+}
+
+static void send_packet(struct dhcp_packet *dhcp_pkt, int force_broadcast)
{
if (dhcp_pkt->gateway_nip)
- return send_packet_to_relay(dhcp_pkt);
- return send_packet_to_client(dhcp_pkt, force_broadcast);
+ send_packet_to_relay(dhcp_pkt);
+ else
+ send_packet_to_client(dhcp_pkt, force_broadcast);
}
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;
return lease_time_sec;
}
-/* send a DHCP OFFER to a DHCP DISCOVER */
-static int send_offer(struct dhcp_packet *oldpacket, uint32_t static_lease_nip, struct dyn_lease *lease)
+/* We got a DHCP DISCOVER. Send an OFFER. */
+static void send_offer(struct dhcp_packet *oldpacket, uint32_t static_lease_nip, struct dyn_lease *lease)
{
struct dhcp_packet packet;
- uint32_t lease_time_sec = server_config.max_lease_sec;
- const char *p_host_name;
+ uint32_t lease_time_sec;
struct in_addr addr;
init_packet(&packet, oldpacket, DHCPOFFER);
- /* ADDME: if static, short circuit */
+ /* 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;
uint8_t *req_ip_opt;
+ const char *p_host_name;
- /* The client is in our lease/offered table */
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 the client has requested an IP */
+ /* Or: if client has requested an IP */
else if ((req_ip_opt = get_option(oldpacket, DHCP_REQUESTED_IP)) != NULL
/* (read IP) */
&& (move_from_unaligned32(req_nip, req_ip_opt), 1)
) {
packet.yiaddr = req_nip;
}
- /* Otherwise, find a free IP */
else {
+ /* Otherwise, find a free IP */
packet.yiaddr = find_free_or_expired_nip(oldpacket->chaddr);
}
if (!packet.yiaddr) {
- bb_error_msg("no IP addresses to give - OFFER abandoned");
- return -1;
+ 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*) get_option(oldpacket, DHCP_HOST_NAME);
- if (add_lease(packet.chaddr, packet.yiaddr,
+ 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
- ) == 0
- ) {
- bb_error_msg("lease pool is full - OFFER abandoned");
- return -1;
+ );
+ if (!lease) {
+ bb_error_msg("no free IP addresses. OFFER abandoned");
+ return;
}
- lease_time_sec = select_lease_time(oldpacket);
- } else {
- /* It is a static lease... use it */
- packet.yiaddr = static_lease_nip;
}
+ lease_time_sec = select_lease_time(oldpacket);
add_simple_option(packet.options, 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));
- return send_packet(&packet, /*force_bcast:*/ 0);
+ /* send_packet emits error message itself if it detects failure */
+ send_packet(&packet, /*force_bcast:*/ 0);
}
-static int send_NAK(struct dhcp_packet *oldpacket)
+static void send_NAK(struct dhcp_packet *oldpacket)
{
struct dhcp_packet packet;
init_packet(&packet, oldpacket, DHCPNAK);
log1("Sending NAK");
- return send_packet(&packet, /*force_bcast:*/ 1);
+ send_packet(&packet, /*force_bcast:*/ 1);
}
-static int send_ACK(struct dhcp_packet *oldpacket, uint32_t yiaddr)
+static void send_ACK(struct dhcp_packet *oldpacket, uint32_t yiaddr)
{
struct dhcp_packet packet;
uint32_t lease_time_sec;
packet.yiaddr = yiaddr;
lease_time_sec = select_lease_time(oldpacket);
-
add_simple_option(packet.options, DHCP_LEASE_TIME, htonl(lease_time_sec));
+
add_server_options(&packet);
- addr.s_addr = packet.yiaddr;
+ addr.s_addr = yiaddr;
bb_info_msg("Sending ACK to %s", inet_ntoa(addr));
-
- if (send_packet(&packet, /*force_bcast:*/ 0) < 0)
- return -1;
+ send_packet(&packet, /*force_bcast:*/ 0);
p_host_name = (const char*) get_option(oldpacket, DHCP_HOST_NAME);
add_lease(packet.chaddr, packet.yiaddr,
/* rewrite the file with leases at every new acceptance */
write_leases();
}
-
- return 0;
}
-static int send_inform(struct dhcp_packet *oldpacket)
+static void send_inform(struct dhcp_packet *oldpacket)
{
struct dhcp_packet packet;
+ /* "The server responds to a DHCPINFORM message by sending a DHCPACK
+ * message directly to the address given in the 'ciaddr' field
+ * of the DHCPINFORM message. The server MUST NOT send a lease
+ * expiration time to the client and SHOULD NOT fill in 'yiaddr'."
+ */
init_packet(&packet, oldpacket, DHCPACK);
add_server_options(&packet);
- return send_packet(&packet, /*force_bcast:*/ 0);
+ send_packet(&packet, /*force_bcast:*/ 0);
}
while (1) { /* loop until universe collapses */
int bytes;
struct timeval tv;
+ uint8_t *server_id_opt;
+ uint8_t *requested_opt;
+ uint32_t requested_nip = requested_nip; /* for compiler */
if (server_socket < 0) {
server_socket = udhcp_listen_socket(/*INADDR_ANY,*/ SERVER_PORT,
}
continue;
}
-
if (packet.hlen != 6) {
bb_error_msg("MAC length != 6, ignoring packet");
continue;
}
-
+ if (packet.op != BOOTREQUEST) {
+ bb_error_msg("not a REQUEST, ignoring packet");
+ continue;
+ }
state = get_option(&packet, DHCP_MESSAGE_TYPE);
- if (state == NULL) {
- bb_error_msg("no message type option, ignoring packet");
+ if (state == NULL || state[0] < DHCP_MINTYPE || state[0] > DHCP_MAXTYPE) {
+ bb_error_msg("no or bad message type option, ignoring packet");
continue;
}
- /* Look for a static lease */
+ /* Look for a static/dynamic lease */
static_lease_nip = get_static_nip_by_mac(server_config.static_leases, &packet.chaddr);
if (static_lease_nip) {
bb_info_msg("Found static lease: %x", static_lease_nip);
-
memcpy(&fake_lease.lease_mac, &packet.chaddr, 6);
fake_lease.lease_nip = static_lease_nip;
fake_lease.expires = 0;
-
lease = &fake_lease;
} else {
lease = find_lease_by_mac(packet.chaddr);
}
+ /* Get REQUESTED_IP and SERVER_ID if present */
+ server_id_opt = get_option(&packet, DHCP_SERVER_ID);
+ if (server_id_opt) {
+ uint32_t server_id_net;
+ move_from_unaligned32(server_id_net, server_id_opt);
+ if (server_id_net != server_config.server_nip) {
+ /* client talks to somebody else */
+ log1("server ID doesn't match, ignoring");
+ continue;
+ }
+ }
+ requested_opt = get_option(&packet, DHCP_REQUESTED_IP);
+ if (requested_opt) {
+ move_from_unaligned32(requested_nip, requested_opt);
+ }
+
switch (state[0]) {
+
case DHCPDISCOVER:
log1("Received DISCOVER");
- if (send_offer(&packet, static_lease_nip, lease) < 0) {
- bb_error_msg("send OFFER failed");
- }
+ send_offer(&packet, static_lease_nip, lease);
break;
- case DHCPREQUEST: {
- uint8_t *server_id_opt, *requested_opt;
- uint32_t server_id_net = server_id_net; /* for compiler */
- uint32_t requested_nip = requested_nip; /* for compiler */
+ case DHCPREQUEST:
log1("Received REQUEST");
- requested_opt = get_option(&packet, DHCP_REQUESTED_IP);
- server_id_opt = get_option(&packet, DHCP_SERVER_ID);
- if (requested_opt)
- move_from_unaligned32(requested_nip, requested_opt);
- if (server_id_opt)
- move_from_unaligned32(server_id_net, server_id_opt);
-
- if (lease) {
- if (server_id_opt) {
- /* SELECTING State */
- if (server_id_net == server_config.server_nip
- && requested_opt
- && requested_nip == lease->lease_nip
- ) {
- send_ACK(&packet, lease->lease_nip);
- }
- } else if (requested_opt) {
- /* INIT-REBOOT State */
- if (lease->lease_nip == requested_nip)
- send_ACK(&packet, lease->lease_nip);
- else
- send_NAK(&packet);
- } else if (lease->lease_nip == packet.ciaddr) {
- /* RENEWING or REBINDING State */
- send_ACK(&packet, lease->lease_nip);
- } else { /* don't know what to do!!!! */
- send_NAK(&packet);
- }
-
- /* what to do if we have no record of the client */
- } else if (server_id_opt) {
- /* SELECTING State */
-
- } else if (requested_opt) {
- /* INIT-REBOOT State */
- lease = find_lease_by_nip(requested_nip);
- if (lease) {
- if (is_expired_lease(lease)) {
- /* probably best if we drop this lease */
- memset(lease->lease_mac, 0, sizeof(lease->lease_mac));
- } else {
- /* make some contention for this address */
- send_NAK(&packet);
- }
- } else {
- uint32_t r = ntohl(requested_nip);
- if (r < server_config.start_ip
- || r > server_config.end_ip
- ) {
- send_NAK(&packet);
- }
- /* else remain silent */
- }
-
- } else {
- /* RENEWING or REBINDING State */
+ /* RFC 2131: "The REQUESTED_IP option MUST be set
+ * to the value of 'yiaddr' in the DHCPOFFER message
+ * from the server." */
+ if (!requested_opt) {
+ log1("no requested IP, ignoring");
+ break;
+ }
+ if (lease && requested_nip == lease->lease_nip) {
+ /* client requests IP which matches the lease.
+ * ACK it, and bump lease expiration time. */
+ send_ACK(&packet, lease->lease_nip);
+ break;
+ }
+ if (server_id_opt) {
+ /* client was talking specifically to us.
+ * "No, we don't have this IP for you". */
+ send_NAK(&packet);
}
break;
- }
+
case DHCPDECLINE:
+ /* RFC 2131:
+ * "If the server receives a DHCPDECLINE message,
+ * the client has discovered through some other means
+ * that the suggested network address is already
+ * in use. The server MUST mark the network address
+ * as not available and SHOULD notify the local
+ * sysadmin of a possible configuration problem."
+ *
+ * SERVER_ID must be present,
+ * REQUESTED_IP must be present,
+ * chaddr must be filled in,
+ * ciaddr must be 0 (we do not check this)
+ */
log1("Received DECLINE");
- if (lease) {
+ if (server_id_opt
+ && requested_opt
+ && lease /* chaddr matches this lease */
+ && requested_nip == lease->lease_nip
+ ) {
memset(lease->lease_mac, 0, sizeof(lease->lease_mac));
lease->expires = time(NULL) + server_config.decline_time;
}
break;
+
case DHCPRELEASE:
+ /* "Upon receipt of a DHCPRELEASE message, the server
+ * marks the network address as not allocated."
+ *
+ * SERVER_ID must be present,
+ * REQUESTED_IP must not be present (we do not check this),
+ * chaddr must be filled in,
+ * ciaddr must be filled in
+ */
log1("Received RELEASE");
- if (lease)
+ if (server_id_opt
+ && lease /* chaddr matches this lease */
+ && packet.ciaddr == lease->lease_nip
+ ) {
lease->expires = time(NULL);
+ }
break;
+
case DHCPINFORM:
log1("Received INFORM");
send_inform(&packet);
break;
- default:
- bb_info_msg("Unsupported DHCP message (%02x) - ignoring", state[0]);
}
}
ret0:
projects / oweals / busybox.git / commitdiff