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udhcpd: untangle incredibly messy handling of DHCPREQUEST

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Also fixes attacks possible via DHCPDECLINE / DHCPRELEASE

function                                             old     new   delta
udhcpd_main                                         1846    1949    +103
send_renew                                           105     142     +37
send_NAK                                              61       -     -61
send_ACK                                             180       -    -180
------------------------------------------------------------------------------
(add/remove: 0/2 grow/shrink: 2/0 up/down: 140/-241)         Total: -101 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2010-03-21 06:15:28 +01:00
parent 2e7aa92836
commit c7dc79e71d
9 changed files with 268 additions and 185 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

54
networking/udhcp/clientpacket.c
View File

@ -109,24 +109,6 @@ static int raw_bcast_from_client_config_ifindex(struct dhcp_packet *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
/* Broadcast a DHCP discover packet to the network, with an optionally requested IP */ /* Broadcast a DHCP discover packet to the network, with an optionally requested IP */
int FAST_FUNC send_discover(uint32_t xid, uint32_t requested) int FAST_FUNC send_discover(uint32_t xid, uint32_t requested)
{ {
@ -136,11 +118,9 @@ int FAST_FUNC send_discover(uint32_t xid, uint32_t requested)
packet.xid = xid; packet.xid = xid;
if (requested) if (requested)
add_simple_option(packet.options, DHCP_REQUESTED_IP, requested); add_simple_option(packet.options, DHCP_REQUESTED_IP, requested);
/* Explicitly saying that we want RFC-compliant packets helps /* Explicitly saying that we want RFC-compliant packets helps
* some buggy DHCP servers to NOT send bigger packets */ * some buggy DHCP servers to NOT send bigger packets */
add_simple_option(packet.options, DHCP_MAX_SIZE, htons(576)); add_simple_option(packet.options, DHCP_MAX_SIZE, htons(576));
add_param_req_option(&packet); add_param_req_option(&packet);
bb_info_msg("Sending discover..."); bb_info_msg("Sending discover...");
@ -159,7 +139,6 @@ int FAST_FUNC send_select(uint32_t xid, uint32_t server, uint32_t requested)
init_packet(&packet, DHCPREQUEST); init_packet(&packet, DHCPREQUEST);
packet.xid = xid; packet.xid = xid;
add_simple_option(packet.options, DHCP_REQUESTED_IP, requested); add_simple_option(packet.options, DHCP_REQUESTED_IP, requested);
add_simple_option(packet.options, DHCP_SERVER_ID, server); add_simple_option(packet.options, DHCP_SERVER_ID, server);
add_param_req_option(&packet); add_param_req_option(&packet);
@ -177,19 +156,48 @@ int FAST_FUNC send_renew(uint32_t xid, uint32_t server, uint32_t ciaddr)
init_packet(&packet, DHCPREQUEST); init_packet(&packet, DHCPREQUEST);
packet.xid = xid; 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; 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); add_param_req_option(&packet);
bb_info_msg("Sending renew..."); bb_info_msg("Sending renew...");
if (server) if (server)
return udhcp_send_kernel_packet(&packet, return udhcp_send_kernel_packet(&packet,
ciaddr, CLIENT_PORT, ciaddr, CLIENT_PORT,
server, SERVER_PORT); server, SERVER_PORT);
return raw_bcast_from_client_config_ifindex(&packet); 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 */ /* Unicast a DHCP release message */
int FAST_FUNC send_release(uint32_t server, uint32_t ciaddr) int FAST_FUNC send_release(uint32_t server, uint32_t ciaddr)
{ {

75
networking/udhcp/common.h
View File

@ -21,11 +21,17 @@ extern const uint8_t MAC_BCAST_ADDR[6]; /* six all-ones */
/*** packet.h ***/ /*** 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 //TODO: rename ciaddr/yiaddr/chaddr
struct dhcp_packet { 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 htype; /* hardware address type. 1 = 10mb ethernet */
uint8_t hlen; /* hardware address length */ uint8_t hlen; /* hardware address length */
uint8_t hops; /* used by relay agents only */ uint8_t hops; /* used by relay agents only */
@ -61,6 +67,71 @@ struct BUG_bad_sizeof_struct_ip_udp_dhcp_packet {
[(sizeof(struct ip_udp_dhcp_packet) != 576 + CONFIG_UDHCPC_SLACK_FOR_BUGGY_SERVERS) ? -1 : 1]; [(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; uint16_t udhcp_checksum(void *addr, int count) FAST_FUNC;
void udhcp_init_header(struct dhcp_packet *packet, char type) FAST_FUNC; void udhcp_init_header(struct dhcp_packet *packet, char type) FAST_FUNC;

1
networking/udhcp/dhcpc.h
View File

@ -40,7 +40,6 @@ int send_select(uint32_t xid, uint32_t server, uint32_t requested) FAST_FUNC;
int send_decline(uint32_t xid, uint32_t server, uint32_t requested) FAST_FUNC; int send_decline(uint32_t xid, uint32_t server, uint32_t requested) FAST_FUNC;
#endif #endif
int send_renew(uint32_t xid, uint32_t server, uint32_t ciaddr) FAST_FUNC; int send_renew(uint32_t xid, uint32_t server, uint32_t ciaddr) FAST_FUNC;
int send_renew(uint32_t xid, uint32_t server, uint32_t ciaddr) FAST_FUNC;
int send_release(uint32_t server, uint32_t ciaddr) FAST_FUNC; int send_release(uint32_t server, uint32_t ciaddr) FAST_FUNC;
int udhcp_recv_raw_packet(struct dhcp_packet *dhcp_pkt, int fd) FAST_FUNC; int udhcp_recv_raw_packet(struct dhcp_packet *dhcp_pkt, int fd) FAST_FUNC;

264
networking/udhcp/dhcpd.c
View File

@ -28,18 +28,8 @@
#include "options.h" #include "options.h"
/* send a packet to gateway_nip using the kernel ip stack */ /* Send a packet to a specific mac address and ip address by creating our own ip packet */
static int send_packet_to_relay(struct dhcp_packet *dhcp_pkt) static void send_packet_to_client(struct dhcp_packet *dhcp_pkt, int force_broadcast)
{
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)
{ {
const uint8_t *chaddr; const uint8_t *chaddr;
uint32_t ciaddr; uint32_t ciaddr;
@ -69,25 +59,36 @@ static int send_packet_to_client(struct dhcp_packet *dhcp_pkt, int force_broadca
chaddr = dhcp_pkt->chaddr; chaddr = dhcp_pkt->chaddr;
} }
return udhcp_send_raw_packet(dhcp_pkt, udhcp_send_raw_packet(dhcp_pkt,
/*src*/ server_config.server_nip, SERVER_PORT, /*src*/ server_config.server_nip, SERVER_PORT,
/*dst*/ ciaddr, CLIENT_PORT, chaddr, /*dst*/ ciaddr, CLIENT_PORT, chaddr,
server_config.ifindex); server_config.ifindex);
} }
/* Send the dhcp packet. /* Send a packet to gateway_nip using the kernel ip stack */
* If force broadcast is set, the packet will be broadcast. static void send_packet_to_relay(struct dhcp_packet *dhcp_pkt)
*/ {
static int send_packet(struct dhcp_packet *dhcp_pkt, int force_broadcast) 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) if (dhcp_pkt->gateway_nip)
return send_packet_to_relay(dhcp_pkt); send_packet_to_relay(dhcp_pkt);
return send_packet_to_client(dhcp_pkt, force_broadcast); else
send_packet_to_client(dhcp_pkt, force_broadcast);
} }
static void init_packet(struct dhcp_packet *packet, struct dhcp_packet *oldpacket, char type) 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); udhcp_init_header(packet, type);
packet->xid = oldpacket->xid; packet->xid = oldpacket->xid;
memcpy(packet->chaddr, oldpacket->chaddr, sizeof(oldpacket->chaddr)); memcpy(packet->chaddr, oldpacket->chaddr, sizeof(oldpacket->chaddr));
packet->flags = oldpacket->flags; packet->flags = oldpacket->flags;
@ -132,26 +133,32 @@ static uint32_t select_lease_time(struct dhcp_packet *packet)
return lease_time_sec; return lease_time_sec;
} }
/* send a DHCP OFFER to a DHCP DISCOVER */ /* We got a DHCP DISCOVER. Send an OFFER. */
static int send_offer(struct dhcp_packet *oldpacket, uint32_t static_lease_nip, struct dyn_lease *lease) static void send_offer(struct dhcp_packet *oldpacket, uint32_t static_lease_nip, struct dyn_lease *lease)
{ {
struct dhcp_packet packet; struct dhcp_packet packet;
uint32_t lease_time_sec = server_config.max_lease_sec; uint32_t lease_time_sec;
const char *p_host_name;
struct in_addr addr; struct in_addr addr;
init_packet(&packet, oldpacket, DHCPOFFER); 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) { if (!static_lease_nip) {
/* We have no static lease for client's chaddr */
uint32_t req_nip; uint32_t req_nip;
uint8_t *req_ip_opt; uint8_t *req_ip_opt;
const char *p_host_name;
/* The client is in our lease/offered table */
if (lease) { 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; 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 else if ((req_ip_opt = get_option(oldpacket, DHCP_REQUESTED_IP)) != NULL
/* (read IP) */ /* (read IP) */
&& (move_from_unaligned32(req_nip, req_ip_opt), 1) && (move_from_unaligned32(req_nip, req_ip_opt), 1)
@ -165,50 +172,49 @@ static int send_offer(struct dhcp_packet *oldpacket, uint32_t static_lease_nip,
) { ) {
packet.yiaddr = req_nip; packet.yiaddr = req_nip;
} }
/* Otherwise, find a free IP */
else { else {
/* Otherwise, find a free IP */
packet.yiaddr = find_free_or_expired_nip(oldpacket->chaddr); packet.yiaddr = find_free_or_expired_nip(oldpacket->chaddr);
} }
if (!packet.yiaddr) { if (!packet.yiaddr) {
bb_error_msg("no IP addresses to give - OFFER abandoned"); bb_error_msg("no free IP addresses. OFFER abandoned");
return -1; return;
} }
/* Reserve the IP for a short time hoping to get DHCPREQUEST soon */
p_host_name = (const char*) get_option(oldpacket, DHCP_HOST_NAME); 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, server_config.offer_time,
p_host_name, p_host_name,
p_host_name ? (unsigned char)p_host_name[OPT_LEN - OPT_DATA] : 0 p_host_name ? (unsigned char)p_host_name[OPT_LEN - OPT_DATA] : 0
) == 0 );
) { if (!lease) {
bb_error_msg("lease pool is full - OFFER abandoned"); bb_error_msg("no free IP addresses. OFFER abandoned");
return -1; 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_simple_option(packet.options, DHCP_LEASE_TIME, htonl(lease_time_sec));
add_server_options(&packet); add_server_options(&packet);
addr.s_addr = packet.yiaddr; addr.s_addr = packet.yiaddr;
bb_info_msg("Sending OFFER of %s", inet_ntoa(addr)); 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; struct dhcp_packet packet;
init_packet(&packet, oldpacket, DHCPNAK); init_packet(&packet, oldpacket, DHCPNAK);
log1("Sending NAK"); 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; struct dhcp_packet packet;
uint32_t lease_time_sec; uint32_t lease_time_sec;
@ -219,15 +225,13 @@ static int send_ACK(struct dhcp_packet *oldpacket, uint32_t yiaddr)
packet.yiaddr = yiaddr; packet.yiaddr = yiaddr;
lease_time_sec = select_lease_time(oldpacket); lease_time_sec = select_lease_time(oldpacket);
add_simple_option(packet.options, DHCP_LEASE_TIME, htonl(lease_time_sec)); add_simple_option(packet.options, DHCP_LEASE_TIME, htonl(lease_time_sec));
add_server_options(&packet); add_server_options(&packet);
addr.s_addr = packet.yiaddr; addr.s_addr = yiaddr;
bb_info_msg("Sending ACK to %s", inet_ntoa(addr)); bb_info_msg("Sending ACK to %s", inet_ntoa(addr));
send_packet(&packet, /*force_bcast:*/ 0);
if (send_packet(&packet, /*force_bcast:*/ 0) < 0)
return -1;
p_host_name = (const char*) get_option(oldpacket, DHCP_HOST_NAME); p_host_name = (const char*) get_option(oldpacket, DHCP_HOST_NAME);
add_lease(packet.chaddr, packet.yiaddr, add_lease(packet.chaddr, packet.yiaddr,
@ -239,18 +243,21 @@ static int send_ACK(struct dhcp_packet *oldpacket, uint32_t yiaddr)
/* rewrite the file with leases at every new acceptance */ /* rewrite the file with leases at every new acceptance */
write_leases(); write_leases();
} }
return 0;
} }
static int send_inform(struct dhcp_packet *oldpacket) static void send_inform(struct dhcp_packet *oldpacket)
{ {
struct dhcp_packet packet; 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); init_packet(&packet, oldpacket, DHCPACK);
add_server_options(&packet); add_server_options(&packet);
return send_packet(&packet, /*force_bcast:*/ 0); send_packet(&packet, /*force_bcast:*/ 0);
} }
@ -352,6 +359,9 @@ int udhcpd_main(int argc UNUSED_PARAM, char **argv)
while (1) { /* loop until universe collapses */ while (1) { /* loop until universe collapses */
int bytes; int bytes;
struct timeval tv; struct timeval tv;
uint8_t *server_id_opt;
uint8_t *requested_opt;
uint32_t requested_nip = requested_nip; /* for compiler */
if (server_socket < 0) { if (server_socket < 0) {
server_socket = udhcp_listen_socket(/*INADDR_ANY,*/ SERVER_PORT, server_socket = udhcp_listen_socket(/*INADDR_ANY,*/ SERVER_PORT,
@ -404,124 +414,126 @@ int udhcpd_main(int argc UNUSED_PARAM, char **argv)
} }
continue; continue;
} }
if (packet.hlen != 6) { if (packet.hlen != 6) {
bb_error_msg("MAC length != 6, ignoring packet"); bb_error_msg("MAC length != 6, ignoring packet");
continue; continue;
} }
if (packet.op != BOOTREQUEST) {
bb_error_msg("not a REQUEST, ignoring packet");
continue;
}
state = get_option(&packet, DHCP_MESSAGE_TYPE); state = get_option(&packet, DHCP_MESSAGE_TYPE);
if (state == NULL) { if (state == NULL || state[0] < DHCP_MINTYPE || state[0] > DHCP_MAXTYPE) {
bb_error_msg("no message type option, ignoring packet"); bb_error_msg("no or bad message type option, ignoring packet");
continue; 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); static_lease_nip = get_static_nip_by_mac(server_config.static_leases, &packet.chaddr);
if (static_lease_nip) { if (static_lease_nip) {
bb_info_msg("Found static lease: %x", static_lease_nip); bb_info_msg("Found static lease: %x", static_lease_nip);
memcpy(&fake_lease.lease_mac, &packet.chaddr, 6); memcpy(&fake_lease.lease_mac, &packet.chaddr, 6);
fake_lease.lease_nip = static_lease_nip; fake_lease.lease_nip = static_lease_nip;
fake_lease.expires = 0; fake_lease.expires = 0;
lease = &fake_lease; lease = &fake_lease;
} else { } else {
lease = find_lease_by_mac(packet.chaddr); 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]) { switch (state[0]) {
case DHCPDISCOVER: case DHCPDISCOVER:
log1("Received DISCOVER"); log1("Received DISCOVER");
if (send_offer(&packet, static_lease_nip, lease) < 0) { send_offer(&packet, static_lease_nip, lease);
bb_error_msg("send OFFER failed");
}
break; 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"); log1("Received REQUEST");
requested_opt = get_option(&packet, DHCP_REQUESTED_IP); /* RFC 2131: "The REQUESTED_IP option MUST be set
server_id_opt = get_option(&packet, DHCP_SERVER_ID); * to the value of 'yiaddr' in the DHCPOFFER message
if (requested_opt) * from the server." */
move_from_unaligned32(requested_nip, requested_opt); if (!requested_opt) {
if (server_id_opt) log1("no requested IP, ignoring");
move_from_unaligned32(server_id_net, server_id_opt); break;
}
if (lease) { if (lease && requested_nip == lease->lease_nip) {
if (server_id_opt) { /* client requests IP which matches the lease.
/* SELECTING State */ * ACK it, and bump lease expiration time. */
if (server_id_net == server_config.server_nip send_ACK(&packet, lease->lease_nip);
&& requested_opt break;
&& requested_nip == lease->lease_nip }
) { if (server_id_opt) {
send_ACK(&packet, lease->lease_nip); /* client was talking specifically to us.
} * "No, we don't have this IP for you". */
} else if (requested_opt) { send_NAK(&packet);
/* 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 */
} }
break; break;
}
case DHCPDECLINE: 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"); 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)); memset(lease->lease_mac, 0, sizeof(lease->lease_mac));
lease->expires = time(NULL) + server_config.decline_time; lease->expires = time(NULL) + server_config.decline_time;
} }
break; break;
case DHCPRELEASE: 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"); log1("Received RELEASE");
if (lease) if (server_id_opt
&& lease /* chaddr matches this lease */
&& packet.ciaddr == lease->lease_nip
) {
lease->expires = time(NULL); lease->expires = time(NULL);
}
break; break;
case DHCPINFORM: case DHCPINFORM:
log1("Received INFORM"); log1("Received INFORM");
send_inform(&packet); send_inform(&packet);
break; break;
default:
bb_info_msg("Unsupported DHCP message (%02x) - ignoring", state[0]);
} }
} }
ret0: ret0:

14
networking/udhcp/files.c
View File

@ -99,7 +99,7 @@ static void attach_option(struct option_set **opt_list,
log2("Attaching option %02x to list", option->code); log2("Attaching option %02x to list", option->code);
#if ENABLE_FEATURE_UDHCP_RFC3397 #if ENABLE_FEATURE_UDHCP_RFC3397
if ((option->flags & TYPE_MASK) == OPTION_STR1035) if ((option->flags & OPTION_TYPE_MASK) == OPTION_STR1035)
/* reuse buffer and length for RFC1035-formatted string */ /* reuse buffer and length for RFC1035-formatted string */
buffer = (char *)dname_enc(NULL, 0, buffer, &length); buffer = (char *)dname_enc(NULL, 0, buffer, &length);
#endif #endif
@ -118,7 +118,7 @@ static void attach_option(struct option_set **opt_list,
new->next = *curr; new->next = *curr;
*curr = new; *curr = new;
#if ENABLE_FEATURE_UDHCP_RFC3397 #if ENABLE_FEATURE_UDHCP_RFC3397
if ((option->flags & TYPE_MASK) == OPTION_STR1035 && buffer != NULL) if ((option->flags & OPTION_TYPE_MASK) == OPTION_STR1035 && buffer != NULL)
free(buffer); free(buffer);
#endif #endif
return; return;
@ -128,7 +128,7 @@ static void attach_option(struct option_set **opt_list,
log1("Attaching option %02x to existing member of list", option->code); log1("Attaching option %02x to existing member of list", option->code);
if (option->flags & OPTION_LIST) { if (option->flags & OPTION_LIST) {
#if ENABLE_FEATURE_UDHCP_RFC3397 #if ENABLE_FEATURE_UDHCP_RFC3397
if ((option->flags & TYPE_MASK) == OPTION_STR1035) if ((option->flags & OPTION_TYPE_MASK) == OPTION_STR1035)
/* reuse buffer and length for RFC1035-formatted string */ /* reuse buffer and length for RFC1035-formatted string */
buffer = (char *)dname_enc(existing->data + 2, buffer = (char *)dname_enc(existing->data + 2,
existing->data[OPT_LEN], buffer, &length); existing->data[OPT_LEN], buffer, &length);
@ -136,7 +136,7 @@ static void attach_option(struct option_set **opt_list,
if (existing->data[OPT_LEN] + length <= 255) { if (existing->data[OPT_LEN] + length <= 255) {
existing->data = xrealloc(existing->data, existing->data = xrealloc(existing->data,
existing->data[OPT_LEN] + length + 3); existing->data[OPT_LEN] + length + 3);
if ((option->flags & TYPE_MASK) == OPTION_STRING) { if ((option->flags & OPTION_TYPE_MASK) == OPTION_STRING) {
/* ' ' can bring us to 256 - bad */ /* ' ' can bring us to 256 - bad */
if (existing->data[OPT_LEN] + length >= 255) if (existing->data[OPT_LEN] + length >= 255)
return; return;
@ -148,7 +148,7 @@ static void attach_option(struct option_set **opt_list,
existing->data[OPT_LEN] += length; existing->data[OPT_LEN] += length;
} /* else, ignore the data, we could put this in a second option in the future */ } /* else, ignore the data, we could put this in a second option in the future */
#if ENABLE_FEATURE_UDHCP_RFC3397 #if ENABLE_FEATURE_UDHCP_RFC3397
if ((option->flags & TYPE_MASK) == OPTION_STR1035 && buffer != NULL) if ((option->flags & OPTION_TYPE_MASK) == OPTION_STR1035 && buffer != NULL)
free(buffer); free(buffer);
#endif #endif
} /* else, ignore the new data */ } /* else, ignore the new data */
@ -182,10 +182,10 @@ static int FAST_FUNC read_opt(const char *const_line, void *arg)
do { do {
val = strtok(NULL, ", \t"); val = strtok(NULL, ", \t");
if (!val) break; if (!val) break;
length = dhcp_option_lengths[option->flags & TYPE_MASK]; length = dhcp_option_lengths[option->flags & OPTION_TYPE_MASK];
retval = 0; retval = 0;
opt = buffer; /* new meaning for variable opt */ opt = buffer; /* new meaning for variable opt */
switch (option->flags & TYPE_MASK) { switch (option->flags & OPTION_TYPE_MASK) {
case OPTION_IP: case OPTION_IP:
retval = read_nip(val, buffer); retval = read_nip(val, buffer);
break; break;

2
networking/udhcp/options.c
View File

@ -252,7 +252,7 @@ void FAST_FUNC add_simple_option(uint8_t *optionptr, uint8_t code, uint32_t data
uint8_t option[6], len; uint8_t option[6], len;
option[OPT_CODE] = code; option[OPT_CODE] = code;
len = dhcp_option_lengths[dh->flags & TYPE_MASK]; len = dhcp_option_lengths[dh->flags & OPTION_TYPE_MASK];
option[OPT_LEN] = len; option[OPT_LEN] = len;
if (BB_BIG_ENDIAN) if (BB_BIG_ENDIAN)
data <<= 8 * (4 - len); data <<= 8 * (4 - len);

30
networking/udhcp/options.h
View File

@ -5,7 +5,6 @@
PUSH_AND_SET_FUNCTION_VISIBILITY_TO_HIDDEN PUSH_AND_SET_FUNCTION_VISIBILITY_TO_HIDDEN
#define TYPE_MASK 0x0F
enum { enum {
OPTION_IP = 1, OPTION_IP = 1,
@ -21,20 +20,14 @@ enum {
OPTION_U32, OPTION_U32,
OPTION_S32, OPTION_S32,
OPTION_STATIC_ROUTES, OPTION_STATIC_ROUTES,
OPTION_TYPE_MASK = 0x0f,
/* Client requests this option by default */
OPTION_REQ = 0x10,
/* There can be a list of 1 or more of these */
OPTION_LIST = 0x20,
}; };
/* Client requests this option by default */
#define OPTION_REQ 0x10
/* There can be a list of 1 or more of these */
#define OPTION_LIST 0x20
/*****************************************************************/
/* Do not modify below here unless you know what you are doing!! */
/*****************************************************************/
/* DHCP protocol. See RFC 2131 */
#define DHCP_MAGIC 0x63825363
/* DHCP option codes (partial list). See RFC 2132 and /* DHCP option codes (partial list). See RFC 2132 and
* http://www.iana.org/assignments/bootp-dhcp-parameters/ * http://www.iana.org/assignments/bootp-dhcp-parameters/
* Commented out options are handled by common option machinery, * Commented out options are handled by common option machinery,
@ -81,7 +74,6 @@ enum {
//#define DHCP_WPAD 0xfc /* MSIE's Web Proxy Autodiscovery Protocol */ //#define DHCP_WPAD 0xfc /* MSIE's Web Proxy Autodiscovery Protocol */
#define DHCP_END 0xff #define DHCP_END 0xff
/* Offsets in option byte sequence */ /* Offsets in option byte sequence */
#define OPT_CODE 0 #define OPT_CODE 0
#define OPT_LEN 1 #define OPT_LEN 1
@ -91,12 +83,7 @@ enum {
#define FILE_FIELD 1 #define FILE_FIELD 1
#define SNAME_FIELD 2 #define SNAME_FIELD 2
#define BOOTREQUEST 1 /* DHCP_MESSAGE_TYPE values */
#define BOOTREPLY 2
#define ETH_10MB 1
#define ETH_10MB_LEN 6
#define DHCPDISCOVER 1 /* client -> server */ #define DHCPDISCOVER 1 /* client -> server */
#define DHCPOFFER 2 /* client <- server */ #define DHCPOFFER 2 /* client <- server */
#define DHCPREQUEST 3 /* client -> server */ #define DHCPREQUEST 3 /* client -> server */
@ -105,6 +92,9 @@ enum {
#define DHCPNAK 6 /* client <- server */ #define DHCPNAK 6 /* client <- server */
#define DHCPRELEASE 7 /* client -> server */ #define DHCPRELEASE 7 /* client -> server */
#define DHCPINFORM 8 /* client -> server */ #define DHCPINFORM 8 /* client -> server */
#define DHCP_MINTYPE DHCPDISCOVER
#define DHCP_MAXTYPE DHCPINFORM
struct dhcp_option { struct dhcp_option {
uint8_t flags; uint8_t flags;

11
networking/udhcp/packet.c
View File

@ -21,7 +21,7 @@
void FAST_FUNC udhcp_init_header(struct dhcp_packet *packet, char type) void FAST_FUNC udhcp_init_header(struct dhcp_packet *packet, char type)
{ {
memset(packet, 0, sizeof(struct dhcp_packet)); memset(packet, 0, sizeof(*packet));
packet->op = BOOTREQUEST; /* if client to a server */ packet->op = BOOTREQUEST; /* if client to a server */
switch (type) { switch (type) {
case DHCPOFFER: case DHCPOFFER:
@ -29,10 +29,11 @@ void FAST_FUNC udhcp_init_header(struct dhcp_packet *packet, char type)
case DHCPNAK: case DHCPNAK:
packet->op = BOOTREPLY; /* if server to client */ packet->op = BOOTREPLY; /* if server to client */
} }
packet->htype = ETH_10MB; packet->htype = 1; /* ethernet */
packet->hlen = ETH_10MB_LEN; packet->hlen = 6;
packet->cookie = htonl(DHCP_MAGIC); packet->cookie = htonl(DHCP_MAGIC);
packet->options[0] = DHCP_END; if (DHCP_END != 0)
packet->options[0] = DHCP_END;
add_simple_option(packet->options, DHCP_MESSAGE_TYPE, type); add_simple_option(packet->options, DHCP_MESSAGE_TYPE, type);
} }
@ -228,6 +229,7 @@ int FAST_FUNC udhcp_send_raw_packet(struct dhcp_packet *dhcp_pkt,
msg = "sendto"; msg = "sendto";
ret_close: ret_close:
close(fd); close(fd);
/* FIXME: and if result >= 0 but != IP_UPD_DHCP_SIZE? */
if (result < 0) { if (result < 0) {
ret_msg: ret_msg:
bb_perror_msg(msg, "PACKET"); bb_perror_msg(msg, "PACKET");
@ -280,6 +282,7 @@ int FAST_FUNC udhcp_send_kernel_packet(struct dhcp_packet *dhcp_pkt,
msg = "write"; msg = "write";
ret_close: ret_close:
close(fd); close(fd);
/* FIXME: and if result >= 0 but != DHCP_SIZE? */
if (result < 0) { if (result < 0) {
ret_msg: ret_msg:
bb_perror_msg(msg, "UDP"); bb_perror_msg(msg, "UDP");

2
networking/udhcp/script.c
View File

@ -64,7 +64,7 @@ static NOINLINE char *xmalloc_optname_optval(uint8_t *option, const struct dhcp_
/* option points to OPT_DATA, need to go back and get OPT_LEN */ /* option points to OPT_DATA, need to go back and get OPT_LEN */
len = option[OPT_LEN - OPT_DATA]; len = option[OPT_LEN - OPT_DATA];
type = type_p->flags & TYPE_MASK; type = type_p->flags & OPTION_TYPE_MASK;
optlen = dhcp_option_lengths[type]; optlen = dhcp_option_lengths[type];
upper_length = len_of_option_as_string[type] * (len / optlen); upper_length = len_of_option_as_string[type] * (len / optlen);