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udhcpd: don't fail ARP check if returned MAC matches client's one

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Also, do not unicast replies to yiaddr.

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2009-06-16 10:20:27 +02:00
parent 1f363a0867
commit 47f2d7ef7d
6 changed files with 67 additions and 34 deletions
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19
networking/udhcp/arpping.c
View File

@ -41,7 +41,11 @@ enum {
/* Returns 1 if no reply received */ /* Returns 1 if no reply received */
int FAST_FUNC arpping(uint32_t test_ip, uint32_t from_ip, uint8_t *from_mac, const char *interface) int FAST_FUNC arpping(uint32_t test_ip,
const uint8_t *safe_mac,
uint32_t from_ip,
uint8_t *from_mac,
const char *interface)
{ {
int timeout_ms; int timeout_ms;
struct pollfd pfd[1]; struct pollfd pfd[1];
@ -73,7 +77,7 @@ int FAST_FUNC arpping(uint32_t test_ip, uint32_t from_ip, uint8_t *from_mac, con
arp.operation = htons(ARPOP_REQUEST); /* ARP op code */ arp.operation = htons(ARPOP_REQUEST); /* ARP op code */
memcpy(arp.sHaddr, from_mac, 6); /* source hardware address */ memcpy(arp.sHaddr, from_mac, 6); /* source hardware address */
memcpy(arp.sInaddr, &from_ip, sizeof(from_ip)); /* source IP address */ memcpy(arp.sInaddr, &from_ip, sizeof(from_ip)); /* source IP address */
/* tHaddr is zero-fiiled */ /* target hardware address */ /* tHaddr is zero-filled */ /* target hardware address */
memcpy(arp.tInaddr, &test_ip, sizeof(test_ip)); /* target IP address */ memcpy(arp.tInaddr, &test_ip, sizeof(test_ip)); /* target IP address */
memset(&addr, 0, sizeof(addr)); memset(&addr, 0, sizeof(addr));
@ -98,13 +102,24 @@ int FAST_FUNC arpping(uint32_t test_ip, uint32_t from_ip, uint8_t *from_mac, con
r = read(s, &arp, sizeof(arp)); r = read(s, &arp, sizeof(arp));
if (r < 0) if (r < 0)
break; break;
//bb_error_msg("sHaddr %02x:%02x:%02x:%02x:%02x:%02x",
// arp.sHaddr[0], arp.sHaddr[1], arp.sHaddr[2],
// arp.sHaddr[3], arp.sHaddr[4], arp.sHaddr[5]);
if (r >= ARP_MSG_SIZE if (r >= ARP_MSG_SIZE
&& arp.operation == htons(ARPOP_REPLY) && arp.operation == htons(ARPOP_REPLY)
/* don't check it: Linux doesn't return proper tHaddr (fixed in 2.6.24?) */ /* don't check it: Linux doesn't return proper tHaddr (fixed in 2.6.24?) */
/* && memcmp(arp.tHaddr, from_mac, 6) == 0 */ /* && memcmp(arp.tHaddr, from_mac, 6) == 0 */
&& *((uint32_t *) arp.sInaddr) == test_ip && *((uint32_t *) arp.sInaddr) == test_ip
) { ) {
/* if ARP source MAC matches safe_mac
* (which is client's MAC), then it's not a conflict
* (client simply already has this IP and replies to ARPs!)
*/
if (!safe_mac || memcmp(safe_mac, arp.sHaddr, 6) != 0)
rv = 0; rv = 0;
//else bb_error_msg("sHaddr == safe_mac");
break; break;
} }
} }

6
networking/udhcp/common.h
View File

@ -92,7 +92,11 @@ int udhcp_read_interface(const char *interface, int *ifindex, uint32_t *addr, ui
int udhcp_raw_socket(int ifindex) FAST_FUNC; int udhcp_raw_socket(int ifindex) FAST_FUNC;
int udhcp_listen_socket(/*uint32_t ip,*/ int port, const char *inf) FAST_FUNC; int udhcp_listen_socket(/*uint32_t ip,*/ int port, const char *inf) FAST_FUNC;
/* Returns 1 if no reply received */ /* Returns 1 if no reply received */
int arpping(uint32_t test_ip, uint32_t from_ip, uint8_t *from_mac, const char *interface) FAST_FUNC; int arpping(uint32_t test_ip,
const uint8_t *safe_mac,
uint32_t from_ip,
uint8_t *from_mac,
const char *interface) FAST_FUNC;
#if ENABLE_UDHCP_DEBUG #if ENABLE_UDHCP_DEBUG
# define DEBUG(str, args...) bb_info_msg("### " str, ## args) # define DEBUG(str, args...) bb_info_msg("### " str, ## args)

1
networking/udhcp/dhcpc.c
View File

@ -553,6 +553,7 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv)
* the client MUST send a DHCPDECLINE message to the server and restarts * the client MUST send a DHCPDECLINE message to the server and restarts
* the configuration process..." */ * the configuration process..." */
if (!arpping(packet.yiaddr, if (!arpping(packet.yiaddr,
NULL,
(uint32_t) 0, (uint32_t) 0,
client_config.arp, client_config.arp,
client_config.interface) client_config.interface)

2
networking/udhcp/dhcpd.h
View File

@ -99,7 +99,7 @@ struct dhcpOfferedAddr *add_lease(
int lease_expired(struct dhcpOfferedAddr *lease) FAST_FUNC; int lease_expired(struct dhcpOfferedAddr *lease) FAST_FUNC;
struct dhcpOfferedAddr *find_lease_by_chaddr(const uint8_t *chaddr) FAST_FUNC; struct dhcpOfferedAddr *find_lease_by_chaddr(const uint8_t *chaddr) FAST_FUNC;
struct dhcpOfferedAddr *find_lease_by_yiaddr(uint32_t yiaddr) FAST_FUNC; struct dhcpOfferedAddr *find_lease_by_yiaddr(uint32_t yiaddr) FAST_FUNC;
uint32_t find_free_or_expired_address(void) FAST_FUNC; uint32_t find_free_or_expired_address(const uint8_t *chaddr) FAST_FUNC;
/*** static_leases.h ***/ /*** static_leases.h ***/

12
networking/udhcp/leases.c
View File

@ -118,7 +118,7 @@ struct dhcpOfferedAddr* FAST_FUNC find_lease_by_yiaddr(uint32_t yiaddr)
/* check is an IP is taken, if it is, add it to the lease table */ /* check is an IP is taken, if it is, add it to the lease table */
static int nobody_responds_to_arp(uint32_t addr) static int nobody_responds_to_arp(uint32_t addr, const uint8_t *safe_mac)
{ {
/* 16 zero bytes */ /* 16 zero bytes */
static const uint8_t blank_chaddr[16] = { 0 }; static const uint8_t blank_chaddr[16] = { 0 };
@ -127,7 +127,9 @@ static int nobody_responds_to_arp(uint32_t addr)
struct in_addr temp; struct in_addr temp;
int r; int r;
r = arpping(addr, server_config.server, server_config.arp, server_config.interface); r = arpping(addr, safe_mac,
server_config.server, server_config.arp,
server_config.interface);
if (r) if (r)
return r; return r;
@ -140,7 +142,7 @@ static int nobody_responds_to_arp(uint32_t addr)
/* Find a new usable (we think) address. */ /* Find a new usable (we think) address. */
uint32_t FAST_FUNC find_free_or_expired_address(void) uint32_t FAST_FUNC find_free_or_expired_address(const uint8_t *chaddr)
{ {
uint32_t addr; uint32_t addr;
struct dhcpOfferedAddr *oldest_lease = NULL; struct dhcpOfferedAddr *oldest_lease = NULL;
@ -163,7 +165,7 @@ uint32_t FAST_FUNC find_free_or_expired_address(void)
lease = find_lease_by_yiaddr(net_addr); lease = find_lease_by_yiaddr(net_addr);
if (!lease) { if (!lease) {
if (nobody_responds_to_arp(net_addr)) if (nobody_responds_to_arp(net_addr, chaddr))
return net_addr; return net_addr;
} else { } else {
if (!oldest_lease || lease->expires < oldest_lease->expires) if (!oldest_lease || lease->expires < oldest_lease->expires)
@ -172,7 +174,7 @@ uint32_t FAST_FUNC find_free_or_expired_address(void)
} }
if (oldest_lease && lease_expired(oldest_lease) if (oldest_lease && lease_expired(oldest_lease)
&& nobody_responds_to_arp(oldest_lease->yiaddr) && nobody_responds_to_arp(oldest_lease->yiaddr, chaddr)
) { ) {
return oldest_lease->yiaddr; return oldest_lease->yiaddr;
} }

53
networking/udhcp/serverpacket.c
View File

@ -31,7 +31,8 @@ static int send_packet_to_relay(struct dhcpMessage *payload)
{ {
DEBUG("Forwarding packet to relay"); DEBUG("Forwarding packet to relay");
return udhcp_send_kernel_packet(payload, server_config.server, SERVER_PORT, return udhcp_send_kernel_packet(payload,
server_config.server, SERVER_PORT,
payload->giaddr, SERVER_PORT); payload->giaddr, SERVER_PORT);
} }
@ -42,23 +43,31 @@ static int send_packet_to_client(struct dhcpMessage *payload, int force_broadcas
const uint8_t *chaddr; const uint8_t *chaddr;
uint32_t ciaddr; uint32_t ciaddr;
if (force_broadcast) { // Was:
DEBUG("broadcasting packet to client (NAK)"); //if (force_broadcast) { /* broadcast */ }
ciaddr = INADDR_BROADCAST; //else if (payload->ciaddr) { /* unicast to payload->ciaddr */ }
chaddr = MAC_BCAST_ADDR; //else if (payload->flags & htons(BROADCAST_FLAG)) { /* broadcast */ }
} else if (payload->ciaddr) { //else { /* unicast to payload->yiaddr */ }
DEBUG("unicasting packet to client ciaddr"); // But this is wrong: yiaddr is _our_ idea what client's IP is
ciaddr = payload->ciaddr; // (for example, from lease file). Client may not know that,
chaddr = payload->chaddr; // and may not have UDP socket listening on that IP!
} else if (payload->flags & htons(BROADCAST_FLAG)) { // We should never unicast to payload->yiaddr!
DEBUG("broadcasting packet to client (requested)"); // payload->ciaddr, OTOH, comes from client's request packet,
// and can be used.
if (force_broadcast
|| (payload->flags & htons(BROADCAST_FLAG))
|| !payload->ciaddr
) {
DEBUG("broadcasting packet to client");
ciaddr = INADDR_BROADCAST; ciaddr = INADDR_BROADCAST;
chaddr = MAC_BCAST_ADDR; chaddr = MAC_BCAST_ADDR;
} else { } else {
DEBUG("unicasting packet to client yiaddr"); DEBUG("unicasting packet to client ciaddr");
ciaddr = payload->yiaddr; ciaddr = payload->ciaddr;
chaddr = payload->chaddr; chaddr = payload->chaddr;
} }
return udhcp_send_raw_packet(payload, return udhcp_send_raw_packet(payload,
/*src*/ server_config.server, SERVER_PORT, /*src*/ server_config.server, SERVER_PORT,
/*dst*/ ciaddr, CLIENT_PORT, chaddr, /*dst*/ ciaddr, CLIENT_PORT, chaddr,
@ -118,17 +127,18 @@ int FAST_FUNC send_offer(struct dhcpMessage *oldpacket)
struct dhcpOfferedAddr *lease; struct dhcpOfferedAddr *lease;
lease = find_lease_by_chaddr(oldpacket->chaddr); lease = find_lease_by_chaddr(oldpacket->chaddr);
/* the client is in our lease/offered table */ /* The client is in our lease/offered table */
if (lease) { if (lease) {
signed_leasetime_t tmp = lease->expires - time(NULL); signed_leasetime_t tmp = lease->expires - time(NULL);
if (tmp >= 0) if (tmp >= 0)
lease_time_aligned = tmp; lease_time_aligned = tmp;
packet.yiaddr = lease->yiaddr; packet.yiaddr = lease->yiaddr;
/* Or the client has requested an ip */ }
} else if ((req = get_option(oldpacket, DHCP_REQUESTED_IP)) != NULL /* Or the client has requested an IP */
/* Don't look here (ugly hackish thing to do) */ else if ((req = get_option(oldpacket, DHCP_REQUESTED_IP)) != NULL
/* (read IP) */
&& (move_from_unaligned32(req_align, req), 1) && (move_from_unaligned32(req_align, req), 1)
/* and the ip is in the lease range */ /* and the IP is in the lease range */
&& ntohl(req_align) >= server_config.start_ip && ntohl(req_align) >= server_config.start_ip
&& ntohl(req_align) <= server_config.end_ip && ntohl(req_align) <= server_config.end_ip
/* and is not already taken/offered */ /* and is not already taken/offered */
@ -137,9 +147,10 @@ int FAST_FUNC send_offer(struct dhcpMessage *oldpacket)
|| lease_expired(lease)) || lease_expired(lease))
) { ) {
packet.yiaddr = req_align; packet.yiaddr = req_align;
/* otherwise, find a free IP */ }
} else { /* Otherwise, find a free IP */
packet.yiaddr = find_free_or_expired_address(); else {
packet.yiaddr = find_free_or_expired_address(oldpacket->chaddr);
} }
if (!packet.yiaddr) { if (!packet.yiaddr) {