return 0;
}
+char *dhcpv4_msg_to_string(uint8_t reqmsg)
+{
+ switch (reqmsg) {
+ case (DHCPV4_MSG_DISCOVER):
+ return "DHCPV4_MSG_DISCOVER";
+ case (DHCPV4_MSG_OFFER):
+ return "DHCPV4_MSG_OFFER";
+ case (DHCPV4_MSG_REQUEST):
+ return "DHCPV4_MSG_REQUEST";
+ case (DHCPV4_MSG_DECLINE):
+ return "DHCPV4_MSG_DECLINE";
+ case (DHCPV4_MSG_ACK):
+ return "DHCPV4_MSG_ACK";
+ case (DHCPV4_MSG_NAK):
+ return "DHCPV4_MSG_NAK";
+ case (DHCPV4_MSG_RELEASE):
+ return "DHCPV4_MSG_RELEASE";
+ case (DHCPV4_MSG_INFORM):
+ return "DHCPV4_MSG_INFORM";
+ default:
+ return "UNKNOWN";
+ }
+}
int setup_dhcpv4_interface(struct interface *iface, bool enable)
{
if (start && end && start < end &&
start > ntohl(addr.s_addr & ~mask.s_addr) &&
- (start & ntohl(mask.s_addr)) == start &&
- (end & ntohl(mask.s_addr)) == end) {
+ (start & ntohl(~mask.s_addr)) == start &&
+ (end & ntohl(~mask.s_addr)) == end) {
iface->dhcpv4_start.s_addr = htonl(start) |
(addr.s_addr & mask.s_addr);
iface->dhcpv4_end.s_addr = htonl(end) |
struct dhcpv4_assignment *a = list_first_entry(&iface->dhcpv4_assignments,
struct dhcpv4_assignment, head);
list_del(&a->head);
- free(a->hostname);
free(a);
}
} else if (reqmsg == DHCPV4_MSG_REQUEST && reqaddr.s_addr &&
reqaddr.s_addr != htonl(lease->addr)) {
msg = DHCPV4_MSG_NAK;
- lease = NULL;
+ /*
+ * DHCP client requested an IP which we can't offer to him. Probably the
+ * client changed the network. The reply type is set to DHCPV4_MSG_NAK,
+ * because the client should not use that IP.
+ *
+ * For modern devices we build an answer that includes a valid IP, like
+ * a DHCPV4_MSG_ACK. The client will use that IP and doesn't need to
+ * perform additional DHCP round trips.
+ *
+ */
}
+ syslog(LOG_WARNING, "received %s from %x:%x:%x:%x:%x:%x",
+ dhcpv4_msg_to_string(reqmsg),
+ req->chaddr[0],req->chaddr[1],req->chaddr[2],
+ req->chaddr[3],req->chaddr[4],req->chaddr[5]);
+
if (reqmsg == DHCPV4_MSG_DECLINE || reqmsg == DHCPV4_MSG_RELEASE)
return;
len, search_buf);
}
- dhcpv4_put(&reply, &cookie, DHCPV4_OPT_ROUTER, 4, &ifaddr.sin_addr);
-
+ if (iface->dhcpv4_router_cnt == 0)
+ dhcpv4_put(&reply, &cookie, DHCPV4_OPT_ROUTER, 4, &ifaddr.sin_addr);
+ else
+ dhcpv4_put(&reply, &cookie, DHCPV4_OPT_ROUTER,
+ 4 * iface->dhcpv4_router_cnt, iface->dhcpv4_router);
if (iface->dhcpv4_dns_cnt == 0)
struct sockaddr_in dest = *((struct sockaddr_in*)addr);
if (req->giaddr.s_addr) {
+ /*
+ * relay agent is configured, send reply to the agent
+ */
dest.sin_addr = req->giaddr;
dest.sin_port = htons(DHCPV4_SERVER_PORT);
} else if (req->ciaddr.s_addr && req->ciaddr.s_addr != dest.sin_addr.s_addr) {
+ /*
+ * client has existing configuration (ciaddr is set) AND this address is
+ * not the address it used for the dhcp message
+ */
dest.sin_addr = req->ciaddr;
dest.sin_port = htons(DHCPV4_CLIENT_PORT);
} else if ((ntohs(req->flags) & DHCPV4_FLAG_BROADCAST) ||
req->hlen != reply.hlen || !reply.yiaddr.s_addr) {
+ /*
+ * client requests a broadcast reply OR we can't offer an IP
+ */
+ dest.sin_addr.s_addr = INADDR_BROADCAST;
+ dest.sin_port = htons(DHCPV4_CLIENT_PORT);
+ } else if (!req->ciaddr.s_addr && msg == DHCPV4_MSG_NAK) {
+ /*
+ * client has no previous configuration -> no IP, so we need to reply
+ * with a broadcast packet
+ */
dest.sin_addr.s_addr = INADDR_BROADCAST;
dest.sin_port = htons(DHCPV4_CLIENT_PORT);
} else {
+ /*
+ * send reply to the newly (in this proccess) allocated IP
+ */
dest.sin_addr = reply.yiaddr;
dest.sin_port = htons(DHCPV4_CLIENT_PORT);
ioctl(sock, SIOCSARP, &arp);
}
+ if (dest.sin_addr.s_addr == INADDR_BROADCAST) {
+ /*
+ * reply goes to IP broadcast -> MAC broadcast
+ */
+ syslog(LOG_WARNING, "sending %s to ff:ff:ff:ff:ff:ff - %s",
+ dhcpv4_msg_to_string(msg),
+ inet_ntoa(dest.sin_addr));
+ } else {
+ /*
+ * reply is send directly to IP,
+ * MAC is assumed to be the same as the request
+ */
+ syslog(LOG_WARNING, "sending %s to %x:%x:%x:%x:%x:%x - %s",
+ dhcpv4_msg_to_string(msg),
+ req->chaddr[0],req->chaddr[1],req->chaddr[2],
+ req->chaddr[3],req->chaddr[4],req->chaddr[5],
+ inet_ntoa(dest.sin_addr));
+ }
+
sendto(sock, &reply, sizeof(reply), MSG_DONTWAIT,
(struct sockaddr*)&dest, sizeof(dest));
}
+static bool dhcpv4_test(struct interface *iface, uint32_t try)
+{
+ struct dhcpv4_assignment *c;
+ list_for_each_entry(c, &iface->dhcpv4_assignments, head) {
+ if (c->addr == try) {
+ return false;
+ }
+ }
+ return true;
+}
static bool dhcpv4_assign(struct interface *iface,
struct dhcpv4_assignment *assign, uint32_t raddr)
{
- const unsigned tries = 10;
uint32_t start = ntohl(iface->dhcpv4_start.s_addr);
uint32_t end = ntohl(iface->dhcpv4_end.s_addr);
uint32_t count = end - start + 1;
- // Seed RNG with checksum of DUID
+ // try to assign the IP the client asked for
+ if (start <= raddr && raddr <= end && dhcpv4_test(iface, raddr)) {
+ assign->addr = raddr;
+ list_add(&assign->head, &iface->dhcpv4_assignments);
+ syslog(LOG_DEBUG, "assigning the IP the client asked for: %u.%u.%u.%u",
+ (assign->addr & 0xff000000) >> 24,
+ (assign->addr & 0x00ff0000) >> 16,
+ (assign->addr & 0x0000ff00) >> 8,
+ (assign->addr & 0x000000ff));
+ return true;
+ }
+
+ // Seed RNG with checksum of hwaddress
uint32_t seed = 0;
- for (size_t i = 0; i < sizeof(assign->hwaddr); ++i)
- seed += assign->hwaddr[i];
+ for (size_t i = 0; i < sizeof(assign->hwaddr); ++i) {
+ // Knuth's multiplicative method
+ uint8_t o = assign->hwaddr[i];
+ seed += (o*2654435761) % UINT32_MAX;
+ }
srand(seed);
- // Try to assign up to 100x
- for (unsigned i = 0; i < tries; ++i) {
- uint32_t try = (((uint32_t)rand()) % count) + start;
- if (i == 0 && raddr >= start && raddr <= end)
- try = raddr;
- else if (i == tries - 1)
- try = start;
+ uint32_t try = (((uint32_t)rand()) % count) + start;
+
+ if (list_empty(&iface->dhcpv4_assignments)) {
+ assign->addr = try;
+ list_add(&assign->head, &iface->dhcpv4_assignments);
+ syslog(LOG_DEBUG, "assigning mapped IP (empty list): %u.%u.%u.%u",
+ (assign->addr & 0xff000000) >> 24,
+ (assign->addr & 0x00ff0000) >> 16,
+ (assign->addr & 0x0000ff00) >> 8,
+ (assign->addr & 0x000000ff));
+ return true;
+ }
- if (list_empty(&iface->dhcpv4_assignments)) {
+ for (uint32_t i = 0; i < count; ++i) {
+ if (dhcpv4_test(iface, try)) {
+ /* test was successful: IP address is not assigned, assign it */
assign->addr = try;
list_add(&assign->head, &iface->dhcpv4_assignments);
+ syslog(LOG_DEBUG, "assigning mapped IP: %u.%u.%u.%u (try %u of %u)",
+ (assign->addr & 0xff000000) >> 24,
+ (assign->addr & 0x00ff0000) >> 16,
+ (assign->addr & 0x0000ff00) >> 8,
+ (assign->addr & 0x000000ff), i, count);
return true;
}
-
- struct dhcpv4_assignment *c;
- list_for_each_entry(c, &iface->dhcpv4_assignments, head) {
- if (c->addr > try) {
- assign->addr = try;
- list_add_tail(&assign->head, &c->head);
- return true;
- } else if (c->addr == try) {
- if (i < tries - 1)
- break;
- else
- ++try;
- }
- }
+ try = (((try - start) + 1) % count) + start;
}
+ syslog(LOG_DEBUG, "can't assign any IP address -> address space is full");
return false;
}
if (assigned && a)
lease = a;
} else if (msg == DHCPV4_MSG_RELEASE) {
- if (a) {
+ if (a && a->valid_until != LONG_MAX)
a->valid_until = 0;
- }
- } else if (msg == DHCPV4_MSG_DECLINE) {
+ } else if (msg == DHCPV4_MSG_DECLINE && a && a->valid_until != LONG_MAX) {
memset(a->hwaddr, 0, sizeof(a->hwaddr));
a->valid_until = now + 3600; // Block address for 1h
}
projects / project / odhcpd.git / blobdiff