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-rw-r--r--src/libsystemd-network/sd-dhcp-server.c1222
1 files changed, 1222 insertions, 0 deletions
diff --git a/src/libsystemd-network/sd-dhcp-server.c b/src/libsystemd-network/sd-dhcp-server.c
new file mode 100644
index 0000000..dfced72
--- /dev/null
+++ b/src/libsystemd-network/sd-dhcp-server.c
@@ -0,0 +1,1222 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/***
+ Copyright © 2013 Intel Corporation. All rights reserved.
+***/
+
+#include <net/if_arp.h>
+#include <sys/ioctl.h>
+
+#include "sd-dhcp-server.h"
+#include "sd-id128.h"
+
+#include "alloc-util.h"
+#include "dhcp-internal.h"
+#include "dhcp-server-internal.h"
+#include "fd-util.h"
+#include "in-addr-util.h"
+#include "io-util.h"
+#include "siphash24.h"
+#include "string-util.h"
+#include "unaligned.h"
+
+#define DHCP_DEFAULT_LEASE_TIME_USEC USEC_PER_HOUR
+#define DHCP_MAX_LEASE_TIME_USEC (USEC_PER_HOUR*12)
+
+static DHCPLease *dhcp_lease_free(DHCPLease *lease) {
+ if (!lease)
+ return NULL;
+
+ free(lease->client_id.data);
+ return mfree(lease);
+}
+
+/* configures the server's address and subnet, and optionally the pool's size and offset into the subnet
+ * the whole pool must fit into the subnet, and may not contain the first (any) nor last (broadcast) address
+ * moreover, the server's own address may be in the pool, and is in that case reserved in order not to
+ * accidentally hand it out */
+int sd_dhcp_server_configure_pool(
+ sd_dhcp_server *server,
+ const struct in_addr *address,
+ unsigned char prefixlen,
+ uint32_t offset,
+ uint32_t size) {
+
+ struct in_addr netmask_addr;
+ be32_t netmask;
+ uint32_t server_off, broadcast_off, size_max;
+
+ assert_return(server, -EINVAL);
+ assert_return(address, -EINVAL);
+ assert_return(address->s_addr != INADDR_ANY, -EINVAL);
+ assert_return(prefixlen <= 32, -ERANGE);
+
+ assert_se(in4_addr_prefixlen_to_netmask(&netmask_addr, prefixlen));
+ netmask = netmask_addr.s_addr;
+
+ server_off = be32toh(address->s_addr & ~netmask);
+ broadcast_off = be32toh(~netmask);
+
+ /* the server address cannot be the subnet address */
+ assert_return(server_off != 0, -ERANGE);
+
+ /* nor the broadcast address */
+ assert_return(server_off != broadcast_off, -ERANGE);
+
+ /* 0 offset means we should set a default, we skip the first (subnet) address
+ and take the next one */
+ if (offset == 0)
+ offset = 1;
+
+ size_max = (broadcast_off + 1) /* the number of addresses in the subnet */
+ - offset /* exclude the addresses before the offset */
+ - 1; /* exclude the last (broadcast) address */
+
+ /* The pool must contain at least one address */
+ assert_return(size_max >= 1, -ERANGE);
+
+ if (size != 0)
+ assert_return(size <= size_max, -ERANGE);
+ else
+ size = size_max;
+
+ if (server->address != address->s_addr || server->netmask != netmask || server->pool_size != size || server->pool_offset != offset) {
+
+ free(server->bound_leases);
+ server->bound_leases = new0(DHCPLease*, size);
+ if (!server->bound_leases)
+ return -ENOMEM;
+
+ server->pool_offset = offset;
+ server->pool_size = size;
+
+ server->address = address->s_addr;
+ server->netmask = netmask;
+ server->subnet = address->s_addr & netmask;
+
+ if (server_off >= offset && server_off - offset < size)
+ server->bound_leases[server_off - offset] = &server->invalid_lease;
+
+ /* Drop any leases associated with the old address range */
+ hashmap_clear(server->leases_by_client_id);
+
+ if (server->callback)
+ server->callback(server, SD_DHCP_SERVER_EVENT_LEASE_CHANGED, server->callback_userdata);
+ }
+
+ return 0;
+}
+
+int sd_dhcp_server_is_running(sd_dhcp_server *server) {
+ assert_return(server, false);
+
+ return !!server->receive_message;
+}
+
+void client_id_hash_func(const DHCPClientId *id, struct siphash *state) {
+ assert(id);
+ assert(id->length);
+ assert(id->data);
+
+ siphash24_compress(&id->length, sizeof(id->length), state);
+ siphash24_compress(id->data, id->length, state);
+}
+
+int client_id_compare_func(const DHCPClientId *a, const DHCPClientId *b) {
+ int r;
+
+ assert(!a->length || a->data);
+ assert(!b->length || b->data);
+
+ r = CMP(a->length, b->length);
+ if (r != 0)
+ return r;
+
+ return memcmp(a->data, b->data, a->length);
+}
+
+DEFINE_PRIVATE_HASH_OPS_WITH_VALUE_DESTRUCTOR(dhcp_lease_hash_ops, DHCPClientId, client_id_hash_func, client_id_compare_func,
+ DHCPLease, dhcp_lease_free);
+
+static sd_dhcp_server *dhcp_server_free(sd_dhcp_server *server) {
+ assert(server);
+
+ log_dhcp_server(server, "UNREF");
+
+ sd_dhcp_server_stop(server);
+
+ sd_event_unref(server->event);
+
+ free(server->timezone);
+
+ for (sd_dhcp_lease_server_type i = 0; i < _SD_DHCP_LEASE_SERVER_TYPE_MAX; i++)
+ free(server->servers[i].addr);
+
+ hashmap_free(server->leases_by_client_id);
+
+ ordered_hashmap_free(server->extra_options);
+ ordered_hashmap_free(server->vendor_options);
+
+ free(server->bound_leases);
+ return mfree(server);
+}
+
+DEFINE_TRIVIAL_REF_UNREF_FUNC(sd_dhcp_server, sd_dhcp_server, dhcp_server_free);
+
+int sd_dhcp_server_new(sd_dhcp_server **ret, int ifindex) {
+ _cleanup_(sd_dhcp_server_unrefp) sd_dhcp_server *server = NULL;
+
+ assert_return(ret, -EINVAL);
+ assert_return(ifindex > 0, -EINVAL);
+
+ server = new0(sd_dhcp_server, 1);
+ if (!server)
+ return -ENOMEM;
+
+ server->n_ref = 1;
+ server->fd_raw = -1;
+ server->fd = -1;
+ server->address = htobe32(INADDR_ANY);
+ server->netmask = htobe32(INADDR_ANY);
+ server->ifindex = ifindex;
+
+ server->leases_by_client_id = hashmap_new(&dhcp_lease_hash_ops);
+ if (!server->leases_by_client_id)
+ return -ENOMEM;
+
+ server->default_lease_time = DIV_ROUND_UP(DHCP_DEFAULT_LEASE_TIME_USEC, USEC_PER_SEC);
+ server->max_lease_time = DIV_ROUND_UP(DHCP_MAX_LEASE_TIME_USEC, USEC_PER_SEC);
+
+ *ret = TAKE_PTR(server);
+
+ return 0;
+}
+
+int sd_dhcp_server_attach_event(sd_dhcp_server *server, sd_event *event, int64_t priority) {
+ int r;
+
+ assert_return(server, -EINVAL);
+ assert_return(!server->event, -EBUSY);
+
+ if (event)
+ server->event = sd_event_ref(event);
+ else {
+ r = sd_event_default(&server->event);
+ if (r < 0)
+ return r;
+ }
+
+ server->event_priority = priority;
+
+ return 0;
+}
+
+int sd_dhcp_server_detach_event(sd_dhcp_server *server) {
+ assert_return(server, -EINVAL);
+
+ server->event = sd_event_unref(server->event);
+
+ return 0;
+}
+
+sd_event *sd_dhcp_server_get_event(sd_dhcp_server *server) {
+ assert_return(server, NULL);
+
+ return server->event;
+}
+
+int sd_dhcp_server_stop(sd_dhcp_server *server) {
+ if (!server)
+ return 0;
+
+ server->receive_message =
+ sd_event_source_unref(server->receive_message);
+
+ server->fd_raw = safe_close(server->fd_raw);
+ server->fd = safe_close(server->fd);
+
+ log_dhcp_server(server, "STOPPED");
+
+ return 0;
+}
+
+static int dhcp_server_send_unicast_raw(sd_dhcp_server *server,
+ DHCPPacket *packet, size_t len) {
+ union sockaddr_union link = {
+ .ll.sll_family = AF_PACKET,
+ .ll.sll_protocol = htobe16(ETH_P_IP),
+ .ll.sll_ifindex = server->ifindex,
+ .ll.sll_halen = ETH_ALEN,
+ };
+
+ assert(server);
+ assert(server->ifindex > 0);
+ assert(server->address);
+ assert(packet);
+ assert(len > sizeof(DHCPPacket));
+
+ memcpy(&link.ll.sll_addr, &packet->dhcp.chaddr, ETH_ALEN);
+
+ dhcp_packet_append_ip_headers(packet, server->address, DHCP_PORT_SERVER,
+ packet->dhcp.yiaddr,
+ DHCP_PORT_CLIENT, len, -1);
+
+ return dhcp_network_send_raw_socket(server->fd_raw, &link, packet, len);
+}
+
+static int dhcp_server_send_udp(sd_dhcp_server *server, be32_t destination,
+ uint16_t destination_port,
+ DHCPMessage *message, size_t len) {
+ union sockaddr_union dest = {
+ .in.sin_family = AF_INET,
+ .in.sin_port = htobe16(destination_port),
+ .in.sin_addr.s_addr = destination,
+ };
+ struct iovec iov = {
+ .iov_base = message,
+ .iov_len = len,
+ };
+ CMSG_BUFFER_TYPE(CMSG_SPACE(sizeof(struct in_pktinfo))) control = {};
+ struct msghdr msg = {
+ .msg_name = &dest,
+ .msg_namelen = sizeof(dest.in),
+ .msg_iov = &iov,
+ .msg_iovlen = 1,
+ .msg_control = &control,
+ .msg_controllen = sizeof(control),
+ };
+ struct cmsghdr *cmsg;
+ struct in_pktinfo *pktinfo;
+
+ assert(server);
+ assert(server->fd >= 0);
+ assert(message);
+ assert(len > sizeof(DHCPMessage));
+
+ cmsg = CMSG_FIRSTHDR(&msg);
+ assert(cmsg);
+
+ cmsg->cmsg_level = IPPROTO_IP;
+ cmsg->cmsg_type = IP_PKTINFO;
+ cmsg->cmsg_len = CMSG_LEN(sizeof(struct in_pktinfo));
+
+ /* we attach source interface and address info to the message
+ rather than binding the socket. This will be mostly useful
+ when we gain support for arbitrary number of server addresses
+ */
+ pktinfo = (struct in_pktinfo*) CMSG_DATA(cmsg);
+ assert(pktinfo);
+
+ pktinfo->ipi_ifindex = server->ifindex;
+ pktinfo->ipi_spec_dst.s_addr = server->address;
+
+ if (sendmsg(server->fd, &msg, 0) < 0)
+ return -errno;
+
+ return 0;
+}
+
+static bool requested_broadcast(DHCPRequest *req) {
+ assert(req);
+
+ return req->message->flags & htobe16(0x8000);
+}
+
+int dhcp_server_send_packet(sd_dhcp_server *server,
+ DHCPRequest *req, DHCPPacket *packet,
+ int type, size_t optoffset) {
+ be32_t destination = INADDR_ANY;
+ uint16_t destination_port = DHCP_PORT_CLIENT;
+ int r;
+
+ assert(server);
+ assert(req);
+ assert(req->max_optlen);
+ assert(optoffset <= req->max_optlen);
+ assert(packet);
+
+ r = dhcp_option_append(&packet->dhcp, req->max_optlen, &optoffset, 0,
+ SD_DHCP_OPTION_SERVER_IDENTIFIER,
+ 4, &server->address);
+ if (r < 0)
+ return r;
+
+ r = dhcp_option_append(&packet->dhcp, req->max_optlen, &optoffset, 0,
+ SD_DHCP_OPTION_END, 0, NULL);
+ if (r < 0)
+ return r;
+
+ /* RFC 2131 Section 4.1
+
+ If the ’giaddr’ field in a DHCP message from a client is non-zero,
+ the server sends any return messages to the ’DHCP server’ port on the
+ BOOTP relay agent whose address appears in ’giaddr’. If the ’giaddr’
+ field is zero and the ’ciaddr’ field is nonzero, then the server
+ unicasts DHCPOFFER and DHCPACK messages to the address in ’ciaddr’.
+ If ’giaddr’ is zero and ’ciaddr’ is zero, and the broadcast bit is
+ set, then the server broadcasts DHCPOFFER and DHCPACK messages to
+ 0xffffffff. If the broadcast bit is not set and ’giaddr’ is zero and
+ ’ciaddr’ is zero, then the server unicasts DHCPOFFER and DHCPACK
+ messages to the client’s hardware address and ’yiaddr’ address. In
+ all cases, when ’giaddr’ is zero, the server broadcasts any DHCPNAK
+ messages to 0xffffffff.
+
+ Section 4.3.2
+
+ If ’giaddr’ is set in the DHCPREQUEST message, the client is on a
+ different subnet. The server MUST set the broadcast bit in the
+ DHCPNAK, so that the relay agent will broadcast the DHCPNAK to the
+ client, because the client may not have a correct network address
+ or subnet mask, and the client may not be answering ARP requests.
+ */
+ if (req->message->giaddr) {
+ destination = req->message->giaddr;
+ destination_port = DHCP_PORT_SERVER;
+ if (type == DHCP_NAK)
+ packet->dhcp.flags = htobe16(0x8000);
+ } else if (req->message->ciaddr && type != DHCP_NAK)
+ destination = req->message->ciaddr;
+
+ if (destination != INADDR_ANY)
+ return dhcp_server_send_udp(server, destination,
+ destination_port, &packet->dhcp,
+ sizeof(DHCPMessage) + optoffset);
+ else if (requested_broadcast(req) || type == DHCP_NAK)
+ return dhcp_server_send_udp(server, INADDR_BROADCAST,
+ destination_port, &packet->dhcp,
+ sizeof(DHCPMessage) + optoffset);
+ else
+ /* we cannot send UDP packet to specific MAC address when the
+ address is not yet configured, so must fall back to raw
+ packets */
+ return dhcp_server_send_unicast_raw(server, packet,
+ sizeof(DHCPPacket) + optoffset);
+}
+
+static int server_message_init(sd_dhcp_server *server, DHCPPacket **ret,
+ uint8_t type, size_t *_optoffset,
+ DHCPRequest *req) {
+ _cleanup_free_ DHCPPacket *packet = NULL;
+ size_t optoffset = 0;
+ int r;
+
+ assert(server);
+ assert(ret);
+ assert(_optoffset);
+ assert(IN_SET(type, DHCP_OFFER, DHCP_ACK, DHCP_NAK));
+
+ packet = malloc0(sizeof(DHCPPacket) + req->max_optlen);
+ if (!packet)
+ return -ENOMEM;
+
+ r = dhcp_message_init(&packet->dhcp, BOOTREPLY,
+ be32toh(req->message->xid), type, ARPHRD_ETHER,
+ req->max_optlen, &optoffset);
+ if (r < 0)
+ return r;
+
+ packet->dhcp.flags = req->message->flags;
+ packet->dhcp.giaddr = req->message->giaddr;
+ memcpy(&packet->dhcp.chaddr, &req->message->chaddr, ETH_ALEN);
+
+ *_optoffset = optoffset;
+ *ret = TAKE_PTR(packet);
+
+ return 0;
+}
+
+static int server_send_offer(sd_dhcp_server *server, DHCPRequest *req,
+ be32_t address) {
+ _cleanup_free_ DHCPPacket *packet = NULL;
+ size_t offset;
+ be32_t lease_time;
+ int r;
+
+ r = server_message_init(server, &packet, DHCP_OFFER, &offset, req);
+ if (r < 0)
+ return r;
+
+ packet->dhcp.yiaddr = address;
+
+ lease_time = htobe32(req->lifetime);
+ r = dhcp_option_append(&packet->dhcp, req->max_optlen, &offset, 0,
+ SD_DHCP_OPTION_IP_ADDRESS_LEASE_TIME, 4,
+ &lease_time);
+ if (r < 0)
+ return r;
+
+ r = dhcp_option_append(&packet->dhcp, req->max_optlen, &offset, 0,
+ SD_DHCP_OPTION_SUBNET_MASK, 4, &server->netmask);
+ if (r < 0)
+ return r;
+
+ if (server->emit_router) {
+ r = dhcp_option_append(&packet->dhcp, req->max_optlen, &offset, 0,
+ SD_DHCP_OPTION_ROUTER, 4, &server->address);
+ if (r < 0)
+ return r;
+ }
+
+ r = dhcp_server_send_packet(server, req, packet, DHCP_OFFER, offset);
+ if (r < 0)
+ return r;
+
+ return 0;
+}
+
+static int server_send_ack(
+ sd_dhcp_server *server,
+ DHCPRequest *req,
+ be32_t address) {
+
+ static const uint8_t option_map[_SD_DHCP_LEASE_SERVER_TYPE_MAX] = {
+ [SD_DHCP_LEASE_DNS] = SD_DHCP_OPTION_DOMAIN_NAME_SERVER,
+ [SD_DHCP_LEASE_NTP] = SD_DHCP_OPTION_NTP_SERVER,
+ [SD_DHCP_LEASE_SIP] = SD_DHCP_OPTION_SIP_SERVER,
+ [SD_DHCP_LEASE_POP3] = SD_DHCP_OPTION_POP3_SERVER,
+ [SD_DHCP_LEASE_SMTP] = SD_DHCP_OPTION_SMTP_SERVER,
+ [SD_DHCP_LEASE_LPR] = SD_DHCP_OPTION_LPR_SERVER,
+ };
+
+ _cleanup_free_ DHCPPacket *packet = NULL;
+ be32_t lease_time;
+ sd_dhcp_option *j;
+ size_t offset;
+ int r;
+
+ r = server_message_init(server, &packet, DHCP_ACK, &offset, req);
+ if (r < 0)
+ return r;
+
+ packet->dhcp.yiaddr = address;
+
+ lease_time = htobe32(req->lifetime);
+ r = dhcp_option_append(&packet->dhcp, req->max_optlen, &offset, 0,
+ SD_DHCP_OPTION_IP_ADDRESS_LEASE_TIME, 4,
+ &lease_time);
+ if (r < 0)
+ return r;
+
+ r = dhcp_option_append(&packet->dhcp, req->max_optlen, &offset, 0,
+ SD_DHCP_OPTION_SUBNET_MASK, 4, &server->netmask);
+ if (r < 0)
+ return r;
+
+ if (server->emit_router) {
+ r = dhcp_option_append(&packet->dhcp, req->max_optlen, &offset, 0,
+ SD_DHCP_OPTION_ROUTER, 4, &server->address);
+ if (r < 0)
+ return r;
+ }
+
+ for (sd_dhcp_lease_server_type k = 0; k < _SD_DHCP_LEASE_SERVER_TYPE_MAX; k++) {
+
+ if (server->servers[k].size <= 0)
+ continue;
+
+ r = dhcp_option_append(
+ &packet->dhcp, req->max_optlen, &offset, 0,
+ option_map[k],
+ sizeof(struct in_addr) * server->servers[k].size, server->servers[k].addr);
+ if (r < 0)
+ return r;
+ }
+
+
+ if (server->timezone) {
+ r = dhcp_option_append(
+ &packet->dhcp, req->max_optlen, &offset, 0,
+ SD_DHCP_OPTION_NEW_TZDB_TIMEZONE,
+ strlen(server->timezone), server->timezone);
+ if (r < 0)
+ return r;
+ }
+
+ ORDERED_HASHMAP_FOREACH(j, server->extra_options) {
+ r = dhcp_option_append(&packet->dhcp, req->max_optlen, &offset, 0,
+ j->option, j->length, j->data);
+ if (r < 0)
+ return r;
+ }
+
+ if (!ordered_hashmap_isempty(server->vendor_options)) {
+ r = dhcp_option_append(
+ &packet->dhcp, req->max_optlen, &offset, 0,
+ SD_DHCP_OPTION_VENDOR_SPECIFIC,
+ ordered_hashmap_size(server->vendor_options), server->vendor_options);
+ if (r < 0)
+ return r;
+ }
+
+ r = dhcp_server_send_packet(server, req, packet, DHCP_ACK, offset);
+ if (r < 0)
+ return r;
+
+ return 0;
+}
+
+static int server_send_nak(sd_dhcp_server *server, DHCPRequest *req) {
+ _cleanup_free_ DHCPPacket *packet = NULL;
+ size_t offset;
+ int r;
+
+ r = server_message_init(server, &packet, DHCP_NAK, &offset, req);
+ if (r < 0)
+ return r;
+
+ return dhcp_server_send_packet(server, req, packet, DHCP_NAK, offset);
+}
+
+static int server_send_forcerenew(sd_dhcp_server *server, be32_t address,
+ be32_t gateway, const uint8_t chaddr[]) {
+ _cleanup_free_ DHCPPacket *packet = NULL;
+ size_t optoffset = 0;
+ int r;
+
+ assert(server);
+ assert(address != INADDR_ANY);
+ assert(chaddr);
+
+ packet = malloc0(sizeof(DHCPPacket) + DHCP_MIN_OPTIONS_SIZE);
+ if (!packet)
+ return -ENOMEM;
+
+ r = dhcp_message_init(&packet->dhcp, BOOTREPLY, 0,
+ DHCP_FORCERENEW, ARPHRD_ETHER,
+ DHCP_MIN_OPTIONS_SIZE, &optoffset);
+ if (r < 0)
+ return r;
+
+ r = dhcp_option_append(&packet->dhcp, DHCP_MIN_OPTIONS_SIZE,
+ &optoffset, 0, SD_DHCP_OPTION_END, 0, NULL);
+ if (r < 0)
+ return r;
+
+ memcpy(&packet->dhcp.chaddr, chaddr, ETH_ALEN);
+
+ r = dhcp_server_send_udp(server, address, DHCP_PORT_CLIENT,
+ &packet->dhcp,
+ sizeof(DHCPMessage) + optoffset);
+ if (r < 0)
+ return r;
+
+ return 0;
+}
+
+static int parse_request(uint8_t code, uint8_t len, const void *option, void *userdata) {
+ DHCPRequest *req = userdata;
+
+ assert(req);
+
+ switch(code) {
+ case SD_DHCP_OPTION_IP_ADDRESS_LEASE_TIME:
+ if (len == 4)
+ req->lifetime = unaligned_read_be32(option);
+
+ break;
+ case SD_DHCP_OPTION_REQUESTED_IP_ADDRESS:
+ if (len == 4)
+ memcpy(&req->requested_ip, option, sizeof(be32_t));
+
+ break;
+ case SD_DHCP_OPTION_SERVER_IDENTIFIER:
+ if (len == 4)
+ memcpy(&req->server_id, option, sizeof(be32_t));
+
+ break;
+ case SD_DHCP_OPTION_CLIENT_IDENTIFIER:
+ if (len >= 2) {
+ uint8_t *data;
+
+ data = memdup(option, len);
+ if (!data)
+ return -ENOMEM;
+
+ free(req->client_id.data);
+ req->client_id.data = data;
+ req->client_id.length = len;
+ }
+
+ break;
+ case SD_DHCP_OPTION_MAXIMUM_MESSAGE_SIZE:
+
+ if (len == 2 && unaligned_read_be16(option) >= sizeof(DHCPPacket))
+ req->max_optlen = unaligned_read_be16(option) - sizeof(DHCPPacket);
+
+ break;
+ }
+
+ return 0;
+}
+
+static void dhcp_request_free(DHCPRequest *req) {
+ if (!req)
+ return;
+
+ free(req->client_id.data);
+ free(req);
+}
+
+DEFINE_TRIVIAL_CLEANUP_FUNC(DHCPRequest*, dhcp_request_free);
+
+static int ensure_sane_request(sd_dhcp_server *server, DHCPRequest *req, DHCPMessage *message) {
+ assert(req);
+ assert(message);
+
+ req->message = message;
+
+ /* set client id based on MAC address if client did not send an explicit
+ one */
+ if (!req->client_id.data) {
+ void *data;
+
+ data = malloc0(ETH_ALEN + 1);
+ if (!data)
+ return -ENOMEM;
+
+ ((uint8_t*) data)[0] = 0x01;
+ memcpy((uint8_t*) data + 1, &message->chaddr, ETH_ALEN);
+
+ req->client_id.length = ETH_ALEN + 1;
+ req->client_id.data = data;
+ }
+
+ if (req->max_optlen < DHCP_MIN_OPTIONS_SIZE)
+ req->max_optlen = DHCP_MIN_OPTIONS_SIZE;
+
+ if (req->lifetime <= 0)
+ req->lifetime = MAX(1ULL, server->default_lease_time);
+
+ if (server->max_lease_time > 0 && req->lifetime > server->max_lease_time)
+ req->lifetime = server->max_lease_time;
+
+ return 0;
+}
+
+static int get_pool_offset(sd_dhcp_server *server, be32_t requested_ip) {
+ assert(server);
+
+ if (!server->pool_size)
+ return -EINVAL;
+
+ if (be32toh(requested_ip) < (be32toh(server->subnet) | server->pool_offset) ||
+ be32toh(requested_ip) >= (be32toh(server->subnet) | (server->pool_offset + server->pool_size)))
+ return -ERANGE;
+
+ return be32toh(requested_ip & ~server->netmask) - server->pool_offset;
+}
+
+#define HASH_KEY SD_ID128_MAKE(0d,1d,fe,bd,f1,24,bd,b3,47,f1,dd,6e,73,21,93,30)
+
+int dhcp_server_handle_message(sd_dhcp_server *server, DHCPMessage *message,
+ size_t length) {
+ _cleanup_(dhcp_request_freep) DHCPRequest *req = NULL;
+ _cleanup_free_ char *error_message = NULL;
+ DHCPLease *existing_lease;
+ int type, r;
+
+ assert(server);
+ assert(message);
+
+ if (message->op != BOOTREQUEST ||
+ message->htype != ARPHRD_ETHER ||
+ message->hlen != ETHER_ADDR_LEN)
+ return 0;
+
+ req = new0(DHCPRequest, 1);
+ if (!req)
+ return -ENOMEM;
+
+ type = dhcp_option_parse(message, length, parse_request, req, &error_message);
+ if (type < 0)
+ return 0;
+
+ r = ensure_sane_request(server, req, message);
+ if (r < 0)
+ /* this only fails on critical errors */
+ return r;
+
+ existing_lease = hashmap_get(server->leases_by_client_id,
+ &req->client_id);
+
+ switch(type) {
+
+ case DHCP_DISCOVER: {
+ be32_t address = INADDR_ANY;
+ unsigned i;
+
+ log_dhcp_server(server, "DISCOVER (0x%x)",
+ be32toh(req->message->xid));
+
+ if (!server->pool_size)
+ /* no pool allocated */
+ return 0;
+
+ /* for now pick a random free address from the pool */
+ if (existing_lease)
+ address = existing_lease->address;
+ else {
+ struct siphash state;
+ uint64_t hash;
+ uint32_t next_offer;
+
+ /* even with no persistence of leases, we try to offer the same client
+ the same IP address. we do this by using the hash of the client id
+ as the offset into the pool of leases when finding the next free one */
+
+ siphash24_init(&state, HASH_KEY.bytes);
+ client_id_hash_func(&req->client_id, &state);
+ hash = htole64(siphash24_finalize(&state));
+ next_offer = hash % server->pool_size;
+
+ for (i = 0; i < server->pool_size; i++) {
+ if (!server->bound_leases[next_offer]) {
+ address = server->subnet | htobe32(server->pool_offset + next_offer);
+ break;
+ }
+
+ next_offer = (next_offer + 1) % server->pool_size;
+ }
+ }
+
+ if (address == INADDR_ANY)
+ /* no free addresses left */
+ return 0;
+
+ r = server_send_offer(server, req, address);
+ if (r < 0)
+ /* this only fails on critical errors */
+ return log_dhcp_server_errno(server, r, "Could not send offer: %m");
+
+ log_dhcp_server(server, "OFFER (0x%x)", be32toh(req->message->xid));
+ return DHCP_OFFER;
+ }
+ case DHCP_DECLINE:
+ log_dhcp_server(server, "DECLINE (0x%x): %s", be32toh(req->message->xid), strna(error_message));
+
+ /* TODO: make sure we don't offer this address again */
+
+ return 1;
+
+ case DHCP_REQUEST: {
+ be32_t address;
+ bool init_reboot = false;
+ int pool_offset;
+
+ /* see RFC 2131, section 4.3.2 */
+
+ if (req->server_id) {
+ log_dhcp_server(server, "REQUEST (selecting) (0x%x)",
+ be32toh(req->message->xid));
+
+ /* SELECTING */
+ if (req->server_id != server->address)
+ /* client did not pick us */
+ return 0;
+
+ if (req->message->ciaddr)
+ /* this MUST be zero */
+ return 0;
+
+ if (!req->requested_ip)
+ /* this must be filled in with the yiaddr
+ from the chosen OFFER */
+ return 0;
+
+ address = req->requested_ip;
+ } else if (req->requested_ip) {
+ log_dhcp_server(server, "REQUEST (init-reboot) (0x%x)",
+ be32toh(req->message->xid));
+
+ /* INIT-REBOOT */
+ if (req->message->ciaddr)
+ /* this MUST be zero */
+ return 0;
+
+ /* TODO: check more carefully if IP is correct */
+ address = req->requested_ip;
+ init_reboot = true;
+ } else {
+ log_dhcp_server(server, "REQUEST (rebinding/renewing) (0x%x)",
+ be32toh(req->message->xid));
+
+ /* REBINDING / RENEWING */
+ if (!req->message->ciaddr)
+ /* this MUST be filled in with clients IP address */
+ return 0;
+
+ address = req->message->ciaddr;
+ }
+
+ pool_offset = get_pool_offset(server, address);
+
+ /* verify that the requested address is from the pool, and either
+ owned by the current client or free */
+ if (pool_offset >= 0 &&
+ server->bound_leases[pool_offset] == existing_lease) {
+ DHCPLease *lease;
+ usec_t time_now = 0;
+
+ if (!existing_lease) {
+ lease = new0(DHCPLease, 1);
+ if (!lease)
+ return -ENOMEM;
+ lease->address = address;
+ lease->client_id.data = memdup(req->client_id.data,
+ req->client_id.length);
+ if (!lease->client_id.data) {
+ free(lease);
+ return -ENOMEM;
+ }
+ lease->client_id.length = req->client_id.length;
+ memcpy(&lease->chaddr, &req->message->chaddr,
+ ETH_ALEN);
+ lease->gateway = req->message->giaddr;
+ } else
+ lease = existing_lease;
+
+ r = sd_event_now(server->event,
+ clock_boottime_or_monotonic(),
+ &time_now);
+ if (r < 0) {
+ if (!existing_lease)
+ dhcp_lease_free(lease);
+ return r;
+ }
+
+ lease->expiration = req->lifetime * USEC_PER_SEC + time_now;
+
+ r = server_send_ack(server, req, address);
+ if (r < 0) {
+ /* this only fails on critical errors */
+ log_dhcp_server_errno(server, r, "Could not send ack: %m");
+
+ if (!existing_lease)
+ dhcp_lease_free(lease);
+
+ return r;
+ } else {
+ log_dhcp_server(server, "ACK (0x%x)",
+ be32toh(req->message->xid));
+
+ server->bound_leases[pool_offset] = lease;
+ hashmap_put(server->leases_by_client_id,
+ &lease->client_id, lease);
+
+ if (server->callback)
+ server->callback(server, SD_DHCP_SERVER_EVENT_LEASE_CHANGED, server->callback_userdata);
+
+ return DHCP_ACK;
+ }
+
+ } else if (init_reboot) {
+ r = server_send_nak(server, req);
+ if (r < 0)
+ /* this only fails on critical errors */
+ return log_dhcp_server_errno(server, r, "Could not send nak: %m");
+
+ log_dhcp_server(server, "NAK (0x%x)", be32toh(req->message->xid));
+ return DHCP_NAK;
+ }
+
+ break;
+ }
+
+ case DHCP_RELEASE: {
+ int pool_offset;
+
+ log_dhcp_server(server, "RELEASE (0x%x)",
+ be32toh(req->message->xid));
+
+ if (!existing_lease)
+ return 0;
+
+ if (existing_lease->address != req->message->ciaddr)
+ return 0;
+
+ pool_offset = get_pool_offset(server, req->message->ciaddr);
+ if (pool_offset < 0)
+ return 0;
+
+ if (server->bound_leases[pool_offset] == existing_lease) {
+ server->bound_leases[pool_offset] = NULL;
+ hashmap_remove(server->leases_by_client_id, existing_lease);
+ dhcp_lease_free(existing_lease);
+
+ if (server->callback)
+ server->callback(server, SD_DHCP_SERVER_EVENT_LEASE_CHANGED, server->callback_userdata);
+ }
+
+ return 0;
+ }}
+
+ return 0;
+}
+
+static int server_receive_message(sd_event_source *s, int fd,
+ uint32_t revents, void *userdata) {
+ _cleanup_free_ DHCPMessage *message = NULL;
+ CMSG_BUFFER_TYPE(CMSG_SPACE(sizeof(struct in_pktinfo))) control;
+ sd_dhcp_server *server = userdata;
+ struct iovec iov = {};
+ struct msghdr msg = {
+ .msg_iov = &iov,
+ .msg_iovlen = 1,
+ .msg_control = &control,
+ .msg_controllen = sizeof(control),
+ };
+ struct cmsghdr *cmsg;
+ ssize_t buflen, len;
+ int r;
+
+ assert(server);
+
+ buflen = next_datagram_size_fd(fd);
+ if (buflen < 0)
+ return buflen;
+
+ message = malloc(buflen);
+ if (!message)
+ return -ENOMEM;
+
+ iov = IOVEC_MAKE(message, buflen);
+
+ len = recvmsg_safe(fd, &msg, 0);
+ if (IN_SET(len, -EAGAIN, -EINTR))
+ return 0;
+ if (len < 0)
+ return len;
+ if ((size_t) len < sizeof(DHCPMessage))
+ return 0;
+
+ CMSG_FOREACH(cmsg, &msg) {
+ if (cmsg->cmsg_level == IPPROTO_IP &&
+ cmsg->cmsg_type == IP_PKTINFO &&
+ cmsg->cmsg_len == CMSG_LEN(sizeof(struct in_pktinfo))) {
+ struct in_pktinfo *info = (struct in_pktinfo*)CMSG_DATA(cmsg);
+
+ /* TODO figure out if this can be done as a filter on
+ * the socket, like for IPv6 */
+ if (server->ifindex != info->ipi_ifindex)
+ return 0;
+
+ break;
+ }
+ }
+
+ r = dhcp_server_handle_message(server, message, (size_t) len);
+ if (r < 0)
+ log_dhcp_server_errno(server, r, "Couldn't process incoming message: %m");
+
+ return 0;
+}
+
+int sd_dhcp_server_start(sd_dhcp_server *server) {
+ int r;
+
+ assert_return(server, -EINVAL);
+ assert_return(server->event, -EINVAL);
+ assert_return(!server->receive_message, -EBUSY);
+ assert_return(server->fd_raw < 0, -EBUSY);
+ assert_return(server->fd < 0, -EBUSY);
+ assert_return(server->address != htobe32(INADDR_ANY), -EUNATCH);
+
+ r = socket(AF_PACKET, SOCK_DGRAM | SOCK_CLOEXEC | SOCK_NONBLOCK, 0);
+ if (r < 0) {
+ r = -errno;
+ sd_dhcp_server_stop(server);
+ return r;
+ }
+ server->fd_raw = r;
+
+ r = dhcp_network_bind_udp_socket(server->ifindex, INADDR_ANY, DHCP_PORT_SERVER, -1);
+ if (r < 0) {
+ sd_dhcp_server_stop(server);
+ return r;
+ }
+ server->fd = r;
+
+ r = sd_event_add_io(server->event, &server->receive_message,
+ server->fd, EPOLLIN,
+ server_receive_message, server);
+ if (r < 0) {
+ sd_dhcp_server_stop(server);
+ return r;
+ }
+
+ r = sd_event_source_set_priority(server->receive_message,
+ server->event_priority);
+ if (r < 0) {
+ sd_dhcp_server_stop(server);
+ return r;
+ }
+
+ log_dhcp_server(server, "STARTED");
+
+ return 0;
+}
+
+int sd_dhcp_server_forcerenew(sd_dhcp_server *server) {
+ unsigned i;
+ int r = 0;
+
+ assert_return(server, -EINVAL);
+ assert(server->bound_leases);
+
+ for (i = 0; i < server->pool_size; i++) {
+ DHCPLease *lease = server->bound_leases[i];
+
+ if (!lease || lease == &server->invalid_lease)
+ continue;
+
+ r = server_send_forcerenew(server, lease->address,
+ lease->gateway,
+ lease->chaddr);
+ if (r < 0)
+ return r;
+
+ log_dhcp_server(server, "FORCERENEW");
+ }
+
+ return r;
+}
+
+int sd_dhcp_server_set_timezone(sd_dhcp_server *server, const char *tz) {
+ int r;
+
+ assert_return(server, -EINVAL);
+ assert_return(timezone_is_valid(tz, LOG_DEBUG), -EINVAL);
+
+ if (streq_ptr(tz, server->timezone))
+ return 0;
+
+ r = free_and_strdup(&server->timezone, tz);
+ if (r < 0)
+ return r;
+
+ return 1;
+}
+
+int sd_dhcp_server_set_max_lease_time(sd_dhcp_server *server, uint32_t t) {
+ assert_return(server, -EINVAL);
+
+ if (t == server->max_lease_time)
+ return 0;
+
+ server->max_lease_time = t;
+ return 1;
+}
+
+int sd_dhcp_server_set_default_lease_time(sd_dhcp_server *server, uint32_t t) {
+ assert_return(server, -EINVAL);
+
+ if (t == server->default_lease_time)
+ return 0;
+
+ server->default_lease_time = t;
+ return 1;
+}
+
+int sd_dhcp_server_set_servers(
+ sd_dhcp_server *server,
+ sd_dhcp_lease_server_type what,
+ const struct in_addr addresses[],
+ size_t n_addresses) {
+
+ struct in_addr *c = NULL;
+
+ assert_return(server, -EINVAL);
+ assert_return(addresses || n_addresses == 0, -EINVAL);
+ assert_return(what >= 0, -EINVAL);
+ assert_return(what < _SD_DHCP_LEASE_SERVER_TYPE_MAX, -EINVAL);
+
+ if (server->servers[what].size == n_addresses &&
+ memcmp(server->servers[what].addr, addresses, sizeof(struct in_addr) * n_addresses) == 0)
+ return 0;
+
+ if (n_addresses > 0) {
+ c = newdup(struct in_addr, addresses, n_addresses);
+ if (!c)
+ return -ENOMEM;
+ }
+
+ free(server->servers[what].addr);
+ server->servers[what].addr = c;
+ server->servers[what].size = n_addresses;
+ return 1;
+}
+
+int sd_dhcp_server_set_dns(sd_dhcp_server *server, const struct in_addr dns[], size_t n) {
+ return sd_dhcp_server_set_servers(server, SD_DHCP_LEASE_DNS, dns, n);
+}
+int sd_dhcp_server_set_ntp(sd_dhcp_server *server, const struct in_addr ntp[], size_t n) {
+ return sd_dhcp_server_set_servers(server, SD_DHCP_LEASE_NTP, ntp, n);
+}
+int sd_dhcp_server_set_sip(sd_dhcp_server *server, const struct in_addr sip[], size_t n) {
+ return sd_dhcp_server_set_servers(server, SD_DHCP_LEASE_SIP, sip, n);
+}
+int sd_dhcp_server_set_pop3(sd_dhcp_server *server, const struct in_addr pop3[], size_t n) {
+ return sd_dhcp_server_set_servers(server, SD_DHCP_LEASE_POP3, pop3, n);
+}
+int sd_dhcp_server_set_smtp(sd_dhcp_server *server, const struct in_addr smtp[], size_t n) {
+ return sd_dhcp_server_set_servers(server, SD_DHCP_LEASE_SMTP, smtp, n);
+}
+int sd_dhcp_server_set_lpr(sd_dhcp_server *server, const struct in_addr lpr[], size_t n) {
+ return sd_dhcp_server_set_servers(server, SD_DHCP_LEASE_LPR, lpr, n);
+}
+
+int sd_dhcp_server_set_emit_router(sd_dhcp_server *server, int enabled) {
+ assert_return(server, -EINVAL);
+
+ if (enabled == server->emit_router)
+ return 0;
+
+ server->emit_router = enabled;
+
+ return 1;
+}
+
+int sd_dhcp_server_add_option(sd_dhcp_server *server, sd_dhcp_option *v) {
+ int r;
+
+ assert_return(server, -EINVAL);
+ assert_return(v, -EINVAL);
+
+ r = ordered_hashmap_ensure_allocated(&server->extra_options, &dhcp_option_hash_ops);
+ if (r < 0)
+ return r;
+
+ r = ordered_hashmap_put(server->extra_options, UINT_TO_PTR(v->option), v);
+ if (r < 0)
+ return r;
+
+ sd_dhcp_option_ref(v);
+ return 0;
+}
+
+int sd_dhcp_server_add_vendor_option(sd_dhcp_server *server, sd_dhcp_option *v) {
+ int r;
+
+ assert_return(server, -EINVAL);
+ assert_return(v, -EINVAL);
+
+ r = ordered_hashmap_ensure_allocated(&server->vendor_options, &dhcp_option_hash_ops);
+ if (r < 0)
+ return -ENOMEM;
+
+ r = ordered_hashmap_put(server->vendor_options, v, v);
+ if (r < 0)
+ return r;
+
+ sd_dhcp_option_ref(v);
+
+ return 1;
+}
+
+int sd_dhcp_server_set_callback(sd_dhcp_server *server, sd_dhcp_server_callback_t cb, void *userdata) {
+ assert_return(server, -EINVAL);
+
+ server->callback = cb;
+ server->callback_userdata = userdata;
+
+ return 0;
+}