#include "dhcp-server-internal.h"
#include "dhcp-internal.h"
+#define DHCP_DEFAULT_LEASE_TIME 60
+
+int sd_dhcp_server_set_lease_pool(sd_dhcp_server *server, struct in_addr *address,
+ size_t size) {
+ assert_return(server, -EINVAL);
+ assert_return(address, -EINVAL);
+ assert_return(address->s_addr, -EINVAL);
+ assert_return(size, -EINVAL);
+ assert_return(server->pool_start == htobe32(INADDR_ANY), -EBUSY);
+ assert_return(!server->pool_size, -EBUSY);
+
+ server->pool_start = address->s_addr;
+ server->pool_size = size;
+
+ return 0;
+}
+
+int sd_dhcp_server_set_address(sd_dhcp_server *server, struct in_addr *address) {
+ assert_return(server, -EINVAL);
+ assert_return(address, -EINVAL);
+ assert_return(address->s_addr, -EINVAL);
+ assert_return(server->address == htobe32(INADDR_ANY), -EBUSY);
+
+ server->address = address->s_addr;
+
+ return 0;
+}
+
sd_dhcp_server *sd_dhcp_server_ref(sd_dhcp_server *server) {
if (server)
assert_se(REFCNT_INC(server->n_ref) >= 2);
server->n_ref = REFCNT_INIT;
server->fd_raw = -1;
server->fd = -1;
+ server->address = htobe32(INADDR_ANY);
server->index = ifindex;
*ret = server;
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 = htons(ETH_P_IP),
+ .ll.sll_ifindex = server->index,
+ .ll.sll_halen = ETH_ALEN,
+ };
+ int r;
+
+ assert(server);
+ assert(server->index > 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);
+
+ r = dhcp_network_send_raw_socket(server->fd_raw, &link, packet, len);
+ if (r < 0)
+ return r;
+
+ return 0;
+}
+
+static int dhcp_server_send_udp(sd_dhcp_server *server, be32_t destination,
+ DHCPMessage *message, size_t len) {
+ union sockaddr_union dest = {
+ .in.sin_family = AF_INET,
+ .in.sin_port = htobe16(DHCP_PORT_CLIENT),
+ .in.sin_addr.s_addr = destination,
+ };
+ struct iovec iov = {
+ .iov_base = message,
+ .iov_len = len,
+ };
+ uint8_t cmsgbuf[CMSG_LEN(sizeof(struct in_pktinfo))] = {};
+ struct msghdr msg = {
+ .msg_name = &dest,
+ .msg_namelen = sizeof(dest.in),
+ .msg_iov = &iov,
+ .msg_iovlen = 1,
+ .msg_control = cmsgbuf,
+ .msg_controllen = sizeof(cmsgbuf),
+ };
+ struct cmsghdr *cmsg;
+ struct in_pktinfo *pktinfo;
+ int r;
+
+ 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->index;
+ pktinfo->ipi_spec_dst.s_addr = server->address;
+
+ r = sendmsg(server->fd, &msg, 0);
+ if (r < 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;
+ 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,
+ DHCP_OPTION_SERVER_IDENTIFIER,
+ 4, &server->address);
+ if (r < 0)
+ return r;
+
+ r = dhcp_option_append(&packet->dhcp, req->max_optlen, &optoffset, 0,
+ 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;
+ if (type == DHCP_NAK)
+ packet->dhcp.flags = htobe16(0x8000);
+ } else if (req->message->ciaddr && type != DHCP_NAK)
+ destination = req->message->ciaddr;
+
+ if (destination || requested_broadcast(req) || type == DHCP_NAK)
+ return dhcp_server_send_udp(server, destination, &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;
+ int r;
+
+ assert(server);
+ assert(ret);
+ assert(_optoffset);
+ assert(IN_SET(type, DHCP_OFFER, DHCP_ACK));
+
+ packet = malloc0(sizeof(DHCPPacket) + req->max_optlen);
+ if (!packet)
+ return -ENOMEM;
+
+ r = dhcp_message_init(&packet->dhcp, BOOTREPLY, be32toh(req->message->xid),
+ type, 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 = packet;
+ packet = NULL;
+
+ 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;
+
+ /* for one minute */
+ lease_time = htobe32(DHCP_DEFAULT_LEASE_TIME);
+ r = dhcp_option_append(&packet->dhcp, req->max_optlen, &offset, 0,
+ DHCP_OPTION_IP_ADDRESS_LEASE_TIME, 4, &lease_time);
+ 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) {
+ _cleanup_free_ DHCPPacket *packet = NULL;
+ size_t offset;
+ be32_t lease_time;
+ int r;
+
+ r = server_message_init(server, &packet, DHCP_ACK, &offset, req);
+ if (r < 0)
+ return r;
+
+ packet->dhcp.yiaddr = address;
+
+ /* for ten seconds */
+ lease_time = htobe32(DHCP_DEFAULT_LEASE_TIME);
+ r = dhcp_option_append(&packet->dhcp, req->max_optlen, &offset, 0,
+ DHCP_OPTION_IP_ADDRESS_LEASE_TIME, 4, &lease_time);
+ 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 parse_request(uint8_t code, uint8_t len, const uint8_t *option,
void *user_data) {
DHCPRequest *req = user_data;
assert(req);
switch(code) {
+ case DHCP_OPTION_REQUESTED_IP_ADDRESS:
+ if (len == 4)
+ req->requested_ip = *(be32_t*)option;
+
+ break;
case DHCP_OPTION_SERVER_IDENTIFIER:
if (len == 4)
req->server_id = *(be32_t*)option;
/* this only fails on critical errors */
return r;
- log_dhcp_server(server, "received message of type %d", type);
+ switch(type) {
+ case DHCP_DISCOVER:
+ {
+ be32_t address;
+
+ 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 address from the pool */
+ address = htobe32(be32toh(server->pool_start) +
+ (random_u32() % server->pool_size));
+
+ r = server_send_offer(server, req, address);
+ if (r < 0) {
+ /* this only fails on critical errors */
+ log_dhcp_server(server, "could not send offer: %s",
+ strerror(-r));
+ return r;
+ } else {
+ log_dhcp_server(server, "OFFER (0x%x)",
+ be32toh(req->message->xid));
+ return DHCP_OFFER;
+ }
+
+ break;
+ }
+ case DHCP_REQUEST:
+ {
+ be32_t address;
+
+ /* 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 if requested IP is correct, NAK if not */
+ address = req->requested_ip;
+ } 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;
+ }
- return 1;
+ /* for now we just verify that the address is from the pool, not
+ whether or not it is taken */
+ if (htobe32(req->requested_ip) >= htobe32(server->pool_start) &&
+ htobe32(req->requested_ip) < htobe32(server->pool_start) +
+ + server->pool_size) {
+ r = server_send_ack(server, req, address);
+ if (r < 0) {
+ /* this only fails on critical errors */
+ log_dhcp_server(server, "could not send ack: %s",
+ strerror(-r));
+ return r;
+ } else {
+ log_dhcp_server(server, "ACK (0x%x)",
+ be32toh(req->message->xid));
+ return DHCP_ACK;
+ }
+ } else
+ return 0;
+
+ break;
+ }
+ }
+
+ return 0;
}
static int server_receive_message(sd_event_source *s, int fd,
assert_return(!server->receive_message, -EBUSY);
assert_return(server->fd_raw == -1, -EBUSY);
assert_return(server->fd == -1, -EBUSY);
+ assert_return(server->address != htobe32(INADDR_ANY), -EUNATCH);
r = socket(AF_PACKET, SOCK_DGRAM | SOCK_NONBLOCK, 0);
if (r < 0) {
~ianmdlvl / elogind.git / blobdiff