dhcp6s.c

IPv6环境下的DHCP实现

	struct dhcp6_optinfo optinfo;

	memset(&iov, 0, sizeof(iov));
	memset(&mhdr, 0, sizeof(mhdr));

	iov.iov_base = rdatabuf;
	iov.iov_len = sizeof(rdatabuf);
	mhdr.msg_name = &from;
	mhdr.msg_namelen = sizeof(from);
	mhdr.msg_iov = &iov;
	mhdr.msg_iovlen = 1;
	mhdr.msg_control = (caddr_t)cmsgbuf;
	mhdr.msg_controllen = sizeof(cmsgbuf);

	if ((len = recvmsg(insock, &mhdr, 0)) < 0) {
		dprintf(LOG_ERR, "%s" "recvmsg: %s", FNAME, strerror(errno));
		return -1;
	}

	for (cm = (struct cmsghdr *)CMSG_FIRSTHDR(&mhdr); cm;
	     cm = (struct cmsghdr *)CMSG_NXTHDR(&mhdr, cm)) {
		if (cm->cmsg_level == IPPROTO_IPV6 &&
		    cm->cmsg_type == IPV6_PKTINFO &&
		    cm->cmsg_len == CMSG_LEN(sizeof(struct in6_pktinfo))) {
			pi = (struct in6_pktinfo *)(CMSG_DATA(cm));
		}
	}
	if (pi == NULL) {
		dprintf(LOG_NOTICE, "%s" "failed to get packet info", FNAME);
		return -1;
	}
	if ((ifp = find_ifconfbyid((unsigned int)pi->ipi6_ifindex)) == NULL) {
		dprintf(LOG_INFO, "%s" "unexpected interface (%d)", FNAME,
		    (unsigned int)pi->ipi6_ifindex);
		return;
	}

	if (len < sizeof(*dh6)) {
		dprintf(LOG_INFO, "%s" "short packet", FNAME);
		return -1;
	}
	
	dh6 = (struct dhcp6 *)rdatabuf;

	dprintf(LOG_DEBUG, "%s" "received %s from %s", FNAME,
	    dhcp6msgstr(dh6->dh6_msgtype),
	    addr2str((struct sockaddr *)&from));

	/*
	 * parse and validate options in the request
	 */
	dhcp6_init_options(&optinfo);
	if (dhcp6_get_options((struct dhcp6opt *)(dh6 + 1),
	    (struct dhcp6opt *)(rdatabuf + len), &optinfo) < 0) {
		dprintf(LOG_INFO, "%s" "failed to parse options", FNAME);
		return -1;
	}

	switch (dh6->dh6_msgtype) {
	case DH6_SOLICIT:
		(void)server6_react_solicit(ifp, dh6, &optinfo,
		    (struct sockaddr *)&from, fromlen);
		break;
	case DH6_REQUEST:
		(void)server6_react_request(ifp, pi, dh6, &optinfo,
		    (struct sockaddr *)&from, fromlen);
		break;
	case DH6_RENEW:
		(void)server6_react_renew(ifp, pi, dh6, &optinfo,
		    (struct sockaddr *)&from, fromlen);
		break;
	case DH6_REBIND:
		(void)server6_react_rebind(ifp, dh6, &optinfo,
		    (struct sockaddr *)&from, fromlen);
		break;
	case DH6_INFORM_REQ:
		(void)server6_react_informreq(ifp, dh6, &optinfo,
		    (struct sockaddr *)&from, fromlen);
		break;
	default:
		dprintf(LOG_INFO, "%s" "unknown or unsupported msgtype %s",
		    FNAME, dhcp6msgstr(dh6->dh6_msgtype));
		break;
	}

	dhcp6_clear_options(&optinfo);

	return 0;
}

static int
server6_react_solicit(ifp, dh6, optinfo, from, fromlen)
	struct dhcp6_if *ifp;
	struct dhcp6 *dh6;
	struct dhcp6_optinfo *optinfo;
	struct sockaddr *from;
	int fromlen;
{
	struct dhcp6_optinfo roptinfo;
	struct host_conf *client_conf;
	struct dhcp6_listval *opt;
	struct dhcp6_list ret_prefix_list;
	int resptype, do_binding = 0, error;

	/*
	 * Servers MUST discard any Solicit messages that do not include a
	 * Client Identifier option. [dhcpv6-26 Section 15.2]
	 */
	if (optinfo->clientID.duid_len == 0) {
		dprintf(LOG_INFO, "%s" "no client ID option", FNAME);
		return(-1);
	} else {
		dprintf(LOG_DEBUG, "%s" "client ID %s", FNAME,
			duidstr(&optinfo->clientID));
	}

	/* get per-host configuration for the client, if any. */
	if ((client_conf = find_hostconf(&optinfo->clientID))) {
		dprintf(LOG_DEBUG, "%s" "found a host configuration for %s",
			FNAME, client_conf->name);
	}

	/*
	 * configure necessary options based on the options in solicit.
	 */
	dhcp6_init_options(&roptinfo);

	/* server information option */
	if (duidcpy(&roptinfo.serverID, &server_duid)) {
		dprintf(LOG_ERR, "%s" "failed to copy server ID", FNAME);
		goto fail;
	}

	/* copy client information back (if provided) */
	if (optinfo->clientID.duid_id &&
	    duidcpy(&roptinfo.clientID, &optinfo->clientID)) {
		dprintf(LOG_ERR, "%s" "failed to copy client ID", FNAME);
		goto fail;
	}

	/* preference (if configured) */
	if (ifp->server_pref != DH6OPT_PREF_UNDEF)
		roptinfo.pref = ifp->server_pref;

	/* DNS server */
	if (dhcp6_copy_list(&roptinfo.dns_list, &dnslist)) {
		dprintf(LOG_ERR, "%s" "failed to copy DNS servers", FNAME);
		goto fail;
	}

	/*
	 * see if we have information for requested options, and if so,
	 * configure corresponding options.
	 */
	if (optinfo->rapidcommit && (ifp->allow_flags & DHCIFF_RAPID_COMMIT))
		do_binding = 1;
	for (opt = TAILQ_FIRST(&optinfo->reqopt_list); opt;
	     opt = TAILQ_NEXT(opt, link)) {
		switch(opt->val_num) {
		case DH6OPT_PREFIX_DELEGATION:
			create_conflist(DHCP6_CONFINFO_PREFIX,
			    &optinfo->clientID, &roptinfo.prefix_list,
			    client_conf ? &client_conf->prefix_list : NULL,
			    TAILQ_EMPTY(&optinfo->prefix_list) ?
			    NULL : &optinfo->prefix_list,
			    do_binding);
			break;
		}
	}

	if (optinfo->rapidcommit && (ifp->allow_flags & DHCIFF_RAPID_COMMIT)) {
		/*
		 * If the client has included a Rapid Commit option and the
		 * server has been configured to respond with committed address
		 * assignments and other resources, responds to the Solicit
		 * with a Reply message.
		 * [dhcpv6-26 Section 17.2.1]
		 */
		roptinfo.rapidcommit = 1;
		resptype = DH6_REPLY;
	} else
		resptype = DH6_ADVERTISE;

	error = server6_send(resptype, ifp, dh6, optinfo, from, fromlen,
			     &roptinfo);
	dhcp6_clear_options(&roptinfo);
	return(error);

  fail:
	dhcp6_clear_options(&roptinfo);
	return -1;
}

static int
server6_react_request(ifp, pi, dh6, optinfo, from, fromlen)
	struct dhcp6_if *ifp;
	struct in6_pktinfo *pi;
	struct dhcp6 *dh6;
	struct dhcp6_optinfo *optinfo;
	struct sockaddr *from;
	int fromlen;
{
	struct dhcp6_optinfo roptinfo;
	struct host_conf *client_conf;
	struct dhcp6_listval *opt, *p;

	/* message validation according to Section 15.4 of dhcpv6-26 */

	/* the message must include a Server Identifier option */
	if (optinfo->serverID.duid_len == 0) {
		dprintf(LOG_INFO, "%s" "no server ID option", FNAME);
		return -1;
	}
	/* the contents of the Server Identifier option must match ours */
	if (duidcmp(&optinfo->serverID, &server_duid)) {
		dprintf(LOG_INFO, "%s" "server ID mismatch", FNAME);
		return -1;
	}
	/* the message must include a Client Identifier option */
	if (optinfo->clientID.duid_len == 0) {
		dprintf(LOG_INFO, "%s" "no server ID option", FNAME);
		return -1;
	}

	/*
	 * configure necessary options based on the options in request.
	 */
	dhcp6_init_options(&roptinfo);

	/* server information option */
	if (duidcpy(&roptinfo.serverID, &server_duid)) {
		dprintf(LOG_ERR, "%s" "failed to copy server ID", FNAME);
		goto fail;
	}
	/* copy client information back */
	if (duidcpy(&roptinfo.clientID, &optinfo->clientID)) {
		dprintf(LOG_ERR, "%s" "failed to copy client ID", FNAME);
		goto fail;
	}

	/*
	 * When the server receives a Request message via unicast from a
	 * client to which the server has not sent a unicast option, the server
	 * discards the Request message and responds with a Reply message
	 * containing a Status Code option with value UseMulticast, a Server
	 * Identifier option containing the server's DUID, the Client
	 * Identifier option from the client message and no other options.
	 * [dhcpv6-26 18.2.1]
	 * (Our current implementation never sends a unicast option.)
	 */
	if (!IN6_IS_ADDR_MULTICAST(&pi->ipi6_addr)) {
		int stcode = DH6OPT_STCODE_USEMULTICAST;

		dprintf(LOG_INFO, "%s" "unexpected unicast message from %s",
		    FNAME, addr2str(from));
		if (dhcp6_add_listval(&roptinfo.stcode_list, &stcode,
		    DHCP6_LISTVAL_NUM) == NULL) {
			dprintf(LOG_ERR, "%s" "failed to add a status code",
			    FNAME);
			goto fail;
		}
		server6_send(DH6_REPLY, ifp, dh6, optinfo, from,
		    fromlen, &roptinfo);
		goto end;
	}

	/* get per-host configuration for the client, if any. */
	if ((client_conf = find_hostconf(&optinfo->clientID))) {
		dprintf(LOG_DEBUG, "%s" "found a host configuration named %s",
			FNAME, client_conf->name);
	}

	/*
	 * See if we have to make a binding of some configuration information
	 * for the client.
	 * (Note that our implementation does not assign addresses (nor will)).
	 */
	/* prefixes */
	create_conflist(DHCP6_CONFINFO_PREFIX,
	    &optinfo->clientID, &roptinfo.prefix_list,
	    client_conf ? &client_conf->prefix_list : NULL,
	    &optinfo->prefix_list,
	    1);

	/*
	 * If the Request message contained an Option Request option, the
	 * server MUST include options in the Reply message for any options in
	 * the Option Request option the server is configured to return to the
	 * client.
	 * [dhcpv6-26 18.2.1]
	 * Note: our current implementation always includes all information
	 * that we can provide.  So we do not have to check the option request
	 * options.
	 */
#if 0
	for (opt = TAILQ_FIRST(&optinfo->reqopt_list); opt;
	     opt = TAILQ_NEXT(opt, link)) {
		;
	}
#endif

	/*
	 * Adds options to the Reply message for any other configuration
	 * information to be assigned to the client.
	 */
	/* DNS server */
	if (dhcp6_copy_list(&roptinfo.dns_list, &dnslist)) {
		dprintf(LOG_ERR, "%s" "failed to copy DNS servers", FNAME);
		goto fail;
	}

	/* send a reply message. */
	(void)server6_send(DH6_REPLY, ifp, dh6, optinfo, from, fromlen,
			   &roptinfo);

  end:
	dhcp6_clear_options(&roptinfo);
	return 0;

  fail:
	dhcp6_clear_options(&roptinfo);
	return -1;
}

static int
server6_react_renew(ifp, pi, dh6, optinfo, from, fromlen)
	struct dhcp6_if *ifp;
	struct in6_pktinfo *pi;
	struct dhcp6 *dh6;
	struct dhcp6_optinfo *optinfo;
	struct sockaddr *from;
	int fromlen;
{
	struct dhcp6_optinfo roptinfo;
	struct dhcp6_listval *lv;
	struct dhcp6_binding *binding;
	int add_success = 0;

	/* message validation according to Section 15.6 of dhcpv6-26 */

	/* the message must include a Server Identifier option */
	if (optinfo->serverID.duid_len == 0) {
		dprintf(LOG_INFO, "%s" "no server ID option", FNAME);
		return -1;
	}
	/* the contents of the Server Identifier option must match ours */
	if (duidcmp(&optinfo->serverID, &server_duid)) {
		dprintf(LOG_INFO, "%s" "server ID mismatch", FNAME);
		return -1;
	}
	/* the message must include a Client Identifier option */
	if (optinfo->clientID.duid_len == 0) {
		dprintf(LOG_INFO, "%s" "no server ID option", FNAME);
		return -1;
	}

	/*
	 * configure necessary options based on the options in request.
	 */
	dhcp6_init_options(&roptinfo);

	/* server information option */
	if (duidcpy(&roptinfo.serverID, &server_duid)) {
		dprintf(LOG_ERR, "%s" "failed to copy server ID", FNAME);
		goto fail;
	}
	/* copy client information back */
	if (duidcpy(&roptinfo.clientID, &optinfo->clientID)) {
		dprintf(LOG_ERR, "%s" "failed to copy client ID", FNAME);
		goto fail;
	}

	/*
	 * When the server receives a Renew message via unicast from a
	 * client to which the server has not sent a unicast option, the server
	 * discards the Request message and responds with a Reply message
	 * containing a status code option with value UseMulticast, a Server
	 * Identifier option containing the server's DUID, the Client
	 * Identifier option from the client message and no other options.
	 * [dhcpv6-26 18.2.3]
	 * (Our current implementation never sends a unicast option.)
	 */
	if (!IN6_IS_ADDR_MULTICAST(&pi->ipi6_addr)) {
		int stcode = DH6OPT_STCODE_USEMULTICAST;

		dprintf(LOG_INFO, "%s" "unexpected unicast message from %s",
		    FNAME, addr2str(from));
		if (dhcp6_add_listval(&roptinfo.stcode_list, &stcode,
		    DHCP6_LISTVAL_NUM) == NULL) {
			dprintf(LOG_ERR, "%s" "failed to add a status code",
			    FNAME);
			goto fail;
		}
		server6_send(DH6_REPLY, ifp, dh6, optinfo, from,
		    fromlen, &roptinfo);
		goto end;
	}

	/*
	 * Locates the client's binding and verifies that the information
	 * from the client matches the information stored for that client.
	 */
	/* prefixes */
	for (lv = TAILQ_FIRST(&optinfo->prefix_list); lv;
	     lv = TAILQ_NEXT(lv, link)) {
		binding = find_binding(&optinfo->clientID,
				       DHCP6_CONFINFO_PREFIX,
				       &lv->val_prefix6);
		if (binding == NULL) {
			dprintf(LOG_INFO, "%s" "can't find a binding of prefix"
				" %s/%d for %s", FNAME,
				in6addr2str(&lv->val_prefix6.addr, 0),
				lv->val_prefix6.plen,
				duidstr(&optinfo->clientID));
			continue; /* XXX: is this okay? */
		}

		/* we always extend the requested binding. */
		update_binding(binding);

		/* include a Status Code option with value Success. */
		if (!add_success) {
			int stcode = DH6OPT_STCODE_SUCCESS;

			if (dhcp6_add_listval(&roptinfo.stcode_list,
			    &stcode, DHCP6_LISTVAL_NUM) == NULL) {
				dprintf(LOG_ERR, "%s" "failed to add a "
				    "status code", FNAME);
			}
			add_success = 1;
		}

		/* add the prefix */
		if (dhcp6_add_listval(&roptinfo.prefix_list, binding->val,
		    DHCP6_LISTVAL_PREFIX6) == NULL) {
			dprintf(LOG_ERR, "%s" "failed to add a renewed prefix",
			    FNAME);
			goto fail;
		}
	}

	(void)server6_send(DH6_REPLY, ifp, dh6, optinfo, from, fromlen,
			   &roptinfo);

  end:
	dhcp6_clear_options(&roptinfo);
	return 0;

  fail:
	dhcp6_clear_options(&roptinfo);
	return -1;
}

static int
server6_react_rebind(ifp, dh6, optinfo, from, fromlen)
	struct dhcp6_if *ifp;
	struct dhcp6 *dh6;
	struct dhcp6_optinfo *optinfo;
	struct sockaddr *from;
	int fromlen;
{
	struct dhcp6_optinfo roptinfo;
	struct dhcp6_listval *lv;
	struct dhcp6_binding *binding;
	int add_success = 0;