dhcp: delay restarts after NAKs The server might answer to a DHCPREQUEST with a NAK and currently the client restarts the configuration process immediately. It was observed that this can easily generate loops in which the network is flooded with DISCOVER,OFFER,REQUEST,NAK sequences. RFC 2131 only states that "if the client receives a DHCPNAK message, the client restarts the configuration process" without further details. Add a delay with exponential backoff between retries after NAKs to limit the number of requests and cap the delay to 30 minutes.

dhcp: make DHCP_OPTION_* enum public libsystemd-network provides the public function sd_dhcp_client_set_request_option() to enable the request of a given DHCP option. However the enum defining such options is defined in the internal header dhcp-protocol.h. Move the enum definition to the public header sd-dhcp-client.h and properly namespace values.

util-lib: update dns_name_to_wire_format() to optionally generate DNSSEC canonical names We'll need this later when putting together RR serializations to checksum.

tree-wide: expose "p"-suffix unref calls in public APIs to make gcc cleanup easy GLIB has recently started to officially support the gcc cleanup attribute in its public API, hence let's do the same for our APIs. With this patch we'll define an xyz_unrefp() call for each public xyz_unref() call, to make it easy to use inside a __attribute__((cleanup())) expression. Then, all code is ported over to make use of this. The new calls are also documented in the man pages, with examples how to use them (well, I only added docs where the _unref() call itself already had docs, and the examples, only cover sd_bus_unrefp() and sd_event_unrefp()). This also renames sd_lldp_free() to sd_lldp_unref(), since that's how we tend to call our destructors these days. Note that this defines no public macro that wraps gcc's attribute and makes it easier to use. While I think it's our duty in the library to make our stuff easy to use, I figure it's not our duty to make gcc's own features easy to use on its own. Most likely, client code which wants to make use of this should define its own: #define _cleanup_(function) __attribute__((cleanup(function))) Or similar, to make the gcc feature easier to use. Making this logic public has the benefit that we can remove three header files whose only purpose was to define these functions internally. See #2008.

dns-domain: simplify dns_name_is_root() and dns_name_is_single_label() Let's change the return value to bool. If we encounter an error while parsing, return "false" instead of the actual parsing error, after all the specified hostname does not qualify for what the function is supposed to test. Dealing with the additional error codes was always cumbersome, and easily misused, like for example in the DHCP code. Let's also rename the functions from dns_name_root() to dns_name_is_root(), to indicate that this function checks something and returns a bool. Similar for dns_name_is_signal_label().

sd-dhcp: parse error message in DECLINE or NAK If a client sends a DECLINE or a server sends a NAK, they can include a string with a message to explain the error. Parse this and print it at debug level.

libsystemd-network: clean up recv functions

libsystemd-network: add support for "Client FQDN" DHCP option This adds support for the Client Fully Qualified Domain Name (FQDN) option [RFC 4702] to libsystemd-network. The option can be used to exchange information about a DHCPv4 client's fully qualified domain name and about responsibility for updating the DNS RR related to the client's address assignment. Other popular DHCP clients (dhclient, dhcpcd) support this option and it would be useful to have it in networkd too.

doc: correct orthography, word forms and missing/extraneous words

util-lib: split out allocation calls into alloc-util.[ch]

util-lib: split our string related calls from util.[ch] into its own file string-util.[ch] There are more than enough calls doing string manipulations to deserve its own files, hence do something about it. This patch also sorts the #include blocks of all files that needed to be updated, according to the sorting suggestions from CODING_STYLE. Since pretty much every file needs our string manipulation functions this effectively means that most files have sorted #include blocks now. Also touches a few unrelated include files.

libsystemd-network: limit accuracy of timestamps in logging We don't care about timestamps down to the last usec, round to the closest sec as that will be plenty for debugging purposes.

sd-dhcp: fix namespacing Prefix all constants with SD_DHCP_CLIENT_* to avoid namespacing conflicts.

dhcp: don't underflow in lease time calculations Don't underflow when calculating lease time.

dhcp: NTP servers should be requested by networkd but not implicitly by sd-dhcp The library so far always requested the NTP servers. This might be unnecessary in some uses, hence let's move the request into networkd instead.

dhcp: clean up dhcp4 lease object a) drop handling of obsolete or unused DHCP options time_offset, mtu_aging_timeout, policy filter, mdr, ttl, ip forwarding settings. Should this become useful one day we can readd support for this. b) For subnet mask and broadcast it is not always clear whether 0 or 255.255.255.255 might be valid, hence maintain a boolean indicating validity next to it. c) serialize/deserialize broadcast address, lifetime, T1 and T2 together with the rest of the fields in dhcp_lease_save() and dhcp_lease_load(). d) consistently return ENODATA from getter functions for data that is missing in the lease. e) add missing getter calls for broadcast, lifetime, T1, T2. f) when decoding DHCP options, generate debug messages on parse failures, but try to proceed if possible. g) Similar, when deserializing a lease in dhcp_lease_load(), make sure we deal nicely with unparsable fields, to provide upgrade compat. h) fix some memory allocations

dhcp: stop using refcnt.h No need to invole atomic ops in single-threaded APIs, let's simplify this.

sd-dhcp: don't randomly ref objects In our API design, getter-functions don't ref objects. Calls like foo_get_bar() will not ref 'bar'. We never do that and there is no real reason to do it in single threaded APIs. If you need a ref-count, you better take it yourself *BEFORE* doing anything else on the parent object (as this might invalidate your pointer). Right now, sd_dhcp?_get_lease() refs the lease it returns. A lot of code-paths in systemd do not expect this and thus leak the lease reference. Fix this by changing the API to not ref returned objects.

sd-dhcp-client: readd deleted error check Seems to have been removed by mistake in: 9021bb9f935c93b516b10c88db2a212a9e3a8140

util: introduce CMSG_FOREACH() macro and make use of it everywhere It's only marginally shorter then the usual for() loop, but certainly more readable.

dhcp: yes, infiniband has the larger MAC address length, but let the compuler figure that out...

shared: add random-util.[ch]

Revert "sd-dhcp-client: fix strict aliasing issue" This reverts commit 6ec8e7c763b7dfa82e25e31f6938122748d1608f. This doesn't fix any issues, just makes the code harder to read.

sd-dhcp-client: fix strict aliasing issue

remove unused includes This patch removes includes that are not used. The removals were found with include-what-you-use which checks if any of the symbols from a header is in use.

Revert "tree-wide: Always use recvmsg with MSG_CMSG_CLOEXEC" This reverts commit d6d810fbf8071f8510450dbacd1d083f37603656. It's apparently not OK to pass MSG_CMSG_CLOEXEC to recvmsg() of raw sockets.

tree-wide: Always use recvmsg with MSG_CMSG_CLOEXEC

sd-dhcp-client: use RFC4361-complient ClientID by default In addition to the benefits listed in the RFC, this allows DHCP to work also in case several interfaces share the same MAC address on the same link (IPVLAN). Note that this will make the ClientID (so probably the assigned IP address) change on upgrades. If it is desired to avoid that we would have to remember and write back the ID (which the library supports, but networkd currently does not).

Assorted format fixes Types used for pids and uids in various interfaces are unpredictable. Too bad.

refcnt: refcnt is unsigned, fix comparisons This does not make a difference, but the code was confusing.

tree-wide: spelling fixes https://github.com/vlajos/misspell_fixer https://github.com/torstehu/systemd/commit/b6fdeb618cf2f3ce1645b3315f15f482710c7ffa Thanks to Torstein Husebo <torstein@huseboe.net>.

sd-dhcp-client: log if we fail to set up lease timers

sd-dhcp-lease: load/save client ID The lease is usually tied to the client ID, so users of the lease may want to know what client ID it was acquired with.

sd-dhcp-client: allow getting/setting the client ID The client identifier can be in many different formats, not just the one that systemd creates from the Ethernet MAC address. Non- ethernet interfaces may have different client IDs formats. Users may also have custom client IDs that the wish to use to preserve lease options delivered by servers configured with the existing client ID.

sd-dhcp-client: fix REBOOT state handling client->secs wasn't getting set in the REBOOT state, causing an assertion. REBOOT should work the same way as INIT, per RFC 2131: secs 2 Filled in by client, seconds elapsed since client began address acquisition or renewal process. REBOOT is necessary because some DHCP servers (eg on home routers) do not hand back the same IP address unless the 'ciaddr' field is filled with that address, which DISCOVER cannot do per the RFCs. This leads to multiple leases on machine reboot or DHCP client restart.

sd-event: rename sd_event_source_set_name() to sd_event_source_get_name() To mirror the recent name change of the concept for sd_bus objects, follow the same logic for sd_event_source objects, too.

sd-dhcp-client: clean up raw socket sd_event_source when creating new UDP socket The raw socket sd_event_source used for DHCP server solicitations was simply dropped on the floor when creating the new UDP socket after a lease has been acquired. Clean it up properly so we're not still listening and responding to events on it.

sd-dhcp-client: support non-Ethernet hardware addresses Like Infiniband. See RFC 4390 section 2.1 for details on DHCP and Infiniband; chaddr is zeroed, hlen is set to 0, and htype is set to ARPHRD_INFINIBAND because IB hardware addresses are 20 bytes in length.

Fix a few typos in log messages

sd-event: name event sources used in libraries This should help in debugging failing event sources.

util: never use ether_ntoa(), since it formats with %x, not %02x, which makes ethernet addresses look funny

sd-dhcp-client: allow the max dhcp message size to be set to the MTU of the link

sd-dhcp-client: add support for FORCERENEW This partially implements RFC3203. Note that we are not fully compliant as we do not support authentication.

sd-dhcp-client: listen on UDP socket as soon as a lease is acquired This is necessary in order to listen for FORCERENEW events.

sd-dhcp-client: drop event DHCP_EVENT_NO_LEASE Keep this internal to the client and simply restart it when NAK is receieved, as per the RFC.

sd-dhcp-client: only verify UDP messages RAW messages are verified by the BPF in the kernel.

libsystemd-network: use CLOCK_BOOTTIME instead of CLOCK_MONOTONIC where possible The timeouts in the networking library (DHCP lease timeouts and similar) should not be affected by suspend. In the cases where CLOCK_BOOTTIME is not implemented, it is still safe to fallback to CLOCK_MONOTONIC, as the consumers of the library (i.e., networkd) _should_ renew the leases when coming out of suspend.

sd-dhcp-client: make request broadcasts opt-in It appears there is no good way to decide whether or not broadcasts should be enabled, there is hardware that must have broadcast, and there are networks that only allow unicast. So we give up and make this configurable. By default, unicast is used, but if the kernel were to inform us abotu certain interfaces requiring broadcast, we could change this to opt-in by default in those cases.

networkd: dhcp add vendor class indentifier option 60 Vendor Class Identifier be used by DHCP clients to identify their vendor type and configuration. When using this option, vendors can define their own specific identifier values, such as to convey a particular hardware or operating system configuration or other identifying information. Vendor-specified DHCP options—features that let administrators assign separate options to clients with similar configuration requirements. For example, if DHCP-aware clients for example we want to separate different gateway and option for different set of people (dev/test/hr/finance) in a org or devices for example web/database servers or let's say in a embedded device etc and require a different default gateway or DNS server than the rest of clients.

dhcp-network: add check for DHCP.chaddr Check that received DHCP packets actually include our MAC address in chaddr field. BPF interpreter has 32 bit wide registers but MAC address is 48 bits long so we have to do check in two steps.

networkd: send hostname to dhcp server Send hostname (option 12) in DISCOVER and REQUEST messages so the DHCP server could use it to register with dynamic DNS and such. To opt-out of this behaviour set SendHostname to false in [DHCP] section of .network file [tomegun: rebased, made sure a failing set_hostname is a noop and moved config from DHCPv4 to DHCP]

sd-dhcp-client: don't fail hard if UDP socket can not be bound Even if we cannot renew the lease at T1, we will likely succeed at T2, so warn and ignore the failure. This could happen if for whatever reason the received address is not yet configured, or it has been lost.

sd-dhcp-client/networkd: set lifetimes for IPv4 addresses Note that /proc/sys/net/ipv4/ip_dynaddr needs to be non-zero. [tomegun: hook up DHCP renew events to increase the lifetime when necessary]

sd-dhcp-client: return NULL from _unref() like the other sd-* libraries Let's keep this behavior consistent across our libraries. In order to keep the refcounting working, a DONT_DESTROY macro similar to the one in sd-bus was introduced.

sd-dhcp-client: check return from dhcp_option_append

sd-dhcp-client: fix invalid free() in client_send_request() static int client_send_request(...) in ./src/libsystemd-network/sd-dhcp-client.c tries to initialize "request" by calling client_message_init(...), which has atleast 5 error cases where it can return without that happening. This leads to the function finishing without "request" being initialized.

sd-dhcp-client: allways request broadcast On systems which cannot receive unicast packets until its IP stack has been configured we need to request broadcast packets. We are currently not able to reliably detect when this is necessary, so set it unconditionally for now. This is set on all packets, but the DHCP server will only broadcast the packets that are necessary, and unicast the rest. For more information please refer to this thread in CoreOS: https://github.com/coreos/bugs/issues/12 [tomegun: rephrased commit message]

Use %m instead of strerror(errno) where appropiate

sd-dhcp-client: factor out dhcp packet allocation

sd-dhcp: rely on FIONREAD working This fallback will anyway never get tested, so rip it out.

sd-dhcp: option_append - support falling back to 'sname' and 'file'

sd-dhcp: refactor dhcp_option_append Store a pointer to the options in the DHCPMessage struct, and pass this together with an offset around, rather than a uint8_t**. This avoids us having to (re)compute the pointer; and changes dhcp_option_append from adjusting both the pointer to the next option and the remaining size of the options, to just adjusting the current offset. This makes the code a bit simpler to follow IMHO, but there should be no functional change.

sd-dhcp-client: improve logging when stopping client 'Requested by user' was confusing, just drop it.

sd-dhcp-client: use asynchronous_close() close() is a blocking call, which may slow things down measurably when running many dhcp clients in the same single-threaded main loop. Let's just use the asynchronous version instead to avoid the problem.

dhcp-network: don't pass ifindex to bind_udp_socket UDP sockets can anyway not be bound to specific netdev's. The packages would have to be filtered when received instead.

sd-dhcp-client: log positive error number Log error no for such client_stop(client, DHCP_EVENT_STOP)

libnetworkd: add link local tests - Also only allow positive ifindex on both dhcp and ipv4ll [tomegun: the kernel always sets a positive ifindex, but some APIs accept ifindex=0 with various meanings, so we should protect against accidentally passing ifindex=0 along.]

sd-dhcp-client: log ifindex and mac address when starting

test-dhcp-client: unref lease objects to make valgrind happy Also unref client objects in test code, and initalize logging, to DEBUG by default.

sd-dhcp-client: drop logging about T1/T2 These are redundant now that the REQUEST messages contain the same information.

sd-dhcp-client: improve logging Specify what kind of REQUEST we send, and distinguish between REBOOT and START. Also log stop reasons as strings rather than numbers.

sd-dhcp-client: use client_initialiez and client_restart for REBOOT

sd-dhcp-client: document message creation a bit more Also reshuffle some code to make the correspondence with the RFC a bit more obvious. Small functional change: fail if we try to send a message from the wrong state.

sd-dhcp-client: assert that we can only create DISCOVER or REQUEST messages

sd-dhcp-client: rebind raw socket when resetting transaction id As we are now filtering the raw socket based on the transaction id, we must reset the BPF when we reset the transaction id.

sd-dhcp-client: Add an explicit stop state for the DHCP client Add an explicit stop state for the DHCP client so that the library user can issue a stop at any time the callback has been called. When returning from the callback, check also the stop state and stop any further DHCP processing.

sd-dhcp-client: Add reference counting for DHCP The DHCP library user can decide to free the DHCP client any time the callback is called. After the callback has been called, other computations may still be needed - the best example being a full restart of the DHCP procedure in case of lease expiry. Fix this by introducing proper reference counting. Properly handle a returned NULL from the notify and stop functions if the DHCP client was freed.

sd-dhcp-client: recevie_message - verify cmsg_len before reading

sd-dhcp-client: improve BPF Try a bit harder to make the kernel drop packets not for us. This should reduce the number of wakeups from n^2 to n in the number of dhcp clients, which admittedly only makes a differenc in very extreme cases.

sd-dhcp-client: eagerly drop too small packets If they are too small to fit the IP+UDP+DHCP headers they can be of no use, so don't waste resources parsing them. This is at the cost of losing some verbosity in the logging.

sd-dhcp-client: move magic cookie into DHCPMessage struct Also move the checking of it to the main message handler, rather than the options parser. Fix a bug, so we now drop the packet if any of the magic bytes don't match. Before we used to only drop the packet if they were all wrong.

silence warnings

sd-event: rework API to support CLOCK_REALTIME_ALARM and CLOCK_BOOTTIME_ALARM, too

sd-dhcp-client/sd-ipv4ll: allow mac address to be updated at any time If necessary, restart the clients to deal with a changing mac address at runtime. This will solve the problem of starting clients on bridges before they have received their final MAC address.

sd-dhcp-client: add fallback subnet masks The DHCP RFC does not require the DHCP server to send a subnet mask, so if it is missing, let's try to use the default subnet masks based on address class. In case the class the address belongs to does not have a default subnet mask, we fail as before. Also improve logging when handling invalid dhcp messages, and simply ignore them rather than stop the whole dhcp client.

sd-dhcp-client: make timeout handling a bit more robust Accept any lease lifetime greater than one second. Server should not hand out extremely short leases, but let's not be the ones to fail. Do not fail when arming a timer in the past, but also only arm one such timer. Avoid rounding errors when computing the default timeouts, this may be an issue if we are handed a very short lease. Also, don't pass 'time_now' around, as that can be found in the event object when needed.

sd-dhcp-client: do not reset 'secs' when entering INIT-REBOOT Also keep start_time in sync, but that shouldn't matter.

sd-dhcp-client: don't pass around 'secs' The value is stored in the client object, so get it there when needed.

libsystemd-network: Don't unnecessarily send too long packets Since the length used by options is known, send packets with no extra padding.

libsystemd-network: Prepend hardware type byte to client identifier Even though client identifiers SHOULD be treated as opaque objects by DHCP servers, follow the recommendation of a hardware type field with value 0x01 (ethernet) followed by the hardware address as described in RFC 2132.

sd-dhcp-client: accept infinite lease lifetime Otherwise we would fail with -EINVAL. Thanks to Brandon Philips <brandon.philips@coreos.com>, for reporting the bug.

libsystemd-network: Add Init-Reboot support Init-Reboot is tried if a client IP address has been given when the DHCP client is started. In Init-Reboot, start by sending a broadcast DHCP Request including the supplied client IP address but without the server identifier. After sending the request, enter Reboot state. If a DHCP Ack is received, proceed to Bound state as usual. If a DHCP Nak is received or the first timeout triggers, start the address acquisition over from DHCP Init state. See RFC 2131, sections 4.3.2, 4.4, 4.4.1 and 4.4.2 for details.

libsystemd-network: Restart DHCP acquisition if the lease expires This causes the DHCP client struct initialization and DHCP client starting to be factored out into functions of their own.

util: replace close_nointr_nofail() by a more useful safe_close() safe_close() automatically becomes a NOP when a negative fd is passed, and returns -1 unconditionally. This makes it easy to write lines like this: fd = safe_close(fd); Which will close an fd if it is open, and reset the fd variable correctly. By making use of this new scheme we can drop a > 200 lines of code that was required to test for non-negative fds or to reset the closed fd variable afterwards.

sd-dhcp-client: make sure timers fire immediately The default slack caused there to be a delay before timers fired. Solve it by setting timers that should trigger immediately to trigger far in the past. This brings down the ideal-case dhcp lease acquisition time from about 500ms to about 50ms (over a veth pair, so no network latency involved). All the rest of the time (except for ~0.5ms) is spent in the bind() call in, dhcp_network_bind_raw_socket(). I don't know if there is anything to be done about that though...

sd-dhcp-client: use close_nointr_nofail() We are already assuming the close() will not fail, so make it explicit.

sd-dhcp: generalise ip header generation This will be needed for sd-dhcp-server.

sd-dhcp-client: log the MAC address we are using

sd-dhcp-lease: add sd_dhcp_lease_get_next_server()

sd-network: add new library This is similar to sd-login, but exposes the state of networkd rather than logind. Include it in libsystemd-dhcp and rename it to libsystemd-network.