Merge pull request #1288 from teg/ipv4acd-3

sd-ipv4acd: split out as separate library from sd-ipv4ll

1 files changed, 162 insertions, 479 deletions

diff --git a/src/libsystemd-network/sd-ipv4ll.c b/src/libsystemd-network/sd-ipv4ll.c
index 14b9444dab..f0230b919c 100644
--- a/src/libsystemd-network/sd-ipv4ll.c
+++ b/src/libsystemd-network/sd-ipv4ll.c
@@ -2,6 +2,7 @@
   This file is part of systemd.
 
   Copyright (C) 2014 Axis Communications AB. All rights reserved.
+  Copyright (C) 2015 Tom Gundersen
 
   systemd is free software; you can redistribute it and/or modify it
   under the terms of the GNU Lesser General Public License as published by
@@ -23,429 +24,153 @@
 #include <stdio.h>
 #include <arpa/inet.h>
 
-#include "util.h"
-#include "siphash24.h"
+#include "event-util.h"
 #include "list.h"
 #include "random-util.h"
+#include "refcnt.h"
+#include "siphash24.h"
+#include "sparse-endian.h"
+#include "util.h"
 
-#include "ipv4ll-internal.h"
+#include "sd-ipv4acd.h"
 #include "sd-ipv4ll.h"
 
-/* Constants from the RFC */
-#define PROBE_WAIT 1
-#define PROBE_NUM 3
-#define PROBE_MIN 1
-#define PROBE_MAX 2
-#define ANNOUNCE_WAIT 2
-#define ANNOUNCE_NUM 2
-#define ANNOUNCE_INTERVAL 2
-#define MAX_CONFLICTS 10
-#define RATE_LIMIT_INTERVAL 60
-#define DEFEND_INTERVAL 10
-
 #define IPV4LL_NETWORK 0xA9FE0000L
 #define IPV4LL_NETMASK 0xFFFF0000L
 
-typedef enum IPv4LLTrigger{
-        IPV4LL_TRIGGER_NULL,
-        IPV4LL_TRIGGER_PACKET,
-        IPV4LL_TRIGGER_TIMEOUT,
-        _IPV4LL_TRIGGER_MAX,
-        _IPV4LL_TRIGGER_INVALID = -1
-} IPv4LLTrigger;
-
-typedef enum IPv4LLState {
-        IPV4LL_STATE_INIT,
-        IPV4LL_STATE_WAITING_PROBE,
-        IPV4LL_STATE_PROBING,
-        IPV4LL_STATE_WAITING_ANNOUNCE,
-        IPV4LL_STATE_ANNOUNCING,
-        IPV4LL_STATE_RUNNING,
-        IPV4LL_STATE_STOPPED,
-        _IPV4LL_STATE_MAX,
-        _IPV4LL_STATE_INVALID = -1
-} IPv4LLState;
+#define IPV4LL_DONT_DESTROY(ll) \
+        _cleanup_ipv4ll_unref_ _unused_ sd_ipv4ll *_dont_destroy_##ll = sd_ipv4ll_ref(ll)
 
 struct sd_ipv4ll {
         unsigned n_ref;
 
-        IPv4LLState state;
-        int index;
-        int fd;
-        union sockaddr_union link;
-        int iteration;
-        int conflict;
-        sd_event_source *receive_message;
-        sd_event_source *timer;
-        usec_t next_wakeup;
-        usec_t defend_window;
-        int next_wakeup_valid;
-        be32_t address;
+        sd_ipv4acd *acd;
+        be32_t address; /* the address pushed to ACD */
         struct random_data *random_data;
         char *random_data_state;
+
         /* External */
         be32_t claimed_address;
-        struct ether_addr mac_addr;
-        sd_event *event;
-        int event_priority;
         sd_ipv4ll_cb_t cb;
         void* userdata;
 };
 
-static void ipv4ll_run_state_machine(sd_ipv4ll *ll, IPv4LLTrigger trigger, void *trigger_data);
-
-static void ipv4ll_set_state(sd_ipv4ll *ll, IPv4LLState st, int reset_counter) {
-
-        assert(ll);
-        assert(st < _IPV4LL_STATE_MAX);
-
-        if (st == ll->state && !reset_counter) {
-                ll->iteration++;
-        } else {
-                ll->state = st;
-                ll->iteration = 0;
-        }
-}
-
-static sd_ipv4ll *ipv4ll_client_notify(sd_ipv4ll *ll, int event) {
-        assert(ll);
-
-        if (ll->cb) {
-                ll = sd_ipv4ll_ref(ll);
-                ll->cb(ll, event, ll->userdata);
-                ll = sd_ipv4ll_unref(ll);
-        }
-
-        return ll;
-}
-
-static sd_ipv4ll *ipv4ll_stop(sd_ipv4ll *ll, int event) {
-        assert(ll);
-
-        ll->receive_message = sd_event_source_unref(ll->receive_message);
-        ll->fd = safe_close(ll->fd);
-
-        ll->timer = sd_event_source_unref(ll->timer);
-
-        log_ipv4ll(ll, "STOPPED");
-
-        ll = ipv4ll_client_notify(ll, event);
+sd_ipv4ll *sd_ipv4ll_ref(sd_ipv4ll *ll) {
+        if (!ll)
+                return NULL;
 
-        if (ll) {
-                ll->claimed_address = 0;
-                ipv4ll_set_state (ll, IPV4LL_STATE_INIT, 1);
-        }
+        assert(ll->n_ref >= 1);
+        ll->n_ref++;
 
         return ll;
 }
 
-static int ipv4ll_pick_address(sd_ipv4ll *ll, be32_t *address) {
-        be32_t addr;
-        int r;
-        int32_t random;
-
-        assert(ll);
-        assert(address);
-        assert(ll->random_data);
-
-        do {
-                r = random_r(ll->random_data, &random);
-                if (r < 0)
-                        return r;
-                addr = htonl((random & 0x0000FFFF) | IPV4LL_NETWORK);
-        } while (addr == ll->address ||
-                (ntohl(addr) & IPV4LL_NETMASK) != IPV4LL_NETWORK ||
-                (ntohl(addr) & 0x0000FF00) == 0x0000 ||
-                (ntohl(addr) & 0x0000FF00) == 0xFF00);
-
-        *address = addr;
-        return 0;
-}
-
-static int ipv4ll_timer(sd_event_source *s, uint64_t usec, void *userdata) {
-        sd_ipv4ll *ll = (sd_ipv4ll*)userdata;
-
-        assert(ll);
-
-        ll->next_wakeup_valid = 0;
-        ipv4ll_run_state_machine(ll, IPV4LL_TRIGGER_TIMEOUT, NULL);
-
-        return 0;
-}
-
-static void ipv4ll_set_next_wakeup(sd_ipv4ll *ll, int sec, int random_sec) {
-        usec_t next_timeout = 0;
-        usec_t time_now = 0;
-
-        assert(sec >= 0);
-        assert(random_sec >= 0);
-        assert(ll);
-
-        next_timeout = sec * USEC_PER_SEC;
-
-        if (random_sec)
-                next_timeout += random_u32() % (random_sec * USEC_PER_SEC);
-
-        assert_se(sd_event_now(ll->event, clock_boottime_or_monotonic(), &time_now) >= 0);
-
-        ll->next_wakeup = time_now + next_timeout;
-        ll->next_wakeup_valid = 1;
-}
-
-static bool ipv4ll_arp_conflict (sd_ipv4ll *ll, struct ether_arp *arp) {
-        assert(ll);
-        assert(arp);
-
-        if (memcmp(arp->arp_spa, &ll->address, sizeof(ll->address)) == 0 &&
-            memcmp(arp->arp_sha, &ll->mac_addr, ETH_ALEN) != 0)
-                return true;
+sd_ipv4ll *sd_ipv4ll_unref(sd_ipv4ll *ll) {
+        if (!ll)
+                return NULL;
 
-        return false;
-}
+        assert(ll->n_ref >= 1);
+        ll->n_ref--;
 
-static bool ipv4ll_arp_probe_conflict (sd_ipv4ll *ll, struct ether_arp *arp) {
-        assert(ll);
-        assert(arp);
+        if (ll->n_ref > 0)
+                return NULL;
 
-        if (ipv4ll_arp_conflict(ll, arp))
-                return true;
+        sd_ipv4acd_unref(ll->acd);
 
-        if (memcmp(arp->arp_tpa, &ll->address, sizeof(ll->address)) == 0 &&
-            memcmp(arp->arp_sha, &ll->mac_addr, ETH_ALEN))
-                return true;
+        free(ll->random_data);
+        free(ll->random_data_state);
+        free(ll);
 
-        return false;
+        return NULL;
 }
 
-static void ipv4ll_run_state_machine(sd_ipv4ll *ll, IPv4LLTrigger trigger, void *trigger_data) {
-        struct ether_arp out_packet;
-        int out_packet_ready = 0;
-        int r = 0;
-
-        assert(ll);
-        assert(trigger < _IPV4LL_TRIGGER_MAX);
-
-        if (ll->state == IPV4LL_STATE_INIT) {
-
-                log_ipv4ll(ll, "PROBE");
-                ipv4ll_set_state(ll, IPV4LL_STATE_WAITING_PROBE, 1);
-                ipv4ll_set_next_wakeup(ll, 0, PROBE_WAIT);
-
-        } else if ((ll->state == IPV4LL_STATE_WAITING_PROBE && trigger == IPV4LL_TRIGGER_TIMEOUT) ||
-                (ll->state == IPV4LL_STATE_PROBING && trigger == IPV4LL_TRIGGER_TIMEOUT && ll->iteration < PROBE_NUM-2)) {
-
-                /* Send a probe */
-                arp_packet_probe(&out_packet, ll->address, &ll->mac_addr);
-                out_packet_ready = 1;
-                ipv4ll_set_state(ll, IPV4LL_STATE_PROBING, 0);
-
-                ipv4ll_set_next_wakeup(ll, PROBE_MIN, (PROBE_MAX-PROBE_MIN));
-
-        } else if (ll->state == IPV4LL_STATE_PROBING && trigger == IPV4LL_TRIGGER_TIMEOUT && ll->iteration >= PROBE_NUM-2) {
-
-                /* Send the last probe */
-                arp_packet_probe(&out_packet, ll->address, &ll->mac_addr);
-                out_packet_ready = 1;
-                ipv4ll_set_state(ll, IPV4LL_STATE_WAITING_ANNOUNCE, 1);
-
-                ipv4ll_set_next_wakeup(ll, ANNOUNCE_WAIT, 0);
-
-        } else if ((ll->state == IPV4LL_STATE_WAITING_ANNOUNCE && trigger == IPV4LL_TRIGGER_TIMEOUT) ||
-                (ll->state == IPV4LL_STATE_ANNOUNCING && trigger == IPV4LL_TRIGGER_TIMEOUT && ll->iteration < ANNOUNCE_NUM-1)) {
-
-                /* Send announcement packet */
-                arp_packet_announcement(&out_packet, ll->address, &ll->mac_addr);
-                out_packet_ready = 1;
-                ipv4ll_set_state(ll, IPV4LL_STATE_ANNOUNCING, 0);
-
-                ipv4ll_set_next_wakeup(ll, ANNOUNCE_INTERVAL, 0);
-
-                if (ll->iteration == 0) {
-                        log_ipv4ll(ll, "ANNOUNCE");
-                        ll->claimed_address = ll->address;
-                        ll = ipv4ll_client_notify(ll, IPV4LL_EVENT_BIND);
-                        if (!ll || ll->state == IPV4LL_STATE_STOPPED)
-                                goto out;
-
-                        ll->conflict = 0;
-                }
-
-        } else if ((ll->state == IPV4LL_STATE_ANNOUNCING && trigger == IPV4LL_TRIGGER_TIMEOUT &&
-                    ll->iteration >= ANNOUNCE_NUM-1)) {
-
-                ipv4ll_set_state(ll, IPV4LL_STATE_RUNNING, 0);
-                ll->next_wakeup_valid = 0;
-
-        } else if (trigger == IPV4LL_TRIGGER_PACKET) {
-
-                int conflicted = 0;
-                usec_t time_now;
-                struct ether_arp* in_packet = (struct ether_arp*)trigger_data;
-
-                assert(in_packet);
-
-                if (IN_SET(ll->state, IPV4LL_STATE_ANNOUNCING, IPV4LL_STATE_RUNNING)) {
-
-                        if (ipv4ll_arp_conflict(ll, in_packet)) {
-
-                                r = sd_event_now(ll->event, clock_boottime_or_monotonic(), &time_now);
-                                if (r < 0)
-                                        goto out;
-
-                                /* Defend address */
-                                if (time_now > ll->defend_window) {
-                                        ll->defend_window = time_now + DEFEND_INTERVAL * USEC_PER_SEC;
-                                        arp_packet_announcement(&out_packet, ll->address, &ll->mac_addr);
-                                        out_packet_ready = 1;
-                                } else
-                                        conflicted = 1;
-                        }
-
-                } else if (IN_SET(ll->state, IPV4LL_STATE_WAITING_PROBE,
-                                             IPV4LL_STATE_PROBING,
-                                             IPV4LL_STATE_WAITING_ANNOUNCE)) {
-
-                        conflicted = ipv4ll_arp_probe_conflict(ll, in_packet);
-                }
-
-                if (conflicted) {
-                        log_ipv4ll(ll, "CONFLICT");
-                        ll = ipv4ll_client_notify(ll, IPV4LL_EVENT_CONFLICT);
-                        if (!ll || ll->state == IPV4LL_STATE_STOPPED)
-                                goto out;
+DEFINE_TRIVIAL_CLEANUP_FUNC(sd_ipv4ll*, sd_ipv4ll_unref);
+#define _cleanup_ipv4ll_unref_ _cleanup_(sd_ipv4ll_unrefp)
 
-                        ll->claimed_address = 0;
+static void ipv4ll_on_acd(sd_ipv4acd *ll, int event, void *userdata);
 
-                        /* Pick a new address */
-                        r = ipv4ll_pick_address(ll, &ll->address);
-                        if (r < 0)
-                                goto out;
-                        ll->conflict++;
-                        ll->defend_window = 0;
-                        ipv4ll_set_state(ll, IPV4LL_STATE_WAITING_PROBE, 1);
+int sd_ipv4ll_new(sd_ipv4ll **ret) {
+        _cleanup_ipv4ll_unref_ sd_ipv4ll *ll = NULL;
+        int r;
 
-                        if (ll->conflict >= MAX_CONFLICTS) {
-                                log_ipv4ll(ll, "MAX_CONFLICTS");
-                                ipv4ll_set_next_wakeup(ll, RATE_LIMIT_INTERVAL, PROBE_WAIT);
-                        } else
-                                ipv4ll_set_next_wakeup(ll, 0, PROBE_WAIT);
+        assert_return(ret, -EINVAL);
 
-                }
-        }
+        ll = new0(sd_ipv4ll, 1);
+        if (!ll)
+                return -ENOMEM;
 
-        if (out_packet_ready) {
-                r = arp_network_send_raw_socket(ll->fd, &ll->link, &out_packet);
-                if (r < 0) {
-                        log_ipv4ll(ll, "failed to send arp packet out");
-                        goto out;
-                }
-        }
+        r = sd_ipv4acd_new(&ll->acd);
+        if (r < 0)
+                return r;
 
-        if (ll->next_wakeup_valid) {
-                ll->timer = sd_event_source_unref(ll->timer);
-                r = sd_event_add_time(ll->event, &ll->timer, clock_boottime_or_monotonic(),
-                                      ll->next_wakeup, 0, ipv4ll_timer, ll);
-                if (r < 0)
-                        goto out;
+        r = sd_ipv4acd_set_callback(ll->acd, ipv4ll_on_acd, ll);
+        if (r < 0)
+                return r;
 
-                r = sd_event_source_set_priority(ll->timer, ll->event_priority);
-                if (r < 0)
-                        goto out;
+        ll->n_ref = 1;
 
-                r = sd_event_source_set_description(ll->timer, "ipv4ll-timer");
-                if (r < 0)
-                        goto out;
-        }
+        *ret = ll;
+        ll = NULL;
 
-out:
-        if (r < 0 && ll)
-                ipv4ll_stop(ll, r);
+        return 0;
 }
 
-static int ipv4ll_receive_message(sd_event_source *s, int fd,
-                                  uint32_t revents, void *userdata) {
+int sd_ipv4ll_stop(sd_ipv4ll *ll) {
         int r;
-        struct ether_arp arp;
-        sd_ipv4ll *ll = (sd_ipv4ll*)userdata;
 
-        assert(ll);
-
-        r = read(fd, &arp, sizeof(struct ether_arp));
-        if (r < (int) sizeof(struct ether_arp))
-                return 0;
+        assert_return(ll, -EINVAL);
 
-        r = arp_packet_verify_headers(&arp);
+        r = sd_ipv4acd_stop(ll->acd);
         if (r < 0)
-                return 0;
-
-        ipv4ll_run_state_machine(ll, IPV4LL_TRIGGER_PACKET, &arp);
+                return r;
 
         return 0;
 }
 
 int sd_ipv4ll_set_index(sd_ipv4ll *ll, int interface_index) {
         assert_return(ll, -EINVAL);
-        assert_return(interface_index > 0, -EINVAL);
-        assert_return(IN_SET(ll->state, IPV4LL_STATE_INIT,
-                             IPV4LL_STATE_STOPPED), -EBUSY);
 
-        ll->index = interface_index;
-
-        return 0;
+        return sd_ipv4acd_set_index(ll->acd, interface_index);
 }
 
+#define HASH_KEY SD_ID128_MAKE(df,04,22,98,3f,ad,14,52,f9,87,2e,d1,9c,70,e2,f2)
+
 int sd_ipv4ll_set_mac(sd_ipv4ll *ll, const struct ether_addr *addr) {
-        bool need_restart = false;
+        int r;
 
         assert_return(ll, -EINVAL);
-        assert_return(addr, -EINVAL);
-
-        if (memcmp(&ll->mac_addr, addr, ETH_ALEN) == 0)
-                return 0;
 
-        if (!IN_SET(ll->state, IPV4LL_STATE_INIT, IPV4LL_STATE_STOPPED)) {
-                log_ipv4ll(ll, "Changing MAC address on running IPv4LL "
-                           "client, restarting");
-                ll = ipv4ll_stop(ll, IPV4LL_EVENT_STOP);
-                need_restart = true;
-        }
+        if (!ll->random_data) {
+                uint8_t seed[8];
 
-        if (!ll)
-                return 0;
+                /* If no random data is set, generate some from the MAC */
+                siphash24(seed, &addr->ether_addr_octet,
+                          ETH_ALEN, HASH_KEY.bytes);
 
-        memcpy(&ll->mac_addr, addr, ETH_ALEN);
+                assert_cc(sizeof(unsigned) <= 8);
 
-        if (need_restart)
-                sd_ipv4ll_start(ll);
+                r = sd_ipv4ll_set_address_seed(ll, *(unsigned*)seed);
+                if (r < 0)
+                        return r;
+        }
 
-        return 0;
+        return sd_ipv4acd_set_mac(ll->acd, addr);
 }
 
 int sd_ipv4ll_detach_event(sd_ipv4ll *ll) {
         assert_return(ll, -EINVAL);
 
-        ll->event = sd_event_unref(ll->event);
-
-        return 0;
+        return sd_ipv4acd_detach_event(ll->acd);
 }
 
 int sd_ipv4ll_attach_event(sd_ipv4ll *ll, sd_event *event, int priority) {
         int r;
 
         assert_return(ll, -EINVAL);
-        assert_return(!ll->event, -EBUSY);
-
-        if (event)
-                ll->event = sd_event_ref(event);
-        else {
-                r = sd_event_default(&ll->event);
-                if (r < 0) {
-                        ipv4ll_stop(ll, IPV4LL_EVENT_STOP);
-                        return r;
-                }
-        }
 
-        ll->event_priority = priority;
+        r = sd_ipv4acd_attach_event(ll->acd, event, priority);
+        if (r < 0)
+                return r;
 
         return 0;
 }
@@ -467,189 +192,147 @@ int sd_ipv4ll_get_address(sd_ipv4ll *ll, struct in_addr *address){
                 return -ENOENT;
 
         address->s_addr = ll->claimed_address;
+
         return 0;
 }
 
-int sd_ipv4ll_set_address_seed (sd_ipv4ll *ll, uint8_t seed[8]) {
-        unsigned int entropy;
+int sd_ipv4ll_set_address_seed(sd_ipv4ll *ll, unsigned seed) {
+        _cleanup_free_ struct random_data *random_data = NULL;
+        _cleanup_free_ char *random_data_state = NULL;
         int r;
 
         assert_return(ll, -EINVAL);
         assert_return(seed, -EINVAL);
 
-        entropy = *seed;
+        random_data = new0(struct random_data, 1);
+        if (!random_data)
+                return -ENOMEM;
 
-        free(ll->random_data);
-        free(ll->random_data_state);
+        random_data_state = new0(char, 128);
+        if (!random_data_state)
+                return -ENOMEM;
 
-        ll->random_data = new0(struct random_data, 1);
-        ll->random_data_state = new0(char, 128);
+        r = initstate_r(seed, random_data_state, 128, random_data);
+        if (r < 0)
+                return r;
 
-        if (!ll->random_data || !ll->random_data_state) {
-                r = -ENOMEM;
-                goto error;
-        }
+        free(ll->random_data);
+        ll->random_data = random_data;
+        random_data = NULL;
 
-        r = initstate_r((unsigned int)entropy, ll->random_data_state, 128, ll->random_data);
-        if (r < 0)
-                goto error;
+        free(ll->random_data_state);
+        ll->random_data_state = random_data_state;
+        random_data_state = NULL;
 
-error:
-        if (r < 0){
-                free(ll->random_data);
-                free(ll->random_data_state);
-                ll->random_data = NULL;
-                ll->random_data_state = NULL;
-        }
-        return r;
+        return 0;
 }
 
 bool sd_ipv4ll_is_running(sd_ipv4ll *ll) {
         assert_return(ll, false);
 
-        return !IN_SET(ll->state, IPV4LL_STATE_INIT, IPV4LL_STATE_STOPPED);
+        return sd_ipv4acd_is_running(ll->acd);
 }
 
-#define HASH_KEY SD_ID128_MAKE(df,04,22,98,3f,ad,14,52,f9,87,2e,d1,9c,70,e2,f2)
-
-int sd_ipv4ll_start (sd_ipv4ll *ll) {
+static int ipv4ll_pick_address(sd_ipv4ll *ll) {
+        struct in_addr in_addr;
+        be32_t addr;
         int r;
+        int32_t random;
 
-        assert_return(ll, -EINVAL);
-        assert_return(ll->event, -EINVAL);
-        assert_return(ll->index > 0, -EINVAL);
-        assert_return(IN_SET(ll->state, IPV4LL_STATE_INIT,
-                             IPV4LL_STATE_STOPPED), -EBUSY);
+        assert(ll);
+        assert(ll->random_data);
 
-        ll->state = IPV4LL_STATE_INIT;
+        do {
+                r = random_r(ll->random_data, &random);
+                if (r < 0)
+                        return r;
+                addr = htonl((random & 0x0000FFFF) | IPV4LL_NETWORK);
+        } while (addr == ll->address ||
+                (ntohl(addr) & IPV4LL_NETMASK) != IPV4LL_NETWORK ||
+                (ntohl(addr) & 0x0000FF00) == 0x0000 ||
+                (ntohl(addr) & 0x0000FF00) == 0xFF00);
 
-        r = arp_network_bind_raw_socket(ll->index, &ll->link);
+        in_addr.s_addr = addr;
 
+        r = sd_ipv4acd_set_address(ll->acd, &in_addr);
         if (r < 0)
-                goto out;
+                return r;
 
-        ll->fd = r;
-        ll->conflict = 0;
-        ll->defend_window = 0;
-        ll->claimed_address = 0;
+        ll->address = addr;
 
-        if (!ll->random_data) {
-                uint8_t seed[8];
+        return 0;
+}
 
-                /* Fallback to mac */
-                siphash24(seed, &ll->mac_addr.ether_addr_octet,
-                          ETH_ALEN, HASH_KEY.bytes);
+int sd_ipv4ll_start(sd_ipv4ll *ll) {
+        int r;
 
-                r = sd_ipv4ll_set_address_seed(ll, seed);
-                if (r < 0)
-                        goto out;
-        }
+        assert_return(ll, -EINVAL);
+        assert_return(ll->random_data, -EINVAL);
 
         if (ll->address == 0) {
-                r = ipv4ll_pick_address(ll, &ll->address);
+                r = ipv4ll_pick_address(ll);
                 if (r < 0)
-                        goto out;
+                        return r;
         }
 
-        ipv4ll_set_state (ll, IPV4LL_STATE_INIT, 1);
-
-        r = sd_event_add_io(ll->event, &ll->receive_message, ll->fd,
-                            EPOLLIN, ipv4ll_receive_message, ll);
+        r = sd_ipv4acd_start(ll->acd);
         if (r < 0)
-                goto out;
-
-        r = sd_event_source_set_priority(ll->receive_message, ll->event_priority);
-        if (r < 0)
-                goto out;
-
-        r = sd_event_source_set_description(ll->receive_message, "ipv4ll-receive-message");
-        if (r < 0)
-                goto out;
-
-        r = sd_event_add_time(ll->event,
-                              &ll->timer,
-                              clock_boottime_or_monotonic(),
-                              now(clock_boottime_or_monotonic()), 0,
-                              ipv4ll_timer, ll);
-
-        if (r < 0)
-                goto out;
-
-        r = sd_event_source_set_priority(ll->timer, ll->event_priority);
-        if (r < 0)
-                goto out;
-
-        r = sd_event_source_set_description(ll->timer, "ipv4ll-timer");
-out:
-        if (r < 0)
-                ipv4ll_stop(ll, IPV4LL_EVENT_STOP);
+                return r;
 
         return 0;
 }
 
-int sd_ipv4ll_stop(sd_ipv4ll *ll) {
-        ipv4ll_stop(ll, IPV4LL_EVENT_STOP);
-        if (ll)
-                ipv4ll_set_state(ll, IPV4LL_STATE_STOPPED, 1);
-
-        return 0;
-}
-
-sd_ipv4ll *sd_ipv4ll_ref(sd_ipv4ll *ll) {
-
-        if (!ll)
-                return NULL;
-
-        assert(ll->n_ref >= 1);
-        ll->n_ref++;
+static void ipv4ll_client_notify(sd_ipv4ll *ll, int event) {
+        assert(ll);
 
-        return ll;
+        if (ll->cb)
+                ll->cb(ll, event, ll->userdata);
 }
 
-sd_ipv4ll *sd_ipv4ll_unref(sd_ipv4ll *ll) {
-
-        if (!ll)
-                return NULL;
-
-        assert(ll->n_ref >= 1);
-        ll->n_ref--;
-
-        if (ll->n_ref > 0)
-                return ll;
-
-        ll->receive_message = sd_event_source_unref(ll->receive_message);
-        ll->fd = safe_close(ll->fd);
-
-        ll->timer = sd_event_source_unref(ll->timer);
+void ipv4ll_on_acd(sd_ipv4acd *acd, int event, void *userdata) {
+        sd_ipv4ll *ll = userdata;
+        IPV4LL_DONT_DESTROY(ll);
+        int r;
 
-        sd_ipv4ll_detach_event(ll);
+        assert(acd);
+        assert(ll);
 
-        free(ll->random_data);
-        free(ll->random_data_state);
-        free(ll);
+        switch (event) {
+        case IPV4ACD_EVENT_STOP:
+                ipv4ll_client_notify(ll, IPV4LL_EVENT_STOP);
 
-        return NULL;
-}
+                ll->claimed_address = 0;
 
-DEFINE_TRIVIAL_CLEANUP_FUNC(sd_ipv4ll*, sd_ipv4ll_unref);
-#define _cleanup_ipv4ll_free_ _cleanup_(sd_ipv4ll_unrefp)
+                break;
+        case IPV4ACD_EVENT_BIND:
+                ll->claimed_address = ll->address;
+                ipv4ll_client_notify(ll, IPV4LL_EVENT_BIND);
 
-int sd_ipv4ll_new(sd_ipv4ll **ret) {
-        _cleanup_ipv4ll_free_ sd_ipv4ll *ll = NULL;
+                break;
+        case IPV4ACD_EVENT_CONFLICT:
+                /* if an address was already bound we must call up to the
+                   user to handle this, otherwise we just try again */
+                if (ll->claimed_address != 0) {
+                        ipv4ll_client_notify(ll, IPV4LL_EVENT_CONFLICT);
 
-        assert_return(ret, -EINVAL);
+                        ll->claimed_address = 0;
+                } else {
+                        r = ipv4ll_pick_address(ll);
+                        if (r < 0)
+                                goto error;
 
-        ll = new0(sd_ipv4ll, 1);
-        if (!ll)
-                return -ENOMEM;
+                        r = sd_ipv4acd_start(ll->acd);
+                        if (r < 0)
+                                goto error;
+                }
 
-        ll->n_ref = 1;
-        ll->state = IPV4LL_STATE_INIT;
-        ll->index = -1;
-        ll->fd = -1;
+                break;
+        default:
+                assert_not_reached("Invalid IPv4ACD event.");
+        }
 
-        *ret = ll;
-        ll = NULL;
+        return;
 
-        return 0;
+error:
+        ipv4ll_client_notify(ll, IPV4LL_EVENT_STOP);
 }