Merge pull request #1288 from teg/ipv4acd-3

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

13 files changed, 1212 insertions, 710 deletions

diff --git a/Makefile.am b/Makefile.am
index c395840759..3b35083d0a 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -1367,7 +1367,9 @@ manual_tests += \
 	test-watchdog \
 	test-log \
 	test-ipcrm \
-	test-btrfs
+	test-btrfs \
+	test-acd \
+	test-ipv4ll-manual
 
 if HAVE_LIBIPTC
 manual_tests += \
@@ -3198,6 +3200,7 @@ libsystemd_network_la_SOURCES = \
 	src/systemd/sd-dhcp-server.h \
 	src/systemd/sd-dhcp-lease.h \
 	src/systemd/sd-ipv4ll.h \
+	src/systemd/sd-ipv4acd.h \
 	src/systemd/sd-icmp6-nd.h \
 	src/systemd/sd-dhcp6-client.h \
 	src/systemd/sd-dhcp6-lease.h \
@@ -3214,9 +3217,9 @@ libsystemd_network_la_SOURCES = \
 	src/libsystemd-network/dhcp-lease-internal.h \
 	src/libsystemd-network/sd-dhcp-lease.c \
 	src/libsystemd-network/sd-ipv4ll.c \
-	src/libsystemd-network/ipv4ll-network.c \
-	src/libsystemd-network/ipv4ll-packet.c \
-	src/libsystemd-network/ipv4ll-internal.h \
+	src/libsystemd-network/sd-ipv4acd.c \
+	src/libsystemd-network/arp-util.h \
+	src/libsystemd-network/arp-util.c \
 	src/libsystemd-network/sd-pppoe.c \
 	src/libsystemd-network/network-internal.c \
 	src/libsystemd-network/network-internal.h \
@@ -3273,13 +3276,29 @@ test_dhcp_server_LDADD = \
 
 test_ipv4ll_SOURCES = \
 	src/systemd/sd-ipv4ll.h \
-	src/libsystemd-network/ipv4ll-internal.h \
+	src/libsystemd-network/arp-util.h \
 	src/libsystemd-network/test-ipv4ll.c
 
 test_ipv4ll_LDADD = \
 	libsystemd-network.la \
 	libshared.la
 
+test_ipv4ll_manual_SOURCES = \
+	src/systemd/sd-ipv4ll.h \
+	src/libsystemd-network/test-ipv4ll-manual.c
+
+test_ipv4ll_manual_LDADD = \
+	libsystemd-network.la \
+	libshared.la
+
+test_acd_SOURCES = \
+	src/systemd/sd-ipv4acd.h \
+	src/libsystemd-network/test-acd.c
+
+test_acd_LDADD = \
+	libsystemd-network.la \
+	libshared.la
+
 test_pppoe_SOURCES = \
 	src/systemd/sd-pppoe.h \
 	src/libsystemd-network/test-pppoe.c
diff --git a/src/libsystemd-network/arp-util.c b/src/libsystemd-network/arp-util.c
new file mode 100644
index 0000000000..2f5b9b3731
--- /dev/null
+++ b/src/libsystemd-network/arp-util.c
@@ -0,0 +1,153 @@
+/***
+  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
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <linux/filter.h>
+#include <arpa/inet.h>
+
+#include "util.h"
+#include "arp-util.h"
+
+int arp_network_bind_raw_socket(int ifindex, be32_t address, const struct ether_addr *eth_mac) {
+        struct sock_filter filter[] = {
+                BPF_STMT(BPF_LD + BPF_W + BPF_LEN, 0),                                         /* A <- packet length */
+                BPF_JUMP(BPF_JMP + BPF_JGE + BPF_K, sizeof(struct ether_arp), 1, 0),           /* packet >= arp packet ? */
+                BPF_STMT(BPF_RET + BPF_K, 0),                                                  /* ignore */
+                BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(struct ether_arp, ea_hdr.ar_hrd)), /* A <- header */
+                BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ARPHRD_ETHER, 1, 0),                       /* header == ethernet ? */
+                BPF_STMT(BPF_RET + BPF_K, 0),                                                  /* ignore */
+                BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(struct ether_arp, ea_hdr.ar_pro)), /* A <- protocol */
+                BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ETHERTYPE_IP, 1, 0),                       /* protocol == IP ? */
+                BPF_STMT(BPF_RET + BPF_K, 0),                                                  /* ignore */
+                BPF_STMT(BPF_LD + BPF_B + BPF_ABS, offsetof(struct ether_arp, ea_hdr.ar_hln)), /* A <- hardware address length */
+                BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, sizeof(struct ether_addr), 1, 0),          /* length == sizeof(ether_addr)? */
+                BPF_STMT(BPF_RET + BPF_K, 0),                                                  /* ignore */
+                BPF_STMT(BPF_LD + BPF_B + BPF_ABS, offsetof(struct ether_arp, ea_hdr.ar_pln)), /* A <- protocol address length */
+                BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, sizeof(struct in_addr), 1, 0),             /* length == sizeof(in_addr) ? */
+                BPF_STMT(BPF_RET + BPF_K, 0),                                                  /* ignore */
+                BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(struct ether_arp, ea_hdr.ar_op)),  /* A <- operation */
+                BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ARPOP_REQUEST, 2, 0),                      /* protocol == request ? */
+                BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ARPOP_REPLY, 1, 0),                        /* protocol == reply ? */
+                BPF_STMT(BPF_RET + BPF_K, 0),                                                  /* ignore */
+                /* Sender Hardware Address must be different from our own */
+                BPF_STMT(BPF_LD + BPF_IMM, htobe32(*((uint32_t *) eth_mac))),                  /* A <- 4 bytes of client's MAC */
+                BPF_STMT(BPF_MISC + BPF_TAX, 0),                                               /* X <- A */
+                BPF_STMT(BPF_LD + BPF_W + BPF_ABS, offsetof(struct ether_arp, arp_sha)),       /* A <- 4 bytes of SHA */
+                BPF_STMT(BPF_ALU + BPF_XOR + BPF_X, 0),                                        /* A xor X */
+                BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0, 0, 6),                                  /* A == 0 ? */
+                BPF_STMT(BPF_LD + BPF_IMM, htobe16(*((uint16_t *) (((char *) eth_mac) + 4)))), /* A <- remainder of client's MAC */
+                BPF_STMT(BPF_MISC + BPF_TAX, 0),                                               /* X <- A */
+                BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(struct ether_arp, arp_sha) + 4),   /* A <- remainder of SHA */
+                BPF_STMT(BPF_ALU + BPF_XOR + BPF_X, 0),                                        /* A xor X */
+                BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0, 0, 1),                                  /* A == 0 ? */
+                BPF_STMT(BPF_RET + BPF_K, 0),                                                  /* ignore */
+                /* Sender Protocol Address or Target Protocol Address must be equal to the one we care about*/
+                BPF_STMT(BPF_LD + BPF_IMM, htobe32(address)),                                  /* A <- clients IP */
+                BPF_STMT(BPF_MISC + BPF_TAX, 0),                                               /* X <- A */
+                BPF_STMT(BPF_LD + BPF_W + BPF_ABS, offsetof(struct ether_arp, arp_spa)),       /* A <- SPA */
+                BPF_STMT(BPF_ALU + BPF_XOR + BPF_X, 0),                                        /* X xor A */
+                BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0, 0, 1),                                  /* A == 0 ? */
+                BPF_STMT(BPF_RET + BPF_K, 65535),                                              /* return all */
+                BPF_STMT(BPF_LD + BPF_IMM, htobe32(address)),                                  /* A <- clients IP */
+                BPF_STMT(BPF_MISC + BPF_TAX, 0),                                               /* X <- A */
+                BPF_STMT(BPF_LD + BPF_W + BPF_ABS, offsetof(struct ether_arp, arp_tpa)),       /* A <- TPA */
+                BPF_STMT(BPF_ALU + BPF_XOR + BPF_X, 0),                                        /* X xor A */
+                BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0, 0, 1),                                  /* A == 0 ? */
+                BPF_STMT(BPF_RET + BPF_K, 65535),                                              /* return all */
+                BPF_STMT(BPF_RET + BPF_K, 0),                                                  /* ignore */
+        };
+        struct sock_fprog fprog = {
+                .len = ELEMENTSOF(filter),
+                .filter = (struct sock_filter*) filter
+        };
+        union sockaddr_union link = {
+                .ll.sll_family = AF_PACKET,
+                .ll.sll_protocol = htons(ETH_P_ARP),
+                .ll.sll_ifindex = ifindex,
+                .ll.sll_halen = ETH_ALEN,
+                .ll.sll_addr = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff },
+        };
+        _cleanup_close_ int s = -1;
+        int r;
+
+        assert(ifindex > 0);
+
+        s = socket(PF_PACKET, SOCK_DGRAM | SOCK_CLOEXEC | SOCK_NONBLOCK, 0);
+        if (s < 0)
+                return -errno;
+
+        r = setsockopt(s, SOL_SOCKET, SO_ATTACH_FILTER, &fprog, sizeof(fprog));
+        if (r < 0)
+                return -errno;
+
+        r = bind(s, &link.sa, sizeof(link.ll));
+        if (r < 0)
+                return -errno;
+
+        r = s;
+        s = -1;
+
+        return r;
+}
+
+static int arp_send_packet(int fd, int ifindex,
+                           be32_t pa, const struct ether_addr *ha,
+                           bool announce) {
+        union sockaddr_union link = {
+                .ll.sll_family = AF_PACKET,
+                .ll.sll_protocol = htons(ETH_P_ARP),
+                .ll.sll_ifindex = ifindex,
+                .ll.sll_halen = ETH_ALEN,
+                .ll.sll_addr = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff },
+        };
+        struct ether_arp arp = {
+                .ea_hdr.ar_hrd = htons(ARPHRD_ETHER), /* HTYPE */
+                .ea_hdr.ar_pro = htons(ETHERTYPE_IP), /* PTYPE */
+                .ea_hdr.ar_hln = ETH_ALEN, /* HLEN */
+                .ea_hdr.ar_pln = sizeof(be32_t), /* PLEN */
+                .ea_hdr.ar_op = htons(ARPOP_REQUEST), /* REQUEST */
+        };
+        int r;
+
+        assert(fd >= 0);
+        assert(pa != 0);
+        assert(ha);
+
+        memcpy(&arp.arp_sha, ha, ETH_ALEN);
+        memcpy(&arp.arp_tpa, &pa, sizeof(pa));
+
+        if (announce)
+                memcpy(&arp.arp_spa, &pa, sizeof(pa));
+
+        r = sendto(fd, &arp, sizeof(struct ether_arp), 0, &link.sa, sizeof(link.ll));
+        if (r < 0)
+                return -errno;
+
+        return 0;
+}
+
+int arp_send_probe(int fd, int ifindex,
+                    be32_t pa, const struct ether_addr *ha) {
+        return arp_send_packet(fd, ifindex, pa, ha, false);
+}
+
+int arp_send_announcement(int fd, int ifindex,
+                          be32_t pa, const struct ether_addr *ha) {
+        return arp_send_packet(fd, ifindex, pa, ha, true);
+}
diff --git a/src/libsystemd-network/ipv4ll-internal.h b/src/libsystemd-network/arp-util.h
index ae0ce43985..44e5c893a7 100644
--- a/src/libsystemd-network/ipv4ll-internal.h
+++ b/src/libsystemd-network/arp-util.h
@@ -26,13 +26,9 @@
 #include "sparse-endian.h"
 #include "socket-util.h"
 
-int arp_network_bind_raw_socket(int index, union sockaddr_union *link);
-int arp_network_send_raw_socket(int fd, const union sockaddr_union *link,
-                                        const struct ether_arp *arp);
+int arp_network_bind_raw_socket(int index, be32_t address, const struct ether_addr *eth_mac);
 
-void arp_packet_init(struct ether_arp *arp);
-void arp_packet_probe(struct ether_arp *arp, be32_t pa, const struct ether_addr *ha);
-void arp_packet_announcement(struct ether_arp *arp, be32_t pa, const struct ether_addr *ha);
-int arp_packet_verify_headers(struct ether_arp *arp);
-
-#define log_ipv4ll(ll, fmt, ...) log_internal(LOG_DEBUG, 0, __FILE__, __LINE__, __func__, "IPv4LL: " fmt, ##__VA_ARGS__)
+int arp_send_probe(int fd, int ifindex,
+                   be32_t pa, const struct ether_addr *ha);
+int arp_send_announcement(int fd, int ifindex,
+                          be32_t pa, const struct ether_addr *ha);
diff --git a/src/libsystemd-network/ipv4ll-network.c b/src/libsystemd-network/ipv4ll-network.c
deleted file mode 100644
index 93ffed408f..0000000000
--- a/src/libsystemd-network/ipv4ll-network.c
+++ /dev/null
@@ -1,91 +0,0 @@
-/***
-  This file is part of systemd.
-
-  Copyright (C) 2014 Axis Communications AB. All rights reserved.
-
-  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
-  the Free Software Foundation; either version 2.1 of the License, or
-  (at your option) any later version.
-
-  systemd is distributed in the hope that it will be useful, but
-  WITHOUT ANY WARRANTY; without even the implied warranty of
-  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
-  Lesser General Public License for more details.
-
-  You should have received a copy of the GNU Lesser General Public License
-  along with systemd; If not, see <http://www.gnu.org/licenses/>.
-***/
-
-#include <linux/filter.h>
-
-#include "util.h"
-#include "ipv4ll-internal.h"
-
-int arp_network_send_raw_socket(int fd, const union sockaddr_union *link,
-                                        const struct ether_arp *arp) {
-        int r;
-
-        assert(arp);
-        assert(link);
-        assert(fd >= 0);
-
-        r = sendto(fd, arp, sizeof(struct ether_arp), 0, &link->sa, sizeof(link->ll));
-        if (r < 0)
-                return -errno;
-
-        return 0;
-}
-
-int arp_network_bind_raw_socket(int ifindex, union sockaddr_union *link) {
-
-        static const struct sock_filter filter[] = {
-                BPF_STMT(BPF_LD + BPF_W + BPF_LEN, 0),                                         /* A <- packet length */
-                BPF_JUMP(BPF_JMP + BPF_JGE + BPF_K, sizeof(struct ether_arp), 1, 0),           /* packet >= arp packet ? */
-                BPF_STMT(BPF_RET + BPF_K, 0),                                                  /* ignore */
-                BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(struct ether_arp, ea_hdr.ar_hrd)), /* A <- header */
-                BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ARPHRD_ETHER, 1, 0),                       /* header == ethernet ? */
-                BPF_STMT(BPF_RET + BPF_K, 0),                                                  /* ignore */
-                BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(struct ether_arp, ea_hdr.ar_pro)), /* A <- protocol */
-                BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ETHERTYPE_IP, 1, 0),                       /* protocol == IP ? */
-                BPF_STMT(BPF_RET + BPF_K, 0),                                                  /* ignore */
-                BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(struct ether_arp, ea_hdr.ar_op)),  /* A <- operation */
-                BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ARPOP_REQUEST, 0, 1),                      /* protocol == request ? */
-                BPF_STMT(BPF_RET + BPF_K, 65535),                                              /* return all */
-                BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ARPOP_REPLY, 0, 1),                        /* protocol == reply ? */
-                BPF_STMT(BPF_RET + BPF_K, 65535),                                              /* return all */
-                BPF_STMT(BPF_RET + BPF_K, 0),                                                  /* ignore */
-        };
-        struct sock_fprog fprog = {
-                .len = ELEMENTSOF(filter),
-                .filter = (struct sock_filter*) filter
-        };
-        _cleanup_close_ int s = -1;
-        int r;
-
-        assert(ifindex > 0);
-        assert(link);
-
-        s = socket(PF_PACKET, SOCK_DGRAM | SOCK_CLOEXEC | SOCK_NONBLOCK, 0);
-        if (s < 0)
-                return -errno;
-
-        r = setsockopt(s, SOL_SOCKET, SO_ATTACH_FILTER, &fprog, sizeof(fprog));
-        if (r < 0)
-                return -errno;
-
-        link->ll.sll_family = AF_PACKET;
-        link->ll.sll_protocol = htons(ETH_P_ARP);
-        link->ll.sll_ifindex = ifindex;
-        link->ll.sll_halen = ETH_ALEN;
-        memset(link->ll.sll_addr, 0xff, ETH_ALEN);
-
-        r = bind(s, &link->sa, sizeof(link->ll));
-        if (r < 0)
-                return -errno;
-
-        r = s;
-        s = -1;
-
-        return r;
-}
diff --git a/src/libsystemd-network/ipv4ll-packet.c b/src/libsystemd-network/ipv4ll-packet.c
deleted file mode 100644
index 2b6c73ab4b..0000000000
--- a/src/libsystemd-network/ipv4ll-packet.c
+++ /dev/null
@@ -1,71 +0,0 @@
-/***
-  This file is part of systemd.
-
-  Copyright (C) 2014 Axis Communications AB. All rights reserved.
-
-  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
-  the Free Software Foundation; either version 2.1 of the License, or
-  (at your option) any later version.
-
-  systemd is distributed in the hope that it will be useful, but
-  WITHOUT ANY WARRANTY; without even the implied warranty of
-  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
-  Lesser General Public License for more details.
-
-  You should have received a copy of the GNU Lesser General Public License
-  along with systemd; If not, see <http://www.gnu.org/licenses/>.
-***/
-#include <arpa/inet.h>
-
-#include "util.h"
-#include "ipv4ll-internal.h"
-
-void arp_packet_init(struct ether_arp *arp) {
-        assert(arp);
-
-        memzero(arp, sizeof(struct ether_arp));
-        /* Header */
-        arp->ea_hdr.ar_hrd = htons(ARPHRD_ETHER); /* HTYPE */
-        arp->ea_hdr.ar_pro = htons(ETHERTYPE_IP); /* PTYPE */
-        arp->ea_hdr.ar_hln = ETH_ALEN; /* HLEN */
-        arp->ea_hdr.ar_pln = sizeof arp->arp_spa; /* PLEN */
-        arp->ea_hdr.ar_op = htons(ARPOP_REQUEST); /* REQUEST */
-}
-
-void arp_packet_probe(struct ether_arp *arp, be32_t pa, const struct ether_addr *ha) {
-        assert(ha);
-
-        arp_packet_init(arp);
-        memcpy(arp->arp_sha, ha, ETH_ALEN);
-        memcpy(arp->arp_tpa, &pa, sizeof(pa));
-}
-
-void arp_packet_announcement(struct ether_arp *arp, be32_t pa, const struct ether_addr *ha) {
-        assert(ha);
-
-        arp_packet_init(arp);
-        memcpy(arp->arp_sha, ha, ETH_ALEN);
-        memcpy(arp->arp_tpa, &pa, sizeof(pa));
-        memcpy(arp->arp_spa, &pa, sizeof(pa));
-}
-
-int arp_packet_verify_headers(struct ether_arp *arp) {
-        assert(arp);
-
-        if (arp->ea_hdr.ar_hrd != htons(ARPHRD_ETHER)) {
-                log_ipv4ll(NULL, "ignoring packet: header is not ARPHRD_ETHER");
-                return -EINVAL;
-        }
-        if (arp->ea_hdr.ar_pro != htons(ETHERTYPE_IP)) {
-                log_ipv4ll(NULL, "ignoring packet: protocol is not ETHERTYPE_IP");
-                return -EINVAL;
-        }
-        if (arp->ea_hdr.ar_op != htons(ARPOP_REQUEST) &&
-            arp->ea_hdr.ar_op != htons(ARPOP_REPLY)) {
-                log_ipv4ll(NULL, "ignoring packet: operation is not ARPOP_REQUEST or ARPOP_REPLY");
-                return -EINVAL;
-        }
-
-        return 0;
-}
diff --git a/src/libsystemd-network/sd-ipv4acd.c b/src/libsystemd-network/sd-ipv4acd.c
new file mode 100644
index 0000000000..ee5d13c030
--- /dev/null
+++ b/src/libsystemd-network/sd-ipv4acd.c
@@ -0,0 +1,529 @@
+/***
+  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
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <arpa/inet.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "event-util.h"
+#include "in-addr-util.h"
+#include "list.h"
+#include "refcnt.h"
+#include "random-util.h"
+#include "siphash24.h"
+#include "util.h"
+
+#include "arp-util.h"
+#include "sd-ipv4acd.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 IPV4ACD_NETWORK 0xA9FE0000L
+#define IPV4ACD_NETMASK 0xFFFF0000L
+
+#define log_ipv4acd_full(ll, level, error, fmt, ...) log_internal(level, error, __FILE__, __LINE__, __func__, "ACD: " fmt, ##__VA_ARGS__)
+
+#define log_ipv4acd_debug(ll, ...)   log_ipv4acd_full(ll, LOG_DEBUG, 0, ##__VA_ARGS__)
+#define log_ipv4acd_info(ll, ...)    log_ipv4acd_full(ll, LOG_INFO, 0, ##__VA_ARGS__)
+#define log_ipv4acd_notice(ll, ...)  log_ipv4acd_full(ll, LOG_NOTICE, 0, ##__VA_ARGS__)
+#define log_ipv4acd_warning(ll, ...) log_ipv4acd_full(ll, LOG_WARNING, 0, ##__VA_ARGS__)
+#define log_ipv4acd_error(ll, ...)   log_ipv4acd_full(ll, LOG_ERR, 0, ##__VA_ARGS__)
+
+#define log_ipv4acd_debug_errno(ll, error, ...)   log_ipv4acd_full(ll, LOG_DEBUG, error, ##__VA_ARGS__)
+#define log_ipv4acd_info_errno(ll, error, ...)    log_ipv4acd_full(ll, LOG_INFO, error, ##__VA_ARGS__)
+#define log_ipv4acd_notice_errno(ll, error, ...)  log_ipv4acd_full(ll, LOG_NOTICE, error, ##__VA_ARGS__)
+#define log_ipv4acd_warning_errno(ll, error, ...) log_ipv4acd_full(ll, LOG_WARNING, error, ##__VA_ARGS__)
+#define log_ipv4acd_error_errno(ll, error, ...)   log_ipv4acd_full(ll, LOG_ERR, error, ##__VA_ARGS__)
+
+typedef enum IPv4ACDState {
+        IPV4ACD_STATE_INIT,
+        IPV4ACD_STATE_WAITING_PROBE,
+        IPV4ACD_STATE_PROBING,
+        IPV4ACD_STATE_WAITING_ANNOUNCE,
+        IPV4ACD_STATE_ANNOUNCING,
+        IPV4ACD_STATE_RUNNING,
+        _IPV4ACD_STATE_MAX,
+        _IPV4ACD_STATE_INVALID = -1
+} IPv4ACDState;
+
+struct sd_ipv4acd {
+        RefCount n_ref;
+
+        IPv4ACDState state;
+        int index;
+        int fd;
+        int iteration;
+        int conflict;
+        sd_event_source *receive_message;
+        sd_event_source *timer;
+        usec_t defend_window;
+        be32_t address;
+        /* External */
+        struct ether_addr mac_addr;
+        sd_event *event;
+        int event_priority;
+        sd_ipv4acd_cb_t cb;
+        void* userdata;
+};
+
+sd_ipv4acd *sd_ipv4acd_ref(sd_ipv4acd *ll) {
+        if (ll)
+                assert_se(REFCNT_INC(ll->n_ref) >= 2);
+
+        return ll;
+}
+
+sd_ipv4acd *sd_ipv4acd_unref(sd_ipv4acd *ll) {
+        if (!ll || REFCNT_DEC(ll->n_ref) > 0)
+                return NULL;
+
+        ll->receive_message = sd_event_source_unref(ll->receive_message);
+        ll->fd = safe_close(ll->fd);
+
+        ll->timer = sd_event_source_unref(ll->timer);
+
+        sd_ipv4acd_detach_event(ll);
+
+        free(ll);
+
+        return NULL;
+}
+
+DEFINE_TRIVIAL_CLEANUP_FUNC(sd_ipv4acd*, sd_ipv4acd_unref);
+#define _cleanup_ipv4acd_unref_ _cleanup_(sd_ipv4acd_unrefp)
+
+int sd_ipv4acd_new(sd_ipv4acd **ret) {
+        _cleanup_ipv4acd_unref_ sd_ipv4acd *ll = NULL;
+
+        assert_return(ret, -EINVAL);
+
+        ll = new0(sd_ipv4acd, 1);
+        if (!ll)
+                return -ENOMEM;
+
+        ll->n_ref = REFCNT_INIT;
+        ll->state = IPV4ACD_STATE_INIT;
+        ll->index = -1;
+        ll->fd = -1;
+
+        *ret = ll;
+        ll = NULL;
+
+        return 0;
+}
+
+static void ipv4acd_set_state(sd_ipv4acd *ll, IPv4ACDState st, bool reset_counter) {
+
+        assert(ll);
+        assert(st < _IPV4ACD_STATE_MAX);
+
+        if (st == ll->state && !reset_counter)
+                ll->iteration++;
+        else {
+                ll->state = st;
+                ll->iteration = 0;
+        }
+}
+
+static void ipv4acd_client_notify(sd_ipv4acd *ll, int event) {
+        assert(ll);
+
+        if (ll->cb)
+                ll->cb(ll, event, ll->userdata);
+}
+
+static void ipv4acd_stop(sd_ipv4acd *ll) {
+        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_ipv4acd_debug(ll, "STOPPED");
+
+        ipv4acd_set_state (ll, IPV4ACD_STATE_INIT, true);
+}
+
+int sd_ipv4acd_stop(sd_ipv4acd *ll) {
+        assert_return(ll, -EINVAL);
+
+        ipv4acd_stop(ll);
+
+        ipv4acd_client_notify(ll, IPV4ACD_EVENT_STOP);
+
+        return 0;
+}
+
+static int ipv4acd_on_timeout(sd_event_source *s, uint64_t usec, void *userdata);
+
+static int ipv4acd_set_next_wakeup(sd_ipv4acd *ll, int sec, int random_sec) {
+        _cleanup_event_source_unref_ sd_event_source *timer = NULL;
+        usec_t next_timeout;
+        usec_t time_now;
+        int r;
+
+        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);
+
+        r = sd_event_add_time(ll->event, &timer, clock_boottime_or_monotonic(),
+                              time_now + next_timeout, 0, ipv4acd_on_timeout, ll);
+        if (r < 0)
+                return r;
+
+        r = sd_event_source_set_priority(timer, ll->event_priority);
+        if (r < 0)
+                return r;
+
+        r = sd_event_source_set_description(timer, "ipv4acd-timer");
+        if (r < 0)
+                return r;
+
+        ll->timer = sd_event_source_unref(ll->timer);
+        ll->timer = timer;
+        timer = NULL;
+
+        return 0;
+}
+
+static bool ipv4acd_arp_conflict(sd_ipv4acd *ll, struct ether_arp *arp) {
+        assert(ll);
+        assert(arp);
+
+        /* see the BPF */
+        if (memcmp(arp->arp_spa, &ll->address, sizeof(ll->address)) == 0)
+                return true;
+
+        /* the TPA matched instead of the SPA, this is not a conflict */
+        return false;
+}
+
+static int ipv4acd_on_timeout(sd_event_source *s, uint64_t usec, void *userdata) {
+        sd_ipv4acd *ll = userdata;
+        int r = 0;
+
+        assert(ll);
+
+        switch (ll->state) {
+        case IPV4ACD_STATE_INIT:
+
+                ipv4acd_set_state(ll, IPV4ACD_STATE_WAITING_PROBE, true);
+
+                if (ll->conflict >= MAX_CONFLICTS) {
+                        log_ipv4acd_notice(ll, "Max conflicts reached, delaying by %us", RATE_LIMIT_INTERVAL);
+                        r = ipv4acd_set_next_wakeup(ll, RATE_LIMIT_INTERVAL, PROBE_WAIT);
+                        if (r < 0)
+                                goto out;
+
+                        ll->conflict = 0;
+                } else {
+                        r = ipv4acd_set_next_wakeup(ll, 0, PROBE_WAIT);
+                        if (r < 0)
+                                goto out;
+                }
+
+                break;
+        case IPV4ACD_STATE_WAITING_PROBE:
+        case IPV4ACD_STATE_PROBING:
+                /* Send a probe */
+                r = arp_send_probe(ll->fd, ll->index, ll->address, &ll->mac_addr);
+                if (r < 0) {
+                        log_ipv4acd_error_errno(ll, r, "Failed to send ARP probe: %m");
+                        goto out;
+                } else {
+                        _cleanup_free_ char *address = NULL;
+                        union in_addr_union addr = { .in.s_addr = ll->address };
+
+                        r = in_addr_to_string(AF_INET, &addr, &address);
+                        if (r >= 0)
+                                log_ipv4acd_debug(ll, "Probing %s", address);
+                }
+
+                if (ll->iteration < PROBE_NUM - 2) {
+                        ipv4acd_set_state(ll, IPV4ACD_STATE_PROBING, false);
+
+                        r = ipv4acd_set_next_wakeup(ll, PROBE_MIN, (PROBE_MAX-PROBE_MIN));
+                        if (r < 0)
+                                goto out;
+                } else {
+                        ipv4acd_set_state(ll, IPV4ACD_STATE_WAITING_ANNOUNCE, true);
+
+                        r = ipv4acd_set_next_wakeup(ll, ANNOUNCE_WAIT, 0);
+                        if (r < 0)
+                                goto out;
+                }
+
+                break;
+
+        case IPV4ACD_STATE_ANNOUNCING:
+                if (ll->iteration >= ANNOUNCE_NUM - 1) {
+                        ipv4acd_set_state(ll, IPV4ACD_STATE_RUNNING, false);
+
+                        break;
+                }
+        case IPV4ACD_STATE_WAITING_ANNOUNCE:
+                /* Send announcement packet */
+                r = arp_send_announcement(ll->fd, ll->index, ll->address, &ll->mac_addr);
+                if (r < 0) {
+                        log_ipv4acd_error_errno(ll, r, "Failed to send ARP announcement: %m");
+                        goto out;
+                } else
+                        log_ipv4acd_debug(ll, "ANNOUNCE");
+
+                ipv4acd_set_state(ll, IPV4ACD_STATE_ANNOUNCING, false);
+
+                r = ipv4acd_set_next_wakeup(ll, ANNOUNCE_INTERVAL, 0);
+                if (r < 0)
+                        goto out;
+
+                if (ll->iteration == 0) {
+                        ll->conflict = 0;
+                        ipv4acd_client_notify(ll, IPV4ACD_EVENT_BIND);
+                }
+
+                break;
+        default:
+                assert_not_reached("Invalid state.");
+        }
+
+out:
+        if (r < 0)
+                sd_ipv4acd_stop(ll);
+
+        return 1;
+}
+
+static void ipv4acd_on_conflict(sd_ipv4acd *ll) {
+        _cleanup_free_ char *address = NULL;
+        union in_addr_union addr = { .in.s_addr = ll->address };
+        int r;
+
+        assert(ll);
+
+        ll->conflict++;
+
+        r = in_addr_to_string(AF_INET, &addr, &address);
+        if (r >= 0)
+                log_ipv4acd_debug(ll, "Conflict on %s (%u)", address, ll->conflict);
+
+        ipv4acd_stop(ll);
+
+        ipv4acd_client_notify(ll, IPV4ACD_EVENT_CONFLICT);
+}
+
+static int ipv4acd_on_packet(sd_event_source *s, int fd,
+                            uint32_t revents, void *userdata) {
+        sd_ipv4acd *ll = userdata;
+        struct ether_arp packet;
+        int r;
+
+        assert(ll);
+        assert(fd >= 0);
+
+        r = read(fd, &packet, sizeof(struct ether_arp));
+        if (r < (int) sizeof(struct ether_arp))
+                goto out;
+
+        switch (ll->state) {
+        case IPV4ACD_STATE_ANNOUNCING:
+        case IPV4ACD_STATE_RUNNING:
+                if (ipv4acd_arp_conflict(ll, &packet)) {
+                        usec_t ts;
+
+                        assert_se(sd_event_now(ll->event, clock_boottime_or_monotonic(), &ts) >= 0);
+
+                        /* Defend address */
+                        if (ts > ll->defend_window) {
+                                ll->defend_window = ts + DEFEND_INTERVAL * USEC_PER_SEC;
+                                r = arp_send_announcement(ll->fd, ll->index, ll->address, &ll->mac_addr);
+                                if (r < 0) {
+                                        log_ipv4acd_error_errno(ll, r, "Failed to send ARP announcement: %m");
+                                        goto out;
+                                } else
+                                        log_ipv4acd_debug(ll, "DEFEND");
+
+                        } else
+                                ipv4acd_on_conflict(ll);
+                }
+
+                break;
+        case IPV4ACD_STATE_WAITING_PROBE:
+        case IPV4ACD_STATE_PROBING:
+        case IPV4ACD_STATE_WAITING_ANNOUNCE:
+                /* BPF ensures this packet indicates a conflict */
+                ipv4acd_on_conflict(ll);
+
+                break;
+        default:
+                assert_not_reached("Invalid state.");
+        }
+
+out:
+        if (r < 0)
+                sd_ipv4acd_stop(ll);
+
+        return 1;
+}
+
+int sd_ipv4acd_set_index(sd_ipv4acd *ll, int interface_index) {
+        assert_return(ll, -EINVAL);
+        assert_return(interface_index > 0, -EINVAL);
+        assert_return(ll->state == IPV4ACD_STATE_INIT, -EBUSY);
+
+        ll->index = interface_index;
+
+        return 0;
+}
+
+int sd_ipv4acd_set_mac(sd_ipv4acd *ll, const struct ether_addr *addr) {
+        assert_return(ll, -EINVAL);
+        assert_return(addr, -EINVAL);
+        assert_return(ll->state == IPV4ACD_STATE_INIT, -EBUSY);
+
+        memcpy(&ll->mac_addr, addr, ETH_ALEN);
+
+        return 0;
+}
+
+int sd_ipv4acd_detach_event(sd_ipv4acd *ll) {
+        assert_return(ll, -EINVAL);
+
+        ll->event = sd_event_unref(ll->event);
+
+        return 0;
+}
+
+int sd_ipv4acd_attach_event(sd_ipv4acd *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)
+                        return r;
+        }
+
+        ll->event_priority = priority;
+
+        return 0;
+}
+
+int sd_ipv4acd_set_callback(sd_ipv4acd *ll, sd_ipv4acd_cb_t cb, void *userdata) {
+        assert_return(ll, -EINVAL);
+
+        ll->cb = cb;
+        ll->userdata = userdata;
+
+        return 0;
+}
+
+int sd_ipv4acd_set_address(sd_ipv4acd *ll, const struct in_addr *address){
+        assert_return(ll, -EINVAL);
+        assert_return(address, -EINVAL);
+        assert_return(ll->state == IPV4ACD_STATE_INIT, -EBUSY);
+
+        ll->address = address->s_addr;
+
+        return 0;
+}
+
+bool sd_ipv4acd_is_running(sd_ipv4acd *ll) {
+        assert_return(ll, false);
+
+        return ll->state != IPV4ACD_STATE_INIT;
+}
+
+static bool ether_addr_is_nul(const struct ether_addr *addr) {
+        const struct ether_addr nul_addr = {};
+
+        assert(addr);
+
+        return memcmp(addr, &nul_addr, sizeof(struct ether_addr)) == 0;
+}
+
+#define HASH_KEY SD_ID128_MAKE(df,04,22,98,3f,ad,14,52,f9,87,2e,d1,9c,70,e2,f2)
+
+int sd_ipv4acd_start(sd_ipv4acd *ll) {
+        int r;
+
+        assert_return(ll, -EINVAL);
+        assert_return(ll->event, -EINVAL);
+        assert_return(ll->index > 0, -EINVAL);
+        assert_return(ll->address != 0, -EINVAL);
+        assert_return(!ether_addr_is_nul(&ll->mac_addr), -EINVAL);
+        assert_return(ll->state == IPV4ACD_STATE_INIT, -EBUSY);
+
+        ll->defend_window = 0;
+
+        r = arp_network_bind_raw_socket(ll->index, ll->address, &ll->mac_addr);
+        if (r < 0)
+                goto out;
+
+        ll->fd = safe_close(ll->fd);
+        ll->fd = r;
+
+        r = sd_event_add_io(ll->event, &ll->receive_message, ll->fd,
+                            EPOLLIN, ipv4acd_on_packet, ll);
+        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, "ipv4acd-receive-message");
+        if (r < 0)
+                goto out;
+
+        r = ipv4acd_set_next_wakeup(ll, 0, 0);
+        if (r < 0)
+                goto out;
+out:
+        if (r < 0) {
+                ipv4acd_stop(ll);
+                return r;
+        }
+
+        return 0;
+}
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);
 }
diff --git a/src/libsystemd-network/test-acd.c b/src/libsystemd-network/test-acd.c
new file mode 100644
index 0000000000..f1f14ee119
--- /dev/null
+++ b/src/libsystemd-network/test-acd.c
@@ -0,0 +1,117 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright (C) 2014 Tom Gundersen <teg@jklm.no>
+
+  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
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <stdlib.h>
+#include <errno.h>
+#include <unistd.h>
+
+#include <linux/veth.h>
+#include <net/if.h>
+
+#include "sd-event.h"
+#include "sd-netlink.h"
+#include "sd-ipv4acd.h"
+
+#include "util.h"
+#include "event-util.h"
+#include "netlink-util.h"
+#include "in-addr-util.h"
+
+static void acd_handler(sd_ipv4acd *acd, int event, void *userdata) {
+        assert_se(acd);
+
+        switch (event) {
+        case IPV4ACD_EVENT_BIND:
+                log_info("bound");
+                break;
+        case IPV4ACD_EVENT_CONFLICT:
+                log_info("conflict");
+                break;
+        case IPV4ACD_EVENT_STOP:
+                log_error("the client was stopped");
+                break;
+        default:
+                assert_not_reached("invalid ACD event");
+        }
+}
+
+static int client_run(int ifindex, const struct in_addr *pa, const struct ether_addr *ha, sd_event *e) {
+        sd_ipv4acd *acd;
+
+        assert_se(sd_ipv4acd_new(&acd) >= 0);
+        assert_se(sd_ipv4acd_attach_event(acd, e, 0) >= 0);
+
+        assert_se(sd_ipv4acd_set_index(acd, ifindex) >= 0);
+        assert_se(sd_ipv4acd_set_mac(acd, ha) >= 0);
+        assert_se(sd_ipv4acd_set_address(acd, pa) >= 0);
+        assert_se(sd_ipv4acd_set_callback(acd, acd_handler, NULL) >= 0);
+
+        log_info("starting IPv4ACD client");
+
+        assert_se(sd_ipv4acd_start(acd) >= 0);
+
+        assert_se(sd_event_loop(e) >= 0);
+
+        assert_se(!sd_ipv4acd_unref(acd));
+
+        return EXIT_SUCCESS;
+}
+
+static int test_acd(const char *ifname, const char *address) {
+        _cleanup_event_unref_ sd_event *e = NULL;
+        _cleanup_netlink_unref_ sd_netlink *rtnl = NULL;
+        _cleanup_netlink_message_unref_ sd_netlink_message *m = NULL, *reply = NULL;
+        union in_addr_union pa;
+        struct ether_addr ha;
+        int ifindex;
+
+        assert_se(in_addr_from_string(AF_INET, address, &pa) >= 0);
+
+        assert_se(sd_event_new(&e) >= 0);
+
+        assert_se(sd_netlink_open(&rtnl) >= 0);
+        assert_se(sd_netlink_attach_event(rtnl, e, 0) >= 0);
+
+        assert_se(sd_rtnl_message_new_link(rtnl, &m, RTM_GETLINK, 0) >= 0);
+        assert_se(sd_netlink_message_append_string(m, IFLA_IFNAME, ifname) >= 0);
+        assert_se(sd_netlink_call(rtnl, m, 0, &reply) >= 0);
+
+        assert_se(sd_rtnl_message_link_get_ifindex(reply, &ifindex) >= 0);
+        assert_se(sd_netlink_message_read_ether_addr(reply, IFLA_ADDRESS, &ha) >= 0);
+
+        client_run(ifindex, &pa.in, &ha, e);
+
+        return EXIT_SUCCESS;
+}
+
+int main(int argc, char *argv[]) {
+        log_set_max_level(LOG_DEBUG);
+        log_parse_environment();
+        log_open();
+
+        if (argc == 3)
+                return test_acd(argv[1], argv[2]);
+        else {
+                log_error("This program takes two arguments.\n"
+                          "\t %s <ifname> <IPv4 address>", program_invocation_short_name);
+                return EXIT_FAILURE;
+        }
+}
diff --git a/src/libsystemd-network/test-ipv4ll-manual.c b/src/libsystemd-network/test-ipv4ll-manual.c
new file mode 100644
index 0000000000..ad664cba51
--- /dev/null
+++ b/src/libsystemd-network/test-ipv4ll-manual.c
@@ -0,0 +1,129 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright (C) 2014 Tom Gundersen <teg@jklm.no>
+
+  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
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <stdlib.h>
+#include <errno.h>
+#include <unistd.h>
+
+#include <linux/veth.h>
+#include <net/if.h>
+
+#include "sd-event.h"
+#include "sd-netlink.h"
+#include "sd-ipv4ll.h"
+
+#include "util.h"
+#include "event-util.h"
+#include "netlink-util.h"
+#include "in-addr-util.h"
+
+static void ll_handler(sd_ipv4ll *ll, int event, void *userdata) {
+        _cleanup_free_ char *address = NULL;
+        struct in_addr addr = {};
+
+        assert_se(ll);
+
+        if (sd_ipv4ll_get_address(ll, &addr) >= 0)
+                assert_se(in_addr_to_string(AF_INET, (const union in_addr_union*) &addr, &address) >= 0);
+
+        switch (event) {
+        case IPV4LL_EVENT_BIND:
+                log_info("bound %s", strna(address));
+                break;
+        case IPV4LL_EVENT_CONFLICT:
+                log_info("conflict on %s", strna(address));
+                break;
+        case IPV4LL_EVENT_STOP:
+                log_error("the client was stopped with address %s", strna(address));
+                break;
+        default:
+                assert_not_reached("invalid LL event");
+        }
+}
+
+static int client_run(int ifindex, const char *seed_str, const struct ether_addr *ha, sd_event *e) {
+        sd_ipv4ll *ll;
+
+        assert_se(sd_ipv4ll_new(&ll) >= 0);
+        assert_se(sd_ipv4ll_attach_event(ll, e, 0) >= 0);
+
+        assert_se(sd_ipv4ll_set_index(ll, ifindex) >= 0);
+        assert_se(sd_ipv4ll_set_mac(ll, ha) >= 0);
+        assert_se(sd_ipv4ll_set_callback(ll, ll_handler, NULL) >= 0);
+
+        if (seed_str) {
+                unsigned seed;
+
+                assert_se(safe_atou(seed_str, &seed) >= 0);
+
+                assert_se(sd_ipv4ll_set_address_seed(ll, seed) >= 0);
+        }
+
+        log_info("starting IPv4LL client");
+
+        assert_se(sd_ipv4ll_start(ll) >= 0);
+
+        assert_se(sd_event_loop(e) >= 0);
+
+        assert_se(!sd_ipv4ll_unref(ll));
+
+        return EXIT_SUCCESS;
+}
+
+static int test_ll(const char *ifname, const char *seed) {
+        _cleanup_event_unref_ sd_event *e = NULL;
+        _cleanup_netlink_unref_ sd_netlink *rtnl = NULL;
+        _cleanup_netlink_message_unref_ sd_netlink_message *m = NULL, *reply = NULL;
+        struct ether_addr ha;
+        int ifindex;
+
+        assert_se(sd_event_new(&e) >= 0);
+
+        assert_se(sd_netlink_open(&rtnl) >= 0);
+        assert_se(sd_netlink_attach_event(rtnl, e, 0) >= 0);
+
+        assert_se(sd_rtnl_message_new_link(rtnl, &m, RTM_GETLINK, 0) >= 0);
+        assert_se(sd_netlink_message_append_string(m, IFLA_IFNAME, ifname) >= 0);
+        assert_se(sd_netlink_call(rtnl, m, 0, &reply) >= 0);
+
+        assert_se(sd_rtnl_message_link_get_ifindex(reply, &ifindex) >= 0);
+        assert_se(sd_netlink_message_read_ether_addr(reply, IFLA_ADDRESS, &ha) >= 0);
+
+        client_run(ifindex, seed, &ha, e);
+
+        return EXIT_SUCCESS;
+}
+
+int main(int argc, char *argv[]) {
+        log_set_max_level(LOG_DEBUG);
+        log_parse_environment();
+        log_open();
+
+        if (argc == 2)
+                return test_ll(argv[1], NULL);
+        else if (argc == 3)
+                return test_ll(argv[1], argv[2]);
+        else {
+                log_error("This program takes one or two arguments.\n"
+                          "\t %s <ifname> [<seed>]", program_invocation_short_name);
+                return EXIT_FAILURE;
+        }
+}
diff --git a/src/libsystemd-network/test-ipv4ll.c b/src/libsystemd-network/test-ipv4ll.c
index d60ee98b25..f0e26bda07 100644
--- a/src/libsystemd-network/test-ipv4ll.c
+++ b/src/libsystemd-network/test-ipv4ll.c
@@ -31,7 +31,7 @@
 #include "event-util.h"
 
 #include "sd-ipv4ll.h"
-#include "ipv4ll-internal.h"
+#include "arp-util.h"
 
 static bool verbose = false;
 static bool extended = false;
@@ -56,10 +56,10 @@ static void basic_request_handler(sd_ipv4ll *ll, int event, void *userdata) {
         }
 }
 
-int arp_network_send_raw_socket(int fd, const union sockaddr_union *link,
-                                        const struct ether_arp *arp) {
+static int arp_network_send_raw_socket(int fd, int ifindex,
+                                       const struct ether_arp *arp) {
         assert_se(arp);
-        assert_se(link);
+        assert_se(ifindex > 0);
         assert_se(fd >= 0);
 
         if (send(fd, arp, sizeof(struct ether_arp), 0) < 0)
@@ -68,51 +68,35 @@ int arp_network_send_raw_socket(int fd, const union sockaddr_union *link,
         return 0;
 }
 
-int arp_network_bind_raw_socket(int index, union sockaddr_union *link) {
-        if (socketpair(AF_UNIX, SOCK_DGRAM | SOCK_NONBLOCK, 0, test_fd) < 0)
-                return -errno;
+int arp_send_probe(int fd, int ifindex,
+                    be32_t pa, const struct ether_addr *ha) {
+        struct ether_arp ea = {};
 
-        return test_fd[0];
-}
+        assert(fd >= 0);
+        assert(ifindex > 0);
+        assert(pa != 0);
+        assert(ha);
 
-static void test_arp_header(struct ether_arp *arp) {
-        assert_se(arp);
-        assert_se(arp->ea_hdr.ar_hrd == htons(ARPHRD_ETHER)); /* HTYPE */
-        assert_se(arp->ea_hdr.ar_pro == htons(ETHERTYPE_IP)); /* PTYPE */
-        assert_se(arp->ea_hdr.ar_hln == ETH_ALEN); /* HLEN */
-        assert_se(arp->ea_hdr.ar_pln == sizeof arp->arp_spa); /* PLEN */
-        assert_se(arp->ea_hdr.ar_op == htons(ARPOP_REQUEST)); /* REQUEST */
+        return arp_network_send_raw_socket(fd, ifindex, &ea);
 }
 
-static void test_arp_probe(void) {
-        struct ether_arp arp;
-        struct ether_addr mac_addr = {
-                .ether_addr_octet = {'A', 'B', 'C', '1', '2', '3'}};
-        be32_t pa = 0x3030;
+int arp_send_announcement(int fd, int ifindex,
+                          be32_t pa, const struct ether_addr *ha) {
+        struct ether_arp ea = {};
 
-        if (verbose)
-                printf("* %s\n", __FUNCTION__);
+        assert(fd >= 0);
+        assert(ifindex > 0);
+        assert(pa != 0);
+        assert(ha);
 
-        arp_packet_probe(&arp, pa, &mac_addr);
-        test_arp_header(&arp);
-        assert_se(memcmp(arp.arp_sha, &mac_addr, ETH_ALEN) == 0);
-        assert_se(memcmp(arp.arp_tpa, &pa, sizeof(pa)) == 0);
+        return arp_network_send_raw_socket(fd, ifindex, &ea);
 }
 
-static void test_arp_announce(void) {
-        struct ether_arp arp;
-        struct ether_addr mac_addr = {
-                .ether_addr_octet = {'A', 'B', 'C', '1', '2', '3'}};
-        be32_t pa = 0x3131;
-
-        if (verbose)
-                printf("* %s\n", __FUNCTION__);
+int arp_network_bind_raw_socket(int index, be32_t address, const struct ether_addr *eth_mac) {
+        if (socketpair(AF_UNIX, SOCK_DGRAM | SOCK_NONBLOCK, 0, test_fd) < 0)
+                return -errno;
 
-        arp_packet_announcement(&arp, pa, &mac_addr);
-        test_arp_header(&arp);
-        assert_se(memcmp(arp.arp_sha, &mac_addr, ETH_ALEN) == 0);
-        assert_se(memcmp(arp.arp_tpa, &pa, sizeof(pa)) == 0);
-        assert_se(memcmp(arp.arp_spa, &pa, sizeof(pa)) == 0);
+        return test_fd[0];
 }
 
 static void test_public_api_setters(sd_event *e) {
@@ -134,9 +118,8 @@ static void test_public_api_setters(sd_event *e) {
         assert_se(sd_ipv4ll_set_callback(NULL, NULL, NULL) == -EINVAL);
         assert_se(sd_ipv4ll_set_callback(ll, NULL, NULL) == 0);
 
-        assert_se(sd_ipv4ll_set_address_seed(NULL, NULL) == -EINVAL);
-        assert_se(sd_ipv4ll_set_address_seed(ll, NULL) == -EINVAL);
-        assert_se(sd_ipv4ll_set_address_seed(ll, seed) == 0);
+        assert_se(sd_ipv4ll_set_address_seed(NULL, *(unsigned *) seed) == -EINVAL);
+        assert_se(sd_ipv4ll_set_address_seed(ll, *(unsigned *) seed) == 0);
 
         assert_se(sd_ipv4ll_set_mac(NULL, NULL) == -EINVAL);
         assert_se(sd_ipv4ll_set_mac(ll, NULL) == -EINVAL);
@@ -149,7 +132,7 @@ static void test_public_api_setters(sd_event *e) {
         assert_se(sd_ipv4ll_set_index(ll, 99) == 0);
 
         assert_se(sd_ipv4ll_ref(ll) == ll);
-        assert_se(sd_ipv4ll_unref(ll) == ll);
+        assert_se(sd_ipv4ll_unref(ll) == NULL);
 
         /* Cleanup */
         assert_se(sd_ipv4ll_unref(ll) == NULL);
@@ -184,21 +167,20 @@ static void test_basic_request(sd_event *e) {
         sd_event_run(e, (uint64_t) -1);
         assert_se(sd_ipv4ll_start(ll) == -EBUSY);
 
+        assert_se(sd_ipv4ll_is_running(ll));
+
         /* PROBE */
         sd_event_run(e, (uint64_t) -1);
         assert_se(read(test_fd[1], &arp, sizeof(struct ether_arp)) == sizeof(struct ether_arp));
-        test_arp_header(&arp);
 
         if (extended) {
                 /* PROBE */
                 sd_event_run(e, (uint64_t) -1);
                 assert_se(read(test_fd[1], &arp, sizeof(struct ether_arp)) == sizeof(struct ether_arp));
-                test_arp_header(&arp);
 
                 /* PROBE */
                 sd_event_run(e, (uint64_t) -1);
                 assert_se(read(test_fd[1], &arp, sizeof(struct ether_arp)) == sizeof(struct ether_arp));
-                test_arp_header(&arp);
 
                 sd_event_run(e, (uint64_t) -1);
                 assert_se(basic_request_handler_bind == 1);
@@ -215,11 +197,13 @@ static void test_basic_request(sd_event *e) {
 int main(int argc, char *argv[]) {
         _cleanup_event_unref_ sd_event *e = NULL;
 
+        log_set_max_level(LOG_DEBUG);
+        log_parse_environment();
+        log_open();
+
         assert_se(sd_event_new(&e) >= 0);
 
         test_public_api_setters(e);
-        test_arp_probe();
-        test_arp_announce();
         test_basic_request(e);
 
         return 0;
diff --git a/src/network/networkd-ipv4ll.c b/src/network/networkd-ipv4ll.c
index 0a27a30278..1c34f55b4b 100644
--- a/src/network/networkd-ipv4ll.c
+++ b/src/network/networkd-ipv4ll.c
@@ -195,10 +195,7 @@ static void ipv4ll_handler(sd_ipv4ll *ll, int event, void *userdata){
                         }
                         break;
                 default:
-                        if (event < 0)
-                                log_link_warning(link, "IPv4 link-local error: %s", strerror(-event));
-                        else
-                                log_link_warning(link, "IPv4 link-local unknown event: %d", event);
+                        log_link_warning(link, "IPv4 link-local unknown event: %d", event);
                         break;
         }
 }
@@ -218,7 +215,9 @@ int ipv4ll_configure(Link *link) {
         if (link->udev_device) {
                 r = net_get_unique_predictable_data(link->udev_device, seed);
                 if (r >= 0) {
-                        r = sd_ipv4ll_set_address_seed(link->ipv4ll, seed);
+                        assert_cc(sizeof(unsigned) <= 8);
+
+                        r = sd_ipv4ll_set_address_seed(link->ipv4ll, *(unsigned *)seed);
                         if (r < 0)
                                 return r;
                 }
diff --git a/src/systemd/sd-ipv4acd.h b/src/systemd/sd-ipv4acd.h
new file mode 100644
index 0000000000..8844ae848d
--- /dev/null
+++ b/src/systemd/sd-ipv4acd.h
@@ -0,0 +1,55 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+#ifndef foosdipv4acdfoo
+#define foosdipv4acdfoo
+
+/***
+  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
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <stdbool.h>
+#include <netinet/in.h>
+#include <net/ethernet.h>
+
+#include "sd-event.h"
+
+enum {
+        IPV4ACD_EVENT_STOP           = 0,
+        IPV4ACD_EVENT_BIND           = 1,
+        IPV4ACD_EVENT_CONFLICT       = 2,
+};
+
+typedef struct sd_ipv4acd sd_ipv4acd;
+typedef void (*sd_ipv4acd_cb_t)(sd_ipv4acd *ll, int event, void *userdata);
+
+int sd_ipv4acd_detach_event(sd_ipv4acd *ll);
+int sd_ipv4acd_attach_event(sd_ipv4acd *ll, sd_event *event, int priority);
+int sd_ipv4acd_get_address(sd_ipv4acd *ll, struct in_addr *address);
+int sd_ipv4acd_set_callback(sd_ipv4acd *ll, sd_ipv4acd_cb_t cb, void *userdata);
+int sd_ipv4acd_set_mac(sd_ipv4acd *ll, const struct ether_addr *addr);
+int sd_ipv4acd_set_index(sd_ipv4acd *ll, int interface_index);
+int sd_ipv4acd_set_address(sd_ipv4acd *ll, const struct in_addr *address);
+bool sd_ipv4acd_is_running(sd_ipv4acd *ll);
+int sd_ipv4acd_start(sd_ipv4acd *ll);
+int sd_ipv4acd_stop(sd_ipv4acd *ll);
+sd_ipv4acd *sd_ipv4acd_ref(sd_ipv4acd *ll);
+sd_ipv4acd *sd_ipv4acd_unref(sd_ipv4acd *ll);
+int sd_ipv4acd_new (sd_ipv4acd **ret);
+
+#endif
diff --git a/src/systemd/sd-ipv4ll.h b/src/systemd/sd-ipv4ll.h
index d017158154..9581e99d31 100644
--- a/src/systemd/sd-ipv4ll.h
+++ b/src/systemd/sd-ipv4ll.h
@@ -43,7 +43,7 @@ int sd_ipv4ll_get_address(sd_ipv4ll *ll, struct in_addr *address);
 int sd_ipv4ll_set_callback(sd_ipv4ll *ll, sd_ipv4ll_cb_t cb, void *userdata);
 int sd_ipv4ll_set_mac(sd_ipv4ll *ll, const struct ether_addr *addr);
 int sd_ipv4ll_set_index(sd_ipv4ll *ll, int interface_index);
-int sd_ipv4ll_set_address_seed(sd_ipv4ll *ll, uint8_t seed[8]);
+int sd_ipv4ll_set_address_seed(sd_ipv4ll *ll, unsigned seed);
 bool sd_ipv4ll_is_running(sd_ipv4ll *ll);
 int sd_ipv4ll_start(sd_ipv4ll *ll);
 int sd_ipv4ll_stop(sd_ipv4ll *ll);