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-rw-r--r--src/libsystemd-network/sd-ipv4acd.c611
1 files changed, 611 insertions, 0 deletions
diff --git a/src/libsystemd-network/sd-ipv4acd.c b/src/libsystemd-network/sd-ipv4acd.c
new file mode 100644
index 0000000..9b11b2f
--- /dev/null
+++ b/src/libsystemd-network/sd-ipv4acd.c
@@ -0,0 +1,611 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/***
+ Copyright © 2014 Axis Communications AB. All rights reserved.
+***/
+
+#include <arpa/inet.h>
+#include <errno.h>
+#include <netinet/if_ether.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "sd-ipv4acd.h"
+
+#include "alloc-util.h"
+#include "arp-util.h"
+#include "ether-addr-util.h"
+#include "event-util.h"
+#include "fd-util.h"
+#include "in-addr-util.h"
+#include "memory-util.h"
+#include "network-common.h"
+#include "random-util.h"
+#include "siphash24.h"
+#include "string-table.h"
+#include "string-util.h"
+#include "time-util.h"
+
+/* Constants from the RFC */
+#define PROBE_WAIT_USEC (1U * USEC_PER_SEC)
+#define PROBE_NUM 3U
+#define PROBE_MIN_USEC (1U * USEC_PER_SEC)
+#define PROBE_MAX_USEC (2U * USEC_PER_SEC)
+#define ANNOUNCE_WAIT_USEC (2U * USEC_PER_SEC)
+#define ANNOUNCE_NUM 2U
+#define ANNOUNCE_INTERVAL_USEC (2U * USEC_PER_SEC)
+#define MAX_CONFLICTS 10U
+#define RATE_LIMIT_INTERVAL_USEC (60U * USEC_PER_SEC)
+#define DEFEND_INTERVAL_USEC (10U * USEC_PER_SEC)
+
+typedef enum IPv4ACDState {
+ IPV4ACD_STATE_INIT,
+ IPV4ACD_STATE_STARTED,
+ IPV4ACD_STATE_WAITING_PROBE,
+ IPV4ACD_STATE_PROBING,
+ IPV4ACD_STATE_WAITING_ANNOUNCE,
+ IPV4ACD_STATE_ANNOUNCING,
+ IPV4ACD_STATE_RUNNING,
+ _IPV4ACD_STATE_MAX,
+ _IPV4ACD_STATE_INVALID = -EINVAL,
+} IPv4ACDState;
+
+struct sd_ipv4acd {
+ unsigned n_ref;
+
+ IPv4ACDState state;
+ int ifindex;
+ int fd;
+
+ char *ifname;
+ unsigned n_iteration;
+ unsigned n_conflict;
+
+ sd_event_source *receive_message_event_source;
+ sd_event_source *timer_event_source;
+
+ usec_t defend_window;
+ struct in_addr address;
+
+ /* External */
+ struct ether_addr mac_addr;
+
+ sd_event *event;
+ int event_priority;
+ sd_ipv4acd_callback_t callback;
+ void *userdata;
+ sd_ipv4acd_check_mac_callback_t check_mac_callback;
+ void *check_mac_userdata;
+};
+
+#define log_ipv4acd_errno(acd, error, fmt, ...) \
+ log_interface_prefix_full_errno( \
+ "IPv4ACD: ", \
+ sd_ipv4acd, acd, \
+ error, fmt, ##__VA_ARGS__)
+#define log_ipv4acd(acd, fmt, ...) \
+ log_interface_prefix_full_errno_zerook( \
+ "IPv4ACD: ", \
+ sd_ipv4acd, acd, \
+ 0, fmt, ##__VA_ARGS__)
+
+static const char * const ipv4acd_state_table[_IPV4ACD_STATE_MAX] = {
+ [IPV4ACD_STATE_INIT] = "init",
+ [IPV4ACD_STATE_STARTED] = "started",
+ [IPV4ACD_STATE_WAITING_PROBE] = "waiting-probe",
+ [IPV4ACD_STATE_PROBING] = "probing",
+ [IPV4ACD_STATE_WAITING_ANNOUNCE] = "waiting-announce",
+ [IPV4ACD_STATE_ANNOUNCING] = "announcing",
+ [IPV4ACD_STATE_RUNNING] = "running",
+};
+
+DEFINE_PRIVATE_STRING_TABLE_LOOKUP_TO_STRING(ipv4acd_state, IPv4ACDState);
+
+static void ipv4acd_set_state(sd_ipv4acd *acd, IPv4ACDState st, bool reset_counter) {
+ assert(acd);
+ assert(st < _IPV4ACD_STATE_MAX);
+
+ if (st != acd->state)
+ log_ipv4acd(acd, "%s -> %s", ipv4acd_state_to_string(acd->state), ipv4acd_state_to_string(st));
+
+ if (st == acd->state && !reset_counter)
+ acd->n_iteration++;
+ else {
+ acd->state = st;
+ acd->n_iteration = 0;
+ }
+}
+
+static void ipv4acd_reset(sd_ipv4acd *acd) {
+ assert(acd);
+
+ (void) event_source_disable(acd->timer_event_source);
+ acd->receive_message_event_source = sd_event_source_disable_unref(acd->receive_message_event_source);
+
+ acd->fd = safe_close(acd->fd);
+
+ ipv4acd_set_state(acd, IPV4ACD_STATE_INIT, true);
+}
+
+static sd_ipv4acd *ipv4acd_free(sd_ipv4acd *acd) {
+ assert(acd);
+
+ ipv4acd_reset(acd);
+ sd_event_source_unref(acd->timer_event_source);
+ sd_ipv4acd_detach_event(acd);
+ free(acd->ifname);
+ return mfree(acd);
+}
+
+DEFINE_TRIVIAL_REF_UNREF_FUNC(sd_ipv4acd, sd_ipv4acd, ipv4acd_free);
+
+int sd_ipv4acd_new(sd_ipv4acd **ret) {
+ _cleanup_(sd_ipv4acd_unrefp) sd_ipv4acd *acd = NULL;
+
+ assert_return(ret, -EINVAL);
+
+ acd = new(sd_ipv4acd, 1);
+ if (!acd)
+ return -ENOMEM;
+
+ *acd = (sd_ipv4acd) {
+ .n_ref = 1,
+ .state = IPV4ACD_STATE_INIT,
+ .ifindex = -1,
+ .fd = -1,
+ };
+
+ *ret = TAKE_PTR(acd);
+
+ return 0;
+}
+
+static void ipv4acd_client_notify(sd_ipv4acd *acd, int event) {
+ assert(acd);
+
+ if (!acd->callback)
+ return;
+
+ acd->callback(acd, event, acd->userdata);
+}
+
+int sd_ipv4acd_stop(sd_ipv4acd *acd) {
+ IPv4ACDState old_state;
+
+ if (!acd)
+ return 0;
+
+ old_state = acd->state;
+
+ ipv4acd_reset(acd);
+
+ if (old_state == IPV4ACD_STATE_INIT)
+ return 0;
+
+ log_ipv4acd(acd, "STOPPED");
+
+ ipv4acd_client_notify(acd, SD_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 *acd, usec_t usec, usec_t random_usec) {
+ usec_t next_timeout, time_now;
+
+ assert(acd);
+
+ next_timeout = usec;
+
+ if (random_usec > 0)
+ next_timeout += (usec_t) random_u64() % random_usec;
+
+ assert_se(sd_event_now(acd->event, CLOCK_BOOTTIME, &time_now) >= 0);
+
+ return event_reset_time(acd->event, &acd->timer_event_source,
+ CLOCK_BOOTTIME,
+ time_now + next_timeout, 0,
+ ipv4acd_on_timeout, acd,
+ acd->event_priority, "ipv4acd-timer", true);
+}
+
+static int ipv4acd_on_timeout(sd_event_source *s, uint64_t usec, void *userdata) {
+ sd_ipv4acd *acd = ASSERT_PTR(userdata);
+ int r = 0;
+
+ switch (acd->state) {
+
+ case IPV4ACD_STATE_STARTED:
+ acd->defend_window = 0;
+
+ ipv4acd_set_state(acd, IPV4ACD_STATE_WAITING_PROBE, true);
+
+ if (acd->n_conflict >= MAX_CONFLICTS) {
+ log_ipv4acd(acd, "Max conflicts reached, delaying by %s",
+ FORMAT_TIMESPAN(RATE_LIMIT_INTERVAL_USEC, 0));
+ r = ipv4acd_set_next_wakeup(acd, RATE_LIMIT_INTERVAL_USEC, PROBE_WAIT_USEC);
+ } else
+ r = ipv4acd_set_next_wakeup(acd, 0, PROBE_WAIT_USEC);
+ if (r < 0)
+ goto fail;
+
+ break;
+
+ case IPV4ACD_STATE_WAITING_PROBE:
+ case IPV4ACD_STATE_PROBING:
+ /* Send a probe */
+ r = arp_send_probe(acd->fd, acd->ifindex, &acd->address, &acd->mac_addr);
+ if (r < 0) {
+ log_ipv4acd_errno(acd, r, "Failed to send ARP probe: %m");
+ goto fail;
+ }
+
+ log_ipv4acd(acd, "Probing "IPV4_ADDRESS_FMT_STR, IPV4_ADDRESS_FMT_VAL(acd->address));
+
+ if (acd->n_iteration < PROBE_NUM - 2) {
+ ipv4acd_set_state(acd, IPV4ACD_STATE_PROBING, false);
+
+ r = ipv4acd_set_next_wakeup(acd, PROBE_MIN_USEC, (PROBE_MAX_USEC-PROBE_MIN_USEC));
+ if (r < 0)
+ goto fail;
+ } else {
+ ipv4acd_set_state(acd, IPV4ACD_STATE_WAITING_ANNOUNCE, true);
+
+ r = ipv4acd_set_next_wakeup(acd, ANNOUNCE_WAIT_USEC, 0);
+ if (r < 0)
+ goto fail;
+ }
+
+ break;
+
+ case IPV4ACD_STATE_ANNOUNCING:
+ if (acd->n_iteration >= ANNOUNCE_NUM - 1) {
+ ipv4acd_set_state(acd, IPV4ACD_STATE_RUNNING, false);
+ break;
+ }
+
+ _fallthrough_;
+ case IPV4ACD_STATE_WAITING_ANNOUNCE:
+ /* Send announcement packet */
+ r = arp_send_announcement(acd->fd, acd->ifindex, &acd->address, &acd->mac_addr);
+ if (r < 0) {
+ log_ipv4acd_errno(acd, r, "Failed to send ARP announcement: %m");
+ goto fail;
+ }
+
+ log_ipv4acd(acd, "Announcing "IPV4_ADDRESS_FMT_STR, IPV4_ADDRESS_FMT_VAL(acd->address));
+
+ ipv4acd_set_state(acd, IPV4ACD_STATE_ANNOUNCING, false);
+
+ r = ipv4acd_set_next_wakeup(acd, ANNOUNCE_INTERVAL_USEC, 0);
+ if (r < 0)
+ goto fail;
+
+ if (acd->n_iteration == 0) {
+ acd->n_conflict = 0;
+ ipv4acd_client_notify(acd, SD_IPV4ACD_EVENT_BIND);
+ }
+
+ break;
+
+ default:
+ assert_not_reached();
+ }
+
+ return 0;
+
+fail:
+ sd_ipv4acd_stop(acd);
+ return 0;
+}
+
+static bool ipv4acd_arp_conflict(sd_ipv4acd *acd, const struct ether_arp *arp, bool announced) {
+ assert(acd);
+ assert(arp);
+
+ /* RFC 5227 section 2.1.1.
+ * "the host receives any ARP packet (Request *or* Reply) on the interface where the probe is
+ * being performed, where the packet's 'sender IP address' is the address being probed for,
+ * then the host MUST treat this address as being in use by some other host" */
+ if (memcmp(arp->arp_spa, &acd->address, sizeof(struct in_addr)) == 0)
+ return true;
+
+ if (announced)
+ /* the TPA matched instead of SPA, this is not a conflict */
+ return false;
+
+ /* "any ARP Probe where the packet's 'target IP address' is the address being probed for, and
+ * the packet's 'sender hardware address' is not the hardware address of any of the host's
+ * interfaces, then the host SHOULD similarly treat this as an address conflict" */
+ if (arp->ea_hdr.ar_op != htobe16(ARPOP_REQUEST))
+ return false; /* not ARP Request, ignoring. */
+ if (memeqzero(arp->arp_spa, sizeof(struct in_addr)) == 0)
+ return false; /* not ARP Probe, ignoring. */
+ if (memcmp(arp->arp_tpa, &acd->address, sizeof(struct in_addr)) != 0)
+ return false; /* target IP address does not match, BPF code is broken? */
+
+ if (acd->check_mac_callback &&
+ acd->check_mac_callback(acd, (const struct ether_addr*) arp->arp_sha, acd->check_mac_userdata) > 0)
+ /* sender hardware is one of the host's interfaces, ignoring. */
+ return false;
+
+ return true; /* conflict! */
+}
+
+static void ipv4acd_on_conflict(sd_ipv4acd *acd) {
+ assert(acd);
+
+ acd->n_conflict++;
+
+ log_ipv4acd(acd, "Conflict on "IPV4_ADDRESS_FMT_STR" (%u)", IPV4_ADDRESS_FMT_VAL(acd->address), acd->n_conflict);
+
+ ipv4acd_reset(acd);
+ ipv4acd_client_notify(acd, SD_IPV4ACD_EVENT_CONFLICT);
+}
+
+static int ipv4acd_on_packet(
+ sd_event_source *s,
+ int fd,
+ uint32_t revents,
+ void *userdata) {
+
+ sd_ipv4acd *acd = ASSERT_PTR(userdata);
+ struct ether_arp packet;
+ ssize_t n;
+ int r;
+
+ assert(s);
+ assert(fd >= 0);
+
+ n = recv(fd, &packet, sizeof(struct ether_arp), 0);
+ if (n < 0) {
+ if (ERRNO_IS_TRANSIENT(errno) || ERRNO_IS_DISCONNECT(errno))
+ return 0;
+
+ log_ipv4acd_errno(acd, errno, "Failed to read ARP packet: %m");
+ goto fail;
+ }
+ if ((size_t) n != sizeof(struct ether_arp)) {
+ log_ipv4acd(acd, "Ignoring too short ARP packet.");
+ return 0;
+ }
+
+ switch (acd->state) {
+
+ case IPV4ACD_STATE_ANNOUNCING:
+ case IPV4ACD_STATE_RUNNING:
+
+ if (ipv4acd_arp_conflict(acd, &packet, true)) {
+ usec_t ts;
+
+ assert_se(sd_event_now(acd->event, CLOCK_BOOTTIME, &ts) >= 0);
+
+ /* Defend address */
+ if (ts > acd->defend_window) {
+ acd->defend_window = ts + DEFEND_INTERVAL_USEC;
+ r = arp_send_announcement(acd->fd, acd->ifindex, &acd->address, &acd->mac_addr);
+ if (r < 0) {
+ log_ipv4acd_errno(acd, r, "Failed to send ARP announcement: %m");
+ goto fail;
+ }
+
+ log_ipv4acd(acd, "Defending "IPV4_ADDRESS_FMT_STR, IPV4_ADDRESS_FMT_VAL(acd->address));
+
+ } else
+ ipv4acd_on_conflict(acd);
+ }
+ break;
+
+ case IPV4ACD_STATE_WAITING_PROBE:
+ case IPV4ACD_STATE_PROBING:
+ case IPV4ACD_STATE_WAITING_ANNOUNCE:
+ if (ipv4acd_arp_conflict(acd, &packet, false))
+ ipv4acd_on_conflict(acd);
+ break;
+
+ default:
+ assert_not_reached();
+ }
+
+ return 0;
+
+fail:
+ sd_ipv4acd_stop(acd);
+ return 0;
+}
+
+int sd_ipv4acd_set_ifindex(sd_ipv4acd *acd, int ifindex) {
+ assert_return(acd, -EINVAL);
+ assert_return(ifindex > 0, -EINVAL);
+ assert_return(acd->state == IPV4ACD_STATE_INIT, -EBUSY);
+
+ acd->ifindex = ifindex;
+
+ return 0;
+}
+
+int sd_ipv4acd_get_ifindex(sd_ipv4acd *acd) {
+ if (!acd)
+ return -EINVAL;
+
+ return acd->ifindex;
+}
+
+int sd_ipv4acd_set_ifname(sd_ipv4acd *acd, const char *ifname) {
+ assert_return(acd, -EINVAL);
+ assert_return(ifname, -EINVAL);
+
+ if (!ifname_valid_full(ifname, IFNAME_VALID_ALTERNATIVE))
+ return -EINVAL;
+
+ return free_and_strdup(&acd->ifname, ifname);
+}
+
+int sd_ipv4acd_get_ifname(sd_ipv4acd *acd, const char **ret) {
+ int r;
+
+ assert_return(acd, -EINVAL);
+
+ r = get_ifname(acd->ifindex, &acd->ifname);
+ if (r < 0)
+ return r;
+
+ if (ret)
+ *ret = acd->ifname;
+
+ return 0;
+}
+
+int sd_ipv4acd_set_mac(sd_ipv4acd *acd, const struct ether_addr *addr) {
+ int r;
+
+ assert_return(acd, -EINVAL);
+ assert_return(addr, -EINVAL);
+ assert_return(!ether_addr_is_null(addr), -EINVAL);
+
+ acd->mac_addr = *addr;
+
+ if (!sd_ipv4acd_is_running(acd))
+ return 0;
+
+ assert(acd->fd >= 0);
+ r = arp_update_filter(acd->fd, &acd->address, &acd->mac_addr);
+ if (r < 0) {
+ ipv4acd_reset(acd);
+ return r;
+ }
+
+ return 0;
+}
+
+int sd_ipv4acd_detach_event(sd_ipv4acd *acd) {
+ assert_return(acd, -EINVAL);
+
+ acd->event = sd_event_unref(acd->event);
+
+ return 0;
+}
+
+int sd_ipv4acd_attach_event(sd_ipv4acd *acd, sd_event *event, int64_t priority) {
+ int r;
+
+ assert_return(acd, -EINVAL);
+ assert_return(!acd->event, -EBUSY);
+
+ if (event)
+ acd->event = sd_event_ref(event);
+ else {
+ r = sd_event_default(&acd->event);
+ if (r < 0)
+ return r;
+ }
+
+ acd->event_priority = priority;
+
+ return 0;
+}
+
+int sd_ipv4acd_set_callback(sd_ipv4acd *acd, sd_ipv4acd_callback_t cb, void *userdata) {
+ assert_return(acd, -EINVAL);
+
+ acd->callback = cb;
+ acd->userdata = userdata;
+
+ return 0;
+}
+
+int sd_ipv4acd_set_check_mac_callback(sd_ipv4acd *acd, sd_ipv4acd_check_mac_callback_t cb, void *userdata) {
+ assert_return(acd, -EINVAL);
+
+ acd->check_mac_callback = cb;
+ acd->check_mac_userdata = userdata;
+ return 0;
+}
+
+int sd_ipv4acd_set_address(sd_ipv4acd *acd, const struct in_addr *address) {
+ int r;
+
+ assert_return(acd, -EINVAL);
+ assert_return(address, -EINVAL);
+ assert_return(in4_addr_is_set(address), -EINVAL);
+
+ if (in4_addr_equal(&acd->address, address))
+ return 0;
+
+ acd->address = *address;
+
+ if (!sd_ipv4acd_is_running(acd))
+ return 0;
+
+ assert(acd->fd >= 0);
+ r = arp_update_filter(acd->fd, &acd->address, &acd->mac_addr);
+ if (r < 0)
+ goto fail;
+
+ r = ipv4acd_set_next_wakeup(acd, 0, 0);
+ if (r < 0)
+ goto fail;
+
+ ipv4acd_set_state(acd, IPV4ACD_STATE_STARTED, true);
+ return 0;
+
+fail:
+ ipv4acd_reset(acd);
+ return r;
+}
+
+int sd_ipv4acd_get_address(sd_ipv4acd *acd, struct in_addr *address) {
+ assert_return(acd, -EINVAL);
+ assert_return(address, -EINVAL);
+
+ *address = acd->address;
+
+ return 0;
+}
+
+int sd_ipv4acd_is_running(sd_ipv4acd *acd) {
+ assert_return(acd, false);
+
+ return acd->state != IPV4ACD_STATE_INIT;
+}
+
+int sd_ipv4acd_start(sd_ipv4acd *acd, bool reset_conflicts) {
+ int r;
+
+ assert_return(acd, -EINVAL);
+ assert_return(acd->event, -EINVAL);
+ assert_return(acd->ifindex > 0, -EINVAL);
+ assert_return(in4_addr_is_set(&acd->address), -EINVAL);
+ assert_return(!ether_addr_is_null(&acd->mac_addr), -EINVAL);
+ assert_return(acd->state == IPV4ACD_STATE_INIT, -EBUSY);
+
+ r = arp_network_bind_raw_socket(acd->ifindex, &acd->address, &acd->mac_addr);
+ if (r < 0)
+ return r;
+
+ close_and_replace(acd->fd, r);
+
+ if (reset_conflicts)
+ acd->n_conflict = 0;
+
+ r = sd_event_add_io(acd->event, &acd->receive_message_event_source, acd->fd, EPOLLIN, ipv4acd_on_packet, acd);
+ if (r < 0)
+ goto fail;
+
+ r = sd_event_source_set_priority(acd->receive_message_event_source, acd->event_priority);
+ if (r < 0)
+ goto fail;
+
+ (void) sd_event_source_set_description(acd->receive_message_event_source, "ipv4acd-receive-message");
+
+ r = ipv4acd_set_next_wakeup(acd, 0, 0);
+ if (r < 0)
+ goto fail;
+
+ ipv4acd_set_state(acd, IPV4ACD_STATE_STARTED, true);
+ return 0;
+
+fail:
+ ipv4acd_reset(acd);
+ return r;
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-07-11 20:49:29 +0000