| /* SPDX-License-Identifier: LGPL-2.1+ */ |
| /*** |
| 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 "list.h" |
| #include "random-util.h" |
| #include "siphash24.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 = -1 |
| } IPv4ACDState; |
| |
| struct sd_ipv4acd { |
| unsigned n_ref; |
| |
| IPv4ACDState state; |
| int ifindex; |
| int fd; |
| |
| unsigned n_iteration; |
| unsigned n_conflict; |
| |
| sd_event_source *receive_message_event_source; |
| sd_event_source *timer_event_source; |
| |
| usec_t defend_window; |
| be32_t address; |
| |
| /* External */ |
| struct ether_addr mac_addr; |
| |
| sd_event *event; |
| int event_priority; |
| sd_ipv4acd_callback_t callback; |
| void* userdata; |
| }; |
| |
| #define log_ipv4acd_errno(acd, error, fmt, ...) log_internal(LOG_DEBUG, error, PROJECT_FILE, __LINE__, __func__, "IPV4ACD: " fmt, ##__VA_ARGS__) |
| #define log_ipv4acd(acd, fmt, ...) log_ipv4acd_errno(acd, 0, fmt, ##__VA_ARGS__) |
| |
| static void ipv4acd_set_state(sd_ipv4acd *acd, IPv4ACDState st, bool reset_counter) { |
| assert(acd); |
| assert(st < _IPV4ACD_STATE_MAX); |
| |
| 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_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); |
| |
| acd->timer_event_source = sd_event_source_unref(acd->timer_event_source); |
| |
| ipv4acd_reset(acd); |
| sd_ipv4acd_detach_event(acd); |
| |
| 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_or_monotonic(), &time_now) >= 0); |
| |
| return event_reset_time(acd->event, &acd->timer_event_source, |
| clock_boottime_or_monotonic(), |
| time_now + next_timeout, 0, |
| ipv4acd_on_timeout, acd, |
| acd->event_priority, "ipv4acd-timer", true); |
| } |
| |
| static bool ipv4acd_arp_conflict(sd_ipv4acd *acd, struct ether_arp *arp) { |
| assert(acd); |
| assert(arp); |
| |
| /* see the BPF */ |
| if (memcmp(arp->arp_spa, &acd->address, sizeof(acd->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 *acd = userdata; |
| int r = 0; |
| |
| assert(acd); |
| |
| switch (acd->state) { |
| |
| case IPV4ACD_STATE_STARTED: |
| ipv4acd_set_state(acd, IPV4ACD_STATE_WAITING_PROBE, true); |
| |
| if (acd->n_conflict >= MAX_CONFLICTS) { |
| char ts[FORMAT_TIMESPAN_MAX]; |
| log_ipv4acd(acd, "Max conflicts reached, delaying by %s", format_timespan(ts, sizeof(ts), RATE_LIMIT_INTERVAL_USEC, 0)); |
| |
| r = ipv4acd_set_next_wakeup(acd, RATE_LIMIT_INTERVAL_USEC, PROBE_WAIT_USEC); |
| if (r < 0) |
| goto fail; |
| } 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; |
| } else { |
| _cleanup_free_ char *address = NULL; |
| union in_addr_union addr = { .in.s_addr = acd->address }; |
| |
| (void) in_addr_to_string(AF_INET, &addr, &address); |
| log_ipv4acd(acd, "Probing %s", strna(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; |
| } else |
| log_ipv4acd(acd, "ANNOUNCE"); |
| |
| 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("Invalid state."); |
| } |
| |
| return 0; |
| |
| fail: |
| sd_ipv4acd_stop(acd); |
| return 0; |
| } |
| |
| static void ipv4acd_on_conflict(sd_ipv4acd *acd) { |
| _cleanup_free_ char *address = NULL; |
| union in_addr_union addr = { .in.s_addr = acd->address }; |
| |
| assert(acd); |
| |
| acd->n_conflict++; |
| |
| (void) in_addr_to_string(AF_INET, &addr, &address); |
| log_ipv4acd(acd, "Conflict on %s (%u)", strna(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 = userdata; |
| struct ether_arp packet; |
| ssize_t n; |
| int r; |
| |
| assert(s); |
| assert(acd); |
| assert(fd >= 0); |
| |
| n = recv(fd, &packet, sizeof(struct ether_arp), 0); |
| if (n < 0) { |
| if (IN_SET(errno, EAGAIN, EINTR)) |
| 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)) { |
| usec_t ts; |
| |
| assert_se(sd_event_now(acd->event, clock_boottime_or_monotonic(), &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; |
| } else |
| log_ipv4acd(acd, "DEFEND"); |
| |
| } else |
| ipv4acd_on_conflict(acd); |
| } |
| 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(acd); |
| break; |
| |
| default: |
| assert_not_reached("Invalid state."); |
| } |
| |
| 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_set_mac(sd_ipv4acd *acd, const struct ether_addr *addr) { |
| assert_return(acd, -EINVAL); |
| assert_return(addr, -EINVAL); |
| assert_return(acd->state == IPV4ACD_STATE_INIT, -EBUSY); |
| |
| acd->mac_addr = *addr; |
| |
| 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_address(sd_ipv4acd *acd, const struct in_addr *address) { |
| assert_return(acd, -EINVAL); |
| assert_return(address, -EINVAL); |
| assert_return(acd->state == IPV4ACD_STATE_INIT, -EBUSY); |
| |
| acd->address = address->s_addr; |
| |
| return 0; |
| } |
| |
| int sd_ipv4acd_get_address(sd_ipv4acd *acd, struct in_addr *address) { |
| assert_return(acd, -EINVAL); |
| assert_return(address, -EINVAL); |
| |
| address->s_addr = 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(acd->address != 0, -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); |
| acd->defend_window = 0; |
| |
| 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; |
| } |