diff options
Diffstat (limited to '')
| -rw-r--r-- | src/libsystemd-network/sd-ipv4acd.c | 501 |
1 files changed, 501 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..2e1e46c --- /dev/null +++ b/src/libsystemd-network/sd-ipv4acd.c @@ -0,0 +1,501 @@ +/* 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 "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; +} |