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Merge pull request #4512 from pfl/ndisc_exponential_backoff
Ndisc exponential backoff
This commit is contained in:
Lennart Poettering
GitHub
commit
4af273d149
@ -23,6 +23,10 @@
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#include "sd-ndisc.h"
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#define NDISC_ROUTER_SOLICITATION_INTERVAL (4U * USEC_PER_SEC)
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#define NDISC_MAX_ROUTER_SOLICITATION_INTERVAL (3600U * USEC_PER_SEC)
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#define NDISC_MAX_ROUTER_SOLICITATIONS 3U
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struct sd_ndisc {
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unsigned n_ref;
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@ -38,8 +42,9 @@ struct sd_ndisc {
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sd_event_source *recv_event_source;
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sd_event_source *timeout_event_source;
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sd_event_source *timeout_no_ra;
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unsigned nd_sent;
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usec_t retransmit_time;
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sd_ndisc_callback_t callback;
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void *userdata;
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@ -28,12 +28,12 @@
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#include "in-addr-util.h"
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#include "ndisc-internal.h"
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#include "ndisc-router.h"
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#include "random-util.h"
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#include "socket-util.h"
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#include "string-util.h"
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#include "util.h"
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#define NDISC_ROUTER_SOLICITATION_INTERVAL (4U * USEC_PER_SEC)
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#define NDISC_MAX_ROUTER_SOLICITATIONS 3U
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#define NDISC_TIMEOUT_NO_RA_USEC (NDISC_ROUTER_SOLICITATION_INTERVAL * NDISC_MAX_ROUTER_SOLICITATIONS)
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static void ndisc_callback(sd_ndisc *ndisc, sd_ndisc_event event, sd_ndisc_router *rt) {
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assert(ndisc);
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@ -129,9 +129,10 @@ static int ndisc_reset(sd_ndisc *nd) {
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assert(nd);
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nd->timeout_event_source = sd_event_source_unref(nd->timeout_event_source);
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nd->timeout_no_ra = sd_event_source_unref(nd->timeout_no_ra);
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nd->retransmit_time = 0;
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nd->recv_event_source = sd_event_source_unref(nd->recv_event_source);
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nd->fd = safe_close(nd->fd);
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nd->nd_sent = 0;
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return 0;
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}
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@ -264,19 +265,52 @@ static int ndisc_recv(sd_event_source *s, int fd, uint32_t revents, void *userda
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return ndisc_handle_datagram(nd, rt);
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}
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static usec_t ndisc_timeout_compute_random(usec_t val) {
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/* compute a time that is random within ±10% of the given value */
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return val - val / 10 +
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(random_u64() % (2 * USEC_PER_SEC)) * val / 10 / USEC_PER_SEC;
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}
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static int ndisc_timeout(sd_event_source *s, uint64_t usec, void *userdata) {
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sd_ndisc *nd = userdata;
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usec_t time_now, next_timeout;
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usec_t time_now;
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int r;
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char time_string[FORMAT_TIMESPAN_MAX];
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assert(s);
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assert(nd);
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assert(nd->event);
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if (nd->nd_sent >= NDISC_MAX_ROUTER_SOLICITATIONS) {
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nd->timeout_event_source = sd_event_source_unref(nd->timeout_event_source);
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ndisc_callback(nd, SD_NDISC_EVENT_TIMEOUT, NULL);
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return 0;
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assert_se(sd_event_now(nd->event, clock_boottime_or_monotonic(), &time_now) >= 0);
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nd->timeout_event_source = sd_event_source_unref(nd->timeout_event_source);
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if (!nd->retransmit_time)
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nd->retransmit_time = ndisc_timeout_compute_random(NDISC_ROUTER_SOLICITATION_INTERVAL);
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else {
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if (nd->retransmit_time > NDISC_MAX_ROUTER_SOLICITATION_INTERVAL / 2)
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nd->retransmit_time = ndisc_timeout_compute_random(NDISC_MAX_ROUTER_SOLICITATION_INTERVAL);
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else
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nd->retransmit_time += ndisc_timeout_compute_random(nd->retransmit_time);
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}
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r = sd_event_add_time(nd->event, &nd->timeout_event_source,
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clock_boottime_or_monotonic(),
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time_now + nd->retransmit_time,
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10 * USEC_PER_MSEC, ndisc_timeout, nd);
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if (r < 0)
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goto fail;
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r = sd_event_source_set_priority(nd->timeout_event_source, nd->event_priority);
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if (r < 0)
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goto fail;
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(void) sd_event_source_set_description(nd->timeout_event_source, "ndisc-timeout-no-ra");
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r = sd_event_source_set_enabled(nd->timeout_event_source, SD_EVENT_ONESHOT);
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if (r < 0) {
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log_ndisc_errno(r, "Error reenabling timer: %m");
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goto fail;
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}
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r = icmp6_send_router_solicitation(nd->fd, &nd->mac_addr);
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@ -285,23 +319,9 @@ static int ndisc_timeout(sd_event_source *s, uint64_t usec, void *userdata) {
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goto fail;
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}
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log_ndisc("Sent Router Solicitation");
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nd->nd_sent++;
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assert_se(sd_event_now(nd->event, clock_boottime_or_monotonic(), &time_now) >= 0);
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next_timeout = time_now + NDISC_ROUTER_SOLICITATION_INTERVAL;
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r = sd_event_source_set_time(nd->timeout_event_source, next_timeout);
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if (r < 0) {
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log_ndisc_errno(r, "Error updating timer: %m");
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goto fail;
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}
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r = sd_event_source_set_enabled(nd->timeout_event_source, SD_EVENT_ONESHOT);
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if (r < 0) {
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log_ndisc_errno(r, "Error reenabling timer: %m");
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goto fail;
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}
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log_ndisc("Sent Router Solicitation, next solicitation in %s",
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format_timespan(time_string, FORMAT_TIMESPAN_MAX,
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nd->retransmit_time, USEC_PER_SEC));
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return 0;
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@ -310,6 +330,20 @@ fail:
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return 0;
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}
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static int ndisc_timeout_no_ra(sd_event_source *s, uint64_t usec, void *userdata) {
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sd_ndisc *nd = userdata;
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assert(s);
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assert(nd);
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log_ndisc("No RA received before link confirmation timeout");
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nd->timeout_no_ra = sd_event_source_unref(nd->timeout_no_ra);
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ndisc_callback(nd, SD_NDISC_EVENT_TIMEOUT, NULL);
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return 0;
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}
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_public_ int sd_ndisc_stop(sd_ndisc *nd) {
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assert_return(nd, -EINVAL);
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@ -324,6 +358,7 @@ _public_ int sd_ndisc_stop(sd_ndisc *nd) {
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_public_ int sd_ndisc_start(sd_ndisc *nd) {
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int r;
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usec_t time_now;
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assert_return(nd, -EINVAL);
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assert_return(nd->event, -EINVAL);
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@ -335,6 +370,10 @@ _public_ int sd_ndisc_start(sd_ndisc *nd) {
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assert(!nd->recv_event_source);
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assert(!nd->timeout_event_source);
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r = sd_event_now(nd->event, clock_boottime_or_monotonic(), &time_now);
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if (r < 0)
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goto fail;
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nd->fd = icmp6_bind_router_solicitation(nd->ifindex);
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if (nd->fd < 0)
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return nd->fd;
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@ -359,6 +398,19 @@ _public_ int sd_ndisc_start(sd_ndisc *nd) {
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(void) sd_event_source_set_description(nd->timeout_event_source, "ndisc-timeout");
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r = sd_event_add_time(nd->event, &nd->timeout_no_ra,
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clock_boottime_or_monotonic(),
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time_now + NDISC_TIMEOUT_NO_RA_USEC,
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10 * USEC_PER_MSEC, ndisc_timeout_no_ra, nd);
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if (r < 0)
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goto fail;
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r = sd_event_source_set_priority(nd->timeout_no_ra, nd->event_priority);
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if (r < 0)
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goto fail;
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(void) sd_event_source_set_description(nd->timeout_no_ra, "ndisc-timeout-no-ra");
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log_ndisc("Started IPv6 Router Solicitation client");
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return 1;
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@ -27,6 +27,7 @@
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#include "icmp6-util.h"
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#include "socket-util.h"
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#include "strv.h"
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#include "ndisc-internal.h"
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static struct ether_addr mac_addr = {
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.ether_addr_octet = {'A', 'B', 'C', '1', '2', '3'}
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@ -35,6 +36,7 @@ static struct ether_addr mac_addr = {
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static bool verbose = false;
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static sd_event_source *test_hangcheck;
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static int test_fd[2];
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static sd_ndisc *test_timeout_nd;
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typedef int (*send_ra_t)(uint8_t flags);
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static send_ra_t send_ra_function;
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@ -237,6 +239,9 @@ static int send_ra(uint8_t flags) {
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}
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int icmp6_send_router_solicitation(int s, const struct ether_addr *ether_addr) {
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if (!send_ra_function)
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return 0;
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return send_ra_function(0);
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}
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@ -320,6 +325,100 @@ static void test_rs(void) {
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sd_event_unref(e);
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}
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static int test_timeout_value(uint8_t flags) {
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static int count = 0;
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static usec_t last = 0;
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sd_ndisc *nd = test_timeout_nd;
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usec_t min, max;
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char time_string_min[FORMAT_TIMESPAN_MAX];
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char time_string_nd[FORMAT_TIMESPAN_MAX];
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char time_string_max[FORMAT_TIMESPAN_MAX];
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assert_se(nd);
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assert_se(nd->event);
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if (++count >= 20)
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sd_event_exit(nd->event, 0);
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if (last == 0) {
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/* initial RT = IRT + RAND*IRT */
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min = NDISC_ROUTER_SOLICITATION_INTERVAL -
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NDISC_ROUTER_SOLICITATION_INTERVAL / 10;
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max = NDISC_ROUTER_SOLICITATION_INTERVAL +
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NDISC_ROUTER_SOLICITATION_INTERVAL / 10;
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} else {
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/* next RT = 2*RTprev + RAND*RTprev */
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min = 2 * last - last / 10;
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max = 2 * last + last / 10;
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}
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/* final RT > MRT */
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if (last * 2 > NDISC_MAX_ROUTER_SOLICITATION_INTERVAL) {
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min = NDISC_MAX_ROUTER_SOLICITATION_INTERVAL -
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NDISC_MAX_ROUTER_SOLICITATION_INTERVAL / 10;
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max = NDISC_MAX_ROUTER_SOLICITATION_INTERVAL +
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NDISC_MAX_ROUTER_SOLICITATION_INTERVAL / 10;
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}
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format_timespan(time_string_min, FORMAT_TIMESPAN_MAX,
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min, USEC_PER_MSEC);
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format_timespan(time_string_nd, FORMAT_TIMESPAN_MAX,
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nd->retransmit_time, USEC_PER_MSEC);
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format_timespan(time_string_max, FORMAT_TIMESPAN_MAX,
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max, USEC_PER_MSEC);
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log_info("backoff timeout interval %2d %s%s <= %s <= %s",
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count,
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(last * 2 > NDISC_MAX_ROUTER_SOLICITATION_INTERVAL)? "(max) ": "",
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time_string_min, time_string_nd, time_string_max);
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assert_se(min <= nd->retransmit_time);
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assert_se(max >= nd->retransmit_time);
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last = nd->retransmit_time;
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assert_se(sd_event_source_set_time(nd->timeout_event_source, 0) >= 0);
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return 0;
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}
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static void test_timeout(void) {
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sd_event *e;
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sd_ndisc *nd;
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usec_t time_now = now(clock_boottime_or_monotonic());
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if (verbose)
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printf("* %s\n", __FUNCTION__);
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send_ra_function = test_timeout_value;
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assert_se(sd_event_new(&e) >= 0);
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assert_se(sd_ndisc_new(&nd) >= 0);
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assert_se(nd);
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test_timeout_nd = nd;
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assert_se(sd_ndisc_attach_event(nd, e, 0) >= 0);
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assert_se(sd_ndisc_set_ifindex(nd, 42) >= 0);
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assert_se(sd_ndisc_set_mac(nd, &mac_addr) >= 0);
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assert_se(sd_event_add_time(e, &test_hangcheck, clock_boottime_or_monotonic(),
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time_now + 2U * USEC_PER_SEC, 0,
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test_rs_hangcheck, NULL) >= 0);
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assert_se(sd_ndisc_start(nd) >= 0);
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sd_event_loop(e);
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test_hangcheck = sd_event_source_unref(test_hangcheck);
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nd = sd_ndisc_unref(nd);
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sd_event_unref(e);
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}
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int main(int argc, char *argv[]) {
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log_set_max_level(LOG_DEBUG);
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@ -327,6 +426,7 @@ int main(int argc, char *argv[]) {
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log_open();
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test_rs();
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test_timeout();
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return 0;
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}
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