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sd-dhcp6-client: Add DHCPv6 client Solicitation timeout handling

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Add the core of DHCPv6 client message retransmission and upper bound
timer and message count handling according to RFC 3315 Secions 7.1.2
and 14. Omit the DHCPv6 initial delay; for now it is assumed that
systemd-networkd will provide decent startup randomization that will
desynchronize the clients.

When reinitializing the client, clear all timers.
This commit is contained in:
Patrik Flykt 2014-06-19 15:39:15 +03:00
parent 813e3a6ffc
commit d1b0afe365
3 changed files with 142 additions and 0 deletions
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5
src/libsystemd-network/dhcp6-protocol.h
View File

@ -41,6 +41,10 @@ enum {
DHCP6_PORT_CLIENT = 546,
};
#define DHCP6_SOL_MAX_DELAY 1 * USEC_PER_SEC
#define DHCP6_SOL_TIMEOUT 1 * USEC_PER_SEC
#define DHCP6_SOL_MAX_RT 120 * USEC_PER_SEC
enum {
DHCP6_DUID_LLT = 1,
DHCP6_DUID_EN = 2,
@ -51,6 +55,7 @@ enum {
enum DHCP6State {
DHCP6_STATE_STOPPED = 0,
DHCP6_STATE_RS = 1,
DHCP6_STATE_SOLICITATION = 2,
};
enum {

135
src/libsystemd-network/sd-dhcp6-client.c
View File

@ -46,6 +46,10 @@ struct sd_dhcp6_client {
int index;
struct ether_addr mac_addr;
DHCP6IA ia_na;
usec_t retransmit_time;
uint8_t retransmit_count;
sd_event_source *timeout_resend;
sd_event_source *timeout_resend_expire;
sd_dhcp6_client_cb_t cb;
void *userdata;
@ -109,6 +113,12 @@ static int client_initialize(sd_dhcp6_client *client)
client->ia_na.timeout_t2 =
sd_event_source_unref(client->ia_na.timeout_t2);
client->retransmit_time = 0;
client->retransmit_count = 0;
client->timeout_resend = sd_event_source_unref(client->timeout_resend);
client->timeout_resend_expire =
sd_event_source_unref(client->timeout_resend_expire);
client->state = DHCP6_STATE_STOPPED;
return 0;
@ -124,6 +134,118 @@ static sd_dhcp6_client *client_stop(sd_dhcp6_client *client, int error) {
return client;
}
static int client_timeout_resend_expire(sd_event_source *s, uint64_t usec,
void *userdata) {
sd_dhcp6_client *client = userdata;
assert(s);
assert(client);
assert(client->event);
client_stop(client, DHCP6_EVENT_RESEND_EXPIRE);
return 0;
}
static usec_t client_timeout_compute_random(usec_t val) {
return val - val / 10 +
(random_u32() % (2 * USEC_PER_SEC)) * val / 10 / USEC_PER_SEC;
}
static int client_timeout_resend(sd_event_source *s, uint64_t usec,
void *userdata) {
int r = 0;
sd_dhcp6_client *client = userdata;
usec_t time_now, init_retransmit_time, max_retransmit_time;
usec_t max_retransmit_duration;
uint8_t max_retransmit_count;
char time_string[FORMAT_TIMESPAN_MAX];
assert(s);
assert(client);
assert(client->event);
client->timeout_resend = sd_event_source_unref(client->timeout_resend);
switch (client->state) {
case DHCP6_STATE_SOLICITATION:
init_retransmit_time = DHCP6_SOL_TIMEOUT;
max_retransmit_time = DHCP6_SOL_MAX_RT;
max_retransmit_count = 0;
max_retransmit_duration = 0;
break;
case DHCP6_STATE_STOPPED:
case DHCP6_STATE_RS:
return 0;
}
if (max_retransmit_count &&
client->retransmit_count >= max_retransmit_count) {
client_stop(client, DHCP6_EVENT_RETRANS_MAX);
return 0;
}
r = sd_event_now(client->event, CLOCK_MONOTONIC, &time_now);
if (r < 0)
goto error;
if (!client->retransmit_time) {
client->retransmit_time =
client_timeout_compute_random(init_retransmit_time);
} else {
if (max_retransmit_time &&
client->retransmit_time > max_retransmit_time / 2)
client->retransmit_time = client_timeout_compute_random(max_retransmit_time);
else
client->retransmit_time += client_timeout_compute_random(client->retransmit_time);
}
log_dhcp6_client(client, "Next retransmission in %s",
format_timespan(time_string, FORMAT_TIMESPAN_MAX,
client->retransmit_time, 0));
r = sd_event_add_time(client->event, &client->timeout_resend,
CLOCK_MONOTONIC,
time_now + client->retransmit_time,
10 * USEC_PER_MSEC, client_timeout_resend,
client);
if (r < 0)
goto error;
r = sd_event_source_set_priority(client->timeout_resend,
client->event_priority);
if (r < 0)
goto error;
if (max_retransmit_duration && !client->timeout_resend_expire) {
log_dhcp6_client(client, "Max retransmission duration %"PRIu64" secs",
max_retransmit_duration / USEC_PER_SEC);
r = sd_event_add_time(client->event,
&client->timeout_resend_expire,
CLOCK_MONOTONIC,
time_now + max_retransmit_duration,
USEC_PER_SEC,
client_timeout_resend_expire, client);
if (r < 0)
goto error;
r = sd_event_source_set_priority(client->timeout_resend_expire,
client->event_priority);
if (r < 0)
goto error;
}
error:
if (r < 0)
client_stop(client, r);
return 0;
}
static int client_ensure_iaid(sd_dhcp6_client *client) {
const char *name = NULL;
uint64_t id;
@ -180,6 +302,19 @@ static int client_start(sd_dhcp6_client *client)
if (r < 0)
return r;
client->state = DHCP6_STATE_SOLICITATION;
r = sd_event_add_time(client->event, &client->timeout_resend,
CLOCK_MONOTONIC, 0, 0, client_timeout_resend,
client);
if (r < 0)
return r;
r = sd_event_source_set_priority(client->timeout_resend,
client->event_priority);
if (r < 0)
return r;
return 0;
}

2
src/systemd/sd-dhcp6-client.h
View File

@ -28,6 +28,8 @@
enum {
DHCP6_EVENT_STOP = 0,
DHCP6_EVENT_RESEND_EXPIRE = 10,
DHCP6_EVENT_RETRANS_MAX = 11,
};
typedef struct sd_dhcp6_client sd_dhcp6_client;