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sd-dhcp-client: Add reference counting for DHCP

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The DHCP library user can decide to free the DHCP client any time
the callback is called. After the callback has been called, other
computations may still be needed - the best example being a full
restart of the DHCP procedure in case of lease expiry.

Fix this by introducing proper reference counting. Properly handle
a returned NULL from the notify and stop functions if the DHCP
client was freed.
This commit is contained in:
Patrik Flykt
2014-04-11 10:53:10 +03:00
parent 48a4612e6b
commit e5b04c8de8
4 changed files with 73 additions and 33 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/libsystemd-network/sd-dhcp-client.c
+66 -29
View File
@@ -28,6 +28,7 @@
#include "util.h"
#include "list.h"
#include "refcnt.h"
#include "dhcp-protocol.h"
#include "dhcp-internal.h"
@@ -35,6 +36,8 @@
#include "sd-dhcp-client.h"
struct sd_dhcp_client {
RefCount n_ref;
DHCPState state;
sd_event *event;
int event_priority;
@@ -77,6 +80,7 @@ static int client_receive_message_raw(sd_event_source *s, int fd,
uint32_t revents, void *userdata);
static int client_receive_message_udp(sd_event_source *s, int fd,
uint32_t revents, void *userdata);
static sd_dhcp_client *client_stop(sd_dhcp_client *client, int error);
int sd_dhcp_client_set_callback(sd_dhcp_client *client, sd_dhcp_client_cb_t cb,
void *userdata) {
@@ -155,10 +159,13 @@ int sd_dhcp_client_set_mac(sd_dhcp_client *client,
if (client->state != DHCP_STATE_INIT) {
log_dhcp_client(client, "Changing MAC address on running DHCP "
"client, restarting");
sd_dhcp_client_stop(client);
need_restart = true;
client = client_stop(client, DHCP_EVENT_STOP);
}
if (!client)
return 0;
memcpy(&client->client_id.mac_addr, addr, ETH_ALEN);
client->client_id.type = 0x01;
@@ -182,11 +189,14 @@ int sd_dhcp_client_get_lease(sd_dhcp_client *client, sd_dhcp_lease **ret) {
return 0;
}
static int client_notify(sd_dhcp_client *client, int event) {
if (client->cb)
static sd_dhcp_client *client_notify(sd_dhcp_client *client, int event) {
if (client->cb) {
client = sd_dhcp_client_ref(client);
client->cb(client, event, client->userdata);
client = sd_dhcp_client_unref(client);
}
return 0;
return client;
}
static int client_initialize(sd_dhcp_client *client) {
@@ -214,16 +224,17 @@ static int client_initialize(sd_dhcp_client *client) {
return 0;
}
static int client_stop(sd_dhcp_client *client, int error) {
assert_return(client, -EINVAL);
static sd_dhcp_client *client_stop(sd_dhcp_client *client, int error) {
assert_return(client, NULL);
client_notify(client, error);
log_dhcp_client(client, "STOPPED %d", error);
client_initialize(client);
client = client_notify(client, error);
log_dhcp_client(client, "STOPPED");
if (client)
client_initialize(client);
return 0;
return client;
}
static int client_message_init(sd_dhcp_client *client, DHCPMessage *message,
@@ -617,11 +628,13 @@ static int client_timeout_expire(sd_event_source *s, uint64_t usec,
log_dhcp_client(client, "EXPIRED");
client_notify(client, DHCP_EVENT_EXPIRED);
client = client_notify(client, DHCP_EVENT_EXPIRED);
/* start over as the lease was lost */
client_initialize(client);
client_start(client);
/* lease was lost, start over if not freed */
if (client) {
client_initialize(client);
client_start(client);
}
return 0;
}
@@ -1031,8 +1044,11 @@ static int client_handle_message(sd_dhcp_client *client, DHCPMessage *message,
if (r < 0)
goto error;
if (notify_event)
client_notify(client, notify_event);
if (notify_event) {
client = client_notify(client, notify_event);
if (!client)
return 0;
}
client->receive_message =
sd_event_source_unref(client->receive_message);
@@ -1052,9 +1068,9 @@ static int client_handle_message(sd_dhcp_client *client, DHCPMessage *message,
error:
if (r < 0 || r == DHCP_EVENT_NO_LEASE)
return client_stop(client, r);
client_stop(client, r);
return 0;
return r;
}
static int client_receive_message_udp(sd_event_source *s, int fd,
@@ -1159,7 +1175,11 @@ int sd_dhcp_client_start(sd_dhcp_client *client) {
}
int sd_dhcp_client_stop(sd_dhcp_client *client) {
return client_stop(client, DHCP_EVENT_STOP);
assert_return(client, -EINVAL);
client_stop(client, DHCP_EVENT_STOP);
return 0;
}
int sd_dhcp_client_attach_event(sd_dhcp_client *client, sd_event *event,
@@ -1197,19 +1217,35 @@ sd_event *sd_dhcp_client_get_event(sd_dhcp_client *client) {
return client->event;
}
void sd_dhcp_client_free(sd_dhcp_client *client) {
if (!client)
return;
sd_dhcp_client *sd_dhcp_client_ref(sd_dhcp_client *client) {
if (client)
assert_se(REFCNT_INC(client->n_ref) >= 2);
sd_dhcp_client_stop(client);
sd_dhcp_client_detach_event(client);
free(client->req_opts);
free(client);
return client;
}
DEFINE_TRIVIAL_CLEANUP_FUNC(sd_dhcp_client*, sd_dhcp_client_free);
#define _cleanup_dhcp_client_free_ _cleanup_(sd_dhcp_client_freep)
sd_dhcp_client *sd_dhcp_client_unref(sd_dhcp_client *client) {
if (client && REFCNT_DEC(client->n_ref) <= 0) {
log_dhcp_client(client, "UNREF");
client_initialize(client);
client->receive_message =
sd_event_source_unref(client->receive_message);
sd_dhcp_client_detach_event(client);
free(client->req_opts);
free(client);
return NULL;
}
return client;
}
DEFINE_TRIVIAL_CLEANUP_FUNC(sd_dhcp_client*, sd_dhcp_client_unref);
#define _cleanup_dhcp_client_free_ _cleanup_(sd_dhcp_client_unrefp)
int sd_dhcp_client_new(sd_dhcp_client **ret) {
_cleanup_dhcp_client_free_ sd_dhcp_client *client = NULL;
@@ -1220,6 +1256,7 @@ int sd_dhcp_client_new(sd_dhcp_client **ret) {
if (!client)
return -ENOMEM;
client->n_ref = REFCNT_INIT;
client->state = DHCP_STATE_INIT;
client->index = -1;
client->fd = -1;
src/libsystemd-network/test-dhcp-client.c
+2 -2
View File
@@ -251,7 +251,7 @@ static void test_discover_message(sd_event *e)
sd_event_run(e, (uint64_t) -1);
sd_dhcp_client_stop(client);
sd_dhcp_client_free(client);
sd_dhcp_client_unref(client);
test_fd[1] = safe_close(test_fd[1]);
@@ -476,7 +476,7 @@ static void test_addr_acq(sd_event *e) {
sd_dhcp_client_set_callback(client, NULL, NULL);
sd_dhcp_client_stop(client);
sd_dhcp_client_free(client);
sd_dhcp_client_unref(client);
test_fd[1] = safe_close(test_fd[1]);
src/network/networkd-link.c
+1 -1
View File
@@ -80,7 +80,7 @@ void link_free(Link *link) {
assert(link->manager);
sd_dhcp_client_free(link->dhcp_client);
sd_dhcp_client_unref(link->dhcp_client);
sd_dhcp_lease_unref(link->dhcp_lease);
sd_ipv4ll_free(link->ipv4ll);
src/systemd/sd-dhcp-client.h
+4 -1
View File
@@ -54,7 +54,10 @@ int sd_dhcp_client_get_lease(sd_dhcp_client *client, sd_dhcp_lease **ret);
int sd_dhcp_client_stop(sd_dhcp_client *client);
int sd_dhcp_client_start(sd_dhcp_client *client);
void sd_dhcp_client_free(sd_dhcp_client *client);
sd_dhcp_client *sd_dhcp_client_ref(sd_dhcp_client *client);
sd_dhcp_client *sd_dhcp_client_unref(sd_dhcp_client *client);
int sd_dhcp_client_new(sd_dhcp_client **ret);
int sd_dhcp_client_attach_event(sd_dhcp_client *client, sd_event *event, int priority);