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authorTom Gundersen <teg@jklm.no>2014-04-06 19:23:33 +0200
committerTom Gundersen <teg@jklm.no>2014-04-06 19:42:11 +0200
commit7429b07f822348dc5a87208ce107f5f6bf02656d (patch)
treece9b61db02a34ba440dcc35385b9151e37754fee /src/libsystemd-network
parent0c79c68d93d721d37ba088fb50dbf07bb0d447e5 (diff)
sd-dhcp-client: improve BPF
Try a bit harder to make the kernel drop packets not for us. This should reduce the number of wakeups from n^2 to n in the number of dhcp clients, which admittedly only makes a differenc in very extreme cases.
Diffstat (limited to 'src/libsystemd-network')
-rw-r--r--src/libsystemd-network/dhcp-internal.h2
-rw-r--r--src/libsystemd-network/dhcp-network.c21
-rw-r--r--src/libsystemd-network/sd-dhcp-client.c4
-rw-r--r--src/libsystemd-network/test-dhcp-client.c2
4 files changed, 23 insertions, 6 deletions
diff --git a/src/libsystemd-network/dhcp-internal.h b/src/libsystemd-network/dhcp-internal.h
index 064b13b59f..324c2a8d7a 100644
--- a/src/libsystemd-network/dhcp-internal.h
+++ b/src/libsystemd-network/dhcp-internal.h
@@ -29,7 +29,7 @@
#include "dhcp-protocol.h"
-int dhcp_network_bind_raw_socket(int index, union sockaddr_union *link);
+int dhcp_network_bind_raw_socket(int index, union sockaddr_union *link, uint32_t xid);
int dhcp_network_bind_udp_socket(int index, be32_t address, uint16_t port);
int dhcp_network_send_raw_socket(int s, const union sockaddr_union *link,
const void *packet, size_t len);
diff --git a/src/libsystemd-network/dhcp-network.c b/src/libsystemd-network/dhcp-network.c
index a9a15b4d5a..902c9d9be2 100644
--- a/src/libsystemd-network/dhcp-network.c
+++ b/src/libsystemd-network/dhcp-network.c
@@ -23,6 +23,7 @@
#include <string.h>
#include <linux/if_packet.h>
#include <net/ethernet.h>
+#include <net/if_arp.h>
#include <stdio.h>
#include <unistd.h>
#include <linux/filter.h>
@@ -31,18 +32,34 @@
#include "dhcp-internal.h"
-int dhcp_network_bind_raw_socket(int index, union sockaddr_union *link)
-{
+int dhcp_network_bind_raw_socket(int index, union sockaddr_union *link, uint32_t xid) {
struct sock_filter filter[] = {
BPF_STMT(BPF_LD + BPF_W + BPF_LEN, 0), /* A <- packet length */
BPF_JUMP(BPF_JMP + BPF_JGE + BPF_K, sizeof(DHCPPacket), 1, 0), /* packet >= DHCPPacket ? */
BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
+ /* TODO: match ip.version */
BPF_STMT(BPF_LD + BPF_B + BPF_ABS, offsetof(DHCPPacket, ip.protocol)), /* A <- IP protocol */
BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, IPPROTO_UDP, 1, 0), /* IP protocol == UDP ? */
BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(DHCPPacket, udp.dest)), /* A <- UDP destination port */
BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, DHCP_PORT_CLIENT, 1, 0), /* UDP destination port == DHCP client port ? */
BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
+ BPF_STMT(BPF_LD + BPF_B + BPF_ABS, offsetof(DHCPPacket, dhcp.op)), /* A <- DHCP op */
+ BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, BOOTREPLY, 1, 0), /* op == BOOTREPLY ? */
+ BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
+ BPF_STMT(BPF_LD + BPF_B + BPF_ABS, offsetof(DHCPPacket, dhcp.htype)), /* A <- DHCP header type */
+ BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ARPHRD_ETHER, 1, 0), /* header type == ARPHRD_ETHER ? */
+ BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
+ BPF_STMT(BPF_LD + BPF_B + BPF_ABS, offsetof(DHCPPacket, dhcp.hlen)), /* A <- mac address length */
+ BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ETHER_ADDR_LEN, 1, 0), /* address length == ETHER_ADDR_LEN ? */
+ BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
+ BPF_STMT(BPF_LD + BPF_W + BPF_ABS, offsetof(DHCPPacket, dhcp.xid)), /* A <- client identifier */
+ BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, xid, 1, 0), /* client identifier == xid ? */
+ BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
+ /* TODO: match chaddr */
+ BPF_STMT(BPF_LD + BPF_W + BPF_ABS, offsetof(DHCPPacket, dhcp.magic)), /* A <- DHCP magic cookie */
+ BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, DHCP_MAGIC_COOKIE, 1, 0), /* cookie == DHCP magic cookie ? */
+ BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
BPF_STMT(BPF_RET + BPF_K, 65535), /* return all */
};
struct sock_fprog fprog = {
diff --git a/src/libsystemd-network/sd-dhcp-client.c b/src/libsystemd-network/sd-dhcp-client.c
index 722f862832..da41c478ea 100644
--- a/src/libsystemd-network/sd-dhcp-client.c
+++ b/src/libsystemd-network/sd-dhcp-client.c
@@ -593,7 +593,7 @@ static int client_start(sd_dhcp_client *client) {
client->xid = random_u32();
- r = dhcp_network_bind_raw_socket(client->index, &client->link);
+ r = dhcp_network_bind_raw_socket(client->index, &client->link, client->xid);
if (r < 0) {
client_stop(client, r);
@@ -636,7 +636,7 @@ static int client_timeout_t2(sd_event_source *s, uint64_t usec, void *userdata)
client->state = DHCP_STATE_REBINDING;
client->attempt = 1;
- r = dhcp_network_bind_raw_socket(client->index, &client->link);
+ r = dhcp_network_bind_raw_socket(client->index, &client->link, client->xid);
if (r < 0) {
client_stop(client, r);
return 0;
diff --git a/src/libsystemd-network/test-dhcp-client.c b/src/libsystemd-network/test-dhcp-client.c
index 2d4d59096a..4420436f8a 100644
--- a/src/libsystemd-network/test-dhcp-client.c
+++ b/src/libsystemd-network/test-dhcp-client.c
@@ -190,7 +190,7 @@ int dhcp_network_send_raw_socket(int s, const union sockaddr_union *link,
return 575;
}
-int dhcp_network_bind_raw_socket(int index, union sockaddr_union *link)
+int dhcp_network_bind_raw_socket(int index, union sockaddr_union *link, uint32_t id)
{
if (socketpair(AF_UNIX, SOCK_STREAM, 0, test_fd) < 0)
return -errno;