From 7429b07f822348dc5a87208ce107f5f6bf02656d Mon Sep 17 00:00:00 2001 From: Tom Gundersen Date: Sun, 6 Apr 2014 19:23:33 +0200 Subject: [PATCH 1/1] 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. --- src/libsystemd-network/dhcp-internal.h | 2 +- src/libsystemd-network/dhcp-network.c | 21 +++++++++++++++++++-- src/libsystemd-network/sd-dhcp-client.c | 4 ++-- src/libsystemd-network/test-dhcp-client.c | 2 +- 4 files changed, 23 insertions(+), 6 deletions(-) diff --git a/src/libsystemd-network/dhcp-internal.h b/src/libsystemd-network/dhcp-internal.h index 064b13b59..324c2a8d7 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 a9a15b4d5..902c9d9be 100644 --- a/src/libsystemd-network/dhcp-network.c +++ b/src/libsystemd-network/dhcp-network.c @@ -23,6 +23,7 @@ #include #include #include +#include #include #include #include @@ -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 722f86283..da41c478e 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 2d4d59096..4420436f8 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; -- 2.30.2