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Systemd/src/libsystemd-network/dhcp-network.c

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/***
This file is part of systemd.
Copyright (C) 2013 Intel Corporation. All rights reserved.
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include <errno.h>
#include <net/ethernet.h>
#include <net/if_arp.h>
#include <stdio.h>
#include <string.h>
#include <sys/socket.h>
#include <linux/filter.h>
#include <linux/if_infiniband.h>
#include <linux/if_packet.h>
#include "dhcp-internal.h"
#include "fd-util.h"
#include "socket-util.h"
static int _bind_raw_socket(int ifindex, union sockaddr_union *link,
uint32_t xid, const uint8_t *mac_addr,
size_t mac_addr_len,
const uint8_t *bcast_addr,
const struct ether_addr *eth_mac,
uint16_t arp_type, uint8_t dhcp_hlen) {
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 */
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_B + BPF_ABS, offsetof(DHCPPacket, ip.frag_off)), /* A <- Flags */
BPF_STMT(BPF_ALU + BPF_AND + BPF_K, 0x20), /* A <- A & 0x20 (More Fragments bit) */
BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0, 1, 0), /* A == 0 ? */
BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(DHCPPacket, ip.frag_off)), /* A <- Flags + Fragment offset */
BPF_STMT(BPF_ALU + BPF_AND + BPF_K, 0x1fff), /* A <- A & 0x1fff (Fragment offset) */
BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0, 1, 0), /* A == 0 ? */
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, arp_type, 1, 0), /* header type == arp_type ? */
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, dhcp_hlen, 1, 0), /* address length == dhcp_hlen ? */
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 */
BPF_STMT(BPF_LD + BPF_IMM, htobe32(*((unsigned int *) eth_mac))), /* A <- 4 bytes of client's MAC */
BPF_STMT(BPF_MISC + BPF_TAX, 0), /* X <- A */
BPF_STMT(BPF_LD + BPF_W + BPF_ABS, offsetof(DHCPPacket, dhcp.chaddr)), /* A <- 4 bytes of MAC from dhcp.chaddr */
BPF_STMT(BPF_ALU + BPF_XOR + BPF_X, 0), /* A xor X */
BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0, 1, 0), /* A == 0 ? */
BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
BPF_STMT(BPF_LD + BPF_IMM, htobe16(*((unsigned short *) (((char *) eth_mac) + 4)))), /* A <- remainder of client's MAC */
BPF_STMT(BPF_MISC + BPF_TAX, 0), /* X <- A */
BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(DHCPPacket, dhcp.chaddr) + 4), /* A <- remainder of MAC from dhcp.chaddr */
BPF_STMT(BPF_ALU + BPF_XOR + BPF_X, 0), /* A xor X */
BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0, 1, 0), /* A == 0 ? */
BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
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 = {
.len = ELEMENTSOF(filter),
.filter = filter
};
_cleanup_close_ int s = -1;
int r, on = 1;
assert(ifindex > 0);
assert(link);
s = socket(AF_PACKET, SOCK_DGRAM | SOCK_CLOEXEC | SOCK_NONBLOCK, 0);
if (s < 0)
return -errno;
r = setsockopt(s, SOL_PACKET, PACKET_AUXDATA, &on, sizeof(on));
if (r < 0)
return -errno;
r = setsockopt(s, SOL_SOCKET, SO_ATTACH_FILTER, &fprog, sizeof(fprog));
if (r < 0)
return -errno;
link->ll.sll_family = AF_PACKET;
link->ll.sll_protocol = htobe16(ETH_P_IP);
link->ll.sll_ifindex = ifindex;
link->ll.sll_hatype = htobe16(arp_type);
link->ll.sll_halen = mac_addr_len;
memcpy(link->ll.sll_addr, bcast_addr, mac_addr_len);
r = bind(s, &link->sa, sizeof(link->ll));
if (r < 0)
return -errno;
r = s;
s = -1;
return r;
}
int dhcp_network_bind_raw_socket(int ifindex, union sockaddr_union *link,
uint32_t xid, const uint8_t *mac_addr,
size_t mac_addr_len, uint16_t arp_type) {
static const uint8_t eth_bcast[] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
/* Default broadcast address for IPoIB */
static const uint8_t ib_bcast[] = {
0x00, 0xff, 0xff, 0xff, 0xff, 0x12, 0x40, 0x1b,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0xff, 0xff, 0xff, 0xff
};
struct ether_addr eth_mac = { { 0, 0, 0, 0, 0, 0 } };
const uint8_t *bcast_addr = NULL;
uint8_t dhcp_hlen = 0;
assert_return(mac_addr_len > 0, -EINVAL);
if (arp_type == ARPHRD_ETHER) {
assert_return(mac_addr_len == ETH_ALEN, -EINVAL);
memcpy(&eth_mac, mac_addr, ETH_ALEN);
bcast_addr = eth_bcast;
dhcp_hlen = ETH_ALEN;
} else if (arp_type == ARPHRD_INFINIBAND) {
assert_return(mac_addr_len == INFINIBAND_ALEN, -EINVAL);
bcast_addr = ib_bcast;
} else
return -EINVAL;
return _bind_raw_socket(ifindex, link, xid, mac_addr, mac_addr_len,
bcast_addr, &eth_mac, arp_type, dhcp_hlen);
}
int dhcp_network_bind_udp_socket(be32_t address, uint16_t port) {
union sockaddr_union src = {
.in.sin_family = AF_INET,
.in.sin_port = htobe16(port),
.in.sin_addr.s_addr = address,
};
_cleanup_close_ int s = -1;
int r, on = 1, tos = IPTOS_CLASS_CS6;
s = socket(AF_INET, SOCK_DGRAM | SOCK_CLOEXEC | SOCK_NONBLOCK, 0);
if (s < 0)
return -errno;
r = setsockopt(s, IPPROTO_IP, IP_TOS, &tos, sizeof(tos));
if (r < 0)
return -errno;
r = setsockopt(s, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));
if (r < 0)
return -errno;
if (address == INADDR_ANY) {
r = setsockopt(s, IPPROTO_IP, IP_PKTINFO, &on, sizeof(on));
if (r < 0)
return -errno;
r = setsockopt(s, SOL_SOCKET, SO_BROADCAST, &on, sizeof(on));
if (r < 0)
return -errno;
} else {
r = setsockopt(s, IPPROTO_IP, IP_FREEBIND, &on, sizeof(on));
if (r < 0)
return -errno;
}
r = bind(s, &src.sa, sizeof(src.in));
if (r < 0)
return -errno;
r = s;
s = -1;
return r;
}
int dhcp_network_send_raw_socket(int s, const union sockaddr_union *link,
const void *packet, size_t len) {
int r;
assert(link);
assert(packet);
assert(len);
r = sendto(s, packet, len, 0, &link->sa, sizeof(link->ll));
if (r < 0)
return -errno;
return 0;
}
int dhcp_network_send_udp_socket(int s, be32_t address, uint16_t port,
const void *packet, size_t len) {
union sockaddr_union dest = {
.in.sin_family = AF_INET,
.in.sin_port = htobe16(port),
.in.sin_addr.s_addr = address,
};
int r;
assert(s >= 0);
assert(packet);
assert(len);
r = sendto(s, packet, len, 0, &dest.sa, sizeof(dest.in));
if (r < 0)
return -errno;
return 0;
}
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