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sd-dhcp-client: move magic cookie into DHCPMessage struct

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Also move the checking of it to the main message handler, rather than the
options parser.

Fix a bug, so we now drop the packet if any of the magic bytes don't match.
Before we used to only drop the packet if they were all wrong.
This commit is contained in:
Tom Gundersen 2014-04-06 14:05:32 +02:00
parent 19aa72f74e
commit 3b7ca119fd
4 changed files with 20 additions and 21 deletions
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10
src/libsystemd-network/dhcp-option.c
View File

@ -149,16 +149,12 @@ int dhcp_option_parse(DHCPMessage *message, size_t len,
if (!message)
return -EINVAL;
if (len < sizeof(DHCPMessage) + 4)
if (len < sizeof(DHCPMessage))
return -EINVAL;
len -= sizeof(DHCPMessage) + 4;
len -= sizeof(DHCPMessage);
if (opt[0] != 0x63 && opt[1] != 0x82 && opt[2] != 0x53 &&
opt[3] != 0x63)
return -EINVAL;
res = parse_options(&opt[4], len, &overload, &message_type,
res = parse_options(opt, len, &overload, &message_type,
cb, user_data);
if (res < 0)
return res;

14
src/libsystemd-network/dhcp-packet.c
View File

@ -43,23 +43,13 @@ int dhcp_message_init(DHCPMessage *message, uint8_t op, uint32_t xid,
assert(op == BOOTREQUEST || op == BOOTREPLY);
*opt = (uint8_t *)(message + 1);
if (*optlen < 4)
return -ENOBUFS;
*optlen -= 4;
message->op = op;
message->htype = ARPHRD_ETHER;
message->hlen = ETHER_ADDR_LEN;
message->xid = htobe32(xid);
message->magic = htobe32(DHCP_MAGIC_COOKIE);
(*opt)[0] = 0x63;
(*opt)[1] = 0x82;
(*opt)[2] = 0x53;
(*opt)[3] = 0x63;
*opt += 4;
*opt = (uint8_t *)(message + 1);
err = dhcp_option_append(opt, optlen, DHCP_OPTION_MESSAGE_TYPE, 1,
&type);

4
src/libsystemd-network/dhcp-protocol.h
View File

@ -43,6 +43,7 @@ struct DHCPMessage {
uint8_t chaddr[16];
uint8_t sname[64];
uint8_t file[128];
be32_t magic;
} _packed_;
typedef struct DHCPMessage DHCPMessage;
@ -58,7 +59,8 @@ typedef struct DHCPPacket DHCPPacket;
#define DHCP_IP_SIZE (int32_t)(sizeof(struct iphdr))
#define DHCP_IP_UDP_SIZE (int32_t)(sizeof(struct udphdr) + DHCP_IP_SIZE)
#define DHCP_MESSAGE_SIZE (int32_t)(sizeof(DHCPMessage))
#define DHCP_MIN_OPTIONS_SIZE 312
#define DHCP_MIN_OPTIONS_SIZE 308
#define DHCP_MAGIC_COOKIE (uint32_t)(0x63825363)
enum {
DHCP_PORT_SERVER = 67,

11
src/libsystemd-network/sd-dhcp-client.c
View File

@ -22,6 +22,7 @@
#include <string.h>
#include <stdio.h>
#include <net/ethernet.h>
#include <net/if_arp.h>
#include <sys/param.h>
#include <sys/ioctl.h>
@ -936,6 +937,11 @@ static int client_handle_message(sd_dhcp_client *client, DHCPMessage *message,
return 0;
}
if (be32toh(message->magic) != DHCP_MAGIC_COOKIE) {
log_dhcp_client(client, "not a DHCP message: ignoring");
return 0;
}
if (message->op != BOOTREPLY) {
log_dhcp_client(client, "not a BOOTREPLY message: ignoring");
return 0;
@ -948,6 +954,11 @@ static int client_handle_message(sd_dhcp_client *client, DHCPMessage *message,
return 0;
}
if (message->htype != ARPHRD_ETHER || message->hlen != ETHER_ADDR_LEN) {
log_dhcp_client(client, "not an ethernet packet");
return 0;
}
if (memcmp(&message->chaddr[0], &client->client_id.mac_addr,
ETH_ALEN)) {
log_dhcp_client(client, "received chaddr does not match "