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sd-dhcp: be more detailed about invalid headers

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This may be a common problem, so let's make it simpler to debug,
at least for now.
This commit is contained in:
Tom Gundersen 2014-02-23 01:34:05 +01:00
parent d8148cc59d
commit ac4f16ab4d
2 changed files with 28 additions and 10 deletions
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34
src/libsystemd-dhcp/dhcp-packet.c
View file

@ -132,38 +132,58 @@ int dhcp_packet_verify_headers(DHCPPacket *packet, uint8_t op, size_t len) {
assert(op == BOOTREQUEST || op == BOOTREPLY);
if (len < (DHCP_IP_UDP_SIZE + DHCP_MESSAGE_SIZE))
if (len < (DHCP_IP_UDP_SIZE + DHCP_MESSAGE_SIZE)) {
log_dhcp_client(client, "ignoring packet: packet too small");
return -EINVAL;
}
hdrlen = packet->ip.ihl * 4;
if (hdrlen < 20 || hdrlen > len || dhcp_checksum(&packet->ip, hdrlen))
if (hdrlen < 20 || hdrlen > len) {
log_dhcp_client(client, "ignoring packet: header with wrong size");
return -EINVAL;
}
if (hdrlen + be16toh(packet->udp.len) > len)
if (dhcp_checksum(&packet->ip, hdrlen)) {
log_dhcp_client(client, "ignoring packet: invalid ip checksum");
return -EINVAL;
}
if (hdrlen + be16toh(packet->udp.len) > len) {
log_dhcp_client(client, "ignoring packet: packet too small (udp.len=%u)",
be16toh(packet->udp.len));
return -EINVAL;
}
if (packet->udp.check) {
packet->ip.check = packet->udp.len;
packet->ip.ttl = 0;
if (dhcp_checksum(&packet->ip.ttl,
be16toh(packet->udp.len) + 12))
be16toh(packet->udp.len) + 12)) {
log_dhcp_client(client, "ignoring packet: invalid udp checksum");
return -EINVAL;
}
}
if (packet->dhcp.op != op)
if (packet->dhcp.op != op) {
log_dhcp_client(client, "ignoring packet: wrong operation");
return -EINVAL;
}
switch (op) {
case BOOTREQUEST:
if (be16toh(packet->udp.source) != DHCP_PORT_CLIENT ||
be16toh(packet->udp.dest) != DHCP_PORT_SERVER)
be16toh(packet->udp.dest) != DHCP_PORT_SERVER) {
log_dhcp_client(client, "ignoring packet: wrong ports");
return -EINVAL;
}
break;
case BOOTREPLY:
if (be16toh(packet->udp.source) != DHCP_PORT_SERVER ||
be16toh(packet->udp.dest) != DHCP_PORT_CLIENT)
be16toh(packet->udp.dest) != DHCP_PORT_CLIENT) {
log_dhcp_client(client, "ignoring packet: wrong ports");
return -EINVAL;
}
break;
}

4
src/libsystemd-dhcp/sd-dhcp-client.c
View file

@ -870,10 +870,8 @@ static int client_receive_message_raw(sd_event_source *s, int fd,
packet = (DHCPPacket *) buf;
r = dhcp_packet_verify_headers(packet, BOOTREPLY, len);
if (r < 0) {
log_dhcp_client(client, "ignoring DHCP packet with invalid headers");
if (r < 0)
return 0;
}
len -= DHCP_IP_UDP_SIZE;