Nicholas J. Kain
27c9e2c553
Improve fingerprinting to support DHCP relay agents.
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Mostly reverts the previous commit and instead teaches ndhc to properly
handle the case when it is communicating with a DHCP relay agent on
its local segment rather than directly with a DHCP server.
2015-02-12 23:28:54 -05:00
Nicholas J. Kain
9f87bd8b30
udp_checksum(): Clamp the value of the UDP packet header length.
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Without this change, it is possible for malicious UDP packets to
make the function read past the end of a buffer.
If this was ever a possibility in ndhc, the previous commit fixed
that issue, but there is no reason for udp_checksum() to have
such a subtle precondition to proper use. This change also makes
it easier to audit correctness.
2015-01-06 07:07:08 -05:00
Nicholas J. Kain
6548b5ce54
get_raw_packet(): Perform the UDP checksum after the packet length
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checks.
This change makes it easier to verify that there can be no reads
beyond a buffer end by udp_checksum().
2015-01-06 04:32:58 -05:00
Nicholas J. Kain
c8dcf5a06b
Make sure that received DHCP packets have a valid options end marker.
2015-01-06 04:02:52 -05:00
Nicholas J. Kain
12114c9bae
Add more explicit length checks for get_raw_packet.
2014-07-25 20:34:01 -04:00
Nicholas J. Kain
ae03b6dd8f
Move the ip checksum code out to ncmlib.
2014-06-08 20:34:34 -04:00
Nicholas J. Kain
07cbd88049
Just use raw sockets for listening to DHCP requests. A UDP SO_BROADCAST
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socket was previously used only for receiving RENEWING packets, and it
added needless complexity and was somewhat fragile.
2014-04-16 01:00:36 -04:00
Nicholas J. Kain
ca85a6ba9f
Style cleanups in dhcp.c.
2014-04-16 00:24:40 -04:00
Nicholas J. Kain
baa394af9a
UDP listen sockets should be requested with 'U' instead of 'u'.
2014-04-15 20:54:35 -04:00
Nicholas J. Kain
18604c5245
get_udp_unicast_socket() needs to have the client address as an argument
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when sending the request to sockd.
Also, print error messages if sockd returns an invalid fd (< 0).
2014-04-15 17:55:28 -04:00
Nicholas J. Kain
58b4ba768c
If the IP header length does not match the size of the UDP packet received
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via the raw socket, print both lengths in the warning message.
2014-04-15 15:23:52 -04:00
Nicholas J. Kain
6804be2277
Use safe_sendto where necessary, and check for short writes.
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Also, change many log_lines to log_errors, mostly in ifset.c.
2014-04-07 04:15:02 -04:00
Nicholas J. Kain
b761889025
Move source from ndhc/ to src/ since ifchd is no longer a separate program.
2014-04-06 16:57:06 -04:00
