*** From dhcp-server -- To unsubscribe, see the end of this message. ***
I don't actually see anything bad about the packet that's being sent
to the client, but it's possible that the checksum is screwed up. I
will be releasing a new patchlevel that fixes the UDP checksum bug
shortly, but since you're losing right now, here's a patch that should
bring you up to the latest version of packet.c, with the correct UDP
checksum.
_MelloN_
Index: packet.c
===================================================================
RCS file: /proj/src/isc/cvs-1/DHCP/common/packet.c,v
retrieving revision 1.18.2.2
retrieving revision 1.18.2.4
diff -c -r1.18.2.2 -r1.18.2.4
*** packet.c 1999/03/26 16:52:39 1.18.2.2
--- packet.c 1999/04/24 15:31:47 1.18.2.4
***************
*** 42,48 ****
#ifndef lint
static char copyright[] =
! "$Id: packet.c,v 1.18.2.2 1999/03/26 16:52:39 mellon Exp $ Copyright (c) 1996 The
Internet Software Consortium. All rights reserved.\n";
#endif /* not lint */
#include "dhcpd.h"
--- 42,48 ----
#ifndef lint
static char copyright[] =
! "$Id: packet.c,v 1.18.2.4 1999/04/24 15:31:47 mellon Exp $ Copyright (c) 1996 The
Internet Software Consortium. All rights reserved.\n";
#endif /* not lint */
#include "dhcpd.h"
***************
*** 72,77 ****
--- 72,80 ----
debug ("sum = %x", sum);
#endif
sum += (u_int16_t) ntohs(*((u_int16_t *)(buf + i)));
+ /* Add carry. */
+ if (sum > 0xFFFF)
+ sum -= 0xFFFF;
}
/* If there's a single byte left over, checksum it, too. Network
***************
*** 81,93 ****
debug ("sum = %x", sum);
#endif
sum += buf [i] << 8;
}
return sum;
}
! /* Fold the upper sixteen bits of the checksum down into the lower bits,
! complement the sum, and then put it into network byte order. */
u_int32_t wrapsum (sum)
u_int32_t sum;
--- 84,98 ----
debug ("sum = %x", sum);
#endif
sum += buf [i] << 8;
+ /* Add carry. */
+ if (sum > 0xFFFF)
+ sum -= 0xFFFF;
}
return sum;
}
! /* Finish computing the sum, and then put it into network byte order. */
u_int32_t wrapsum (sum)
u_int32_t sum;
***************
*** 96,113 ****
debug ("wrapsum (%x)", sum);
#endif
! while (sum > 0x10000) {
! sum = (sum >> 16) + (sum & 0xFFFF);
#ifdef DEBUG_CHECKSUM_VERBOSE
- debug ("sum = %x", sum);
- #endif
- sum += (sum >> 16);
- #ifdef DEBUG_CHECKSUM_VERBOSE
- debug ("sum = %x", sum);
- #endif
- }
- sum = sum ^ 0xFFFF;
- #ifdef DEBUG_CHECKSUM_VERBOSE
debug ("sum = %x", sum);
#endif
--- 101,108 ----
debug ("wrapsum (%x)", sum);
#endif
! sum = ~sum & 0xFFFF;
#ifdef DEBUG_CHECKSUM_VERBOSE
debug ("sum = %x", sum);
#endif
***************
*** 237,256 ****
/* UDP header and IP header decoded together for convenience. */
! ssize_t decode_udp_ip_header (interface, buf, bufix, from, data, len)
struct interface_info *interface;
unsigned char *buf;
int bufix;
struct sockaddr_in *from;
unsigned char *data;
! int len;
{
struct ip *ip;
struct udphdr *udp;
u_int32_t ip_len = (buf [bufix] & 0xf) << 2;
u_int32_t sum, usum;
! static int packets_seen;
! static int packets_bad_checksum;
ip = (struct ip *)(buf + bufix);
udp = (struct udphdr *)(buf + bufix + ip_len);
--- 232,256 ----
/* UDP header and IP header decoded together for convenience. */
! ssize_t decode_udp_ip_header (interface, buf, bufix, from, data, buflen)
struct interface_info *interface;
unsigned char *buf;
int bufix;
struct sockaddr_in *from;
unsigned char *data;
! int buflen;
{
struct ip *ip;
struct udphdr *udp;
u_int32_t ip_len = (buf [bufix] & 0xf) << 2;
u_int32_t sum, usum;
! static int ip_packets_seen;
! static int ip_packets_bad_checksum;
! static int udp_packets_seen;
! static int udp_packets_bad_checksum;
! static int udp_packets_length_checked;
! static int udp_packets_length_overflow;
! int len;
ip = (struct ip *)(buf + bufix);
udp = (struct udphdr *)(buf + bufix + ip_len);
***************
*** 266,279 ****
#endif /* USERLAND_FILTER */
/* Check the IP header checksum - it should be zero. */
if (wrapsum (checksum (buf + bufix, ip_len, 0))) {
! if (packets_seen &&
! (++packets_seen / ++packets_bad_checksum) < 2)
! note ("Bad IP checksum: %x",
! wrapsum (checksum (buf + bufix, sizeof *ip, 0)));
return -1;
}
/* Copy out the IP source address... */
memcpy (&from -> sin_addr, &ip -> ip_src, 4);
--- 266,288 ----
#endif /* USERLAND_FILTER */
/* Check the IP header checksum - it should be zero. */
+ ++ip_packets_seen;
if (wrapsum (checksum (buf + bufix, ip_len, 0))) {
! ++ip_packets_bad_checksum;
! if (ip_packets_seen > 4 &&
! (ip_packets_seen / ip_packets_bad_checksum) < 2) {
! note ("%d bad IP checksums seen in %d packets",
! ip_packets_bad_checksum, ip_packets_seen);
! ip_packets_seen = ip_packets_bad_checksum = 0;
! }
return -1;
}
+ /* Check the IP packet length. */
+ if (ntohs (ip -> ip_len) != buflen)
+ debug ("ip length %d disagrees with bytes received %d.",
+ ntohs (ip -> ip_len), buflen);
+
/* Copy out the IP source address... */
memcpy (&from -> sin_addr, &ip -> ip_src, 4);
***************
*** 283,289 ****
if (!data) {
data = buf + bufix + ip_len + sizeof *udp;
! len -= ip_len + sizeof *udp;
}
usum = udp -> uh_sum;
--- 292,314 ----
if (!data) {
data = buf + bufix + ip_len + sizeof *udp;
! len = ntohs (udp -> uh_ulen) - sizeof *udp;
! ++udp_packets_length_checked;
! if (len + data > buf + bufix + buflen) {
! ++udp_packets_length_overflow;
! if (udp_packets_length_checked > 4 &&
! (udp_packets_length_checked /
! udp_packets_length_overflow) < 2) {
! note ("%d udp packets in %d too long - dropped",
! udp_packets_length_overflow,
! udp_packets_length_checked);
! udp_packets_length_overflow =
! udp_packets_length_checked = 0;
! }
! return -1;
! }
! if (len + data != buf + bufix + buflen)
! debug ("accepting packet with data after udp payload.");
}
usum = udp -> uh_sum;
***************
*** 298,309 ****
(u_int32_t)
ntohs (udp -> uh_ulen)))));
if (usum && usum != sum) {
! static int packets_seen;
! static int packets_bad_checksum;
! if (packets_seen &&
! (++packets_seen / ++packets_bad_checksum) < 2)
! note ("Bad udp checksum: %x %x", usum, sum);
return -1;
}
--- 323,337 ----
(u_int32_t)
ntohs (udp -> uh_ulen)))));
+ udp_packets_seen++;
if (usum && usum != sum) {
! udp_packets_bad_checksum++;
! if (udp_packets_seen > 4 &&
! (udp_packets_seen / udp_packets_bad_checksum) < 2) {
! note ("%d bad udp checksums in %d packets",
! udp_packets_bad_checksum, udp_packets_seen);
! udp_packets_seen = udp_packets_bad_checksum = 0;
! }
return -1;
}
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