[Etherboot-developers] Uninitialized 'iplen' in nic.c

[Robb M. <ma...@ac...>]

Attached patch against etherboot-5.1.8 corrects a coding issue in
await_reply() that could (in a bizarre set of circumstances) use the
variable 'iplen' without it being initialized. I doubt this would ever occur
in practice, but....
I submit the attached patch for cleanliness.

BTW - I have commence hacking NIC.C into pieces (slicing down protocol
lines). So far, I have created:
- dhcp.c
- ip.c
- mcast.c
- rarp.c
- tftp.c
- udp.c
, and have retained the balance of (appropriate) code in 'nic.c'.
I have modified the Makefile, and have successfully rebuilt, although I have
yet to resolve a slight increase in compiled filesize. Next step is to build
a UDP test message application, then on to memtest86 & syslog.

Cheers,
Robb.

---------------------------------
*** nic_org.c Thu May  1 21:32:52 2003
--- nic.c Thu May  1 21:38:09 2003
***************
*** 1032,1037 ****
--- 1032,1038 ----
    } else continue; /* what else could we do with it? */
    /* Verify an IP header */
    ip = 0;
+   udp = 0;
    if ((ptype == IP) && (nic.packetlen >= ETH_HLEN + sizeof(struct iphdr)))
{
     unsigned ipoptlen;
     ip = (struct iphdr *)&nic.packet[ETH_HLEN];
***************
*** 1061,1081 ****
       nic.packetlen - ipoptlen);
      nic.packetlen -= ipoptlen;
     }
!   }
!   udp = 0;
!   if (ip && (ip->protocol == IP_UDP) &&
!    (nic.packetlen >=
!    ETH_HLEN + sizeof(struct iphdr) + sizeof(struct udphdr))) {
!    udp = (struct udphdr *)&nic.packet[ETH_HLEN + sizeof(struct iphdr)];

!    /* Make certain we have a reasonable packet length */
!    if (ntohs(udp->len) > (ntohs(ip->len) - iplen))
!     continue;

!    if (udp->chksum && udpchksum(ip, udp)) {
!     printf("UDP checksum error\n");
!     continue;
!    }
    }
    result = reply(ival, ptr, ptype, ip, udp);
    if (result > 0) {
--- 1062,1081 ----
       nic.packetlen - ipoptlen);
      nic.packetlen -= ipoptlen;
     }
!    if ((ip->protocol == IP_UDP) &&
!     (nic.packetlen >=
!     ETH_HLEN + sizeof(struct iphdr) + sizeof(struct udphdr))) {
!     udp = (struct udphdr *)&nic.packet[ETH_HLEN + sizeof(struct iphdr)];

!     /* Make certain we have a reasonable packet length */
!     if (ntohs(udp->len) > (ntohs(ip->len) - iplen))
!      continue;

!     if (udp->chksum && udpchksum(ip, udp)) {
!      printf("UDP checksum error\n");
!      continue;
!     }
!           }
    }
    result = reply(ival, ptr, ptype, ip, udp);
    if (result > 0) {
---------------------------------