Wireshark · Ethereal-dev: [ethereal-dev] Change to bit-swap FDDI MAC addresses checked in

[guy@xxxxxxxxxx (Guy Harris)]

On most systems, bit-swap the bytes of an FDDI MAC address.  (List of
systems on which you don't bit-swap them taken from "tcpdump"; the list
may not be complete.  If you discover any systems to be added to that
list, you might want to tell the maintainers of "tcpdump" about it; see
"print-fddi.c" in the "tcpdump" source.)

There may be other 802.3-like media on which bit-swapping is required;
if so, "get_mac_addr()" should be made public, and used by the
"dissect_XXX()" routines for those media as well.

Here's the patch.

Index: packet-fddi.c
===================================================================
RCS file: /usr/local/cvsroot/ethereal/packet-fddi.c,v
retrieving revision 1.4
diff -c -r1.4 packet-fddi.c
*** packet-fddi.c	1998/10/13 05:55:45	1.4
--- packet-fddi.c	1998/10/13 07:46:22
***************
*** 74,95 ****
  #define FDDI_P_DHOST		1
  #define FDDI_P_SHOST		7
  
! void dissect_fddi(const u_char *pd, frame_data *fd, GtkTree *tree) 
  {
  
    int        offset = 0, fc;
    GtkWidget *fh_tree, *ti;
  
    if (fd->cap_len < FDDI_HEADER_SIZE) {
      dissect_data(pd, offset, fd, tree);
      return;
    }
  
    fc = (int) pd[FDDI_P_FC];
  
    if (fd->win_info[COL_NUM]) {
!     strcpy(fd->win_info[COL_DESTINATION], get_ether_name((u_char *)&pd[FDDI_P_DHOST]));
!     strcpy(fd->win_info[COL_SOURCE], get_ether_name((u_char *)&pd[FDDI_P_SHOST]));
      strcpy(fd->win_info[COL_INFO], "FDDI");
    }
  
--- 74,156 ----
  #define FDDI_P_DHOST		1
  #define FDDI_P_SHOST		7
  
! /* On some systems, the FDDI MAC addresses are bit-swapped. */
! #if !defined(ultrix) && !defined(__alpha) && !defined(__bsdi)
! #define BIT_SWAPPED_MAC_ADDRS
! #endif
! 
! #ifdef BIT_SWAPPED_MAC_ADDRS
! /* "swaptab[i]" is the value of "i" with the bits reversed. */
! static u_char swaptab[256] = {
!   0x00, 0x80, 0x40, 0xc0, 0x20, 0xa0, 0x60, 0xe0,
!   0x10, 0x90, 0x50, 0xd0, 0x30, 0xb0, 0x70, 0xf0,
!   0x08, 0x88, 0x48, 0xc8, 0x28, 0xa8, 0x68, 0xe8,
!   0x18, 0x98, 0x58, 0xd8, 0x38, 0xb8, 0x78, 0xf8,
!   0x04, 0x84, 0x44, 0xc4, 0x24, 0xa4, 0x64, 0xe4,
!   0x14, 0x94, 0x54, 0xd4, 0x34, 0xb4, 0x74, 0xf4,
!   0x0c, 0x8c, 0x4c, 0xcc, 0x2c, 0xac, 0x6c, 0xec,
!   0x1c, 0x9c, 0x5c, 0xdc, 0x3c, 0xbc, 0x7c, 0xfc,
!   0x02, 0x82, 0x42, 0xc2, 0x22, 0xa2, 0x62, 0xe2,
!   0x12, 0x92, 0x52, 0xd2, 0x32, 0xb2, 0x72, 0xf2,
!   0x0a, 0x8a, 0x4a, 0xca, 0x2a, 0xaa, 0x6a, 0xea,
!   0x1a, 0x9a, 0x5a, 0xda, 0x3a, 0xba, 0x7a, 0xfa,
!   0x06, 0x86, 0x46, 0xc6, 0x26, 0xa6, 0x66, 0xe6,
!   0x16, 0x96, 0x56, 0xd6, 0x36, 0xb6, 0x76, 0xf6,
!   0x0e, 0x8e, 0x4e, 0xce, 0x2e, 0xae, 0x6e, 0xee,
!   0x1e, 0x9e, 0x5e, 0xde, 0x3e, 0xbe, 0x7e, 0xfe,
!   0x01, 0x81, 0x41, 0xc1, 0x21, 0xa1, 0x61, 0xe1,
!   0x11, 0x91, 0x51, 0xd1, 0x31, 0xb1, 0x71, 0xf1,
!   0x09, 0x89, 0x49, 0xc9, 0x29, 0xa9, 0x69, 0xe9,
!   0x19, 0x99, 0x59, 0xd9, 0x39, 0xb9, 0x79, 0xf9,
!   0x05, 0x85, 0x45, 0xc5, 0x25, 0xa5, 0x65, 0xe5,
!   0x15, 0x95, 0x55, 0xd5, 0x35, 0xb5, 0x75, 0xf5,
!   0x0d, 0x8d, 0x4d, 0xcd, 0x2d, 0xad, 0x6d, 0xed,
!   0x1d, 0x9d, 0x5d, 0xdd, 0x3d, 0xbd, 0x7d, 0xfd,
!   0x03, 0x83, 0x43, 0xc3, 0x23, 0xa3, 0x63, 0xe3,
!   0x13, 0x93, 0x53, 0xd3, 0x33, 0xb3, 0x73, 0xf3,
!   0x0b, 0x8b, 0x4b, 0xcb, 0x2b, 0xab, 0x6b, 0xeb,
!   0x1b, 0x9b, 0x5b, 0xdb, 0x3b, 0xbb, 0x7b, 0xfb,
!   0x07, 0x87, 0x47, 0xc7, 0x27, 0xa7, 0x67, 0xe7,
!   0x17, 0x97, 0x57, 0xd7, 0x37, 0xb7, 0x77, 0xf7,
!   0x0f, 0x8f, 0x4f, 0xcf, 0x2f, 0xaf, 0x6f, 0xef,
!   0x1f, 0x9f, 0x5f, 0xdf, 0x3f, 0xbf, 0x7f, 0xff,
! };
! #endif
! 
! static void get_mac_addr(u_char *swapped_addr, const u_char *addr)
  {
+   int i;
+ 
+   for (i = 0; i < 6; i++) {
+ #ifdef BIT_SWAPPED_MAC_ADDRS
+     swapped_addr[i] = swaptab[addr[i]];
+ #else
+     swapped_addr[i] = addr[i];
+ #endif
+   }
+ }
  
+ void dissect_fddi(const u_char *pd, frame_data *fd, GtkTree *tree) 
+ {
    int        offset = 0, fc;
    GtkWidget *fh_tree, *ti;
+   u_char     src[6], dst[6];
  
    if (fd->cap_len < FDDI_HEADER_SIZE) {
      dissect_data(pd, offset, fd, tree);
      return;
    }
  
+   /* Extract the source and destination addresses, possibly bit-swapping
+      them. */
+   get_mac_addr(dst, (u_char *)&pd[FDDI_P_DHOST]);
+   get_mac_addr(src, (u_char *)&pd[FDDI_P_SHOST]);
+ 
    fc = (int) pd[FDDI_P_FC];
  
    if (fd->win_info[COL_NUM]) {
!     strcpy(fd->win_info[COL_DESTINATION], get_ether_name(dst));
!     strcpy(fd->win_info[COL_SOURCE], get_ether_name(src));
      strcpy(fd->win_info[COL_INFO], "FDDI");
    }
  
***************
*** 103,113 ****
        add_subtree(ti, fh_tree, ETT_FDDI);
        add_item_to_tree(fh_tree, FDDI_P_FC, 1, "Frame Control: 0x%02x", fc);
        add_item_to_tree(fh_tree, FDDI_P_DHOST, 6, "Destination: %s (%s)",
! 		       ether_to_str((guint8 *) &pd[FDDI_P_DHOST]),
! 		       get_ether_name((u_char *) &pd[FDDI_P_DHOST]));
        add_item_to_tree(fh_tree, FDDI_P_SHOST, 6, "Source: %s (%s)",
! 		       ether_to_str((guint8 *) &pd[FDDI_P_SHOST]),
! 		       get_ether_name((u_char *)&pd[FDDI_P_SHOST]));
      }
  
    offset = FDDI_HEADER_SIZE;
--- 164,172 ----
        add_subtree(ti, fh_tree, ETT_FDDI);
        add_item_to_tree(fh_tree, FDDI_P_FC, 1, "Frame Control: 0x%02x", fc);
        add_item_to_tree(fh_tree, FDDI_P_DHOST, 6, "Destination: %s (%s)",
! 		       ether_to_str(dst), get_ether_name(dst));
        add_item_to_tree(fh_tree, FDDI_P_SHOST, 6, "Source: %s (%s)",
! 		       ether_to_str(src), get_ether_name(src));
      }
  
    offset = FDDI_HEADER_SIZE;