changelog: document changes since 0.6.0

[secnet.git] / secnet-wireshark.lua

diff --git a/secnet-wireshark.lua b/secnet-wireshark.lua
index c9b25d2358bbc9f9750ac9460ce1058f2c45358e..62739bc9aaece9db118d137464c7fb2ed97dac9a 100644 (file)
--- a/secnet-wireshark.lua
+++ b/secnet-wireshark.lua
@@ -262,20 +262,53 @@ end
 local PF = { } -- The table of protocol fields, filled in later.
 local F = { } -- A table of field values, also filled in later.
 
+local function msgcode(major, minor)
+  -- Construct a Secnet message number according to the complicated rules.
+
+  local majlo = bit.band(major, 0x000f)
+  local majhi = bit.band(major, 0xfff0)
+  local minlo = bit.band(minor, 0x000f)
+  local minhi = bit.band(minor, 0xfff0)
+  return bit.bxor(bit.lshift(majlo,  0),
+                 bit.lshift(majlo,  8),
+                 bit.lshift(majlo, 16),
+                 bit.lshift(majlo, 24),
+                 bit.lshift(majhi,  4),
+                 bit.lshift(minlo,  4),
+                 bit.lshift(minlo, 28),
+                 bit.lshift(minhi, 16))
+end
+
+local function msgmajor(label)
+  -- Return the major message number from a LABEL.
+
+  local lo = bit.band(label, 0x000f)
+  local hi = bit.band(bit.rshift(label, 4), 0xfff0)
+  return bit.bxor(lo, bit.lshift(lo, 4), bit.lshift(lo, 12), hi)
+end
+
+local function msgminor(label)
+  -- Return the minor message number from a LABEL.
+
+  return bit.bxor(bit.lshift(bit.band(label, 0x00ff), 8),
+                 bit.band(bit.rshift(label, 4), 0x000f),
+                 bit.band(bit.rshift(label, 16), 0xfff0))
+end
+
 -- Main message-number table.
-local M = { NAK                = 0x00000000
-           MSG0        = 0x00020200
-           MSG1        = 0x01010101
-           MSG2        = 0x02020202
-           MSG3        = 0x03030303
-           MSG3BIS     = 0x13030313
-           MSG4        = 0x04040404
-           MSG5        = 0x05050505
-           MSG6        = 0x06060606
-           MSG7        = 0x07070707
-           MSG8        = 0x08080808
-           MSG9        = 0x09090909
-           PROD        = 0x0a0a0a0a }
+local M = { NAK                = msgcode(     0, 0),
+           MSG0        = msgcode(0x2020, 0), -- !
+           MSG1        = msgcode(     1, 0),
+           MSG2        = msgcode(     2, 0),
+           MSG3        = msgcode(     3, 0),
+           MSG3BIS     = msgcode(     3, 1),
+           MSG4        = msgcode(     4, 0),
+           MSG5        = msgcode(     5, 0),
+           MSG6        = msgcode(     6, 0),
+           MSG7        = msgcode(     7, 0),
+           MSG8        = msgcode(     8, 0),
+           MSG9        = msgcode(     9, 0),
+           PROD        = msgcode(    10, 0)}
 
 -- The `dissect_*' functions follow a common protocol.  They parse a thing
 -- from a packet buffer BUF, of size SZ, starting from POS, and store