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if INCGUARD_06BMkSmD5M3PQVff then
error( "Module loaded twice: E_20230526154810" )
else
INCGUARD_06BMkSmD5M3PQVff = true
local CONTENT_TYPE_MULTIGET_RESPONSE = "application/multiget-response"
local MGET_CONTENT_CHUNK = 0x15
local MGET_CONTENT_TYPE = 0x0B
local MGET_EOF = 0x1B
local MGET_PATH = 0x01
local log = io.stderr
local attachInfoToTree, collectInfo, dissector, dissectorProtected, init, seal
function init()
local app = seal{
proto = Proto("Multiget", "Nsync Multiget Response"),
field_frameNr = Field.new("frame.number"),
field_tcpStrm = Field.new("tcp.stream"),
field_httpReqMth = Field.new("http.request.method"),
field_httpRspCode = Field.new("http.response.code"),
field_path = ProtoField.string("multiget.path", "Path"),
field_cType = ProtoField.string("multiget.contentType", "Content Type"),
field_chunk = ProtoField.string("multiget.chunk", "Chunk"),
field_eof = ProtoField.string("multiget.eof", "EOF"),
field_error = ProtoField.string("multiget.error", "Error"),
frameNrMax = 0,
tcpBuf = {}, -- key=tcpStream+srcPort val=string - half-baked buffer from last packet
prevReqContentType = {},
prevRspContentType = {},
frameInfo = {}, -- key=frameNr val=info
}
app.proto.fields = {
app.field_path, app.field_cType, app.field_chunk, app.field_eof, app.field_error
}
app.proto.dissector = function(...)return dissectorProtected(app, ...)end
DissectorTable.get("media_type"):add(CONTENT_TYPE_MULTIGET_RESPONSE, app.proto)
end
-- I disagree that concealing errors is funny. Therefore I prefer to
-- make them visible again with help of this workaround.
function dissectorProtected( app, ... )
local ok, a, b, c = pcall(dissector, app, ...)
if not ok then
log:write("[ERROR] "..(a or"nil").."\n")
error(a)
else
return a, b, c
end
end
function dissector( app, buf, pinfo, tree )
local frameNr = app.field_frameNr().value
local info = app.frameInfo[frameNr]
if not info then
--log:write("[DEBUG] Dissect frame "..tostring(frameNr).."\n")
if frameNr <= app.frameNrMax then
log:write("[WARN ] frameNr "..frameNr.." unexpectedly smaller than ".. app.frameNrMax .."\n")
end
app.frameNrMax = frameNr
collectInfo(app, buf, pinfo, tree)
end
attachInfoToTree(app, frameNr, buf, pinfo, tree)
end
function collectInfo( app, buf, pinfo, tree )
local frameNr = app.field_frameNr().value
assert(app.frameInfo[frameNr] == nil)
local info = seal{
mgetMsgs = {},
}
app.frameInfo[frameNr] = info
--
local tcpStream = app.field_tcpStrm()
if not tcpStream then return --[[TODO Why is tcpStream nil?]] end
tcpStream = tcpStream.value
--if #app.oldBuf > 0 then log:write("[WARN ] TODO oldBuf has data. Use it!\n") end
--
local off = 0
local raw = buf:raw()
while true do
local msg = {
msgOff = off, msgLen = raw:len() - off,
errStr = false,
tagOff = false, tagLen = false, tag = false,
lenOff = false, lenLen = false, len = false,
}
msg.tag = buf(off, 1):uint()
if msg.tag > 0x7F then -- TODO
log:write("[WARN ] Multibyte tag val (".. tostring(msg.tag) ..") not impl yet!\n")
end
msg.tagOff = off
msg.tagLen = 1 -- TODO multibyte support
off = off + 1
--log:write("Found multiget tag ".. tostring(msg.tag) .."\n")
local count, shift, len = 0, 0, 0
while true do
local b = buf(off, 1):uint();
len = bit.bor(len, (bit.lshift(bit.band(b, 0x7F), shift)))
off = off + 1; count = count + 1; shift = shift + 7
if bit.band(b, 0x80) == 0 then break end
if count > 8 then
msg.errStr = "Msg Length looks too large"
table.insert(info.mgetMsgs, msg)
return
end
end
msg.len = len
msg.lenOff = off - count
msg.lenLen = count
msg.valOff = off
msg.valLen = len
off = off + len
msg.msgLen = off - msg.msgOff
table.insert(info.mgetMsgs, msg)
---
if off == raw:len() then break end
assert(off < raw:len())
end
end
function attachInfoToTree( app, frameNr, buf, pinfo, tree )
local info = app.frameInfo[frameNr]
local protoTree = tree:add(app.proto, buf(), "Nsync Multiget Protocol")
for _, mgetMsg in ipairs(info.mgetMsgs) do
local tileStr = "Nsync Multiget Message"
if mgetMsg.errStr then tileStr = tileStr .." (ERROR)" end
local msgTree = protoTree:add(app.proto, buf(mgetMsg.msgOff, mgetMsg.msgLen), tileStr)
if mgetMsg.errStr then
local msg = "ERROR: ".. mgetMsg.errStr
msgTree:add(buf(mgetMsg.tagOff,buf:raw():len()-mgetMsg.tagOff), msg)
msgTree:add(app.field_error, msg)
else
local tagStr, fieldFunc
if mgetMsg.tag == MGET_PATH then
tagStr = "Type PATH (0x01)"
fieldFunc = app.field_path
elseif mgetMsg.tag == MGET_CONTENT_TYPE then
tagStr = "Type CONTENT_TYPE (0x0B)"
fieldFunc = app.field_cType
elseif mgetMsg.tag == MGET_CONTENT_CHUNK then
tagStr = "Type CONTENT_CHUNK (0x15)"
fieldFunc = app.field_chunk
elseif mgetMsg.tag == MGET_EOF then
tagStr = "Type EOF (0x1B)"
fieldFunc = app.field_eof
else
tagStr = "N/A ("..tostring(mgetMsg.tag)..")"
fieldFunc = app.field_error
end
msgTree:add(buf(mgetMsg.tagOff,mgetMsg.tagLen), tagStr)
msgTree:add(buf(mgetMsg.lenOff,mgetMsg.lenLen), "Length ".. mgetMsg.len .." bytes")
msgTree:add(fieldFunc, buf(mgetMsg.valOff, mgetMsg.valLen))
--
end
end
end
function seal(obj)
return setmetatable(obj, {
__index = function(t,k,v)error("No such field '"..(k or"nil").."'")end,
__newindex = function(t,k,v)error("No such field '"..(k or"nil").."'")end,
})
end
init()
end -- INCGUARD_06BMkSmD5M3PQVff
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