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net, wgengine/capture: encode NAT addresses in pcap stream

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Signed-off-by: Tom DNetto <tom@tailscale.com>
This commit is contained in:
Tom DNetto
2023-03-30 12:39:39 -07:00
committed by Tom
parent 92459a9248
commit 6a627e5a33
7 changed files with 94 additions and 28 deletions
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28
wgengine/capture/ts-dissector.lua
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@@ -4,7 +4,11 @@ end
tsdebug_ll = Proto("tsdebug", "Tailscale debug")
PATH = ProtoField.string("tsdebug.PATH","PATH", base.ASCII)
tsdebug_ll.fields = {PATH}
SNAT_IP_4 = ProtoField.ipv4("tsdebug.SNAT_IP_4", "Pre-NAT Source IPv4 address")
SNAT_IP_6 = ProtoField.ipv4("tsdebug.SNAT_IP_6", "Pre-NAT Source IPv6 address")
DNAT_IP_4 = ProtoField.ipv4("tsdebug.DNAT_IP_4", "Pre-NAT Dest IPv4 address")
DNAT_IP_6 = ProtoField.ipv4("tsdebug.DNAT_IP_6", "Pre-NAT Dest IPv6 address")
tsdebug_ll.fields = {PATH, SNAT_IP_4, SNAT_IP_6, DNAT_IP_4, DNAT_IP_6}
function tsdebug_ll.dissector(buffer, pinfo, tree)
pinfo.cols.protocol = tsdebug_ll.name
@@ -14,14 +18,28 @@ function tsdebug_ll.dissector(buffer, pinfo, tree)
-- -- Get path UINT16
local path_id = buffer:range(offset, 2):le_uint()
if path_id == 0 then subtree:add(PATH, "FromLocal")
elseif path_id == 1 then subtree:add(PATH, "FromPeer")
elseif path_id == 2 then subtree:add(PATH, "Synthesized (Inbound / ToLocal)")
elseif path_id == 3 then subtree:add(PATH, "Synthesized (Outbound / ToPeer)")
if path_id == 0 then subtree:add(PATH, "FromLocal")
elseif path_id == 1 then subtree:add(PATH, "FromPeer")
elseif path_id == 2 then subtree:add(PATH, "Synthesized (Inbound / ToLocal)")
elseif path_id == 3 then subtree:add(PATH, "Synthesized (Outbound / ToPeer)")
elseif path_id == 254 then subtree:add(PATH, "Disco frame")
end
offset = offset + 2
-- -- Get SNAT address
local snat_addr_len = buffer:range(offset, 1):le_uint()
if snat_addr_len == 4 then subtree:add(SNAT_IP_4, buffer:range(offset + 1, snat_addr_len))
elseif snat_addr_len > 0 then subtree:add(SNAT_IP_6, buffer:range(offset + 1, snat_addr_len))
end
offset = offset + 1 + snat_addr_len
-- -- Get DNAT address
local dnat_addr_len = buffer:range(offset, 1):le_uint()
if dnat_addr_len == 4 then subtree:add(DNAT_IP_4, buffer:range(offset + 1, dnat_addr_len))
elseif dnat_addr_len > 0 then subtree:add(DNAT_IP_6, buffer:range(offset + 1, dnat_addr_len))
end
offset = offset + 1 + dnat_addr_len
-- -- Handover rest of data to lower-level dissector
local data_buffer = buffer:range(offset, packet_length-offset):tvb()
if path_id == 254 then