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l2tp.lua: indent with spaces
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@capr
capr committed Nov 16, 2015
1 parent a58b0a2 commit 766da75
Showing 1 changed file with 106 additions and 111 deletions.
217 changes: 106 additions & 111 deletions src/program/lisper/dev-env/l2tp.lua
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Original file line number Diff line number Diff line change
@@ -1,91 +1,91 @@
#!/usr/bin/env luajit
io.stdout:setvbuf'no'
io.stderr:setvbuf'no'

--L2TP IP-over-IPv6 tunnelling program for testing.

local function assert(v, ...)
if v then return v, ... end
error(tostring((...)), 2)
end

local ffi = require'ffi'
local S = require'syscall'
local C = ffi.C
local htons = require'syscall.helpers'.htons

local DEBUG = false

local function assert(v, ...)
if v then return v, ... end
error(tostring((...)), 2)
end

local function hex(s)
return (s:gsub('(.)(.?)', function(c1, c2)
return c2 and #c2 == 1 and
string.format('%02x%02x ', c1:byte(), c2:byte()) or
string.format('%02x ', c1:byte())
end))
return (s:gsub('(.)(.?)', function(c1, c2)
return c2 and #c2 == 1 and
string.format('%02x%02x ', c1:byte(), c2:byte()) or
string.format('%02x ', c1:byte())
end))
end

local digits = {}
for i=0,9 do digits[string.char(('0'):byte()+i)] = i end
for i=0,5 do digits[string.char(('a'):byte()+i)] = 10+i end
for i=0,5 do digits[string.char(('A'):byte()+i)] = 10+i end
local function parsehex(s)
return (s:gsub('[%s%:%.]*(%x)(%x)[%s%:%.]*', function(hi, lo)
local hi = digits[hi]
local lo = digits[lo]
return string.char(lo + hi * 16)
end))
return (s:gsub('[%s%:%.]*(%x)(%x)[%s%:%.]*', function(hi, lo)
local hi = digits[hi]
local lo = digits[lo]
return string.char(lo + hi * 16)
end))
end

local function open_tap(name)
local fd = assert(S.open('/dev/net/tun', 'rdwr, nonblock'))
local ifr = S.t.ifreq{flags = 'tap, no_pi', name = name}
assert(fd:ioctl('tunsetiff', ifr))
return fd
local fd = assert(S.open('/dev/net/tun', 'rdwr, nonblock'))
local ifr = S.t.ifreq{flags = 'tap, no_pi', name = name}
assert(fd:ioctl('tunsetiff', ifr))
return fd
end

local function open_raw(name)
local fd = assert(S.socket('packet', 'raw, nonblock', htons(S.c.ETH_P.all)))
local ifr = S.t.ifreq{name = name}
assert(S.ioctl(fd, 'siocgifindex', ifr))
assert(S.bind(fd, S.t.sockaddr_ll{
ifindex = ifr.ivalue,
protocol = 'all'}))
return fd
local fd = assert(S.socket('packet', 'raw, nonblock', htons(S.c.ETH_P.all)))
local ifr = S.t.ifreq{name = name}
assert(S.ioctl(fd, 'siocgifindex', ifr))
assert(S.bind(fd, S.t.sockaddr_ll{
ifindex = ifr.ivalue,
protocol = 'all'}))
return fd
end

local function can_read(...)
return assert(S.select({readfds = {...}}, 0)).count == 1
return assert(S.select({readfds = {...}}, 0)).count == 1
end

local function can_write(...)
return assert(S.select({writefds = {...}}, 0)).count == 1
return assert(S.select({writefds = {...}}, 0)).count == 1
end

local mtu = 1500
local buf = ffi.new('uint8_t[?]', mtu)
local function read(fd)
local len = assert(S.read(fd, buf, mtu))
return ffi.string(buf, len)
local len = assert(S.read(fd, buf, mtu))
return ffi.string(buf, len)
end

local function write(fd, s, len)
assert(S.write(fd, s, len or #s))
assert(S.write(fd, s, len or #s))
end

local function close(fd)
S.close(fd)
S.close(fd)
end

local tapname, ethname, smac, dmac, sip, dip, sid, did = ...
if not (tapname and ethname and smac and dmac and sip and dip and sid and did) then
print('Usage: '..arg[0]..' TAP ETH SMAC DMAC SIP DIP SID DID')
print' TAP: the tunneled interface: will be created if not present.'
print' ETH: the tunneling interface: must have an IPv6 assigned.'
print' SMAC: the MAC address of ETH.'
print' DMAC: the MAC address of the gateway interface.'
print' SIP: the IPv6 of ETH (long form).'
print' DIP: the IPv6 of ETH at the other endpoint (long form).'
print' SID: session ID (hex)'
print' DID: peer session ID (hex)'
os.exit(1)
print('Usage: '..arg[0]..' TAP ETH SMAC DMAC SIP DIP SID DID')
print' TAP: the tunneled interface: will be created if not present.'
print' ETH: the tunneling interface: must have an IPv6 assigned.'
print' SMAC: the MAC address of ETH.'
print' DMAC: the MAC address of the gateway interface.'
print' SIP: the IPv6 of ETH (long form).'
print' DIP: the IPv6 of ETH at the other endpoint (long form).'
print' SID: session ID (hex)'
print' DID: peer session ID (hex)'
os.exit(1)
end
smac = parsehex(smac)
dmac = parsehex(dmac)
Expand All @@ -107,79 +107,74 @@ print('sid ', hex(sid))
print('did ', hex(did))

local function decap_l2tp(s)
local dmac = s:sub(1, 1+6-1)
local smac = s:sub(1+6, 1+6+6-1)
local eth_proto = s:sub(1+6+6, 1+6+6+2-1)
if eth_proto ~= '\x86\xdd' then
return nil, 'invalid eth_proto '..hex(eth_proto)
end --not ipv6
local ipv6_proto = s:sub(21, 21)
if ipv6_proto ~= '\115' then
return nil, 'invalid ipv6_proto '..hex(ipv6_proto)
end --not l2tp
local sip = s:sub(23, 23+16-1)
local dip = s:sub(23+16, 23+16+16-1)
local sid = s:sub(55, 55+4-1)
local payload = s:sub(67)
return smac, dmac, sip, dip, sid, payload
local dmac = s:sub(1, 1+6-1)
local smac = s:sub(1+6, 1+6+6-1)
local eth_proto = s:sub(1+6+6, 1+6+6+2-1)
if eth_proto ~= '\x86\xdd' then
return nil, 'invalid eth_proto '..hex(eth_proto)
end --not ipv6
local ipv6_proto = s:sub(21, 21)
if ipv6_proto ~= '\115' then
return nil, 'invalid ipv6_proto '..hex(ipv6_proto)
end --not l2tp
local sip = s:sub(23, 23+16-1)
local dip = s:sub(23+16, 23+16+16-1)
local sid = s:sub(55, 55+4-1)
local payload = s:sub(67)
return smac, dmac, sip, dip, sid, payload
end

local function encap_l2tp(smac, dmac, sip, dip, did, payload)
local cookie = '\0\0\0\0\0\0\0\0'
local l2tp = did..cookie
local len = #payload + #l2tp
local len = string.char(bit.rshift(len, 8)) .. string.char(bit.band(len, 0xff))
local ipv6_proto = '\115' --l2tp
local maxhops = '\64'
local ipv6 = '\x60\0\0\0'..len..ipv6_proto..maxhops..sip..dip
local eth_proto = '\x86\xdd' --ipv6
local eth = dmac..smac..eth_proto
return eth..ipv6..l2tp..payload
local cookie = '\0\0\0\0\0\0\0\0'
local l2tp = did..cookie
local len = #payload + #l2tp
local len = string.char(bit.rshift(len, 8)) .. string.char(bit.band(len, 0xff))
local ipv6_proto = '\115' --l2tp
local maxhops = '\64'
local ipv6 = '\x60\0\0\0'..len..ipv6_proto..maxhops..sip..dip
local eth_proto = '\x86\xdd' --ipv6
local eth = dmac..smac..eth_proto
return eth..ipv6..l2tp..payload
end

while true do
if can_read(tap, raw) then
if can_read(raw) then
local s = read(raw)
local smac1, dmac1, sip1, dip1, did1, payload = decap_l2tp(s)
local accept = smac1
and smac1 == dmac
and dmac1 == smac
and dip1 == sip
and sip1 == dip
and did1 == sid
if DEBUG then
print('read ', accept and 'accepted' or
('rejected '..(smac1 and hex(dmac1) or dmac1)))
if accept then
print(' smac ', hex(smac1))
print(' dmac ', hex(dmac1))
print(' sip ', hex(sip1))
print(' dip ', hex(dip1))
print(' did ', hex(did1))
print(' # ', #payload)
end
end
if accept then
write(tap, payload)
end
end
if can_read(tap) then
local payload = read(tap)
local s = encap_l2tp(smac, dmac, sip, dip, did, payload)
if DEBUG then
print('write')
print(' smac ', hex(smac))
print(' dmac ', hex(dmac))
print(' sip ', hex(sip))
print(' dip ', hex(dip))
print(' did ', hex(did))
print(' # ', #payload)
print(hex(s))
end
write(raw, s)
end
end
if can_read(tap, raw) then
if can_read(raw) then
local s = read(raw)
local smac1, dmac1, sip1, dip1, did1, payload = decap_l2tp(s)
local accept = smac1
and smac1 == dmac
and dmac1 == smac
and dip1 == sip
and sip1 == dip
and did1 == sid
print('read ', accept and 'accepted' or
('rejected '..(smac1 and hex(dmac1) or dmac1)))
if accept then
print(' smac ', hex(smac1))
print(' dmac ', hex(dmac1))
print(' sip ', hex(sip1))
print(' dip ', hex(dip1))
print(' did ', hex(did1))
print(' # ', #payload)
end
if accept then
write(tap, payload)
end
end
if can_read(tap) then
local payload = read(tap)
local s = encap_l2tp(smac, dmac, sip, dip, did, payload)
print('write')
print(' smac ', hex(smac))
print(' dmac ', hex(dmac))
print(' sip ', hex(sip))
print(' dip ', hex(dip))
print(' did ', hex(did))
print(' # ', #payload)
write(raw, s)
end
end
end

tap:close()
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