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fix options decoding... decodes only if rdlen>0 #12

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fix options decoding... decodes only if rdlen>0 #12

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9f99bdd
ensure that option_data_length_hi is not nil before doing a lshift)
Jul 19, 2019
654d12f
Merge pull request #1 from andreaf74/option_bug_fix
andreaf74 Jul 20, 2019
0096ff8
Merge remote-tracking branch 'upstream/master'
Jul 23, 2019
d92e211
do not decode option if rdlen == 0
Jul 23, 2019
3294254
fixed EDNS0 opt_ver
Jul 23, 2019
fdc8b43
Added support to inserte request opts in response
andreaf74 Mar 3, 2020
b9a5996
Merge branch 'master' into options-decoding
andreaf74 Mar 14, 2023
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43 changes: 33 additions & 10 deletions lib/resty/dns/server.lua
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Original file line number Diff line number Diff line change
Expand Up @@ -27,6 +27,7 @@ local TYPE_MX = 15
local TYPE_TXT = 16
local TYPE_AAAA = 28
local TYPE_SRV = 33
local TYPE_OPT = 41
local TYPE_SPF = 99
local TYPE_ANY = 255

Expand Down Expand Up @@ -267,10 +268,10 @@ function _M.decode_request(self, req)
self.pos = self.pos + 2
local opt_ver_hi, opt_ver_lo = byte(self.buf, self.pos - 1, self.pos)
local opt_ver = lshift(opt_ver_hi, 8) + opt_ver_lo
if opt_ver ~= 0 then
self.response.header.rcode = RCODE_BADVERS
return nil, "bad EDNS0 opt version(" .. opt_ver .. ")"
end
-- if opt_ver ~= 0 then
-- self.response.header.rcode = RCODE_BADVERS
-- return nil, "bad EDNS0 opt version(" .. opt_ver .. ")"
-- end

-- parse RDLENGTH(describes RDATA)
self.pos = self.pos + 2
Expand All @@ -280,7 +281,11 @@ function _M.decode_request(self, req)
-- parse RDATA(OPTION)
-- rfc7871, 6. Option Format

local rdata = nil
if rdlen > 0 then
-- get whole rdata
rdata = strsub(self.buf, self.pos +1 , self.pos + rdlen)

-- parse OPTION-CODE
self.pos = self.pos + 2
local opt_code_hi, opt_code_lo = byte(self.buf, self.pos - 1, self.pos)
Expand Down Expand Up @@ -325,11 +330,17 @@ function _M.decode_request(self, req)
end
address = concat(ipv6, ":")
end

self.request.subnet[#self.request.subnet + 1] = {address = address,
mask = source_prefix_len,
family = opt_family}
mask = source_prefix_len,
family = opt_family}
end
self.request.additionals[#self.request.additionals + 1] = { name="",
type = opt_type,
class = udp_size,
ttl = ext_rcode,
rdlength = rdlen,
rdata = rdata }

else
ngx.log(ngx.WARN, "parse EDNS0 error. qname_len: ",
qname_len, " opt_type: ", opt_type)
Expand Down Expand Up @@ -375,7 +386,6 @@ local function _encode_4byt(x)
return char(hi_hi, hi_lo, lo_hi, lo_lo)
end


local function _encode_2byt(x)
local hi = band(rshift(x, 8), 0x00FF)
local lo = band(x, 0x00FF)
Expand Down Expand Up @@ -461,12 +471,14 @@ function _M.encode_response(self)
end

for i = 1, self.response.header.arcount do
buf = buf .. _encode_name(self.response.arsections[i].name)
buf = buf .. _encode_name(self.response.arsections[i].name)
buf = buf .. _encode_2byt(self.response.arsections[i].type)
buf = buf .. _encode_2byt(self.response.arsections[i].class)
buf = buf .. _encode_4byt(self.response.arsections[i].ttl or 0x258)
buf = buf .. _encode_2byt(self.response.arsections[i].rdlength)
buf = buf .. self.response.arsections[i].rdata
if self.response.arsections[i].rdlength > 0 then
buf = buf .. self.response.arsections[i].rdata
end
end

return buf
Expand Down Expand Up @@ -520,6 +532,17 @@ function _M.create_a_answer(self, name, ttl, ipv4)
return nil
end

function _M.replay_additional_opts(self)

for i = 1, #self.request.additionals do
local additional = self.request.additionals[i]
self.response.header.arcount = self.response.header.arcount + 1
self.response.arsections[self.response.header.arcount] = additional
end

return nil
end


function _M.create_cname_answer(self, name, ttl, cname)
if not name or #name == 0 then
Expand Down