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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-06 00:55:53 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-06 00:55:53 +0000
commit3d0386f27ca66379acf50199e1d1298386eeeeb8 (patch)
treef87bd4a126b3a843858eb447e8fd5893c3ee3882 /modules/renumber/renumber.lua
parentInitial commit. (diff)
downloadknot-resolver-upstream.tar.xz
knot-resolver-upstream.zip
Adding upstream version 3.2.1.upstream/3.2.1upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r--modules/renumber/renumber.lua126
1 files changed, 126 insertions, 0 deletions
diff --git a/modules/renumber/renumber.lua b/modules/renumber/renumber.lua
new file mode 100644
index 0000000..ca77b94
--- /dev/null
+++ b/modules/renumber/renumber.lua
@@ -0,0 +1,126 @@
+-- Module interface
+local ffi = require('ffi')
+local prefixes = {}
+
+-- Create subnet prefix rule
+local function matchprefix(subnet, addr)
+ local target = kres.str2ip(addr)
+ if target == nil then error('[renumber] invalid address: '..addr) end
+ local addrtype = string.find(addr, ':', 1, true) and kres.type.AAAA or kres.type.A
+ local subnet_cd = ffi.new('char[16]')
+ local bitlen = ffi.C.kr_straddr_subnet(subnet_cd, subnet)
+ -- Mask unspecified, renumber whole IP
+ if bitlen == 0 then
+ bitlen = #target * 8
+ end
+ return {subnet_cd, bitlen, target, addrtype}
+end
+
+-- Create name match rule
+local function matchname(name, addr)
+ local target = kres.str2ip(addr)
+ if target == nil then error('[renumber] invalid address: '..addr) end
+ local owner = todname(name)
+ if not name then error('[renumber] invalid name: '..name) end
+ local addrtype = string.find(addr, ':', 1, true) and kres.type.AAAA or kres.type.A
+ return {owner, nil, target, addrtype}
+end
+
+-- Add subnet prefix rewrite rule
+local function add_prefix(subnet, addr)
+ table.insert(prefixes, matchprefix(subnet, addr))
+end
+
+-- Match IP against given subnet or record owner
+local function match_subnet(subnet, bitlen, addrtype, rr)
+ local addr = rr.rdata
+ return addrtype == rr.type and
+ ((bitlen and (#addr >= bitlen / 8) and (ffi.C.kr_bitcmp(subnet, addr, bitlen) == 0)) or subnet == rr.owner)
+end
+
+-- Renumber address record
+local addr_buf = ffi.new('char[16]')
+local function renumber_record(tbl, rr)
+ for i = 1, #tbl do
+ local prefix = tbl[i]
+ -- Match record type to address family and record address to given subnet
+ -- If provided, compare record owner to prefix name
+ if match_subnet(prefix[1], prefix[2], prefix[4], rr) then
+ -- Replace part or whole address
+ local to_copy = prefix[2] or (#prefix[3] * 8)
+ local chunks = to_copy / 8
+ local rdlen = #rr.rdata
+ if rdlen < chunks then return rr end -- Address length mismatch
+ ffi.copy(addr_buf, rr.rdata, rdlen)
+ ffi.copy(addr_buf, prefix[3], chunks) -- Rewrite prefix
+ rr.rdata = ffi.string(addr_buf, rdlen)
+ return rr
+ end
+ end
+ return nil
+end
+
+-- Renumber addresses based on config
+local function rule()
+ return function (state, req)
+ if state == kres.FAIL then return state end
+ req = kres.request_t(req)
+ local pkt = kres.pkt_t(req.answer)
+ -- Only successful answers
+ local records = pkt:section(kres.section.ANSWER)
+ local ancount = #records
+ if ancount == 0 then return state end
+ -- Find renumber candidates
+ local changed = false
+ for i = 1, ancount do
+ local rr = records[i]
+ if rr.type == kres.type.A or rr.type == kres.type.AAAA then
+ local new_rr = renumber_record(prefixes, rr)
+ if new_rr ~= nil then
+ records[i] = new_rr
+ changed = true
+ end
+ end
+ end
+ -- If not rewritten, chain action
+ if not changed then return end
+ -- Replace section if renumbering
+ local qname = pkt:qname()
+ local qclass = pkt:qclass()
+ local qtype = pkt:qtype()
+ pkt:recycle()
+ pkt:question(qname, qclass, qtype)
+ for i = 1, ancount do
+ local rr = records[i]
+ -- Strip signatures as rewritten data cannot be validated
+ if rr.type ~= kres.type.RRSIG then
+ pkt:put(rr.owner, rr.ttl, rr.class, rr.type, rr.rdata)
+ end
+ end
+ return state
+ end
+end
+
+-- Export module interface
+local M = {
+ prefix = matchprefix,
+ name = matchname,
+ rule = rule,
+ match_subnet = match_subnet,
+}
+
+-- Config
+function M.config (conf)
+ if conf == nil then return end
+ if type(conf) ~= 'table' or type(conf[1]) ~= 'table' then
+ error('[renumber] expected { {prefix, target}, ... }')
+ end
+ for i = 1, #conf do add_prefix(conf[i][1], conf[1][2]) end
+end
+
+-- Layers
+M.layer = {
+ finish = rule(),
+}
+
+return M