Software /
code /
prosody
File
net/resolvers/service.lua @ 13120:be4058bb5a7e
util.startup: Record current version in a metric
Useful to have this info available when juggling metrics, e.g. to
see if things changed between versions.
author | Kim Alvefur <zash@zash.se> |
---|---|
date | Wed, 31 May 2023 01:14:59 +0200 |
parent | 12974:ba409c67353b |
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local adns = require "prosody.net.adns"; local basic = require "prosody.net.resolvers.basic"; local inet_pton = require "prosody.util.net".pton; local idna_to_ascii = require "prosody.util.encodings".idna.to_ascii; local methods = {}; local resolver_mt = { __index = methods }; local function new_target_selector(rrset) local rr_count = rrset and #rrset; if not rr_count or rr_count == 0 then rrset = nil; else table.sort(rrset, function (a, b) return a.srv.priority < b.srv.priority end); end local rrset_pos = 1; local priority_bucket, bucket_total_weight, bucket_len, bucket_used; return function () if not rrset then return; end if not priority_bucket or bucket_used >= bucket_len then if rrset_pos > rr_count then return; end -- Used up all records -- Going to start on a new priority now. Gather up all the next -- records with the same priority and add them to priority_bucket priority_bucket, bucket_total_weight, bucket_len, bucket_used = {}, 0, 0, 0; local current_priority; repeat local curr_record = rrset[rrset_pos].srv; if not current_priority then current_priority = curr_record.priority; elseif current_priority ~= curr_record.priority then break; end table.insert(priority_bucket, curr_record); bucket_total_weight = bucket_total_weight + curr_record.weight; bucket_len = bucket_len + 1; rrset_pos = rrset_pos + 1; until rrset_pos > rr_count; end bucket_used = bucket_used + 1; local n, running_total = math.random(0, bucket_total_weight), 0; local target_record; for i = 1, bucket_len do local candidate = priority_bucket[i]; if candidate then running_total = running_total + candidate.weight; if running_total >= n then target_record = candidate; bucket_total_weight = bucket_total_weight - candidate.weight; priority_bucket[i] = nil; break; end end end return target_record; end; end -- Find the next target to connect to, and -- pass it to cb() function methods:next(cb) if self.resolver or self._get_next_target then if not self.resolver then -- Do we have a basic resolver currently? -- We don't, so fetch a new SRV target, create a new basic resolver for it local next_srv_target = self._get_next_target and self._get_next_target(); if not next_srv_target then -- No more SRV targets left cb(nil); return; end -- Create a new basic resolver for this SRV target self.resolver = basic.new(next_srv_target.target, next_srv_target.port, self.conn_type, self.extra); end -- Look up the next (basic) target from the current target's resolver self.resolver:next(function (...) if self.resolver then self.last_error = self.resolver.last_error; end if ... == nil then self.resolver = nil; self:next(cb); else cb(...); end end); return; elseif self.in_progress then cb(nil); return; end if not self.hostname then self.last_error = "hostname failed IDNA"; cb(nil); return; end self.in_progress = true; local function ready() self:next(cb); end -- Resolve DNS to target list local dns_resolver = adns.resolver(); dns_resolver:lookup(function (answer, err) if not answer and not err then -- net.adns returns nil if there are zero records or nxdomain answer = {}; end if answer then if answer.bogus then self.last_error = "Validation error in SRV lookup"; ready(); return; elseif not answer.secure then if self.extra then -- Insecure results, so no DANE self.extra.use_dane = false; end end if self.extra then self.extra.srv_secure = answer.secure; end if #answer == 0 then if self.extra and self.extra.default_port then self.resolver = basic.new(self.hostname, self.extra.default_port, self.conn_type, self.extra); else self.last_error = "zero SRV records found"; end ready(); return; end if #answer == 1 and answer[1].srv.target == "." then -- No service here self.last_error = "service explicitly unavailable"; ready(); return; end self._get_next_target = new_target_selector(answer); else self.last_error = err; end ready(); end, "_" .. self.service .. "._" .. self.conn_type .. "." .. self.hostname, "SRV", "IN"); end local function new(hostname, service, conn_type, extra) local is_ip = inet_pton(hostname); if not is_ip and hostname:sub(1,1) == '[' then is_ip = inet_pton(hostname:sub(2,-2)); end if is_ip and extra and extra.default_port then return basic.new(hostname, extra.default_port, conn_type, extra); end return setmetatable({ hostname = idna_to_ascii(hostname); service = service; conn_type = conn_type or "tcp"; extra = extra; }, resolver_mt); end return { new = new; };