From: Vsevolod Stakhov <vsevolod@rspamd.com>
Date: Sat, 25 Apr 2026 18:44:16 +0000 (+0100)
Subject: [Fix] lua_scanners: emit fail symbol on nil upstream
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=13c5a71ef8606f014a236e622dbf764ca39a76a1;p=thirdparty%2Frspamd.git

[Fix] lua_scanners: emit fail symbol on nil upstream

After the upstream layer learnt to defer DNS resolution, every
scanner's :get_upstream_round_robin() may return nil while the host
is still pending (or when every backend has been marked dead). The
scanners then crashed in the scan callback on `upstream:get_addr()`,
which silently aborted the scan instead of surfacing the failure.

Add a shared lua_scanners/common.get_upstream_or_fail(task, rule,
maybe_part, reason) helper that selects an upstream and, on nil,
emits the configured *_FAIL symbol via yield_result with reason
"no upstream available (DNS pending or all dead)". Update every
scanner under lualib/lua_scanners/ to use the helper for the initial
selection, and to add an inline yield_result+return guard around the
retry-on-error sites that pick a different upstream.

Cloudmark also has a config-time preload that picks an upstream to
detect max message size; that path now logs an error and returns,
since there is no task context to report against.
---

diff --git a/lualib/lua_scanners/avast.lua b/lualib/lua_scanners/avast.lua
index 6bbb046ce7..754c6311ae 100644
--- a/lualib/lua_scanners/avast.lua
+++ b/lualib/lua_scanners/avast.lua
@@ -83,7 +83,10 @@ end
 
 local function avast_check(task, content, digest, rule, maybe_part)
   local function avast_check_uncached ()
-    local upstream = rule.upstreams:get_upstream_round_robin()
+    local upstream = common.get_upstream_or_fail(task, rule, maybe_part)
+    if not upstream then
+      return
+    end
     local addr = upstream:get_addr()
     local retransmits = rule.retransmits
     local CRLF = '\r\n'
@@ -155,6 +158,11 @@ local function avast_check(task, content, digest, rule, maybe_part)
       end
 
       upstream = rule.upstreams:get_upstream_round_robin()
+      if not upstream then
+        common.yield_result(task, rule,
+            'no upstream available for retry', 0.0, 'fail', maybe_part)
+        return
+      end
       addr = upstream:get_addr()
       tcp_opts.upstream = upstream
       tcp_opts.callback = avast_helo_cb
diff --git a/lualib/lua_scanners/clamav.lua b/lualib/lua_scanners/clamav.lua
index fc99ab0b91..5a9c339298 100644
--- a/lualib/lua_scanners/clamav.lua
+++ b/lualib/lua_scanners/clamav.lua
@@ -81,7 +81,10 @@ end
 
 local function clamav_check(task, content, digest, rule, maybe_part)
   local function clamav_check_uncached ()
-    local upstream = rule.upstreams:get_upstream_round_robin()
+    local upstream = common.get_upstream_or_fail(task, rule, maybe_part)
+    if not upstream then
+      return
+    end
     local addr = upstream:get_addr()
     local retransmits = rule.retransmits
     local header = rspamd_util.pack("c9 c1 >I4", "zINSTREAM", "\0",
@@ -98,6 +101,11 @@ local function clamav_check(task, content, digest, rule, maybe_part)
 
           -- Select a different upstream!
           upstream = rule.upstreams:get_upstream_round_robin()
+          if not upstream then
+            common.yield_result(task, rule,
+                'no upstream available for retry', 0.0, 'fail', maybe_part)
+            return
+          end
           addr = upstream:get_addr()
 
           lua_util.debugm(rule.name, task, '%s: error: %s; retry IP: %s; retries left: %s',
diff --git a/lualib/lua_scanners/cloudmark.lua b/lualib/lua_scanners/cloudmark.lua
index 12a60abf1d..498b1e9b04 100644
--- a/lualib/lua_scanners/cloudmark.lua
+++ b/lualib/lua_scanners/cloudmark.lua
@@ -55,6 +55,11 @@ end
 -- Detect cloudmark max size
 local function cloudmark_preload(rule, cfg, ev_base, _)
   local upstream = rule.upstreams:get_upstream_round_robin()
+  if not upstream then
+    rspamd_logger.errx(ev_base or rspamd_config,
+        'cloudmark preload: no upstream available, will retry on next scan')
+    return
+  end
   local addr = upstream:get_addr()
   local function max_message_size_cb(http_err, code, body, _)
     if http_err then
@@ -258,7 +263,10 @@ end
 
 local function cloudmark_check(task, content, digest, rule, maybe_part)
   local function cloudmark_check_uncached()
-    local upstream = rule.upstreams:get_upstream_round_robin()
+    local upstream = common.get_upstream_or_fail(task, rule, maybe_part)
+    if not upstream then
+      return
+    end
     local addr = upstream:get_addr()
     local retransmits = rule.retransmits
 
@@ -336,6 +344,11 @@ local function cloudmark_check(task, content, digest, rule, maybe_part)
 
           -- Select a different upstream!
           upstream = rule.upstreams:get_upstream_round_robin()
+          if not upstream then
+            common.yield_result(task, rule,
+                'no upstream available for retry', 0.0, 'fail', maybe_part)
+            return
+          end
           addr = upstream:get_addr()
           url = cloudmark_url(rule, addr)
 
diff --git a/lualib/lua_scanners/common.lua b/lualib/lua_scanners/common.lua
index f5e760eec2..2cad0a7895 100644
--- a/lualib/lua_scanners/common.lua
+++ b/lualib/lua_scanners/common.lua
@@ -509,6 +509,26 @@ local function check_metric_results(task, rule)
   end
 end
 
+--[[
+Pick a round-robin upstream from `rule.upstreams` and emit `symbol_fail` if
+none is currently usable (e.g. all hostnames are still pending DNS resolution
+or every backend has been marked dead). Returns the upstream on success or
+nil on failure — in the nil case `symbol_fail` has already been recorded, so
+the caller should just return.
+--]]
+local function get_upstream_or_fail(task, rule, maybe_part, reason)
+  local upstream = rule.upstreams and rule.upstreams:get_upstream_round_robin()
+
+  if not upstream then
+    yield_result(task, rule,
+        reason or 'no upstream available (DNS pending or all dead)',
+        0.0, 'fail', maybe_part)
+    return nil
+  end
+
+  return upstream
+end
+
 exports.log_clean = log_clean
 exports.yield_result = yield_result
 exports.match_patterns = match_patterns
@@ -517,6 +537,7 @@ exports.save_cache = save_cache
 exports.create_regex_table = create_regex_table
 exports.check_parts_match = check_parts_match
 exports.check_metric_results = check_metric_results
+exports.get_upstream_or_fail = get_upstream_or_fail
 
 setmetatable(exports, {
   __call = function(t, override)
diff --git a/lualib/lua_scanners/dcc.lua b/lualib/lua_scanners/dcc.lua
index ed60ae486d..642889d730 100644
--- a/lualib/lua_scanners/dcc.lua
+++ b/lualib/lua_scanners/dcc.lua
@@ -85,7 +85,10 @@ local function dcc_config(opts)
 end
 
 local function dcc_check(task, content, digest, rule)
-  local upstream = rule.upstreams:get_upstream_round_robin()
+  local upstream = common.get_upstream_or_fail(task, rule, nil)
+  if not upstream then
+    return
+  end
   local addr = upstream:get_addr()
   local retransmits = rule.retransmits
   local client = rule.client
@@ -144,6 +147,11 @@ local function dcc_check(task, content, digest, rule)
 
         -- Select a different upstream!
         upstream = rule.upstreams:get_upstream_round_robin()
+        if not upstream then
+          common.yield_result(task, rule,
+              'no upstream available for retry', 0.0, 'fail')
+          return
+        end
         addr = upstream:get_addr()
 
         lua_util.debugm(rule.name, task, '%s: error: %s; retry IP: %s; retries left: %s',
diff --git a/lualib/lua_scanners/expurgate.lua b/lualib/lua_scanners/expurgate.lua
index 8405374a0a..27f6dc9d6b 100644
--- a/lualib/lua_scanners/expurgate.lua
+++ b/lualib/lua_scanners/expurgate.lua
@@ -145,7 +145,10 @@ local function expurgate_check(task, content, digest, rule, maybe_part)
       return url
     end
 
-    local upstream = rule.upstreams:get_upstream_round_robin()
+    local upstream = common.get_upstream_or_fail(task, rule, maybe_part)
+    if not upstream then
+      return
+    end
     local addr = upstream:get_addr()
     local retransmits = rule.retransmits
 
@@ -205,6 +208,11 @@ local function expurgate_check(task, content, digest, rule, maybe_part)
 
           -- Select a different upstream!
           upstream = rule.upstreams:get_upstream_round_robin()
+          if not upstream then
+            common.yield_result(task, rule,
+                'no upstream available for retry', 0.0, 'fail', maybe_part)
+            return
+          end
           addr = upstream:get_addr()
           url = expurgate_spamd_url(addr)
 
diff --git a/lualib/lua_scanners/fprot.lua b/lualib/lua_scanners/fprot.lua
index 5a469c3270..790bbbbf48 100644
--- a/lualib/lua_scanners/fprot.lua
+++ b/lualib/lua_scanners/fprot.lua
@@ -80,7 +80,10 @@ end
 
 local function fprot_check(task, content, digest, rule, maybe_part)
   local function fprot_check_uncached ()
-    local upstream = rule.upstreams:get_upstream_round_robin()
+    local upstream = common.get_upstream_or_fail(task, rule, maybe_part)
+    if not upstream then
+      return
+    end
     local addr = upstream:get_addr()
     local retransmits = rule.retransmits
     local scan_id = task:get_queue_id()
@@ -100,6 +103,11 @@ local function fprot_check(task, content, digest, rule, maybe_part)
 
           -- Select a different upstream!
           upstream = rule.upstreams:get_upstream_round_robin()
+          if not upstream then
+            common.yield_result(task, rule,
+                'no upstream available for retry', 0.0, 'fail', maybe_part)
+            return
+          end
           addr = upstream:get_addr()
 
           lua_util.debugm(rule.name, task, '%s: error: %s; retry IP: %s; retries left: %s',
diff --git a/lualib/lua_scanners/icap.lua b/lualib/lua_scanners/icap.lua
index 5328587939..dc10db26c0 100644
--- a/lualib/lua_scanners/icap.lua
+++ b/lualib/lua_scanners/icap.lua
@@ -166,7 +166,10 @@ end
 
 local function icap_check(task, content, digest, rule, maybe_part)
   local function icap_check_uncached ()
-    local upstream = rule.upstreams:get_upstream_round_robin()
+    local upstream = common.get_upstream_or_fail(task, rule, maybe_part)
+    if not upstream then
+      return
+    end
     local addr = upstream:get_addr()
     local retransmits = rule.retransmits
     local http_headers = {}
@@ -218,6 +221,11 @@ local function icap_check(task, content, digest, rule, maybe_part)
 
           -- Select a different upstream!
           upstream = rule.upstreams:get_upstream_round_robin()
+          if not upstream then
+            common.yield_result(task, rule, 'no upstream available for retry', 0.0,
+                'fail', maybe_part)
+            return
+          end
           addr = upstream:get_addr()
 
           lua_util.debugm(rule.name, task, '%s: retry IP: %s:%s',
@@ -239,7 +247,7 @@ local function icap_check(task, content, digest, rule, maybe_part)
         end
       end
 
-      local function get_req_headers()                
+      local function get_req_headers()
         local in_client_ip = task:get_from_ip()
         local in_client_ip_str = in_client_ip:to_string()
         local req_hlen = 2
diff --git a/lualib/lua_scanners/kaspersky_av.lua b/lualib/lua_scanners/kaspersky_av.lua
index 6ae6b620e3..a90c8b3499 100644
--- a/lualib/lua_scanners/kaspersky_av.lua
+++ b/lualib/lua_scanners/kaspersky_av.lua
@@ -81,7 +81,10 @@ end
 
 local function kaspersky_check(task, content, digest, rule, maybe_part)
   local function kaspersky_check_uncached ()
-    local upstream = rule.upstreams:get_upstream_round_robin()
+    local upstream = common.get_upstream_or_fail(task, rule, maybe_part)
+    if not upstream then
+      return
+    end
     local addr = upstream:get_addr()
     local retransmits = rule.retransmits
     local fname = string.format('%s/%s.tmp',
@@ -117,6 +120,11 @@ local function kaspersky_check(task, content, digest, rule, maybe_part)
 
           -- Select a different upstream!
           upstream = rule.upstreams:get_upstream_round_robin()
+          if not upstream then
+            common.yield_result(task, rule,
+                'no upstream available for retry', 0.0, 'fail', maybe_part)
+            return
+          end
           addr = upstream:get_addr()
 
           lua_util.debugm(rule.name, task, '%s: error: %s; retry IP: %s; retries left: %s',
diff --git a/lualib/lua_scanners/kaspersky_se.lua b/lualib/lua_scanners/kaspersky_se.lua
index 7bef586e14..d5fcff2561 100644
--- a/lualib/lua_scanners/kaspersky_se.lua
+++ b/lualib/lua_scanners/kaspersky_se.lua
@@ -110,7 +110,10 @@ local function kaspersky_se_check(task, content, digest, rule, maybe_part)
       return url
     end
 
-    local upstream = rule.upstreams:get_upstream_round_robin()
+    local upstream = common.get_upstream_or_fail(task, rule, maybe_part)
+    if not upstream then
+      return
+    end
     local addr = upstream:get_addr()
     local retransmits = rule.retransmits
 
@@ -189,6 +192,11 @@ local function kaspersky_se_check(task, content, digest, rule, maybe_part)
 
           -- Select a different upstream!
           upstream = rule.upstreams:get_upstream_round_robin()
+          if not upstream then
+            common.yield_result(task, rule,
+                'no upstream available for retry', 0.0, 'fail', maybe_part)
+            return
+          end
           addr = upstream:get_addr()
           url = make_url(addr)
 
diff --git a/lualib/lua_scanners/oletools.lua b/lualib/lua_scanners/oletools.lua
index 378e094675..2ccadca6c6 100644
--- a/lualib/lua_scanners/oletools.lua
+++ b/lualib/lua_scanners/oletools.lua
@@ -89,7 +89,10 @@ end
 
 local function oletools_check(task, content, digest, rule, maybe_part)
   local function oletools_check_uncached ()
-    local upstream = rule.upstreams:get_upstream_round_robin()
+    local upstream = common.get_upstream_or_fail(task, rule, maybe_part)
+    if not upstream then
+      return
+    end
     local addr = upstream:get_addr()
     local retransmits = rule.retransmits
     local protocol = 'OLEFY/1.0\nMethod: oletools\nRspamd-ID: ' .. task:get_uid() .. '\n\n'
@@ -106,6 +109,11 @@ local function oletools_check(task, content, digest, rule, maybe_part)
 
           -- Select a different upstream!
           upstream = rule.upstreams:get_upstream_round_robin()
+          if not upstream then
+            common.yield_result(task, rule,
+                'no upstream available for retry', 0.0, 'fail', maybe_part)
+            return
+          end
           addr = upstream:get_addr()
 
           lua_util.debugm(rule.name, task, '%s: error: %s; retry IP: %s; retries left: %s',
diff --git a/lualib/lua_scanners/pyzor.lua b/lualib/lua_scanners/pyzor.lua
index 75c1b4a157..a00600ba85 100644
--- a/lualib/lua_scanners/pyzor.lua
+++ b/lualib/lua_scanners/pyzor.lua
@@ -77,7 +77,10 @@ end
 
 local function pyzor_check(task, content, digest, rule)
   local function pyzor_check_uncached ()
-    local upstream = rule.upstreams:get_upstream_round_robin()
+    local upstream = common.get_upstream_or_fail(task, rule, nil)
+    if not upstream then
+      return
+    end
     local addr = upstream:get_addr()
     local retransmits = rule.retransmits
 
@@ -92,6 +95,11 @@ local function pyzor_check(task, content, digest, rule)
 
           -- Select a different upstream!
           upstream = rule.upstreams:get_upstream_round_robin()
+          if not upstream then
+            common.yield_result(task, rule,
+                'no upstream available for retry', 0.0, 'fail')
+            return
+          end
           addr = upstream:get_addr()
 
           lua_util.debugm(N, task, '%s: retry IP: %s:%s err: %s',
diff --git a/lualib/lua_scanners/razor.lua b/lualib/lua_scanners/razor.lua
index fcc0a8e3a3..5c91bb8b7e 100644
--- a/lualib/lua_scanners/razor.lua
+++ b/lualib/lua_scanners/razor.lua
@@ -82,7 +82,10 @@ end
 
 local function razor_check(task, content, digest, rule)
   local function razor_check_uncached ()
-    local upstream = rule.upstreams:get_upstream_round_robin()
+    local upstream = common.get_upstream_or_fail(task, rule, nil)
+    if not upstream then
+      return
+    end
     local addr = upstream:get_addr()
     local retransmits = rule.retransmits
 
@@ -99,6 +102,11 @@ local function razor_check(task, content, digest, rule)
 
           -- Select a different upstream!
           upstream = rule.upstreams:get_upstream_round_robin()
+          if not upstream then
+            common.yield_result(task, rule,
+                'no upstream available for retry', 0.0, 'fail')
+            return
+          end
           addr = upstream:get_addr()
 
           lua_util.debugm(rule.name, task, '%s: retry IP: %s:%s',
diff --git a/lualib/lua_scanners/savapi.lua b/lualib/lua_scanners/savapi.lua
index 293b8f3b54..f5602815df 100644
--- a/lualib/lua_scanners/savapi.lua
+++ b/lualib/lua_scanners/savapi.lua
@@ -83,7 +83,10 @@ end
 
 local function savapi_check(task, content, digest, rule)
   local function savapi_check_uncached ()
-    local upstream = rule.upstreams:get_upstream_round_robin()
+    local upstream = common.get_upstream_or_fail(task, rule, nil)
+    if not upstream then
+      return
+    end
     local addr = upstream:get_addr()
     local retransmits = rule.retransmits
     local fname = string.format('%s/%s.tmp',
@@ -205,6 +208,11 @@ local function savapi_check(task, content, digest, rule)
 
           -- Select a different upstream!
           upstream = rule.upstreams:get_upstream_round_robin()
+          if not upstream then
+            common.yield_result(task, rule,
+                'no upstream available for retry', 0.0, 'fail')
+            return
+          end
           addr = upstream:get_addr()
 
           lua_util.debugm(rule.name, task, '%s: error: %s; retry IP: %s; retries left: %s',
diff --git a/lualib/lua_scanners/sophos.lua b/lualib/lua_scanners/sophos.lua
index d9b64f1a80..6153a5606d 100644
--- a/lualib/lua_scanners/sophos.lua
+++ b/lualib/lua_scanners/sophos.lua
@@ -80,7 +80,10 @@ end
 
 local function sophos_check(task, content, digest, rule, maybe_part)
   local function sophos_check_uncached ()
-    local upstream = rule.upstreams:get_upstream_round_robin()
+    local upstream = common.get_upstream_or_fail(task, rule, maybe_part)
+    if not upstream then
+      return
+    end
     local addr = upstream:get_addr()
     local retransmits = rule.retransmits
     local protocol = 'SSSP/1.0\n'
@@ -97,6 +100,11 @@ local function sophos_check(task, content, digest, rule, maybe_part)
 
           -- Select a different upstream!
           upstream = rule.upstreams:get_upstream_round_robin()
+          if not upstream then
+            common.yield_result(task, rule,
+                'no upstream available for retry', 0.0, 'fail', maybe_part)
+            return
+          end
           addr = upstream:get_addr()
 
           lua_util.debugm(rule.name, task, '%s: error: %s; retry IP: %s; retries left: %s',
diff --git a/lualib/lua_scanners/spamassassin.lua b/lualib/lua_scanners/spamassassin.lua
index f425924d5f..cb3fc8b09d 100644
--- a/lualib/lua_scanners/spamassassin.lua
+++ b/lualib/lua_scanners/spamassassin.lua
@@ -86,7 +86,10 @@ end
 
 local function spamassassin_check(task, content, digest, rule)
   local function spamassassin_check_uncached ()
-    local upstream = rule.upstreams:get_upstream_round_robin()
+    local upstream = common.get_upstream_or_fail(task, rule, nil)
+    if not upstream then
+      return
+    end
     local addr = upstream:get_addr()
     local retransmits = rule.retransmits
 
@@ -114,6 +117,11 @@ local function spamassassin_check(task, content, digest, rule)
 
           -- Select a different upstream!
           upstream = rule.upstreams:get_upstream_round_robin()
+          if not upstream then
+            common.yield_result(task, rule,
+                'no upstream available for retry', 0.0, 'fail')
+            return
+          end
           addr = upstream:get_addr()
 
           lua_util.debugm(rule.N, task, '%s: retry IP: %s:%s',
diff --git a/lualib/lua_scanners/vadesecure.lua b/lualib/lua_scanners/vadesecure.lua
index 826573a890..6862ab7ede 100644
--- a/lualib/lua_scanners/vadesecure.lua
+++ b/lualib/lua_scanners/vadesecure.lua
@@ -167,7 +167,10 @@ local function vade_check(task, content, digest, rule, maybe_part)
       return url
     end
 
-    local upstream = rule.upstreams:get_upstream_round_robin()
+    local upstream = common.get_upstream_or_fail(task, rule, maybe_part)
+    if not upstream then
+      return
+    end
     local addr = upstream:get_addr()
     local retransmits = rule.retransmits
 
@@ -241,6 +244,11 @@ local function vade_check(task, content, digest, rule, maybe_part)
 
           -- Select a different upstream!
           upstream = rule.upstreams:get_upstream_round_robin()
+          if not upstream then
+            common.yield_result(task, rule,
+                'no upstream available for retry', 0.0, 'fail', maybe_part)
+            return
+          end
           addr = upstream:get_addr()
           url = vade_url(addr)