From ded2e51e60325a0e817362c6df0c341bb00d4b0e Mon Sep 17 00:00:00 2001
From: Vsevolod Stakhov <vsevolod@rspamd.com>
Date: Sat, 22 Oct 2022 13:00:21 +0100
Subject: [PATCH] [CritFix] Restore compatibility with the integrations and
 headers alterations

---
 lualib/lua_mime.lua                | 15 ++++++++++++++-
 src/plugins/lua/milter_headers.lua |  3 ++-
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/lualib/lua_mime.lua b/lualib/lua_mime.lua
index 1087b7fd5..9dff5cfed 100644
--- a/lualib/lua_mime.lua
+++ b/lualib/lua_mime.lua
@@ -515,8 +515,11 @@ end
 --[[[
 -- @function lua_mime.modify_headers(task, {add = {hname = {value = 'value', order = 1}}, remove = {hname = {1,2}}})
 -- Adds/removes headers both internal and in the milter reply
+-- Mode defines to be compatible with Rspamd <=3.2 and is the default (equal to 'compat')
 --]]
-exports.modify_headers = function(task, hdr_alterations)
+exports.modify_headers = function(task, hdr_alterations, mode)
+  -- Assume default mode compatibility
+  if not mode then mode = 'compat' end
   local add = hdr_alterations.add or {}
   local remove = hdr_alterations.remove or {}
 
@@ -550,6 +553,11 @@ exports.modify_headers = function(task, hdr_alterations)
     else
       logger.errx(task, 'invalid modification of header: %s', hdr)
     end
+
+    if mode == 'compat' and #add_headers[hname] == 1 then
+      -- Switch to the compatibility mode
+      add_headers[hname] = add_headers[hname][1]
+    end
   end
   if hdr_alterations.order then
     -- Get headers alterations ordered
@@ -580,6 +588,11 @@ exports.modify_headers = function(task, hdr_alterations)
     end
   end
 
+  if mode == 'compat' then
+    -- Clear empty alterations in the compat mode
+    if not next(add_headers) then add_headers = nil end
+    if not next(hdr_alterations.remove) then hdr_alterations.remove = nil end
+  end
   task:set_milter_reply({
     add_headers = add_headers,
     remove_headers = hdr_alterations.remove
diff --git a/src/plugins/lua/milter_headers.lua b/src/plugins/lua/milter_headers.lua
index 913b71f54..a8be5ef37 100644
--- a/src/plugins/lua/milter_headers.lua
+++ b/src/plugins/lua/milter_headers.lua
@@ -39,6 +39,7 @@ local settings = {
   skip_all = false,
   local_headers = {},
   authenticated_headers = {},
+  headers_modify_mode = 'compat', -- To avoid compatibility issues on upgrade
   default_headers_order = nil, -- Insert at the end (set 1 to insert just after the first received)
   routines = {
     ['remove-headers'] = {
@@ -572,7 +573,7 @@ local function milter_headers(task)
     lua_mime.modify_headers(task, {
       add = add,
       remove = remove
-    })
+    }, settings.headers_modify_mode)
   end
 end
 
-- 
2.39.5