Merge pull request #3671 from moonming/randomseed-bugfix

bugfix: fixed duplicated seeds.

rootfs/etc/nginx/lua/lua_ingress.lua

@@ -2,9 +2,32 @@ local _M = {}
 
 local seeds = {}
 local original_randomseed = math.randomseed
+
+local function get_seed_from_urandom()
+  local seed
+  local frandom, err = io.open("/dev/urandom", "rb")
+  if not frandom then
+    ngx.log(ngx.WARN, 'failed to open /dev/urandom: ', err)
+    return nil
+  end
+
+  local str = frandom:read(4)
+  frandom:close()
+  if not str then
+    ngx.log(ngx.WARN, 'failed to read data from /dev/urandom')
+    return nil
+  end
+
+  seed = 0
+  for i = 1, 4 do
+      seed = 256 * seed + str:byte(i)
+  end
+
+  return seed
+end
+
 math.randomseed = function(seed)
   local pid = ngx.worker.pid()
-
   if seeds[pid] then
     ngx.log(ngx.WARN,
       string.format("ignoring math.randomseed(%d) since PRNG is already seeded for worker %d", seed, pid))
@@ -16,7 +39,12 @@ math.randomseed = function(seed)
 end
 
 local function randomseed()
-  math.randomseed(ngx.time() + ngx.worker.pid())
+  local seed = get_seed_from_urandom()
+  if not seed then
+    ngx.log(ngx.WARN, 'failed to get seed from urandom')
+    seed = ngx.now() * 1000 + ngx.worker.pid()
+  end
+  math.randomseed(seed)
 end
 
 function _M.init_worker()