fix digest mapping for scram auth

Author: fffonion

pgmoon/init.lua

@@ -409,6 +409,11 @@ do
             end
             if signature:match("^md5") or signature:match("^sha1") or signature:match("sha1$") then
               signature = "sha256"
+            else
+              local objects = require("resty.openssl.objects")
+              local sigid = assert(objects.txt2nid(signature))
+              local digest_nid = assert(objects.find_sigid_algs(sigid))
+              signature = assert(objects.nid2table(digest_nid).sn)
             end
             cbind_data = assert(x509_digest(pem, signature))
           end

pgmoon/init.moon

@@ -414,6 +414,11 @@ class Postgres
           -- upgrade the signature if necessary (also handle the case of s/RSA-SHA1/sha256)
           if signature\match("^md5") or signature\match("^sha1") or signature\match("sha1$")
             signature = "sha256"
+          else
+            local objects = require("resty.openssl.objects")
+            local sigid = assert objects.txt2nid(signature)
+            local digest_nid = assert objects.find_sigid_algs(sigid)
+            signature = assert objects.nid2table(digest_nid).sn
 
           assert x509_digest(pem, signature)