[Fix] Reject invalid bh for DKIM signatures earlier

src/libserver/dkim.c

@@ -2196,6 +2196,14 @@ rspamd_dkim_check (rspamd_dkim_context_t *ctx,
 					}
 				}
 			}
+			else {
+				msg_debug_dkim (
+						"bh value mismatch: %*xs versus %*xs",
+						dlen, ctx->bh,
+						dlen, cached_bh->digest_normal);
+
+				return DKIM_REJECT;
+			}
 		}
 
 		if (cpy_ctx) {