From 25e548af2e74bbff88cbc634de95d4bb17f11248 Mon Sep 17 00:00:00 2001
From: moneroexamples <moneroexamples@tuta.io>
Date: Tue, 22 Nov 2016 10:43:08 +0800
Subject: [PATCH] fixed checking outputs with two public keys in tx extra

---
 src/page.h | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 51 insertions(+), 2 deletions(-)

diff --git a/src/page.h b/src/page.h
index dff2d18..15d5c2d 100644
--- a/src/page.h
+++ b/src/page.h
@@ -228,6 +228,52 @@ namespace xmreg {
 
              return ss.str();
         }
+
+
+        // based on
+        // crypto::public_key wallet2::get_tx_pub_key_from_received_outs(const tools::wallet2::transfer_details &td) const
+        public_key
+        get_tx_pub_key_from_received_outs(const transaction &tx) const
+        {
+            std::vector<tx_extra_field> tx_extra_fields;
+
+            if(!parse_tx_extra(tx.extra, tx_extra_fields))
+            {
+                // Extra may only be partially parsed, it's OK if tx_extra_fields contains public key
+            }
+
+            // Due to a previous bug, there might be more than one tx pubkey in extra, one being
+            // the result of a previously discarded signature.
+            // For speed, since scanning for outputs is a slow process, we check whether extra
+            // contains more than one pubkey. If not, the first one is returned. If yes, they're
+            // checked for whether they yield at least one output
+            tx_extra_pub_key pub_key_field;
+
+            if (!find_tx_extra_field_by_type(tx_extra_fields, pub_key_field, 0))
+            {
+                return null_pkey;
+            }
+
+            public_key tx_pub_key = pub_key_field.pub_key;
+
+            bool two_found = find_tx_extra_field_by_type(tx_extra_fields, pub_key_field, 1);
+
+            if (!two_found)
+            {
+                // easy case, just one found
+                return tx_pub_key;
+            }
+            else
+            {
+                // just return second one if there are two.
+                // this does not require private view key, as
+                // its not needed for my use case.
+                return pub_key_field.pub_key;
+            }
+
+            return null_pkey;
+        }
+
     };
 
     class page {
@@ -3322,8 +3368,11 @@ namespace xmreg {
             // get tx hash
             txd.hash = get_transaction_hash(tx);
 
-            // get tx public key
-            txd.pk = get_tx_pub_key_from_extra(tx);
+            // get tx public key from extra
+            // this check if there are two public keys
+            // due to previous bug with sining txs:
+            // https://github.com/monero-project/monero/pull/1358/commits/7abfc5474c0f86e16c405f154570310468b635c2
+            txd.pk = txd.get_tx_pub_key_from_received_outs(tx);
 
             // sum xmr in inputs and ouputs in the given tx
             txd.xmr_inputs  = sum_money_in_inputs(tx);