From 1b91be49f53936429d16fb841433139a66af6262 Mon Sep 17 00:00:00 2001
From: Pieter Wuille <pieter.wuille@gmail.com>
Date: Thu, 27 Nov 2014 10:46:55 +0100
Subject: [PATCH] Report status of chain tips

---
 qa/pull-tester/rpc-tests.sh  |  1 +
 qa/rpc-tests/getchaintips.py |  7 ++++++-
 src/rpcblockchain.cpp        | 27 +++++++++++++++++++++++++++
 3 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/qa/pull-tester/rpc-tests.sh b/qa/pull-tester/rpc-tests.sh
index e01e87039..2f1e24b78 100755
--- a/qa/pull-tester/rpc-tests.sh
+++ b/qa/pull-tester/rpc-tests.sh
@@ -20,6 +20,7 @@ if [ "x${ENABLE_BITCOIND}${ENABLE_UTILS}${ENABLE_WALLET}" = "x111" ]; then
   ${BUILDDIR}/qa/rpc-tests/listtransactions.py --srcdir "${BUILDDIR}/src"
   ${BUILDDIR}/qa/rpc-tests/txn_doublespend.py --srcdir "${BUILDDIR}/src"
   ${BUILDDIR}/qa/rpc-tests/txn_doublespend.py --mineblock --srcdir "${BUILDDIR}/src"
+  ${BUILDDIR}/qa/rpc-tests/getchaintips.py --srcdir "${BUILDDIR}/src"
   #${BUILDDIR}/qa/rpc-tests/forknotify.py --srcdir "${BUILDDIR}/src"
 else
   echo "No rpc tests to run. Wallet, utils, and bitcoind must all be enabled"
diff --git a/qa/rpc-tests/getchaintips.py b/qa/rpc-tests/getchaintips.py
index dda3450eb..1e84b40e4 100755
--- a/qa/rpc-tests/getchaintips.py
+++ b/qa/rpc-tests/getchaintips.py
@@ -19,6 +19,7 @@ class GetChainTipsTest (BitcoinTestFramework):
         assert_equal (len (tips), 1)
         assert_equal (tips[0]['branchlen'], 0)
         assert_equal (tips[0]['height'], 200)
+        assert_equal (tips[0]['status'], 'active')
 
         # Split the network and build two chains of different lengths.
         self.split_network ()
@@ -31,12 +32,14 @@ class GetChainTipsTest (BitcoinTestFramework):
         shortTip = tips[0]
         assert_equal (shortTip['branchlen'], 0)
         assert_equal (shortTip['height'], 210)
+        assert_equal (tips[0]['status'], 'active')
 
         tips = self.nodes[3].getchaintips ()
         assert_equal (len (tips), 1)
         longTip = tips[0]
         assert_equal (longTip['branchlen'], 0)
         assert_equal (longTip['height'], 220)
+        assert_equal (tips[0]['status'], 'active')
 
         # Join the network halves and check that we now have two tips
         # (at least at the nodes that previously had the short chain).
@@ -47,7 +50,9 @@ class GetChainTipsTest (BitcoinTestFramework):
         assert_equal (tips[0], longTip)
 
         assert_equal (tips[1]['branchlen'], 10)
-        tips[1]['branchlen'] = 0;
+        assert_equal (tips[1]['status'], 'valid-fork')
+        tips[1]['branchlen'] = 0
+        tips[1]['status'] = 'active'
         assert_equal (tips[1], shortTip)
 
 if __name__ == '__main__':
diff --git a/src/rpcblockchain.cpp b/src/rpcblockchain.cpp
index e8b0f62a8..5c4ee691d 100644
--- a/src/rpcblockchain.cpp
+++ b/src/rpcblockchain.cpp
@@ -496,11 +496,13 @@ Value getchaintips(const Array& params, bool fHelp)
             "    \"height\": xxxx,         (numeric) height of the chain tip\n"
             "    \"hash\": \"xxxx\",         (string) block hash of the tip\n"
             "    \"branchlen\": 0          (numeric) zero for main chain\n"
+            "    \"status\": \"active\"      (string) \"active\" for the main chain\n"
             "  },\n"
             "  {\n"
             "    \"height\": xxxx,\n"
             "    \"hash\": \"xxxx\",\n"
             "    \"branchlen\": 1          (numeric) length of branch connecting the tip to the main chain\n"
+            "    \"status\": \"xxxx\"        (string) status of the chain (active, valid-fork, valid-headers, headers-only, invalid)\n"
             "  }\n"
             "]\n"
             "\nExamples:\n"
@@ -521,6 +523,9 @@ Value getchaintips(const Array& params, bool fHelp)
             setTips.erase(pprev);
     }
 
+    // Always report the currently active tip.
+    setTips.insert(chainActive.Tip());
+
     /* Construct the output array.  */
     Array res;
     BOOST_FOREACH(const CBlockIndex* block, setTips)
@@ -532,6 +537,28 @@ Value getchaintips(const Array& params, bool fHelp)
         const int branchLen = block->nHeight - chainActive.FindFork(block)->nHeight;
         obj.push_back(Pair("branchlen", branchLen));
 
+        string status;
+        if (chainActive.Contains(block)) {
+            // This block is part of the currently active chain.
+            status = "active";
+        } else if (block->nStatus & BLOCK_FAILED_MASK) {
+            // This block or one of its ancestors is invalid.
+            status = "invalid";
+        } else if (block->nChainTx == 0) {
+            // This block cannot be connected because full block data for it or one of its parents is missing.
+            status = "headers-only";
+        } else if (block->IsValid(BLOCK_VALID_SCRIPTS)) {
+            // This block is fully validated, but no longer part of the active chain. It was probably the active block once, but was reorganized.
+            status = "valid-fork";
+        } else if (block->IsValid(BLOCK_VALID_TREE)) {
+            // The headers for this block are valid, but it has not been validated. It was probably never part of the most-work chain.
+            status = "valid-headers";
+        } else {
+            // No clue.
+            status = "unknown";
+        }
+        obj.push_back(Pair("status", status));
+
         res.push_back(obj);
     }