Merge #9853: Fix error codes from various RPCs

adaa281 Update release notes to include RPC error code changes. (John Newbery)
338bf06 Add commenting around JSON error codes (John Newbery)
dab804c Return correct error codes in fundrawtransaction(). (John Newbery)
a012087 Return correct error codes in setban(). (John Newbery)
960bc7f Return correct error codes in removeprunedfunds(). (John Newbery)
c119096 Return correct error codes in blockchain.cpp. (John Newbery)
6d07c62 Return correct error codes in bumpfee(). (John Newbery)

Tree-SHA512: 4bb39ad221cd8c83d98ac5d7ad642f3a8c265522720dc86b2eebc70e74439a85b06d6ddcd6a874e879d986511de3ab0878bb7fe58b50cb0546b78913632ea809

3 files changed, 19 insertions, 8 deletions

diff --git a/src/rpc/blockchain.cpp b/src/rpc/blockchain.cpp
index f38b8f88aa..96254a8cb9 100644
--- a/src/rpc/blockchain.cpp
+++ b/src/rpc/blockchain.cpp
@@ -744,10 +744,15 @@ UniValue getblock(const JSONRPCRequest& request)
     CBlockIndex* pblockindex = mapBlockIndex[hash];
 
     if (fHavePruned && !(pblockindex->nStatus & BLOCK_HAVE_DATA) && pblockindex->nTx > 0)
-        throw JSONRPCError(RPC_INTERNAL_ERROR, "Block not available (pruned data)");
+        throw JSONRPCError(RPC_MISC_ERROR, "Block not available (pruned data)");
 
-    if(!ReadBlockFromDisk(block, pblockindex, Params().GetConsensus()))
-        throw JSONRPCError(RPC_INTERNAL_ERROR, "Can't read block from disk");
+    if (!ReadBlockFromDisk(block, pblockindex, Params().GetConsensus()))
+        // Block not found on disk. This could be because we have the block
+        // header in our index but don't have the block (for example if a
+        // non-whitelisted node sends us an unrequested long chain of valid
+        // blocks, we add the headers to our index, but don't accept the
+        // block).
+        throw JSONRPCError(RPC_MISC_ERROR, "Block not found on disk");
 
     if (!fVerbose)
     {
@@ -829,7 +834,7 @@ UniValue pruneblockchain(const JSONRPCRequest& request)
             + HelpExampleRpc("pruneblockchain", "1000"));
 
     if (!fPruneMode)
-        throw JSONRPCError(RPC_METHOD_NOT_FOUND, "Cannot prune blocks because node is not in prune mode.");
+        throw JSONRPCError(RPC_MISC_ERROR, "Cannot prune blocks because node is not in prune mode.");
 
     LOCK(cs_main);
 
@@ -843,7 +848,7 @@ UniValue pruneblockchain(const JSONRPCRequest& request)
         // Add a 2 hour buffer to include blocks which might have had old timestamps
         CBlockIndex* pindex = chainActive.FindEarliestAtLeast(heightParam - TIMESTAMP_WINDOW);
         if (!pindex) {
-            throw JSONRPCError(RPC_INTERNAL_ERROR, "Could not find block with at least the specified timestamp.");
+            throw JSONRPCError(RPC_INVALID_PARAMETER, "Could not find block with at least the specified timestamp.");
         }
         heightParam = pindex->nHeight;
     }
@@ -851,7 +856,7 @@ UniValue pruneblockchain(const JSONRPCRequest& request)
     unsigned int height = (unsigned int) heightParam;
     unsigned int chainHeight = (unsigned int) chainActive.Height();
     if (chainHeight < Params().PruneAfterHeight())
-        throw JSONRPCError(RPC_INTERNAL_ERROR, "Blockchain is too short for pruning.");
+        throw JSONRPCError(RPC_MISC_ERROR, "Blockchain is too short for pruning.");
     else if (height > chainHeight)
         throw JSONRPCError(RPC_INVALID_PARAMETER, "Blockchain is shorter than the attempted prune height.");
     else if (height > chainHeight - MIN_BLOCKS_TO_KEEP) {
diff --git a/src/rpc/net.cpp b/src/rpc/net.cpp
index b946a64ec6..44c6e6d308 100644
--- a/src/rpc/net.cpp
+++ b/src/rpc/net.cpp
@@ -504,7 +504,7 @@ UniValue setban(const JSONRPCRequest& request)
         LookupSubNet(request.params[0].get_str().c_str(), subNet);
 
     if (! (isSubnet ? subNet.IsValid() : netAddr.IsValid()) )
-        throw JSONRPCError(RPC_CLIENT_NODE_ALREADY_ADDED, "Error: Invalid IP/Subnet");
+        throw JSONRPCError(RPC_CLIENT_INVALID_IP_OR_SUBNET, "Error: Invalid IP/Subnet");
 
     if (strCommand == "add")
     {
@@ -524,7 +524,7 @@ UniValue setban(const JSONRPCRequest& request)
     else if(strCommand == "remove")
     {
         if (!( isSubnet ? g_connman->Unban(subNet) : g_connman->Unban(netAddr) ))
-            throw JSONRPCError(RPC_MISC_ERROR, "Error: Unban failed");
+            throw JSONRPCError(RPC_CLIENT_INVALID_IP_OR_SUBNET, "Error: Unban failed. Requested address/subnet was not previously banned.");
     }
     return NullUniValue;
 }
diff --git a/src/rpc/protocol.h b/src/rpc/protocol.h
index 47e56e712b..eafb8d9e67 100644
--- a/src/rpc/protocol.h
+++ b/src/rpc/protocol.h
@@ -31,9 +31,15 @@ enum HTTPStatusCode
 enum RPCErrorCode
 {
     //! Standard JSON-RPC 2.0 errors
+    // RPC_INVALID_REQUEST is internally mapped to HTTP_BAD_REQUEST (400).
+    // It should not be used for application-layer errors.
     RPC_INVALID_REQUEST  = -32600,
+    // RPC_METHOD_NOT_FOUND is internally mapped to HTTP_NOT_FOUND (404).
+    // It should not be used for application-layer errors.
     RPC_METHOD_NOT_FOUND = -32601,
     RPC_INVALID_PARAMS   = -32602,
+    // RPC_INTERNAL_ERROR should only be used for genuine errors in bitcoind
+    // (for exampled datadir corruption).
     RPC_INTERNAL_ERROR   = -32603,
     RPC_PARSE_ERROR      = -32700,