test(rpc): Add a script for comparing zcashd and zebrad RPC responses (#4219)

* Add a tool for comparing zcashd and zebrad RPC responses

* Add the network to the RPC diff logs

This helps diagnose main/test mismatches.

* Warn when heights or networks are different

* Move diff script to utils

* Document zcash-rpc-diff script

* Rename a confusing internal script env var

zebra-utils/README.md

@@ -7,6 +7,7 @@ This crate contains tools for zebra maintainers.
 - [zebra-checkpoints](#zebra-checkpoints)
 - [zebrad-hash-lookup](#zebrad-hash-lookup)
 - [zebrad-log-filter](#zebrad-log-filter)
+- [zcash-rpc-diff](#zcash-rpc-diff)
 
 Binaries are easier to use if they are located in your system execution path.
 
@@ -70,3 +71,63 @@ next: 00000001436277884eef900772f0fcec9566becccebaab4713fd665b60fab309
 "))) max_checkpoint_height=Height(419581)
 ...
 ```
+
+### zcash-rpc-diff
+
+This program compares `zebrad` and `zcashd` RPC responses.
+
+Make sure you have zcashd and zebrad installed and synced.
+
+The script:
+1. gets the `zebrad` and `zcashd` tip height and network
+2. sends the RPC request to both of them using `zcash-cli`
+3. compares the responses using `diff`
+4. leaves the full responses in files in a temporary directory, so you can check them in detail
+
+Assuming `zebrad`'s RPC port is 28232, you should be able to run:
+```sh
+$ zebra-utils/zcash-rpc-diff 28232 getinfo
+Checking zebrad network and tip height...
+Checking zcashd network and tip height...
+
+Request:
+getinfo
+
+Querying zebrad main chain at height 1649797...
+Querying zcashd main chain at height 1649797...
+
+Response diff (between zcashd port and port 28232):
+--- /run/user/1000/tmp.g9CJecu2Wo/zebrad-main-1649797-getinfo.json      2022-04-29 14:08:46.766240355 +1000
++++ /run/user/1000/tmp.g9CJecu2Wo/zcashd-main-1649797-getinfo.json      2022-04-29 14:08:46.769240315 +1000
+@@ -1,4 +1,16 @@
+ {
+-  "build": "1.0.0-beta.8+54.ge83e93a",
+-  "subversion": "/Zebra:1.0.0-beta.8/"
++  "version": 4070050,
++  "build": "v4.7.0-gitian",
++  "subversion": "/MagicBean:4.7.0/",
+... more extra zcashd fields ...
+ }
+```
+
+Sometimes zcashd will have extra fields (`+`) or different data (`-` and `+`).
+And sometimes it will have the same data, but in a different order.
+
+The script will warn you if the heights or networks are different,
+then display the results of querying the mismatched node states.
+
+The script accepts any RPC, with any number of arguments.
+If a node doesn't implement an RPC, the script will exit with an error.
+
+#### Configuration
+
+The script uses the configured `zcash-cli` RPC port,
+and the `zebrad` port supplied on the command-line.
+
+It doesn't actually check what kind of node it is talking to,
+so you can compare two `zcashd` or `zebrad` nodes if you want.
+(Just edit the `zcash.conf` file used by `zcash-cli`, or edit the script.)
+
+You can override the binaries the script calls using these environmental variables:
+- `$ZCASH_CLI`
+- `$DIFF`

zebra-utils/zcash-rpc-diff

@@ -0,0 +1,84 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+# Sends a `zcash-cli` command to a Zebra and zcashd instance,
+# and compares the results.
+#
+# Uses the configured `zcash-cli` RPC port,
+# and the `zebrad` port supplied on the command-line.
+
+function usage()
+{
+    echo "Usage:"
+    echo "$0 zebra-rpc-port rpc-name [rpc-args... ]"
+}
+
+# Override the commands used by this script using these environmental variables:
+ZCASH_CLI="${ZCASH_CLI:-zcash-cli}"
+DIFF="${DIFF:-diff --unified --color}"
+
+if [ $# -lt 2 ]; then
+    usage
+    exit 1
+fi
+
+ZEBRAD_RPC_PORT=$1
+shift
+
+ZCASH_RPC_TMP_DIR=$(mktemp -d)
+
+ZEBRAD_BLOCKCHAIN_INFO="$ZCASH_RPC_TMP_DIR/zebrad-check-getblockchaininfo.json"
+ZCASHD_BLOCKCHAIN_INFO="$ZCASH_RPC_TMP_DIR/zcashd-check-getblockchaininfo.json"
+
+echo "Checking zebrad network and tip height..."
+$ZCASH_CLI -rpcport="$ZEBRAD_RPC_PORT" getblockchaininfo > "$ZEBRAD_BLOCKCHAIN_INFO"
+
+ZEBRAD_NET=$(cat "$ZEBRAD_BLOCKCHAIN_INFO" | grep '"chain"' | cut -d: -f2 | tr -d ' ,"')
+ZEBRAD_HEIGHT=$(cat "$ZEBRAD_BLOCKCHAIN_INFO" | grep '"blocks"' | cut -d: -f2 | tr -d ' ,"')
+
+echo "Checking zcashd network and tip height..."
+$ZCASH_CLI getblockchaininfo > "$ZCASHD_BLOCKCHAIN_INFO"
+
+ZCASHD_NET=$(cat "$ZCASHD_BLOCKCHAIN_INFO" | grep '"chain"' | cut -d: -f2 | tr -d ' ,"')
+ZCASHD_HEIGHT=$(cat "$ZCASHD_BLOCKCHAIN_INFO" | grep '"blocks"' | cut -d: -f2 | tr -d ' ,"')
+
+echo
+
+if [ "$ZEBRAD_NET" != "$ZCASHD_NET" ]; then
+    echo "WARNING: comparing RPC responses from different networks:"
+    echo "zcashd is on: $ZCASHD_NET"
+    echo "zebrad is on: $ZEBRAD_NET"
+    echo
+fi
+
+if [ "$ZEBRAD_HEIGHT" -ne "$ZCASHD_HEIGHT" ]; then
+    echo "WARNING: comparing RPC responses from different heights:"
+    echo "zcashd is at: $ZCASHD_HEIGHT"
+    echo "zebrad is at: $ZEBRAD_HEIGHT"
+    echo
+fi
+
+ZEBRAD_RESPONSE="$ZCASH_RPC_TMP_DIR/zebrad-$ZEBRAD_NET-$ZEBRAD_HEIGHT-$1.json"
+ZCASHD_RESPONSE="$ZCASH_RPC_TMP_DIR/zcashd-$ZCASHD_NET-$ZCASHD_HEIGHT-$1.json"
+
+echo "Request:"
+echo "$@"
+echo
+
+echo "Querying zebrad $ZEBRAD_NET chain at height $ZEBRAD_HEIGHT..."
+$ZCASH_CLI -rpcport="$ZEBRAD_RPC_PORT" "$@" > "$ZEBRAD_RESPONSE"
+
+echo "Querying zcashd $ZCASHD_NET chain at height $ZCASHD_HEIGHT..."
+$ZCASH_CLI "$@" > "$ZCASHD_RESPONSE"
+
+echo
+
+echo "Response diff (between zcashd port and port $ZEBRAD_RPC_PORT):"
+$DIFF "$ZEBRAD_RESPONSE" "$ZCASHD_RESPONSE" \
+    && ( \
+        echo "RPC responses were identical"; \
+        echo ; \
+        echo "$ZEBRAD_RESPONSE:"; \
+        cat "$ZEBRAD_RESPONSE"; \
+        )