Merge bitcoin/bitcoin#33920: Export embedded ASMap RPC

2a90b6132a Add release notes for exportasmap (Fabian Jahr)
8cb2d926b4 rpc: Add exportasmap RPC (Fabian Jahr)

Pull request description:

  This depends on the embedded data PR itself (#28792), until merge this will remain in draft status. All commit but the last one are from there.

  There has been interest in exporting the embedded data back into a file. This is implemented here with a simple `exportasmap` RPC which provides this functionality. The exported file can be used to verify the data integrity or statistical analysis using e.g. `contrib/asmap-tool.py`.

ACKs for top commit:
  achow101:
    ACK 2a90b6132a
  sedited:
    ACK 2a90b6132a
  seduless:
    Tested ACK 2a90b6132a

Tree-SHA512: c8453078efe916ed95bff0695aabd9123d805970e037fad5e9317f4d43e2a4b21970030265bc82b00f3a222ee3db11346eef1fb6fc9393429b9bc6449f1830f1

test/functional/feature_asmap.py

@@ -11,11 +11,15 @@ with missing and unparseable files.
 The tests are order-independent.
 
 """
+import hashlib
 import os
 import shutil
 
 from test_framework.test_framework import BitcoinTestFramework
-from test_framework.util import assert_equal
+from test_framework.util import (
+    assert_equal,
+    assert_raises_rpc_error,
+)
 
 ASMAP = 'src/test/data/asmap.raw' # path to unit test skeleton asmap
 VERSION = 'bafc9da308f45179443bd1d22325400ac9104f741522d003e3fac86700f68895'
@@ -124,6 +128,29 @@ class AsmapTest(BitcoinTestFramework):
                     asns.append(asn)
         assert_equal(len(asns), 3)
 
+    def test_export_embedded_asmap(self):
+        self.log.info('Test exportasmap RPC')
+        export_path = os.path.join(self.datadir, "asmap.dat")
+
+        if not self.is_embedded_asmap_compiled():
+            assert_raises_rpc_error(-1, "No embedded ASMap data available", self.node.exportasmap, export_path)
+            return
+
+        # Relative paths are resolved against the datadir.
+        result = self.node.exportasmap("asmap.dat")
+        assert_equal(result["path"], export_path)
+
+        with open(export_path, 'rb') as f:
+            data = f.read()
+        assert_equal(result["bytes_written"], len(data))
+
+        # Added in https://github.com/bitcoin/bitcoin/pull/34696
+        expected_hash = "478d61986c59365cf86cd244485bbbe76a9ca0c630864717286dd19949879074"
+        assert_equal(hashlib.sha256(data).hexdigest(), expected_hash)
+        assert_equal(result["file_hash"], expected_hash)
+
+        os.remove(export_path)
+
     def run_test(self):
         self.node = self.nodes[0]
         self.datadir = self.node.chain_path
@@ -139,6 +166,7 @@ class AsmapTest(BitcoinTestFramework):
         self.test_asmap_with_missing_file()
         self.test_empty_asmap()
         self.test_asmap_health_check()
+        self.test_export_embedded_asmap()
 
 
 if __name__ == '__main__':