p2p: name $DOG Mode in the user agent

doc/release-notes-dogmode-user-agent.md

@@ -0,0 +1,12 @@
+$DOG Mode user agent
+====================
+
+P2P
+---
+
+- The user agent names $DOG Mode after Bitcoin Core's own component, for
+  example `/Satoshi:31.1.0/DOGMode:20260902/`, the way Bitcoin Knots names
+  itself. A peer, a DNS seed's crawler, `getpeerinfo` and `getnetworkinfo` can
+  now tell a $DOG Mode node, and which release it runs, from plain Bitcoin
+  Core. The Bitcoin Core component is unchanged, and `-uacomment` comments
+  still attach to it.

src/clientversion.cpp

@@ -23,6 +23,15 @@ using util::Join;
  */
 const std::string UA_NAME("Satoshi");
 
+/**
+ * $DOG Mode's name and version, reported in the 'version' message as a second
+ * BIP 14 component after the Bitcoin Core one above, the way Bitcoin Knots
+ * reports itself: "/Satoshi:31.1.0/DOGMode:20260902/". The Bitcoin Core
+ * component stays first and unchanged. The version is a date (YYYYMMDD), as
+ * BIP 14 recommends; set it to the release date when a release is tagged.
+ */
+const std::string UA_DOGMODE("DOGMode:20260902");
+
 
 #include <bitcoin-build-info.h>
 // The <bitcoin-build-info.h>, which is generated by the build environment (cmake/script/GenerateBuildInfo.cmake),

src/clientversion.h

@@ -29,6 +29,7 @@ static const int CLIENT_VERSION =
                          +       1 * CLIENT_VERSION_BUILD;
 
 extern const std::string UA_NAME;
+extern const std::string UA_DOGMODE;
 
 
 std::string FormatFullVersion();

src/init.cpp

@@ -1679,7 +1679,7 @@ bool AppInitMain(NodeContext& node, interfaces::BlockAndHeaderTipInfo* tip_info)
             return InitError(strprintf(_("User Agent comment (%s) contains unsafe characters."), cmt));
         uacomments.push_back(cmt);
     }
-    strSubVersion = FormatSubVersion(UA_NAME, CLIENT_VERSION, uacomments);
+    strSubVersion = FormatSubVersion(UA_NAME, CLIENT_VERSION, uacomments) + UA_DOGMODE + "/";
     if (strSubVersion.size() > MAX_SUBVERSION_LENGTH) {
         return InitError(strprintf(_("Total length of network version string (%i) exceeds maximum length (%i). Reduce the number or size of uacomments."),
             strSubVersion.size(), MAX_SUBVERSION_LENGTH));

test/functional/feature_includeconf.py

@@ -33,10 +33,10 @@ def run_test(self):
             f.write("uacomment=main\nincludeconf=relative.conf\n")
         self.restart_node(0)
 
-        self.log.info("-includeconf works from config file. subversion should end with 'main; relative)/'")
+        self.log.info("-includeconf works from config file. subversion should contain 'main; relative)/'")
 
         subversion = self.nodes[0].getnetworkinfo()["subversion"]
-        assert subversion.endswith("main; relative)/")
+        assert "main; relative)/" in subversion
 
         self.log.info("-includeconf cannot be used as command-line arg")
         self.stop_node(0)
@@ -49,13 +49,13 @@ def run_test(self):
             expected_msg='Error: Error parsing command line arguments: -includeconf cannot be used from commandline; -includeconf="relative2.conf"',
         )
 
-        self.log.info("-includeconf cannot be used recursively. subversion should end with 'main; relative)/'")
+        self.log.info("-includeconf cannot be used recursively. subversion should contain 'main; relative)/'")
         with open(self.nodes[0].datadir_path / "relative.conf", "a") as f:
             f.write("includeconf=relative2.conf\n")
         self.start_node(0)
 
         subversion = self.nodes[0].getnetworkinfo()["subversion"]
-        assert subversion.endswith("main; relative)/")
+        assert "main; relative)/" in subversion
         self.stop_node(0, expected_stderr="warning: -includeconf cannot be used from included files; ignoring -includeconf=relative2.conf")
 
         self.log.info("-includeconf cannot contain invalid arg")
@@ -69,7 +69,7 @@ def run_test(self):
         (self.nodes[0].datadir_path / "relative.conf").unlink()
         self.nodes[0].assert_start_raises_init_error(expected_msg="Error: Error reading configuration file: Failed to include configuration file relative.conf")
 
-        self.log.info("multiple -includeconf args can be used from the base config file. subversion should end with 'main; relative; relative2)/'")
+        self.log.info("multiple -includeconf args can be used from the base config file. subversion should contain 'main; relative; relative2)/'")
         with open(self.nodes[0].datadir_path / "relative.conf", "w") as f:
             # Restore initial file contents
             f.write("uacomment=relative\n")
@@ -80,7 +80,7 @@ def run_test(self):
         self.start_node(0)
 
         subversion = self.nodes[0].getnetworkinfo()["subversion"]
-        assert subversion.endswith("main; relative; relative2)/")
+        assert "main; relative; relative2)/" in subversion
 
 if __name__ == '__main__':
     IncludeConfTest(__file__).main()

test/functional/feature_uacomment.py

@@ -2,10 +2,11 @@
 # Copyright (c) 2017-present The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
-"""Test the -uacomment option."""
+"""Test the -uacomment option, and the $DOG Mode component of the user agent."""
 
 import re
 
+from test_framework.p2p import P2PInterface
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.test_node import ErrorMatch
 from test_framework.util import assert_equal
@@ -17,13 +18,17 @@ def set_test_params(self):
         self.setup_clean_chain = True
 
     def run_test(self):
-        self.log.info("test multiple -uacomment")
-        test_uacomment = self.nodes[0].getnetworkinfo()["subversion"][-12:-1]
-        assert_equal(test_uacomment, "(testnode0)")
+        self.log.info("test multiple -uacomment, on the Bitcoin Core component, followed by the $DOG Mode one")
+        test_uacomment = self.nodes[0].getnetworkinfo()["subversion"]
+        assert re.fullmatch(r"/Satoshi:\d+\.\d+\.\d+\(testnode0\)/DOGMode:[^/:()]+/", test_uacomment), test_uacomment
 
         self.restart_node(0, ["-uacomment=foo"])
-        foo_uacomment = self.nodes[0].getnetworkinfo()["subversion"][-17:-1]
-        assert_equal(foo_uacomment, "(testnode0; foo)")
+        foo_uacomment = self.nodes[0].getnetworkinfo()["subversion"]
+        assert re.fullmatch(r"/Satoshi:\d+\.\d+\.\d+\(testnode0; foo\)/DOGMode:[^/:()]+/", foo_uacomment), foo_uacomment
+
+        self.log.info("test peers receive the same user agent")
+        peer = self.nodes[0].add_p2p_connection(P2PInterface())
+        assert_equal(peer.last_message["version"].strSubVer, foo_uacomment)
 
         self.log.info("test -uacomment max length")
         self.stop_node(0)