doc: Expand documentation on asmap feature and tooling

contrib/README.md

@@ -18,6 +18,9 @@ A Linux bash script that will set up traffic control (tc) to limit the outgoing
 ### [Seeds](/contrib/seeds) ###
 Utility to generate the pnSeed[] array that is compiled into the client.
 
+### [ASMap](/contrib/asmap) ###
+Utilities to analyze and process asmap files.
+
 Build Tools and Keys
 ---------------------
 

contrib/asmap/README.md

@@ -4,9 +4,35 @@ Tool for performing various operations on textual and binary asmap files,
 particularly encoding/compressing the raw data to the binary format that can
 be used in Bitcoin Core with the `-asmap` option.
 
-Example usage:
+## Example usage
+
+To decode/encode asmap files use the `decode` and `encode` commands.
+
 ```
 python3 asmap-tool.py encode /path/to/input.file /path/to/output.file
 python3 asmap-tool.py decode /path/to/input.file /path/to/output.file
+```
+
+The `diff` command computes the differences between two asmap files. They can
+be text or binary.
+
+```
 python3 asmap-tool.py diff /path/to/first.file /path/to/second.file
 ```
+
+The `diff_addrs` command computes the differences between two asmap files but
+limited to a set of addresses that need to be passed as a third argument. This
+should be a list of known addresses from `getnodeaddresses`.
+
+```
+bitcoin-cli getnodeaddresses 0 > addrs.json
+python3 asmap-tool.py diff /path/to/first.file /path/to/second.file addrs.json
+```
+
+The `gen_header` command generates a header file from a given asmap file and
+is used in the build process to generate the header file containing the
+asmap data embedded in the binary.
+
+```
+python3 asmap-tool.py gen_header /path/to/asmap.dat /path/to/asmap.h
+```

src/init.cpp

@@ -527,7 +527,14 @@ void SetupServerArgs(ArgsManager& argsman)
                  ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
 
     argsman.AddArg("-addnode=<ip>", strprintf("Add a node to connect to and attempt to keep the connection open (see the addnode RPC help for more info). This option can be specified multiple times to add multiple nodes; connections are limited to %u at a time and are counted separately from the -maxconnections limit.", MAX_ADDNODE_CONNECTIONS), ArgsManager::ALLOW_ANY | ArgsManager::NETWORK_ONLY, OptionsCategory::CONNECTION);
-    argsman.AddArg("-asmap=<file>", strprintf("Specify asn mapping used for bucketing of the peers (default: %s). Relative paths will be prefixed by the net-specific datadir location.", DEFAULT_ASMAP_FILENAME), ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
+    argsman.AddArg("-asmap=<file>", strprintf("Use IP to ASN mapping for bucketing of the peers. If a file argument is not given (-asmap or -asmap=1), a file in the default location (%s) will be used.%s Relative paths will be prefixed by the net-specific datadir location.",
+                DEFAULT_ASMAP_FILENAME,
+                #ifdef ENABLE_EMBEDDED_ASMAP
+                    " If no file is found there, the embedded mapping data in the binary will be used as a fallback."
+                #else
+                    ""
+                #endif
+                ), ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     argsman.AddArg("-bantime=<n>", strprintf("Default duration (in seconds) of manually configured bans (default: %u)", DEFAULT_MISBEHAVING_BANTIME), ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     argsman.AddArg("-bind=<addr>[:<port>][=onion]", strprintf("Bind to given address and always listen on it (default: 0.0.0.0). Use [host]:port notation for IPv6. Append =onion to tag any incoming connections to that address and port as incoming Tor connections (default: 127.0.0.1:%u=onion, testnet3: 127.0.0.1:%u=onion, testnet4: 127.0.0.1:%u=onion, signet: 127.0.0.1:%u=onion, regtest: 127.0.0.1:%u=onion)", defaultBaseParams->OnionServiceTargetPort(), testnetBaseParams->OnionServiceTargetPort(), testnet4BaseParams->OnionServiceTargetPort(), signetBaseParams->OnionServiceTargetPort(), regtestBaseParams->OnionServiceTargetPort()), ArgsManager::ALLOW_ANY | ArgsManager::NETWORK_ONLY, OptionsCategory::CONNECTION);
     argsman.AddArg("-cjdnsreachable", "If set, then this host is configured for CJDNS (connecting to fc00::/8 addresses would lead us to the CJDNS network, see doc/cjdns.md) (default: 0)", ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);