merge bitcoin#22648: improve i2p/tor docs and i2p reachable unit tests

Author: kwvg

doc/i2p.md

@@ -10,11 +10,22 @@ started with I2P terminology.
 ## Run Dash Core with an I2P router (proxy)
 
 A running I2P router (proxy) with [SAM](https://geti2p.net/en/docs/api/samv3)
-enabled is required (there is an [official one](https://geti2p.net) and
-[a few alternatives](https://en.wikipedia.org/wiki/I2P#Routers)). Notice the IP
-address and port the SAM proxy is listening to; usually, it is
-`127.0.0.1:7656`. Once it is up and running with SAM enabled, use the following
-Dash Core options:
+enabled is required. Options include:
+
+- [i2prouter (I2P Router)](https://geti2p.net), the official implementation in
+  Java
+- [i2pd (I2P Daemon)](https://github.com/PurpleI2P/i2pd)
+  ([documentation](https://i2pd.readthedocs.io/en/latest)), a lighter
+  alternative in C++ (successfully tested with version 2.23 and up; version 2.36
+  or later recommended)
+- [i2p-zero](https://github.com/i2p-zero/i2p-zero)
+- [other alternatives](https://en.wikipedia.org/wiki/I2P#Routers)
+
+Note the IP address and port the SAM proxy is listening to; usually, it is
+`127.0.0.1:7656`.
+
+Once an I2P router with SAM enabled is up and running, use the following Dash
+Core configuration options:
 
 ```
 -i2psam=<ip:port>
@@ -42,15 +53,30 @@ named `i2p_private_key` in the Dash Core data directory.
 
 ## Additional configuration options related to I2P
 
-You may set the `debug=i2p` config logging option to have additional
-information in the debug log about your I2P configuration and connections. Run
-`dash-cli help logging` for more information.
+```
+-debug=i2p
+```
+
+Set the `debug=i2p` config logging option to see additional information in the
+debug log about your I2P configuration and connections. Run `dash-cli help
+logging` for more information.
+
+```
+-onlynet=i2p
+```
+
+Make outgoing connections only to I2P addresses. Incoming connections are not
+affected by this option. It can be specified multiple times to allow multiple
+network types, e.g. onlynet=ipv4, onlynet=ipv6, onlynet=onion, onlynet=i2p.
+
+Warning: if you use -onlynet with values other than onion, and the -onion or
+-proxy option is set, then outgoing onion connections will still be made; use
+-noonion or -onion=0 to disable outbound onion connections in this case.
 
-It is possible to restrict outgoing connections in the usual way with
-`onlynet=i2p`. I2P support was added to Dash Core in version 20.0 (fall-2023)
-and there may be fewer I2P peers than Tor or IP ones. Therefore, using
-`onlynet=i2p` alone (without other `onlynet=`) may make a node more susceptible
-to [Sybil attacks](https://en.dash.it/wiki/Weaknesses#Sybil_attack). Use
+I2P support was added to Dash Core in version 20.0 and there may be fewer I2P
+peers than Tor or IP ones. Therefore, using I2P alone without other networks may
+make a node more susceptible to [Sybil
+attacks](https://en.bitcoin.it/wiki/Weaknesses#Sybil_attack). You can use
 `dash-cli -addrinfo` to see the number of I2P addresses known to your node.
 
 Another consideration with `onlynet=i2p` is that the initial blocks download

doc/tor.md

@@ -51,11 +51,11 @@ outgoing connections, but more is possible.
     -onlynet=onion  Make outgoing connections only to .onion addresses. Incoming
                     connections are not affected by this option. This option can be
                     specified multiple times to allow multiple network types, e.g.
-                    ipv4, ipv6 or onion. If you use this option with values other
-                    than onion you *cannot* disable onion connections; outgoing onion
-                    connections will be enabled when you use -proxy or -onion. Use
-                    -noonion or -onion=0 if you want to be sure there are no outbound
-                    onion connections over the default proxy or your defined -proxy.
+                    onlynet=ipv4, onlynet=ipv6, onlynet=onion, onlynet=i2p.
+                    Warning: if you use -onlynet with values other than onion, and
+                    the -onion or -proxy option is set, then outgoing onion
+                    connections will still be made; use -noonion or -onion=0 to
+                    disable outbound onion connections in this case.
 
 An example how to start the client if the Tor proxy is running on local host on
 port 9050 and only allows .onion nodes to connect:

src/test/net_tests.cpp

@@ -761,37 +761,42 @@ BOOST_AUTO_TEST_CASE(ipv4_peer_with_ipv6_addrMe_test)
 
 BOOST_AUTO_TEST_CASE(LimitedAndReachable_Network)
 {
-    BOOST_CHECK_EQUAL(IsReachable(NET_IPV4), true);
-    BOOST_CHECK_EQUAL(IsReachable(NET_IPV6), true);
-    BOOST_CHECK_EQUAL(IsReachable(NET_ONION), true);
+    BOOST_CHECK(IsReachable(NET_IPV4));
+    BOOST_CHECK(IsReachable(NET_IPV6));
+    BOOST_CHECK(IsReachable(NET_ONION));
+    BOOST_CHECK(IsReachable(NET_I2P));
 
     SetReachable(NET_IPV4, false);
     SetReachable(NET_IPV6, false);
     SetReachable(NET_ONION, false);
+    SetReachable(NET_I2P, false);
 
-    BOOST_CHECK_EQUAL(IsReachable(NET_IPV4), false);
-    BOOST_CHECK_EQUAL(IsReachable(NET_IPV6), false);
-    BOOST_CHECK_EQUAL(IsReachable(NET_ONION), false);
+    BOOST_CHECK(!IsReachable(NET_IPV4));
+    BOOST_CHECK(!IsReachable(NET_IPV6));
+    BOOST_CHECK(!IsReachable(NET_ONION));
+    BOOST_CHECK(!IsReachable(NET_I2P));
 
     SetReachable(NET_IPV4, true);
     SetReachable(NET_IPV6, true);
     SetReachable(NET_ONION, true);
+    SetReachable(NET_I2P, true);
 
-    BOOST_CHECK_EQUAL(IsReachable(NET_IPV4), true);
-    BOOST_CHECK_EQUAL(IsReachable(NET_IPV6), true);
-    BOOST_CHECK_EQUAL(IsReachable(NET_ONION), true);
+    BOOST_CHECK(IsReachable(NET_IPV4));
+    BOOST_CHECK(IsReachable(NET_IPV6));
+    BOOST_CHECK(IsReachable(NET_ONION));
+    BOOST_CHECK(IsReachable(NET_I2P));
 }
 
 BOOST_AUTO_TEST_CASE(LimitedAndReachable_NetworkCaseUnroutableAndInternal)
 {
-    BOOST_CHECK_EQUAL(IsReachable(NET_UNROUTABLE), true);
-    BOOST_CHECK_EQUAL(IsReachable(NET_INTERNAL), true);
+    BOOST_CHECK(IsReachable(NET_UNROUTABLE));
+    BOOST_CHECK(IsReachable(NET_INTERNAL));
 
     SetReachable(NET_UNROUTABLE, false);
     SetReachable(NET_INTERNAL, false);
 
-    BOOST_CHECK_EQUAL(IsReachable(NET_UNROUTABLE), true); // Ignored for both networks
-    BOOST_CHECK_EQUAL(IsReachable(NET_INTERNAL), true);
+    BOOST_CHECK(IsReachable(NET_UNROUTABLE)); // Ignored for both networks
+    BOOST_CHECK(IsReachable(NET_INTERNAL));
 }
 
 CNetAddr UtilBuildAddress(unsigned char p1, unsigned char p2, unsigned char p3, unsigned char p4)
@@ -810,10 +815,10 @@ BOOST_AUTO_TEST_CASE(LimitedAndReachable_CNetAddr)
     CNetAddr addr = UtilBuildAddress(0x001, 0x001, 0x001, 0x001); // 1.1.1.1
 
     SetReachable(NET_IPV4, true);
-    BOOST_CHECK_EQUAL(IsReachable(addr), true);
+    BOOST_CHECK(IsReachable(addr));
 
     SetReachable(NET_IPV4, false);
-    BOOST_CHECK_EQUAL(IsReachable(addr), false);
+    BOOST_CHECK(!IsReachable(addr));
 
     SetReachable(NET_IPV4, true); // have to reset this, because this is stateful.
 }
@@ -825,12 +830,12 @@ BOOST_AUTO_TEST_CASE(LocalAddress_BasicLifecycle)
 
     SetReachable(NET_IPV4, true);
 
-    BOOST_CHECK_EQUAL(IsLocal(addr), false);
-    BOOST_CHECK_EQUAL(AddLocal(addr, 1000), true);
-    BOOST_CHECK_EQUAL(IsLocal(addr), true);
+    BOOST_CHECK(!IsLocal(addr));
+    BOOST_CHECK(AddLocal(addr, 1000));
+    BOOST_CHECK(IsLocal(addr));
 
     RemoveLocal(addr);
-    BOOST_CHECK_EQUAL(IsLocal(addr), false);
+    BOOST_CHECK(!IsLocal(addr));
 }
 
 BOOST_AUTO_TEST_SUITE_END()