net: recognize I2P from ParseNetwork() so that -onlynet=i2p works, do…

… not skip I2P in GetNetworkNames()

Summary:
> net: recognize I2P from ParseNetwork() so that -onlynet=i2p works
bitcoin/bitcoin@0181e24

> net: Do not skip the I2P network from GetNetworkNames()
>
> So that help texts include "i2p" in:
> * `./bitcoind -help` (in `-onlynet` description)
> * `getpeerinfo` RPC
> * `getnetworkinfo` RPC
>
> Co-authored-by: Jon Atack <jon@atack.com>
bitcoin/bitcoin@a701fcf

This concludes backport of [[bitcoin/bitcoin#20685 | core#20685]] [19,20/20]
Depends on D11029 and D11036

Test Plan:
`ninja all check-all`

`src/bitcoind -regtest -i2psam=127.0.0.1:7656 -onlynet=i2p -debug=i2p`

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Subscribers: Fabien

Differential Revision: https://reviews.bitcoinabc.org/D11037

src/init.cpp

@@ -753,7 +753,7 @@ void SetupServerArgs(NodeContext &node) {
             Join(GetNetworkNames(), ", ") +
             "). Incoming connections are not affected by this option. This "
             "option can be specified multiple times to allow multiple "
-            "networks. Warning: if it is used with ipv4 or ipv6 but not onion "
+            "networks. Warning: if it is used with non-onion networks "
             "and the -onion or -proxy option is set, then outbound onion "
             "connections will still be made; use -noonion or -onion=0 to "
             "disable outbound onion connections in this case",

src/netbase.cpp

@@ -58,6 +58,9 @@ enum Network ParseNetwork(const std::string &net_in) {
                   "in the future. You should use 'onion' instead.\n");
         return NET_ONION;
     }
+    if (net == "i2p") {
+        return NET_I2P;
+    }
     return NET_UNROUTABLE;
 }
 
@@ -88,8 +91,8 @@ std::vector<std::string> GetNetworkNames(bool append_unroutable) {
     std::vector<std::string> names;
     for (int n = 0; n < NET_MAX; ++n) {
         const enum Network network { static_cast<Network>(n) };
-        if (network == NET_UNROUTABLE || network == NET_I2P ||
-            network == NET_CJDNS || network == NET_INTERNAL) {
+        if (network == NET_UNROUTABLE || network == NET_CJDNS ||
+            network == NET_INTERNAL) {
             continue;
         }
         names.emplace_back(GetNetworkName(network));

test/functional/rpc_net.py

@@ -142,7 +142,9 @@ def test_getnetworkinfo(self):
 
         # Check dynamically generated networks list in getnetworkinfo help
         # output.
-        assert "(ipv4, ipv6, onion)" in self.nodes[0].help("getnetworkinfo")
+        assert (
+            "(ipv4, ipv6, onion, i2p)" in self.nodes[0].help("getnetworkinfo")
+        )
 
     def test_getaddednodeinfo(self):
         self.log.info("Test getaddednodeinfo")
@@ -219,7 +221,7 @@ def test_getpeerinfo(self):
 
         # Check dynamically generated networks list in getpeerinfo help output.
         assert (
-            "(ipv4, ipv6, onion, not_publicly_routable)" in
+            "(ipv4, ipv6, onion, i2p, not_publicly_routable)" in
             self.nodes[0].help("getpeerinfo")
         )