init: Abort if i2p/cjdns are chosen via -onlynet but unreachable

...because -i2psam or -cjdnsreachable are not provided.
This mimics existing behavior for -onlynet=onion and non-specified proxy.

Author: mzumsande

src/init.cpp

@@ -1284,6 +1284,11 @@ bool AppInitMain(NodeContext& node, interfaces::BlockAndHeaderTipInfo* tip_info)
     }
 
     if (!args.IsArgSet("-cjdnsreachable")) {
+        if (args.IsArgSet("-onlynet") && IsReachable(NET_CJDNS)) {
+            return InitError(
+                _("Outbound connections restricted to CJDNS (-onlynet=cjdns) but "
+                  "-cjdnsreachable is not provided"));
+        }
         SetReachable(NET_CJDNS, false);
     }
     // Now IsReachable(NET_CJDNS) is true if:
@@ -1756,6 +1761,11 @@ bool AppInitMain(NodeContext& node, interfaces::BlockAndHeaderTipInfo* tip_info)
         }
         SetProxy(NET_I2P, Proxy{addr});
     } else {
+        if (args.IsArgSet("-onlynet") && IsReachable(NET_I2P)) {
+            return InitError(
+                _("Outbound connections restricted to i2p (-onlynet=i2p) but "
+                  "-i2psam is not provided"));
+        }
         SetReachable(NET_I2P, false);
     }
 

test/functional/feature_proxy.py

@@ -332,6 +332,16 @@ def networks_dict(d):
         msg = "Error: Invalid -i2psam address or hostname: 'def:xyz'"
         self.nodes[1].assert_start_raises_init_error(expected_msg=msg)
 
+        self.log.info("Test passing invalid -onlynet=i2p without -i2psam raises expected init error")
+        self.nodes[1].extra_args = ["-onlynet=i2p"]
+        msg = "Error: Outbound connections restricted to i2p (-onlynet=i2p) but -i2psam is not provided"
+        self.nodes[1].assert_start_raises_init_error(expected_msg=msg)
+
+        self.log.info("Test passing invalid -onlynet=cjdns without -cjdnsreachable raises expected init error")
+        self.nodes[1].extra_args = ["-onlynet=cjdns"]
+        msg = "Error: Outbound connections restricted to CJDNS (-onlynet=cjdns) but -cjdnsreachable is not provided"
+        self.nodes[1].assert_start_raises_init_error(expected_msg=msg)
+
         self.log.info("Test passing -onlynet=onion with -onion=0/-noonion raises expected init error")
         msg = (
             "Error: Outbound connections restricted to Tor (-onlynet=onion) but "