test: implement ser/unser of I2P addresses in functional tests

Author: vasild

test/functional/test_framework/messages.py

@@ -18,6 +18,7 @@
 Classes use __slots__ to ensure extraneous attributes aren't accidentally added
 by tests, compromising their intended effect.
 """
+from base64 import b32decode, b32encode
 from codecs import encode
 import copy
 import hashlib
@@ -207,15 +208,20 @@ class CAddress:
 
     # see https://github.com/bitcoin/bips/blob/master/bip-0155.mediawiki
     NET_IPV4 = 1
+    NET_I2P = 5
 
     ADDRV2_NET_NAME = {
-        NET_IPV4: "IPv4"
+        NET_IPV4: "IPv4",
+        NET_I2P: "I2P"
     }
 
     ADDRV2_ADDRESS_LENGTH = {
-        NET_IPV4: 4
+        NET_IPV4: 4,
+        NET_I2P: 32
     }
 
+    I2P_PAD = "===="
+
     def __init__(self):
         self.time = 0
         self.nServices = 1
@@ -255,24 +261,33 @@ def deserialize_v2(self, f):
         self.nServices = deser_compact_size(f)
 
         self.net = struct.unpack("B", f.read(1))[0]
-        assert self.net == self.NET_IPV4
+        assert self.net in (self.NET_IPV4, self.NET_I2P)
 
         address_length = deser_compact_size(f)
         assert address_length == self.ADDRV2_ADDRESS_LENGTH[self.net]
 
-        self.ip = socket.inet_ntoa(f.read(4))
+        addr_bytes = f.read(address_length)
+        if self.net == self.NET_IPV4:
+            self.ip = socket.inet_ntoa(addr_bytes)
+        else:
+            self.ip = b32encode(addr_bytes)[0:-len(self.I2P_PAD)].decode("ascii").lower() + ".b32.i2p"
 
         self.port = struct.unpack(">H", f.read(2))[0]
 
     def serialize_v2(self):
         """Serialize in addrv2 format (BIP155)"""
-        assert self.net == self.NET_IPV4
+        assert self.net in (self.NET_IPV4, self.NET_I2P)
         r = b""
         r += struct.pack("<I", self.time)
         r += ser_compact_size(self.nServices)
         r += struct.pack("B", self.net)
         r += ser_compact_size(self.ADDRV2_ADDRESS_LENGTH[self.net])
-        r += socket.inet_aton(self.ip)
+        if self.net == self.NET_IPV4:
+            r += socket.inet_aton(self.ip)
+        else:
+            sfx = ".b32.i2p"
+            assert self.ip.endswith(sfx)
+            r += b32decode(self.ip[0:-len(sfx)] + self.I2P_PAD, True)
         r += struct.pack(">H", self.port)
         return r