prop224: Service address creation/validation

This also adds unit test and a small python script generating a deterministic
test vector that a unit test tries to match.

Signed-off-by: David Goulet <dgoulet@torproject.org>

2 files changed, 120 insertions, 0 deletions

diff --git a/src/test/hs_build_address.py b/src/test/hs_build_address.py
new file mode 100644
index 0000000000..7be9c8b85a
--- /dev/null
+++ b/src/test/hs_build_address.py
@@ -0,0 +1,37 @@
+import sys
+import hashlib
+import struct
+import base64
+
+# Python 3.6+, the SHA3 is available in hashlib natively. Else this requires
+# the pysha3 package (pip install pysha3).
+if sys.version_info < (3, 6):
+    import sha3
+
+# Test vector to make sure the right sha3 version will be used. pysha3 < 1.0
+# used the old Keccak implementation. During the finalization of SHA3, NIST
+# changed the delimiter suffix from 0x01 to 0x06. The Keccak sponge function
+# stayed the same. pysha3 1.0 provides the previous Keccak hash, too.
+TEST_VALUE = "e167f68d6563d75bb25f3aa49c29ef612d41352dc00606de7cbd630bb2665f51"
+if TEST_VALUE != sha3.sha3_256(b"Hello World").hexdigest():
+    print("pysha3 version is < 1.0. Please install from:")
+    print("https://github.com/tiran/pysha3https://github.com/tiran/pysha3")
+    sys.exit(1)
+
+# Checksum is built like so:
+#   CHECKSUM = SHA3(".onion checksum" || PUBKEY || VERSION)
+PREFIX = ".onion checksum".encode()
+# 32 bytes ed25519 pubkey.
+PUBKEY = ("\x42" * 32).encode()
+# Version 3 is proposal224
+VERSION = 3
+
+data = struct.pack('15s32sb', PREFIX, PUBKEY, VERSION)
+checksum = hashlib.sha3_256(data).digest()
+
+# Onion address is built like so:
+#   onion_address = base32(PUBKEY || CHECKSUM || VERSION) + ".onion"
+address = struct.pack('!32s2sb', PUBKEY, checksum, VERSION)
+onion_addr = base64.b32encode(address).decode().lower()
+
+print("%s" % (onion_addr))
diff --git a/src/test/test_hs_service.c b/src/test/test_hs_service.c
index 17772f1df0..e081b7f2f3 100644
--- a/src/test/test_hs_service.c
+++ b/src/test/test_hs_service.c
@@ -207,6 +207,85 @@ test_hs_ntor(void *arg)
   tt_mem_op(client_hs_ntor_rend_cell_keys.ntor_key_seed, OP_EQ,
             service_hs_ntor_rend_cell_keys.ntor_key_seed,
             DIGEST256_LEN);
+ done:
+  ;
+}
+
+static void
+test_validate_address(void *arg)
+{
+  int ret;
+
+  (void) arg;
+
+  /* Address too short and too long. */
+  setup_full_capture_of_logs(LOG_WARN);
+  ret = hs_address_is_valid("blah");
+  tt_int_op(ret, OP_EQ, 0);
+  expect_log_msg_containing("has an invalid length");
+  teardown_capture_of_logs();
+
+  setup_full_capture_of_logs(LOG_WARN);
+  ret = hs_address_is_valid(
+           "p3xnclpu4mu22dwaurjtsybyqk4xfjmcfz6z62yl24uwmhjatiwnlnadb");
+  tt_int_op(ret, OP_EQ, 0);
+  expect_log_msg_containing("has an invalid length");
+  teardown_capture_of_logs();
+
+  /* Invalid checksum (taken from prop224) */
+  setup_full_capture_of_logs(LOG_WARN);
+  ret = hs_address_is_valid(
+           "l5satjgud6gucryazcyvyvhuxhr74u6ygigiuyixe3a6ysis67ororad");
+  tt_int_op(ret, OP_EQ, 0);
+  expect_log_msg_containing("invalid checksum");
+  teardown_capture_of_logs();
+
+  setup_full_capture_of_logs(LOG_WARN);
+  ret = hs_address_is_valid(
+           "btojiu7nu5y5iwut64eufevogqdw4wmqzugnoluw232r4t3ecsfv37ad");
+  tt_int_op(ret, OP_EQ, 0);
+  expect_log_msg_containing("invalid checksum");
+  teardown_capture_of_logs();
+
+  /* Non base32 decodable string. */
+  setup_full_capture_of_logs(LOG_WARN);
+  ret = hs_address_is_valid(
+           "????????????????????????????????????????????????????????");
+  tt_int_op(ret, OP_EQ, 0);
+  expect_log_msg_containing("can't be decoded");
+  teardown_capture_of_logs();
+
+  /* Valid address. */
+  ret = hs_address_is_valid(
+           "p3xnclpu4mu22dwaurjtsybyqk4xfjmcfz6z62yl24uwmhjatiwnlnad");
+  tt_int_op(ret, OP_EQ, 1);
+
+ done:
+  ;
+}
+
+static void
+test_build_address(void *arg)
+{
+  int ret;
+  char onion_addr[HS_SERVICE_ADDR_LEN_BASE32 + 1];
+  ed25519_public_key_t pubkey;
+
+  (void) arg;
+
+  /* The following has been created with hs_build_address.py script that
+   * follows proposal 224 specification to build an onion address. */
+  static const char *test_addr =
+    "ijbeeqscijbeeqscijbeeqscijbeeqscijbeeqscijbeeqscijbezhid";
+
+  /* Let's try to build the same onion address that the script can do. Key is
+   * a long set of very random \x42 :). */
+  memset(&pubkey, '\x42', sizeof(pubkey));
+  hs_build_address(&pubkey, HS_VERSION_THREE, onion_addr);
+  tt_str_op(test_addr, OP_EQ, onion_addr);
+  /* Validate that address. */
+  ret = hs_address_is_valid(onion_addr);
+  tt_int_op(ret, OP_EQ, 1);
 
  done:
   ;
@@ -326,6 +405,10 @@ struct testcase_t hs_service_tests[] = {
     NULL, NULL },
   { "e2e_rend_circuit_setup", test_e2e_rend_circuit_setup, TT_FORK,
     NULL, NULL },
+  { "build_address", test_build_address, TT_FORK,
+    NULL, NULL },
+  { "validate_address", test_validate_address, TT_FORK,
+    NULL, NULL },
 
   END_OF_TESTCASES
 };