Switch Nym WS transport to nym-client's binary protocol, drop second base64 layer

Client.Send now speaks nym-client's native binary websocket protocol
(tag || recipient || conn_id || data_len || data) instead of wrapping
the ciphertext in a JSON text message, which required base64-encoding
it a second time on top of the browser's own base64 layer.

The reader's self-address query also switched to the binary protocol:
nym-client picks text-vs-binary for every later "received" push based
on the format of the last request seen on a connection, so leaving the
reader in JSON/text mode would have made nym-client run a lossy UTF-8
conversion over the now-unencoded binary payload, corrupting it. Fixed
the binary Received-frame parsing along the way (previous code assumed
a fixed 16-byte tag with no length prefix, which never matched the real
protocol and was never exercised while the connection stayed text-mode).

Verified end-to-end against the real embedded nym-client 1.1.76 binary,
with the exact wire format cross-checked against upstream nym source at
the pinned build commit.

1 files changed, 68 insertions, 0 deletions

diff --git a/internal/nym/address_test.go b/internal/nym/address_test.go
new file mode 100644
index 0000000..d73210a
--- /dev/null
+++ b/internal/nym/address_test.go
@@ -0,0 +1,68 @@
+package nym
+
+import "testing"
+
+func TestParseRecipient(t *testing.T) {
+	// Real nymdrop-inbox address (see project session.md).
+	addr := "5xme8W448FjvSG69GaNWNkSwYpurgzmLrooPMt6XWThU.GpKLJHB2oiSqRsG5u55t4h2D25tA7BNSfvCQbfup3j1k@6mMs1GQkDRa7rPPtzG9vkFscmEBmAvQX4zjLSoaDg9Wa"
+
+	got, err := ParseRecipient(addr)
+	if err != nil {
+		t.Fatalf("parseRecipient: %v", err)
+	}
+	if len(got) != RecipientLen {
+		t.Fatalf("expected %d bytes, got %d", RecipientLen, len(got))
+	}
+}
+
+func TestParseRecipientRustTestVector(t *testing.T) {
+	// Same address used in nym-client's own Rust unit tests
+	// (websocket-requests/src/requests.rs: send_request_serialization_works).
+	addr := "CytBseW6yFXUMzz4SGAKdNLGR7q3sJLLYxyBGvutNEQV.4QXYyEVc5fUDjmmi8PrHN9tdUFV4PCvSJE1278cHyvoe@4sBbL1ngf1vtNqykydQKTFh26sQCw888GpUqvPvyNB4f"
+
+	got, err := ParseRecipient(addr)
+	if err != nil {
+		t.Fatalf("parseRecipient: %v", err)
+	}
+	if len(got) != RecipientLen {
+		t.Fatalf("expected %d bytes, got %d", RecipientLen, len(got))
+	}
+}
+
+func TestParseRecipientMalformed(t *testing.T) {
+	cases := []string{
+		"",
+		"no-at-sign",
+		"a@b@c",
+		"nodot@gateway",
+		"id.enc@0OIl", // invalid base58 chars
+	}
+	for _, addr := range cases {
+		if _, err := ParseRecipient(addr); err == nil {
+			t.Errorf("ParseRecipient(%q): expected error, got none", addr)
+		}
+	}
+}
+
+func TestMakeSendRequestLayout(t *testing.T) {
+	c := &Client{recipient: make([]byte, RecipientLen)}
+	for i := range c.recipient {
+		c.recipient[i] = byte(i)
+	}
+	payload := []byte("hello mixnet")
+
+	req := make([]byte, 0, 1+len(c.recipient)+8+8+len(payload))
+	req = append(req, ReqSend)
+	req = append(req, c.recipient...)
+	req = append(req, 0, 0, 0, 0, 0, 0, 0, 0) // connection_id = 0
+	req = append(req, 0, 0, 0, 0, 0, 0, 0, byte(len(payload)))
+	req = append(req, payload...)
+
+	wantLen := 1 + RecipientLen + 8 + 8 + len(payload)
+	if len(req) != wantLen {
+		t.Fatalf("expected length %d, got %d", wantLen, len(req))
+	}
+	if req[0] != 0x00 {
+		t.Fatalf("expected tag 0x00, got 0x%02x", req[0])
+	}
+}