feat: print TXT record values quoted, matching dig

README.md

@@ -262,6 +262,29 @@ Run `tdig --help` for the in-binary reference.
 | TCP forcing | `+tcp` | `--tcp` |
 | Reverse lookup | `-x` | `-x` |
 | Packet I/O | external tools | **Built-in `--read` / `--write`** |
+| Multi-string TXT | `"abc" "def"` | `"abcdef"` (concatenated) |
+
+### Known difference: multi-string TXT records
+
+A TXT record's RDATA is a list of character-strings, and values longer than 255
+bytes (DKIM keys, long SPF records) are always split across several of them.
+`dig` prints each one separately:
+
+```
+example.com.  300  IN  TXT  "abc" "def"
+```
+
+`tdig` prints their concatenation as a single quoted value instead:
+
+```
+example.com.  300  IN  TXT  "abcdef"
+```
+
+**No data is lost** — the full value is shown, only the string boundaries are
+not. This follows [`tenbin_dns`](https://github.com/smkwlab/tenbin_dns), which
+returns the concatenation as the record's logical value (matching how SPF
+treats multi-string TXT per RFC 7208 §3.3) and deliberately does not preserve
+boundaries.
 
 If you already have BIND's `dig`, you don't need `tdig`. It's useful when:
 

lib/tdig.ex

@@ -267,7 +267,7 @@ defmodule Tdig do
   def rdata_to_string(rdata, :ns), do: escape(rdata.name)
   def rdata_to_string(rdata, :ptr), do: escape(rdata.name)
   def rdata_to_string(rdata, :cname), do: escape(rdata.name)
-  def rdata_to_string(rdata, :txt), do: escape(rdata.txt)
+  def rdata_to_string(rdata, :txt), do: quote_character_string(rdata.txt)
   def rdata_to_string(rdata, :mx), do: "#{rdata.preference} #{escape(rdata.name)}"
 
   def rdata_to_string(rdata, :caa),
@@ -296,6 +296,23 @@ defmodule Tdig do
   defp escape_byte(byte) when byte in 0x20..0x7E, do: <<byte>>
   defp escape_byte(byte), do: "\\" <> String.pad_leading(Integer.to_string(byte), 3, "0")
 
+  # Render a TXT character-string the way dig does: wrapped in double quotes,
+  # with `"` escaped on top of the shared escaping above. Domain names go
+  # through escape/1 instead — dig leaves those unquoted, so the quoting must
+  # not be folded into escape_byte/1.
+  #
+  # tenbin_dns returns the concatenation of a TXT record's character-strings
+  # as one binary (boundaries are deliberately not preserved, see
+  # smkwlab/tenbin_dns#95), so a multi-string record prints as a single quoted
+  # value where dig prints `"abc" "def"`. The value itself is complete.
+  defp quote_character_string(string) when is_binary(string) do
+    escaped = for <<byte <- string>>, into: "", do: escape_character_string_byte(byte)
+    <<?", escaped::binary, ?">>
+  end
+
+  defp escape_character_string_byte(?"), do: "\\\""
+  defp escape_character_string_byte(byte), do: escape_byte(byte)
+
   def disp_tailer(server, port, size, time) do
     # Get system local time using NaiveDateTime (OS-independent, cleaner)
     now = NaiveDateTime.local_now() |> NaiveDateTime.to_string()

test/tdig_test.exs

@@ -246,7 +246,39 @@ defmodule TdigTest do
 
     test "rdata_to_string formats TXT records" do
       rdata = %{txt: "v=spf1 include:_spf.google.com ~all"}
-      assert Tdig.rdata_to_string(rdata, :txt) == "v=spf1 include:_spf.google.com ~all"
+      assert Tdig.rdata_to_string(rdata, :txt) == ~s("v=spf1 include:_spf.google.com ~all")
+    end
+
+    test "rdata_to_string escapes double quotes inside TXT records" do
+      rdata = %{txt: ~s(a"b)}
+      assert Tdig.rdata_to_string(rdata, :txt) == ~S("a\"b")
+    end
+
+    test "rdata_to_string escapes backslashes inside TXT records" do
+      rdata = %{txt: ~S(a\b)}
+      assert Tdig.rdata_to_string(rdata, :txt) == ~S("a\\b")
+    end
+
+    test "rdata_to_string escapes non-printable bytes inside TXT records" do
+      # Terminal escape sequences must not survive into the output; dig renders
+      # non-printable octets as three-digit decimal escapes.
+      rdata = %{txt: <<0x1B, "[31m">>}
+      assert Tdig.rdata_to_string(rdata, :txt) == ~S("\027[31m")
+    end
+
+    test "rdata_to_string renders an empty TXT record as empty quotes" do
+      rdata = %{txt: ""}
+      assert Tdig.rdata_to_string(rdata, :txt) == ~s("")
+    end
+
+    test "rdata_to_string leaves domain names unquoted" do
+      # dig quotes TXT character-strings but not domain names; the TXT-specific
+      # quoting must not leak into the shared escape/1 path.
+      assert Tdig.rdata_to_string(%{name: "ns1.example.com"}, :ns) == "ns1.example.com"
+      assert Tdig.rdata_to_string(%{name: "alias.example.com"}, :cname) == "alias.example.com"
+
+      assert Tdig.rdata_to_string(%{preference: 10, name: "mail.example.com"}, :mx) ==
+               "10 mail.example.com"
     end
 
     test "rdata_to_string handles unknown types" do
@@ -363,7 +395,9 @@ defmodule TdigTest do
     end
 
     test "rdata_to_string escapes untrusted TXT and name bytes" do
-      assert Tdig.rdata_to_string(%{txt: <<"hi", 0x1B, "!">>}, :txt) == "hi\\027!"
+      # TXT is additionally wrapped in quotes to match dig; the escaping of the
+      # ESC byte is what matters here.
+      assert Tdig.rdata_to_string(%{txt: <<"hi", 0x1B, "!">>}, :txt) == ~S("hi\027!")
 
       assert Tdig.rdata_to_string(%{name: <<"ns", 0x1B, ".example.">>}, :cname) ==
                "ns\\027.example."