From 4e0a37c0f5d01573724584db0ff7e68e3cdc63f5 Mon Sep 17 00:00:00 2001
From: AJ ONeal <aj@daplie.com>
Date: Mon, 2 Oct 2017 16:43:58 -0600
Subject: [PATCH] check dns0x20 support by default

---
 README.md    |  5 ++++-
 bin/dig.js   | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++--
 package.json |  2 ++
 3 files changed, 58 insertions(+), 3 deletions(-)

diff --git a/README.md b/README.md
index 4763caf..6374fe2 100644
--- a/README.md
+++ b/README.md
@@ -4,7 +4,7 @@ dig.js
 | [dns-suite](https://git.daplie.com/Daplie/dns-suite) | **dig.js** | [digd.js](https://git.daplie.com/Daplie/digd.js) |
 
 Create and capture DNS and mDNS query and response packets to disk as binary and/or JSON.
-Options are similar to the Unix `dig` command.
+Options are similar to the Unix `dig` command. Supports dns0x20 security checking.
 
 Install
 -------
@@ -85,5 +85,8 @@ Options
 +norecurse                  Set `rd` flag to 0. Do not request recursion
 +aaonly                     Set `aa` flag to 1.
 
+--norecase         					Disable dns0x20 security checking (mixed casing). See https://dyn.com/blog/use-of-bit-0x20-in-dns-labels/
+--recase           					Print the dns0x20 casing as-is rather than converting it back to lowercase. This is the default when explicitly using mixed case.
+
 --debug                     verbose output
 ```
diff --git a/bin/dig.js b/bin/dig.js
index bf99fdf..97f97fc 100755
--- a/bin/dig.js
+++ b/bin/dig.js
@@ -22,6 +22,8 @@ cli.parse({
 //, 'serve': [ 's', 'path to json file with array of responses to issue for given queries', 'string' ]
 , 'type': [ 't', 'type (defaults to ANY for dns and PTR for mdns)', 'string' ]
 , 'query': [ 'q', 'a superfluous explicit option to set the query as a command line flag' ]
+, 'norecase': [ false, 'Disable dns0x20 security checking (mixed casing). See https://dyn.com/blog/use-of-bit-0x20-in-dns-labels/' ]
+, 'recase': [ false, "Print the dns0x20 casing as-is rather than converting it back to lowercase. This is the default when explicitly using mixed case." ]
 });
 
 var common = require('../common.js');
@@ -109,6 +111,20 @@ cli.main(function (args, cli) {
     }
   }
 
+  if (cli.query !== cli.query.toLowerCase()) {
+    cli.norecase = true;
+  }
+
+  if (!cli.norecase) {
+    cli.casedQuery = cli.query.split('').map(function (ch) {
+      // dns0x20 takes advantage of the fact that the binary operation for toUpperCase is
+      // ch = ch | 0x20;
+      return Math.round(Math.random()) % 2 ? ch : ch.toUpperCase();
+    }).join('');
+  } else {
+    cli.casedQuery = cli.query;
+  }
+
   if (!cli.type) {
     cli.type = cli.t = 'ANY';
   }
@@ -141,7 +157,7 @@ cli.main(function (args, cli) {
     , rcode: 0                // NA
     }
   , question: [
-      { name: cli.query
+      { name: cli.casedQuery
       , typeName: cli.type
       , className: cli.class
       }
@@ -181,6 +197,40 @@ cli.main(function (args, cli) {
       console.log(packet);
     }
 
+    packet.question.forEach(function (q) {
+      // if (-1 === q.name.indexOf(cli.casedQuery))
+      if (q.name !== cli.casedQuery) {
+        console.log(";; Warning: DNS 0x20 security not implemented (or packet spoofed). Queried '" + cli.casedQuery + "' but got response for '" + q.name + "'.");
+      }
+    });
+    if (!cli.norecase && !cli.recase) {
+      [ 'question', 'answer', 'authority', 'additional' ].forEach(function (group) {
+        (packet[group]||[]).forEach(function (a) {
+          var an = a.name;
+          var i = cli.query.toLowerCase().indexOf(a.name.toLowerCase());  // answer is something like ExAMPle.cOM and query was wWw.ExAMPle.cOM
+          var j = a.name.toLowerCase().indexOf(cli.query.toLowerCase());  // answer is something like www.ExAMPle.cOM and query was ExAMPle.cOM
+
+          // it's important to note that these should only relpace changes in casing that we expected
+          // any abnormalities should be left intact to go "huh?" about
+          // TODO detect abnormalities?
+          if (-1 !== i) {
+            // "EXamPLE.cOm".replace("wWw.EXamPLE.cOm".substr(4), "www.example.com".substr(4))
+            a.name = a.name.replace(cli.casedQuery.substr(i), cli.query.substr(i));
+          } else {
+            // "www.example.com".replace("EXamPLE.cOm", "example.com")
+            a.name = a.name.substr(0, j) + a.name.substr(j).replace(cli.casedQuery, cli.query);
+          }
+
+          // NOTE: right now this assumes that anything matching the query matches all the way to the end
+          // it does not handle the case of a record for example.com.uk being returned in response to a query for www.example.com correctly
+          // (but I don't think it should need to)
+          if (a.name.length !== an.length) {
+            console.error("[ERROR] '" + an + "' != '" + a.length + "'");
+          }
+        });
+      });
+    }
+
     console.log(';; Got answer:');
     dig.logQuestion(packet);
 
@@ -236,7 +286,7 @@ cli.main(function (args, cli) {
 
   console.log('');
   if (!cli.nocmd) {
-    console.log('; <<>> dig.js ' + 'v0.0.0' + ' <<>> ' + process.argv.slice(2).join(' '));
+    console.log('; <<>> dig.js ' + 'v0.0.0' + ' <<>> ' + process.argv.slice(2).join(' ').replace(cli.query, cli.casedQuery));
     console.log(';; global options: +cmd');
   }
 
diff --git a/package.json b/package.json
index be5266f..9525f51 100644
--- a/package.json
+++ b/package.json
@@ -24,6 +24,8 @@
     "dig",
     "dns",
     "mdns",
+    "dns0x20",
+    "0x20",
     "lint",
     "capture",
     "create",