add test for checking implementations

README.md

@@ -51,3 +51,71 @@ var myTransform = Packer.Transform.create({
 , service: 'https'
 });
 ```
+
+# Testing an implementation
+
+If you want to write a compatible packer, just make sure that for any given input
+you get the same output as the packer does.
+
+```bash
+node test-pack.js input.json output.bin
+hexdump output.bin
+```
+
+Where `input.json` looks something like this:
+
+`input.json`:
+```
+{ "version": 1
+, "address": {
+    "family": "IPv4"
+  , "address": "127.0.1.1"
+  , "port": 443
+  , "service": "foo"
+  }
+, "filepath": "./sni.tcp.bin"
+}
+```
+
+and `sni.tcp.bin` is any captured tcp packet, such as this one with a tls hello:
+
+`sni.tcp.bin`:
+```
+0000000 16 03 01 00 c2 01 00 00 be 03 03 57 e3 76 50 66
+0000010 03 df 99 76 24 c8 31 e6 e8 08 34 6b b4 7b bb 2c
+0000020 f3 17 aa 5c ec 09 da da 83 5a b2 00 00 56 00 ff
+0000030 c0 24 c0 23 c0 0a c0 09 c0 08 c0 28 c0 27 c0 14
+0000040 c0 13 c0 12 c0 26 c0 25 c0 05 c0 04 c0 03 c0 2a
+0000050 c0 29 c0 0f c0 0e c0 0d 00 6b 00 67 00 39 00 33
+0000060 00 16 00 3d 00 3c 00 35 00 2f 00 0a c0 07 c0 11
+0000070 c0 02 c0 0c 00 05 00 04 00 af 00 ae 00 8d 00 8c
+0000080 00 8a 00 8b 01 00 00 3f 00 00 00 19 00 17 00 00
+0000090 14 70 6f 6b 65 6d 61 70 2e 68 65 6c 6c 61 62 69
+00000a0 74 2e 63 6f 6d 00 0a 00 08 00 06 00 17 00 18 00
+00000b0 19 00 0b 00 02 01 00 00 0d 00 0c 00 0a 05 01 04
+00000c0 01 02 01 04 03 02 03
+00000c7
+```
+
+You should see that the result is simply all of the original packet with a leading header.
+
+Note that `16 03 01 00` starts at the 29th byte (at index 28 or 0x1C) instead of at index 0:
+
+```
+0000000 fe 1a 49 50 76 34 2c 31 32 37 2e 30 2e 31 2e 31 <-- 0xfe = v1, 0x1a = 26 more bytes for header
+0000010 2c 34 34 33 2c 31 39 39 2c 66 6f 6f 16 03 01 00 <-- first 4 bytes of tcp packet
+0000020 c2 01 00 00 be 03 03 57 e3 76 50 66 03 df 99 76
+0000030 24 c8 31 e6 e8 08 34 6b b4 7b bb 2c f3 17 aa 5c
+0000040 ec 09 da da 83 5a b2 00 00 56 00 ff c0 24 c0 23
+0000050 c0 0a c0 09 c0 08 c0 28 c0 27 c0 14 c0 13 c0 12
+0000060 c0 26 c0 25 c0 05 c0 04 c0 03 c0 2a c0 29 c0 0f
+0000070 c0 0e c0 0d 00 6b 00 67 00 39 00 33 00 16 00 3d
+0000080 00 3c 00 35 00 2f 00 0a c0 07 c0 11 c0 02 c0 0c
+0000090 00 05 00 04 00 af 00 ae 00 8d 00 8c 00 8a 00 8b
+00000a0 01 00 00 3f 00 00 00 19 00 17 00 00 14 70 6f 6b
+00000b0 65 6d 61 70 2e 68 65 6c 6c 61 62 69 74 2e 63 6f
+00000c0 6d 00 0a 00 08 00 06 00 17 00 18 00 19 00 0b 00
+00000d0 02 01 00 00 0d 00 0c 00 0a 05 01 04 01 02 01 04
+00000e0 03 02 03
+00000e3
+```

input.json

@@ -0,0 +1,9 @@
+{ "version": 1
+, "address": {
+    "family": "IPv4"
+  , "address": "127.0.1.1"
+  , "port": 443
+  , "service": "foo"
+  }
+, "filepath": "./sni.hello.bin"
+}

output.hexdump

@@ -0,0 +1,16 @@
+0000000 fe 1a 49 50 76 34 2c 31 32 37 2e 30 2e 31 2e 31
+0000010 2c 34 34 33 2c 31 39 39 2c 66 6f 6f 16 03 01 00
+0000020 c2 01 00 00 be 03 03 57 e3 76 50 66 03 df 99 76
+0000030 24 c8 31 e6 e8 08 34 6b b4 7b bb 2c f3 17 aa 5c
+0000040 ec 09 da da 83 5a b2 00 00 56 00 ff c0 24 c0 23
+0000050 c0 0a c0 09 c0 08 c0 28 c0 27 c0 14 c0 13 c0 12
+0000060 c0 26 c0 25 c0 05 c0 04 c0 03 c0 2a c0 29 c0 0f
+0000070 c0 0e c0 0d 00 6b 00 67 00 39 00 33 00 16 00 3d
+0000080 00 3c 00 35 00 2f 00 0a c0 07 c0 11 c0 02 c0 0c
+0000090 00 05 00 04 00 af 00 ae 00 8d 00 8c 00 8a 00 8b
+00000a0 01 00 00 3f 00 00 00 19 00 17 00 00 14 70 6f 6b
+00000b0 65 6d 61 70 2e 68 65 6c 6c 61 62 69 74 2e 63 6f
+00000c0 6d 00 0a 00 08 00 06 00 17 00 18 00 19 00 0b 00
+00000d0 02 01 00 00 0d 00 0c 00 0a 05 01 04 01 02 01 04
+00000e0 03 02 03
+00000e3

test-pack.js

@@ -0,0 +1,32 @@
+;(function () {
+'use strict';
+
+var fs = require('fs');
+var infile = process.argv[2];
+var outfile = process.argv[3];
+
+if (!infile || !outfile) {
+  console.error("Usage:");
+  console.error("node test-pack.js input.json output.bin");
+  process.exit(1);
+  return;
+}
+
+var json = JSON.parse(fs.readFileSync(infile, 'utf8'));
+var version = json.version;
+var address = json.address;
+var data = require('fs').readFileSync(json.filepath, null);
+
+var header = address.family + ',' + address.address + ',' + address.port + ',' + data.byteLength
+  + ',' + (address.service || '')
+  ;
+var buf = Buffer.concat([
+  Buffer.from([ 255 - version, header.length ])
+, Buffer.from(header)
+, data
+]);
+
+fs.writeFileSync(outfile, buf, null);
+console.log("wrote " + buf.byteLength + " bytes to '" + outfile + "' ('hexdump " + outfile + "' to inspect)");
+
+}());