CODEWITHSUNDEEP
c#jsonbase64
Reynevan
Reynevan

Reputation: 1545

How do I decode message.parts returned by GMail API?

I'm using Gmail API to get some messages from the server. It returns a long json array. Here's the relevant part:

"parts": [
   {
    "partId": "0",
    "mimeType": "text/plain",
    "filename": "",
    "headers": [
     {
      "name": "Content-Type",
      "value": "text/plain; charset=UTF-8"
     }
    ],
    "body": {
     "size": 91,
     "data": "dGVzdA0KLS0NCkRhd2lkIChSZXluZXZhbikgU2VyYWZpbg0KKmh0dHA6Ly93d3cucmV5bmV2YW4uY29tLyA8aHR0cDovL3d3dy5yZXluZXZhbi5jb20vPioNCg=="
    }
   },
   {
    "partId": "1",
    "mimeType": "text/html",
    "filename": "",
    "headers": [
     {
      "name": "Content-Type",
      "value": "text/html; charset=UTF-8"
     },
     {
      "name": "Content-Transfer-Encoding",
      "value": "quoted-printable"
     }
    ],
    "body": {
     "size": 391,
     "data": "PGRpdiBkaXI9Imx0ciI-dGVzdDxiciBjbGVhcj0iYWxsIj48ZGl2PjxkaXYgY2xhc3M9ImdtYWlsX3NpZ25hdHVyZSI-PGRpdiBkaXI9Imx0ciI-PGRpdj48Zm9udCBmYWNlPSJjb21pYyBzYW5zIG1zLCBzYW5zLXNlcmlmIj4tLTwvZm9udD48L2Rpdj48Zm9udCBmYWNlPSJjb21pYyBzYW5zIG1zLCBzYW5zLXNlcmlmIj5EYXdpZCAoUmV5bmV2YW4pIFNlcmFmaW48L2ZvbnQ-PGRpdj48Zm9udCBmYWNlPSJjb21pYyBzYW5zIG1zLCBzYW5zLXNlcmlmIj48Yj48aT48YSBocmVmPSJodHRwOi8vd3d3LnJleW5ldmFuLmNvbS8iIHRhcmdldD0iX2JsYW5rIj5odHRwOi8vd3d3LnJleW5ldmFuLmNvbS88L2E-PC9pPjwvYj48L2ZvbnQ-PC9kaXY-PC9kaXY-PC9kaXY-PC9kaXY-DQo8L2Rpdj4NCg=="
    }
   }
  ]

The first one I can parse without problem using this code:

foreach (Match b in body)
{
    var raw = b.Groups[1].Value;
    var bytes = Convert.FromBase64String(raw);
    var s = Encoding.UTF8.GetString(bytes);
    bodyDecoded += s;
}

but the second one looks different than the first and this code throws a FormatException.

What should I do? Is this still base64? Should I remove the dashes maybe?

Edit: Here's another string: 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

EDIT by eser

And this is what my code in the answer produces(filtered)

XXXXXX, the XXXXXX 1 V SP 'Patch' has dropped – here's your purchase
link.
<https://launches.XXXXXXXX.com/>
XXXXXX 1 V SP 'Patch'

Sand
[image: Product image]

DROPS IN

*00* days : *00* hrs : *00* mins : *00* secs

Please click the link below to join the queue for purchasing this product.
Remember to hurry - stock is allocated on a first come first serve basis.
Clicking this link does not guarantee purchase.
Click Here
<https://launches.XXXXXXX.com/#/checkout/XXXX/login>
END.
XXXXXXXXXXXXXXXXXXXXXx
XXXXXXXXXXXXXXXXXXXX
NE27 0QG
+44 (0)XXX XXX XXXX
[email protected]
[image: Facebook] [image: Google+] [image: Instagram] [image: Twitter]

Upvotes: 2

Views: 3288

Answers (2)

rtev
rtev

Reputation: 1122

The Google Gmail API works with a variant of Base64 encoding which is safe for use in URLs. This scheme substitutes '-' characters for '+' characters, substitutes '/' characters for '_' characters and removes any trailing '=' characters padding the end of the string.

Please see the following question for details and conversion code: How to achieve Base64 URL safe encoding in C#?

Upvotes: 0

Eser
Eser

Reputation: 12546

- is not a valid base64 char... I don't know the reason to use that char, but just replace - with + and you'll get the correct html..

string data = "PGRpdiBkaXI9Imx0ciI-dGVzdDxiciBjbGVhcj0iYWxsIj48ZGl2PjxkaXYgY2xhc3M9ImdtYWlsX3NpZ25hdHVyZSI-PGRpdiBkaXI9Imx0ciI-PGRpdj48Zm9udCBmYWNlPSJjb21pYyBzYW5zIG1zLCBzYW5zLXNlcmlmIj4tLTwvZm9udD48L2Rpdj48Zm9udCBmYWNlPSJjb21pYyBzYW5zIG1zLCBzYW5zLXNlcmlmIj5EYXdpZCAoUmV5bmV2YW4pIFNlcmFmaW48L2ZvbnQ-PGRpdj48Zm9udCBmYWNlPSJjb21pYyBzYW5zIG1zLCBzYW5zLXNlcmlmIj48Yj48aT48YSBocmVmPSJodHRwOi8vd3d3LnJleW5ldmFuLmNvbS8iIHRhcmdldD0iX2JsYW5rIj5odHRwOi8vd3d3LnJleW5ldmFuLmNvbS88L2E-PC9pPjwvYj48L2ZvbnQ-PC9kaXY-PC9kaXY-PC9kaXY-PC9kaXY-DQo8L2Rpdj4NCg==";

var base64 = Convert.FromBase64String(data.Replace("-", "+"));
var str = Encoding.UTF8.GetString(base64);

Result:

<div dir="ltr">test<br clear="all"><div><div class="gmail_signature"><div dir="ltr"><div><font face="comic sans ms, sans-serif">--</font></div><font face="comic sans ms, sans-serif">Dawid (Reynevan) Serafin</font><div><font face="comic sans ms, sans-serif"><b><i><a href="http://www.reynevan.com/" target="_blank">http://www.reynevan.com/</a></i></b></font></div></div></div></div> </div>

Upvotes: 2

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