String To Netstring Converter

Understanding netstring

A netstring is a formatting method for byte strings that uses a declarative notation to indicate the size of the string. A netstring is a self-delimiting encoding of a string. Netstrings are very easy to generate and to parse. Any string may be encoded as a netstring; there are no restrictions on length or on allowed bytes. Another virtue of a netstring is that it declares the string size up front. Thus an application can check in advance whether it has enough space to store the entire string.

The text "hello world!" encodes as : 5:hello,6:world!,

The format consists of the string's length written using ASCII digits, followed by a colon, the byte data, and a comma. "Length" in this context means "number of 8-bit units", so if the string is, for example, encoded using UTF-8, this may or may not be identical to the number of textual characters that are present in the string.

The comma makes it slightly simpler for humans to read netstrings that are used as adjacent records, and provides weak verification of correct parsing. Note that without the comma, the format mirrors how Bencode encodes strings.

The length is written without leading zeroes. Empty string is the only netstring that begins with zero. There is exactly one legal netstring encoding for any byte string.

Netstrings can be stored recursively. The result of encoding a sequence of strings is a single string. Rewriting the above "hello world!" example to instead be a sequence of two netstrings, itself encoded as a single netstring, gives the following:

17:5:hello,6:world!,

A detailed description can be found here.