stun-bytes

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A low-level base for STUN message protocol parsers.

Highlights

STUN Message structure

Header

text 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Message Type (16 bits) | Message Length (16 bits) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Magic Cookie (32 bits) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | Transaction ID (96 bits) | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Note: since RFC5389, Transaction ID field has been split into Magic Cookie and Transaction ID. If you want to follow this split, enable the cookie feature.

Attribute

text 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type (16 bits) | Length (16 bits) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Value (variable) .. +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Examples

Parse STUN message

```rust const MSG: [u8; 28] = [ 0x00, 0x01, // type: Binding Request 0x00, 0x08, // length: 8 (header does not count) 0x21, 0x12, 0xA4, 0x42, // magic cookie 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, // transaction id 0x00, 0x03, // type: ChangeRequest 0x00, 0x04, // length: 4 (only value bytes count) 0x00, 0x00, 0x00, 0x40 | 0x20, // change both ip and port ];

let msg = ByteMsg::from_arr(&MSG);

asserteq!(&MSG[0..2], msg.typ()?); // read type field asserteq!(&MSG[2..4], msg.len()?); // read length field asserteq!(&MSG[4..8], msg.cookie()?); // read cookie field (enable 'cookie' feature first) asserteq!(&MSG[8..20], msg.tid()?); // read transaction id field assert_eq!(&MSG[20..28], msg.attrs()?); // read all attribute bytes

let attr = msg.attrs_iter().next()?; // iterate over attributes

asserteq!(&MSG[20..22], attr.typ()?); // read attribute type field asserteq!(&MSG[22..24], attr.len()?); // read attribute length field assert_eq!(&MSG[24..28], attr.val()?); // read attribute value field ```

Create STUN message

```rust const MSG: [u8; 28] = [ 0x00, 0x01, // type: Binding Request 0x00, 0x08, // length: 8 (header does not count) 0x21, 0x12, 0xA4, 0x42, // magic cookie 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, // transaction id 0x00, 0x03, // type: ChangeRequest 0x00, 0x04, // length: 4 (only value bytes count) 0x00, 0x00, 0x00, 0x40 | 0x20, // change both ip and port ];

let mut buf = [0u8; MSG.len()]; let mut msg = ByteMsgMut::fromarrmut(&mut buf);

msg.typ()?.copyfrom(MSG.carved()?); // write type field // msg.len()?.copyfrom(MSG.carve(2)?); // length field updates automatically msg.cookie()?.copyfrom(MSG.carve(4)?); // write cookie field msg.tid()?.copyfrom(MSG.carve(8)?); // write transaction id field msg.add_attr(MSG.carve(20)?, MSG.carve(22)?, MSG.get(24..28)?); // write attribute (type, length, value)

asserteq!(&MSG, msg.asbytes()); ```

Contribution guidelines

Pull requests are welcome. Please make sure your contribution adheres to the Principles section above.