Struct Addr

pub struct Addr;

The Address attribute indicates a reflexive transport address of the client. It consists of an 8-bit address family and a 16-bit port, followed by a fixed-length value representing the IP address. If the address family is IPv4, the address MUST be 32 bits. If the address family is IPv6, the address MUST be 128 bits. All fields must be in network byte order.

The format of the MAPPED-ADDRESS attribute is:

0                   1                   2                   3
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 0 0 0 0 0|    Family     |           Port                |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                                                               |
|                 Address (32 bits or 128 bits)                 |
|                                                               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 5: Format of MAPPED-ADDRESS Attribute

The address family can take on the following values:

• 0x01:IPv4
• 0x02:IPv6

The first 8 bits of the MAPPED-ADDRESS MUST be set to 0 and MUST be ignored by receivers. These bits are present for aligning parameters on natural 32-bit boundaries.

This attribute is used only by servers for achieving backwards compatibility with RFC3489 clients.

The XOR-MAPPED-ADDRESS attribute is identical to the MAPPED-ADDRESS attribute, except that the reflexive transport address is obfuscated through the XOR function.

The format of the XOR-MAPPED-ADDRESS is:

0                   1                   2                   3
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 0 0 0 0 0|    Family     |         X-Port                |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                X-Address (Variable)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

         Figure 6: Format of XOR-MAPPED-ADDRESS Attribute

The Family field represents the IP address family and is encoded identically to the Family field in MAPPED-ADDRESS.

X-Port is computed by XOR’ing the mapped port with the most significant 16 bits of the magic cookie. If the IP address family is IPv4, X-Address is computed by XOR’ing the mapped IP address with the magic cookie. If the IP address family is IPv6, X-Address is computed by XOR’ing the mapped IP address with the concatenation of the magic cookie and the 96-bit transaction ID. In all cases, the XOR operation works on its inputs in network byte order (that is, the order they will be encoded in the message).

The rules for encoding and processing the first 8 bits of the attribute’s value, the rules for handling multiple occurrences of the attribute, and the rules for processing address families are the same as for MAPPED-ADDRESS.

Note: XOR-MAPPED-ADDRESS and MAPPED-ADDRESS differ only in their encoding of the transport address. The former encodes the transport address by XOR’ing it with the magic cookie. The latter encodes it directly in binary. RFC3489 originally specified only MAPPED- ADDRESS. However, deployment experience found that some NATs rewrite the 32-bit binary payloads containing the NAT’s public IP address, such as STUN’s MAPPED-ADDRESS attribute, in the well-meaning but misguided attempt to provide a generic Application Layer Gateway (ALG) function. Such behavior interferes with the operation of STUN and also causes failure of STUN’s message-integrity checking.

Implementations

impl Addr

pub fn into(a: &SocketAddr, token: &[u8], buf: &mut BytesMut, is_xor: bool)

encoder SocketAddr as Bytes.

Unit Test

use bytes::BytesMut;
use faster_stun::attribute::*;

let xor_addr_buf: [u8; 8] =
    [0x00, 0x01, 0xfc, 0xbe, 0xe1, 0xba, 0xa4, 0x29];

let addr_buf: [u8; 8] = [0x00, 0x01, 0xdd, 0xac, 0xc0, 0xa8, 0x00, 0x6b];

let token: [u8; 12] = [
    0x6c, 0x46, 0x62, 0x54, 0x75, 0x4b, 0x44, 0x51, 0x46, 0x48, 0x4c, 0x71,
];

let source = "192.168.0.107:56748".parse().unwrap();

let mut buffer = BytesMut::with_capacity(1280);
Addr::into(&source, &token, &mut buffer, true);
assert_eq!(&xor_addr_buf, &buffer[..]);

let mut buffer = BytesMut::with_capacity(1280);
Addr::into(&source, &token, &mut buffer, false);
assert_eq!(&addr_buf, &buffer[..]);

pub fn try_from( packet: &[u8], token: &[u8], is_xor: bool, ) -> Result<SocketAddr, StunError>

decoder Bytes as SocketAddr.

Unit Test

use faster_stun::attribute::*;

let xor_addr_buf: [u8; 8] =
    [0x00, 0x01, 0xfc, 0xbe, 0xe1, 0xba, 0xa4, 0x29];

let addr_buf: [u8; 8] = [0x00, 0x01, 0xdd, 0xac, 0xc0, 0xa8, 0x00, 0x6b];

let token: [u8; 12] = [
    0x6c, 0x46, 0x62, 0x54, 0x75, 0x4b, 0x44, 0x51, 0x46, 0x48, 0x4c, 0x71,
];

let source = "192.168.0.107:56748".parse().unwrap();

let addr = Addr::try_from(&xor_addr_buf, &token, true).unwrap();
assert_eq!(addr, source);

let addr = Addr::try_from(&addr_buf, &token, false).unwrap();
assert_eq!(addr, source);