xenet_packet/
gre.rs

1//! GRE Packet abstraction.
2
3#[cfg(test)]
4use crate::Packet;
5
6use alloc::vec::Vec;
7
8use xenet_macro::packet;
9use xenet_macro_helper::types::*;
10
11/// GRE (Generic Routing Encapsulation) Packet.
12///
13/// See RFCs 1701, 2784, 2890, 7676, 2637
14#[packet]
15pub struct Gre {
16    pub checksum_present: u1,
17    pub routing_present: u1,
18    pub key_present: u1,
19    pub sequence_present: u1,
20    pub strict_source_route: u1,
21    pub recursion_control: u3,
22    pub zero_flags: u5,
23    pub version: u3,
24    pub protocol_type: u16be, // 0x800 for ipv4 [basically an ethertype
25    #[length_fn = "gre_checksum_length"]
26    pub checksum: Vec<U16BE>,
27    #[length_fn = "gre_offset_length"]
28    pub offset: Vec<U16BE>,
29    #[length_fn = "gre_key_length"]
30    pub key: Vec<U32BE>,
31    #[length_fn = "gre_sequence_length"]
32    pub sequence: Vec<U32BE>,
33    #[length_fn = "gre_routing_length"]
34    pub routing: Vec<u8>,
35    #[payload]
36    pub payload: Vec<u8>,
37}
38
39fn gre_checksum_length(gre: &GrePacket) -> usize {
40    (gre.get_checksum_present() | gre.get_routing_present()) as usize * 2
41}
42
43fn gre_offset_length(gre: &GrePacket) -> usize {
44    (gre.get_checksum_present() | gre.get_routing_present()) as usize * 2
45}
46
47fn gre_key_length(gre: &GrePacket) -> usize {
48    gre.get_key_present() as usize * 4
49}
50
51fn gre_sequence_length(gre: &GrePacket) -> usize {
52    gre.get_sequence_present() as usize * 4
53}
54
55fn gre_routing_length(gre: &GrePacket) -> usize {
56    if 0 == gre.get_routing_present() {
57        0
58    } else {
59        panic!("Source routed GRE packets not supported")
60    }
61}
62
63/// `u16be`, but we can't use that directly in a `Vec` :(
64#[packet]
65pub struct U16BE {
66    number: u16be,
67    #[length = "0"]
68    #[payload]
69    unused: Vec<u8>,
70}
71
72/// `u32be`, but we can't use that directly in a `Vec` :(
73#[packet]
74pub struct U32BE {
75    number: u32be,
76    #[length = "0"]
77    #[payload]
78    unused: Vec<u8>,
79}
80
81#[test]
82fn gre_packet_test() {
83    let mut packet = [0u8; 4];
84    {
85        let mut gre_packet = MutableGrePacket::new(&mut packet[..]).unwrap();
86        gre_packet.set_protocol_type(0x0800);
87        assert_eq!(gre_packet.payload().len(), 0);
88    }
89
90    let ref_packet = [
91        0x00, /* no flags */
92        0x00, /* no flags, version 0 */
93        0x08, /* protocol 0x0800 */
94        0x00,
95    ];
96
97    assert_eq!(&ref_packet[..], &packet[..]);
98}
99
100#[test]
101fn gre_checksum_test() {
102    let mut packet = [0u8; 8];
103    {
104        let mut gre_packet = MutableGrePacket::new(&mut packet[..]).unwrap();
105        gre_packet.set_checksum_present(1);
106        assert_eq!(gre_packet.payload().len(), 0);
107        assert_eq!(gre_packet.get_checksum().len(), 1);
108        assert_eq!(gre_packet.get_offset().len(), 1);
109    }
110
111    let ref_packet = [
112        0x80, /* checksum on */
113        0x00, /* no flags, version 0 */
114        0x00, /* protocol 0x0000 */
115        0x00, 0x00, /* 16 bits of checksum */
116        0x00, 0x00, /* 16 bits of offset */
117        0x00,
118    ];
119
120    assert_eq!(&ref_packet[..], &packet[..]);
121}
xenet_packet/gre.rs

xenet_packet/
gre.rs
