1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
use net::stream::{decode_bytes, decode_u16, decode_u8};
use net::stream::{encode_bytes, encode_u16, encode_u8};
use net::stream::SResult;

#[derive(Copy, Clone, PartialEq)]
pub enum MacAddr {
    ShortAddr(u16),
    LongAddr([u8; 8]),
}

pub mod ip6_nh {
    pub const HOP_OPTS: u8 = 0;
    pub const TCP: u8 = 6;
    pub const UDP: u8 = 17;
    pub const IP6: u8 = 41;
    pub const ROUTING: u8 = 43;
    pub const FRAGMENT: u8 = 44;
    pub const ICMP: u8 = 58;
    pub const NO_NEXT: u8 = 59;
    pub const DST_OPTS: u8 = 60;
    pub const MOBILITY: u8 = 135;
}

#[derive(Copy, Clone, Debug)]
pub struct IPAddr(pub [u8; 16]);

impl IPAddr {
    pub fn new() -> IPAddr {
        // Defaults to the unspecified address
        IPAddr([0; 16])
    }

    pub fn is_unspecified(&self) -> bool {
        self.0.iter().all(|&b| b == 0)
    }

    pub fn is_unicast_link_local(&self) -> bool {
        self.0[0] == 0xfe && (self.0[1] & 0xc0) == 0x80 && (self.0[1] & 0x3f) == 0
            && self.0[2..8].iter().all(|&b| b == 0)
    }

    pub fn set_unicast_link_local(&mut self) {
        self.0[0] = 0xfe;
        self.0[1] = 0x80;
        for i in 2..8 {
            self.0[i] = 0;
        }
    }

    // Panics if prefix slice does not contain enough bits
    pub fn set_prefix(&mut self, prefix: &[u8], prefix_len: u8) {
        let full_bytes = (prefix_len / 8) as usize;
        let remaining = (prefix_len & 0x7) as usize;
        let bytes = full_bytes + (if remaining != 0 { 1 } else { 0 });
        assert!(bytes <= prefix.len() && bytes <= 16);

        self.0[0..full_bytes].copy_from_slice(&prefix[0..full_bytes]);
        if remaining != 0 {
            let mask = (0xff as u8) << (8 - remaining);
            self.0[full_bytes] &= !mask;
            self.0[full_bytes] |= mask & prefix[full_bytes];
        }
    }

    pub fn is_multicast(&self) -> bool {
        self.0[0] == 0xff
    }
}

#[repr(C)]
#[derive(Copy, Clone)]
pub struct IP6Header {
    pub version_class_flow: [u8; 4],
    pub payload_len: u16,
    pub next_header: u8,
    pub hop_limit: u8,
    pub src_addr: IPAddr,
    pub dst_addr: IPAddr,
}

impl Default for IP6Header {
    fn default() -> IP6Header {
        let version = 0x60;
        let hop_limit = 255;
        IP6Header {
            version_class_flow: [version, 0, 0, 0],
            payload_len: 0,
            next_header: ip6_nh::NO_NEXT,
            hop_limit: hop_limit,
            src_addr: IPAddr::new(),
            dst_addr: IPAddr::new(),
        }
    }
}

impl IP6Header {
    pub fn new() -> IP6Header {
        IP6Header::default()
    }

    pub fn decode(buf: &[u8]) -> SResult<IP6Header> {
        // TODO: Let size of header be a constant
        stream_len_cond!(buf, 40);

        let mut ip6_header = Self::new();
        // Note that `dec_consume!` uses the length of the output buffer to
        // determine how many bytes are to be read.
        let off = dec_consume!(buf, 0; decode_bytes, &mut ip6_header.version_class_flow);
        let (off, payload_len_be) = dec_try!(buf, off; decode_u16);
        ip6_header.payload_len = u16::from_be(payload_len_be);
        let (off, next_header) = dec_try!(buf, off; decode_u8);
        ip6_header.next_header = next_header;
        let (off, hop_limit) = dec_try!(buf, off; decode_u8);
        ip6_header.hop_limit = hop_limit;
        let off = dec_consume!(buf, off; decode_bytes, &mut ip6_header.src_addr.0);
        let off = dec_consume!(buf, off; decode_bytes, &mut ip6_header.dst_addr.0);
        stream_done!(off, ip6_header);
    }

    // Returns the offset wrapped in an SResult
    pub fn encode(buf: &mut [u8], ip6_header: IP6Header) -> SResult<usize> {
        stream_len_cond!(buf, 40);

        let mut off = enc_consume!(buf, 0; encode_bytes, &ip6_header.version_class_flow);
        off = enc_consume!(buf, off; encode_u16, ip6_header.payload_len.to_be());
        off = enc_consume!(buf, off; encode_u8, ip6_header.next_header);
        off = enc_consume!(buf, off; encode_u8, ip6_header.hop_limit);
        off = enc_consume!(buf, off; encode_bytes, &ip6_header.src_addr.0);
        off = enc_consume!(buf, off; encode_bytes, &ip6_header.dst_addr.0);
        stream_done!(off, off);
    }

    // Version should always be 6
    pub fn get_version(&self) -> u8 {
        (self.version_class_flow[0] & 0xf0) >> 4
    }

    // TODO: Confirm order
    pub fn get_traffic_class(&self) -> u8 {
        (self.version_class_flow[0] & 0x0f) << 4 | (self.version_class_flow[1] & 0xf0) >> 4
    }

    pub fn set_traffic_class(&mut self, new_tc: u8) {
        self.version_class_flow[0] &= 0xf0;
        self.version_class_flow[0] |= (new_tc & 0xf0) >> 4;
        self.version_class_flow[1] &= 0x0f;
        self.version_class_flow[1] |= (new_tc & 0x0f) << 4;
    }

    fn get_dscp_unshifted(&self) -> u8 {
        self.get_traffic_class() & 0b11111100
    }

    pub fn get_dscp(&self) -> u8 {
        self.get_dscp_unshifted() >> 2
    }

    pub fn set_dscp(&mut self, new_dscp: u8) {
        let ecn = self.get_ecn();
        self.set_traffic_class(ecn | ((new_dscp << 2) & 0b11111100));
    }

    pub fn get_ecn(&self) -> u8 {
        self.get_traffic_class() & 0b11
    }

    pub fn set_ecn(&mut self, new_ecn: u8) {
        let dscp_unshifted = self.get_dscp_unshifted();
        self.set_traffic_class(dscp_unshifted | (new_ecn & 0b11));
    }

    // This returns the flow label as the lower 20 bits of a u32
    pub fn get_flow_label(&self) -> u32 {
        let mut flow_label: u32 = 0;
        flow_label |= ((self.version_class_flow[1] & 0x0f) as u32) << 16;
        flow_label |= (self.version_class_flow[2] as u32) << 8;
        flow_label |= self.version_class_flow[3] as u32;
        flow_label
    }

    pub fn set_flow_label(&mut self, new_fl_val: u32) {
        self.version_class_flow[1] &= 0xf0;
        self.version_class_flow[1] |= ((new_fl_val >> 16) & 0x0f) as u8;
        self.version_class_flow[2] = (new_fl_val >> 8) as u8;
        self.version_class_flow[3] = new_fl_val as u8;
    }

    // TODO: Is this in network byte order?
    pub fn get_payload_len(&self) -> u16 {
        u16::from_be(self.payload_len)
    }

    // TODO: 40 = size of IP6header - find idiomatic way to compute
    pub fn get_total_len(&self) -> u16 {
        40 + self.get_payload_len()
    }

    // TODO: Is this in network byte order?
    pub fn set_payload_len(&mut self, new_len: u16) {
        self.payload_len = new_len.to_be();
    }

    pub fn get_next_header(&self) -> u8 {
        self.next_header
    }

    pub fn set_next_header(&mut self, new_nh: u8) {
        self.next_header = new_nh;
    }

    pub fn get_hop_limit(&self) -> u8 {
        self.hop_limit
    }

    pub fn set_hop_limit(&mut self, new_hl: u8) {
        self.hop_limit = new_hl;
    }
}