1 use crate::frame::{Error, Frame, Head, Kind, StreamId};
2 use bytes::BufMut;
3 
4 const ACK_FLAG: u8 = 0x1;
5 
6 pub type Payload = [u8; 8];
7 
8 #[derive(Debug, Eq, PartialEq)]
9 pub struct Ping {
10     ack: bool,
11     payload: Payload,
12 }
13 
14 // This was just 8 randomly generated bytes. We use something besides just
15 // zeroes to distinguish this specific PING from any other.
16 const SHUTDOWN_PAYLOAD: Payload = [0x0b, 0x7b, 0xa2, 0xf0, 0x8b, 0x9b, 0xfe, 0x54];
17 const USER_PAYLOAD: Payload = [0x3b, 0x7c, 0xdb, 0x7a, 0x0b, 0x87, 0x16, 0xb4];
18 
19 impl Ping {
20     #[cfg(feature = "unstable")]
21     pub const SHUTDOWN: Payload = SHUTDOWN_PAYLOAD;
22 
23     #[cfg(not(feature = "unstable"))]
24     pub(crate) const SHUTDOWN: Payload = SHUTDOWN_PAYLOAD;
25 
26     #[cfg(feature = "unstable")]
27     pub const USER: Payload = USER_PAYLOAD;
28 
29     #[cfg(not(feature = "unstable"))]
30     pub(crate) const USER: Payload = USER_PAYLOAD;
31 
new(payload: Payload) -> Ping32     pub fn new(payload: Payload) -> Ping {
33         Ping {
34             ack: false,
35             payload,
36         }
37     }
38 
pong(payload: Payload) -> Ping39     pub fn pong(payload: Payload) -> Ping {
40         Ping { ack: true, payload }
41     }
42 
is_ack(&self) -> bool43     pub fn is_ack(&self) -> bool {
44         self.ack
45     }
46 
payload(&self) -> &Payload47     pub fn payload(&self) -> &Payload {
48         &self.payload
49     }
50 
into_payload(self) -> Payload51     pub fn into_payload(self) -> Payload {
52         self.payload
53     }
54 
55     /// Builds a `Ping` frame from a raw frame.
load(head: Head, bytes: &[u8]) -> Result<Ping, Error>56     pub fn load(head: Head, bytes: &[u8]) -> Result<Ping, Error> {
57         debug_assert_eq!(head.kind(), crate::frame::Kind::Ping);
58 
59         // PING frames are not associated with any individual stream. If a PING
60         // frame is received with a stream identifier field value other than
61         // 0x0, the recipient MUST respond with a connection error
62         // (Section 5.4.1) of type PROTOCOL_ERROR.
63         if !head.stream_id().is_zero() {
64             return Err(Error::InvalidStreamId);
65         }
66 
67         // In addition to the frame header, PING frames MUST contain 8 octets of opaque
68         // data in the payload.
69         if bytes.len() != 8 {
70             return Err(Error::BadFrameSize);
71         }
72 
73         let mut payload = [0; 8];
74         payload.copy_from_slice(bytes);
75 
76         // The PING frame defines the following flags:
77         //
78         // ACK (0x1): When set, bit 0 indicates that this PING frame is a PING
79         //    response. An endpoint MUST set this flag in PING responses. An
80         //    endpoint MUST NOT respond to PING frames containing this flag.
81         let ack = head.flag() & ACK_FLAG != 0;
82 
83         Ok(Ping { ack, payload })
84     }
85 
encode<B: BufMut>(&self, dst: &mut B)86     pub fn encode<B: BufMut>(&self, dst: &mut B) {
87         let sz = self.payload.len();
88         log::trace!("encoding PING; ack={} len={}", self.ack, sz);
89 
90         let flags = if self.ack { ACK_FLAG } else { 0 };
91         let head = Head::new(Kind::Ping, flags, StreamId::zero());
92 
93         head.encode(sz, dst);
94         dst.put_slice(&self.payload);
95     }
96 }
97 
98 impl<T> From<Ping> for Frame<T> {
from(src: Ping) -> Frame<T>99     fn from(src: Ping) -> Frame<T> {
100         Frame::Ping(src)
101     }
102 }
103