1use crate::frame::{Error, Frame, Head, Kind, StreamId};
2use bytes::BufMut;
3
4const ACK_FLAG: u8 = 0x1;
5
6pub type Payload = [u8; 8];
7
8#[derive(Debug, Eq, PartialEq)]
9pub 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.
16const SHUTDOWN_PAYLOAD: Payload = [0x0b, 0x7b, 0xa2, 0xf0, 0x8b, 0x9b, 0xfe, 0x54];
17const USER_PAYLOAD: Payload = [0x3b, 0x7c, 0xdb, 0x7a, 0x0b, 0x87, 0x16, 0xb4];
18
19impl 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
32 pub fn new(payload: Payload) -> Ping {
33 Ping {
34 ack: false,
35 payload,
36 }
37 }
38
39 pub fn pong(payload: Payload) -> Ping {
40 Ping { ack: true, payload }
41 }
42
43 pub fn is_ack(&self) -> bool {
44 self.ack
45 }
46
47 pub fn payload(&self) -> &Payload {
48 &self.payload
49 }
50
51 pub fn into_payload(self) -> Payload {
52 self.payload
53 }
54
55 /// Builds a `Ping` frame from a raw frame.
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
86 pub fn encode<B: BufMut>(&self, dst: &mut B) {
87 let sz = self.payload.len();
88 tracing::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
98impl<T> From<Ping> for Frame<T> {
99 fn from(src: Ping) -> Frame<T> {
100 Frame::Ping(src)
101 }
102}
103