h2/frame/
settings.rs

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1use std::fmt;
2
3use crate::frame::{util, Error, Frame, FrameSize, Head, Kind, StreamId};
4use bytes::{BufMut, BytesMut};
5
6#[derive(Clone, Default, Eq, PartialEq)]
7pub struct Settings {
8    flags: SettingsFlags,
9    // Fields
10    header_table_size: Option<u32>,
11    enable_push: Option<u32>,
12    max_concurrent_streams: Option<u32>,
13    initial_window_size: Option<u32>,
14    max_frame_size: Option<u32>,
15    max_header_list_size: Option<u32>,
16    enable_connect_protocol: Option<u32>,
17}
18
19/// An enum that lists all valid settings that can be sent in a SETTINGS
20/// frame.
21///
22/// Each setting has a value that is a 32 bit unsigned integer (6.5.1.).
23#[derive(Debug)]
24pub enum Setting {
25    HeaderTableSize(u32),
26    EnablePush(u32),
27    MaxConcurrentStreams(u32),
28    InitialWindowSize(u32),
29    MaxFrameSize(u32),
30    MaxHeaderListSize(u32),
31    EnableConnectProtocol(u32),
32}
33
34#[derive(Copy, Clone, Eq, PartialEq, Default)]
35pub struct SettingsFlags(u8);
36
37const ACK: u8 = 0x1;
38const ALL: u8 = ACK;
39
40/// The default value of SETTINGS_HEADER_TABLE_SIZE
41pub const DEFAULT_SETTINGS_HEADER_TABLE_SIZE: usize = 4_096;
42
43/// The default value of SETTINGS_INITIAL_WINDOW_SIZE
44pub const DEFAULT_INITIAL_WINDOW_SIZE: u32 = 65_535;
45
46/// The default value of MAX_FRAME_SIZE
47pub const DEFAULT_MAX_FRAME_SIZE: FrameSize = 16_384;
48
49/// INITIAL_WINDOW_SIZE upper bound
50pub const MAX_INITIAL_WINDOW_SIZE: usize = (1 << 31) - 1;
51
52/// MAX_FRAME_SIZE upper bound
53pub const MAX_MAX_FRAME_SIZE: FrameSize = (1 << 24) - 1;
54
55// ===== impl Settings =====
56
57impl Settings {
58    pub fn ack() -> Settings {
59        Settings {
60            flags: SettingsFlags::ack(),
61            ..Settings::default()
62        }
63    }
64
65    pub fn is_ack(&self) -> bool {
66        self.flags.is_ack()
67    }
68
69    pub fn initial_window_size(&self) -> Option<u32> {
70        self.initial_window_size
71    }
72
73    pub fn set_initial_window_size(&mut self, size: Option<u32>) {
74        self.initial_window_size = size;
75    }
76
77    pub fn max_concurrent_streams(&self) -> Option<u32> {
78        self.max_concurrent_streams
79    }
80
81    pub fn set_max_concurrent_streams(&mut self, max: Option<u32>) {
82        self.max_concurrent_streams = max;
83    }
84
85    pub fn max_frame_size(&self) -> Option<u32> {
86        self.max_frame_size
87    }
88
89    pub fn set_max_frame_size(&mut self, size: Option<u32>) {
90        if let Some(val) = size {
91            assert!(DEFAULT_MAX_FRAME_SIZE <= val && val <= MAX_MAX_FRAME_SIZE);
92        }
93        self.max_frame_size = size;
94    }
95
96    pub fn max_header_list_size(&self) -> Option<u32> {
97        self.max_header_list_size
98    }
99
100    pub fn set_max_header_list_size(&mut self, size: Option<u32>) {
101        self.max_header_list_size = size;
102    }
103
104    pub fn is_push_enabled(&self) -> Option<bool> {
105        self.enable_push.map(|val| val != 0)
106    }
107
108    pub fn set_enable_push(&mut self, enable: bool) {
109        self.enable_push = Some(enable as u32);
110    }
111
112    pub fn is_extended_connect_protocol_enabled(&self) -> Option<bool> {
113        self.enable_connect_protocol.map(|val| val != 0)
114    }
115
116    pub fn set_enable_connect_protocol(&mut self, val: Option<u32>) {
117        self.enable_connect_protocol = val;
118    }
119
120    pub fn header_table_size(&self) -> Option<u32> {
121        self.header_table_size
122    }
123
124    pub fn set_header_table_size(&mut self, size: Option<u32>) {
125        self.header_table_size = size;
126    }
127
128    pub fn load(head: Head, payload: &[u8]) -> Result<Settings, Error> {
129        use self::Setting::*;
130
131        debug_assert_eq!(head.kind(), crate::frame::Kind::Settings);
132
133        if !head.stream_id().is_zero() {
134            return Err(Error::InvalidStreamId);
135        }
136
137        // Load the flag
138        let flag = SettingsFlags::load(head.flag());
139
140        if flag.is_ack() {
141            // Ensure that the payload is empty
142            if !payload.is_empty() {
143                return Err(Error::InvalidPayloadLength);
144            }
145
146            // Return the ACK frame
147            return Ok(Settings::ack());
148        }
149
150        // Ensure the payload length is correct, each setting is 6 bytes long.
151        if payload.len() % 6 != 0 {
152            tracing::debug!("invalid settings payload length; len={:?}", payload.len());
153            return Err(Error::InvalidPayloadAckSettings);
154        }
155
156        let mut settings = Settings::default();
157        debug_assert!(!settings.flags.is_ack());
158
159        for raw in payload.chunks(6) {
160            match Setting::load(raw) {
161                Some(HeaderTableSize(val)) => {
162                    settings.header_table_size = Some(val);
163                }
164                Some(EnablePush(val)) => match val {
165                    0 | 1 => {
166                        settings.enable_push = Some(val);
167                    }
168                    _ => {
169                        return Err(Error::InvalidSettingValue);
170                    }
171                },
172                Some(MaxConcurrentStreams(val)) => {
173                    settings.max_concurrent_streams = Some(val);
174                }
175                Some(InitialWindowSize(val)) => {
176                    if val as usize > MAX_INITIAL_WINDOW_SIZE {
177                        return Err(Error::InvalidSettingValue);
178                    } else {
179                        settings.initial_window_size = Some(val);
180                    }
181                }
182                Some(MaxFrameSize(val)) => {
183                    if DEFAULT_MAX_FRAME_SIZE <= val && val <= MAX_MAX_FRAME_SIZE {
184                        settings.max_frame_size = Some(val);
185                    } else {
186                        return Err(Error::InvalidSettingValue);
187                    }
188                }
189                Some(MaxHeaderListSize(val)) => {
190                    settings.max_header_list_size = Some(val);
191                }
192                Some(EnableConnectProtocol(val)) => match val {
193                    0 | 1 => {
194                        settings.enable_connect_protocol = Some(val);
195                    }
196                    _ => {
197                        return Err(Error::InvalidSettingValue);
198                    }
199                },
200                None => {}
201            }
202        }
203
204        Ok(settings)
205    }
206
207    fn payload_len(&self) -> usize {
208        let mut len = 0;
209        self.for_each(|_| len += 6);
210        len
211    }
212
213    pub fn encode(&self, dst: &mut BytesMut) {
214        // Create & encode an appropriate frame head
215        let head = Head::new(Kind::Settings, self.flags.into(), StreamId::zero());
216        let payload_len = self.payload_len();
217
218        tracing::trace!("encoding SETTINGS; len={}", payload_len);
219
220        head.encode(payload_len, dst);
221
222        // Encode the settings
223        self.for_each(|setting| {
224            tracing::trace!("encoding setting; val={:?}", setting);
225            setting.encode(dst)
226        });
227    }
228
229    fn for_each<F: FnMut(Setting)>(&self, mut f: F) {
230        use self::Setting::*;
231
232        if let Some(v) = self.header_table_size {
233            f(HeaderTableSize(v));
234        }
235
236        if let Some(v) = self.enable_push {
237            f(EnablePush(v));
238        }
239
240        if let Some(v) = self.max_concurrent_streams {
241            f(MaxConcurrentStreams(v));
242        }
243
244        if let Some(v) = self.initial_window_size {
245            f(InitialWindowSize(v));
246        }
247
248        if let Some(v) = self.max_frame_size {
249            f(MaxFrameSize(v));
250        }
251
252        if let Some(v) = self.max_header_list_size {
253            f(MaxHeaderListSize(v));
254        }
255
256        if let Some(v) = self.enable_connect_protocol {
257            f(EnableConnectProtocol(v));
258        }
259    }
260}
261
262impl<T> From<Settings> for Frame<T> {
263    fn from(src: Settings) -> Frame<T> {
264        Frame::Settings(src)
265    }
266}
267
268impl fmt::Debug for Settings {
269    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
270        let mut builder = f.debug_struct("Settings");
271        builder.field("flags", &self.flags);
272
273        self.for_each(|setting| match setting {
274            Setting::EnablePush(v) => {
275                builder.field("enable_push", &v);
276            }
277            Setting::HeaderTableSize(v) => {
278                builder.field("header_table_size", &v);
279            }
280            Setting::InitialWindowSize(v) => {
281                builder.field("initial_window_size", &v);
282            }
283            Setting::MaxConcurrentStreams(v) => {
284                builder.field("max_concurrent_streams", &v);
285            }
286            Setting::MaxFrameSize(v) => {
287                builder.field("max_frame_size", &v);
288            }
289            Setting::MaxHeaderListSize(v) => {
290                builder.field("max_header_list_size", &v);
291            }
292            Setting::EnableConnectProtocol(v) => {
293                builder.field("enable_connect_protocol", &v);
294            }
295        });
296
297        builder.finish()
298    }
299}
300
301// ===== impl Setting =====
302
303impl Setting {
304    /// Creates a new `Setting` with the correct variant corresponding to the
305    /// given setting id, based on the settings IDs defined in section
306    /// 6.5.2.
307    pub fn from_id(id: u16, val: u32) -> Option<Setting> {
308        use self::Setting::*;
309
310        match id {
311            1 => Some(HeaderTableSize(val)),
312            2 => Some(EnablePush(val)),
313            3 => Some(MaxConcurrentStreams(val)),
314            4 => Some(InitialWindowSize(val)),
315            5 => Some(MaxFrameSize(val)),
316            6 => Some(MaxHeaderListSize(val)),
317            8 => Some(EnableConnectProtocol(val)),
318            _ => None,
319        }
320    }
321
322    /// Creates a new `Setting` by parsing the given buffer of 6 bytes, which
323    /// contains the raw byte representation of the setting, according to the
324    /// "SETTINGS format" defined in section 6.5.1.
325    ///
326    /// The `raw` parameter should have length at least 6 bytes, since the
327    /// length of the raw setting is exactly 6 bytes.
328    ///
329    /// # Panics
330    ///
331    /// If given a buffer shorter than 6 bytes, the function will panic.
332    fn load(raw: &[u8]) -> Option<Setting> {
333        let id: u16 = (u16::from(raw[0]) << 8) | u16::from(raw[1]);
334        let val: u32 = unpack_octets_4!(raw, 2, u32);
335
336        Setting::from_id(id, val)
337    }
338
339    fn encode(&self, dst: &mut BytesMut) {
340        use self::Setting::*;
341
342        let (kind, val) = match *self {
343            HeaderTableSize(v) => (1, v),
344            EnablePush(v) => (2, v),
345            MaxConcurrentStreams(v) => (3, v),
346            InitialWindowSize(v) => (4, v),
347            MaxFrameSize(v) => (5, v),
348            MaxHeaderListSize(v) => (6, v),
349            EnableConnectProtocol(v) => (8, v),
350        };
351
352        dst.put_u16(kind);
353        dst.put_u32(val);
354    }
355}
356
357// ===== impl SettingsFlags =====
358
359impl SettingsFlags {
360    pub fn empty() -> SettingsFlags {
361        SettingsFlags(0)
362    }
363
364    pub fn load(bits: u8) -> SettingsFlags {
365        SettingsFlags(bits & ALL)
366    }
367
368    pub fn ack() -> SettingsFlags {
369        SettingsFlags(ACK)
370    }
371
372    pub fn is_ack(&self) -> bool {
373        self.0 & ACK == ACK
374    }
375}
376
377impl From<SettingsFlags> for u8 {
378    fn from(src: SettingsFlags) -> u8 {
379        src.0
380    }
381}
382
383impl fmt::Debug for SettingsFlags {
384    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
385        util::debug_flags(f, self.0)
386            .flag_if(self.is_ack(), "ACK")
387            .finish()
388    }
389}
h2/frame/settings.rs

h2/frame/
settings.rs
