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
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
use std::fmt;

use serde::{Serialize, Deserialize};
use crate::request::{Request, FromRequest, Outcome};

use crate::data::ByteUnit;
use crate::http::uncased::Uncased;

/// Mapping from (hierarchical) data types to size limits.
///
/// A `Limits` structure contains a mapping from a given hierarchical data type
/// ("form", "data-form", "ext/pdf", and so on) to the maximum size in bytes
/// that should be accepted by Rocket for said data type. For instance, if the
/// limit for "form" is set to `256`, only 256 bytes from an incoming non-data
/// form (that is, url-encoded) will be accepted.
///
/// To help in preventing DoS attacks, all incoming data reads must capped by a
/// limit. As such, all data guards impose a limit. The _name_ of the limit is
/// dictated by the data guard or type itself. For instance, [`Form`] imposes
/// the `form` limit for value-based forms and `data-form` limit for data-based
/// forms.
///
/// If a limit is exceeded, a guard will typically fail. The [`Capped`] type
/// allows retrieving some data types even when the limit is exceeded.
///
/// [`Capped`]: crate::data::Capped
/// [`Form`]: crate::form::Form
///
/// # Hierarchy
///
/// Data limits are hierarchical. The `/` (forward slash) character delimits the
/// levels, or layers, of a given limit. To obtain a limit value for a given
/// name, layers are peeled from right to left until a match is found, if any.
/// For example, fetching the limit named `pet/dog/bingo` will return the first
/// of `pet/dog/bingo`, `pet/dog` or `pet`:
///
/// ```rust
/// use rocket::data::{Limits, ToByteUnit};
///
/// let limits = Limits::default()
///     .limit("pet", 64.kibibytes())
///     .limit("pet/dog", 128.kibibytes())
///     .limit("pet/dog/bingo", 96.kibibytes());
///
/// assert_eq!(limits.get("pet/dog/bingo"), Some(96.kibibytes()));
/// assert_eq!(limits.get("pet/dog/ralph"), Some(128.kibibytes()));
/// assert_eq!(limits.get("pet/cat/bingo"), Some(64.kibibytes()));
///
/// assert_eq!(limits.get("pet/dog/bingo/hat"), Some(96.kibibytes()));
/// ```
///
/// # Built-in Limits
///
/// The following table details recognized built-in limits used by Rocket.
///
/// | Limit Name        | Default | Type         | Description                           |
/// |-------------------|---------|--------------|---------------------------------------|
/// | `form`            | 32KiB   | [`Form`]     | entire non-data-based form            |
/// | `data-form`       | 2MiB    | [`Form`]     | entire data-based form                |
/// | `file`            | 1MiB    | [`TempFile`] | [`TempFile`] data guard or form field |
/// | `file/$ext`       | _N/A_   | [`TempFile`] | file form field with extension `$ext` |
/// | `string`          | 8KiB    | [`String`]   | data guard or form field              |
/// | `string`          | 8KiB    | [`&str`]     | data guard or form field              |
/// | `bytes`           | 8KiB    | [`Vec<u8>`]  | data guard                            |
/// | `bytes`           | 8KiB    | [`&[u8]`]    | data guard or form field              |
/// | `json`            | 1MiB    | [`Json`]     | JSON data and form payloads           |
/// | `msgpack`         | 1MiB    | [`MsgPack`]  | MessagePack data and form payloads    |
///
/// [`TempFile`]: crate::fs::TempFile
/// [`Json`]: crate::serde::json::Json
/// [`MsgPack`]: crate::serde::msgpack::MsgPack
///
/// # Usage
///
/// A `Limits` structure is created following the builder pattern:
///
/// ```rust
/// use rocket::data::{Limits, ToByteUnit};
///
/// // Set a limit of 64KiB for forms, 3MiB for PDFs, and 1MiB for JSON.
/// let limits = Limits::default()
///     .limit("form", 64.kibibytes())
///     .limit("file/pdf", 3.mebibytes())
///     .limit("json", 2.mebibytes());
/// ```
///
/// The [`Limits::default()`](#impl-Default) method populates the `Limits`
/// structure with default limits in the [table above](#built-in-limits). A
/// configured limit can be retrieved via the `&Limits` request guard:
///
/// ```rust
/// # #[macro_use] extern crate rocket;
/// use std::io;
///
/// use rocket::data::{Data, Limits, ToByteUnit};
///
/// #[post("/echo", data = "<data>")]
/// async fn echo(data: Data<'_>, limits: &Limits) -> io::Result<String> {
///     let limit = limits.get("data").unwrap_or(1.mebibytes());
///     Ok(data.open(limit).into_string().await?.value)
/// }
/// ```
///
/// ...or via the [`Request::limits()`] method:
///
/// ```
/// # #[macro_use] extern crate rocket;
/// use rocket::request::Request;
/// use rocket::data::{self, Data, FromData};
///
/// # struct MyType;
/// # type MyError = ();
/// #[rocket::async_trait]
/// impl<'r> FromData<'r> for MyType {
///     type Error = MyError;
///
///     async fn from_data(req: &'r Request<'_>, data: Data<'r>) -> data::Outcome<'r, Self> {
///         let limit = req.limits().get("my-data-type");
///         /* .. */
///         # unimplemented!()
///     }
/// }
/// ```
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
#[serde(transparent)]
pub struct Limits {
    #[serde(deserialize_with = "Limits::deserialize")]
    #[serde(serialize_with = "figment::util::vec_tuple_map::serialize")]
    limits: Vec<(Uncased<'static>, ByteUnit)>,
}

impl Default for Limits {
    fn default() -> Limits {
        Limits::new()
            .limit("form", Limits::FORM)
            .limit("data-form", Limits::DATA_FORM)
            .limit("file", Limits::FILE)
            .limit("string", Limits::STRING)
            .limit("bytes", Limits::BYTES)
            .limit("json", Limits::JSON)
            .limit("msgpack", Limits::MESSAGE_PACK)
    }
}

impl Limits {
    /// Default limit for value-based forms.
    pub const FORM: ByteUnit = ByteUnit::Kibibyte(32);

    /// Default limit for data-based forms.
    pub const DATA_FORM: ByteUnit = ByteUnit::Mebibyte(2);

    /// Default limit for temporary files.
    pub const FILE: ByteUnit = ByteUnit::Mebibyte(1);

    /// Default limit for strings.
    pub const STRING: ByteUnit = ByteUnit::Kibibyte(8);

    /// Default limit for bytes.
    pub const BYTES: ByteUnit = ByteUnit::Kibibyte(8);

    /// Default limit for JSON payloads.
    pub const JSON: ByteUnit = ByteUnit::Mebibyte(1);

    /// Default limit for MessagePack payloads.
    pub const MESSAGE_PACK: ByteUnit = ByteUnit::Mebibyte(1);

    /// Construct a new `Limits` structure with no limits set.
    ///
    /// # Example
    ///
    /// ```rust
    /// use rocket::data::{Limits, ToByteUnit};
    ///
    /// let limits = Limits::default();
    /// assert_eq!(limits.get("form"), Some(32.kibibytes()));
    ///
    /// let limits = Limits::new();
    /// assert_eq!(limits.get("form"), None);
    /// ```
    #[inline]
    pub fn new() -> Self {
        Limits { limits: vec![] }
    }

    /// Adds or replaces a limit in `self`, consuming `self` and returning a new
    /// `Limits` structure with the added or replaced limit.
    ///
    /// # Example
    ///
    /// ```rust
    /// use rocket::data::{Limits, ToByteUnit};
    ///
    /// let limits = Limits::default();
    /// assert_eq!(limits.get("form"), Some(32.kibibytes()));
    /// assert_eq!(limits.get("json"), Some(1.mebibytes()));
    /// assert_eq!(limits.get("cat"), None);
    ///
    /// let limits = limits.limit("cat", 1.mebibytes());
    /// assert_eq!(limits.get("form"), Some(32.kibibytes()));
    /// assert_eq!(limits.get("cat"), Some(1.mebibytes()));
    ///
    /// let limits = limits.limit("json", 64.mebibytes());
    /// assert_eq!(limits.get("json"), Some(64.mebibytes()));
    /// ```
    pub fn limit<S: Into<Uncased<'static>>>(mut self, name: S, limit: ByteUnit) -> Self {
        let name = name.into();
        match self.limits.binary_search_by(|(k, _)| k.cmp(&name)) {
            Ok(i) => self.limits[i].1 = limit,
            Err(i) => self.limits.insert(i, (name, limit))
        }

        self
    }

    /// Returns the limit named `name`, proceeding hierarchically from right
    /// to left until one is found, or returning `None` if none is found.
    ///
    /// # Example
    ///
    /// ```rust
    /// use rocket::data::{Limits, ToByteUnit};
    ///
    /// let limits = Limits::default()
    ///     .limit("json", 2.mebibytes())
    ///     .limit("file/jpeg", 4.mebibytes())
    ///     .limit("file/jpeg/special", 8.mebibytes());
    ///
    /// assert_eq!(limits.get("form"), Some(32.kibibytes()));
    /// assert_eq!(limits.get("json"), Some(2.mebibytes()));
    /// assert_eq!(limits.get("data-form"), Some(Limits::DATA_FORM));
    ///
    /// assert_eq!(limits.get("file"), Some(1.mebibytes()));
    /// assert_eq!(limits.get("file/png"), Some(1.mebibytes()));
    /// assert_eq!(limits.get("file/jpeg"), Some(4.mebibytes()));
    /// assert_eq!(limits.get("file/jpeg/inner"), Some(4.mebibytes()));
    /// assert_eq!(limits.get("file/jpeg/special"), Some(8.mebibytes()));
    ///
    /// assert!(limits.get("cats").is_none());
    /// ```
    pub fn get<S: AsRef<str>>(&self, name: S) -> Option<ByteUnit> {
        let mut name = name.as_ref();
        let mut indices = name.rmatch_indices('/');
        loop {
            let exact_limit = self.limits
                .binary_search_by(|(k, _)| k.as_uncased_str().cmp(name.into()))
                .map(|i| self.limits[i].1);

            if let Ok(exact) = exact_limit {
                return Some(exact);
            }

            let (i, _) = indices.next()?;
            name = &name[..i];
        }
    }

    /// Returns the limit for the name created by joining the strings in
    /// `layers` with `/` as a separator, then proceeding like
    /// [`Limits::get()`], hierarchically from right to left until one is found,
    /// or returning `None` if none is found.
    ///
    /// This methods exists to allow finding hierarchical limits without
    /// constructing a string to call `get()` with but otherwise returns the
    /// same results.
    ///
    /// # Example
    ///
    /// ```rust
    /// use rocket::data::{Limits, ToByteUnit};
    ///
    /// let limits = Limits::default()
    ///     .limit("json", 2.mebibytes())
    ///     .limit("file/jpeg", 4.mebibytes())
    ///     .limit("file/jpeg/special", 8.mebibytes());
    ///
    /// assert_eq!(limits.find(["json"]), Some(2.mebibytes()));
    /// assert_eq!(limits.find(["json", "person"]), Some(2.mebibytes()));
    ///
    /// assert_eq!(limits.find(["file"]), Some(1.mebibytes()));
    /// assert_eq!(limits.find(["file", "png"]), Some(1.mebibytes()));
    /// assert_eq!(limits.find(["file", "jpeg"]), Some(4.mebibytes()));
    /// assert_eq!(limits.find(["file", "jpeg", "inner"]), Some(4.mebibytes()));
    /// assert_eq!(limits.find(["file", "jpeg", "special"]), Some(8.mebibytes()));
    ///
    /// # let s: &[&str] = &[]; assert_eq!(limits.find(s), None);
    /// ```
    pub fn find<S: AsRef<str>, L: AsRef<[S]>>(&self, layers: L) -> Option<ByteUnit> {
        let layers = layers.as_ref();
        for j in (1..=layers.len()).rev() {
            let layers = &layers[..j];
            let opt = self.limits
                .binary_search_by(|(k, _)| {
                    let k_layers = k.as_str().split('/');
                    k_layers.cmp(layers.iter().map(|s| s.as_ref()))
                })
                .map(|i| self.limits[i].1);

            if let Ok(byte_unit) = opt {
                return Some(byte_unit);
            }
        }

        None
    }

    /// Deserialize a `Limits` vector from a map. Ensures that the resulting
    /// vector is properly sorted for futures lookups via binary search.
    fn deserialize<'de, D>(de: D) -> Result<Vec<(Uncased<'static>, ByteUnit)>, D::Error>
        where D: serde::Deserializer<'de>
    {
        let mut limits = figment::util::vec_tuple_map::deserialize(de)?;
        limits.sort();
        Ok(limits)
    }
}

impl fmt::Display for Limits {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        for (i, (k, v)) in self.limits.iter().enumerate() {
            if i != 0 { f.write_str(", ")? }
            write!(f, "{} = {}", k, v)?;
        }

        Ok(())
    }
}

#[crate::async_trait]
impl<'r> FromRequest<'r> for &'r Limits {
    type Error = std::convert::Infallible;

    async fn from_request(req: &'r Request<'_>) -> Outcome<Self, Self::Error> {
        Outcome::Success(req.limits())
    }
}