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
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
use crate::http::{RawStr, Status};
use crate::request::{Request, local_cache};
use crate::data::{Data, Limits};
use crate::outcome::{self, IntoOutcome, try_outcome, Outcome::*};

/// Type alias for the `Outcome` of [`FromData`].
///
/// [`FromData`]: crate::data::FromData
pub type Outcome<'r, T, E = <T as FromData<'r>>::Error>
    = outcome::Outcome<T, (Status, E), (Data<'r>, Status)>;

impl<'r, S, E> IntoOutcome<S, (Status, E), (Data<'r>, Status)> for Result<S, E> {
    type Failure = Status;
    type Forward = (Data<'r>, Status);

    #[inline]
    fn into_outcome(self, status: Status) -> Outcome<'r, S, E> {
        match self {
            Ok(val) => Success(val),
            Err(err) => Failure((status, err))
        }
    }

    #[inline]
    fn or_forward(self, (data, status): (Data<'r>, Status)) -> Outcome<'r, S, E> {
        match self {
            Ok(val) => Success(val),
            Err(_) => Forward((data, status))
        }
    }
}

/// Trait implemented by data guards to derive a value from request body data.
///
/// # Data Guards
///
/// A data guard is a guard that operates on a request's body data. Data guards
/// validate and parse request body data via implementations of `FromData`. In
/// other words, a type is a data guard _iff_ it implements `FromData`.
///
/// Data guards are the target of the `data` route attribute parameter:
///
/// ```rust
/// # #[macro_use] extern crate rocket;
/// # type DataGuard = String;
/// #[post("/submit", data = "<var>")]
/// fn submit(var: DataGuard) { /* ... */ }
/// ```
///
/// A route can have at most one data guard. Above, `var` is used as the
/// argument name for the data guard type `DataGuard`. When the `submit` route
/// matches, Rocket will call the `FromData` implementation for the type `T`.
/// The handler will only be called if the guard returns successfully.
///
/// ## Build-In Guards
///
/// Rocket provides implementations for `FromData` for many types. Their
/// behavior is documented here:
///
///   * `Data`: Returns the untouched `Data`.
///
///     - **Fails:** Never.
///
///     - **Succeeds:** Always.
///
///     - **Forwards:** Never.
///
///   * Strings: `Cow<str>`, `&str`, `&RawStr`, `String`
///
///     _Limited by the `string` [data limit]._
///
///     Reads the body data into a string via [`DataStream::into_string()`].
///
///     - **Fails:** If the body data is not valid UTF-8 or on I/O errors while
///     reading. The error type is [`io::Error`].
///
///     - **Succeeds:** If the body data _is_ valid UTF-8. If the limit is
///     exceeded, the string is truncated to the limit.
///
///     - **Forwards:** Never.
///
///   * Bytes: `&[u8]`, `Vec<u8>`
///
///     _Limited by the `bytes` [data limit]._
///
///     Reads the body data into a byte vector via [`DataStream::into_bytes()`].
///
///     - **Fails:** On I/O errors while reading. The error type is
///     [`io::Error`].
///
///     - **Succeeds:** As long as no I/O error occurs. If the limit is
///     exceeded, the slice is truncated to the limit.
///
///     - **Forwards:** Never.
///
///   * [`TempFile`](crate::fs::TempFile)
///
///     _Limited by the `file` and/or `file/$ext` [data limit]._
///
///     Streams the body data directly into a temporary file. The data is never
///     buffered in memory.
///
///     - **Fails:** On I/O errors while reading data or creating the temporary
///     file. The error type is [`io::Error`].
///
///     - **Succeeds:** As long as no I/O error occurs and the temporary file
///     could be created. If the limit is exceeded, only data up to the limit is
///     read and subsequently written.
///
///     - **Forwards:** Never.
///
///   * Deserializers: [`Json<T>`], [`MsgPack<T>`]
///
///     _Limited by the `json`, `msgpack` [data limit], respectively._
///
///     Reads up to the configured limit and deserializes the read data into `T`
///     using the respective format's parser.
///
///     - **Fails:** On I/O errors while reading the data, or if the data fails
///     to parse as a `T` according to the deserializer. The error type for
///     `Json` is [`json::Error`](crate::serde::json::Error) and the error type
///     for `MsgPack` is [`msgpack::Error`](crate::serde::msgpack::Error).
///
///     - **Succeeds:** As long as no I/O error occurs and the (limited) body
///     data was successfully deserialized as a `T`.
///
///     - **Forwards:** Never.
///
///   * Forms: [`Form<T>`]
///
///     _Limited by the `form` or `data-form` [data limit]._
///
///     Parses the incoming data stream into fields according to Rocket's [field
///     wire format], pushes each field to `T`'s [`FromForm`] [push parser], and
///     finalizes the form. Parsing is done on the stream without reading the
///     data into memory. If the request has as a [`ContentType::Form`], the
///     `form` limit is applied, otherwise if the request has a
///     [`ContentType::FormData`], the `data-form` limit is applied.
///
///     - **Fails:** On I/O errors while reading the data, or if the data fails
///     to parse as a `T` according to its `FromForm` implementation. The errors
///     are collected into an [`Errors`](crate::form::Errors), the error type.
///
///     - **Succeeds:** As long as no I/O error occurs and the (limited) body
///     data was successfully parsed as a `T`.
///
///     - **Forwards:** If the request's `Content-Type` is neither
///     [`ContentType::Form`] nor [`ContentType::FormData`].
///
///   * `Option<T>`
///
///     Forwards to `T`'s `FromData` implementation, capturing the outcome.
///
///     - **Fails:** Never.
///
///     - **Succeeds:** Always. If `T`'s `FromData` implementation succeeds, the
///     parsed value is returned in `Some`. If its implementation forwards or
///     fails, `None` is returned.
///
///     - **Forwards:** Never.
///
///   * `Result<T, T::Error>`
///
///     Forwards to `T`'s `FromData` implementation, capturing the outcome.
///
///     - **Fails:** Never.
///
///     - **Succeeds:** If `T`'s `FromData` implementation succeeds or fails. If
///     it succeeds, the value is returned in `Ok`. If it fails, the error value
///     is returned in `Err`.
///
///     - **Forwards:** If `T`'s implementation forwards.
///
///   * [`Capped<T>`]
///
///     Forwards to `T`'s `FromData` implementation, recording whether the data
///     was truncated (a.k.a. capped) due to `T`'s limit being exceeded.
///
///     - **Fails:** If `T`'s implementation fails.
///     - **Succeeds:** If `T`'s implementation succeeds.
///     - **Forwards:** If `T`'s implementation forwards.
///
/// [data limit]: crate::data::Limits#built-in-limits
/// [`DataStream::into_string()`]: crate::data::DataStream::into_string()
/// [`DataStream::into_bytes()`]: crate::data::DataStream::into_bytes()
/// [`io::Error`]: std::io::Error
/// [`Json<T>`]: crate::serde::json::Json
/// [`MsgPack<T>`]: crate::serde::msgpack::MsgPack
/// [`Form<T>`]: crate::form::Form
/// [field wire format]: crate::form#field-wire-format
/// [`FromForm`]: crate::form::FromForm
/// [push parser]: crate::form::FromForm#push-parsing
/// [`ContentType::Form`]: crate::http::ContentType::Form
/// [`ContentType::FormData`]: crate::http::ContentType::FormData
///
/// ## Async Trait
///
/// [`FromData`] is an _async_ trait. Implementations of `FromData` must be
/// decorated with an attribute of `#[rocket::async_trait]`:
///
/// ```rust
/// use rocket::request::Request;
/// use rocket::data::{self, Data, FromData};
/// # struct MyType;
/// # type MyError = String;
///
/// #[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> {
///         /* .. */
///         # unimplemented!()
///     }
/// }
/// ```
///
/// # Example
///
/// Say that you have a custom type, `Person`:
///
/// ```rust
/// struct Person<'r> {
///     name: &'r str,
///     age: u16
/// }
/// ```
///
/// `Person` has a custom serialization format, so the built-in `Json` type
/// doesn't suffice. The format is `<name>:<age>` with `Content-Type:
/// application/x-person`. You'd like to use `Person` as a data guard, so that
/// you can retrieve it directly from a client's request body:
///
/// ```rust
/// # use rocket::post;
/// # type Person<'r> = &'r rocket::http::RawStr;
/// #[post("/person", data = "<person>")]
/// fn person(person: Person<'_>) -> &'static str {
///     "Saved the new person to the database!"
/// }
/// ```
///
/// A `FromData` implementation for such a type might look like:
///
/// ```rust
/// # #[macro_use] extern crate rocket;
/// #
/// # #[derive(Debug)]
/// # struct Person<'r> { name: &'r str, age: u16 }
/// #
/// use rocket::request::{self, Request};
/// use rocket::data::{self, Data, FromData, ToByteUnit};
/// use rocket::http::{Status, ContentType};
///
/// #[derive(Debug)]
/// enum Error {
///     TooLarge,
///     NoColon,
///     InvalidAge,
///     Io(std::io::Error),
/// }
///
/// #[rocket::async_trait]
/// impl<'r> FromData<'r> for Person<'r> {
///     type Error = Error;
///
///     async fn from_data(req: &'r Request<'_>, data: Data<'r>) -> data::Outcome<'r, Self> {
///         use Error::*;
///         use rocket::outcome::Outcome::*;
///
///         // Ensure the content type is correct before opening the data.
///         let person_ct = ContentType::new("application", "x-person");
///         if req.content_type() != Some(&person_ct) {
///             return Forward((data, Status::NotFound));
///         }
///
///         // Use a configured limit with name 'person' or fallback to default.
///         let limit = req.limits().get("person").unwrap_or(256.bytes());
///
///         // Read the data into a string.
///         let string = match data.open(limit).into_string().await {
///             Ok(string) if string.is_complete() => string.into_inner(),
///             Ok(_) => return Failure((Status::PayloadTooLarge, TooLarge)),
///             Err(e) => return Failure((Status::InternalServerError, Io(e))),
///         };
///
///         // We store `string` in request-local cache for long-lived borrows.
///         let string = request::local_cache!(req, string);
///
///         // Split the string into two pieces at ':'.
///         let (name, age) = match string.find(':') {
///             Some(i) => (&string[..i], &string[(i + 1)..]),
///             None => return Failure((Status::UnprocessableEntity, NoColon)),
///         };
///
///         // Parse the age.
///         let age: u16 = match age.parse() {
///             Ok(age) => age,
///             Err(_) => return Failure((Status::UnprocessableEntity, InvalidAge)),
///         };
///
///         Success(Person { name, age })
///     }
/// }
///
/// // The following routes now typecheck...
///
/// #[post("/person", data = "<person>")]
/// fn person(person: Person<'_>) { /* .. */ }
///
/// #[post("/person", data = "<person>")]
/// fn person2(person: Result<Person<'_>, Error>) { /* .. */ }
///
/// #[post("/person", data = "<person>")]
/// fn person3(person: Option<Person<'_>>) { /* .. */ }
///
/// #[post("/person", data = "<person>")]
/// fn person4(person: Person<'_>) -> &str {
///     // Note that this is only possible because the data in `person` live
///     // as long as the request through request-local cache.
///     person.name
/// }
/// ```
#[crate::async_trait]
pub trait FromData<'r>: Sized {
    /// The associated error to be returned when the guard fails.
    type Error: Send + std::fmt::Debug;

    /// Asynchronously validates, parses, and converts an instance of `Self`
    /// from the incoming request body data.
    ///
    /// If validation and parsing succeeds, an outcome of `Success` is returned.
    /// If the data is not appropriate given the type of `Self`, `Forward` is
    /// returned. If parsing fails, `Failure` is returned.
    async fn from_data(req: &'r Request<'_>, data: Data<'r>) -> Outcome<'r, Self>;
}

use crate::data::Capped;

#[crate::async_trait]
impl<'r> FromData<'r> for Capped<String> {
    type Error = std::io::Error;

    async fn from_data(req: &'r Request<'_>, data: Data<'r>) -> Outcome<'r, Self> {
        let limit = req.limits().get("string").unwrap_or(Limits::STRING);
        data.open(limit).into_string().await.into_outcome(Status::BadRequest)
    }
}

impl_strict_from_data_from_capped!(String);

#[crate::async_trait]
impl<'r> FromData<'r> for Capped<&'r str> {
    type Error = std::io::Error;

    async fn from_data(req: &'r Request<'_>, data: Data<'r>) -> Outcome<'r, Self> {
        let capped = try_outcome!(<Capped<String>>::from_data(req, data).await);
        let string = capped.map(|s| local_cache!(req, s));
        Success(string)
    }
}

impl_strict_from_data_from_capped!(&'r str);

#[crate::async_trait]
impl<'r> FromData<'r> for Capped<&'r RawStr> {
    type Error = std::io::Error;

    async fn from_data(req: &'r Request<'_>, data: Data<'r>) -> Outcome<'r, Self> {
        let capped = try_outcome!(<Capped<String>>::from_data(req, data).await);
        let raw = capped.map(|s| RawStr::new(local_cache!(req, s)));
        Success(raw)
    }
}

impl_strict_from_data_from_capped!(&'r RawStr);

#[crate::async_trait]
impl<'r> FromData<'r> for Capped<std::borrow::Cow<'_, str>> {
    type Error = std::io::Error;

    async fn from_data(req: &'r Request<'_>, data: Data<'r>) -> Outcome<'r, Self> {
        let capped = try_outcome!(<Capped<String>>::from_data(req, data).await);
        Success(capped.map(|s| s.into()))
    }
}

impl_strict_from_data_from_capped!(std::borrow::Cow<'_, str>);

#[crate::async_trait]
impl<'r> FromData<'r> for Capped<&'r [u8]> {
    type Error = std::io::Error;

    async fn from_data(req: &'r Request<'_>, data: Data<'r>) -> Outcome<'r, Self> {
        let capped = try_outcome!(<Capped<Vec<u8>>>::from_data(req, data).await);
        let raw = capped.map(|b| local_cache!(req, b));
        Success(raw)
    }
}

impl_strict_from_data_from_capped!(&'r [u8]);

#[crate::async_trait]
impl<'r> FromData<'r> for Capped<Vec<u8>> {
    type Error = std::io::Error;

    async fn from_data(req: &'r Request<'_>, data: Data<'r>) -> Outcome<'r, Self> {
        let limit = req.limits().get("bytes").unwrap_or(Limits::BYTES);
        data.open(limit).into_bytes().await.into_outcome(Status::BadRequest)
    }
}

impl_strict_from_data_from_capped!(Vec<u8>);

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

    async fn from_data(_: &'r Request<'_>, data: Data<'r>) -> Outcome<'r, Self> {
        Success(data)
    }
}

#[crate::async_trait]
impl<'r, T: FromData<'r> + 'r> FromData<'r> for Result<T, T::Error> {
    type Error = std::convert::Infallible;

    async fn from_data(req: &'r Request<'_>, data: Data<'r>) -> Outcome<'r, Self> {
        match T::from_data(req, data).await {
            Success(v) => Success(Ok(v)),
            Failure((_, e)) => Success(Err(e)),
            Forward(d) => Forward(d),
        }
    }
}

#[crate::async_trait]
impl<'r, T: FromData<'r>> FromData<'r> for Option<T> {
    type Error = std::convert::Infallible;

    async fn from_data(req: &'r Request<'_>, data: Data<'r>) -> Outcome<'r, Self> {
        match T::from_data(req, data).await {
            Success(v) => Success(Some(v)),
            Failure(..) | Forward(..) => Success(None),
        }
    }
}