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
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
#![cfg_attr(docsrs, feature(doc_auto_cfg, doc_cfg))]
#![doc = include_str!("../README.md")]
// @@ begin lint list maintained by maint/add_warning @@
#![cfg_attr(not(ci_arti_stable), allow(renamed_and_removed_lints))]
#![cfg_attr(not(ci_arti_nightly), allow(unknown_lints))]
#![warn(missing_docs)]
#![warn(noop_method_call)]
#![warn(unreachable_pub)]
#![warn(clippy::all)]
#![deny(clippy::await_holding_lock)]
#![deny(clippy::cargo_common_metadata)]
#![deny(clippy::cast_lossless)]
#![deny(clippy::checked_conversions)]
#![warn(clippy::cognitive_complexity)]
#![deny(clippy::debug_assert_with_mut_call)]
#![deny(clippy::exhaustive_enums)]
#![deny(clippy::exhaustive_structs)]
#![deny(clippy::expl_impl_clone_on_copy)]
#![deny(clippy::fallible_impl_from)]
#![deny(clippy::implicit_clone)]
#![deny(clippy::large_stack_arrays)]
#![warn(clippy::manual_ok_or)]
#![deny(clippy::missing_docs_in_private_items)]
#![warn(clippy::needless_borrow)]
#![warn(clippy::needless_pass_by_value)]
#![warn(clippy::option_option)]
#![deny(clippy::print_stderr)]
#![deny(clippy::print_stdout)]
#![warn(clippy::rc_buffer)]
#![deny(clippy::ref_option_ref)]
#![warn(clippy::semicolon_if_nothing_returned)]
#![warn(clippy::trait_duplication_in_bounds)]
#![deny(clippy::unnecessary_wraps)]
#![warn(clippy::unseparated_literal_suffix)]
#![deny(clippy::unwrap_used)]
#![allow(clippy::let_unit_value)] // This can reasonably be done for explicitness
#![allow(clippy::uninlined_format_args)]
#![allow(clippy::significant_drop_in_scrutinee)] // arti/-/merge_requests/588/#note_2812945
#![allow(clippy::result_large_err)] // temporary workaround for arti#587
#![allow(clippy::needless_raw_string_hashes)] // complained-about code is fine, often best
//! <!-- @@ end lint list maintained by maint/add_warning @@ -->

pub mod cmdline;
mod err;
mod flatten;
pub mod list_builder;
pub mod load;
mod misc;
mod mut_cfg;
mod path;
pub mod sources;

pub use cmdline::CmdLine;
pub use config as config_crate;
pub use educe;
pub use err::{ConfigBuildError, ConfigError, ReconfigureError};
pub use flatten::{Flatten, Flattenable};
pub use itertools::Itertools;
pub use list_builder::{MultilineListBuilder, MultilineListBuilderError};
pub use load::{resolve, resolve_ignore_warnings, resolve_return_results};
pub use misc::*;
pub use mut_cfg::MutCfg;
pub use paste::paste;
pub use path::{CfgPath, CfgPathError};
pub use serde;
pub use sources::{ConfigurationSource, ConfigurationSources};

pub use tor_basic_utils::macro_first_nonempty;

#[doc(hidden)]
pub use derive_adhoc;
#[doc(hidden)]
pub use flatten::flattenable_extract_fields;

/// Rules for reconfiguring a running Arti instance.
#[derive(Debug, Clone, Copy, Eq, PartialEq)]
#[non_exhaustive]
pub enum Reconfigure {
    /// Perform no reconfiguration unless we can guarantee that all changes will be successful.
    AllOrNothing,
    /// Try to reconfigure as much as possible; warn on fields that we cannot reconfigure.
    WarnOnFailures,
    /// Don't reconfigure anything: Only check whether we can guarantee that all changes will be successful.
    CheckAllOrNothing,
}

impl Reconfigure {
    /// Called when we see a disallowed attempt to change `field`: either give a ReconfigureError,
    /// or warn and return `Ok(())`, depending on the value of `self`.
    pub fn cannot_change<S: AsRef<str>>(self, field: S) -> Result<(), ReconfigureError> {
        match self {
            Reconfigure::AllOrNothing | Reconfigure::CheckAllOrNothing => {
                Err(ReconfigureError::CannotChange {
                    field: field.as_ref().to_owned(),
                })
            }
            Reconfigure::WarnOnFailures => {
                tracing::warn!("Cannot change {} on a running client.", field.as_ref());
                Ok(())
            }
        }
    }
}

/// Resolves an `Option<Option<T>>` (in a builder) into an `Option<T>`
///
///  * If the input is `None`, this indicates that the user did not specify a value,
///    and we therefore use `def` to obtain the default value.
///
///  * If the input is `Some(None)`, or `Some(Some(Default::default()))`,
///    the user has explicitly specified that this config item should be null/none/nothing,
///    so we return `None`.
///
///  * Otherwise the user provided an actual value, and we return `Some` of it.
///
/// See <https://gitlab.torproject.org/tpo/core/arti/-/issues/488>
///
/// For consistency with other APIs in Arti, when using this,
/// do not pass `setter(strip_option)` to derive_builder.
///
/// # ⚠ Stability Warning ⚠
///
/// We may significantly change this so that it is an method in an extension trait.
//
// This is an annoying AOI right now because you have to write things like
//     #[builder(field(build = r#"tor_config::resolve_option(&self.dns_port, || None)"#))]
//     pub(crate) dns_port: Option<u16>,
// which recapitulates the field name.  That is very much a bug hazard (indeed, in an
// early version of some of this code I perpetrated precisely that bug).
// Fixing this involves a derive_builder feature.
pub fn resolve_option<T, DF>(input: &Option<Option<T>>, def: DF) -> Option<T>
where
    T: Clone + Default + PartialEq,
    DF: FnOnce() -> Option<T>,
{
    resolve_option_general(
        input.as_ref().map(|ov| ov.as_ref()),
        |v| v == &T::default(),
        def,
    )
}

/// Resolves an `Option<Option<T>>` (in a builder) into an `Option<T>`, more generally
///
/// Like `resolve_option`, but:
///
///  * Doesn't rely on `T`' being `Default + PartialEq`
///    to determine whether it's the sentinel value;
///    instead, taking `is_explicit`.
///
///  * Takes `Option<Option<&T>>` which is more general, but less like the usual call sites.
///
///  * If the input is `None`, this indicates that the user did not specify a value,
///    and we therefore use `def` to obtain the default value.
///
///  * If the input is `Some(None)`, or `Some(Some(v)) where is_sentinel(v)`,
///    the user has explicitly specified that this config item should be null/none/nothing,
///    so we return `None`.
///
///  * Otherwise the user provided an actual value, and we return `Some` of it.
///
/// See <https://gitlab.torproject.org/tpo/core/arti/-/issues/488>
///
/// # ⚠ Stability Warning ⚠
///
/// We may significantly change this so that it is an method in an extension trait.
//
// TODO: it would be nice to have an example here, but right now I'm not sure
// what type (or config setting) we could put in an example that would be natural enough
// to add clarity.  See
//  https://gitlab.torproject.org/tpo/core/arti/-/merge_requests/685#note_2829951
pub fn resolve_option_general<T, ISF, DF>(
    input: Option<Option<&T>>,
    is_sentinel: ISF,
    def: DF,
) -> Option<T>
where
    T: Clone,
    DF: FnOnce() -> Option<T>,
    ISF: FnOnce(&T) -> bool,
{
    match input {
        None => def(),
        Some(None) => None,
        Some(Some(v)) if is_sentinel(v) => None,
        Some(Some(v)) => Some(v.clone()),
    }
}

/// Helper for resolving a config item which can be specified in multiple ways
///
/// Usable when a single configuration item can be specified
/// via multiple (alternative) input fields;
/// Each input field which is actually present
/// should be converted to the common output type,
/// and then passed to this function,
/// which will handle consistency checks and defaulting.
///
/// A common use case is deprecated field name/types.
/// In that case, the deprecated field names should be added to the appropriate
/// [`load::TopLevel::DEPRECATED_KEYS`].
///
/// `specified` should be an array (or other iterator) of `(key, Option<value>)`
/// where `key` is the field name and
/// `value` is that field from the builder,
/// converted to the common output type `V`.
///
/// # Example
///
/// ```
/// use derive_builder::Builder;
/// use serde::{Deserialize, Serialize};
/// use tor_config::{impl_standard_builder, ConfigBuildError, Listen, resolve_alternative_specs};
///
/// #[derive(Debug, Clone, Builder, Eq, PartialEq)]
/// #[builder(build_fn(error = "ConfigBuildError"))]
/// #[builder(derive(Debug, Serialize, Deserialize))]
/// #[allow(clippy::option_option)]
/// pub struct ProxyConfig {
///    /// Addresses to listen on for incoming SOCKS connections.
///    #[builder(field(build = r#"self.resolve_socks_port()?"#))]
///    pub(crate) socks_listen: Listen,
///
///    /// Port to listen on (at localhost) for incoming SOCKS
///    /// connections.
///    #[builder(setter(strip_option), field(type = "Option<Option<u16>>", build = "()"))]
///    pub(crate) socks_port: (),
/// }
/// impl_standard_builder! { ProxyConfig }
///
/// impl ProxyConfigBuilder {
///     fn resolve_socks_port(&self) -> Result<Listen, ConfigBuildError> {
///         resolve_alternative_specs(
///             [
///                 ("socks_listen", self.socks_listen.clone()),
///                 ("socks_port", self.socks_port.map(Listen::new_localhost_optional)),
///             ],
///             || Listen::new_localhost(9150),
///         )
///     }
/// }
/// ```
//
// Testing: this is tested quit exhaustively in the context of the listen/port handling, in
// crates/arti/src/cfg.rs.
pub fn resolve_alternative_specs<V, K>(
    specified: impl IntoIterator<Item = (K, Option<V>)>,
    default: impl FnOnce() -> V,
) -> Result<V, ConfigBuildError>
where
    K: Into<String>,
    V: Eq,
{
    Ok(specified
        .into_iter()
        .filter_map(|(k, v)| Some((k, v?)))
        .dedup_by(|(_, v1), (_, v2)| v1 == v2)
        .at_most_one()
        .map_err(|several| ConfigBuildError::Inconsistent {
            fields: several.into_iter().map(|(k, _v)| k.into()).collect_vec(),
            problem: "conflicting fields, specifying different values".into(),
        })?
        .map(|(_k, v)| v)
        .unwrap_or_else(default))
}

/// Defines standard impls for a struct with a `Builder`, incl `Default`
///
/// **Use this.**  Do not `#[derive(Builder, Default)]`.  That latter approach would produce
/// wrong answers if builder attributes are used to specify non-`Default` default values.
///
/// # Input syntax
///
/// ```
/// use derive_builder::Builder;
/// use serde::{Deserialize, Serialize};
/// use tor_config::impl_standard_builder;
/// use tor_config::ConfigBuildError;
///
/// #[derive(Debug, Builder, Clone, Eq, PartialEq)]
/// #[builder(derive(Serialize, Deserialize, Debug))]
/// #[builder(build_fn(error = "ConfigBuildError"))]
/// struct SomeConfigStruct { }
/// impl_standard_builder! { SomeConfigStruct }
///
/// #[derive(Debug, Builder, Clone, Eq, PartialEq)]
/// struct UnusualStruct { }
/// impl_standard_builder! { UnusualStruct: !Deserialize + !Builder }
/// ```
///
/// # Requirements
///
/// `$Config`'s builder must have default values for all the fields,
/// or this macro-generated self-test will fail.
/// This should be OK for all principal elements of our configuration.
///
/// `$ConfigBuilder` must have an appropriate `Deserialize` impl.
///
/// # Options
///
///  * `!Default` suppresses the `Default` implementation, and the corresponding tests.
///    This should be done within Arti's configuration only for sub-structures which
///    contain mandatory fields (and are themselves optional).
///
///  * `!Deserialize` suppresses the test case involving `Builder: Deserialize`.
///    This should not be done for structs which are part of Arti's configuration,
///    but can be appropriate for other types that use [`derive_builder`].
///
///  * `!Builder` suppresses the impl of the [`tor_config::load::Builder`](load::Builder) trait
///    This will be necessary if the error from the builder is not [`ConfigBuildError`].
///
/// # Generates
///
///  * `impl Default for $Config`
///  * `impl Builder for $ConfigBuilder`
///  * a self-test that the `Default` impl actually works
///  * a test that the `Builder` can be deserialized from an empty [`config::Config`],
///    and then built, and that the result is the same as the ordinary default.
//
// The implementation munches fake "trait bounds" (`: !Deserialize + !Wombat ...`) off the RHS.
// We're going to add at least one more option.
//
// When run with `!Default`, this only generates a `builder` impl and an impl of
// the `Resolvable` trait which probably won't be used anywhere.  That may seem
// like a poor tradeoff (much fiddly macro code to generate a trivial function in
// a handful of call sites).  However, this means that `impl_standard_builder!`
// can be used in more places.  That sets a good example: always use the macro.
//
// That is a good example because we want `impl_standard_builder!` to be
// used elsewhere because it generates necessary tests of properties
// which might otherwise be violated.  When adding code, people add according to the
// patterns they see.
//
// (We, sadly, don't have a good way to *ensure* use of `impl_standard_builder`.)
#[macro_export]
macro_rules! impl_standard_builder {
    // Convert the input into the "being processed format":
    {
        $Config:ty $(: $($options:tt)* )?
    } => { $crate::impl_standard_builder!{
        // ^Being processed format:
        @ ( Builder                    )
          ( default                    )
          ( try_deserialize            ) $Config    :                 $( $( $options    )* )?
        //  ~~~~~~~~~~~~~~~              ^^^^^^^    ^   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        // present iff not !Builder, !Default
        // present iff not !Default
        // present iff not !Deserialize  type      always present    options yet to be parsed
    } };
    // If !Deserialize is the next option, implement it by making $try_deserialize absent
    {
        @ ( $($Builder        :ident)? )
          ( $($default        :ident)? )
          ( $($try_deserialize:ident)? ) $Config:ty : $(+)? !Deserialize $( $options:tt )*
    } => {  $crate::impl_standard_builder!{
        @ ( $($Builder              )? )
          ( $($default              )? )
          (                            ) $Config    :                    $( $options    )*
    } };
    // If !Builder is the next option, implement it by making $Builder absent
    {
        @ ( $($Builder        :ident)? )
          ( $($default        :ident)? )
          ( $($try_deserialize:ident)? ) $Config:ty : $(+)? !Builder     $( $options:tt )*
    } => {  $crate::impl_standard_builder!{
        @ (                            )
          ( $($default              )? )
          ( $($try_deserialize      )? ) $Config    :                    $( $options    )*
    } };
    // If !Default is the next option, implement it by making $default absent
    {
        @ ( $($Builder        :ident)? )
          ( $($default        :ident)? )
          ( $($try_deserialize:ident)? ) $Config:ty : $(+)? !Default     $( $options:tt )*
    } => {  $crate::impl_standard_builder!{
        @ ( $($Builder              )? )
          (                            )
          ( $($try_deserialize      )? ) $Config    :                    $( $options    )*
    } };
    // Having parsed all options, produce output:
    {
        @ ( $($Builder        :ident)? )
          ( $($default        :ident)? )
          ( $($try_deserialize:ident)? ) $Config:ty : $(+)?
    } => { $crate::paste!{
        impl $Config {
            /// Returns a fresh, default, builder
            pub fn builder() -> [< $Config Builder >] {
                Default::default()
            }
        }

        $( // expands iff there was $default, which is always default
            impl Default for $Config {
                fn $default() -> Self {
                    // unwrap is good because one of the test cases above checks that it works!
                    [< $Config Builder >]::default().build().unwrap()
                }
            }
        )?

        $( // expands iff there was $Builder, which is always Builder
            impl $crate::load::$Builder for [< $Config Builder >] {
                type Built = $Config;
                fn build(&self) -> std::result::Result<$Config, $crate::ConfigBuildError> {
                    [< $Config Builder >]::build(self)
                }
            }
        )?

        #[test]
        #[allow(non_snake_case)]
        fn [< test_impl_Default_for_ $Config >] () {
            #[allow(unused_variables)]
            let def = None::<$Config>;
            $( // expands iff there was $default, which is always default
                let def = Some($Config::$default());
            )?

            if let Some(def) = def {
                $( // expands iff there was $try_deserialize, which is always try_deserialize
                    let empty_config = $crate::config_crate::Config::builder().build().unwrap();
                    let builder: [< $Config Builder >] = empty_config.$try_deserialize().unwrap();
                    let from_empty = builder.build().unwrap();
                    assert_eq!(def, from_empty);
                )*
            }
        }
    } };
}

#[cfg(test)]
mod test {
    // @@ begin test lint list maintained by maint/add_warning @@
    #![allow(clippy::bool_assert_comparison)]
    #![allow(clippy::clone_on_copy)]
    #![allow(clippy::dbg_macro)]
    #![allow(clippy::print_stderr)]
    #![allow(clippy::print_stdout)]
    #![allow(clippy::single_char_pattern)]
    #![allow(clippy::unwrap_used)]
    #![allow(clippy::unchecked_duration_subtraction)]
    #![allow(clippy::useless_vec)]
    #![allow(clippy::needless_pass_by_value)]
    //! <!-- @@ end test lint list maintained by maint/add_warning @@ -->
    use super::*;
    use crate as tor_config;
    use derive_builder::Builder;
    use serde::{Deserialize, Serialize};
    use serde_json::json;
    use tracing_test::traced_test;

    #[test]
    #[traced_test]
    fn reconfigure_helpers() {
        let how = Reconfigure::AllOrNothing;
        let err = how.cannot_change("the_laws_of_physics").unwrap_err();
        assert_eq!(
            err.to_string(),
            "Cannot change the_laws_of_physics on a running client.".to_owned()
        );

        let how = Reconfigure::WarnOnFailures;
        let ok = how.cannot_change("stuff");
        assert!(ok.is_ok());
        assert!(logs_contain("Cannot change stuff on a running client."));
    }

    #[test]
    #[rustfmt::skip] // autoformatting obscures the regular structure
    fn resolve_option_test() {
        #[derive(Debug, Clone, Builder, Eq, PartialEq)]
        #[builder(build_fn(error = "ConfigBuildError"))]
        #[builder(derive(Debug, Serialize, Deserialize, Eq, PartialEq))]
        struct TestConfig {
            #[builder(field(build = r#"tor_config::resolve_option(&self.none, || None)"#))]
            none: Option<u32>,

            #[builder(field(build = r#"tor_config::resolve_option(&self.four, || Some(4))"#))]
            four: Option<u32>,
        }

        // defaults
        {
            let builder_from_json: TestConfigBuilder = serde_json::from_value(
                json!{ { } }
            ).unwrap();

            let builder_from_methods = TestConfigBuilder::default();

            assert_eq!(builder_from_methods, builder_from_json);
            assert_eq!(builder_from_methods.build().unwrap(),
                        TestConfig { none: None, four: Some(4) });
        }

        // explicit positive values
        {
            let builder_from_json: TestConfigBuilder = serde_json::from_value(
                json!{ { "none": 123, "four": 456 } }
            ).unwrap();

            let mut builder_from_methods = TestConfigBuilder::default();
            builder_from_methods.none(Some(123));
            builder_from_methods.four(Some(456));

            assert_eq!(builder_from_methods, builder_from_json);
            assert_eq!(builder_from_methods.build().unwrap(),
                       TestConfig { none: Some(123), four: Some(456) });
        }

        // explicit "null" values
        {
            let builder_from_json: TestConfigBuilder = serde_json::from_value(
                json!{ { "none": 0, "four": 0 } }
            ).unwrap();

            let mut builder_from_methods = TestConfigBuilder::default();
            builder_from_methods.none(Some(0));
            builder_from_methods.four(Some(0));

            assert_eq!(builder_from_methods, builder_from_json);
            assert_eq!(builder_from_methods.build().unwrap(),
                       TestConfig { none: None, four: None });
        }

        // explicit None (API only, serde can't do this for Option)
        {
            let mut builder_from_methods = TestConfigBuilder::default();
            builder_from_methods.none(None);
            builder_from_methods.four(None);

            assert_eq!(builder_from_methods.build().unwrap(),
                       TestConfig { none: None, four: None });
        }
    }
}