tor_netdoc/parse2/traits.rs
1//! Core model for netdoc parsing
2
3use super::*;
4
5/// A document or section that can be parsed
6///
7/// Normally [derived](derive_deftly_template_NetdocParseable).
8pub trait NetdocParseable: Sized {
9 /// Document type for errors, normally its intro keyword
10 fn doctype_for_error() -> &'static str;
11
12 /// Is `Keyword` an intro Item Keyword for this kind of document?
13 ///
14 /// This is used with 1-keyword lookahead, to allow us to push or pop
15 /// the parsing state into or out of a sub-document.
16 ///
17 /// For signatures sections, this should report *every* recognised keyword.
18 fn is_intro_item_keyword(kw: KeywordRef<'_>) -> bool;
19
20 /// Parse the document from a stream of Items
21 ///
22 /// Should stop before reading any keyword matching `stop_at`.
23 /// (Except, right at the start.)
24 ///
25 /// Should also stop before reading a 2nd intro keyword,
26 /// so that successive calls to this function can parse
27 /// successive sub-documents of this kind.
28 ///
29 /// Otherwise, should continue until EOF.
30 ///
31 /// Must check whether the first item is this document's `is_intro_item_keyword`,
32 /// and error if not.
33 fn from_items(input: &mut ItemStream<'_>, stop_at: stop_at!()) -> Result<Self, ErrorProblem>;
34
35 /// Is `Keyword` a structural keyword for this kind of document?
36 ///
37 /// Returns `Some(IsStructural)` for:
38 /// - this type's intro item keyword (`is_intro_item_keyword`)
39 /// - the intro items or structural items for any of its sub-documents and sections
40 /// `#[deftly(netdoc(subdoc))]`
41 ///
42 /// (This means it returns true for *any* item in a signatures subdocument
43 /// ie any field in a struct decorated `#[deftly(netdoc(signatures))]`
44 /// since those are considered intro items.)
45 ///
46 /// Used for avoiding parsing ambiguity when a netdoc from a semi-trusted source
47 /// is embedded into another netdoc.
48 /// See <https://spec.torproject.org/dir-spec/creating-key-certificates.html#nesting>.
49 ///
50 /// # Return type and relationship to `is_intro_item_keyword`
51 ///
52 /// Returns `Option<IsStructural>`
53 /// so that it has a different type to [`NetdocParseable::is_intro_item_keyword`],
54 /// preventing accidental confusion between the two kinds of keyword property enquiry.
55 ///
56 /// Our parsing algorithms actually only care about *intro keywords* for sub-documents.
57 /// We don't need to worry about anything else;
58 /// notably, we don't need to care about other structural items within those sub-documents.
59 ///
60 /// Except for authcerts in votes,, which are nested documents
61 /// with partially trusted content.
62 /// That is what this method is for.
63 ///
64 /// So, we privilege `is_intro_item_keyword` by having it return `bool`
65 /// and by the affordances in [`StopAt`].
66 fn is_structural_keyword(kw: KeywordRef<'_>) -> Option<IsStructural>;
67}
68
69/// A collection of fields that can be parsed within a section
70///
71/// None of the items can be structural.
72///
73/// Normally [derived](derive_deftly_template_NetdocParseableFields).
74pub trait NetdocParseableFields: Sized {
75 /// The partially-parsed set of items.
76 type Accumulator: Sized + Debug + Send + Sync + 'static;
77
78 /// Is this one of the keywords in this struct
79 fn is_item_keyword(kw: KeywordRef<'_>) -> bool;
80
81 /// Accumulate an item in this struct
82 ///
83 /// # Panics
84 ///
85 /// The caller must have first checked the `item`'s keyword with `is_item_keyword`.
86 /// If this *isn't* an item for this structure, may panic.
87 fn accumulate_item(acc: &mut Self::Accumulator, item: UnparsedItem<'_>) -> Result<(), EP>;
88
89 /// Finish
90 ///
91 /// Resolves the `Accumulator` into the output type.
92 /// Generally, this means throwing an error if expected fields were not present.
93 fn finish(acc: Self::Accumulator) -> Result<Self, EP>;
94}
95
96/// An item (value) that can be parsed in a netdoc
97///
98/// This is the type `T` of a field `item: T` in a netdoc type.
99///
100/// An implementation is provided for tuples of `ItemArgumentParseable`,
101/// which parses each argument in turn,
102/// ignores additional arguments,
103/// and rejects any Object.
104///
105/// Typically derived with
106/// [`#[derive_deftly(ItemValueParseable)]`](derive_deftly_template_ItemValueParseable).
107///
108/// Signature items are special, and implement [`SignatureItemParseable`] instead.
109pub trait ItemValueParseable: Sized {
110 /// Parse the item's value
111 fn from_unparsed(item: UnparsedItem<'_>) -> Result<Self, ErrorProblem>;
112}
113
114/// An (individual) argument that can be parsed from in a netdoc
115///
116/// An implementations is provided for **`T: FromStr`**,
117/// which expects a single argument and passes it to `FromStr`.
118///
119/// For netdoc arguments whose specified syntax spans multiple space-separated words,
120/// use a manual implementation or a wrapper type.
121pub trait ItemArgumentParseable: Sized {
122 /// Parse the argument
123 fn from_args<'s>(args: &mut ArgumentStream<'s>) -> Result<Self, ArgumentError>;
124}
125
126/// An Object value that be parsed from a netdoc
127pub trait ItemObjectParseable: Sized {
128 /// Check that the Label is right
129 fn check_label(label: &str) -> Result<(), ErrorProblem>;
130
131 /// Convert the bytes of the Object (which was present) into the actual value
132 ///
133 /// `input` has been base64-decoded.
134 fn from_bytes(input: &[u8]) -> Result<Self, ErrorProblem>;
135}
136
137/// Token indicating that a keyword is structural
138///
139/// Returned by [`NetdocParseable::is_structural_keyword`]
140#[derive(Copy, Clone, Debug, Eq, PartialEq, Ord, PartialOrd, Hash)]
141#[allow(clippy::exhaustive_structs)]
142pub struct IsStructural;
143
144//---------- provided blanket impls ----------
145
146impl<T: ItemArgumentParseable> ItemArgumentParseable for Arc<T> {
147 fn from_args<'s>(args: &mut ArgumentStream<'s>) -> Result<Self, ArgumentError> {
148 T::from_args(args).map(Arc::new)
149 }
150}
151
152impl<T: NormalItemArgument + FromStr> ItemArgumentParseable for T {
153 fn from_args<'s>(args: &mut ArgumentStream<'s>) -> Result<Self, AE> {
154 let v = args
155 .next()
156 .ok_or(AE::Missing)?
157 .parse()
158 .map_err(|_e| AE::Invalid)?;
159 Ok(v)
160 }
161}
162
163impl<T: ItemValueParseable> ItemValueParseable for Arc<T> {
164 fn from_unparsed(item: UnparsedItem<'_>) -> Result<Self, ErrorProblem> {
165 T::from_unparsed(item).map(Arc::new)
166 }
167}
168
169impl<T: NetdocParseable> NetdocParseable for Arc<T> {
170 fn doctype_for_error() -> &'static str {
171 T::doctype_for_error()
172 }
173 fn is_intro_item_keyword(kw: KeywordRef<'_>) -> bool {
174 T::is_intro_item_keyword(kw)
175 }
176 fn is_structural_keyword(kw: KeywordRef<'_>) -> Option<IsStructural> {
177 T::is_structural_keyword(kw)
178 }
179 fn from_items(input: &mut ItemStream<'_>, stop_at: stop_at!()) -> Result<Self, EP> {
180 T::from_items(input, stop_at).map(Arc::new)
181 }
182}
183impl<T: NetdocParseableFields> NetdocParseableFields for Arc<T> {
184 type Accumulator = T::Accumulator;
185 fn is_item_keyword(kw: KeywordRef<'_>) -> bool {
186 T::is_item_keyword(kw)
187 }
188 fn accumulate_item(acc: &mut Self::Accumulator, item: UnparsedItem<'_>) -> Result<(), EP> {
189 T::accumulate_item(acc, item)
190 }
191 fn finish(acc: Self::Accumulator) -> Result<Self, EP> {
192 T::finish(acc).map(Arc::new)
193 }
194}
195
196/// implement [`ItemValueParseable`] for a particular tuple size
197macro_rules! item_value_parseable_for_tuple {
198 { $($i:literal)* } => { paste! {
199 impl< $( [<T$i>]: ItemArgumentParseable, )* >
200 ItemValueParseable for ( $( [<T$i>], )* )
201 {
202 fn from_unparsed(
203 #[allow(unused_mut)]
204 mut item: UnparsedItem<'_>,
205 ) -> Result<Self, ErrorProblem> {
206 let r = ( $(
207 <[<T$i>] as ItemArgumentParseable>::from_args(
208 item.args_mut(),
209 ).map_err(item.args().error_handler(stringify!($i)))?,
210 )* );
211 item.check_no_object()?;
212 Ok(r)
213 }
214 }
215 } }
216}
217
218item_value_parseable_for_tuple! {}
219item_value_parseable_for_tuple! { 0 }
220item_value_parseable_for_tuple! { 0 1 }
221item_value_parseable_for_tuple! { 0 1 2 }
222item_value_parseable_for_tuple! { 0 1 2 3 }
223item_value_parseable_for_tuple! { 0 1 2 3 4 }
224item_value_parseable_for_tuple! { 0 1 2 3 4 5 }
225item_value_parseable_for_tuple! { 0 1 2 3 4 5 6 }
226item_value_parseable_for_tuple! { 0 1 2 3 4 5 6 7 }
227item_value_parseable_for_tuple! { 0 1 2 3 4 5 6 7 8 }
228item_value_parseable_for_tuple! { 0 1 2 3 4 5 6 7 8 9 }