chore: update Cargo.lock

Documentation and unit tests

Cargo.toml

@@ -47,7 +47,7 @@ memsec = { git = "https://github.com/rosenpass/memsec.git", rev = "aceb9baee8aec
 rand = "0.8.5"
 typenum = "1.17.0"
 log = { version = "0.4.22" }
-clap = { version = "4.5.19", features = ["derive"] }
+clap = { version = "4.5.20", features = ["derive"] }
 serde = { version = "1.0.210", features = ["derive"] }
 arbitrary = { version = "1.3.2", features = ["derive"] }
 anyhow = { version = "1.0.89", features = ["backtrace", "std"] }

constant-time/src/compare.rs

@@ -1,7 +1,15 @@
+//! Constant-time comparison
+
 use core::ptr;
 
 /// Little endian memcmp version of quinier/memsec
 /// https://github.com/quininer/memsec/blob/bbc647967ff6d20d6dccf1c85f5d9037fcadd3b0/src/lib.rs#L30
+///
+/// # Panic & Safety
+///
+/// Both input arrays must be at least of the indicated length.
+///
+/// See [std::ptr::read_volatile] on safety.
 #[inline(never)]
 pub unsafe fn memcmp_le(b1: *const u8, b2: *const u8, len: usize) -> i32 {
     let mut res = 0;
@@ -13,6 +21,16 @@ pub unsafe fn memcmp_le(b1: *const u8, b2: *const u8, len: usize) -> i32 {
     ((res - 1) >> 8) + (res >> 8) + 1
 }
 
+#[test]
+pub fn memcmp_le_test() {
+    // use rosenpass_constant_time::memcmp_le;
+    let a = [0, 1, 0, 0];
+    let b = [0, 0, 0, 1];
+    assert_eq!(-1, unsafe { memcmp_le(a.as_ptr(), b.as_ptr(), 4) });
+    assert_eq!(0, unsafe { memcmp_le(a.as_ptr(), a.as_ptr(), 4) });
+    assert_eq!(1, unsafe { memcmp_le(b.as_ptr(), a.as_ptr(), 4) });
+}
+
 /// compares two slices of memory content and returns an integer indicating the relationship between
 /// the slices
 ///
@@ -32,6 +50,28 @@ pub unsafe fn memcmp_le(b1: *const u8, b2: *const u8, len: usize) -> i32 {
 /// ## Tests
 /// For discussion on how to ensure the constant-time execution of this function, see
 /// <https://github.com/rosenpass/rosenpass/issues/232>
+///
+/// # Examples
+///
+/// ```rust
+/// use rosenpass_constant_time::compare;
+/// let a = [0, 1, 0, 0];
+/// let b = [0, 0, 0, 1];
+/// assert_eq!(-1, compare(&a, &b));
+/// assert_eq!(0, compare(&a, &a));
+/// assert_eq!(1, compare(&b, &a));
+/// ```
+///
+/// # Panic
+///
+/// This function will panic if the input arrays are of different lengths.
+///
+/// ```should_panic
+/// use rosenpass_constant_time::compare;
+/// let a = [0, 1, 0];
+/// let b = [0, 0, 0, 1];
+/// compare(&a, &b);
+/// ```
 #[inline]
 pub fn compare(a: &[u8], b: &[u8]) -> i32 {
     assert!(a.len() == b.len());

constant-time/src/increment.rs

@@ -1,3 +1,5 @@
+//! Incrementing numbers
+
 use core::hint::black_box;
 
 /// Interpret the given slice as a little-endian unsigned integer

constant-time/src/lib.rs

@@ -1,3 +1,5 @@
+#![warn(missing_docs)]
+#![warn(clippy::missing_docs_in_private_items)]
 //! constant-time implementations of some primitives
 //!
 //! Rosenpass internal library providing basic constant-time operations.

constant-time/src/memcmp.rs

@@ -1,3 +1,5 @@
+//! memcmp
+
 /// compares two sclices of memory content and returns whether they are equal
 ///
 /// ## Leaks
@@ -7,6 +9,18 @@
 ///
 /// The execution time of the function grows approx. linear with the length of the input. This is
 /// considered safe.
+///
+/// ## Examples
+///
+/// ```rust
+/// use rosenpass_constant_time::memcmp;
+/// let a = [0, 0, 0, 0];
+/// let b = [0, 0, 0, 1];
+/// let c = [0, 0, 0];
+/// assert!(memcmp(&a, &a));
+/// assert!(!memcmp(&a, &b));
+/// assert!(!memcmp(&a, &c));
+/// ```
 #[inline]
 pub fn memcmp(a: &[u8], b: &[u8]) -> bool {
     a.len() == b.len() && unsafe { memsec::memeq(a.as_ptr(), b.as_ptr(), a.len()) }

constant-time/src/xor.rs

@@ -1,3 +1,5 @@
+//! xor
+
 use core::hint::black_box;
 use rosenpass_to::{with_destination, To};
 

oqs/Cargo.toml

@@ -14,3 +14,7 @@ rosenpass-cipher-traits = { workspace = true }
 rosenpass-util = { workspace = true }
 oqs-sys = { workspace = true }
 paste = { workspace = true }
+
+[dev-dependencies]
+rosenpass-secret-memory = { workspace = true }
+rosenpass-constant-time = { workspace = true }

oqs/src/kem_macro.rs

@@ -1,9 +1,42 @@
+//! Generic helpers for declaring bindings to liboqs kems
+
+/// Generate bindings to a liboqs-provided KEM
 macro_rules! oqs_kem {
     ($name:ident) => { ::paste::paste!{
+        #[doc = "Bindings for ::oqs_sys::kem::" [<"OQS_KEM" _ $name:snake>] "_*"]
         mod [< $name:snake >] {
             use rosenpass_cipher_traits::Kem;
             use rosenpass_util::result::Guaranteed;
 
+            #[doc = "Bindings for ::oqs_sys::kem::" [<"OQS_KEM" _ $name:snake>] "_*"]
+            #[doc = ""]
+            #[doc = "# Examples"]
+            #[doc = ""]
+            #[doc = "```rust"]
+            #[doc = "use std::borrow::{Borrow, BorrowMut};"]
+            #[doc = "use rosenpass_cipher_traits::Kem;"]
+            #[doc = "use rosenpass_oqs::" $name:camel " as MyKem;"]
+            #[doc = "use rosenpass_secret_memory::{Secret, Public};"]
+            #[doc = ""]
+            #[doc = "rosenpass_secret_memory::secret_policy_try_use_memfd_secrets();"]
+            #[doc = ""]
+            #[doc = "// Recipient generates secret key, transfers pk to sender"]
+            #[doc = "let mut sk = Secret::<{ MyKem::SK_LEN }>::zero();"]
+            #[doc = "let mut pk = Public::<{ MyKem::PK_LEN }>::zero();"]
+            #[doc = "MyKem::keygen(sk.secret_mut(), pk.borrow_mut());"]
+            #[doc = ""]
+            #[doc = "// Sender generates ciphertext and local shared key, sends ciphertext to recipient"]
+            #[doc = "let mut shk_enc = Secret::<{ MyKem::SHK_LEN }>::zero();"]
+            #[doc = "let mut ct = Public::<{ MyKem::CT_LEN }>::zero();"]
+            #[doc = "MyKem::encaps(shk_enc.secret_mut(), ct.borrow_mut(), pk.borrow());"]
+            #[doc = ""]
+            #[doc = "// Recipient decapsulates ciphertext"]
+            #[doc = "let mut shk_dec = Secret::<{ MyKem::SHK_LEN }>::zero();"]
+            #[doc = "MyKem::decaps(shk_dec.secret_mut(), sk.secret(), ct.borrow());"]
+            #[doc = ""]
+            #[doc = "// Both parties end up with the same shared key"]
+            #[doc = "assert!(rosenpass_constant_time::compare(shk_enc.secret_mut(), shk_dec.secret_mut()) == 0);"]
+            #[doc = "```"]
             pub enum [< $name:camel >]  {}
 
             /// # Panic & Safety

oqs/src/lib.rs

@@ -1,3 +1,8 @@
+#![warn(missing_docs)]
+#![warn(clippy::missing_docs_in_private_items)]
+//! Bindings for liboqs used in Rosenpass
+
+/// Call into a libOQS function
 macro_rules! oqs_call {
     ($name:path, $($args:expr),*) => {{
         use oqs_sys::common::OQS_STATUS::*;

rosenpass/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "rosenpass"
-version = "0.2.1"
+version = "0.3.0-dev"
 authors = ["Karolin Varner <karo@cupdev.net>", "wucke13 <wucke13@gmail.com>"]
 edition = "2021"
 license = "MIT OR Apache-2.0"

rosenpass/src/app_server.rs

@@ -154,7 +154,6 @@ pub struct AppServerTest {
 #[derive(Debug, PartialEq, Eq, Copy, Clone)]
 pub enum AppServerIoSource {
     Socket(usize),
-    #[cfg(feature = "experiment_api")]
     PskBroker(Public<BROKER_ID_BYTES>),
     #[cfg(feature = "experiment_api")]
     MioManager(crate::api::mio::MioManagerIoSource),
@@ -1209,15 +1208,12 @@ impl AppServer {
         buf: &mut [u8],
         io_source: AppServerIoSource,
     ) -> anyhow::Result<Option<(usize, Endpoint)>> {
-        use crate::api::mio::MioManagerContext;
-
         match io_source {
             AppServerIoSource::Socket(idx) => self
                 .try_recv_from_listen_socket(buf, idx)
                 .substitute_for_ioerr_wouldblock(None)?
                 .ok(),
 
-            #[cfg(feature = "experiment_api")]
             AppServerIoSource::PskBroker(key) => self
                 .brokers
                 .store
@@ -1227,9 +1223,13 @@ impl AppServer {
                 .map(|_| None),
 
             #[cfg(feature = "experiment_api")]
-            AppServerIoSource::MioManager(mmio_src) => MioManagerFocus(self)
-                .poll_particular(mmio_src)
-                .map(|_| None),
+            AppServerIoSource::MioManager(mmio_src) => {
+                use crate::api::mio::MioManagerContext;
+
+                MioManagerFocus(self)
+                    .poll_particular(mmio_src)
+                    .map(|_| None)
+            }
         }
     }
 

util/src/b64.rs

@@ -1,8 +1,13 @@
+//! Utilities for working with Base64
+
 use base64ct::{Base64, Decoder as B64Reader, Encoder as B64Writer};
 use zeroize::Zeroize;
 
 use std::fmt::Display;
 
+/// Formatter that displays its input as base64.
+///
+/// Use through [B64Display].
 pub struct B64DisplayHelper<'a, const F: usize>(&'a [u8]);
 
 impl<const F: usize> Display for B64DisplayHelper<'_, F> {
@@ -15,7 +20,25 @@ impl<const F: usize> Display for B64DisplayHelper<'_, F> {
     }
 }
 
+/// Extension trait that can be used to display values as Base64
+///
+/// # Examples
+///
+/// ```
+/// use rosenpass_util::b64::B64Display;
+///
+/// let a = vec![0,1,2,3,4,5];
+/// assert_eq!(
+///   format!("{}", a.fmt_b64::<10>()), // Maximum size of the encoded buffer
+///   "AAECAwQF",
+/// );
+/// ```
 pub trait B64Display {
+    /// Display this value as base64
+    ///
+    /// # Examples
+    ///
+    /// See [B64Display].
     fn fmt_b64<const F: usize>(&self) -> B64DisplayHelper<F>;
 }
 
@@ -31,6 +54,11 @@ impl<T: AsRef<[u8]>> B64Display for T {
     }
 }
 
+/// Decode a base64-encoded value
+///
+/// # Examples
+///
+/// See [b64_encode].
 pub fn b64_decode(input: &[u8], output: &mut [u8]) -> anyhow::Result<()> {
     let mut reader = B64Reader::<Base64>::new(input).map_err(|e| anyhow::anyhow!(e))?;
     match reader.decode(output) {
@@ -49,6 +77,23 @@ pub fn b64_decode(input: &[u8], output: &mut [u8]) -> anyhow::Result<()> {
     }
 }
 
+/// Encode a value as base64.
+///
+/// ```
+/// use rosenpass_util::b64::{b64_encode, b64_decode};
+///
+/// let bytes = b"Hello World";
+///
+/// let mut encoder_buffer = [0u8; 64];
+/// let encoded = b64_encode(bytes, &mut encoder_buffer)?;
+///
+/// let mut bytes_decoded = [0u8; 11];
+/// b64_decode(encoded.as_bytes(), &mut bytes_decoded);
+/// assert_eq!(bytes, &bytes_decoded);
+///
+/// Ok::<(), anyhow::Error>(())
+/// ```
+///
 pub fn b64_encode<'o>(input: &[u8], output: &'o mut [u8]) -> anyhow::Result<&'o str> {
     let mut writer = B64Writer::<Base64>::new(output).map_err(|e| anyhow::anyhow!(e))?;
     writer.encode(input).map_err(|e| anyhow::anyhow!(e))?;

util/src/build.rs

@@ -1,33 +1,163 @@
+//! Lazy construction of values
+
 use crate::{
     functional::ApplyExt,
     mem::{SwapWithDefaultExt, SwapWithExt},
 };
 
-#[derive(thiserror::Error, Debug)]
+/// Errors returned by [ConstructionSite::erect]
+#[derive(thiserror::Error, Debug, Eq, PartialEq)]
 pub enum ConstructionSiteErectError<E> {
+    /// Attempted to erect an empty construction site
     #[error("Construction site is void")]
     IsVoid,
+    /// Attempted to erect a construction that is already standing
     #[error("Construction is already built")]
     AlreadyBuilt,
+    /// Other error
     #[error("Other construction site error {0:?}")]
     Other(#[from] E),
 }
 
+/// A type that can build some other type
+///
+/// # Examples
+///
+/// ```
+/// use rosenpass_util::build::Build;
+/// use anyhow::{Context, Result};
+///
+/// #[derive(Eq, PartialEq, Debug)]
+/// struct Person {
+///     pub fav_pokemon: String,
+///     pub fav_number: u8,
+/// }
+///
+/// #[derive(Default, Clone)]
+/// struct PersonBuilder {
+///     pub fav_pokemon: Option<String>,
+///     pub fav_number: Option<u8>,
+/// }
+///
+/// impl Build<Person> for &PersonBuilder {
+///     type Error = anyhow::Error;
+///
+///     fn build(self) -> Result<Person, Self::Error> {
+///         let fav_pokemon = self.fav_pokemon.clone().context("Missing fav pokemon")?;
+///         let fav_number = self.fav_number.context("Missing fav number")?;
+///         Ok(Person {
+///             fav_pokemon,
+///             fav_number,
+///         })
+///     }
+/// }
+///
+/// let mut person_builder = PersonBuilder::default();
+/// assert!(person_builder.build().is_err());
+///
+/// person_builder.fav_pokemon = Some("Krabby".to_owned());
+/// person_builder.fav_number = Some(0);
+/// assert_eq!(
+///     person_builder.build().unwrap(),
+///     Person {
+///         fav_pokemon: "Krabby".to_owned(),
+///         fav_number: 0
+///     }
+/// );
+/// ```
 pub trait Build<T>: Sized {
+    /// Error returned by the builder
     type Error;
+    /// Build the type
+    ///
+    /// # Examples
+    ///
+    /// See [Self].
     fn build(self) -> Result<T, Self::Error>;
 }
 
-#[derive(Debug)]
+/// A type that can be incrementally built from a type that can [Build] it
+///
+/// This is similar to an option, where [Self::Void] is [std::Option::None],
+/// [Self::Product] is [std::Option::Some], except that there is a third
+/// intermediate state [Self::Builder] that represents a Some/Product value
+/// in the process of being made.
+///
+/// # Examples
+///
+/// ```
+/// use std::borrow::Borrow;
+/// use rosenpass_util::build::{ConstructionSite, Build};
+/// use anyhow::{Context, Result};
+///
+/// #[derive(Eq, PartialEq, Debug)]
+/// struct Person {
+///     pub fav_pokemon: String,
+///     pub fav_number: u8,
+/// }
+///
+/// #[derive(Eq, PartialEq, Default, Clone, Debug)]
+/// struct PersonBuilder {
+///     pub fav_pokemon: Option<String>,
+///     pub fav_number: Option<u8>,
+/// }
+///
+/// impl Build<Person> for &PersonBuilder {
+///     type Error = anyhow::Error;
+///
+///     fn build(self) -> Result<Person, Self::Error> {
+///         let fav_pokemon = self.fav_pokemon.clone().context("Missing fav pokemon")?;
+///         let fav_number = self.fav_number.context("Missing fav number")?;
+///         Ok(Person {
+///             fav_pokemon,
+///             fav_number,
+///         })
+///     }
+/// }
+///
+/// impl Build<Person> for PersonBuilder {
+///     type Error = anyhow::Error;
+///
+///     fn build(self) -> Result<Person, Self::Error> {
+///          self.borrow().build()
+///     }
+/// }
+///
+/// // Allocate the construction site
+/// let mut site = ConstructionSite::void();
+///
+/// // Start construction
+/// site = ConstructionSite::Builder(PersonBuilder::default());
+///
+/// // Use the builder to build the value
+/// site.builder_mut().unwrap().fav_pokemon = Some("Krabby".to_owned());
+/// site.builder_mut().unwrap().fav_number = Some(0);
+///
+/// // Use `erect` to call Build::build
+/// site.erect();
+///
+/// assert_eq!(
+///     site,
+///     ConstructionSite::Product(Person {
+///         fav_pokemon: "Krabby".to_owned(),
+///         fav_number: 0
+///     }),
+/// );
+/// ```
+#[derive(Debug, Eq, PartialEq, Clone)]
 pub enum ConstructionSite<Builder, T>
 where
     Builder: Build<T>,
 {
+    /// The site is empty
     Void,
+    /// The site is being built
     Builder(Builder),
+    /// The site has been built and is now finished
     Product(T),
 }
 
+/// Initializes the construction site as [ConstructionSite::Void]
 impl<Builder, T> Default for ConstructionSite<Builder, T>
 where
     Builder: Build<T>,
@@ -41,22 +171,189 @@ impl<Builder, T> ConstructionSite<Builder, T>
 where
     Builder: Build<T>,
 {
+    /// Initializes the construction site as [ConstructionSite::Void]
+    ///
+    /// # Examples
+    ///
+    /// See [Self].
+    ///
+    /// ```
+    /// use rosenpass_util::build::{ConstructionSite, Build};
+    ///
+    /// #[derive(Debug, Eq, PartialEq, Clone, Copy)]
+    /// struct House;
+    /// #[derive(Debug, Eq, PartialEq, Clone, Copy)]
+    /// struct Builder;
+    ///
+    /// impl Build<House> for Builder {
+    ///     type Error = anyhow::Error;
+    ///
+    ///     fn build(self) -> Result<House, Self::Error> {
+    ///         Ok(House)
+    ///     }
+    /// }
+    ///
+    /// assert_eq!(
+    ///     ConstructionSite::<Builder, House>::void(),
+    ///     ConstructionSite::Void,
+    /// );
+    /// ```
     pub fn void() -> Self {
         Self::Void
     }
 
+    /// Initialize the construction site from its builder
+    ///
+    /// # Examples
+    ///
+    ///
+    /// ```
+    /// use rosenpass_util::build::{ConstructionSite, Build};
+    ///
+    /// #[derive(Debug, Eq, PartialEq, Clone, Copy)]
+    /// struct House;
+    /// #[derive(Debug, Eq, PartialEq, Clone, Copy)]
+    /// struct Builder;
+    ///
+    /// impl Build<House> for Builder {
+    ///     type Error = anyhow::Error;
+    ///
+    ///     fn build(self) -> Result<House, Self::Error> {
+    ///         Ok(House)
+    ///     }
+    /// }
+    ///
+    /// assert_eq!(
+    ///     ConstructionSite::<Builder, House>::new(Builder),
+    ///     ConstructionSite::Builder(Builder),
+    /// );
+    /// ```
     pub fn new(builder: Builder) -> Self {
         Self::Builder(builder)
     }
 
+    /// Initialize the construction site from its product
+    ///
+    /// # Examples
+    ///
+    ///
+    /// ```
+    /// use rosenpass_util::build::{ConstructionSite, Build};
+    ///
+    /// #[derive(Debug, Eq, PartialEq, Clone, Copy)]
+    /// struct House;
+    /// #[derive(Debug, Eq, PartialEq, Clone, Copy)]
+    /// struct Builder;
+    ///
+    /// impl Build<House> for Builder {
+    ///     type Error = anyhow::Error;
+    ///
+    ///     fn build(self) -> Result<House, Self::Error> {
+    ///         Ok(House)
+    ///     }
+    /// }
+    ///
+    /// assert_eq!(
+    ///     ConstructionSite::<Builder, House>::from_product(House),
+    ///     ConstructionSite::Product(House),
+    /// );
+    /// ```
     pub fn from_product(value: T) -> Self {
         Self::Product(value)
     }
 
+    /// Extract the construction site and replace it with [Self::Void]
+    ///
+    /// # Examples
+    ///
+    ///
+    /// ```
+    /// use rosenpass_util::build::{ConstructionSite, Build};
+    ///
+    /// #[derive(Debug, Eq, PartialEq, Clone, Copy)]
+    /// struct House;
+    /// #[derive(Debug, Eq, PartialEq, Clone, Copy)]
+    /// struct Builder;
+    ///
+    /// impl Build<House> for Builder {
+    ///     type Error = anyhow::Error;
+    ///
+    ///     fn build(self) -> Result<House, Self::Error> {
+    ///         Ok(House)
+    ///     }
+    /// }
+    ///
+    /// let mut a = ConstructionSite::<Builder, House>::from_product(House);
+    /// let a_backup = a.clone();
+    ///
+    /// let b = a.take();
+    /// assert_eq!(a, ConstructionSite::void());
+    /// assert_eq!(b, ConstructionSite::Product(House));
+    /// ```
     pub fn take(&mut self) -> Self {
         self.swap_with_default()
     }
 
+    /// Apply the given function to Self, temporarily converting
+    /// the mutable reference into an owned value.
+    ///
+    /// This is useful if you have some function that needs to modify
+    /// the construction site as an owned value but all you have is a reference.
+    ///
+    /// # Examples
+    ///
+    ///
+    /// ```
+    /// use rosenpass_util::build::{ConstructionSite, Build};
+    ///
+    /// #[derive(Debug, Eq, PartialEq, Clone, Copy)]
+    /// struct House(u32);
+    /// #[derive(Debug, Eq, PartialEq, Clone, Copy)]
+    /// struct Builder(u32);
+    ///
+    /// impl Build<House> for Builder {
+    ///     type Error = anyhow::Error;
+    ///
+    ///     fn build(self) -> Result<House, Self::Error> {
+    ///         Ok(House(self.0))
+    ///     }
+    /// }
+    ///
+    /// #[derive(Debug, PartialEq, Eq)]
+    /// enum FancyMatchState {
+    ///     New,
+    ///     Built,
+    ///     Increment,
+    /// };
+    ///
+    /// fn fancy_match(site: &mut ConstructionSite<Builder, House>, def: u32) -> FancyMatchState {
+    ///      site.modify_taken_with_return(|site| {
+    ///          use ConstructionSite as C;
+    ///          use FancyMatchState as F;
+    ///          let (prod, state) = match site {
+    ///              C::Void              => (House(def), F::New),
+    ///              C::Builder(b)        => (b.build().unwrap(), F::Built),
+    ///              C::Product(House(v)) => (House(v + 1), F::Increment),
+    ///          };
+    ///          let prod = ConstructionSite::from_product(prod);
+    ///          (prod, state)
+    ///      })
+    /// }
+    ///
+    /// let mut a = ConstructionSite::void();
+    /// let r = fancy_match(&mut a, 42);
+    /// assert_eq!(a, ConstructionSite::Product(House(42)));
+    /// assert_eq!(r, FancyMatchState::New);
+    ///
+    /// let mut a = ConstructionSite::new(Builder(13));
+    /// let r = fancy_match(&mut a, 42);
+    /// assert_eq!(a, ConstructionSite::Product(House(13)));
+    /// assert_eq!(r, FancyMatchState::Built);
+    ///
+    /// let r = fancy_match(&mut a, 42);
+    /// assert_eq!(a, ConstructionSite::Product(House(14)));
+    /// assert_eq!(r, FancyMatchState::Increment);
+    /// ```
     pub fn modify_taken_with_return<R, F>(&mut self, f: F) -> R
     where
         F: FnOnce(Self) -> (Self, R),
@@ -66,6 +363,53 @@ where
         res
     }
 
+    /// Apply the given function to Self, temporarily converting
+    /// the mutable reference into an owned value.
+    ///
+    /// This is useful if you have some function that needs to modify
+    /// the construction site as an owned value but all you have is a reference.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use rosenpass_util::build::{ConstructionSite, Build};
+    ///
+    /// #[derive(Debug, Eq, PartialEq, Clone, Copy)]
+    /// struct House(u32);
+    /// #[derive(Debug, Eq, PartialEq, Clone, Copy)]
+    /// struct Builder(u32);
+    ///
+    /// impl Build<House> for Builder {
+    ///     type Error = anyhow::Error;
+    ///
+    ///     fn build(self) -> Result<House, Self::Error> {
+    ///         Ok(House(self.0))
+    ///     }
+    /// }
+    ///
+    /// fn fancy_match(site: &mut ConstructionSite<Builder, House>, def: u32) {
+    ///      site.modify_taken(|site| {
+    ///          use ConstructionSite as C;
+    ///          let prod = match site {
+    ///              C::Void              => House(def),
+    ///              C::Builder(b)        => b.build().unwrap(),
+    ///              C::Product(House(v)) => House(v + 1),
+    ///          };
+    ///          ConstructionSite::from_product(prod)
+    ///      })
+    /// }
+    ///
+    /// let mut a = ConstructionSite::void();
+    /// fancy_match(&mut a, 42);
+    /// assert_eq!(a, ConstructionSite::Product(House(42)));
+    ///
+    /// let mut a = ConstructionSite::new(Builder(13));
+    /// fancy_match(&mut a, 42);
+    /// assert_eq!(a, ConstructionSite::Product(House(13)));
+    ///
+    /// fancy_match(&mut a, 42);
+    /// assert_eq!(a, ConstructionSite::Product(House(14)));
+    /// ```
     pub fn modify_taken<F>(&mut self, f: F)
     where
         F: FnOnce(Self) -> Self,
@@ -73,6 +417,42 @@ where
         self.take().apply(f).swap_with_mut(self)
     }
 
+    /// If this constructions site contains [Self::Builder], call the inner [Build]'s [Build::build]
+    /// and have the construction site contain a product.
+    ///
+    /// # Examples
+    ///
+    /// See [Self].
+    ///
+    /// ```
+    /// use rosenpass_util::build::{ConstructionSite, Build, ConstructionSiteErectError};
+    /// use std::convert::Infallible;
+    ///
+    /// #[derive(Debug, Eq, PartialEq, Clone, Copy)]
+    /// struct House;
+    /// #[derive(Debug, Eq, PartialEq, Clone, Copy)]
+    /// struct Builder;
+    ///
+    /// impl Build<House> for Builder {
+    ///     type Error = Infallible;
+    ///
+    ///     fn build(self) -> Result<House, Self::Error> {
+    ///         Ok(House)
+    ///     }
+    /// }
+    ///
+    /// let mut a = ConstructionSite::<Builder, House>::void();
+    /// assert_eq!(a.erect(), Err(ConstructionSiteErectError::IsVoid));
+    /// assert_eq!(a, ConstructionSite::void());
+    ///
+    /// let mut a = ConstructionSite::<Builder, House>::from_product(House);
+    /// assert_eq!(a.erect(), Err(ConstructionSiteErectError::AlreadyBuilt));
+    /// assert_eq!(a, ConstructionSite::from_product(House));
+    ///
+    /// let mut a = ConstructionSite::<Builder, House>::new(Builder);
+    /// a.erect().unwrap();
+    /// assert_eq!(a, ConstructionSite::from_product(House));
+    /// ```
     #[allow(clippy::result_unit_err)]
     pub fn erect(&mut self) -> Result<(), ConstructionSiteErectError<Builder::Error>> {
         self.modify_taken_with_return(|site| {
@@ -98,6 +478,31 @@ where
     /// Returns `true` if the construction site is [`Void`].
     ///
     /// [`Void`]: ConstructionSite::Void
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use rosenpass_util::build::{ConstructionSite, Build};
+    ///
+    /// #[derive(Debug, Eq, PartialEq, Clone, Copy)]
+    /// struct House;
+    /// #[derive(Debug, Eq, PartialEq, Clone, Copy)]
+    /// struct Builder;
+    ///
+    /// impl Build<House> for Builder {
+    ///     type Error = anyhow::Error;
+    ///
+    ///     fn build(self) -> Result<House, Self::Error> {
+    ///         Ok(House)
+    ///     }
+    /// }
+    ///
+    /// type Site = ConstructionSite<Builder, House>;
+    ///
+    /// assert_eq!(Site::Void.is_void(), true);
+    /// assert_eq!(Site::Builder(Builder).is_void(), false);
+    /// assert_eq!(Site::Product(House).is_void(), false);
+    /// ```
     #[must_use]
     pub fn is_void(&self) -> bool {
         matches!(self, Self::Void)
@@ -106,19 +511,95 @@ where
     /// Returns `true` if the construction site is [`InProgress`].
     ///
     /// [`InProgress`]: ConstructionSite::InProgress
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use rosenpass_util::build::{ConstructionSite, Build};
+    ///
+    /// #[derive(Debug, Eq, PartialEq, Clone, Copy)]
+    /// struct House;
+    /// #[derive(Debug, Eq, PartialEq, Clone, Copy)]
+    /// struct Builder;
+    ///
+    /// impl Build<House> for Builder {
+    ///     type Error = anyhow::Error;
+    ///
+    ///     fn build(self) -> Result<House, Self::Error> {
+    ///         Ok(House)
+    ///     }
+    /// }
+    ///
+    /// type Site = ConstructionSite<Builder, House>;
+    ///
+    /// assert_eq!(Site::Void.in_progress(), false);
+    /// assert_eq!(Site::Builder(Builder).in_progress(), true);
+    /// assert_eq!(Site::Product(House).in_progress(), false);
+    /// ```
     #[must_use]
-    pub fn in_progess(&self) -> bool {
+    pub fn in_progress(&self) -> bool {
         matches!(self, Self::Builder(..))
     }
 
     /// Returns `true` if the construction site is [`Done`].
     ///
     /// [`Done`]: ConstructionSite::Done
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use rosenpass_util::build::{ConstructionSite, Build};
+    ///
+    /// #[derive(Debug, Eq, PartialEq, Clone, Copy)]
+    /// struct House;
+    /// #[derive(Debug, Eq, PartialEq, Clone, Copy)]
+    /// struct Builder;
+    ///
+    /// impl Build<House> for Builder {
+    ///     type Error = anyhow::Error;
+    ///
+    ///     fn build(self) -> Result<House, Self::Error> {
+    ///         Ok(House)
+    ///     }
+    /// }
+    ///
+    /// type Site = ConstructionSite<Builder, House>;
+    ///
+    /// assert_eq!(Site::Void.is_available(), false);
+    /// assert_eq!(Site::Builder(Builder).is_available(), false);
+    /// assert_eq!(Site::Product(House).is_available(), true);
+    /// ```
     #[must_use]
     pub fn is_available(&self) -> bool {
         matches!(self, Self::Product(..))
     }
 
+    /// Returns the value of [Self::Builder]
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use rosenpass_util::build::{ConstructionSite, Build};
+    ///
+    /// #[derive(Debug, Eq, PartialEq, Clone, Copy)]
+    /// struct House;
+    /// #[derive(Debug, Eq, PartialEq, Clone, Copy)]
+    /// struct Builder;
+    ///
+    /// impl Build<House> for Builder {
+    ///     type Error = anyhow::Error;
+    ///
+    ///     fn build(self) -> Result<House, Self::Error> {
+    ///         Ok(House)
+    ///     }
+    /// }
+    ///
+    /// type Site = ConstructionSite<Builder, House>;
+    ///
+    /// assert_eq!(Site::Void.into_builder(), None);
+    /// assert_eq!(Site::Builder(Builder).into_builder(), Some(Builder));
+    /// assert_eq!(Site::Product(House).into_builder(), None);
+    /// ```
     pub fn into_builder(self) -> Option<Builder> {
         use ConstructionSite as S;
         match self {
@@ -127,6 +608,11 @@ where
         }
     }
 
+    /// Returns the value of [Self::Builder] as a reference
+    ///
+    /// # Examples
+    ///
+    /// See [Self::into_builder].
     pub fn builder_ref(&self) -> Option<&Builder> {
         use ConstructionSite as S;
         match self {
@@ -135,6 +621,11 @@ where
         }
     }
 
+    /// Returns the value of [Self::Builder] as a mutable reference
+    ///
+    /// # Examples
+    ///
+    /// Similar to [Self::into_builder].
     pub fn builder_mut(&mut self) -> Option<&mut Builder> {
         use ConstructionSite as S;
         match self {
@@ -143,6 +634,11 @@ where
         }
     }
 
+    /// Returns the value of [Self::Product]
+    ///
+    /// # Examples
+    ///
+    /// Similar to [Self::into_builder].
     pub fn into_product(self) -> Option<T> {
         use ConstructionSite as S;
         match self {
@@ -151,6 +647,11 @@ where
         }
     }
 
+    /// Returns the value of [Self::Product] as a reference
+    ///
+    /// # Examples
+    ///
+    /// Similar to [Self::into_builder].
     pub fn product_ref(&self) -> Option<&T> {
         use ConstructionSite as S;
         match self {
@@ -159,6 +660,11 @@ where
         }
     }
 
+    /// Returns the value of [Self::Product] as a mutable reference
+    ///
+    /// # Examples
+    ///
+    /// Similar to [Self::into_builder].
     pub fn product_mut(&mut self) -> Option<&mut T> {
         use ConstructionSite as S;
         match self {

util/src/lib.rs

@@ -1,3 +1,5 @@
+#![warn(missing_docs)]
+#![warn(clippy::missing_docs_in_private_items)]
 #![recursion_limit = "256"]
 
 pub mod b64;