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use std::str::FromStr;
use std::path::PathBuf;
use crate::error::Empty;
use crate::http::uri::{Segments, error::PathError, fmt::Path};
/// Trait to convert a dynamic path segment string to a concrete value.
///
/// This trait is used by Rocket's code generation facilities to parse dynamic
/// path segment string values into a given type. That is, when a path contains
/// a dynamic segment `<param>` where `param` has some type `T` that implements
/// `FromParam`, `T::from_param` will be called.
///
/// # Forwarding
///
/// If the conversion fails, the incoming request will be forwarded to the next
/// matching route, if any. For instance, consider the following route and
/// handler for the dynamic `"/<id>"` path:
///
/// ```rust
/// # #[macro_use] extern crate rocket;
/// #[get("/<id>")]
/// fn hello(id: usize) -> String {
/// # let _id = id;
/// # /*
/// ...
/// # */
/// # "".to_string()
/// }
/// # fn main() { }
/// ```
///
/// If `usize::from_param` returns an `Ok(usize)` variant, the encapsulated
/// value is used as the `id` function parameter. If not, the request is
/// forwarded to the next matching route. Since there are no additional matching
/// routes, this example will result in a 404 error for requests with invalid
/// `id` values.
///
/// # Catching Errors
///
/// Sometimes, a forward is not desired, and instead, we simply want to know
/// that the dynamic path segment could not be parsed into some desired type
/// `T`. In these cases, types of `Option<T>` or `Result<T, T::Error>` can be
/// used. These types implement `FromParam` themselves. Their implementations
/// always return successfully, so they never forward. They can be used to
/// determine if the `FromParam` call failed and to retrieve the error value
/// from the failed `from_param` call.
///
/// For instance, imagine you've asked for an `<id>` as a `usize`. To determine
/// when the `<id>` was not a valid `usize` and retrieve the string that failed
/// to parse, you can use a `Result<usize, &str>` type for the `<id>` parameter
/// as follows:
///
/// ```rust
/// # #[macro_use] extern crate rocket;
/// #[get("/<id>")]
/// fn hello(id: Result<usize, &str>) -> String {
/// match id {
/// Ok(id_num) => format!("usize: {}", id_num),
/// Err(string) => format!("Not a usize: {}", string)
/// }
/// }
/// # fn main() { }
/// ```
///
/// # Provided Implementations
///
/// Rocket implements `FromParam` for several standard library types. Their
/// behavior is documented here.
///
/// *
/// * Primitive types: **f32, f64, isize, i8, i16, i32, i64, i128,
/// usize, u8, u16, u32, u64, u128, bool**
/// * `IpAddr` and `SocketAddr` types: **IpAddr, Ipv4Addr, Ipv6Addr,
/// SocketAddrV4, SocketAddrV6, SocketAddr**
/// * `NonZero*` types: **NonZeroI8, NonZeroI16, NonZeroI32, NonZeroI64,
/// NonZeroI128, NonZeroIsize, NonZeroU8, NonZeroU16, NonZeroU32,
/// NonZeroU64, NonZeroU128, NonZeroUsize**
///
/// A value is parsed successfully if the `from_str` method from the given
/// type returns successfully. Otherwise, the raw path segment is returned
/// in the `Err` value.
///
/// * **&str, String**
///
/// _This implementation always returns successfully._
///
/// Returns the percent-decoded path segment with invalid UTF-8 byte
/// sequences replaced by � U+FFFD.
///
/// * **Option<T>** _where_ **T: FromParam**
///
/// _This implementation always returns successfully._
///
/// The path segment is parsed by `T`'s `FromParam` implementation. If the
/// parse succeeds, a `Some(parsed_value)` is returned. Otherwise, a `None`
/// is returned.
///
/// * **Result<T, T::Error>** _where_ **T: FromParam**
///
/// _This implementation always returns successfully._
///
/// The path segment is parsed by `T`'s `FromParam` implementation. The
/// returned `Result` value is returned.
///
/// # Example
///
/// Say you want to parse a segment of the form:
///
/// ```text
/// [a-zA-Z]+:[0-9]+
/// ```
///
/// into the following structure, where the string before the `:` is stored in
/// `key` and the number after the colon is stored in `value`:
///
/// ```rust
/// struct MyParam<'r> {
/// key: &'r str,
/// value: usize
/// }
/// ```
///
/// The following implementation accomplishes this:
///
/// ```rust
/// use rocket::request::FromParam;
/// # #[allow(dead_code)]
/// # struct MyParam<'r> { key: &'r str, value: usize }
///
/// impl<'r> FromParam<'r> for MyParam<'r> {
/// type Error = &'r str;
///
/// fn from_param(param: &'r str) -> Result<Self, Self::Error> {
/// // We can convert `param` into a `str` since we'll check every
/// // character for safety later.
/// let (key, val_str) = match param.find(':') {
/// Some(i) if i > 0 => (¶m[..i], ¶m[(i + 1)..]),
/// _ => return Err(param)
/// };
///
/// if !key.chars().all(|c| c.is_ascii_alphabetic()) {
/// return Err(param);
/// }
///
/// val_str.parse()
/// .map(|value| MyParam { key, value })
/// .map_err(|_| param)
/// }
/// }
/// ```
///
/// With the implementation, the `MyParam` type can be used as the target of a
/// dynamic path segment:
///
/// ```rust
/// # #[macro_use] extern crate rocket;
/// # use rocket::request::FromParam;
/// # #[allow(dead_code)]
/// # struct MyParam<'r> { key: &'r str, value: usize }
/// # impl<'r> FromParam<'r> for MyParam<'r> {
/// # type Error = &'r str;
/// # fn from_param(param: &'r str) -> Result<Self, Self::Error> {
/// # Err(param)
/// # }
/// # }
/// #
/// #[get("/<key_val>")]
/// fn hello(key_val: MyParam) -> String {
/// # let _kv = key_val;
/// # /*
/// ...
/// # */
/// # "".to_string()
/// }
/// # fn main() { }
/// ```
pub trait FromParam<'a>: Sized {
/// The associated error to be returned if parsing/validation fails.
type Error: std::fmt::Debug;
/// Parses and validates an instance of `Self` from a path parameter string
/// or returns an `Error` if parsing or validation fails.
fn from_param(param: &'a str) -> Result<Self, Self::Error>;
}
impl<'a> FromParam<'a> for &'a str {
type Error = Empty;
#[inline(always)]
fn from_param(param: &'a str) -> Result<&'a str, Self::Error> {
if param.is_empty() {
return Err(Empty);
}
Ok(param)
}
}
impl<'a> FromParam<'a> for String {
type Error = Empty;
#[track_caller]
#[inline(always)]
fn from_param(param: &'a str) -> Result<String, Self::Error> {
#[cfg(debug_assertions)] {
let loc = std::panic::Location::caller();
warn_!("Note: Using `String` as a parameter type is inefficient. Use `&str` instead.");
info_!("`String` is used a parameter guard in {}:{}.", loc.file(), loc.line());
}
if param.is_empty() {
return Err(Empty);
}
Ok(param.to_string())
}
}
macro_rules! impl_with_fromstr {
($($T:ty),+) => ($(
impl<'a> FromParam<'a> for $T {
type Error = &'a str;
#[inline(always)]
fn from_param(param: &'a str) -> Result<Self, Self::Error> {
<$T as FromStr>::from_str(param).map_err(|_| param)
}
}
)+)
}
use std::num::{
NonZeroI8, NonZeroI16, NonZeroI32, NonZeroI64, NonZeroI128, NonZeroIsize,
NonZeroU8, NonZeroU16, NonZeroU32, NonZeroU64, NonZeroU128, NonZeroUsize,
};
use std::net::{IpAddr, Ipv4Addr, Ipv6Addr, SocketAddrV4, SocketAddrV6, SocketAddr};
impl_with_fromstr! {
i8, i16, i32, i64, i128, isize, u8, u16, u32, u64, u128, usize, f32, f64,
NonZeroI8, NonZeroI16, NonZeroI32, NonZeroI64, NonZeroI128, NonZeroIsize,
NonZeroU8, NonZeroU16, NonZeroU32, NonZeroU64, NonZeroU128, NonZeroUsize,
bool, IpAddr, Ipv4Addr, Ipv6Addr, SocketAddrV4, SocketAddrV6, SocketAddr
}
impl<'a> FromParam<'a> for PathBuf {
type Error = PathError;
#[inline]
fn from_param(param: &'a str) -> Result<Self, Self::Error> {
use crate::http::private::Indexed;
let segments = &[Indexed::Indexed(0, param.len())];
Segments::new(param.into(), segments).to_path_buf(false)
}
}
impl<'a, T: FromParam<'a>> FromParam<'a> for Result<T, T::Error> {
type Error = std::convert::Infallible;
#[inline]
fn from_param(param: &'a str) -> Result<Self, Self::Error> {
match T::from_param(param) {
Ok(val) => Ok(Ok(val)),
Err(e) => Ok(Err(e)),
}
}
}
impl<'a, T: FromParam<'a>> FromParam<'a> for Option<T> {
type Error = std::convert::Infallible;
#[inline]
fn from_param(param: &'a str) -> Result<Self, Self::Error> {
match T::from_param(param) {
Ok(val) => Ok(Some(val)),
Err(_) => Ok(None)
}
}
}
/// Trait to convert _many_ dynamic path segment strings to a concrete value.
///
/// This is the `..` analog to [`FromParam`], and its functionality is identical
/// to it with one exception: this trait applies to segment parameters of the
/// form `<param..>`, where `param` is of some type `T` that implements
/// `FromSegments`. `T::from_segments` is called to convert the matched segments
/// (via the [`Segments`] iterator) into the implementing type.
///
/// # Provided Implementations
///
/// **`PathBuf`**
///
/// The `PathBuf` implementation constructs a path from the segments iterator.
/// Each segment is percent-decoded. If a segment equals ".." before or after
/// decoding, the previous segment (if any) is omitted. For security purposes,
/// any other segments that begin with "*" or "." are ignored. If a
/// percent-decoded segment results in invalid UTF8, an `Err` is returned with
/// the `Utf8Error`.
pub trait FromSegments<'r>: Sized {
/// The associated error to be returned when parsing fails.
type Error: std::fmt::Debug;
/// Parses an instance of `Self` from many dynamic path parameter strings or
/// returns an `Error` if one cannot be parsed.
fn from_segments(segments: Segments<'r, Path>) -> Result<Self, Self::Error>;
}
impl<'r> FromSegments<'r> for Segments<'r, Path> {
type Error = std::convert::Infallible;
#[inline(always)]
fn from_segments(segments: Self) -> Result<Self, Self::Error> {
Ok(segments)
}
}
/// Creates a `PathBuf` from a `Segments` iterator. The returned `PathBuf` is
/// percent-decoded. If a segment is equal to "..", the previous segment (if
/// any) is skipped.
///
/// For security purposes, if a segment meets any of the following conditions,
/// an `Err` is returned indicating the condition met:
///
/// * Decoded segment starts with any of: `.` (except `..`), `*`
/// * Decoded segment ends with any of: `:`, `>`, `<`
/// * Decoded segment contains any of: `/`
/// * On Windows, decoded segment contains any of: `\`
/// * Percent-encoding results in invalid UTF8.
///
/// As a result of these conditions, a `PathBuf` derived via `FromSegments` is
/// safe to interpolate within, or use as a suffix of, a path without additional
/// checks.
impl FromSegments<'_> for PathBuf {
type Error = PathError;
fn from_segments(segments: Segments<'_, Path>) -> Result<Self, Self::Error> {
segments.to_path_buf(false)
}
}
impl<'r, T: FromSegments<'r>> FromSegments<'r> for Result<T, T::Error> {
type Error = std::convert::Infallible;
#[inline]
fn from_segments(segments: Segments<'r, Path>) -> Result<Result<T, T::Error>, Self::Error> {
match T::from_segments(segments) {
Ok(val) => Ok(Ok(val)),
Err(e) => Ok(Err(e)),
}
}
}
impl<'r, T: FromSegments<'r>> FromSegments<'r> for Option<T> {
type Error = std::convert::Infallible;
#[inline]
fn from_segments(segments: Segments<'r, Path>) -> Result<Option<T>, Self::Error> {
match T::from_segments(segments) {
Ok(val) => Ok(Some(val)),
Err(_) => Ok(None)
}
}
}