add bearcap utility

Cargo.lock

@@ -1134,6 +1134,7 @@ dependencies = [
  "pretty_env_logger",
  "serde",
  "serde_json",
+ "serde_test",
  "sqlx",
  "thiserror",
  "tokio",
@@ -1445,6 +1446,15 @@ dependencies = [
  "serde",
 ]
 
+[[package]]
+name = "serde_test"
+version = "1.0.151"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f8f77be7305dac4f250891d2f7444276315f3c288176d35746b6a4ca786dacb3"
+dependencies = [
+ "serde",
+]
+
 [[package]]
 name = "serde_urlencoded"
 version = "0.7.1"

Cargo.toml

@@ -16,6 +16,7 @@ log = "0.4"
 pretty_env_logger = "0.4"
 serde = { version = "1.0", features = [ "derive" ] }
 serde_json = "1.0"
+serde_test = "1.0"
 sqlx = { version = "0.6", features = [ "chrono", "runtime-actix-rustls", "postgres" ] }
 thiserror = "1.0"
 tokio = "1.23"

src/core/mod.rs

@@ -8,6 +8,7 @@ use std::{fmt, io};
 
 use crate::util::validate;
 pub use log::{debug, error, info, trace, warn};
+use serde::ser::SerializeMap;
 
 pub use crate::util::validate::{Insane, Sane};
 
@@ -24,6 +25,7 @@ pub enum Error {
     MalformedHeader(header::ToStrError),
     BadToken(jsonwebtoken::errors::Error),
     BadCredentials,
+    BadBearcap,
 }
 
 pub fn utc_now() -> NaiveDateTime {
@@ -33,9 +35,7 @@ pub fn utc_now() -> NaiveDateTime {
 pub fn unix_now() -> i64 {
     SystemTime::now()
         .duration_since(UNIX_EPOCH)
-        .expect(
-            "You've either broken spacetime, or your system clock is a bit off.",
-        )
+        .expect("You've either broken spacetime, or your system clock is a bit off.")
         .as_secs() as i64
 }
 
@@ -47,6 +47,7 @@ impl ResponseError for Error {
             Error::MalformedHeader(_) => StatusCode::BAD_REQUEST,
             Error::BadToken(_) => StatusCode::UNAUTHORIZED,
             Error::BadCredentials => StatusCode::UNAUTHORIZED,
+            Error::BadBearcap => StatusCode::UNPROCESSABLE_ENTITY,
             _ => StatusCode::INTERNAL_SERVER_ERROR,
         }
     }
@@ -66,6 +67,7 @@ impl fmt::Display for Error {
             Error::MalformedHeader(to_str_error) => to_str_error.fmt(f),
             Error::BadToken(jwt_error) => jwt_error.fmt(f),
             Error::BadCredentials => write!(f, "Invalid user name or password"),
+            Error::BadBearcap => write!(f, "Invalid bearcap URL"),
         }
     }
 }
@@ -108,6 +110,8 @@ impl Serialize for Error {
     where
         S: Serializer,
     {
-        serializer.serialize_str(format!("{}", self).as_str())
+        let mut fields = serializer.serialize_map(Some(1))?;
+        fields.serialize_entry("msg", format!("{}", self).as_str())?;
+        fields.end()
     }
 }

src/util/bear.rs

@@ -0,0 +1,185 @@
+use serde::{de, Deserialize, Deserializer, Serialize, Serializer};
+use std::fmt;
+use std::iter::Peekable;
+use std::str::Chars;
+
+use crate::core::*;
+
+const MAX_PARAM_LEN: usize = 16384;
+
+/// Bearer Capabilities URI, see <https://docs.joinmastodon.org/spec/bearcaps/>
+#[derive(PartialEq, Debug)]
+pub struct Bearcap {
+    pub url: String,
+    pub token: String,
+}
+
+struct MaybeBearcap {
+    url: Option<String>,
+    token: Option<String>,
+}
+
+impl TryFrom<&str> for Bearcap {
+    type Error = Error;
+
+    fn try_from(v: &str) -> Result<Self> {
+        const BEAR_PREFIX: &'static str = "bear:";
+        if !v.starts_with(BEAR_PREFIX) {
+            return Err(Error::BadBearcap);
+        }
+        let v = &v[BEAR_PREFIX.len()..];
+
+        let mut params = MaybeBearcap {
+            url: None,
+            token: None,
+        };
+        let mut chars = v.chars().peekable();
+        for _ in 0..2 {
+            match chars.next() {
+                Some('?' | '&') => parse_param(&mut params, &mut chars)?,
+                None => break,
+                _ => return Err(Error::BadBearcap),
+            }
+        }
+
+        params.try_into()
+    }
+}
+
+fn parse_param(params: &mut MaybeBearcap, chars: &mut Peekable<Chars>) -> Result<()> {
+    match chars.next() {
+        Some('t') => params.token = Some(parse_param_val(chars)?),
+        Some('u') => params.url = Some(parse_param_val(chars)?),
+        _ => return Err(Error::BadBearcap),
+    }
+
+    Ok(())
+}
+
+fn parse_param_val(chars: &mut Peekable<Chars>) -> Result<String> {
+    if chars.next() != Some('=') {
+        return Err(Error::BadBearcap);
+    }
+    let mut val = String::new();
+
+    for _ in 0..MAX_PARAM_LEN {
+        let c = chars.peek().map(|c| *c);
+        match c {
+            Some('&') | None => return Ok(val),
+            Some(c) => {
+                chars.next();
+                val.push(c);
+            }
+        }
+    }
+
+    warn!(
+        "Rejecting bearcap with param longer than {} chars",
+        MAX_PARAM_LEN
+    );
+    Err(Error::BadBearcap)
+}
+
+impl TryFrom<MaybeBearcap> for Bearcap {
+    type Error = Error;
+
+    fn try_from(v: MaybeBearcap) -> Result<Self> {
+        if let (Some(token), Some(url)) = (v.token, v.url) {
+            if token.len() > 0 && url.len() > 0 {
+                return Ok(Bearcap { token, url });
+            }
+        }
+
+        Err(Error::BadBearcap)
+    }
+}
+
+impl Serialize for Bearcap {
+    fn serialize<S>(&self, serializer: S) -> std::result::Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        let s = format!("bear:?t={}&u={}", self.token, self.url);
+        serializer.serialize_str(s.as_str())
+    }
+}
+
+impl<'de> Deserialize<'de> for Bearcap {
+    fn deserialize<D>(deserializer: D) -> std::result::Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        deserializer.deserialize_str(BearcapVisitor)
+    }
+}
+
+struct BearcapVisitor;
+
+impl<'de> de::Visitor<'de> for BearcapVisitor {
+    type Value = Bearcap;
+
+    fn expecting(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.write_str("a valid bearcap URI")
+    }
+
+    fn visit_str<E>(self, value: &str) -> std::result::Result<Self::Value, E>
+    where
+        E: de::Error,
+    {
+        match Bearcap::try_from(value) {
+            Ok(bc) => Ok(bc),
+            Err(_) => Err(E::custom("Expected a valid bearcap URI")),
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::util::bear::Bearcap;
+    use serde_test::{assert_tokens, Token};
+
+    #[test]
+    fn parse_vali() {
+        let bc = Bearcap::try_from("bear:?t=asdf&u=https://example.com/test")
+            .expect("Doesn't parse valid bearcap");
+        assert_eq!(bc.url, String::from("https://example.com/test"));
+        assert_eq!(bc.token, String::from("asdf"));
+    }
+
+    #[test]
+    fn serialize() {
+        let bc = Bearcap {
+            token: String::from("asdf"),
+            url: String::from("https://example.com/test"),
+        };
+
+        assert_tokens(
+            &bc,
+            &[Token::Str("bear:?t=asdf&u=https://example.com/test")],
+        );
+    }
+
+    #[test]
+    fn reject_without_url() {
+        let result = Bearcap::try_from("bear:?t=asdf");
+        assert!(result.is_err());
+    }
+
+    #[test]
+    fn reject_without_token() {
+        let result = Bearcap::try_from("bear:?u=https://example.com/test");
+        assert!(result.is_err());
+    }
+
+    #[test]
+    fn reject_with_empty_token() {
+        let result = Bearcap::try_from("bear:?t=&u=https://example.com/test");
+        assert!(result.is_err());
+    }
+
+    #[test]
+    fn reject_with_empty_url() {
+        let result = Bearcap::try_from("bear:?t=asdf&u=");
+        assert!(result.is_err());
+    }
+}

src/util/mod.rs

@@ -1,3 +1,4 @@
+pub mod bear;
 pub mod password;
 pub mod token;
 pub mod validate;