Axum migration: CSRF token and login page

crates/axum-utils/src/csrf.rs

@@ -19,7 +19,7 @@ use serde::{Deserialize, Serialize};
 use serde_with::{serde_as, TimestampSeconds};
 use thiserror::Error;
 
-use crate::{CookieExt, PrivateCookieJar};
+use crate::{cookies::CookieDecodeError, CookieExt, PrivateCookieJar};
 
 /// Failed to validate CSRF token
 #[derive(Debug, Error)]
@@ -28,6 +28,14 @@ pub enum CsrfError {
     #[error("CSRF token mismatch")]
     Mismatch,
 
+    /// The token in the form did not match the token in the cookie
+    #[error("Missing CSRF cookie")]
+    Missing,
+
+    /// Failed to decode the token
+    #[error("could not decode CSRF cookie")]
+    DecodeCookie(#[from] CookieDecodeError),
+
     /// The token expired
     #[error("CSRF token expired")]
     Expired,
@@ -89,8 +97,18 @@ impl CsrfToken {
     }
 }
 
+// A CSRF-protected form
+#[derive(Deserialize)]
+pub struct ProtectedForm<T> {
+    csrf: String,
+
+    #[serde(flatten)]
+    inner: T,
+}
+
 pub trait CsrfExt {
     fn csrf_token(self) -> (CsrfToken, Self);
+    fn verify_form<T>(&self, form: ProtectedForm<T>) -> Result<T, CsrfError>;
 }
 
 impl<K> CsrfExt for PrivateCookieJar<K> {
@@ -108,4 +126,12 @@ impl<K> CsrfExt for PrivateCookieJar<K> {
         let jar = jar.add(cookie);
         (new_token, jar)
     }
+
+    fn verify_form<T>(&self, form: ProtectedForm<T>) -> Result<T, CsrfError> {
+        let cookie = self.get("csrf").ok_or(CsrfError::Missing)?;
+        let token: CsrfToken = cookie.decode()?;
+        let token = token.verify_expiration()?;
+        token.verify_form_value(&form.csrf)?;
+        Ok(form.inner)
+    }
 }

crates/axum-utils/src/fancy_error.rs

@@ -50,7 +50,9 @@ where
     }
 }
 
-pub fn fancy_error<E: Error + 'static>(templates: Templates) -> impl Fn(E) -> FancyError {
+pub fn fancy_error<E: std::fmt::Display + 'static>(
+    templates: Templates,
+) -> impl Fn(E) -> FancyError {
     move |error: E| FancyError {
         templates: Some(templates.clone()),
         error: Box::new(error),
@@ -69,7 +71,7 @@ where
 
 pub struct FancyError {
     templates: Option<Templates>,
-    error: Box<dyn Error>,
+    error: Box<dyn std::fmt::Display>,
 }
 
 impl IntoResponse for FancyError {
@@ -99,4 +101,3 @@ impl IntoResponse for FancyError {
         res
     }
 }
-