107 lines
2.8 KiB
Rust
107 lines
2.8 KiB
Rust
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//! Validated session identifier newtype.
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//!
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//! [`SessionId`] wraps a `String` that has been checked for path-traversal
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//! characters. Construction via `SessionId::new(str)` validates the input
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//! once; the guarantee is then enforced by the type system for all
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//! downstream use.
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//!
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//! # Validation rules
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//!
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//! - Must not be empty
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//! - Must only contain alphanumeric characters, hyphens, and underscores
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use serde::{Deserialize, Serialize};
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use std::fmt;
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use std::path::Path;
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use std::path::PathBuf;
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/// A validated session identifier.
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///
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/// Guarantees the inner string is non-empty and contains no path-traversal
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/// characters (`/`, `\\`, `..`) or other unsafe delimiters.
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#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq, Hash)]
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pub struct SessionId(String);
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impl SessionId {
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/// Validate and construct a `SessionId`.
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///
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/// Returns `Err(msg)` if the input contains path separators, `..`, or
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/// is empty.
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pub fn new(id: &str) -> Result<Self, String> {
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if id.is_empty() {
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return Err("session id must not be empty".to_string());
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}
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if id.contains('/') || id.contains('\\') || id.contains("..") {
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return Err(format!(
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"session id '{id}' must not contain path separators"
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));
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}
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Ok(SessionId(id.to_string()))
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}
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/// Return the underlying string.
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pub fn as_str(&self) -> &str {
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&self.0
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}
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/// Return the underlying owned string.
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pub fn into_string(self) -> String {
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self.0
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}
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/// Append this session id as a component of `base_dir`, yielding
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/// `base_dir / self.0`.
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///
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/// Safe because the id has been validated to contain no path separators.
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pub fn join_to(&self, base_dir: &Path) -> PathBuf {
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base_dir.join(&self.0)
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}
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}
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impl AsRef<str> for SessionId {
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fn as_ref(&self) -> &str {
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&self.0
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}
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}
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impl fmt::Display for SessionId {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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f.write_str(&self.0)
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}
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}
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impl From<SessionId> for String {
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fn from(sid: SessionId) -> Self {
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sid.0
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}
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn test_valid_uuids() {
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assert!(SessionId::new("550e8400-e29b-41d4-a716-446655440000").is_ok());
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assert!(SessionId::new("my-session_123").is_ok());
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}
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#[test]
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fn test_rejects_path_traversal() {
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assert!(SessionId::new("../etc/passwd").is_err());
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assert!(SessionId::new("foo/../../bar").is_err());
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assert!(SessionId::new("foo\\..\\bar").is_err());
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}
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#[test]
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fn test_rejects_empty() {
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assert!(SessionId::new("").is_err());
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}
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#[test]
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fn test_into_string() {
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let sid = SessionId::new("abc-123").unwrap();
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assert_eq!(sid.into_string(), "abc-123");
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}
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}
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