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|
use anyhow::{Result, anyhow};
use base64::{Engine, engine::general_purpose::URL_SAFE_NO_PAD};
use sha2::{Digest, Sha256};
#[derive(Debug, Clone, PartialEq)]
pub enum CodeChallengeMethod {
Plain,
S256,
}
impl CodeChallengeMethod {
pub fn from_str(s: &str) -> Result<Self> {
match s {
"plain" => Ok(CodeChallengeMethod::Plain),
"S256" => Ok(CodeChallengeMethod::S256),
_ => Err(anyhow!("Unsupported code challenge method: {}", s)),
}
}
pub fn as_str(&self) -> &'static str {
match self {
CodeChallengeMethod::Plain => "plain",
CodeChallengeMethod::S256 => "S256",
}
}
}
pub fn verify_code_challenge(
code_verifier: &str,
code_challenge: &str,
method: &CodeChallengeMethod,
) -> Result<bool> {
// Validate code verifier format (RFC 7636 Section 4.1)
if code_verifier.len() < 43 || code_verifier.len() > 128 {
return Err(anyhow!(
"Code verifier length must be between 43 and 128 characters"
));
}
// Code verifier must only contain unreserved characters
if !code_verifier
.chars()
.all(|c| c.is_ascii_alphanumeric() || c == '-' || c == '.' || c == '_' || c == '~')
{
return Err(anyhow!("Code verifier contains invalid characters"));
}
let computed_challenge = match method {
CodeChallengeMethod::Plain => code_verifier.to_string(),
CodeChallengeMethod::S256 => {
let mut hasher = Sha256::new();
hasher.update(code_verifier.as_bytes());
URL_SAFE_NO_PAD.encode(hasher.finalize())
}
};
Ok(computed_challenge == code_challenge)
}
pub fn generate_code_verifier() -> String {
use rand::Rng;
let mut rng = rand::thread_rng();
// Generate 32 random bytes and encode them
let bytes: Vec<u8> = (0..32).map(|_| rng.r#gen()).collect();
URL_SAFE_NO_PAD.encode(&bytes)
}
pub fn generate_code_challenge(verifier: &str, method: &CodeChallengeMethod) -> String {
match method {
CodeChallengeMethod::Plain => verifier.to_string(),
CodeChallengeMethod::S256 => {
let mut hasher = Sha256::new();
hasher.update(verifier.as_bytes());
URL_SAFE_NO_PAD.encode(hasher.finalize())
}
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_code_challenge_method_from_str() {
assert_eq!(
CodeChallengeMethod::from_str("plain").unwrap(),
CodeChallengeMethod::Plain
);
assert_eq!(
CodeChallengeMethod::from_str("S256").unwrap(),
CodeChallengeMethod::S256
);
assert!(CodeChallengeMethod::from_str("invalid").is_err());
}
#[test]
fn test_code_challenge_method_as_str() {
assert_eq!(CodeChallengeMethod::Plain.as_str(), "plain");
assert_eq!(CodeChallengeMethod::S256.as_str(), "S256");
}
#[test]
fn test_verify_code_challenge_plain() {
let verifier = "dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk";
let challenge = "dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk";
assert!(verify_code_challenge(verifier, challenge, &CodeChallengeMethod::Plain).unwrap());
assert!(!verify_code_challenge(verifier, "wrong", &CodeChallengeMethod::Plain).unwrap());
}
#[test]
fn test_verify_code_challenge_s256() {
let verifier = "dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk";
let challenge = "E9Melhoa2OwvFrEMTJguCHaoeK1t8URWbuGJSstw-cM";
assert!(verify_code_challenge(verifier, challenge, &CodeChallengeMethod::S256).unwrap());
assert!(!verify_code_challenge(verifier, "wrong", &CodeChallengeMethod::S256).unwrap());
}
#[test]
fn test_verify_code_challenge_invalid_verifier() {
// Too short
assert!(verify_code_challenge("short", "challenge", &CodeChallengeMethod::Plain).is_err());
// Invalid characters
assert!(
verify_code_challenge(
"dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjX!",
"challenge",
&CodeChallengeMethod::Plain
)
.is_err()
);
}
#[test]
fn test_generate_code_verifier() {
let verifier = generate_code_verifier();
assert!(verifier.len() >= 43);
assert!(verifier.len() <= 128);
// Should only contain valid characters
assert!(verifier.chars().all(|c| {
c.is_ascii_alphanumeric() || c == '-' || c == '.' || c == '_' || c == '~'
}));
}
#[test]
fn test_generate_code_challenge() {
let verifier = "dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk";
let plain_challenge = generate_code_challenge(verifier, &CodeChallengeMethod::Plain);
assert_eq!(plain_challenge, verifier);
let s256_challenge = generate_code_challenge(verifier, &CodeChallengeMethod::S256);
assert_eq!(
s256_challenge,
"E9Melhoa2OwvFrEMTJguCHaoeK1t8URWbuGJSstw-cM"
);
}
#[test]
fn test_round_trip() {
let verifier = generate_code_verifier();
// Test with S256
let challenge = generate_code_challenge(&verifier, &CodeChallengeMethod::S256);
assert!(verify_code_challenge(&verifier, &challenge, &CodeChallengeMethod::S256).unwrap());
// Test with Plain
let challenge = generate_code_challenge(&verifier, &CodeChallengeMethod::Plain);
assert!(verify_code_challenge(&verifier, &challenge, &CodeChallengeMethod::Plain).unwrap());
}
}
|
