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lewis.moe
1use base64::Engine;
2use base64::engine::general_purpose::URL_SAFE_NO_PAD;
3use chrono::Utc;
4use hmac::Mac;
5use sha2::{Digest, Sha256};
6use subtle::ConstantTimeEq;
7use crate::config::AuthConfig;
8use crate::oauth::OAuthError;
9
10const ACCESS_TOKEN_EXPIRY_SECONDS: i64 = 3600;
11
12pub struct TokenClaims {
13 pub jti: String,
14 pub exp: i64,
15 pub iat: i64,
16}
17
18pub fn verify_pkce(code_challenge: &str, code_verifier: &str) -> Result<(), OAuthError> {
19 let mut hasher = Sha256::new();
20 hasher.update(code_verifier.as_bytes());
21 let hash = hasher.finalize();
22 let computed_challenge = URL_SAFE_NO_PAD.encode(&hash);
23 if !bool::from(computed_challenge.as_bytes().ct_eq(code_challenge.as_bytes())) {
24 return Err(OAuthError::InvalidGrant("PKCE verification failed".to_string()));
25 }
26 Ok(())
27}
28
29pub fn create_access_token(
30 token_id: &str,
31 sub: &str,
32 dpop_jkt: Option<&str>,
33) -> Result<String, OAuthError> {
34 use serde_json::json;
35 let pds_hostname = std::env::var("PDS_HOSTNAME").unwrap_or_else(|_| "localhost".to_string());
36 let issuer = format!("https://{}", pds_hostname);
37 let now = Utc::now().timestamp();
38 let exp = now + ACCESS_TOKEN_EXPIRY_SECONDS;
39 let mut payload = json!({
40 "iss": issuer,
41 "sub": sub,
42 "aud": issuer,
43 "iat": now,
44 "exp": exp,
45 "jti": token_id,
46 "scope": "atproto"
47 });
48 if let Some(jkt) = dpop_jkt {
49 payload["cnf"] = json!({ "jkt": jkt });
50 }
51 let header = json!({
52 "alg": "HS256",
53 "typ": "at+jwt"
54 });
55 let header_b64 = URL_SAFE_NO_PAD.encode(serde_json::to_string(&header).unwrap());
56 let payload_b64 = URL_SAFE_NO_PAD.encode(serde_json::to_string(&payload).unwrap());
57 let signing_input = format!("{}.{}", header_b64, payload_b64);
58 let config = AuthConfig::get();
59 type HmacSha256 = hmac::Hmac<Sha256>;
60 let mut mac = HmacSha256::new_from_slice(config.jwt_secret().as_bytes())
61 .map_err(|_| OAuthError::ServerError("HMAC key error".to_string()))?;
62 mac.update(signing_input.as_bytes());
63 let signature = mac.finalize().into_bytes();
64 let signature_b64 = URL_SAFE_NO_PAD.encode(&signature);
65 Ok(format!("{}.{}", signing_input, signature_b64))
66}
67
68pub fn extract_token_claims(token: &str) -> Result<TokenClaims, OAuthError> {
69 let parts: Vec<&str> = token.split('.').collect();
70 if parts.len() != 3 {
71 return Err(OAuthError::InvalidToken("Invalid token format".to_string()));
72 }
73 let header_bytes = URL_SAFE_NO_PAD
74 .decode(parts[0])
75 .map_err(|_| OAuthError::InvalidToken("Invalid token encoding".to_string()))?;
76 let header: serde_json::Value = serde_json::from_slice(&header_bytes)
77 .map_err(|_| OAuthError::InvalidToken("Invalid token header".to_string()))?;
78 if header.get("typ").and_then(|t| t.as_str()) != Some("at+jwt") {
79 return Err(OAuthError::InvalidToken("Not an OAuth access token".to_string()));
80 }
81 if header.get("alg").and_then(|a| a.as_str()) != Some("HS256") {
82 return Err(OAuthError::InvalidToken("Unsupported algorithm".to_string()));
83 }
84 let config = AuthConfig::get();
85 let secret = config.jwt_secret();
86 let signing_input = format!("{}.{}", parts[0], parts[1]);
87 let provided_sig = URL_SAFE_NO_PAD
88 .decode(parts[2])
89 .map_err(|_| OAuthError::InvalidToken("Invalid signature encoding".to_string()))?;
90 type HmacSha256 = hmac::Hmac<Sha256>;
91 let mut mac = HmacSha256::new_from_slice(secret.as_bytes())
92 .map_err(|_| OAuthError::ServerError("HMAC initialization failed".to_string()))?;
93 mac.update(signing_input.as_bytes());
94 let expected_sig = mac.finalize().into_bytes();
95 if !bool::from(expected_sig.ct_eq(&provided_sig)) {
96 return Err(OAuthError::InvalidToken("Invalid token signature".to_string()));
97 }
98 let payload_bytes = URL_SAFE_NO_PAD
99 .decode(parts[1])
100 .map_err(|_| OAuthError::InvalidToken("Invalid payload encoding".to_string()))?;
101 let payload: serde_json::Value = serde_json::from_slice(&payload_bytes)
102 .map_err(|_| OAuthError::InvalidToken("Invalid token payload".to_string()))?;
103 let jti = payload
104 .get("jti")
105 .and_then(|j| j.as_str())
106 .ok_or_else(|| OAuthError::InvalidToken("Missing jti claim".to_string()))?
107 .to_string();
108 let exp = payload
109 .get("exp")
110 .and_then(|e| e.as_i64())
111 .ok_or_else(|| OAuthError::InvalidToken("Missing exp claim".to_string()))?;
112 let iat = payload
113 .get("iat")
114 .and_then(|i| i.as_i64())
115 .ok_or_else(|| OAuthError::InvalidToken("Missing iat claim".to_string()))?;
116 Ok(TokenClaims { jti, exp, iat })
117}