refactor: extract TDX quote report_data offset as a named constant

Replace the duplicated magic offset `568..632` with a named constant
`TDX_QUOTE_REPORT_DATA_RANGE` and add a warning log when the quote is
too short to patch report_data, which would indicate data corruption.

Follow-up to PR #541.

Author: kvinwang

dstack-attest/Cargo.toml

@@ -26,6 +26,7 @@ serde_json.workspace = true
 sha2.workspace = true
 sha3.workspace = true
 tdx-attest.workspace = true
+tracing.workspace = true
 insta.workspace = true
 errify.workspace = true
 

dstack-attest/src/attestation.rs

@@ -4,6 +4,11 @@
 
 //! Attestation functions
 
+/// Byte range of the REPORT_DATA field within a TDX quote.
+/// In Intel TDX ECDSA quote format, the TD Report body starts at offset 568
+/// and REPORT_DATA occupies bytes 568..632 (64 bytes).
+pub const TDX_QUOTE_REPORT_DATA_RANGE: std::ops::Range<usize> = 568..632;
+
 use std::{borrow::Cow, time::SystemTime};
 
 use anyhow::{anyhow, bail, Context, Result};
@@ -274,8 +279,14 @@ impl VersionedAttestation {
         let VersionedAttestation::V0 { attestation } = self;
         attestation.report_data = report_data;
         if let Some(tdx_quote) = attestation.tdx_quote_mut() {
-            if tdx_quote.quote.len() >= 632 {
-                tdx_quote.quote[568..632].copy_from_slice(&report_data);
+            if tdx_quote.quote.len() >= TDX_QUOTE_REPORT_DATA_RANGE.end {
+                tdx_quote.quote[TDX_QUOTE_REPORT_DATA_RANGE].copy_from_slice(&report_data);
+            } else {
+                tracing::warn!(
+                    "TDX quote too short to patch report_data ({} < {})",
+                    tdx_quote.quote.len(),
+                    TDX_QUOTE_REPORT_DATA_RANGE.end
+                );
             }
         }
     }

guest-agent/src/rpc_service.rs

@@ -28,7 +28,10 @@ use k256::ecdsa::SigningKey;
 use or_panic::ResultOrPanic;
 use ra_rpc::{Attestation, CallContext, RpcCall};
 use ra_tls::{
-    attestation::{QuoteContentType, VersionedAttestation, DEFAULT_HASH_ALGORITHM},
+    attestation::{
+        QuoteContentType, VersionedAttestation, DEFAULT_HASH_ALGORITHM,
+        TDX_QUOTE_REPORT_DATA_RANGE,
+    },
     cert::CertConfigV2,
     kdf::{derive_key, derive_p256_key_pair_from_bytes},
 };
@@ -486,7 +489,7 @@ fn simulate_quote(
         return Err(anyhow::anyhow!("Quote not found"));
     };
 
-    quote.quote[568..632].copy_from_slice(&report_data);
+    quote.quote[TDX_QUOTE_REPORT_DATA_RANGE].copy_from_slice(&report_data);
     Ok(GetQuoteResponse {
         quote: quote.quote.to_vec(),
         event_log: serde_json::to_string(&quote.event_log)