sdk: reject corrupted and truncated timestamp index data

Error on next_entry_index > MAX in Python/TS (Go already did this).
Error on truncated entry data in all three SDKs instead of silently
returning partial or zero-value entries.

Author: snormore

sdk/telemetry/go/state.go

@@ -173,11 +173,12 @@ func DeserializeTimestampIndex(data []byte) (*TimestampIndex, error) {
 		return nil, fmt.Errorf("next_entry_index %d exceeds max %d", count, MaxTimestampIndexEntries)
 	}
 
+	if r.Remaining() < count*timestampIndexEntrySize {
+		return nil, fmt.Errorf("data too short for %d timestamp index entries: %d < %d", count, r.Remaining(), count*timestampIndexEntrySize)
+	}
+
 	d.Entries = make([]TimestampIndexEntry, count)
 	for i := range count {
-		if r.Remaining() < timestampIndexEntrySize {
-			break
-		}
 		d.Entries[i].SampleIndex, _ = r.ReadU32()
 		d.Entries[i].TimestampMicroseconds, _ = r.ReadU64()
 	}

sdk/telemetry/python/telemetry/state.py

@@ -172,11 +172,20 @@ def from_bytes(cls, data: bytes) -> TimestampIndex:
 
         r.read_bytes(64)  # reserved
 
-        count = min(next_entry_index, MAX_TIMESTAMP_INDEX_ENTRIES)
+        if next_entry_index > MAX_TIMESTAMP_INDEX_ENTRIES:
+            raise ValueError(
+                f"next_entry_index {next_entry_index} exceeds max {MAX_TIMESTAMP_INDEX_ENTRIES}"
+            )
+
+        count = next_entry_index
+        if r.remaining < count * TIMESTAMP_INDEX_ENTRY_SIZE:
+            raise ValueError(
+                f"data too short for {count} timestamp index entries: "
+                f"{r.remaining} < {count * TIMESTAMP_INDEX_ENTRY_SIZE}"
+            )
+
         entries: list[TimestampIndexEntry] = []
         for _ in range(count):
-            if r.remaining < TIMESTAMP_INDEX_ENTRY_SIZE:
-                break
             sample_index = r.read_u32()
             timestamp_microseconds = r.read_u64()
             entries.append(TimestampIndexEntry(sample_index, timestamp_microseconds))

sdk/telemetry/typescript/telemetry/state.ts

@@ -161,10 +161,21 @@ export function deserializeTimestampIndex(
 
   r.readBytes(64); // _unused
 
-  const count = Math.min(nextEntryIndex, MAX_TIMESTAMP_INDEX_ENTRIES);
+  if (nextEntryIndex > MAX_TIMESTAMP_INDEX_ENTRIES) {
+    throw new Error(
+      `next_entry_index ${nextEntryIndex} exceeds max ${MAX_TIMESTAMP_INDEX_ENTRIES}`,
+    );
+  }
+
+  const count = nextEntryIndex;
+  if (r.remaining < count * TIMESTAMP_INDEX_ENTRY_SIZE) {
+    throw new Error(
+      `data too short for ${count} timestamp index entries: ${r.remaining} < ${count * TIMESTAMP_INDEX_ENTRY_SIZE}`,
+    );
+  }
+
   const entries: TimestampIndexEntry[] = [];
   for (let i = 0; i < count; i++) {
-    if (r.remaining < TIMESTAMP_INDEX_ENTRY_SIZE) break;
     entries.push({
       sampleIndex: r.readU32(),
       timestampMicroseconds: r.readU64(),