add lineage header validation

Author: ezhang6811

propagators/propagator-aws-xray/src/AWSXRayPropagator.ts

@@ -51,6 +51,10 @@ const IS_SAMPLED = '1';
 const NOT_SAMPLED = '0';
 
 const LINEAGE_KEY = "Lineage";
+const LINEAGE_DELIMITER = ":";
+const LINEAGE_HASH_LENGTH = 8;
+const LINEAGE_MAX_REQUEST_COUNTER = 255;
+const LINEAGE_MAX_LOOP_COUNTER = 32767;
 
 /**
  * Implementation of the AWS X-Ray Trace Header propagation protocol. See <a href=
@@ -162,7 +166,9 @@ export class AWSXRayPropagator implements TextMapPropagator {
       } else if (trimmedPart.startsWith(SAMPLED_FLAG_KEY)) {
         parsedTraceFlags = AWSXRayPropagator._parseTraceFlag(value);
       } else if (trimmedPart.startsWith(LINEAGE_KEY)) {
-        baggage = baggage.setEntry(LINEAGE_KEY, {value});
+        if (AWSXRayPropagator._isValidLineageV2Header(value)) {
+          baggage = baggage.setEntry(LINEAGE_KEY, {value});
+        }
       }
     }
     if (parsedTraceFlags === null) {
@@ -225,6 +231,23 @@ export class AWSXRayPropagator implements TextMapPropagator {
     return isValidSpanId(xrayParentId) ? xrayParentId : INVALID_SPANID;
   }
 
+  private static _isValidLineageV2Header(xrayLineageHeader: string): boolean {
+    const lineageSubstrings = xrayLineageHeader.split(LINEAGE_DELIMITER);
+    if (lineageSubstrings.length != 3) {
+      return false;
+    }
+
+    const requestCounter = parseInt(lineageSubstrings[0]);
+    const hashedResourceId = lineageSubstrings[1];
+    const loopCounter = parseInt(lineageSubstrings[2]);
+  
+    const isValidKey = hashedResourceId.length == LINEAGE_HASH_LENGTH && !!hashedResourceId.match(/^[0-9a-fA-F]+$/);
+    const isValidRequestCounter = requestCounter >= 0 && requestCounter <= LINEAGE_MAX_REQUEST_COUNTER;
+    const isValidLoopCounter = loopCounter >= 0 && loopCounter <= LINEAGE_MAX_LOOP_COUNTER;
+
+    return isValidKey && isValidRequestCounter && isValidLoopCounter;
+  }
+
   private static _parseTraceFlag(xraySampledFlag: string): TraceFlags | null {
     if (xraySampledFlag === NOT_SAMPLED) {
       return TraceFlags.NONE;