From b740fe1af4a634997ba42c0df337305bad4ab47a Mon Sep 17 00:00:00 2001
From: Lev Khomich <levkhomich@gmail.com>
Date: Mon, 17 Oct 2016 17:17:18 +0500
Subject: [PATCH] tolerate up to 128-bit span ids by dropping higher bits (#84)

---
 .../akka/tracing/SpanMetadata.scala           | 30 +++++++++------
 .../akka/tracing/SpanMetadataSpec.scala       | 37 +++++++++++++++++--
 2 files changed, 51 insertions(+), 16 deletions(-)

diff --git a/core/src/main/scala/com/github/levkhomich/akka/tracing/SpanMetadata.scala b/core/src/main/scala/com/github/levkhomich/akka/tracing/SpanMetadata.scala
index a8ab322..ee744ca 100644
--- a/core/src/main/scala/com/github/levkhomich/akka/tracing/SpanMetadata.scala
+++ b/core/src/main/scala/com/github/levkhomich/akka/tracing/SpanMetadata.scala
@@ -71,19 +71,25 @@ object SpanMetadata {
   }
 
   private[tracing] def idFromString(x: String): Long = {
-    if (x == null || x.length == 0 || x.length > 16)
-      throw new NumberFormatException("Invalid span id string: " + x)
-    val s =
-      if (x.length % 2 == 0) x
-      else "0" + x
-    val bytes = new Array[Byte](8)
-    val start = 7 - (s.length + 1) / 2
-    (s.length until 0 by -2).foreach {
-      i =>
-        val x = Integer.parseInt(s.substring(i - 2, i), 16).toByte
-        bytes.update(start + i / 2, x)
+    if (x == null || x.length == 0) {
+      throw new NumberFormatException("Empty span id")
+    } else if (x.length > 32) {
+      throw new NumberFormatException("Span id is too long: " + x)
+    } else if (x.length > 16) {
+      idFromString(x.takeRight(16))
+    } else {
+      val s =
+        if (x.length % 2 == 0) x
+        else "0" + x
+      val bytes = new Array[Byte](8)
+      val start = 7 - (s.length + 1) / 2
+      (s.length until 0 by -2).foreach {
+        i =>
+          val x = Integer.parseInt(s.substring(i - 2, i), 16).toByte
+          bytes.update(start + i / 2, x)
+      }
+      new DataInputStream(new ByteArrayInputStream(bytes)).readLong
     }
-    new DataInputStream(new ByteArrayInputStream(bytes)).readLong
   }
 
   /**
diff --git a/core/src/test/scala/com/github/levkhomich/akka/tracing/SpanMetadataSpec.scala b/core/src/test/scala/com/github/levkhomich/akka/tracing/SpanMetadataSpec.scala
index 6efb8c7..e76126e 100644
--- a/core/src/test/scala/com/github/levkhomich/akka/tracing/SpanMetadataSpec.scala
+++ b/core/src/test/scala/com/github/levkhomich/akka/tracing/SpanMetadataSpec.scala
@@ -18,7 +18,7 @@ package com.github.levkhomich.akka.tracing
 
 import scala.util.Random
 
-import com.github.kristofa.brave.SpanId
+import com.github.kristofa.brave.{ IdConversion, SpanId }
 import org.specs2.mutable.Specification
 
 class SpanMetadataSpec extends Specification with TracingTestCommons {
@@ -54,7 +54,7 @@ class SpanMetadataSpec extends Specification with TracingTestCommons {
           failure(s"SpanId deserialization failed for value $x (was $actual instead of $expected)")
       }
 
-      checkValue("FFFFFFFFFFFFFFFF")
+      checkValue("ffffffffffffffff")
       checkValue("0")
       checkValue("00")
       checkValue("0000000000000000")
@@ -75,8 +75,37 @@ class SpanMetadataSpec extends Specification with TracingTestCommons {
       SpanMetadata.idFromString(null) must throwAn[NumberFormatException]
       SpanMetadata.idFromString("") must throwAn[NumberFormatException]
       SpanMetadata.idFromString("not a number") must throwAn[NumberFormatException]
-      SpanMetadata.idFromString("11111111111111111") must throwAn[NumberFormatException]
-      SpanMetadata.idFromString("11111111111111111") must throwAn[NumberFormatException]
+    }
+
+    "tolerate up to 128-bit span ids by dropping higher bits" in {
+      def checkValue(x: String): Unit = {
+        val actual = SpanMetadata.idFromString(x)
+        val expected = IdConversion.convertToLong(x)
+        if (actual != expected)
+          failure(s"SpanId deserialization failed for value $x (was $actual instead of $expected)")
+      }
+
+      checkValue("463ac35c9f6413ad48485a3953bb612412") should throwA[NumberFormatException]
+
+      checkValue("463ac35c9f6413ad48485a3953bb6124")
+      checkValue("463ac35c9f6413ad48485a3953")
+      checkValue("463ac35c9f6413ad48485")
+      checkValue("463ac35c9f6413ad")
+      checkValue("ffffffffffffffffffffffffffffffff")
+      checkValue("0")
+      checkValue("00")
+      checkValue("00000000000000000000000000000000")
+      checkValue("1")
+      checkValue("11")
+      checkValue("111")
+
+      for (_ <- 1L to IterationsCount)
+        checkValue {
+          val str = Random.nextLong().toString.replace("-", "")
+          str.substring(0, (Random.nextInt(15) + 1) min str.length)
+        }
+
+      success
     }
 
     "provide metadata [de]serialization support" in {