Merge pull request #12 from compscidr/jason/bug-fix-dump-partial-buffer

bugfix, dumping partial buffer
compscidr · Aug 16, 2024 · 15b26ed · 15b26ed
2 parents 7bede70 + 145e052
commit 15b26ed
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Showing 5 changed files with 33 additions and 4 deletions.
diff --git a/...etdumper/src/main/kotlin/com/jasonernst/packetdumper/filedumper/PcapNgFilePacketDumper.kt b/...etdumper/src/main/kotlin/com/jasonernst/packetdumper/filedumper/PcapNgFilePacketDumper.kt
@@ -49,12 +49,15 @@ class PcapNgFilePacketDumper(
         addresses: Boolean,
         etherType: EtherType?,
     ) {
+        val startingPosition = buffer.position()
+        val originalLimit = buffer.limit()
         // optionally prepend the ethernet dummy header
         val conversionBuffer =
             if (etherType != null) {
                 prependDummyHeader(buffer, offset, length, etherType)
             } else {
-                buffer
+                val actualLimit = minOf(originalLimit, offset + length)
+                buffer.limit(actualLimit)
             }
 
         if (isSimple) {
@@ -67,5 +70,7 @@ class PcapNgFilePacketDumper(
             outputStreamWriter.write(packetBlock.toBytes())
             outputStreamWriter.flush()
         }
+        buffer.position(startingPosition)
+        buffer.limit(originalLimit)
     }
 }
diff --git a/...r/src/main/kotlin/com/jasonernst/packetdumper/serverdumper/PcapNgTcpServerPacketDumper.kt b/...r/src/main/kotlin/com/jasonernst/packetdumper/serverdumper/PcapNgTcpServerPacketDumper.kt
@@ -133,11 +133,14 @@ class PcapNgTcpServerPacketDumper(
             // if there are no connected clients, no reason to dump
             return
         }
+        val startingPosition = buffer.position()
+        val originalLimit = buffer.limit()
         val conversionBuffer =
             if (etherType != null) {
                 prependDummyHeader(buffer, offset, length, etherType)
             } else {
-                buffer
+                val actualLimit = minOf(originalLimit, offset + length)
+                buffer.limit(actualLimit)
             }
         val packetBlock =
             if (isSimple) {
@@ -146,6 +149,8 @@ class PcapNgTcpServerPacketDumper(
                 // todo: timestamp
                 PcapNgEnhancedPacketBlock(conversionBuffer.array())
             }
+        buffer.position(startingPosition)
+        buffer.limit(originalLimit)
 
         with(connectionQueue.iterator()) {
             forEach {

diff --git a/packetdumper/src/main/kotlin/com/jasonernst/packetdumper/stringdumper/StringPacketDumper.kt b/packetdumper/src/main/kotlin/com/jasonernst/packetdumper/stringdumper/StringPacketDumper.kt
@@ -71,12 +71,14 @@ class StringPacketDumper(
         etherType: EtherType? = null,
     ): String {
         val startingPosition = buffer.position()
+        val originalLimit = buffer.limit()
         // optionally prepend the ethernet dummy header
         val conversionBuffer =
             if (etherType != null) {
                 prependDummyHeader(buffer, offset, length, etherType)
             } else {
-                buffer
+                val actualLimit = minOf(originalLimit, offset + length)
+                buffer.limit(actualLimit)
             }
 
         var totalLength = 0
@@ -103,6 +105,7 @@ class StringPacketDumper(
             }
         }
         buffer.position(startingPosition)
+        buffer.limit(originalLimit)
         return output.toString()
     }
 }
diff --git a/...dumper/src/test/kotlin/com/jasonernst/packetdumper/filedumper/TestTextFilePacketDumper.kt b/...dumper/src/test/kotlin/com/jasonernst/packetdumper/filedumper/TestTextFilePacketDumper.kt
@@ -28,10 +28,12 @@ class TestTextFilePacketDumper {
         buffer: ByteBuffer,
         addresses: Boolean = false,
         etherType: EtherType? = null,
+        offset: Int = 0,
+        length: Int = buffer.limit(),
     ): ByteBuffer {
         val stringDumper = StringPacketDumper()
         logger.debug("write buffer: ${stringDumper.dumpBufferToString(buffer, 0, buffer.limit())}")
-        dumper.dumpBuffer(buffer, 0, buffer.limit(), addresses, etherType)
+        dumper.dumpBuffer(buffer, offset, length, addresses, etherType)
         dumper.close()
         return TextFilePacketDumper.parseFile(dumper.filename, addresses, etherType)
     }
@@ -102,6 +104,14 @@ class TestTextFilePacketDumper {
         assertEquals(buffer, readBuffer)
     }
 
+    @Test fun shorterDumpThanLimit() {
+        dumper.open()
+        val buffer = ByteBuffer.wrap(byteArrayOf(0x00, 0x01, 0x02, 0x03, 0x04))
+        val readBuffer = writeReadBuffer(buffer, addresses = true, etherType = EtherType.IPv4, 0, buffer.limit() - 2)
+        buffer.limit(buffer.limit() - 2) // this will effectively remove the last two bytes
+        assertEquals(buffer, readBuffer)
+    }
+
     @Test
     fun testRealFileDump() {
         // this file has shorter addresses than we normally output, make sure it can be handled

diff --git a/...dumper/src/test/kotlin/com/jasonernst/packetdumper/stringdumper/TestStringPacketDumper.kt b/...dumper/src/test/kotlin/com/jasonernst/packetdumper/stringdumper/TestStringPacketDumper.kt
@@ -669,4 +669,10 @@ class TestStringPacketDumper {
         val hexString = stringPacketDumper.dumpBufferToString(buffer, 0, buffer.limit(), true, EtherType.IPv4)
         assertEquals("00000000  14 C0 3E 55 0B 35 74 D0 2B 29 A5 18 08 00 00 01\n00000010  02 03 04", hexString)
     }
+
+    @Test fun shorterDumpThanLimit() {
+        val buffer = ByteBuffer.wrap(byteArrayOf(0x00, 0x01, 0x02, 0x03, 0x04))
+        val hexString = stringPacketDumper.dumpBufferToString(buffer, 0, buffer.limit() - 2, false)
+        assertEquals("00 01 02", hexString)
+    }
 }