Ensure P4Runtime byte strings are padded to their bit width
The P4Runtime server may send canonical byte strings (i.e.,
non-padded byte strings).
In ONOS we ensure, in the codecs, that all byte strings are
padded to match the model (P4Info) bit width. In this way,
we provide read-write symmetry inside ONOS.
ONOS always pads byte strings when sending messages to the
P4Runtime server.
This patch doesn't enforce read-write symmetry between
P4Runtime client and server on the wire.
N.B.: the current padding implementation works ONLY when
using non-negative integer.
Change-Id: I9f8e43de015bd0929dd543d7688c8e71bf5fe98d
diff --git a/utils/misc/src/main/java/org/onlab/util/ImmutableByteSequence.java b/utils/misc/src/main/java/org/onlab/util/ImmutableByteSequence.java
index 1710d29..32e9d0b 100644
--- a/utils/misc/src/main/java/org/onlab/util/ImmutableByteSequence.java
+++ b/utils/misc/src/main/java/org/onlab/util/ImmutableByteSequence.java
@@ -190,6 +190,53 @@
}
/**
+ * Creates a new immutable byte sequence while trimming or expanding the
+ * content of the given byte buffer to fit the given bit-width. Calling this
+ * method has the same behavior as
+ * {@code ImmutableByteSequence.copyFrom(original).fit(bitWidth)}.
+ *
+ * @param original a byte buffer value
+ * @param bitWidth a non-zero positive integer
+ * @return a new immutable byte sequence
+ * @throws ByteSequenceTrimException if the byte buffer cannot be fitted
+ */
+ public static ImmutableByteSequence copyAndFit(ByteBuffer original, int bitWidth)
+ throws ByteSequenceTrimException {
+ checkArgument(original != null && original.capacity() > 0,
+ "Cannot copy from an empty or null byte buffer");
+ checkArgument(bitWidth > 0,
+ "bit-width must be a non-zero positive integer");
+ if (original.order() == ByteOrder.LITTLE_ENDIAN) {
+ // FIXME: this can be improved, e.g. read bytes in reverse order from original
+ byte[] newBytes = new byte[original.capacity()];
+ original.get(newBytes);
+ reverse(newBytes);
+ return internalCopyAndFit(ByteBuffer.wrap(newBytes), bitWidth);
+ } else {
+ return internalCopyAndFit(original.duplicate(), bitWidth);
+ }
+ }
+
+ private static ImmutableByteSequence internalCopyAndFit(ByteBuffer byteBuf, int bitWidth)
+ throws ByteSequenceTrimException {
+ final int byteWidth = (bitWidth + 7) / 8;
+ final ByteBuffer newByteBuffer = ByteBuffer.allocate(byteWidth);
+ byteBuf.rewind();
+ if (byteWidth >= byteBuf.capacity()) {
+ newByteBuffer.position(byteWidth - byteBuf.capacity());
+ newByteBuffer.put(byteBuf);
+ } else {
+ for (int i = 0; i < byteBuf.capacity() - byteWidth; i++) {
+ if (byteBuf.get(i) != 0) {
+ throw new ByteSequenceTrimException(byteBuf, bitWidth);
+ }
+ }
+ newByteBuffer.put(byteBuf.position(byteBuf.capacity() - byteWidth));
+ }
+ return new ImmutableByteSequence(newByteBuffer);
+ }
+
+ /**
* Creates a new byte sequence of the given size where all bits are 0.
*
* @param size number of bytes
@@ -500,12 +547,17 @@
}
/**
- * Signals that a byte sequence cannot be trimmed.
+ * Signals a trim exception during byte sequence creation.
*/
public static class ByteSequenceTrimException extends Exception {
ByteSequenceTrimException(ImmutableByteSequence original, int bitWidth) {
super(format("cannot trim %s into a %d bits long value",
original, bitWidth));
}
+
+ ByteSequenceTrimException(ByteBuffer original, int bitWidth) {
+ super(format("cannot trim %s (ByteBuffer) into a %d bits long value",
+ original, bitWidth));
+ }
}
}
diff --git a/utils/misc/src/test/java/org/onlab/util/ImmutableByteSequenceTest.java b/utils/misc/src/test/java/org/onlab/util/ImmutableByteSequenceTest.java
index 7e74328..c83c6b2 100644
--- a/utils/misc/src/test/java/org/onlab/util/ImmutableByteSequenceTest.java
+++ b/utils/misc/src/test/java/org/onlab/util/ImmutableByteSequenceTest.java
@@ -25,6 +25,7 @@
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
+import java.util.Arrays;
import java.util.Random;
import static java.lang.Integer.max;
@@ -81,6 +82,107 @@
}
@Test
+ public void testCopyAndFit() throws Exception {
+ int originalByteWidth = 3;
+ int paddedByteWidth = 4;
+ int trimmedByteWidth = 2;
+ int indexFirstNonZeroByte = 1;
+
+ byte byteValue = (byte) 1;
+ byte[] arrayValue = new byte[originalByteWidth];
+ arrayValue[indexFirstNonZeroByte] = byteValue;
+ ByteBuffer bufferValue = ByteBuffer.allocate(originalByteWidth).put(arrayValue);
+
+ ImmutableByteSequence bsBuffer = ImmutableByteSequence.copyAndFit(
+ bufferValue, originalByteWidth * 8);
+ ImmutableByteSequence bsBufferTrimmed = ImmutableByteSequence.copyAndFit(
+ bufferValue, trimmedByteWidth * 8);
+ ImmutableByteSequence bsBufferPadded = ImmutableByteSequence.copyAndFit(
+ bufferValue, paddedByteWidth * 8);
+
+ assertThat("byte sequence of the byte buffer must be 3 bytes long",
+ bsBuffer.size(), is(equalTo(originalByteWidth)));
+ assertThat("byte sequence of the byte buffer must be 3 bytes long",
+ bsBufferTrimmed.size(), is(equalTo(trimmedByteWidth)));
+ assertThat("byte sequence of the byte buffer must be 3 bytes long",
+ bsBufferPadded.size(), is(equalTo(paddedByteWidth)));
+
+ String errStr = "incorrect byte sequence value";
+
+ assertThat(errStr, bsBuffer.asArray()[indexFirstNonZeroByte], is(equalTo(byteValue)));
+ assertThat(errStr, bsBufferTrimmed.asArray()[indexFirstNonZeroByte - 1], is(equalTo(byteValue)));
+ assertThat(errStr, bsBufferPadded.asArray()[indexFirstNonZeroByte + 1], is(equalTo(byteValue)));
+ assertThat(errStr, bsBufferPadded.asArray()[paddedByteWidth - 1], is(equalTo((byte) 0x00)));
+ }
+
+ @Test
+ public void testCopyAndFitEndianness() throws Exception {
+ int originalByteWidth = 4;
+ int indexByteNonZeroBig = 1;
+ int indexByteNonZeroLittle = 2;
+ byte byteValue = (byte) 1;
+
+ ByteBuffer bbBigEndian = ByteBuffer
+ .allocate(originalByteWidth)
+ .order(ByteOrder.BIG_ENDIAN);
+ bbBigEndian.put(indexByteNonZeroBig, byteValue);
+ ImmutableByteSequence bsBufferCopyBigEndian =
+ ImmutableByteSequence.copyAndFit(bbBigEndian, originalByteWidth * 8);
+
+ ByteBuffer bbLittleEndian = ByteBuffer
+ .allocate(originalByteWidth)
+ .order(ByteOrder.LITTLE_ENDIAN);
+ bbLittleEndian.put(indexByteNonZeroLittle, byteValue);
+ ImmutableByteSequence bsBufferCopyLittleEndian =
+ ImmutableByteSequence.copyAndFit(bbLittleEndian, originalByteWidth * 8);
+
+ // creates a new sequence from primitive type
+ byte[] arrayValue = new byte[originalByteWidth];
+ arrayValue[indexByteNonZeroBig] = byteValue;
+ ImmutableByteSequence bsArrayCopy =
+ ImmutableByteSequence.copyFrom(arrayValue);
+
+ new EqualsTester()
+ // big-endian byte array cannot be equal to little-endian array
+ .addEqualityGroup(bbBigEndian.array())
+ .addEqualityGroup(bbLittleEndian.array())
+ // all byte sequences must be equal
+ .addEqualityGroup(bsBufferCopyBigEndian,
+ bsBufferCopyLittleEndian,
+ bsArrayCopy)
+ // byte buffer views of all sequences must be equal
+ .addEqualityGroup(bsBufferCopyBigEndian.asReadOnlyBuffer(),
+ bsBufferCopyLittleEndian.asReadOnlyBuffer(),
+ bsArrayCopy.asReadOnlyBuffer())
+ // byte buffer orders of all sequences must be ByteOrder.BIG_ENDIAN
+ .addEqualityGroup(bsBufferCopyBigEndian.asReadOnlyBuffer().order(),
+ bsBufferCopyLittleEndian.asReadOnlyBuffer().order(),
+ bsArrayCopy.asReadOnlyBuffer().order(),
+ ByteOrder.BIG_ENDIAN)
+ .testEquals();
+ }
+
+ @Test
+ public void testIllegalCopyAndFit() throws Exception {
+ int originalByteWidth = 3;
+ int trimmedByteWidth = 1;
+ int indexFirstNonZeroByte = 1;
+
+ byte byteValue = (byte) 1;
+ byte[] arrayValue = new byte[originalByteWidth];
+ arrayValue[indexFirstNonZeroByte] = byteValue;
+ ByteBuffer bufferValue = ByteBuffer.allocate(originalByteWidth).put(arrayValue);
+
+ try {
+ ImmutableByteSequence.copyAndFit(bufferValue, trimmedByteWidth * 8);
+ Assert.fail(format("Expect ByteSequenceTrimException due to value = %s and bitWidth %d",
+ Arrays.toString(arrayValue), trimmedByteWidth * 8));
+ } catch (ImmutableByteSequence.ByteSequenceTrimException e) {
+ // We expect this.
+ }
+ }
+
+ @Test
public void testEndianness() throws Exception {
long longValue = RandomUtils.nextLong();