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/*
* Copyright 2014, gRPC Authors All rights reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package io.grpc.internal;
import static com.google.common.base.Charsets.US_ASCII;
import com.google.common.io.BaseEncoding;
import io.grpc.InternalMetadata;
import io.grpc.Metadata;
import java.util.Arrays;
import java.util.logging.Logger;
/**
* Utility functions for transport layer framing.
*
* <p>Within a given transport frame we reserve the first byte to indicate the type of compression
* used for the contents of the transport frame.
*/
public final class TransportFrameUtil {
private static final Logger logger = Logger.getLogger(TransportFrameUtil.class.getName());
private static final byte[] binaryHeaderSuffixBytes =
Metadata.BINARY_HEADER_SUFFIX.getBytes(US_ASCII);
/**
* Transform the given headers to a format where only spec-compliant ASCII characters are allowed.
* Binary header values are encoded by Base64 in the result. It is safe to modify the returned
* array, but not to modify any of the underlying byte arrays.
*
* @return the interleaved keys and values.
*/
public static byte[][] toHttp2Headers(Metadata headers) {
byte[][] serializedHeaders = InternalMetadata.serialize(headers);
// TODO(carl-mastrangelo): eventually remove this once all callers are updated.
if (serializedHeaders == null) {
return new byte[][]{};
}
int k = 0;
for (int i = 0; i < serializedHeaders.length; i += 2) {
byte[] key = serializedHeaders[i];
byte[] value = serializedHeaders[i + 1];
if (endsWith(key, binaryHeaderSuffixBytes)) {
// Binary header.
serializedHeaders[k] = key;
serializedHeaders[k + 1] = BaseEncoding.base64().encode(value).getBytes(US_ASCII);
k += 2;
} else {
// Non-binary header.
// Filter out headers that contain non-spec-compliant ASCII characters.
// TODO(zhangkun83): only do such check in development mode since it's expensive
if (isSpecCompliantAscii(value)) {
serializedHeaders[k] = key;
serializedHeaders[k + 1] = value;
k += 2;
} else {
String keyString = new String(key, US_ASCII);
logger.warning("Metadata key=" + keyString + ", value=" + Arrays.toString(value)
+ " contains invalid ASCII characters");
}
}
}
// Fast path, everything worked out fine.
if (k == serializedHeaders.length) {
return serializedHeaders;
}
return Arrays.copyOfRange(serializedHeaders, 0, k);
}
/**
* Transform HTTP/2-compliant headers to the raw serialized format which can be deserialized by
* metadata marshallers. It decodes the Base64-encoded binary headers. This function modifies
* the headers in place. By modifying the input array.
*
* @param http2Headers the interleaved keys and values of HTTP/2-compliant headers
* @return the interleaved keys and values in the raw serialized format
*/
public static byte[][] toRawSerializedHeaders(byte[][] http2Headers) {
for (int i = 0; i < http2Headers.length; i += 2) {
byte[] key = http2Headers[i];
byte[] value = http2Headers[i + 1];
http2Headers[i] = key;
if (endsWith(key, binaryHeaderSuffixBytes)) {
// Binary header
http2Headers[i + 1] = BaseEncoding.base64().decode(new String(value, US_ASCII));
} else {
// Non-binary header
// Nothing to do, the value is already in the right place.
}
}
return http2Headers;
}
/**
* Returns {@code true} if {@code subject} ends with {@code suffix}.
*/
private static boolean endsWith(byte[] subject, byte[] suffix) {
int start = subject.length - suffix.length;
if (start < 0) {
return false;
}
for (int i = start; i < subject.length; i++) {
if (subject[i] != suffix[i - start]) {
return false;
}
}
return true;
}
/**
* Returns {@code true} if {@code subject} contains only bytes that are spec-compliant ASCII
* characters and space.
*/
private static boolean isSpecCompliantAscii(byte[] subject) {
for (byte b : subject) {
if (b < 32 || b > 126) {
return false;
}
}
return true;
}
private TransportFrameUtil() {}
}
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