io.grpc.internal.TransportFrameUtil Maven / Gradle / Ivy
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package io.grpc.internal;
import static com.google.common.base.Charsets.US_ASCII;
import com.google.common.io.BaseEncoding;
import io.grpc.Metadata;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.logging.Logger;
/**
* Utility functions for transport layer framing.
*
* 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.
*
* @return the interleaved keys and values.
*/
public static byte[][] toHttp2Headers(Metadata headers) {
byte[][] serializedHeaders = headers.serialize();
ArrayList result = new ArrayList(serializedHeaders.length);
for (int i = 0; i < serializedHeaders.length; i += 2) {
byte[] key = serializedHeaders[i];
byte[] value = serializedHeaders[i + 1];
if (endsWith(key, binaryHeaderSuffixBytes)) {
// Binary header.
result.add(key);
result.add(BaseEncoding.base64().encode(value).getBytes(US_ASCII));
} 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)) {
result.add(key);
result.add(value);
} else {
String keyString = new String(key, US_ASCII);
logger.warning("Metadata key=" + keyString + ", value=" + Arrays.toString(value)
+ " contains invalid ASCII characters");
}
}
}
return result.toArray(new byte[result.size()][]);
}
/**
* Transform HTTP/2-compliant headers to the raw serialized format which can be deserialized by
* metadata marshallers. It decodes the Base64-encoded binary headers.
*
* @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) {
byte[][] result = new byte[http2Headers.length][];
for (int i = 0; i < http2Headers.length; i += 2) {
byte[] key = http2Headers[i];
byte[] value = http2Headers[i + 1];
result[i] = key;
if (endsWith(key, binaryHeaderSuffixBytes)) {
// Binary header
result[i + 1] = BaseEncoding.base64().decode(new String(value, US_ASCII));
} else {
// Non-binary header
result[i + 1] = value;
}
}
return result;
}
/**
* 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() {}
}