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Reimplemented parsing the identification (Fixes #176)
This ensures that any header lines sent before the identification string do not break the identification parsing if they are longer than the identification string should be.
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src/main/java/com/hierynomus/sshj/transport/IdentificationStringParser.java
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,83 @@ | ||
| /* | ||
| * Copyright (C)2009 - SSHJ Contributors | ||
| * | ||
| * 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 com.hierynomus.sshj.transport; | ||
|
|
||
| import net.schmizz.sshj.common.Buffer; | ||
| import net.schmizz.sshj.common.ByteArrayUtils; | ||
| import net.schmizz.sshj.transport.TransportException; | ||
| import org.slf4j.Logger; | ||
| import org.slf4j.LoggerFactory; | ||
|
|
||
| import java.io.IOException; | ||
| import java.util.Arrays; | ||
|
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| public class IdentificationStringParser { | ||
| private static final Logger logger = LoggerFactory.getLogger(IdentificationStringParser.class); | ||
| private final Buffer.PlainBuffer buffer; | ||
|
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| private byte[] EXPECTED_START_BYTES = new byte[] {'S', 'S', 'H', '-'}; | ||
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| public IdentificationStringParser(Buffer.PlainBuffer buffer) { | ||
| this.buffer = buffer; | ||
| } | ||
|
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| public String parseIdentificationString() throws IOException { | ||
| for (;;) { | ||
| Buffer.PlainBuffer lineBuffer = new Buffer.PlainBuffer(); | ||
| int lineStartPos = buffer.rpos(); | ||
| for (;;) { | ||
| if (buffer.available() == 0) { | ||
| buffer.rpos(lineStartPos); | ||
| return ""; | ||
| } | ||
| byte b = buffer.readByte(); | ||
| lineBuffer.putByte(b); | ||
| if (b == '\n') { | ||
| if (checkForIdentification(lineBuffer)) { | ||
| return readIdentification(lineBuffer); | ||
| } | ||
| break; | ||
| } | ||
| } | ||
| } | ||
| } | ||
|
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| private String readIdentification(Buffer.PlainBuffer lineBuffer) throws Buffer.BufferException, TransportException { | ||
| byte[] bytes = new byte[lineBuffer.available()]; | ||
| lineBuffer.readRawBytes(bytes); | ||
| if (bytes.length > 255) { | ||
| logger.error("Incorrect identification String received, line was longer than expected: {}", new String(bytes)); | ||
| logger.error("Just for good measure, bytes were: {}", ByteArrayUtils.printHex(bytes, 0, bytes.length)); | ||
| throw new TransportException("Incorrect identification: line too long: " + ByteArrayUtils.printHex(bytes, 0, bytes.length)); | ||
| } | ||
| if (bytes[bytes.length - 2] != '\r') { | ||
| logger.error("Incorrect identification, was expecting a '\\r\\n' however got: '{}' (hex: {})", bytes[bytes.length - 2], Integer.toHexString(bytes[bytes.length - 2] & 0xFF)); | ||
| logger.error("Data received up til here was: {}", new String(bytes)); | ||
| throw new TransportException("Incorrect identification: bad line ending: " + ByteArrayUtils.toHex(bytes, 0, bytes.length)); | ||
| } | ||
|
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| // Strip off the \r\n | ||
| return new String(bytes, 0, bytes.length - 2); | ||
| } | ||
|
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| private boolean checkForIdentification(Buffer.PlainBuffer lineBuffer) throws Buffer.BufferException { | ||
| byte[] buf = new byte[4]; | ||
| lineBuffer.readRawBytes(buf); | ||
| // Reset | ||
| lineBuffer.rpos(0); | ||
| return Arrays.equals(EXPECTED_START_BYTES, buf); | ||
| } | ||
| } |
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78
src/test/groovy/com/hierynomus/sshj/transport/IdentificationStringParserSpec.groovy
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,78 @@ | ||
| /* | ||
| * Copyright (C)2009 - SSHJ Contributors | ||
| * | ||
| * 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 com.hierynomus.sshj.transport | ||
|
|
||
| import net.schmizz.sshj.common.Buffer | ||
| import net.schmizz.sshj.transport.TransportException | ||
| import spock.lang.Specification | ||
|
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| class IdentificationStringParserSpec extends Specification { | ||
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| def "should parse simple identification string"() { | ||
| given: | ||
| def buffer = new Buffer.PlainBuffer() | ||
| buffer.putRawBytes("SSH-2.0-OpenSSH-6.13\r\n".bytes) | ||
|
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| when: | ||
| def ident = new IdentificationStringParser(buffer).parseIdentificationString() | ||
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| then: | ||
| ident == "SSH-2.0-OpenSSH-6.13" | ||
| } | ||
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| def "should not parse header lines as part of ident"() { | ||
| given: | ||
| def buffer = new Buffer.PlainBuffer() | ||
| buffer.putRawBytes("header1\nheader2\r\nSSH-2.0-OpenSSH-6.13\r\n".bytes) | ||
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| when: | ||
| def ident = new IdentificationStringParser(buffer).parseIdentificationString() | ||
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| then: | ||
| ident == "SSH-2.0-OpenSSH-6.13" | ||
| } | ||
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| def "should fail on too long ident string"() { | ||
| given: | ||
| def buffer = new Buffer.PlainBuffer() | ||
| buffer.putRawBytes("SSH-2.0-OpenSSH-6.13 ".bytes) | ||
| byte[] bs = new byte[255 - buffer.wpos()] | ||
| Arrays.fill(bs, 'a'.bytes[0]) | ||
| buffer.putRawBytes(bs).putRawBytes("\r\n".bytes) | ||
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| when: | ||
| new IdentificationStringParser(buffer).parseIdentificationString() | ||
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| then: | ||
| thrown(TransportException.class) | ||
| } | ||
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| def "should not fail on too long header line"() { | ||
| given: | ||
| def buffer = new Buffer.PlainBuffer() | ||
| buffer.putRawBytes("header1 ".bytes) | ||
| byte[] bs = new byte[255 - buffer.wpos()] | ||
| new Random().nextBytes(bs) | ||
| buffer.putRawBytes(bs).putRawBytes("\r\n".bytes) | ||
| buffer.putRawBytes("SSH-2.0-OpenSSH-6.13\r\n".bytes) | ||
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| when: | ||
| def ident = new IdentificationStringParser(buffer).parseIdentificationString() | ||
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| then: | ||
| ident == "SSH-2.0-OpenSSH-6.13" | ||
| } | ||
| } |