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lgoldstein pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/mina-sshd.git
commit 0dc159ab3bbac86ccd99a370c87518b9ea98866b
Author: Lyor Goldstein <lgoldst...@apache.org>
AuthorDate: Fri Feb 26 10:44:31 2021 +0200
[SSHD-1133] Added capability to specify a custom charset for parsing
incoming commands to the ScpShell
---
CHANGES.md | 3 +++
docs/scp.md | 13 +++++++++++++
.../main/java/org/apache/sshd/scp/ScpModuleProperties.java | 13 ++++++++++---
.../src/main/java/org/apache/sshd/scp/server/ScpShell.java | 5 +++--
4 files changed, 29 insertions(+), 5 deletions(-)
diff --git a/CHANGES.md b/CHANGES.md
index 6e44df8..6de775d 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -16,6 +16,8 @@
* [SSHD-1133](https://issues.apache.org/jira/browse/SSHD-1133) Re-factored
locations and names of `ServerSession` and server-side `ChannelSession` related
classes
+## Potential compatibility issues
+
## Minor code helpers
* [SSHD-525](https://issues.apache.org/jira/browse/SSHD-525) Added support for
SFTP **client-side** ["posix-ren...@openssh.com"
@@ -43,3 +45,4 @@
* [SSHD-1114](https://issues.apache.org/jira/browse/SSHD-1114) Added
capability for interactive key based authentication participation via
UserInteraction
* [SSHD-1125](https://issues.apache.org/jira/browse/SSHD-1125) Added mechanism
to throttle pending write requests in BufferedIoOutputStream
* [SSHD-1127](https://issues.apache.org/jira/browse/SSHD-1127) Added
capability to register a custom receiver for SFTP STDERR channel raw or stream
data
+* [SSHD-1133](https://issues.apache.org/jira/browse/SSHD-1133) Added
capability to specify a custom charset for parsing incoming commands to the
`ScpShell`
\ No newline at end of file
diff --git a/docs/scp.md b/docs/scp.md
index d7274b1..06364c1 100644
--- a/docs/scp.md
+++ b/docs/scp.md
@@ -191,6 +191,19 @@ sshd.setShellFactory(factory);
**Note:** a similar result can be achieved if activating SSHD from the command
line by specifying `-o ShellFactory=scp`
+### Text encoding/decoding
+
+The SCP "shell" is text-based and therefore subject to character
encoding/decoding of the data being exchanged. By default, the exchange is
supposed to use the UTF-8 encoding which is the default/standard one for SSH.
However, there are clients/servers "in the wild" that do not conform to this
convention. For this purpose, it is possible to define a different character
encoding via the `SHELL_NAME_EN/DECODING_CHARSET` properties - e.g.:
+
+```java
+SshServer sshd = ...setup server...
+// Can also use the character name string rather than the object instance
itself
+ScpModuleProperties.SHELL_NAME_ENCODING_CHARSET.set(sshd,
Charset.forName("US-ASCII"));
+ScpModuleProperties.SHELL_NAME_DECODING_CHARSET.set(sshd,
Charset.forName("US-ASCII"));
+```
+
+**Caveat emptor:** that the code does not enforce "symmetry" of the chosen
character sets - in other words, user can either by design or error cause
different encoding to be used for the incoming commands vs. the outgoing
responses. It is important to bear in mind that if the text to be
encoded/decoded contains characters that cannot be safely handled by the
chosen encoder/decoder than the result might not be correctly parsed/understood
by the peer.
+
## Remote-to-remote transfer
The code provides an `ScpTransferHelper` class that enables copying files
between 2 remote accounts without going through
diff --git
a/sshd-scp/src/main/java/org/apache/sshd/scp/ScpModuleProperties.java
b/sshd-scp/src/main/java/org/apache/sshd/scp/ScpModuleProperties.java
index 4821f34..4bdae9a 100644
--- a/sshd-scp/src/main/java/org/apache/sshd/scp/ScpModuleProperties.java
+++ b/sshd-scp/src/main/java/org/apache/sshd/scp/ScpModuleProperties.java
@@ -53,12 +53,19 @@ public final class ScpModuleProperties {
= Property.bool("scp-auto-sync-on-write", true);
/**
- * Used to indicate the {@link Charset} (or its name) for encoding
referenced files/folders names - extracted from
- * the client channel session when 1st initialized.
+ * Used to indicate the {@link Charset} (or its name) for encoding
returned textual responses from the
+ * {@code ScpShell} - extracted from the channel session when shell
initialized.
*/
- public static final Property<Charset> NAME_ENCODING_CHARSET
+ public static final Property<Charset> SHELL_NAME_ENCODING_CHARSET
= Property.charset("scp-shell-name-encoding-charset",
StandardCharsets.UTF_8);
+ /**
+ * Used to indicate the {@link Charset} (or its name) for decoding
incoming commands to be processed by the
+ * {@code ScpShell} - extracted from the channel session when shell
initialized.
+ */
+ public static final Property<Charset> SHELL_NAME_DECODING_CHARSET
+ = Property.charset("scp-shell-name-decoding-charset",
StandardCharsets.UTF_8);
+
private ScpModuleProperties() {
throw new UnsupportedOperationException("No instance");
}
diff --git a/sshd-scp/src/main/java/org/apache/sshd/scp/server/ScpShell.java
b/sshd-scp/src/main/java/org/apache/sshd/scp/server/ScpShell.java
index ca413be..af31fbc 100644
--- a/sshd-scp/src/main/java/org/apache/sshd/scp/server/ScpShell.java
+++ b/sshd-scp/src/main/java/org/apache/sshd/scp/server/ScpShell.java
@@ -106,7 +106,7 @@ public class ScpShell extends AbstractFileSystemCommand
implements ServerChannel
super(null, executorService);
this.channelSession = Objects.requireNonNull(channelSession, "No
channel session provided");
- nameEncodingCharset =
ScpModuleProperties.NAME_ENCODING_CHARSET.getRequired(channelSession);
+ nameEncodingCharset =
ScpModuleProperties.SHELL_NAME_ENCODING_CHARSET.getRequired(channelSession);
if (sendSize < ScpHelper.MIN_SEND_BUFFER_SIZE) {
throw new IllegalArgumentException(
@@ -185,9 +185,10 @@ public class ScpShell extends AbstractFileSystemCommand
implements ServerChannel
prepareEnvironment(getEnvironment());
+ Charset decodingCharset =
ScpModuleProperties.SHELL_NAME_DECODING_CHARSET.getRequired(channel);
// Use a special stream reader so that the stream can be used with
the scp command
try (InputStream inputStream = getInputStream();
- Reader r = new InputStreamReader(inputStream,
StandardCharsets.UTF_8)) {
+ Reader r = new InputStreamReader(inputStream,
decodingCharset)) {
for (int executedCommands = 0;; executedCommands++) {
command = readLine(r);
if (GenericUtils.isEmpty(command)) {
