guacamole-spice-protocol/src/protocols/ssh/sftp.c

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/*
* Copyright (C) 2013 Glyptodon LLC
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
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#include "config.h"
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#include "client.h"
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#include "sftp.h"
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#include <fcntl.h>
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#include <libgen.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
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#include <libssh2_sftp.h>
#include <guacamole/client.h>
#include <guacamole/object.h>
#include <guacamole/protocol.h>
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#include <guacamole/socket.h>
#include <guacamole/stream.h>
/**
* Concatenates the given filename with the given path, separating the two
* with a single forward slash. The full result must be no more than
* GUAC_SFTP_MAX_PATH bytes long, counting null terminator.
*
* @param fullpath
* The buffer to store the result within. This buffer must be at least
* GUAC_SFTP_MAX_PATH bytes long.
*
* @param path
* The path to append the filename to.
*
* @param filename
* The filename to appaned to the path.
*
* @return
* true if the filename is valid and was successfully appended to the path,
* false otherwise.
*/
static bool guac_ssh_append_filename(char* fullpath, const char* path,
const char* filename) {
int i;
/* Disallow "." as a filename */
if (strcmp(filename, ".") == 0)
return false;
/* Disallow ".." as a filename */
if (strcmp(filename, "..") == 0)
return false;
/* Copy path, append trailing slash */
for (i=0; i<GUAC_SFTP_MAX_PATH; i++) {
/*
* Append trailing slash only if:
* 1) Trailing slash is not already present
* 2) Path is non-empty
*/
char c = path[i];
if (c == '\0') {
if (i > 0 && path[i-1] != '/')
fullpath[i++] = '/';
break;
}
/* Copy character if not end of string */
fullpath[i] = c;
}
/* Append filename */
for (; i<GUAC_SFTP_MAX_PATH; i++) {
char c = *(filename++);
if (c == '\0')
break;
/* Filenames may not contain slashes */
if (c == '\\' || c == '/')
return false;
/* Append each character within filename */
fullpath[i] = c;
}
/* Verify path length is within maximum */
if (i == GUAC_SFTP_MAX_PATH)
return false;
/* Terminate path string */
fullpath[i] = '\0';
/* Append was successful */
return true;
}
int guac_sftp_file_handler(guac_client* client, guac_stream* stream,
char* mimetype, char* filename) {
ssh_guac_client_data* client_data = (ssh_guac_client_data*) client->data;
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char fullpath[GUAC_SFTP_MAX_PATH];
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LIBSSH2_SFTP_HANDLE* file;
/* Concatenate filename with path */
if (!guac_ssh_append_filename(fullpath,
client_data->sftp_upload_path, filename)) {
guac_client_log(client, GUAC_LOG_DEBUG,
"Filename \"%s\" is invalid or resulting path is too long",
filename);
/* Abort transfer - invalid filename */
guac_protocol_send_ack(client->socket, stream,
"SFTP: Illegal filename",
GUAC_PROTOCOL_STATUS_CLIENT_BAD_REQUEST);
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guac_socket_flush(client->socket);
return 0;
}
/* Open file via SFTP */
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file = libssh2_sftp_open(client_data->sftp_session, fullpath,
LIBSSH2_FXF_WRITE | LIBSSH2_FXF_CREAT | LIBSSH2_FXF_TRUNC,
S_IRUSR | S_IWUSR);
/* Inform of status */
if (file != NULL) {
guac_client_log(client, GUAC_LOG_DEBUG,
"File \"%s\" opened",
fullpath);
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guac_protocol_send_ack(client->socket, stream, "SFTP: File opened", GUAC_PROTOCOL_STATUS_SUCCESS);
guac_socket_flush(client->socket);
}
else {
guac_client_log(client, GUAC_LOG_INFO, "Unable to open file \"%s\": %s",
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fullpath, libssh2_sftp_last_error(client_data->sftp_session));
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guac_protocol_send_ack(client->socket, stream, "SFTP: Open failed", GUAC_PROTOCOL_STATUS_RESOURCE_NOT_FOUND);
guac_socket_flush(client->socket);
}
/* Set handlers for file stream */
stream->blob_handler = guac_sftp_blob_handler;
stream->end_handler = guac_sftp_end_handler;
/* Store file within stream */
stream->data = file;
return 0;
}
int guac_sftp_blob_handler(guac_client* client, guac_stream* stream,
void* data, int length) {
/* Pull file from stream */
ssh_guac_client_data* client_data = (ssh_guac_client_data*) client->data;
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LIBSSH2_SFTP_HANDLE* file = (LIBSSH2_SFTP_HANDLE*) stream->data;
/* Attempt write */
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if (libssh2_sftp_write(file, data, length) == length) {
guac_client_log(client, GUAC_LOG_DEBUG, "%i bytes written", length);
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guac_protocol_send_ack(client->socket, stream, "SFTP: OK", GUAC_PROTOCOL_STATUS_SUCCESS);
guac_socket_flush(client->socket);
}
/* Inform of any errors */
else {
guac_client_log(client, GUAC_LOG_INFO, "Unable to write to file: %s",
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libssh2_sftp_last_error(client_data->sftp_session));
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guac_protocol_send_ack(client->socket, stream, "SFTP: Write failed", GUAC_PROTOCOL_STATUS_SERVER_ERROR);
guac_socket_flush(client->socket);
}
return 0;
}
int guac_sftp_end_handler(guac_client* client, guac_stream* stream) {
/* Pull file from stream */
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LIBSSH2_SFTP_HANDLE* file = (LIBSSH2_SFTP_HANDLE*) stream->data;
/* Attempt to close file */
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if (libssh2_sftp_close(file) == 0) {
guac_client_log(client, GUAC_LOG_DEBUG, "File closed");
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guac_protocol_send_ack(client->socket, stream, "SFTP: OK", GUAC_PROTOCOL_STATUS_SUCCESS);
guac_socket_flush(client->socket);
}
else {
guac_client_log(client, GUAC_LOG_INFO, "Unable to close file");
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guac_protocol_send_ack(client->socket, stream, "SFTP: Close failed", GUAC_PROTOCOL_STATUS_SERVER_ERROR);
guac_socket_flush(client->socket);
}
return 0;
}
int guac_sftp_ack_handler(guac_client* client, guac_stream* stream,
char* message, guac_protocol_status status) {
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ssh_guac_client_data* client_data = (ssh_guac_client_data*) client->data;
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LIBSSH2_SFTP_HANDLE* file = (LIBSSH2_SFTP_HANDLE*) stream->data;
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/* If successful, read data */
if (status == GUAC_PROTOCOL_STATUS_SUCCESS) {
/* Attempt read into buffer */
char buffer[4096];
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int bytes_read = libssh2_sftp_read(file, buffer, sizeof(buffer));
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/* If bytes read, send as blob */
if (bytes_read > 0) {
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guac_protocol_send_blob(client->socket, stream,
buffer, bytes_read);
guac_client_log(client, GUAC_LOG_DEBUG, "%i bytes sent to client",
bytes_read);
}
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/* If EOF, send end */
else if (bytes_read == 0) {
guac_client_log(client, GUAC_LOG_DEBUG, "File sent");
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guac_protocol_send_end(client->socket, stream);
guac_client_free_stream(client, stream);
}
/* Otherwise, fail stream */
else {
guac_client_log(client, GUAC_LOG_INFO, "Error reading file: %s",
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libssh2_sftp_last_error(client_data->sftp_session));
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guac_protocol_send_end(client->socket, stream);
guac_client_free_stream(client, stream);
}
guac_socket_flush(client->socket);
}
/* Otherwise, return stream to client */
else
guac_client_free_stream(client, stream);
return 0;
}
guac_stream* guac_sftp_download_file(guac_client* client,
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char* filename) {
ssh_guac_client_data* client_data = (ssh_guac_client_data*) client->data;
guac_stream* stream;
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LIBSSH2_SFTP_HANDLE* file;
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/* Attempt to open file for reading */
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file = libssh2_sftp_open(client_data->sftp_session, filename,
LIBSSH2_FXF_READ, 0);
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if (file == NULL) {
guac_client_log(client, GUAC_LOG_INFO, "Unable to read file \"%s\": %s",
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filename,
libssh2_sftp_last_error(client_data->sftp_session));
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return NULL;
}
/* Allocate stream */
stream = guac_client_alloc_stream(client);
stream->ack_handler = guac_sftp_ack_handler;
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stream->data = file;
/* Send stream start, strip name */
filename = basename(filename);
guac_protocol_send_file(client->socket, stream,
"application/octet-stream", filename);
guac_socket_flush(client->socket);
guac_client_log(client, GUAC_LOG_DEBUG, "Sending file \"%s\"", filename);
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return stream;
}
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void guac_sftp_set_upload_path(guac_client* client, char* path) {
ssh_guac_client_data* client_data = (ssh_guac_client_data*) client->data;
int length = strnlen(path, GUAC_SFTP_MAX_PATH);
/* Ignore requests which exceed maximum-allowed path */
if (length > GUAC_SFTP_MAX_PATH) {
guac_client_log(client, GUAC_LOG_ERROR,
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"Submitted path exceeds limit of %i bytes",
GUAC_SFTP_MAX_PATH);
return;
}
/* Copy path */
memcpy(client_data->sftp_upload_path, path, length);
guac_client_log(client, GUAC_LOG_DEBUG, "Upload path set to \"%s\"", path);
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}
guac_object* guac_sftp_expose_filesystem(guac_client* client) {
/* Init filesystem */
guac_object* filesystem = guac_client_alloc_object(client);
filesystem->get_handler = guac_sftp_get_handler;
filesystem->put_handler = guac_sftp_put_handler;
/* Send filesystem to client */
guac_protocol_send_filesystem(client->socket, filesystem, "/");
guac_socket_flush(client->socket);
/* Return allocated filesystem */
return filesystem;
}
/**
* Given a stream, the client to which it belongs, and the current directory
* list state, flushes the contents of the JSON buffer to a blob instruction.
* Note that this will flush the JSON buffer only, and will not necessarily
* flush the underlying guac_socket of the client.
*
* @param client
* The client to which the data will be flushed.
*
* @param stream
* The stream through which the flushed data should be sent as a blob.
*
* @param list_state
* The directory list state.
*/
static void guac_sftp_ls_flush_json(guac_client* client, guac_stream* stream,
guac_sftp_ls_state* list_state) {
/* If JSON buffer is non-empty, write contents to blob and reset */
if (list_state->json_size > 0) {
guac_protocol_send_blob(client->socket, stream,
list_state->json_buffer, list_state->json_size);
/* Reset JSON buffer size */
list_state->json_size = 0;
}
}
/**
* Given a stream, the client to which it belongs, and the current directory
* list state, writes the contents of the given buffer to the JSON buffer of
* the directory list state, flushing as necessary.
*
* @param client
* The client to which the data will be flushed as necessary.
*
* @param stream
* The stream through which the flushed data should be sent as a blob, if
* data must be flushed at all.
*
* @param list_state
* The directory list state containing the JSON buffer to which the given
* buffer should be written.
*
* @param buffer
* The buffer to write.
*
* @param length
* The number of bytes in the buffer.
*
* @return
* true if at least one blob was written, false otherwise.
*/
static bool guac_sftp_ls_write_json(guac_client* client, guac_stream* stream,
guac_sftp_ls_state* list_state, const char* buffer, int length) {
bool blob_written = false;
/*
* Append to and flush the JSON buffer as necessary to write the given
* data
*/
while (length > 0) {
/* Ensure provided data does not exceed size of buffer */
int blob_length = length;
if (blob_length > sizeof(list_state->json_buffer))
blob_length = sizeof(list_state->json_buffer);
/* Flush if more room is needed */
if (list_state->json_size + blob_length > sizeof(list_state->json_buffer)) {
guac_sftp_ls_flush_json(client, stream, list_state);
blob_written = true;
}
/* Append data to JSON buffer */
memcpy(list_state->json_buffer + list_state->json_size,
buffer, blob_length);
list_state->json_size += blob_length;
/* Advance to next blob of data */
buffer += blob_length;
length -= blob_length;
}
return blob_written;
}
/**
* Given a stream, the client to which it belongs, and the current directory
* list state, writes the given string as a proper JSON string, including
* starting and ending quotes. The contents of the string will be escaped as
* necessary.
*
* @param client
* The client to which the data will be flushed as necessary.
*
* @param stream
* The stream through which the flushed data should be sent as a blob, if
* data must be flushed at all.
*
* @param list_state
* The directory list state containing the JSON buffer to which the given
* string should be written as a proper JSON string.
*
* @param str
* The string to write.
*
* @return
* true if at least one blob was written, false otherwise.
*/
static bool guac_sftp_ls_write_json_string(guac_client* client,
guac_stream* stream, guac_sftp_ls_state* list_state,
const char* str) {
bool blob_written = false;
/* Write starting quote */
blob_written |= guac_sftp_ls_write_json(client, stream,
list_state, "\"", 1);
/* Write given string, escaping as necessary */
const char* current = str;
for (; *current != '\0'; current++) {
/* Escape all quotes */
if (*current == '"') {
/* Write any string content up to current character */
if (current != str)
blob_written |= guac_sftp_ls_write_json(client, stream,
list_state, str, current - str);
/* Escape the quote that was just read */
blob_written |= guac_sftp_ls_write_json(client, stream,
list_state, "\\", 1);
/* Reset string */
str = current;
}
}
/* Write any remaining string content */
if (current != str)
blob_written |= guac_sftp_ls_write_json(client, stream,
list_state, str, current - str);
/* Write ending quote */
blob_written |= guac_sftp_ls_write_json(client, stream,
list_state, "\"", 1);
return blob_written;
}
/**
* Given a stream, the client to which it belongs, and the current directory
* list state, writes the given directory entry as a JSON name/value pair. The
* name and value will be written as proper JSON strings separated by a colon.
*
* @param client
* The client to which the data will be flushed as necessary.
*
* @param stream
* The stream through which the flushed data should be sent as a blob, if
* data must be flushed at all.
*
* @param list_state
* The directory list state containing the JSON buffer to which the given
* directory should be written as a JSON name/value pair.
*
* @param mimetype
* The mimetype of the directory entry to write.
*
* @param filename
* The filename of the directory entry to write.
*
* @return
* true if at least one blob was written, false otherwise.
*/
static bool guac_sftp_ls_write_entry(guac_client* client, guac_stream* stream,
guac_sftp_ls_state* list_state, const char* mimetype,
const char* filename) {
bool blob_written = false;
/* Write leading comma if not first entry */
if (list_state->entries_written != 0)
blob_written |= guac_sftp_ls_write_json(client, stream,
list_state, ",", 1);
/* Write filename */
blob_written |= guac_sftp_ls_write_json_string(client, stream,
list_state, filename);
/* Separate filename from mimetype with colon */
blob_written |= guac_sftp_ls_write_json(client, stream,
list_state, ":", 1);
/* Write mimetype */
blob_written |= guac_sftp_ls_write_json_string(client, stream,
list_state, mimetype);
list_state->entries_written++;
return blob_written;
}
int guac_sftp_ls_ack_handler(guac_client* client, guac_stream* stream,
char* message, guac_protocol_status status) {
int bytes_read;
bool blob_written = false;
char filename[GUAC_SFTP_MAX_PATH];
LIBSSH2_SFTP_ATTRIBUTES attributes;
ssh_guac_client_data* client_data = (ssh_guac_client_data*) client->data;
LIBSSH2_SFTP* sftp = client_data->sftp_session;
guac_sftp_ls_state* list_state = (guac_sftp_ls_state*) stream->data;
/* If unsuccessful, free stream and abort */
if (status != GUAC_PROTOCOL_STATUS_SUCCESS) {
libssh2_sftp_closedir(list_state->directory);
guac_client_free_stream(client, stream);
free(list_state);
return 0;
}
/* While directory entries remain */
while ((bytes_read = libssh2_sftp_readdir(list_state->directory,
filename, sizeof(filename), &attributes)) > 0
&& !blob_written) {
char absolute_path[GUAC_SFTP_MAX_PATH];
/* Skip current and parent directory entries */
if (strcmp(filename, ".") == 0 || strcmp(filename, "..") == 0)
continue;
/* Concatenate into absolute path - skip if invalid */
if (!guac_ssh_append_filename(absolute_path,
list_state->directory_name, filename)) {
guac_client_log(client, GUAC_LOG_DEBUG,
"Skipping filename \"%s\" - filename is invalid or "
"resulting path is too long", filename);
continue;
}
/* Stat explicitly if symbolic link (might point to directory) */
if (LIBSSH2_SFTP_S_ISLNK(attributes.permissions))
libssh2_sftp_stat(sftp, absolute_path, &attributes);
/* Determine mimetype */
const char* mimetype;
if (LIBSSH2_SFTP_S_ISDIR(attributes.permissions))
mimetype = GUAC_CLIENT_STREAM_INDEX_MIMETYPE;
else
mimetype = "application/octet-stream";
/* Write leading brace if just starting */
if (list_state->entries_written == 0)
blob_written |= guac_sftp_ls_write_json(client, stream,
list_state, "{", 1);
/* Write entry */
blob_written |= guac_sftp_ls_write_entry(client, stream,
list_state, mimetype, absolute_path);
}
/* Complete JSON and cleanup at end of directory */
if (bytes_read <= 0) {
/* Write end of JSON */
guac_sftp_ls_write_json(client, stream, list_state, "}", 1);
guac_sftp_ls_flush_json(client, stream, list_state);
/* Clean up resources */
libssh2_sftp_closedir(list_state->directory);
free(list_state);
/* Signal of stream */
guac_protocol_send_end(client->socket, stream);
guac_client_free_stream(client, stream);
}
guac_socket_flush(client->socket);
return 0;
}
int guac_sftp_get_handler(guac_client* client, guac_object* object,
char* name) {
ssh_guac_client_data* client_data = (ssh_guac_client_data*) client->data;
LIBSSH2_SFTP* sftp = client_data->sftp_session;
LIBSSH2_SFTP_ATTRIBUTES attributes;
/* Attempt to read file information */
if (libssh2_sftp_stat(sftp, name, &attributes)) {
guac_client_log(client, GUAC_LOG_INFO, "Unable to read file \"%s\"",
name);
return 0;
}
/* If directory, send contents of directory */
if (LIBSSH2_SFTP_S_ISDIR(attributes.permissions)) {
/* Open as directory */
LIBSSH2_SFTP_HANDLE* dir = libssh2_sftp_opendir(sftp, name);
if (dir == NULL) {
guac_client_log(client, GUAC_LOG_INFO,
"Unable to read directory \"%s\": %s",
name, libssh2_sftp_last_error(sftp));
return 0;
}
/* Init directory listing state */
guac_sftp_ls_state* list_state = malloc(sizeof(guac_sftp_ls_state));
list_state->directory = dir;
strncpy(list_state->directory_name, name,
sizeof(list_state->directory_name));
list_state->json_size = 0;
list_state->entries_written = 0;
/* Allocate stream for body */
guac_stream* stream = guac_client_alloc_stream(client);
stream->ack_handler = guac_sftp_ls_ack_handler;
stream->data = list_state;
/* Associate new stream with get request */
guac_protocol_send_body(client->socket, object, stream,
GUAC_CLIENT_STREAM_INDEX_MIMETYPE, name);
}
/* Otherwise, send file contents */
else {
/* Open as normal file */
LIBSSH2_SFTP_HANDLE* file = libssh2_sftp_open(sftp, name,
LIBSSH2_FXF_READ, 0);
if (file == NULL) {
guac_client_log(client, GUAC_LOG_INFO,
"Unable to read file \"%s\": %s",
name, libssh2_sftp_last_error(sftp));
return 0;
}
/* Allocate stream for body */
guac_stream* stream = guac_client_alloc_stream(client);
stream->ack_handler = guac_sftp_ack_handler;
stream->data = file;
/* Associate new stream with get request */
guac_protocol_send_body(client->socket, object, stream,
"application/octet-stream", name);
}
guac_socket_flush(client->socket);
return 0;
}
int guac_sftp_put_handler(guac_client* client, guac_object* object,
guac_stream* stream, char* mimetype, char* name) {
ssh_guac_client_data* client_data = (ssh_guac_client_data*) client->data;
LIBSSH2_SFTP* sftp = client_data->sftp_session;
/* Open file via SFTP */
LIBSSH2_SFTP_HANDLE* file = libssh2_sftp_open(sftp, name,
LIBSSH2_FXF_WRITE | LIBSSH2_FXF_CREAT | LIBSSH2_FXF_TRUNC,
S_IRUSR | S_IWUSR);
/* Acknowledge stream if successful */
if (file != NULL) {
guac_client_log(client, GUAC_LOG_DEBUG, "File \"%s\" opened", name);
guac_protocol_send_ack(client->socket, stream, "SFTP: File opened",
GUAC_PROTOCOL_STATUS_SUCCESS);
}
/* Abort on failure */
else {
guac_client_log(client, GUAC_LOG_INFO, "Unable to open file \"%s\": %s",
name, libssh2_sftp_last_error(sftp));
guac_protocol_send_ack(client->socket, stream, "SFTP: Open failed",
GUAC_PROTOCOL_STATUS_RESOURCE_NOT_FOUND);
}
/* Set handlers for file stream */
stream->blob_handler = guac_sftp_blob_handler;
stream->end_handler = guac_sftp_end_handler;
/* Store file within stream */
stream->data = file;
guac_socket_flush(client->socket);
return 0;
}