diff --git a/src/protocols/ssh/client.h b/src/protocols/ssh/client.h index 202bff66..596f72fd 100644 --- a/src/protocols/ssh/client.h +++ b/src/protocols/ssh/client.h @@ -33,6 +33,8 @@ #include #include +#include + #ifdef ENABLE_SSH_AGENT #include "ssh_agent.h" #endif @@ -128,7 +130,13 @@ typedef struct ssh_guac_client_data { LIBSSH2_SFTP* sftp_session; /** - * The path files will be sent to. + * The filesystem object exposed for the SFTP session. + */ + guac_object* filesystem; + + /** + * The path files will be sent to, if uploaded directly via a "file" + * instruction. */ char sftp_upload_path[GUAC_SFTP_MAX_PATH]; diff --git a/src/protocols/ssh/sftp.c b/src/protocols/ssh/sftp.c index f52312fb..4819f432 100644 --- a/src/protocols/ssh/sftp.c +++ b/src/protocols/ssh/sftp.c @@ -28,10 +28,13 @@ #include #include #include +#include +#include #include #include #include +#include #include #include #include @@ -129,7 +132,7 @@ int guac_sftp_file_handler(guac_client* client, guac_stream* stream, client_data->sftp_upload_path, filename)) { guac_client_log(client, GUAC_LOG_DEBUG, - "Filename \"%s/%s\" is invalid or resulting path is too long", + "Filename \"%s\" is invalid or resulting path is too long", filename); /* Abort transfer - invalid filename */ @@ -321,3 +324,406 @@ void guac_sftp_set_upload_path(guac_client* client, char* path) { } +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) { + + /* STUB */ + guac_client_log(client, GUAC_LOG_DEBUG, "STUB: put: %s", name); + + return 0; +} + diff --git a/src/protocols/ssh/sftp.h b/src/protocols/ssh/sftp.h index 0564bf2d..b9e406e7 100644 --- a/src/protocols/ssh/sftp.h +++ b/src/protocols/ssh/sftp.h @@ -26,7 +26,11 @@ #include "config.h" +#include +#include + #include +#include #include #include @@ -35,6 +39,41 @@ */ #define GUAC_SFTP_MAX_PATH 2048 +/** + * The current state of a directory listing operation. + */ +typedef struct guac_sftp_ls_state { + + /** + * Reference to the directory currently being listed over SFTP. This + * directory must already be open from a call to libssh2_sftp_opendir(). + */ + LIBSSH2_SFTP_HANDLE* directory; + + /** + * The absolute path of the directory being listed. + */ + char directory_name[GUAC_SFTP_MAX_PATH]; + + /** + * Buffer of partial JSON data. The individual blobs which make up the JSON + * body of the directory listing sent over the Guacamole protocol will be + * built here. + */ + char json_buffer[4096]; + + /** + * The number of bytes currently used within the JSON buffer. + */ + int json_size; + + /** + * The number of entries written to the JSON thus far. + */ + int entries_written; + +} guac_sftp_ls_state; + /** * Handler for file messages which begins an SFTP data transfer (upload). */ @@ -68,5 +107,88 @@ guac_stream* guac_sftp_download_file(guac_client* client, char* filename); */ void guac_sftp_set_upload_path(guac_client* client, char* path); +/** + * Exposes access to SFTP via a filesystem object, returning that object. + * + * @param client + * The Guacamole client to expose the filesystem to. + * + * @return + * The resulting Guacamole filesystem object, initialized and exposed to + * the client. + */ +guac_object* guac_sftp_expose_filesystem(guac_client* client); + +/** + * Handler for get messages. In context of SFTP and the filesystem exposed via + * the Guacamole protocol, get messages request the body of a file within the + * filesystem. + * + * @param client + * The client receiving the get message. + * + * @param object + * The Guacamole protocol object associated with the get request itself. + * + * @param name + * The name of the input stream (file) being requested. + * + * @return + * Zero on success, non-zero on error. + */ +int guac_sftp_get_handler(guac_client* client, guac_object* object, + char* name); + +/** + * Handler for put messages. In context of SFTP and the filesystem exposed via + * the Guacamole protocol, put messages request write access to a file within + * the filesystem. + * + * @param client + * The client receiving the put message. + * + * @param object + * The Guacamole protocol object associated with the put request itself. + * + * @param stream + * The Guacamole protocol stream along which the client will be sending + * file data. + * + * @param mimetype + * The mimetype of the data being send along the stream. + * + * @param name + * The name of the input stream (file) being requested. + * + * @return + * Zero on success, non-zero on error. + */ +int guac_sftp_put_handler(guac_client* client, guac_object* object, + guac_stream* stream, char* mimetype, char* name); + +/** + * Handler for ack messages received due to receipt of a "body" or "blob" + * instruction associated with a SFTP directory list operation. + * + * @param client + * The client receiving the ack message. + * + * @param stream + * The Guacamole protocol stream associated with the received ack message. + * + * @param message + * An arbitrary human-readable message describing the nature of the + * success or failure denoted by this ack message. + * + * @param status + * The status code associated with this ack message, which may indicate + * success or an error. + * + * @return + * Zero on success, non-zero on error. + */ +int guac_sftp_ls_ack_handler(guac_client* client, guac_stream* stream, + char* message, guac_protocol_status status); + #endif diff --git a/src/protocols/ssh/ssh_client.c b/src/protocols/ssh/ssh_client.c index 7f60f781..b1afbf34 100644 --- a/src/protocols/ssh/ssh_client.c +++ b/src/protocols/ssh/ssh_client.c @@ -476,6 +476,9 @@ void* ssh_client_thread(void* data) { /* Set file handler */ client->file_handler = guac_sftp_file_handler; + /* Expose filesystem */ + guac_sftp_expose_filesystem(client); + guac_client_log(client, GUAC_LOG_DEBUG, "SFTP session initialized"); }