/* Kermit 95 SSH Subsystem * Copyright (C) 2022, David Goodwin * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * + Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * + Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in * the documentation and/or other materials provided with the * distribution. * + Neither the name of Columbia University nor the names of any * contributors may be used to endorse or promote products derived * from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ #ifndef CKWIN_SSHSUBSYS_H #define CKWIN_SSHSUBSYS_H #include #include "ckorbf.h" /* * On x86 and x86-64 Windows, four libssh backend DLLs are built currently: * G Vista+, GSSAPI k95sshg.dll * X XP k95sshx.dll * GX XP, GSSAPI k95sshgx.dll * STD Vista+ k95ssh.dll * Only the G and GX builds get GSSAPI support, and only the G and STD * builds get Agent support. */ #ifdef CKF_SSHDLL_VARIANT_G /* Vista+, GSSAPI : the only varaint to get all features */ #endif #ifdef CKF_SSHDLL_VARIANT_X /* Windows XP */ #define NO_SSH_AGENT_SUPPORT #define NO_SSH_GSSAPI_SUPPORT #endif #ifdef CKF_SSHDLL_VARIANT_GX /* Windows XP, GSSAPI */ #define NO_SSH_AGENT_SUPPORT #endif #ifdef CKF_SSHDLL_VARIANT_STD /* Vista+ */ #define NO_SSH_GSSAPI_SUPPORT #endif /* * Unless we're told not to, build with SSH Agent and GSSAPI Support. There * is no real harm in doing this - worst case there are some options in the * UI that don't work if the Windows version is too old or the libssh dll * lacks GSSAPI support. */ #ifndef NO_SSH_AGENT_SUPPORT #define SSH_AGENT_SUPPORT #endif #ifndef NO_SSH_GSSAPI_SUPPORT #define SSH_GSSAPI_SUPPORT #endif #ifdef SSH_DLL #undef debug #define debug(a,b,c,d) \ ((void)(debug_logging()?dodebug(a,b,(char *)(c),(CK_OFF_T)(d)):0)) #endif /* SSH_DLL */ #define SESSION_TYPE_PTY 0 #define SESSION_TYPE_COMMAND 1 #define SESSION_TYPE_SUBSYSTEM 2 /* Settings that can't be set */ #define SSH_MAX_PASSWORD_PROMPTS 3 /* Number of times you can retry password auth */ /* Errors we can return */ /* TODO: Confirm which of these are still used */ #define SSH_ERR_NO_ERROR 0 /* Everything is OK */ #define SSH_ERR_OK SSH_ERR_NO_ERROR #define SSH_ERR_TIMEOUT -1 /* -1 is a timeout for some K95 functions */ #define SSH_ERR_NEW_SESSION_FAILED -2 /* Failed to create new SSH session */ #define SSH_ERR_HOST_NOT_SPECIFIED -3 /* Hostname was null */ #define SSH_ERR_SSH_ERROR -4 /* Libssh error, call ssh_get_error(session) */ #define SSH_ERR_HOST_VERIFICATION_FAILED -5 /* Verification of remote host failed */ #define SSH_ERR_AUTH_ERROR -6 /* Serious auth error */ #define SSH_ERR_EOF -7 /* Remote has sent EOF */ #define SSH_ERR_CHANNEL_CLOSED -8 /* Channel is closed */ #define SSH_ERR_WAIT_FAILED -9 /* Failed to wait in SSH thread */ #define SSH_ERR_USER_CANCELED -10 /* User canceled */ /* -11 : not used */ #define SSH_ERR_UNSUPPORTED_VERSION -12 /* Unsupported SSH version */ /* -13 : not used */ #define SSH_ERR_NOT_IMPLEMENTED -14 /* Feature not implemented yet */ #define SSH_ERR_ACCESS_DENIED -15 /* Login failed */ /* -16 : not used */ #define SSH_ERR_STATE_MALLOC_FAILED -17 /* Failed to create ssh client state struct */ /* -18 : not used */ #define SSH_ERR_NO_INSTANCE -19 /* No current SSH Client instance */ #define SSH_ERR_MALLOC_FAILED -20 /* Failed to malloc something */ #define SSH_ERR_ZOMBIE_THREAD -21 /* SSH thread survived disconnect request */ #define SSH_ERR_DISCONNECT_FAILED -22 /* Failed to signal disconnect event */ #define SSH_ERR_EVENT_SIGNAL_FAILED -23 /* Failed to signal some event */ #define SSH_ERR_BUFFER_CONSUME_FAILED -24 /* Failed to consume processed data from a ring buffer */ #define SSH_ERR_BUFFER_WRITE_FAILED -25 /* Writing to a buffer failed, data has been lost */ #define SSH_ERR_THREAD_STATE_UNKNOWN -26 /* SSH thread failed to start or fail in a reasonable time. State is now unknown */ #define SSH_ERR_LISTEN_SOCKET_CREATE_FAILED -27 /* Failed to create listen socket for direct forward */ #define SSH_ERR_DIRECTFWD_GETADDRINFO_FAILED -28 /* Call to getaddrinfo failed while setting up direct forward server */ #define SSH_ERR_DIRECTFWD_BIND_FAILED -29 /* Call to bind failed while setting up direct forward server */ #define SSH_ERR_DIRECTFWD_LISTEN_FAILED -30 /* Call to listen failed while setting up direct forward server */ #define SSH_ERR_MUTEX_TIMEOUT -31 /* Timeout waiting for mutext */ #define SSH_ERR_UNSPECIFIED -32 /* Unspecified error */ #ifndef SSH_PF_T #define SSH_PF_T /* Copied from ckossh.h */ #define SSH_PORT_FORWARD_NULL 0 #define SSH_PORT_FORWARD_LOCAL 1 #define SSH_PORT_FORWARD_REMOTE 2 #define SSH_PORT_FORWARD_INVALID 99 /* Invalid entry / free for re-use */ typedef struct ssh_port_forward { /* Type of port forward. One of: * SSH_PORT_FORWARD_LOCAL Local (Direct) port forward * SSH_PORT_FORWARD_REMOTE Remote (Reverse) port forward * SSH_PORT_FORWARD_INVALID Empty list entry. Can be overwritten with a * new entry. Should otherwise be skipped over * SSH_PORT_FORWARD_NULL End of list marker * */ int type; /* For remote (reverse) forwards: address on the server to bind to. * Use NULL to bind ot all addresses. * * For local (direct) forwards: the address/host name for the servers * logs. * */ char* address; /* This is the port that listens for new connections. Its either on the * local host (Local/Direct forwarding) or the remote host (Remote/Reverse * forwarding. * * For Remote/Reverse forwarding, you can set this to 0 to allow the server * to choose the port. * */ int port; /* This is the host and port that connections will be made to when * something makes a connection to port 1. For Local (Direct) forwarding, * it's something accessible to the remote host, and for Remote (Reverse) * forwarding it's something accessible to the local host. */ char* hostname; int host_port; } ssh_port_forward_t; #endif /* SSH_PF_T */ #define MAX_AUTH_METHODS 10 #define MAX_ENVIRONMENT_VARIABLES 10 /** Parameters passed to the SSH thread on startup telling it what to connect * to, settings, etc. */ typedef struct { char* hostname; /* ssh_hst */ char* port; /* ssh_prt - port or service */ int log_verbosity; /* ssh_vrb, Verbosity 1-7 */ int session_type; /* 0=pty, 1=command, 2=subsys */ char* command_or_subsystem; /* ssh_cmd */ BOOL gssapi_delegate_credentials; /* ssh_gsd */ BOOL compression; /* ssh_cmp */ BOOL use_openssh_config; /* ssh_cfg */ int host_key_checking_mode; /* ssh_shk */ char* user_known_hosts_file; /* ssh2_unh */ char* global_known_hosts_file; /* ssh2_gnh */ char* username; /* uidbuf */ char* password; /* pwbuf if pwflg */ int pty_height, pty_width; /* Terminal dimensions */ char* terminal_type; /* Terminal type */ char* allowed_ciphers; /* Comma separated list of * allowed ciphers */ char* allowed_hostkey_algorithms; /* Comma separated list */ char* macs; /* Comma separated list */ char* key_exchange_methods; /* Comma separated list */ int keepalive_seconds; /* Keepalive interval in * seconds, 0 disables. */ int nodelay; /* Set to disable nagles agorithm */ char* proxy_command; /* Command to execute to connect to the server */ char* ssh_dir; /* SSH Directory */ const char** identity_files; /* SSH Identity Files */ SOCKET existing_socket; /* Connect with an existing socket */ char* agent_location; /* SSH Agent Location */ int agent_forwarding; /* Enable agent forwarding */ /* Which authentication methods should be attempted and their order. */ int authentication_methods[MAX_AUTH_METHODS]; /* Host verification may need to force password authentication off * if it detects something suspicious. Easier to set a flag than * go through authentication_methods removing all occurrences of * the password auth option. */ BOOL allow_password_auth; const ssh_port_forward_t *port_forwards; /* Environment variables */ char* environment_variables[MAX_ENVIRONMENT_VARIABLES][2]; BOOL forward_x; /* Forward X11 ? */ char* x11_host; /* Host where the X server is running */ int x11_display; /* X11 display number */ char* xauth_location; /* Xauth location (filename) */ } ssh_parameters_t; /** This is how the outside world communicates with the SSH thread */ typedef struct { /* These ring buffers have their own mutexes which you can acquire and * release with ring_buffer_lock() and ring_buffer_unlock(). */ ring_buffer_handle_t outputBuffer; ring_buffer_handle_t inputBuffer; /* Events raised by C-Kermit to signal conditions to the SSH thread */ HANDLE disconnectEvent; /* Disconnect requested by C-Kermit */ HANDLE ptySizeChangedEvent; /* K95 Terminal size changed. Store new values * in pty_height and pty_width */ HANDLE flushEvent; /* Flush requested by C-Kermit */ HANDLE breakEvent; /* Send break requested by C-Kermit */ HANDLE dataArrivedEvent; /* K95 has put data in the input buffer to be sent */ /* K95 has consumed data from the output buffer. Only raised when the * output buffer transitions from full to less than full in case the * network has more data waiting but couldn't do anything with it because of * a full buffer */ HANDLE dataConsumedEvent; /* Events raised by the SSH thread */ HANDLE clientStarted; HANDLE clientStopped; /* Everything else here is guarded by a single mutex (which you can ignore * if the thread is not running) */ HANDLE mutex; int error; /* SSH thread puts error codes here */ char* error_message; /* An error message, if any */ int pty_height, pty_width; /* For sending terminal size changes to the SSH thread */ HANDLE forwards_mutex; /* Guards the list of ssh_forward_t */ struct ssh_forward *forwards; /* Linked list of SSH forwarding config */ HANDLE forwardingConfigChanged; } ssh_client_t; /** Gets the current terminal (VTERM) dimensions * * @param rows Out - number of rows (lines) * @param cols Out - number of columns (chars) */ void get_current_terminal_dimensions(int* rows, int* cols); /** Constructs and populates a new ssh_parameters_t. * * @param hostname Hostname to connect to * @param port Port or service name * @param verbosity Logging verbosity level (0-7) * @param command Command or subsystem to execute * @param subsystem If command is a subsystem name rather than a command to * execute * @param compression If compression should be used in both directions or not * @param use_openssh_config If the OpenSSH client configuration file should * be read (if it exists) * @param gssapi_delegate_credentials GSSAPI Delegate Credentials * @param host_key_checking_mode Strict Host Key Checking Mode * @param user_known_hosts_file Pathname for user known hosts file * @param global_known_hosts_file Pathname for global known hosts file * @param username Username * @param password Password * @param terminal_type Terminal emulation type * @param pty_width Current terminal width * @param pty_height Current terminal height * @param auth_methods Comma-separated list of allowed authentication methods * @param ciphers Comma-separated list of allowed ciphers * @param heartbeat Heartbeat interval in seconds * @param hostkey_algorithms Comma-separated list of allowed hostkey algorithms * @param macs Comma-separated list of allowed macs * @param key_exchange_methods Comma-separated list of key exchange methods * @param nodelay Set to disable Nagle's algorithm * @param proxy_command Set the command to be executed in order to connect to server * @param forward_x Forward X11 * @param display_host Host running the X11 server * @param display_number X11 display number * @param xauth_location Xauth location * @param ssh_dir SSH Directory * @param identity_files List of identity files * @param socket Existing socket to use for the connection * @param agent_location SSH agent location * @param agent_forwarding Enable agent forwarding * @param environment_variables Environment variables to send * @return A new ssh_parameters_t instance. */ ssh_parameters_t* ssh_parameters_new( const char* hostname, char* port, int verbosity, const char* command, BOOL subsystem, BOOL compression, BOOL use_openssh_config, BOOL gssapi_delegate_credentials, int host_key_checking_mode, const char* user_known_hosts_file, const char* global_known_hosts_file, const char* username, const char* password, const char* terminal_type, int pty_width, int pty_height, const char* auth_methods, const char* ciphers, int heartbeat, const char* hostkey_algorithms, const char* macs, const char* key_exchange_methods, int nodelay, const char* proxy_command, const ssh_port_forward_t *port_forwards, BOOL forward_x, const char* display_host, int display_number, const char* xauth_location, const char* ssh_dir, const char** identity_files, SOCKET socket, const char* agent_location, int agent_forwarding, const char* environment_variables[MAX_ENVIRONMENT_VARIABLES][2]); /** Frees the ssh_parameters_t struct and all its members. * * @param parameters Parameters struct to free */ void ssh_parameters_free(ssh_parameters_t* parameters); /** Creates a new ssh_client_t struct * * @return A new ssh_client_t struct */ ssh_client_t * ssh_client_new(); /** Frees a ssh_client_t struct and all its members * * @param client ssh_client_t struct to free. */ void ssh_client_free(ssh_client_t *client); /** Starts the SSH Subsystem. Blocks until the thread has started and either * connects successfully or encounters an error. * * @param parameters SSH Connection Parameters * @param ssh_client The SSH Client Interface * @param threadHandle Out - handle for the created thread * @return 0 on success or an error. */ int start_ssh_subsystem(ssh_parameters_t* parameters, ssh_client_t *ssh_client, HANDLE *threadHandle); /** Try to acquire a mutex. Release it with ReleaseMutex(mutex). * * @param mutex Mutex to try and acquire * @param msTimeout Timeout in milliseconds. Pass INFINITE for no timeout. * @return TRUE if the mutex was acquired or FALSE on timeout or error. */ BOOL acquire_mutex(HANDLE mutex, DWORD msTimeout); /** Libssh ssh_auth_callback implementation */ int auth_prompt(const char* prompt, char* buf, size_t len, int echo, int verify, void* userdata); #endif /* CKWIN_SSHSUBSYS_H */