Collaboration diagram for The SSH helper functions:

Functions
int	ssh_getpass (const char prompt, char buf, size_t len, int echo, int verify)
	Get a password from the console.

int	ssh_get_random (void *where, int len, int strong)
	Get random bytes.

char *	ssh_get_user_home_dir (void)

int	ssh_file_readaccess_ok (const char *file)

int	ssh_dir_writeable (const char *path)
	Check if the given path is an existing directory and that is accessible for writing.

char *	ssh_get_local_username (void)

int	ssh_is_ipaddr_v4 (const char *str)

int	ssh_is_ipaddr (const char *str)

char *	ssh_lowercase (const char *str)

char *	ssh_hostport (const char *host, int port)

char *	ssh_get_hexa (const unsigned char *what, size_t len)
	Convert a buffer into a colon separated hex string. The caller has to free the memory.

void	ssh_print_hexa (const char descr, const unsigned char what, size_t len)

void	ssh_log_hexdump (const char descr, const unsigned char what, size_t len)
	Log the content of a buffer in hexadecimal format, similar to the output of 'hexdump -C' command.

const char *	ssh_version (int req_version)
	Check if libssh is the required version or get the version string.

struct ssh_list *	ssh_list_new (void)

void	ssh_list_free (struct ssh_list *list)

struct ssh_iterator *	ssh_list_get_iterator (const struct ssh_list *list)

struct ssh_iterator *	ssh_list_find (const struct ssh_list list, void value)

size_t	ssh_list_count (const struct ssh_list *list)
	Get the number of elements in the list.

int	ssh_list_append (struct ssh_list list, const void data)

int	ssh_list_prepend (struct ssh_list list, const void data)

void	ssh_list_remove (struct ssh_list list, struct ssh_iterator iterator)

const void *	_ssh_list_pop_head (struct ssh_list *list)

char *	ssh_dirname (const char *path)
	Parse directory component.

char *	ssh_basename (const char *path)
	basename - parse filename component.

int	ssh_mkdir (const char *pathname, mode_t mode)
	Attempts to create a directory with the given pathname.

int	ssh_mkdirs (const char *pathname, mode_t mode)
	Attempts to create a directory with the given pathname. The missing directories in the given pathname are created recursively.

char *	ssh_path_expand_tilde (const char *d)
	Expand a directory starting with a tilde '~'.

char *	ssh_path_expand_escape (ssh_session session, const char *s)

int	ssh_analyze_banner (ssh_session session, int server)

void	ssh_timestamp_init (struct ssh_timestamp *ts)

int	ssh_make_milliseconds (unsigned long sec, unsigned long usec)

int	ssh_timeout_elapsed (struct ssh_timestamp *ts, int timeout)

int	ssh_timeout_update (struct ssh_timestamp *ts, int timeout)
	updates a timeout value so it reflects the remaining time

void	explicit_bzero (void *s, size_t n)

char *	strndup (const char *s, size_t n)

void	uint64_inc (unsigned char *counter)

int	ssh_quote_file_name (const char file_name, char buf, size_t buf_len)

int	ssh_newline_vis (const char string, char buf, size_t buf_len)

int	ssh_tmpname (char *name)

char *	ssh_strreplace (const char src, const char pattern, const char *replace)

char *	ssh_strerror (int err_num, char *buf, size_t buflen)

ssize_t	ssh_readn (int fd, void *buf, size_t nbytes)
	Read the requested number of bytes from a local file.

ssize_t	ssh_writen (int fd, const void *buf, size_t nbytes)
	Write the requested number of bytes to a local file.

int	ssh_check_hostname_syntax (const char *hostname)
	Checks syntax of a domain name.

int	ssh_check_username_syntax (const char *username)
	Checks syntax of a username.

void	ssh_proxyjumps_free (struct ssh_list *proxy_jump_list)
	Free proxy jump list.

bool	ssh_libssh_proxy_jumps (void)
	Check if libssh proxy jumps is enabled.

int	encode_current_tty_opts (unsigned char *buf, size_t buflen)
	Encode the current TTY options as SSH modes.

Detailed Description

Different helper functions used in the SSH Library.

Function Documentation

◆ encode_current_tty_opts()

int encode_current_tty_opts	(	unsigned char *	buf,
		size_t	buflen )

Encode the current TTY options as SSH modes.

Call this function to determine the settings of the process' TTY and encode them as SSH Terminal Modes according to RFC 4254 section 8.

If STDIN isn't connected to a TTY, this function fills the buffer with "sane" default modes.

The encoded modes can be passed to ssh_channel_request_pty_size_modes .

unsigned char modes_buf[SSH_TTY_MODES_MAX_BUFSIZE];

encode_current_tty_opts(modes_buf, sizeof(modes_buf));

encode_current_tty_opts

int encode_current_tty_opts(unsigned char *buf, size_t buflen)

Encode the current TTY options as SSH modes.

Definition ttyopts.c:431

Parameters

[out]	buf	Modes will be encoded into this buffer.
[in]	buflen	The length of the buffer.

Returns: number of bytes in the buffer on success, -1 on error.

◆ ssh_basename()

char * ssh_basename ( const char * path )

basename - parse filename component.

basename breaks a null-terminated pathname string into a filename component. ssh_basename() returns the component following the final '/'. Trailing '/' characters are not counted as part of the pathname.

Parameters

[in] path The path to parse.

Returns: The filename of path or NULL if we can't allocate memory. If path is the string "/", basename returns the string "/". If path is NULL or an empty string, "." is returned. The caller needs to free this memory ssh_string_free_char().

See also: ssh_string_free_char()

◆ ssh_check_hostname_syntax()

int ssh_check_hostname_syntax ( const char * hostname )

Checks syntax of a domain name.

The check is made based on the RFC1035 section 2.3.1 Allowed characters are: hyphen, period, digits (0-9) and letters (a-zA-Z)

The label should be no longer than 63 characters The label should start with a letter and end with a letter or number The label in this implementation can start with a number to allow virtual URLs to pass. Note that this will make IPv4 addresses to pass this check too.

Parameters

hostname The domain name to be checked, has to be null terminated

Returns: SSH_OK if the hostname passes syntax check SSH_ERROR otherwise or if hostname is NULL or empty string

◆ ssh_check_username_syntax()

int ssh_check_username_syntax ( const char * username )

Checks syntax of a username.

This check disallows metacharacters in the username

Parameters

username The username to be checked, has to be null terminated

Returns: SSH_OK if the username passes syntax check SSH_ERROR otherwise or if username is NULL or empty string

◆ ssh_dir_writeable()

int ssh_dir_writeable ( const char * path )

Check if the given path is an existing directory and that is accessible for writing.

Parameters

[in] path Path to the directory to be checked

Returns: Return 1 if the directory exists and is accessible; 0 otherwise

◆ ssh_dirname()

char * ssh_dirname ( const char * path )

Parse directory component.

dirname breaks a null-terminated pathname string into a directory component. In the usual case, ssh_dirname() returns the string up to, but not including, the final '/'. Trailing '/' characters are not counted as part of the pathname. The caller must free the memory using ssh_string_free_char().

Parameters

[in] path The path to parse.

Returns: The dirname of path or NULL if we can't allocate memory. If path does not contain a slash, c_dirname() returns the string ".". If path is a string "/", it returns the string "/". If path is NULL or an empty string, "." is returned. The memory needs to be freed using ssh_string_free_char().

See also: ssh_string_free_char()

◆ ssh_get_hexa()

char * ssh_get_hexa	(	const unsigned char *	what,
		size_t	len )

Convert a buffer into a colon separated hex string. The caller has to free the memory.

Parameters

[in]	what	What should be converted to a hex string.
[in]	len	Length of the buffer to convert.

Returns: The hex string or NULL on error. The memory needs to be freed using ssh_string_free_char().

See also: ssh_string_free_char()

◆ ssh_get_random()

int ssh_get_random	(	void *	where,
		int	len,
		int	strong )

Get random bytes.

Make sure to always check the return code of this function!

Parameters

[in]	where	The buffer to fill with random bytes
[in]	len	The size of the buffer to fill.
[in]	strong	Use a strong or private RNG source.

Returns: 1 on success, 0 on error.

◆ ssh_getpass()

int ssh_getpass	(	const char *	prompt,
		char *	buf,
		size_t	len,
		int	echo,
		int	verify )

Get a password from the console.

You should make sure that the buffer is an empty string!

You can also use this function to ask for a username. Then you can fill the buffer with the username and it is shows to the users. If the users just presses enter the buffer will be untouched.

char username[128];
 
snprintf(username, sizeof(username), "john");
 
ssh_getpass("Username:", username, sizeof(username), 1, 0);

The prompt will look like this:

Username: [john]

If you press enter then john is used as the username, or you can type it in to change it.

Parameters

[in]	prompt	The prompt to show to ask for the password.
[out]	buf	The buffer the password should be stored. It NEEDS to be empty or filled out.
[in]	len	The length of the buffer.
[in]	echo	Should we echo what you type.
[in]	verify	Should we ask for the password twice.

Returns: 0 on success, -1 on error.

◆ ssh_libssh_proxy_jumps()

bool ssh_libssh_proxy_jumps ( void )

Check if libssh proxy jumps is enabled.

If env variable OPENSSH_PROXYJUMP is set to 1 then proxyjump will be through the OpenSSH binary.

Returns: false if OPENSSH_PROXYJUMP=1 true otherwise

◆ ssh_list_count()

size_t ssh_list_count ( const struct ssh_list * list )

Get the number of elements in the list.

Parameters

[in] list The list to count.

Returns: The number of elements in the list.

◆ ssh_log_hexdump()

void ssh_log_hexdump	(	const char *	descr,
		const unsigned char *	what,
		size_t	len )

Log the content of a buffer in hexadecimal format, similar to the output of 'hexdump -C' command.

The first logged line is the given description followed by the length. Then the content of the buffer is logged 16 bytes per line in the following format:

(offset) (first 8 bytes) (last 8 bytes) (the 16 bytes as ASCII char values)

The output for a 16 bytes array containing values from 0x00 to 0x0f would be:

"Example (16 bytes):" " 00000000 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f ................"

The value for each byte as corresponding ASCII character is printed at the end if the value is printable. Otherwise, it is replaced with '.'.

Parameters

[in]	descr	A description for the content to be logged
[in]	what	The buffer to be logged
[in]	len	The length of the buffer given in what

Note: If a too long description is provided (which would result in a first line longer than 80 bytes), the function will fail.

◆ ssh_mkdir()

int ssh_mkdir	(	const char *	pathname,
		mode_t	mode )

Attempts to create a directory with the given pathname.

This is the portable version of mkdir, mode is ignored on Windows systems.

Parameters

[in]	pathname	The path name to create the directory.
[in]	mode	The permissions to use.

Returns: 0 on success, < 0 on error with errno set.

◆ ssh_mkdirs()

int ssh_mkdirs	(	const char *	pathname,
		mode_t	mode )

Attempts to create a directory with the given pathname. The missing directories in the given pathname are created recursively.

Parameters

[in]	pathname	The path name to create the directory.
[in]	mode	The permissions to use.

Returns: 0 on success, < 0 on error with errno set.

Note: mode is ignored on Windows systems.

◆ ssh_path_expand_tilde()

char * ssh_path_expand_tilde ( const char * d )

Expand a directory starting with a tilde '~'.

Parameters

[in] d The directory to expand.

Returns: The expanded directory, NULL on error. The caller needs to free the memory using ssh_string_free_char().

See also: ssh_string_free_char()

◆ ssh_print_hexa()

void ssh_print_hexa	(	const char *	descr,
		const unsigned char *	what,
		size_t	len )

Deprecated: Please use ssh_print_hash() instead

◆ ssh_proxyjumps_free()

void ssh_proxyjumps_free ( struct ssh_list * proxy_jump_list )

Free proxy jump list.

Frees everything in a proxy jump list, but doesn't free the ssh_list

Parameters

proxy_jump_list

◆ ssh_readn()

ssize_t ssh_readn	(	int	fd,
		void *	buf,
		size_t	nbytes )

Read the requested number of bytes from a local file.

A call to read() may perform a short read even when sufficient data is present in the file. This function can be used to avoid such short reads.

This function tries to read the requested number of bytes from the file until one of the following occurs :

Requested number of bytes are read.
EOF is encountered before reading the requested number of bytes.
An error occurs.

On encountering an error due to an interrupt, this function ignores that error and continues trying to read the data.

Parameters

[in]	fd	The file descriptor of the local file to read from.
[out]	buf	Pointer to a buffer in which read data will be stored.
[in]	nbytes	Number of bytes to read.

Returns: Number of bytes read on success, SSH_ERROR on error with errno set to indicate the error.

◆ ssh_timeout_update()

int ssh_timeout_update	(	struct ssh_timestamp *	ts,
		int	timeout )

updates a timeout value so it reflects the remaining time

Parameters

[in]	ts	pointer to an existing timestamp
[in]	timeout	timeout in milliseconds. Negative values mean infinite timeout

Returns: remaining time in milliseconds, 0 if elapsed, -1 if never.

◆ ssh_version()

const char * ssh_version ( int req_version )

Check if libssh is the required version or get the version string.

Parameters

[in] req_version The version required.

Returns: If the version of libssh is newer than the version required it will return a version string. NULL if the version is older.

Example:

if (ssh_version(SSH_VERSION_INT(0,2,1)) == NULL) {
  fprintf(stderr, "libssh version is too old!\n");
  exit(1);
}
 
if (debug) {
  printf("libssh %s\n", ssh_version(0));
}

◆ ssh_writen()

ssize_t ssh_writen	(	int	fd,
		const void *	buf,
		size_t	nbytes )

Write the requested number of bytes to a local file.

A call to write() may perform a short write on a local file. This function can be used to avoid short writes.

This function tries to write the requested number of bytes until those many bytes are written or some error occurs.

On encountering an error due to an interrupt, this function ignores that error and continues trying to write the data.

Parameters

[in]	fd	The file descriptor of the local file to write to.
[in]	buf	Pointer to a buffer in which data to write is stored.
[in]	nbytes	Number of bytes to write.

Returns: Number of bytes written on success, SSH_ERROR on error with errno set to indicate the error.

Functions

Detailed Description

Function Documentation

◆ encode_current_tty_opts()

◆ ssh_basename()

◆ ssh_check_hostname_syntax()

◆ ssh_check_username_syntax()

◆ ssh_dir_writeable()

◆ ssh_dirname()

◆ ssh_get_hexa()

◆ ssh_get_random()

◆ ssh_getpass()

◆ ssh_libssh_proxy_jumps()

◆ ssh_list_count()

◆ ssh_log_hexdump()

◆ ssh_mkdir()

◆ ssh_mkdirs()

◆ ssh_path_expand_tilde()

◆ ssh_print_hexa()

◆ ssh_proxyjumps_free()

◆ ssh_readn()

◆ ssh_timeout_update()

◆ ssh_version()

◆ ssh_writen()