SSL/TLS specific functionality

These functions provide SSL/TLS specific functionality. More...

Typedefs
typedef int(*	xmpp_certfail_handler) (const xmpp_tlscert_t *cert, const char *const errormsg)
	The Handler function which will be called when the TLS stack can't verify the authenticity of a Certificate that gets presented by the server we're trying to connect to. More...
typedef int(*	xmpp_password_callback) (char *pw, size_t pw_max, xmpp_conn_t *conn, void *userdata)
	The Handler function which will be called when the TLS stack can't decrypt a password protected key file. More...

Enumerations
enum	xmpp_cert_element_t {   XMPP_CERT_VERSION , XMPP_CERT_SERIALNUMBER , XMPP_CERT_SUBJECT , XMPP_CERT_ISSUER ,   XMPP_CERT_NOTBEFORE , XMPP_CERT_NOTAFTER , XMPP_CERT_KEYALG , XMPP_CERT_SIGALG ,   XMPP_CERT_FINGERPRINT_SHA1 , XMPP_CERT_FINGERPRINT_SHA256 , XMPP_CERT_ELEMENT_MAX }
	Certificate Elements. More...

Functions
void	xmpp_conn_set_certfail_handler (xmpp_conn_t *const conn, xmpp_certfail_handler hndl)
	Set the Handler function which will be called when the TLS stack can't verify the CA of the server we're trying to connect to. More...
void	xmpp_conn_set_cafile (xmpp_conn_t *const conn, const char *path)
	Set the CAfile. More...
void	xmpp_conn_set_capath (xmpp_conn_t *const conn, const char *path)
	Set the CApath. More...
xmpp_tlscert_t *	xmpp_conn_get_peer_cert (xmpp_conn_t *const conn)
	Retrieve the peer certificate. More...
void	xmpp_conn_set_password_callback (xmpp_conn_t *conn, xmpp_password_callback cb, void *userdata)
	Set the Callback function which will be called when the TLS stack can't decrypt a password protected key file. More...
void	xmpp_conn_set_password_retries (xmpp_conn_t *conn, unsigned int retries)
	Set the number of retry attempts to decrypt a private key file. More...
const char *	xmpp_conn_get_keyfile (const xmpp_conn_t *conn)
	Retrieve the path of the key file that shall be unlocked. More...
void	xmpp_conn_set_client_cert (xmpp_conn_t *const conn, const char *const cert, const char *const key)
	Set the Client Certificate and Private Key or PKCS#12 encoded file that will be bound to the connection. More...
unsigned int	xmpp_conn_cert_xmppaddr_num (xmpp_conn_t *const conn)
	Get the number of xmppAddr entries in the client certificate. More...
char *	xmpp_conn_cert_xmppaddr (xmpp_conn_t *const conn, unsigned int n)
	Get a specific xmppAddr entry. More...
xmpp_ctx_t *	xmpp_tlscert_get_ctx (const xmpp_tlscert_t *cert)
	Get the Strophe context which is assigned to this certificate. More...
xmpp_conn_t *	xmpp_tlscert_get_conn (const xmpp_tlscert_t *cert)
	Get the Strophe connection which is assigned to this certificate. More...
const char *	xmpp_tlscert_get_pem (const xmpp_tlscert_t *cert)
	Get the complete PEM of this certificate. More...
const char *	xmpp_tlscert_get_dnsname (const xmpp_tlscert_t *cert, size_t n)
	Get the dnsName entries out of the SubjectAlternativeNames. More...
const char *	xmpp_tlscert_get_string (const xmpp_tlscert_t *cert, xmpp_cert_element_t elmnt)
	Get various parts of the certificate as String. More...
const char *	xmpp_tlscert_get_description (xmpp_cert_element_t elmnt)
	Get a descriptive string for each xmpp_cert_element_t. More...
void	xmpp_tlscert_free (xmpp_tlscert_t *cert)
	Free a certificate object. More...

Detailed Description

These functions provide SSL/TLS specific functionality.

Typedef Documentation

xmpp_certfail_handler

typedef int(* xmpp_certfail_handler) (const xmpp_tlscert_t *cert, const char *const errormsg)

The Handler function which will be called when the TLS stack can't verify the authenticity of a Certificate that gets presented by the server we're trying to connect to.

When this function is called and details of the cert have to be kept, please copy them yourself. The cert object will be free'd automatically when this function returns.

NB: errormsg is specific per certificate on OpenSSL and the same for all certificates on GnuTLS.

Parameters

cert	a Strophe certificate object
errormsg	The error that caused this.

Returns

0 if the connection attempt should be terminated, 1 if the connection should be established.

xmpp_password_callback

typedef int(* xmpp_password_callback) (char *pw, size_t pw_max, xmpp_conn_t *conn, void *userdata)

The Handler function which will be called when the TLS stack can't decrypt a password protected key file.

When this callback is called it shall write a NULL-terminated string of maximum length pw_max - 1 to pw.

This is currently only supported for GnuTLS and OpenSSL.

On 2022-02-02 the following maximum lengths are valid:

include/gnutls/pkcs11.h: #define GNUTLS_PKCS11_MAX_PIN_LEN 256
include/openssl/pem.h: #define PEM_BUFSIZE 1024

We expect the buffer to be NULL-terminated, therefore the usable lengths are:

• 255 for GnuTLS
• 1023 for OpenSSL

Useful API's inside this callback are e.g.

xmpp_conn_get_keyfile

Parameters

pw	The buffer where the password shall be stored.
pw_max	The maximum length of the password.
conn	The Strophe connection object this callback originates from.
userdata	The userdata pointer as supplied when setting this callback.

Returns

-1 on error, else the number of bytes written to pw w/o terminating NUL byte

Enumeration Type Documentation

xmpp_cert_element_t

enum xmpp_cert_element_t

Certificate Elements.

Enumerator
XMPP_CERT_VERSION	X.509 Version.
XMPP_CERT_SERIALNUMBER	SerialNumber.
XMPP_CERT_SUBJECT	Subject.
XMPP_CERT_ISSUER	Issuer.
XMPP_CERT_NOTBEFORE	Issued on.
XMPP_CERT_NOTAFTER	Expires on.
XMPP_CERT_KEYALG	Public Key Algorithm.
XMPP_CERT_SIGALG	Certificate Signature Algorithm.
XMPP_CERT_FINGERPRINT_SHA1	Fingerprint SHA-1.
XMPP_CERT_FINGERPRINT_SHA256	Fingerprint SHA-256.
XMPP_CERT_ELEMENT_MAX	Last element of the enum.

Function Documentation

xmpp_conn_set_certfail_handler()

void xmpp_conn_set_certfail_handler	(	xmpp_conn_t *const	conn,
		xmpp_certfail_handler	hndl
	)

Set the Handler function which will be called when the TLS stack can't verify the CA of the server we're trying to connect to.

Parameters

conn	a Strophe connection object
hndl	certfail Handler function

xmpp_conn_set_cafile()

void xmpp_conn_set_cafile	(	xmpp_conn_t *const	conn,
		const char *	path
	)

Set the CAfile.

Parameters

conn	a Strophe connection object
path	path to a certificate file

xmpp_conn_set_capath()

void xmpp_conn_set_capath	(	xmpp_conn_t *const	conn,
		const char *	path
	)

Set the CApath.

Parameters

conn	a Strophe connection object
path	path to a folder containing certificates

xmpp_conn_get_peer_cert()

xmpp_tlscert_t * xmpp_conn_get_peer_cert

(

xmpp_conn_t *const

conn

)

Retrieve the peer certificate.

The returned Certificate object must be free'd by calling xmpp_tlscert_free

Parameters

conn	a Strophe connection object

Returns

a Strophe Certificate object

xmpp_conn_set_password_callback()

void xmpp_conn_set_password_callback	(	xmpp_conn_t *	conn,
		xmpp_password_callback	cb,
		void *	userdata
	)

Set the Callback function which will be called when the TLS stack can't decrypt a password protected key file.

Parameters

conn	a Strophe connection object
cb	The callback function that shall be called
userdata	An opaque data pointer that will be passed to the callback

xmpp_conn_set_password_retries()

void xmpp_conn_set_password_retries	(	xmpp_conn_t *	conn,
		unsigned int	retries
	)

Set the number of retry attempts to decrypt a private key file.

In case the user enters the password manually it can be useful to directly retry if the decryption of the key file failed.

Parameters

conn	a Strophe connection object
retries	The number of retries that should be tried

xmpp_conn_get_keyfile()

const char * xmpp_conn_get_keyfile

(

const xmpp_conn_t *

conn

)

Retrieve the path of the key file that shall be unlocked.

This makes usually sense to be called from the xmpp_password_callback .

Parameters

conn	a Strophe connection object

Returns

a String of the path to the key file

xmpp_conn_set_client_cert()

void xmpp_conn_set_client_cert	(	xmpp_conn_t *const	conn,
		const char *const	cert,
		const char *const	key
	)

Set the Client Certificate and Private Key or PKCS#12 encoded file that will be bound to the connection.

If any of them was previously set, it will be discarded. This should not be used after a connection is created. The function will make a copy of the strings passed in.

In case the Private Key is encrypted, a callback must be set via xmpp_conn_set_password_callback so the TLS stack can retrieve the password.

In case one wants to use a PKCS#12 encoded file, it should be passed via the cert parameter and key should be NULL. Passing a PKCS#12 file in key is deprecated.

Parameters

conn	a Strophe connection object
cert	path to a certificate file or a P12 file
key	path to a private key file or a P12 file

xmpp_conn_cert_xmppaddr_num()

unsigned int xmpp_conn_cert_xmppaddr_num

(

xmpp_conn_t *const

conn

)

Get the number of xmppAddr entries in the client certificate.

Parameters

conn	a Strophe connection object

Returns

the number of xmppAddr entries in the client certificate

xmpp_conn_cert_xmppaddr()

char * xmpp_conn_cert_xmppaddr	(	xmpp_conn_t *const	conn,
		unsigned int	n
	)

Get a specific xmppAddr entry.

Parameters

conn	a Strophe connection object
n	the index of the entry, starting at 0

Returns

a string containing the xmppAddr or NULL if n is out of range

xmpp_tlscert_get_ctx()

xmpp_ctx_t * xmpp_tlscert_get_ctx

(

const xmpp_tlscert_t *

cert

)

Get the Strophe context which is assigned to this certificate.

Parameters

cert	a Strophe TLS certificate object

Returns

the Strophe context object where this certificate originates from

xmpp_tlscert_get_conn()

xmpp_conn_t * xmpp_tlscert_get_conn

(

const xmpp_tlscert_t *

cert

)

Get the Strophe connection which is assigned to this certificate.

Parameters

cert	a Strophe TLS certificate object

Returns

the Strophe connection object where this certificate originates from

xmpp_tlscert_get_pem()

const char * xmpp_tlscert_get_pem

(

const xmpp_tlscert_t *

cert

)

Get the complete PEM of this certificate.

Parameters

cert	a Strophe TLS certificate object

Returns

a string containing the PEM of this certificate

xmpp_tlscert_get_dnsname()

const char * xmpp_tlscert_get_dnsname	(	const xmpp_tlscert_t *	cert,
		size_t	n
	)

Get the dnsName entries out of the SubjectAlternativeNames.

Note: Max. MAX_NUM_DNSNAMES are supported.

Parameters

cert	a Strophe TLS certificate object
n	which dnsName entry

Returns

a string with the n'th dnsName

xmpp_tlscert_get_string()

const char * xmpp_tlscert_get_string	(	const xmpp_tlscert_t *	cert,
		xmpp_cert_element_t	elmnt
	)

Get various parts of the certificate as String.

c.f. xmpp_cert_element_t for details.

Parameters

cert	a Strophe TLS certificate object
elmnt	which part of the certificate

Returns

a string with the part of the certificate

xmpp_tlscert_get_description()

const char * xmpp_tlscert_get_description

(

xmpp_cert_element_t

elmnt

)

Get a descriptive string for each xmpp_cert_element_t.

c.f. xmpp_cert_element_t for details.

Parameters

elmnt

which element

Returns

a string with the description

xmpp_tlscert_free()

void xmpp_tlscert_free

(

xmpp_tlscert_t *

cert

)

Free a certificate object.

Parameters

cert	a Strophe TLS certificate object