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ZMQ_MSG_GETS(3)			  0MQ Manual		       ZMQ_MSG_GETS(3)

NAME
       zmq_msg_gets - get message metadata property

SYNOPSIS
       const char *zmq_msg_gets	(zmq_msg_t *message, const char	*property);

DESCRIPTION
       The zmq_msg_gets() function shall return	the string value for the
       metadata	property specified by the property argument for	the message
       pointed to by the message argument. Both	the property argument and the
       value shall be NULL-terminated UTF8-encoded strings.

       Metadata	is defined on a	per-connection basis during the	ZeroMQ
       connection handshake as specified in <rfc.zeromq.org/spec:37>.
       Applications can	set metadata properties	using zmq_setsockopt(3)	option
       ZMQ_METADATA. Application metadata properties must be prefixed with X-.

       In addition to application metadata, the	following ZMTP properties can
       be retrieved with the zmq_msg_gets() function:

	   Socket-Type
	   Routing-Id

       Note: Identity is a deprecated alias for	Routing-Id.

       Additionally, when available for	the underlying transport, the
       Peer-Address property will return the IP	address	of the remote endpoint
       as returned by getnameinfo(2).

       The names of these properties are also defined in zmq.h as
       ZMQ_MSG_PROPERTY_SOCKET_TYPE ZMQ_MSG_PROPERTY_ROUTING_ID, and
       ZMQ_MSG_PROPERTY_PEER_ADDRESS. Currently, these definitions are only
       available as a DRAFT API.

       Other properties	may be defined based on	the underlying security
       mechanism, see ZAP authenticated	connection sample below.

RETURN VALUE
       The zmq_msg_gets() function shall return	the string value for the
       property	if successful. Otherwise it shall return NULL and set errno to
       one of the values defined below.	The caller shall not modify or free
       the returned value, which shall be owned	by the message.	The encoding
       of the property and value shall be UTF8.

ERRORS
       EINVAL
	   The requested property is unknown.

EXAMPLE
       Getting the ZAP authenticated user id for a message:.

	   zmq_msg_t msg;
	   zmq_msg_init	(&msg);
	   rc =	zmq_msg_recv (&msg, dealer, 0);
	   assert (rc != -1);
	   const char *user_id = zmq_msg_gets (&msg, ZMQ_MSG_PROPERTY_USER_ID);
	   zmq_msg_close (&msg);

SEE ALSO
       zmq(7) zmq_setsockopt(3)

AUTHORS
       This page was written by	the 0MQ	community. To make a change please
       read the	0MQ Contribution Policy	at
       http://www.zeromq.org/docs:contributing.

0MQ 4.3.4			  01/17/2021		       ZMQ_MSG_GETS(3)

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLE | SEE ALSO | AUTHORS

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