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- 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 linkzmq: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
- --------
- linkzmq:zmq[7]
- linkzmq: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>.
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