ZMQ_GETSOCKOPT(3) 0MQ Manual ZMQ_GETSOCKOPT(3)
NAME
zmq_getsockopt - get 0MQ socket options
SYNOPSIS
int zmq_getsockopt (void *socket, int option_name, void *option_value,
size_t *option_len);
DESCRIPTION
The zmq_getsockopt() function shall retrieve the value for the option
specified by the option_name argument for the 0MQ socket pointed to by
the socket argument, and store it in the buffer pointed to by the
option_value argument. The option_len argument is the size in bytes of
the buffer pointed to by option_value; upon successful completion
zmq_getsockopt() shall modify the option_len argument to indicate the
actual size of the option value stored in the buffer.
The following options can be retrieved with the zmq_getsockopt()
function:
ZMQ_AFFINITY: Retrieve I/O thread affinity
The ZMQ_AFFINITY option shall retrieve the I/O thread affinity for
newly created connections on the specified socket.
Affinity determines which threads from the 0MQ I/O thread pool
associated with the socket’s context shall handle newly created
connections. A value of zero specifies no affinity, meaning that work
shall be distributed fairly among all 0MQ I/O threads in the thread
pool. For non-zero values, the lowest bit corresponds to thread 1,
second lowest bit to thread 2 and so on. For example, a value of 3
specifies that subsequent connections on socket shall be handled
exclusively by I/O threads 1 and 2.
See also zmq_init(3) for details on allocating the number of I/O
threads for a specific context.
Option value type uint64_t
Option value unit N/A (bitmap)
Default value 0
Applicable socket types N/A
ZMQ_BACKLOG: Retrieve maximum length of the queue of outstanding
connections
The ZMQ_BACKLOG option shall retrieve the maximum length of the queue
of outstanding peer connections for the specified socket; this only
applies to connection-oriented transports. For details refer to your
operating system documentation for the listen function.
Option value type int
Option value unit connections
Default value 100
Applicable socket types all, only for
connection-oriented
transports
ZMQ_BINDTODEVICE: Retrieve name of device the socket is bound to
The ZMQ_BINDTODEVICE option retrieves the name of the device this
socket is bound to, eg. an interface or VRF. If a socket is bound to an
interface, only packets received from that interface are processed by
the socket. If device is a VRF device, then subsequent binds/connects
to that socket use addresses in the VRF routing table.
Option value type character string
Option value unit N/A
Default value not set
Applicable socket types all, when using TCP or UDP
transports.
ZMQ_CONNECT_TIMEOUT: Retrieve connect() timeout
Retrieves how long to wait before timing-out a connect() system call.
The connect() system call normally takes a long time before it returns
a time out error. Setting this option allows the library to time out
the call at an earlier interval.
Option value type int
Option value unit milliseconds
Default value 0 (disabled)
Applicable socket types all, when using TCP
transports.
ZMQ_CURVE_PUBLICKEY: Retrieve current CURVE public key
Retrieves the current long term public key for the socket. You can
provide either a 32 byte buffer, to retrieve the binary key value, or a
41 byte buffer, to retrieve the key in a printable Z85 format. NOTE: to
fetch a printable key, the buffer must be 41 bytes large to hold the
40-char key value and one null byte.
Option value type binary data or Z85 text
string
Option value size 32 or 41
Default value null
Applicable socket types all, when using TCP
transport
ZMQ_CURVE_SECRETKEY: Retrieve current CURVE secret key
Retrieves the current long term secret key for the socket. You can
provide either a 32 byte buffer, to retrieve the binary key value, or a
41 byte buffer, to retrieve the key in a printable Z85 format. NOTE: to
fetch a printable key, the buffer must be 41 bytes large to hold the
40-char key value and one null byte.
Option value type binary data or Z85 text
string
Option value size 32 or 41
Default value null
Applicable socket types all, when using TCP
transport
ZMQ_CURVE_SERVERKEY: Retrieve current CURVE server key
Retrieves the current server key for the client socket. You can provide
either a 32 byte buffer, to retrieve the binary key value, or a 41-byte
buffer, to retrieve the key in a printable Z85 format. NOTE: to fetch a
printable key, the buffer must be 41 bytes large to hold the 40-char
key value and one null byte.
Option value type binary data or Z85 text
string
Option value size 32 or 41
Default value null
Applicable socket types all, when using TCP
transport
ZMQ_EVENTS: Retrieve socket event state
The ZMQ_EVENTS option shall retrieve the event state for the specified
socket. The returned value is a bit mask constructed by OR’ing a
combination of the following event flags:
ZMQ_POLLIN
Indicates that at least one message may be received from the
specified socket without blocking.
ZMQ_POLLOUT
Indicates that at least one message may be sent to the specified
socket without blocking.
The combination of a file descriptor returned by the ZMQ_FD option
being ready for reading but no actual events returned by a subsequent
retrieval of the ZMQ_EVENTS option is valid; applications should simply
ignore this case and restart their polling operation/event loop.
Option value type int
Option value unit N/A (flags)
Default value N/A
Applicable socket types all
ZMQ_FD: Retrieve file descriptor associated with the socket
The ZMQ_FD option shall retrieve the file descriptor associated with
the specified socket. The returned file descriptor can be used to
integrate the socket into an existing event loop; the 0MQ library shall
signal any pending events on the socket in an edge-triggered fashion by
making the file descriptor become ready for reading.
Note
The ability to read from the returned file descriptor does not
necessarily indicate that messages are available to be read from,
or can be written to, the underlying socket; applications must
retrieve the actual event state with a subsequent retrieval of the
ZMQ_EVENTS option.
Note
The returned file descriptor is also used internally by the
zmq_send and zmq_recv functions. As the descriptor is edge
triggered, applications must update the state of ZMQ_EVENTS after
each invocation of zmq_send or zmq_recv.To be more explicit: after
calling zmq_send the socket may become readable (and vice versa)
without triggering a read event on the file descriptor.
Caution
The returned file descriptor is intended for use with a poll or
similar system call only. Applications must never attempt to read
or write data to it directly, neither should they try to close it.
Option value type int on POSIX systems,
SOCKET on Windows
Option value unit N/A
Default value N/A
Applicable socket types all
ZMQ_GSSAPI_PLAINTEXT: Retrieve GSSAPI plaintext or encrypted status
Returns the ZMQ_GSSAPI_PLAINTEXT option, if any, previously set on the
socket. A value of 1 means that communications will be plaintext. A
value of 0 means communications will be encrypted.
Option value type int
Option value unit 0, 1
Default value 0 (false)
Applicable socket types all, when using TCP or IPC
transports
ZMQ_GSSAPI_PRINCIPAL: Retrieve the name of the GSSAPI principal
The ZMQ_GSSAPI_PRINCIPAL option shall retrieve the principal name set
for the GSSAPI security mechanism. The returned value shall be a
NULL-terminated string and MAY be empty. The returned size SHALL
include the terminating null byte.
Option value type NULL-terminated character
string
Option value unit N/A
Default value null string
Applicable socket types all, when using TCP or IPC
transports
ZMQ_GSSAPI_SERVER: Retrieve current GSSAPI server role
Returns the ZMQ_GSSAPI_SERVER option, if any, previously set on the
socket.
Option value type int
Option value unit 0, 1
Default value 0 (false)
Applicable socket types all, when using TCP or IPC
transports
ZMQ_GSSAPI_SERVICE_PRINCIPAL: Retrieve the name of the GSSAPI service
principal
The ZMQ_GSSAPI_SERVICE_PRINCIPAL option shall retrieve the principal
name of the GSSAPI server to which a GSSAPI client socket intends to
connect. The returned value shall be a NULL-terminated string and MAY
be empty. The returned size SHALL include the terminating null byte.
Option value type NULL-terminated character
string
Option value unit N/A
Default value null string
Applicable socket types all, when using TCP or IPC
transports
ZMQ_GSSAPI_SERVICE_PRINCIPAL_NAMETYPE: Retrieve nametype for service
principal
Returns the ZMQ_GSSAPI_SERVICE_PRINCIPAL_NAMETYPE option, if any,
previously set on the socket. A value of ZMQ_GSSAPI_NT_HOSTBASED (0)
means the name specified with ZMQ_GSSAPI_SERVICE_PRINCIPAL is
interpreted as a host based name. A value of ZMQ_GSSAPI_NT_USER_NAME
(1) means it is interpreted as a local user name. A value of
ZMQ_GSSAPI_NT_KRB5_PRINCIPAL (2) means it is interpreted as an unparsed
principal name string (valid only with the krb5 GSSAPI mechanism).
Option value type int
Option value unit 0, 1, 2
Default value 0
(ZMQ_GSSAPI_NT_HOSTBASED)
Applicable socket types all, when using TCP or IPC
transports
ZMQ_GSSAPI_PRINCIPAL_NAMETYPE: Retrieve nametype for service principal
Returns the ZMQ_GSSAPI_PRINCIPAL_NAMETYPE option, if any, previously
set on the socket. A value of ZMQ_GSSAPI_NT_HOSTBASED (0) means the
name specified with ZMQ_GSSAPI_PRINCIPAL is interpreted as a host based
name. A value of ZMQ_GSSAPI_NT_USER_NAME (1) means it is interpreted as
a local user name. A value of ZMQ_GSSAPI_NT_KRB5_PRINCIPAL (2) means it
is interpreted as an unparsed principal name string (valid only with
the krb5 GSSAPI mechanism).
Option value type int
Option value unit 0, 1, 2
Default value 0
(ZMQ_GSSAPI_NT_HOSTBASED)
Applicable socket types all, when using TCP or IPC
transports
ZMQ_HANDSHAKE_IVL: Retrieve maximum handshake interval
The ZMQ_HANDSHAKE_IVL option shall retrieve the maximum handshake
interval for the specified socket. Handshaking is the exchange of
socket configuration information (socket type, routing id, security)
that occurs when a connection is first opened, only for
connection-oriented transports. If handshaking does not complete within
the configured time, the connection shall be closed. The value 0 means
no handshake time limit.
Option value type int
Option value unit milliseconds
Default value 30000
Applicable socket types all but ZMQ_STREAM, only
for connection-oriented
transports
ZMQ_IDENTITY: Retrieve socket identity
This option name is now deprecated. Use ZMQ_ROUTING_ID instead.
ZMQ_IDENTITY remains as an alias for now.
ZMQ_IMMEDIATE: Retrieve attach-on-connect value
Retrieve the state of the attach on connect value. If set to 1, will
delay the attachment of a pipe on connect until the underlying
connection has completed. This will cause the socket to block if there
are no other connections, but will prevent queues from filling on pipes
awaiting connection.
Option value type int
Option value unit boolean
Default value 0 (false)
Applicable socket types all, primarily when using
TCP/IPC transports.
ZMQ_INVERT_MATCHING: Retrieve inverted filtering status
Returns the value of the ZMQ_INVERT_MATCHING option. A value of 1 means
the socket uses inverted prefix matching.
On PUB and XPUB sockets, this causes messages to be sent to all
connected sockets except those subscribed to a prefix that matches the
message. On SUB sockets, this causes only incoming messages that do not
match any of the socket’s subscriptions to be received by the user.
Whenever ZMQ_INVERT_MATCHING is set to 1 on a PUB socket, all SUB
sockets connecting to it must also have the option set to 1. Failure to
do so will have the SUB sockets reject everything the PUB socket sends
them. XSUB sockets do not need to do this because they do not filter
incoming messages.
Option value type int
Option value unit 0,1
Default value 0
Applicable socket types ZMQ_PUB, ZMQ_XPUB, ZMQ_SUB
ZMQ_IPV4ONLY: Retrieve IPv4-only socket override status
Retrieve the IPv4-only option for the socket. This option is
deprecated. Please use the ZMQ_IPV6 option.
Option value type int
Option value unit boolean
Default value 1 (true)
Applicable socket types all, when using TCP
transports.
ZMQ_IPV6: Retrieve IPv6 socket status
Retrieve the IPv6 option for the socket. A value of 1 means IPv6 is
enabled on the socket, while 0 means the socket will use only IPv4.
When IPv6 is enabled the socket will connect to, or accept connections
from, both IPv4 and IPv6 hosts.
Option value type int
Option value unit boolean
Default value 0 (false)
Applicable socket types all, when using TCP
transports.
ZMQ_LAST_ENDPOINT: Retrieve the last endpoint set
The ZMQ_LAST_ENDPOINT option shall retrieve the last endpoint bound for
TCP and IPC transports. The returned value will be a string in the form
of a ZMQ DSN. Note that if the TCP host is INADDR_ANY, indicated by a
*, then the returned address will be 0.0.0.0 (for IPv4). Note: not
supported on GNU/Hurd with IPC due to non-working getsockname().
Option value type NULL-terminated character
string
Option value unit N/A
Default value NULL
Applicable socket types all, when binding TCP or
IPC transports
ZMQ_LINGER: Retrieve linger period for socket shutdown
The ZMQ_LINGER option shall retrieve the linger period for the
specified socket. The linger period determines how long pending
messages which have yet to be sent to a peer shall linger in memory
after a socket is closed with zmq_close(3), and further affects the
termination of the socket’s context with zmq_ctx_term(3). The following
outlines the different behaviours:
• The default value of -1 specifies an infinite linger period.
Pending messages shall not be discarded after a call to
zmq_close(); attempting to terminate the socket’s context with
zmq_ctx_term() shall block until all pending messages have been
sent to a peer.
• The value of 0 specifies no linger period. Pending messages shall
be discarded immediately when the socket is closed with
zmq_close().
• Positive values specify an upper bound for the linger period in
milliseconds. Pending messages shall not be discarded after a call
to zmq_close(); attempting to terminate the socket’s context with
zmq_ctx_term() shall block until either all pending messages have
been sent to a peer, or the linger period expires, after which any
pending messages shall be discarded.
Option value type int
Option value unit milliseconds
Default value -1 (infinite)
Applicable socket types all
ZMQ_MAXMSGSIZE: Maximum acceptable inbound message size
The option shall retrieve limit for the inbound messages. If a peer
sends a message larger than ZMQ_MAXMSGSIZE it is disconnected. Value of
-1 means no limit.
Option value type int64_t
Option value unit bytes
Default value -1
Applicable socket types all
ZMQ_MECHANISM: Retrieve current security mechanism
The ZMQ_MECHANISM option shall retrieve the current security mechanism
for the socket.
Option value type int
Option value unit ZMQ_NULL, ZMQ_PLAIN,
ZMQ_CURVE, or ZMQ_GSSAPI
Default value ZMQ_NULL
Applicable socket types all, when using TCP or IPC
transports
ZMQ_MULTICAST_HOPS: Maximum network hops for multicast packets
The option shall retrieve time-to-live used for outbound multicast
packets. The default of 1 means that the multicast packets don’t leave
the local network.
Option value type int
Option value unit network hops
Default value 1
Applicable socket types all, when using multicast
transports
ZMQ_MULTICAST_MAXTPDU: Maximum transport data unit size for multicast
packets
The ZMQ_MULTICAST_MAXTPDU option shall retrieve the maximum transport
data unit size used for outbound multicast packets.
This must be set at or below the minimum Maximum Transmission Unit
(MTU) for all network paths over which multicast reception is required.
Option value type int
Option value unit bytes
Default value 1500
Applicable socket types all, when using multicast
transports
ZMQ_PLAIN_PASSWORD: Retrieve current password
The ZMQ_PLAIN_PASSWORD option shall retrieve the last password set for
the PLAIN security mechanism. The returned value shall be a
NULL-terminated string and MAY be empty. The returned size SHALL
include the terminating null byte.
Option value type NULL-terminated character
string
Option value unit N/A
Default value null string
Applicable socket types all, when using TCP or IPC
transports
ZMQ_PLAIN_SERVER: Retrieve current PLAIN server role
Returns the ZMQ_PLAIN_SERVER option, if any, previously set on the
socket.
Option value type int
Option value unit 0, 1
Default value int
Applicable socket types all, when using TCP or IPC
transports
ZMQ_PLAIN_USERNAME: Retrieve current PLAIN username
The ZMQ_PLAIN_USERNAME option shall retrieve the last username set for
the PLAIN security mechanism. The returned value shall be a
NULL-terminated string and MAY be empty. The returned size SHALL
include the terminating null byte.
Option value type NULL-terminated character
string
Option value unit N/A
Default value null string
Applicable socket types all, when using TCP or IPC
transports
ZMQ_USE_FD: Retrieve the pre-allocated socket file descriptor
The ZMQ_USE_FD option shall retrieve the pre-allocated file descriptor
that has been assigned to a ZMQ socket, if any. -1 shall be returned if
a pre-allocated file descriptor was not set for the socket.
Option value type int
Option value unit file descriptor
Default value -1
Applicable socket types all bound sockets, when
using IPC or TCP transport
ZMQ_PRIORITY: Retrieve the Priority on socket
Gets the protocol-defined priority for all packets to be sent on this
socket, where supported by the OS.
[horizontal]
Option value type:: int
Option value unit:: >0
Default value:: 0
Applicable socket types:: all, only for connection-oriented transports
ZMQ_RATE: Retrieve multicast data rate
The ZMQ_RATE option shall retrieve the maximum send or receive data
rate for multicast transports using the specified socket.
Option value type int
Option value unit kilobits per second
Default value 100
Applicable socket types all, when using multicast
transports
ZMQ_RCVBUF: Retrieve kernel receive buffer size
The ZMQ_RCVBUF option shall retrieve the underlying kernel receive
buffer size for the specified socket. For details refer to your
operating system documentation for the SO_RCVBUF socket option.
Option value type int
Option value unit bytes
Default value 8192
Applicable socket types all
ZMQ_RCVHWM: Retrieve high water mark for inbound messages
The ZMQ_RCVHWM option shall return the high water mark for inbound
messages on the specified socket. The high water mark is a hard limit
on the maximum number of outstanding messages 0MQ shall queue in memory
for any single peer that the specified socket is communicating with. A
value of zero means no limit.
If this limit has been reached the socket shall enter an exceptional
state and depending on the socket type, 0MQ shall take appropriate
action such as blocking or dropping sent messages. Refer to the
individual socket descriptions in zmq_socket(3) for details on the
exact action taken for each socket type.
Option value type int
Option value unit messages
Default value 1000
Applicable socket types all
ZMQ_RCVMORE: More message data parts to follow
The ZMQ_RCVMORE option shall return True (1) if the message part last
received from the socket was a data part with more parts to follow. If
there are no data parts to follow, this option shall return False (0).
Refer to zmq_send(3) and zmq_recv(3) for a detailed description of
multi-part messages.
Option value type int
Option value unit boolean
Default value N/A
Applicable socket types all
ZMQ_RCVTIMEO: Maximum time before a socket operation returns with EAGAIN
Retrieve the timeout for recv operation on the socket. If the value is
0, zmq_recv(3) will return immediately, with a EAGAIN error if there is
no message to receive. If the value is -1, it will block until a
message is available. For all other values, it will wait for a message
for that amount of time before returning with an EAGAIN error.
Option value type int
Option value unit milliseconds
Default value -1 (infinite)
Applicable socket types all
ZMQ_RECONNECT_IVL: Retrieve reconnection interval
The ZMQ_RECONNECT_IVL option shall retrieve the initial reconnection
interval for the specified socket. The reconnection interval is the
period 0MQ shall wait between attempts to reconnect disconnected peers
when using connection-oriented transports. The value -1 means no
reconnection.
Note
The reconnection interval may be randomized by 0MQ to prevent
reconnection storms in topologies with a large number of peers per
socket.
Option value type int
Option value unit milliseconds
Default value 100
Applicable socket types all, only for
connection-oriented
transports
ZMQ_RECONNECT_IVL_MAX: Retrieve maximum reconnection interval
The ZMQ_RECONNECT_IVL_MAX option shall retrieve the maximum
reconnection interval for the specified socket. This is the maximum
period 0MQ shall wait between attempts to reconnect. On each reconnect
attempt, the previous interval shall be doubled untill
ZMQ_RECONNECT_IVL_MAX is reached. This allows for exponential backoff
strategy. Default value means no exponential backoff is performed and
reconnect interval calculations are only based on ZMQ_RECONNECT_IVL.
Note
Values less than ZMQ_RECONNECT_IVL will be ignored.
Option value type int
Option value unit milliseconds
Default value 0 (only use
ZMQ_RECONNECT_IVL)
Applicable socket types all, only for
connection-oriented
transport
ZMQ_RECONNECT_STOP: Retrieve condition where reconnection will stop
The ZMQ_RECONNECT_STOP option shall retrieve the conditions under which
automatic reconnection will stop.
The ZMQ_RECONNECT_STOP_CONN_REFUSED option will stop reconnection when
0MQ receives the ECONNREFUSED return code from the connect. This
indicates that there is no code bound to the specified endpoint.
Option value type int
Option value unit ZMQ_RECONNECT_STOP_CONN_REFUSED
Default value 0
Applicable socket types all, only for
connection-oriented transports
ZMQ_RECOVERY_IVL: Get multicast recovery interval
The ZMQ_RECOVERY_IVL option shall retrieve the recovery interval for
multicast transports using the specified socket. The recovery interval
determines the maximum time in milliseconds that a receiver can be
absent from a multicast group before unrecoverable data loss will
occur.
Option value type int
Option value unit milliseconds
Default value 10000
Applicable socket types all, when using multicast
transports
ZMQ_ROUTING_ID: Retrieve socket routing id
The ZMQ_ROUTING_ID option shall retrieve the routing id of the
specified socket. Routing ids are used only by the request/reply
pattern. Specifically, it can be used in tandem with ROUTER socket to
route messages to the peer with a specific routing id.
A routing id must be at least one byte and at most 255 bytes long.
Identities starting with a zero byte are reserved for use by the 0MQ
infrastructure.
Option value type binary data
Option value unit N/A
Default value NULL
Applicable socket types ZMQ_REP, ZMQ_REQ,
ZMQ_ROUTER, ZMQ_DEALER.
ZMQ_SNDBUF: Retrieve kernel transmit buffer size
The ZMQ_SNDBUF option shall retrieve the underlying kernel transmit
buffer size for the specified socket. For details refer to your
operating system documentation for the SO_SNDBUF socket option.
Option value type int
Option value unit bytes
Default value 8192
Applicable socket types all
ZMQ_SNDHWM: Retrieves high water mark for outbound messages
The ZMQ_SNDHWM option shall return the high water mark for outbound
messages on the specified socket. The high water mark is a hard limit
on the maximum number of outstanding messages 0MQ shall queue in memory
for any single peer that the specified socket is communicating with. A
value of zero means no limit.
If this limit has been reached the socket shall enter an exceptional
state and depending on the socket type, 0MQ shall take appropriate
action such as blocking or dropping sent messages. Refer to the
individual socket descriptions in zmq_socket(3) for details on the
exact action taken for each socket type.
Option value type int
Option value unit messages
Default value 1000
Applicable socket types all
ZMQ_SNDTIMEO: Maximum time before a socket operation returns with EAGAIN
Retrieve the timeout for send operation on the socket. If the value is
0, zmq_send(3) will return immediately, with a EAGAIN error if the
message cannot be sent. If the value is -1, it will block until the
message is sent. For all other values, it will try to send the message
for that amount of time before returning with an EAGAIN error.
Option value type int
Option value unit milliseconds
Default value -1 (infinite)
Applicable socket types all
ZMQ_SOCKS_PROXY: Retrieve SOCKS5 proxy address
The ZMQ_SOCKS_PROXY option shall retrieve the SOCKS5 proxy address in
string format. The returned value shall be a NULL-terminated string and
MAY be empty. The returned size SHALL include the terminating null
byte.
Option value type NULL-terminated character
string
Option value unit N/A
Default value null string
Applicable socket types all, when using TCP
transports
ZMQ_TCP_KEEPALIVE: Override SO_KEEPALIVE socket option
Override SO_KEEPALIVE socket option(where supported by OS). The default
value of -1 means to skip any overrides and leave it to OS default.
Option value type int
Option value unit -1,0,1
Default value -1 (leave to OS default)
Applicable socket types all, when using TCP
transports.
ZMQ_TCP_KEEPALIVE_CNT: Override TCP_KEEPCNT socket option
Override TCP_KEEPCNT socket option(where supported by OS). The default
value of -1 means to skip any overrides and leave it to OS default.
Option value type int
Option value unit -1,>0
Default value -1 (leave to OS default)
Applicable socket types all, when using TCP
transports.
ZMQ_TCP_KEEPALIVE_IDLE: Override TCP_KEEPIDLE (or TCP_KEEPALIVE on some OS)
Override TCP_KEEPIDLE(or TCP_KEEPALIVE on some OS) socket option (where
supported by OS). The default value of -1 means to skip any overrides
and leave it to OS default.
Option value type int
Option value unit -1,>0
Default value -1 (leave to OS default)
Applicable socket types all, when using TCP
transports.
ZMQ_TCP_KEEPALIVE_INTVL: Override TCP_KEEPINTVL socket option
Override TCP_KEEPINTVL socket option(where supported by OS). The
default value of -1 means to skip any overrides and leave it to OS
default.
Option value type int
Option value unit -1,>0
Default value -1 (leave to OS default)
Applicable socket types all, when using TCP
transports.
ZMQ_TCP_MAXRT: Retrieve Max TCP Retransmit Timeout
On OSes where it is supported, retrieves how long before an
unacknowledged TCP retransmit times out. The system normally attempts
many TCP retransmits following an exponential backoff strategy. This
means that after a network outage, it may take a long time before the
session can be re-established. Setting this option allows the timeout
to happen at a shorter interval.
Option value type int
Option value unit milliseconds
Default value 0 (leave to OS default)
Applicable socket types all, when using TCP
transports.
ZMQ_THREAD_SAFE: Retrieve socket thread safety
The ZMQ_THREAD_SAFE option shall retrieve a boolean value indicating
whether or not the socket is threadsafe. See zmq_socket(3) for which
sockets are thread-safe.
Option value type int
Option value unit boolean
Applicable socket types all
ZMQ_TOS: Retrieve the Type-of-Service socket override status
Retrieve the IP_TOS option for the socket.
Option value type int
Option value unit >0
Default value 0
Applicable socket types all, only for
connection-oriented
transports
ZMQ_TYPE: Retrieve socket type
The ZMQ_TYPE option shall retrieve the socket type for the specified
socket. The socket type is specified at socket creation time and cannot
be modified afterwards.
Option value type int
Option value unit N/A
Default value N/A
Applicable socket types all
ZMQ_ZAP_DOMAIN: Retrieve RFC 27 authentication domain
The ZMQ_ZAP_DOMAIN option shall retrieve the last ZAP domain set for
the socket. The returned value shall be a NULL-terminated string and
MAY be empty. An empty string means that ZAP authentication is
disabled. The returned size SHALL include the terminating null byte.
Option value type character string
Option value unit N/A
Default value not set
Applicable socket types all, when using TCP
transport
ZMQ_ZAP_ENFORCE_DOMAIN: Retrieve ZAP domain handling mode
The ZMQ_ZAP_ENFORCE_DOMAIN option shall retrieve the flag that
determines whether a ZAP domain is strictly required or not.
Option value type int
Option value unit 0, 1
Default value 0
Applicable socket types all, when using ZAP
ZMQ_VMCI_BUFFER_SIZE: Retrieve buffer size of the VMCI socket
The ZMQ_VMCI_BUFFER_SIZE option shall retrieve the size of the
underlying buffer for the socket. Used during negotiation before the
connection is established.
Option value type uint64_t
Option value unit bytes
Default value 65546
Applicable socket types all, when using VMCI
transport
ZMQ_VMCI_BUFFER_MIN_SIZE: Retrieve min buffer size of the VMCI socket
The ZMQ_VMCI_BUFFER_MIN_SIZE option shall retrieve the min size of the
underlying buffer for the socket. Used during negotiation before the
connection is established.
Option value type uint64_t
Option value unit bytes
Default value 128
Applicable socket types all, when using VMCI
transport
ZMQ_VMCI_BUFFER_MAX_SIZE: Retrieve max buffer size of the VMCI socket
The ZMQ_VMCI_BUFFER_MAX_SIZE option shall retrieve the max size of the
underlying buffer for the socket. Used during negotiation before the
connection is established.
Option value type uint64_t
Option value unit bytes
Default value 262144
Applicable socket types all, when using VMCI
transport
ZMQ_VMCI_CONNECT_TIMEOUT: Retrieve connection timeout of the VMCI socket
The ZMQ_VMCI_CONNECT_TIMEOUT option shall retrieve connection timeout
for the socket.
Option value type int
Option value unit milliseconds
Default value -1
Applicable socket types all, when using VMCI
transport
ZMQ_MULTICAST_LOOP: Retrieve multicast local loopback configuration
Retrieve the current multicast loopback configuration. A value of 1
means that the multicast packets sent on this socket will be looped
back to local listening interface.
Option value type int
Option value unit 0, 1
Default value 1
Applicable socket types ZMQ_RADIO, when using UDP
multicast transport
ZMQ_ROUTER_NOTIFY: Retrieve router socket notification settings
Retrieve the current notification settings of a router socket. The
returned value is a bitmask composed of ZMQ_NOTIFY_CONNECT and
ZMQ_NOTIFY_DISCONNECT flags, meaning connect and disconnect
notifications are enabled, respectively. A value of 0 means the
notifications are off.
Note
in DRAFT state, not yet available in stable releases.
Option value type int
Option value unit 0, ZMQ_NOTIFY_CONNECT,
ZMQ_NOTIFY_DISCONNECT,
ZMQ_NOTIFY_CONNECT |
ZMQ_NOTIFY_DISCONNECT
Default value 0
Applicable socket types ZMQ_ROUTER
ZMQ_IN_BATCH_SIZE: Maximal receive batch size
Gets the maximal amount of messages that can be received in a single
recv system call.
Cannot be zero.
Note
in DRAFT state, not yet available in stable releases.
Option value type int
Option value unit messages
Default value 8192
Applicable socket types All, when using TCP, IPC,
PGM or NORM transport.
ZMQ_OUT_BATCH_SIZE: Maximal send batch size
Gets the maximal amount of messages that can be sent in a single send
system call.
Cannot be zero.
Note
in DRAFT state, not yet available in stable releases.
Option value type int
Option value unit messages
Default value 8192
Applicable socket types All, when using TCP, IPC,
PGM or NORM transport.
RETURN VALUE
The zmq_getsockopt() function shall return zero if successful.
Otherwise it shall return -1 and set errno to one of the values defined
below.
ERRORS
EINVAL
The requested option option_name is unknown, or the requested
option_len or option_value is invalid, or the size of the buffer
pointed to by option_value, as specified by option_len, is
insufficient for storing the option value.
ETERM
The 0MQ context associated with the specified socket was
terminated.
ENOTSOCK
The provided socket was invalid.
EINTR
The operation was interrupted by delivery of a signal.
EXAMPLE
Retrieving the high water mark for outgoing messages.
/* Retrieve high water mark into sndhwm */
int sndhwm;
size_t sndhwm_size = sizeof (sndhwm);
rc = zmq_getsockopt (socket, ZMQ_SNDHWM, &sndhwm, &sndhwm_size);
assert (rc == 0);
SEE ALSO
zmq_setsockopt(3) zmq_socket(3) zmq(7)
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 01/18/2023 ZMQ_GETSOCKOPT(3)
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