svcadm(8)을 검색하려면 섹션에서 8 을 선택하고, 맨 페이지 이름에 svcadm을 입력하고 검색을 누른다.
setsockopt(3c)
getsockopt(3C) Standard C Library Functions getsockopt(3C)
NAME
getsockopt, setsockopt - get and set options on sockets
SYNOPSIS
#include <sys/socket.h>
int getsockopt(int s, int level, int optname, void *restrict optval,
socklen_t *restrict optlen);
int setsockopt(int s, int level, int optname, const void *optval,
socklen_t optlen);
DESCRIPTION
The getsockopt() and setsockopt() functions manipulate options associ‐
ated with a socket. Options may exist at multiple protocol levels; they
are always present at the uppermost "socket" level.
The level argument specifies the protocol level at which the option re‐
sides. To manipulate options at the socket level, specify the level ar‐
gument as SOL_SOCKET. To manipulate options at the protocol level, sup‐
ply the appropriate protocol number for the protocol controlling the
option. For example, to indicate that an option will be interpreted by
the TCP, set level to the protocol number of TCP, as defined in the
<netinet/in.h> header, or as determined by using getprotobyname(3C).
Some socket protocol families may also define additional levels, such
as SOL_ROUTE. Only socket-level options are described here.
The parameters optval and optlen are used to access option values for
setsockopt(). For getsockopt(), they identify a buffer in which the
value(s) for the requested option(s) are to be returned. For getsock‐
opt(), optlen is a value-result parameter, initially containing the
size of the buffer pointed to by optval, and modified on return to in‐
dicate the actual size of the value returned. Use a 0 optval if no op‐
tion value is to be supplied or returned.
The optname and any specified options are passed uninterpreted to the
appropriate protocol module for interpretation. The include file
<sys/socket.h> contains definitions for the socket-level options de‐
scribed below. Options at other protocol levels vary in format and
name.
Most socket-level options take an int for optval. For setsockopt(), the
optval parameter should be non-zero to enable a boolean option, or zero
if the option is to be disabled. SO_LINGER uses a struct linger parame‐
ter that specifies the desired state of the option and the linger in‐
terval. struct linger is defined in <sys/socket.h>. struct linger con‐
tains the following members:
l_onoff on = 1/off = 0
l_linger linger time, in seconds
The following options are recognized at the socket level. Except as
noted, each may be examined with getsockopt() and set with setsock‐
opt().
SO_DEBUG enable/disable recording of debugging information
SO_REUSEADDR enable/disable local address reuse
SO_REUSEPORT enable/disable local port reuse for TCP/SCTP/UDP
socket
SO_KEEPALIVE enable/disable keep connections alive
SO_DONTROUTE enable/disable routing bypass for outgoing mes‐
sages
SO_LINGER linger on close if data is present
SO_BROADCAST enable/disable permission to transmit broadcast
messages
SO_OOBINLINE enable/disable reception of out-of-band data in
band
SO_SNDBUF set buffer size for output
SO_RCVBUF set buffer size for input
SO_SNDTIMEO set the send timeout for socket
SO_RCVTIMEO set the receive timeout for socket
SO_DGRAM_ERRIND application wants delayed error
SO_TIMESTAMP enable/disable reception of timestamp with data‐
grams
SO_LISTENQLIMIT get the current value of listen queue limit (ini‐
tially set using the backlog argument of lis‐
ten(3C)). This option is available only with the
getsockopt() function.
SO_EXCLBIND enable/disable exclusive binding of the socket
SO_TYPE get the type of the socket (get only)
SO_ERROR get and clear error on the socket (get only)
In addition to SO_ERROR, the socket error is re‐
trieved and cleared by any ioctl(2) invocation.
In this case, the device driver detects socket
error and passes it through ioctl() without
change to the caller.
SO_MAC_EXEMPT get or set mandatory access control on the
socket. This option is available only when the
system is configured with Trusted Extensions.
SO_ALLZONES bypass zone boundaries (privileged).
SO_DOMAIN get the domain used in the socket (get only)
SO_PROTOTYPE for socket in domains PF_INET and PF_INET6, get
the underlying protocol number used in the
socket. For socket in domain PF_ROUTE, get the
address family used in the socket.
SO_PASSIVE_CONNECT modify connect(3C) to wait for connection request
from a peer instead of initiating a connection
request to it. It is applicable to TCP/SCTP
PF_INET/PF_INET6 socket.
SO_FLOW_SLA set per socket service level properties: priority
and bandwidth limit.
It is applicable to TCP/UDP PF_INET/PF_INET6
sockets. Requires PRIV_SYS_FLOW_CONFIG privilege.
SO_FLOW_NAME Make the socket a flow filter of the specified
MAC flow.
It is applicable to TCP/UDP PF_INET/PF_INET6
sockets. Requires PRIV_SYS_FLOW_CONFIG privilege.
SO_NOSIGPIPE Get and set whether this specific socket only re‐
turns EPIPE on write when the socket is discon‐
nected, or whether a SIGPIPE signal is also sent.
SO_RECVUCRED enable/disable receiving the senders credential
using a SCM_UCRED message. Only supported on
SOCK_DGRAM sockets. See ucred_get(3C).
The SO_DEBUG option enables debugging in the underlying protocol mod‐
ules. The SO_REUSEADDR or SO_REUSEPORT options indicate that the rules
used in validating addresses and ports supplied in a bind() call should
allow reuse of local addresses or ports. For more information, see the
bind(3C) man page. The SO_REUSEPORT option must be set by all the sock‐
ets including the first socket, before calling bind() to enable reuse.
All the calling processes must have the same effective UID for the
bind() call to succeed. This option allows multiple listeners binding
to the same local address or port pair. For TCP/SCTP socket, new incom‐
ing connection requests will be distributed across those listeners
bound to the same local address or port pair. For UDP socket, incoming
datagrams will be distributed across those bound sockets. The algorithm
used to determine how to select a socket using this option to deliver
an incoming TCP/SCTP connection request or an UDP datagram can be
changed by modifying the ipadm protocol property, reuseport-lbalg. The
current supported algorithms are:
o Round Robin (rr)
o Hashing on source IP address (src-ip)
o Hashing on source IP address and source port (src-ip-port)
o Hashing on source and destination IP address (src-dst-ip)
o Hashing on all 4 tuples (src-dst-ip-ports)
The string in parenthesis is the value used in ipadm to represent the
algorithm. For more information, see the ipadm(8) man page.
The SO_KEEPALIVE option enables the periodic transmission of messages
on a connected socket. If the connected party fails to respond to these
messages, the connection is considered broken and threads using the
socket are notified using a SIGPIPE signal.
The SO_DONTROUTE option indicates that outgoing messages should bypass
the standard routing facilities. Instead, messages are directed to the
appropriate network interface according to the network portion of the
destination address.
The SO_LINGER option controls the action taken when unsent messages are
queued on a socket and a close(2) is performed. If the socket promises
reliable delivery of data and SO_LINGER is set, the system will block
the thread on the close() attempt until it is able to transmit the data
or until it decides it is unable to deliver the information (a timeout
period, termed the linger interval, is specified in the setsockopt()
call when SO_LINGER is requested). If SO_LINGER is disabled and a
close() is issued, the system will process the close() in a manner that
allows the thread to continue as quickly as possible.
The option SO_BROADCAST requests permission to send broadcast datagrams
on the socket. With protocols that support out-of-band data, the
SO_OOBINLINE option requests that out-of-band data be placed in the
normal data input queue as received; it will then be accessible with
recv() or read() calls without the MSG_OOB flag.
The SO_SNDBUF and SO_RCVBUF options adjust the normal buffer sizes al‐
located for output and input buffers, respectively. The buffer size may
be increased for high-volume connections or may be decreased to limit
the possible backlog of incoming data. The maximum buffer size for
UDP/TCP is determined by the value of the ipadm variable max_buf for
that particular protocol. Use the ipadm(8) utility to determine the
current default values. See the Oracle Solaris 11.4 Tunable Parameters
Reference Manual for information on setting the values of max_buf for
either TCP, UDP, or both. At present, lowering SO_RCVBUF on a TCP con‐
nection after it has been established has no effect.
The SO_SNDTIMEO and SO_RCVTIMEO options specify the timeout for socket
I/O functions. Both options take a pointer to struct timeval as their
argument. The default timeout value is zero, which means the socket I/O
functions will never timeout. If the timeout expires and no data has
been sent, the socket I/O functions will return -1 and set errno to EA‐
GAIN or EWOULDBLOCK. If some data has already been transferred when
timeout fires, the socket I/O functions will return the number of bytes
transferred so far. The socket functions affected by this option are
write(), send(), sendto(), sendmsg(), read(), recv(), recvfrom(), and
recvmsg().
By default, delayed errors (such as ICMP port unreachable packets) are
returned only for connected datagram sockets. The SO_DGRAM_ERRIND op‐
tion makes it possible to receive errors for datagram sockets that are
not connected. When this option is set, certain delayed errors received
after completion of a sendto() or sendmsg() operation will cause a sub‐
sequent sendto() or sendmsg() operation using the same destination ad‐
dress (to parameter) to fail with the appropriate error. See send(3C).
If the SO_TIMESTAMP option is enabled on a SO_DGRAM or a SO_RAW socket,
the recvmsg(3C) call will return a timestamp in the native data format,
corresponding to when the datagram was received.
The SO_EXCLBIND option is used to enable or disable the exclusive bind‐
ing of a socket. It overrides the use of the SO_REUSEADDR option to
reuse an address on bind(3C). The actual semantics of the SO_EXCLBIND
option depend on the underlying protocol. See tcp(4P) or udp(4P) for
more information.
The SO_TYPE and SO_ERROR options are used only with getsockopt(). The
SO_TYPE option returns the type of the socket, for example,
SOCK_STREAM. It is useful for servers that inherit sockets on startup.
The SO_ERROR option returns any pending error on the socket and clears
the error status. It may be used to check for asynchronous errors on
connected datagram sockets or for other asynchronous errors.
The SO_MAC_EXEMPT option is used to toggle socket behavior with unla‐
beled peers. A socket that has this option enabled can communicate with
an unlabeled peer if it is in the global zone or has a label that domi‐
nates the default label of the peer. Otherwise, the socket must have a
label that is equal to the default label of the unlabeled peer. Calling
setsockopt() with this option returns an EACCES error if the process
lacks the NET_MAC_AWARE privilege or if the socket is bound. The
SO_MAC_EXEMPT option is available only when the system is configured
with Trusted Extensions.
The SO_ALLZONES option can be used to bypass zone boundaries between
shared-IP zones. Normally, the system prevents a socket from being
bound to an address that is not assigned to the current zone. It also
prevents a socket that is bound to a wildcard address from receiving
traffic for other zones. However, some daemons which run in the global
zone might need to send and receive traffic using addresses that belong
to other shared-IP zones. If set before a socket is bound, SO_ALLZONES
causes the socket to ignore zone boundaries between shared-IP zones and
permits the socket to be bound to any address assigned to the shared-IP
zones. If the socket is bound to a wildcard address, it receives traf‐
fic intended for all shared-IP zones and behaves as if an equivalent
socket were bound in each active shared-IP zone. Applications that use
the SO_ALLZONES option to initiate connections or send datagram traffic
should specify the source address for outbound traffic by binding to a
specific address. There is no effect from setting this option in an ex‐
clusive-IP zone. Setting this option requires the sys_net_config privi‐
lege. See zones(7).
The SO_PASSIVE_CONNECT option can be used to modify connect() semantics
for TCP and SCTP socket. After this option is set, calling connect() on
the socket will not initiate a connection setup sequence. Instead, the
transport end point is in listen state waiting for a connection request
from the remote peer specified in connect(). After the expected connec‐
tion is established, connect() returns.
The SO_FLOW_SLA socket option can be used to set per socket service
level properties for the socket. The properties, priority, and band‐
width limit are supported in SOCK_FLOW_PROP_VERSION1. These properties
are effective for both outbound and inbound packets. Only TCP and UDP
PF_INET/PF_INET6 sockets are supported at this time.
The SO_FLOW_SLA socket option takes a pointer to a sock_flow_props_t
structure as the value:
typedef struct sock_flow_props_s {
int sfp_version;
uint32_t sfp_mask;
int sfp_priority; /* flow priority */
uint64_t sfp_maxbw; /* bandwidth limit in bps */
int sfp_status; /* flow create status for getsockopt */
} sock_flow_props_t;
#define SOCK_FLOW_PROP_VERSION1 1
/* bit mask values for sfp_mask */
#define SFP_MAXBW 0x00000001 /* BW Limit */
#define SFP_PRIORITY 0x00000008 /* Priority */
/* possible values for sfp_priority */
#define SFP_PRIO_NORMAL 1
#define SFP_PRIO_HIGH 2
A value of 0 for sfp_maxbw drops all packets for the socket.
The status of the flow creation can be obtained by a getsockopt(). The
sfp_status field indicates the status. A value of 0 means a flow is
successfully created. In case of an error, this field has the errno to
indicate the error. This field is not set during setsockopt() and is
ignored.
USAGE
Example 1 Creating and using flows
/* a. at the time of socket(3c) call */
sock_flow_props_t sprop;
...
sock = socket(AF_INET, SOCK_DGRAM, 0);
sprop.sfp_version = SOCK_FLOW_PROP_VERSION1;
sprop.sfp_mask = SFP_PRIORITY;
sprop.sfp_priority = SFP_PRIO_HIGH;
setsockopt(sock, SOL_SOCKET, SO_FLOW_SLA, &sprop,
sizeof (sprop));
...
/* b. at the time of the accept(3c) call */
sock_flow_props_t sprop;
...
newsock = accept(listen_sock, (struct sockaddr *)&from,
&fromlen);
// construct sprop
setsockopt(newsock, SOL_SOCKET, SO_FLOW_SLA, &sprop,
sizeof (sprop));
...
A socket application using this socket option, causes the system to
create a system flow. flowadm(8) can be used to observe these flows.
These system generated flows have the prefix <id>.sys.sock.
The pfiles command prints the SO_FLOW_SLA socket option along with the
other socket options.
Creation of a system flow requires the link name and the 5-tuple in
case of a connected socket and the local 3-tuple in case of a lis‐
tener/bound socket. The following restrictions exist for the cases
where a link name or a value in the 5-tuple/3-tuple can not be obtained
given a socket. Some of these restrictions may be relaxed in future.
o Sockets using IP loopback addresses (/dev/lo0) are not sup‐
ported.
o Only connected UDP is supported. This means the socket call,
connect(), must be made for the option to be enforced.
o INADDR_ANY IP address is not supported. So, the socket call,
bind(), must pass an IP address for the option to be en‐
forced.
Note that a flow is not created if the above conditions are not met. It
is not an error (i.e. bind/connect would not fail) if a flow is not
created. getsockopt() should be used to determine if a flow is created.
SO_FLOW_NAME socket option makes a socket a member of the specified MAC
flow. Multiple sockets can belong to the same flow. Each socket maps to
a flow filter. The flow is created if it does not already exist. If the
flow exists, it is assumed that the flow name is known and the applica‐
tion got it out of band.
The following is an example code using SO_FLOW_NAME:
char flow[MAXUSERFLOWNAMELEN];
(void) strlcpy(flow, "tenantA", MAXUSERFLOWNAMELEN);
/* Assign a socket to the flow */
rv = setsockopt(sock1, SOL_SOCKET, SO_FLOW_NAME, flow, strlen(flow));
rv = setsockopt(sock2, SOL_SOCKET, SO_FLOW_NAME, flow, strlen(flow));
...
An application can use either SO_FLOW_SLA or SO_FLOW_NAME option exclu‐
sively. They can also be used together with the following rules.
For a given socket, this sequence of setsockopt() calls is allowed:
setsockopt(s, SO_FLOW_NAME, ...)
setsockopt(s, SO_FLOW_SLA, ...)
In this case, the SLA on the flow is modified. SO_FLOW_SLA does not
create any system flow though the socket already belongs to a flow as
indicated by SO_FLOW_NAME.
For a given socket, this sequence is not allowed:
setsockopt(s, SO_FLOW_SLA, ...);
setsockopt(s, SO_FLOW_NAME, ...);
We do not allow this because we already create a system flow
<int>.sys.sock for the first call. The second call fails in this case.
getsockopt() can be called with either of the socket options at any
time.
RETURN VALUES
If successful, getsockopt() and setsockopt() return 0. Otherwise, the
functions return −1 and set errno to indicate the error.
ERRORS
The getsockopt() and setsockopt() calls succeed unless:
EBADF The argument s is not a valid file descriptor.
EACCES Permission denied.
EADDRINUSE Address already joined for IP_ADD_MEMBERSHIP.
EADDRNOTAVAIL Bad interface address for IP_ADD_MEMBERSHIP and
IP_DROP_MEMBERSHIP.
EHOSTUNREACH Invalid address for IP_MULTICAST_IF.
EINVAL Invalid length for IP_OPTIONS.
Not a multicast address for IP_ADD_MEMBERSHIP and
IP_DROP_MEMBERSHIP.
The specified option is invalid at the specified
socket level, or the socket has been shut down.
ENOBUFS SO_SNDBUF or SO_RCVBUF exceeds a system limit.
ENOENT Address not joined for IP_DROP_MEMBERSHIP.
ENOMEM There was insufficient memory available for the opera‐
tion to complete.
ENOPROTOOPT The option is unknown at the level indicated.
ENOSR There were insufficient STREAMS resources available
for the operation to complete.
ENOTSOCK The argument s is not a socket.
EPERM No permissions or sufficient privileges.
ENOTCONN Flow creation status for getsockopt() for SO_FLOW_SLA.
No flow is created yet as the application did not do a
connect or bind.
EOPNOTSUPP Flow creation status for getsockopt() for SO_FLOW_SLA.
Flow creation is not supported for this socket.
EALREADY A flow with identical attributes exists.
EINPROGRESS A flow is being created.
ATTRIBUTES
See attributes(7) for descriptions of the following attributes:
tab() box; cw(2.75i) |cw(2.75i) lw(2.75i) |lw(2.75i) ATTRIBUTE TYPEAT‐
TRIBUTE VALUE _ Interface StabilityCommitted _ MT-LevelAsync-Signal-
Safe _ StandardSee standards(7).
SEE ALSO
close(2), ioctl(2), read(2), write(2), bind(3C), connect(3C),
getprotobyname(3C), recv(3C), recvmsg(3C), send(3C), socket(3C),
socket.h(3HEAD), tcp(4P), udp(4P), attributes(7), zones(7), flowadm(8),
ipadm(8)
Oracle Solaris 11.4 Tunable Parameters Reference Manual
HISTORY
The getsockopt() and setsockopt() functions have been present since the
initial release of Solaris.
Support for the following options is available in Oracle Solaris start‐
ing with the listed release:
tab() box; cw(4.71i) |cw(0.79i) lw(4.71i) |lw(0.79i) OPTIONRELEASE _
SO_FLOW_NAME, SO_NOSIGPIPE11.4.0 _ SO_LISTENQLIMIT11.3.22 _
SO_FLOW_SLA11.2.0 _ T{ SO_EXCLBIND, SO_PASSIVE_CONNECT, SO_REUSEPORT,
SO_TIMESTAMP T}11.0.0 _ SO_DOMAIN10 4/08 (Update 5) _ SO_ALLZONES10
8/07 (Update 4) _ SO_MAC_EXEMPT10 11/06 (Update 3) _ SO_RECVUCRED10
3/05 _ SO_DGRAM_ERRIND2.6 _ T{ SO_BROADCAST, SO_DEBUG, SO_DONTROUTE,
SO_ERROR, SO_KEEPALIVE, SO_LINGER, SO_OOBINLINE, SO_PROTOTYPE,
SO_RCVBUF, SO_RCVTIMEO, SO_REUSEADDR, SO_SNDBUF, SO_SNDTIMEO, SO_TYPE
T}2.0
Oracle Solaris 11.4 2 Feb 2021 getsockopt(3C)