1NN_GETSOCKOPT(3) nanomsg 1.1.5 NN_GETSOCKOPT(3)
2
6 nn_getsockopt - retrieve a socket option
7
9 #include <nanomsg/nn.h>
10 int nn_getsockopt (int s, int level, int option, void *optval, size_t
12 *optvallen);
13
15 Retrieves the value for the option. The level argument specifies the
16 protocol level at which the option resides. For generic socket-level
17 options use NN_SOL_SOCKET level. For socket-type-specific options use
18 socket type for level argument (e.g. NN_SUB). For transport-specific
19 options use ID of the transport as the level argument (e.g. NN_TCP).
20 The value is stored in the buffer pointed to by optval argument. Size
22 of the buffer is specified by the optvallen argument. If the size of
23 the option is greater than size of the buffer, the value will be
24 silently truncated. Otherwise, the optvallen will be modified to
25 indicate the actual length of the option.
26 <nanomsg/nn.h> header defines generic socket-level options
28 (NN_SOL_SOCKET level). The options are as follows:
29 NN_DOMAIN
31 Returns the domain constant as it was passed to nn_socket().
32 NN_PROTOCOL
34 Returns the protocol constant as it was passed to nn_socket().
35 NN_LINGER
37 Specifies how long the socket should try to send pending outbound
38 messages after nn_close() have been called, in milliseconds.
39 Negative value means infinite linger. The type of the option is
40 int. Default value is 1000 (1 second).
41 NN_SNDBUF
43 Size of the send buffer, in bytes. To prevent blocking for messages
44 larger than the buffer, exactly one message may be buffered in
45 addition to the data in the send buffer. The type of this option is
46 int. Default value is 128kB.
47 NN_RCVBUF
49 Size of the receive buffer, in bytes. To prevent blocking for
50 messages larger than the buffer, exactly one message may be
51 buffered in addition to the data in the receive buffer. The type of
52 this option is int. Default value is 128kB.
53 NN_RCVMAXSIZE
55 Maximum message size that can be received, in bytes. Negative value
56 means that the received size is limited only by available
57 addressable memory. The type of this option is int. Default is
58 1024kB.
59 NN_SNDTIMEO
61 The timeout for send operation on the socket, in milliseconds. If
62 message cannot be sent within the specified timeout, ETIMEDOUT
63 error is returned. Negative value means infinite timeout. The type
64 of the option is int. Default value is -1.
65 NN_RCVTIMEO
67 The timeout for recv operation on the socket, in milliseconds. If
68 message cannot be received within the specified timeout, ETIMEDOUT
69 error is returned. Negative value means infinite timeout. The type
70 of the option is int. Default value is -1.
71 NN_RECONNECT_IVL
73 For connection-based transports such as TCP, this option specifies
74 how long to wait, in milliseconds, when connection is broken before
75 trying to re-establish it. Note that actual reconnect interval may
76 be randomised to some extent to prevent severe reconnection storms.
77 The type of the option is int. Default value is 100 (0.1 second).
78 NN_RECONNECT_IVL_MAX
80 This option is to be used only in addition to NN_RECONNECT_IVL
81 option. It specifies maximum reconnection interval. On each
82 reconnect attempt, the previous interval is doubled until
83 NN_RECONNECT_IVL_MAX is reached. Value of zero means that no
84 exponential backoff is performed and reconnect interval is based
85 only on NN_RECONNECT_IVL. If NN_RECONNECT_IVL_MAX is less than
86 NN_RECONNECT_IVL, it is ignored. The type of the option is int.
87 Default value is 0.
88 NN_SNDPRIO
90 Retrieves outbound priority currently set on the socket. This
91 option has no effect on socket types that send messages to all the
92 peers. However, if the socket type sends each message to a single
93 peer (or a limited set of peers), peers with high priority take
94 precedence over peers with low priority. The type of the option is
95 int. Highest priority is 1, lowest priority is 16. Default value is
96 8.
97 NN_RCVPRIO
99 Sets inbound priority for endpoints subsequently added to the
100 socket. This option has no effect on socket types that are not able
101 to receive messages. When receiving a message, messages from peer
102 with higher priority are received before messages from peer with
103 lower priority. The type of the option is int. Highest priority is
104 1, lowest priority is 16. Default value is 8.
105 NN_IPV4ONLY
107 If set to 1, only IPv4 addresses are used. If set to 0, both IPv4
108 and IPv6 addresses are used. The type of the option is int. Default
109 value is 1.
110 NN_SNDFD
112 Retrieves a file descriptor that is readable when a message can be
113 sent to the socket. The descriptor should be used only for polling
114 and never read from or written to. The type of the option is same
115 as the type of file descriptor on the platform. That is, int on
116 POSIX-complaint platforms and SOCKET on Windows. The descriptor
117 becomes invalid and should not be used any more once the socket is
118 closed. This socket option is not available for unidirectional
119 recv-only socket types.
120 NN_RCVFD
122 Retrieves a file descriptor that is readable when a message can be
123 received from the socket. The descriptor should be used only for
124 polling and never read from or written to. The type of the option
125 is same as the type of file descriptor on the platform. That is,
126 int on POSIX-complaint platforms and SOCKET on Windows. The
127 descriptor becomes invalid and should not be used any more once the
128 socket is closed. This socket option is not available for
129 unidirectional send-only socket types.
130 NN_SOCKET_NAME
132 Socket name for error reporting and statistics. The type of the
133 option is string. Default value is "N" where N is socket integer.
134 This option is experimental, see nn_env(7) for details
135 NN_MAXTTL
137 Retrieves the maximum number of "hops" a message can go through
138 before it is dropped. Each time the message is received (for
139 example via the nn_device(3) function) counts as a single hop. This
140 provides a form of protection against inadvertent loops.
141
143 If the function succeeds zero is returned. Otherwise, -1 is returned
144 and errno is set to to one of the values defined below.
145
147 EBADF
148 The provided socket is invalid.
149 ENOPROTOOPT
151 The option is unknown at the level indicated.
152 ETERM
154 The library is terminating.
155
157 int linger;
158 size_t sz = sizeof (linger);
159 nn_getsockopt (s, NN_SOL_SOCKET, NN_LINGER, &linger, &sz);
160
162 nn_socket(3) nn_setsockopt(3) nanomsg(7)
163
165 Martin Sustrik <sustrik@250bpm.com> Garrett D’Amore
166 <garrett@damore.org>
167 2021-01-26 NN_GETSOCKOPT(3)