# PRSocketOptionData

Type for structure used with {ref}`PR_GetSocketOption` and
{ref}`PR_SetSocketOption` to specify options for file descriptors that
represent sockets.

## Syntax

```{code}
#include <prio.h>

typedef struct PRSocketOptionData
{
  PRSockOption option;
  union
  {
     PRUintn ip_ttl;
     PRUintn mcast_ttl;
     PRUintn tos;
     PRBool non_blocking;
     PRBool reuse_addr;
     PRBool keep_alive;
     PRBool mcast_loopback;
     PRBool no_delay;
     PRSize max_segment;
     PRSize recv_buffer_size;
     PRSize send_buffer_size;
     PRLinger linger;
     PRMcastRequest add_member;
     PRMcastRequest drop_member;
     PRNetAddr mcast_if;
  } value;
} PRSocketOptionData;
```

### Fields

The structure has the following fields:

`ip_ttl`

: IP time-to-live.

`mcast_ttl`

: IP multicast time-to-live.

`tos`

: IP type-of-service and precedence.

`non_blocking`

: Nonblocking (network) I/O.

`reuse_addr`

: Allow local address reuse.

`keep_alive`

: Periodically test whether connection is still alive.

`mcast_loopback`

: IP multicast loopback.

`no_delay`

: Disable Nagle algorithm. Don't delay send to coalesce packets.

`max_segment`

: TCP maximum segment size.

`recv_buffer_size`

: Receive buffer size.

`send_buffer_size`

: Send buffer size.

`linger`

: Time to linger on close if data are present in socket send buffer.

`add_member`

: Join an IP multicast group.

`drop_member`

: Leave an IP multicast group.

`mcast_if`

: IP multicast interface address.

### Description

{ref}`PRSocketOptionData` is a name-value pair for a socket option. The
`option` field (of enumeration type {ref}`PRSockOption`) specifies the
name of the socket option, and the `value` field (a union of all
possible values) specifies the value of the option.