BSD Socket API¶

Header File¶

#include <sys/socket.h>

Functions¶

int socket(int domain, int type, int protocol)¶

Create an endpoint for communication

Parameters

domain – [in] Communication domain, Must be AF_INET
type – [in] Socket type SOCK_STREAM or SOCK_DGRAM
protocol – [in] Protocol type, 0 for auto-select

Returns

On success, a file descriptor for the new socket is returned. On error, -1 is returned, and errno is set appropriately.

int connect(int sockfd, const struct sockaddr *addr, socklen_t addrlen)¶

Initiate a connection socket

Parameters

sockfd – [in] Socket file descriptor
addr – [in] Socket address
addrlen – [in] Size of addr

Returns

If the connection or binding succeeds, zero is returned. On error, -1 is returned, and errno is set appropriately.

int send(int sockfd, const void *buf, size_t len, int flags)¶

Send data on a connected socket

Parameters

sockfd – [in] Socket file descriptor
buf – [in] data buffer to send
len – [in] size of data to send
flags – [in] Flags can be MSG_DONTWAIT for non-blocking operation or 0 for no flags

Returns

On success, return the number of bytes sent. On error, -1 is returned, and errno is set appropriately.

int sendto(int sockfd, const void *buf, size_t len, int flags, const struct sockaddr *dest_addr, socklen_t addrlen)¶

Send data to node. This function is used to send data on datagram socket.

Parameters

sockfd – [in] Socket file descriptor
buf – [in] data buffer to send
len – [in] size of data to send
flags – [in] Flags can be MSG_DONTWAIT for non-blocking operation or 0 for no flags
dest_addr – [in] Destination socket address
addrlen – [in] Sizeof dest_addr

Returns

On success, return the number of bytes sent. On error, -1 is returned, and errno is set appropriately.

int recv(int sockfd, void *buf, size_t len, int flags)¶

Receive data from connected socket

Parameters

sockfd – [in] Socket file descriptor
buf – [out] Pointer to buffer to store received data
len – [in] requested length of data to read
flags – [in] Flags can be MSG_DONTWAIT for non-blocking operation or 0 for no flags

Returns

On success, return the number of bytes received. On error, -1 is returned, and errno is set appropriately.

int recvfrom(int sockfd, void *buf, size_t len, int flags, struct sockaddr *src_addr, socklen_t *addrlen)¶

Receive data from node. This function is used to receive data from datagram socket

Parameters

sockfd – [in] Socket file descriptor
buf – [out] Pointer to buffer to store received data
len – [in] Requested length of data
flags – [in] Flags can be MSG_DONTWAIT for non-blocking operation or 0 for no flags
src_addr – [out] Source address of node
addrlen – [out] Length of src_addr

Returns

On success, return the number of bytes received. On error, -1 is returned, and errno is set appropriately.

int getsockopt(int sockfd, int level, int optname, void *optval, socklen_t *optlen)¶

Get socket option

Parameters

sockfd – [in] Socket file descriptor
level – [in] Socket API level (SOL_SOCKET only)
optname – [in] Name of option
optval – [out] Buffer to store option value
optlen – [out] length of optval buffer, value is updated with actual size of optval

Returns

On success, zero is returned for the standard options. On error, -1 is returned, and errno is set appropriately.

int setsockopt(int sockfd, int level, int optname, const void *optval, socklen_t optlen)¶

Set socket option

Parameters

sockfd – [in] Socket file descriptor
level – [in] Socket API level (SOL_SOCKET only)
optname – [in] Name of option
optval – [in] buffer containing value of option
optlen – [in] sizeof optval

Returns

On success, zero is returned for the standard options. On error, -1 is returned, and errno is set appropriately.

Structures¶

struct linger¶

Public Members

int l_onoff¶: option on/off

int l_linger¶: linger time in seconds

struct sockaddr_in¶

IPv4 Socket address structure

Public Members

uint8_t sin_len¶: Length of structure

sa_family_t sin_family¶: Address family (AF_INET only)

in_port_t sin_port¶: Port in network byte order

struct in_addr sin_addr¶: IPv4 address

char sin_zero[8]¶: reserved

struct sockaddr_in6¶

Public Members

uint8_t sin6_len¶: length of this structure

sa_family_t sin6_family¶: AF_INET6

in_port_t sin6_port¶: Transport layer port #

uint32_t sin6_flowinfo¶: IPv6 flow information

struct in6_addr sin6_addr¶: IPv6 address

uint32_t sin6_scope_id¶: Set of interfaces for scope

struct sockaddr¶

Generic socket address structure

Public Members

unsigned char sa_len¶: total length

sa_family_t sa_family¶: address family

char sa_data[14]¶: actually longer; address value

Macros¶

PF_UNSPEC¶: Protocol family unspecified

PF_INET¶: Internet address family (TCP, UDP)

PF_INET6¶: Internet address family V6

AF_UNSPEC¶: BSD address family

AF_INET¶: Internet address family (TCP, UDP)

AF_INET6¶: Internet address family V6

SOCK_STREAM¶: Stream socket type (TCP/connection oriented)

SOCK_DGRAM¶: Datagram socket (UDP/connection-less)

SOCK_NONBLOCK¶: Socket type non-blocking, This flag can be ORed with socket type to specify non-blocking operation of socket. This is to prevent extra call to fcntl

IPPROTO_TCP¶: TCP protocol

IPPROTO_UDP¶: UDP protocol

SOL_SOCKET¶: Socket level

SO_TYPE¶: Get socket type

SO_SNDBUF¶: Get send buffer size

SO_RCVBUF¶: Get receive buffer size

SO_KEEPALIVE¶: Get/set keep alive status

SO_LINGER¶: get/set linger structure

SO_RCVTIMEO¶: Set/get receive timeout

SO_SNDTIMEO¶: set/get send timeout

SO_CONTIMEO¶: set/get connection timeout

TCP_NODELAY¶: Enable/Disable Nagle algorithm

TCP_MAXSEG¶: Get max segment size

TCP_QUICKACK¶: Get Quickack mode status

IP_TTL¶: Get/Set TTL value

MSG_DONTWAIT¶: Nonblocking i/o for this operation only

Type Definitions¶

typedef uint8_t sa_family_t¶

typedef __socklen_t socklen_t¶