NET

Overview

Provides functions and data structures related to network operations.

Since:

1.0

Version:

1.0

Summary

Files

File Name	Description
inet.h	Provides functions and data structures related to network operations.
ifaddrs.h	Provides functions and data structures related to network operations.
if.h	Provides functions and data structures related to network operations. For example, you can use the functions to send and receive network data, manage network addresses, and convert bytes.
netdb.h	Provides functions and data structures related to network operations. For example, you can use the functions to send and receive network data, manage network addresses, and convert bytes.
ether.h	Provides functions and data structures related to network operations. For example, you can use the functions to send and receive network data, manage network addresses, and convert bytes.
resolv.h	Provides functions and data structures related to network operations. For example, you can use the functions to send and receive network data, manage network addresses, and convert bytes.
socket.h	Provides functions and data structures related to network operations.

Data Structures

Data Structure Name	Description
ifaddrs	Defines the network interface information.
if_nameindex	Defines the network adapter information.
hostent	Describes the host name and address information.
sockaddr	Describes the socket address information.

Macros

Macro Name and Value	Description
h_addr h_addr_list[0]	Defines the first address in h_addr_list for backward compatibility.
SOL_SOCKET 1	Defines options for socket level.

Functions

Function Name	Description
htonl (uint32_t n)	uint32_t Converts an integer from the host byte order to the network byte order.
htons (uint16_t n)	uint16_t Converts a 16-bit integer from the host byte order to the network byte order.
ntohl (uint32_t n)	uint32_t Converts an integer from the network byte order to the host byte order.
ntohs (uint16_t n)	uint16_t Converts a 16-bit integer from the network byte order to the host byte order.
inet_addr (const char p)	in_addr_t Converts a string from the IPv4 numbers-and-dots notation to the binary data in network byte order.
inet_network (const char p)	in_addr_t Converts a string from the IPv4 numbers-and-dots notation to the binary data in host byte order.
inet_ntoa (struct in_addr in)	char Converts a network address to a string in dotted-decimal format.
inet_pton (int af, const char restrict s, void *restrict a0)	int Converts a string to a network address in the specified address family.
inet_ntop (int af, const void restrict a0, char restrict s, socklen_t l)	const char Converts a network address in the specified address family to a string.
inet_aton (const char s0, struct in_addr dest)	int Converts an IP address from the string format to the 32-bit binary format in network byte order.
inet_makeaddr (in_addr_t n, in_addr_t h)	struct in_addr Converts the network number and host address to the network address.
inet_lnaof (struct in_addr in)	in_addr_t Converts an IP address into a host ID in host byte order without network bits.
inet_netof (struct in_addr in)	in_addr_t Extracts the network number from the in_addr structure and converts it to the host byte order.
freeifaddrs (struct ifaddrs ifp)	void Frees the network interface information obtained by getifaddrs.
if_freenameindex (struct if_nameindex idx)	void Frees the network adapter information obtained by if_nameindex.
setprotoent (int stayopen)	void Opens a connection to the database and sets the next entry to the first entry.
getprotoent (void)	struct protoent Retrieves the current protocol information.
getprotobyname (const char name)	struct protoent Retrieves the information about a specified protocol.
getprotobynumber (int num)	struct protoent Retrieves the information about a protocol with the specified number.
herror (const char msg)	void Prints error information.
hstrerror (int ecode)	const char Retrieves error information associated with the specified error number.
ether_ntoa (const struct ether_addr p_a)	char Converts binary data in network byte order into a standard 48-bit Ethernet host address in the colon hexadecimal notation.
ether_aton (const char x)	struct ether_addr Converts a standard 48-bit Ethernet host address in the colon hexadecimal notation into binary data in network byte order.
ether_ntoa_r (const struct ether_addr p_a, char x)	char Converts binary data in network byte order into a standard 48-bit Ethernet host address in the colon hexadecimal notation. This function is reentrant.
ether_aton_r (const char x, struct ether_addr p_a)	struct ether_addr Converts a standard 48-bit Ethernet host address in the colon hexadecimal notation into binary data in network byte order. This function is reentrant.
dn_comp (const char src, unsigned char dst, int space, unsigned char dnptrs, unsigned char* lastdnptr)*	int Compresses a network domain name.
dn_expand (const unsigned char base, const unsigned char end, const unsigned char src, char dest, int space)	int Expands a compressed domain name to a full domain name.
socket (int domain, int type, int protocol)	int Creates a socket and returns its descriptor.
shutdown (int sockfd, int how)	int Shuts down a socket.
bind (int sockfd, const struct sockaddr addr, socklen_t addrlen)	int Binds a local protocol address to a socket.
connect (int sockfd, const struct sockaddr addr, socklen_t addrlen)	int Initiates a connection to a socket.
listen (int sockfd, int backlog)	int Listens for network connections.
accept (int sockfd, struct sockaddr restrict addr, socklen_t *restrict addrlen)	int Accepts incoming connection requests.
getsockname (int fd, struct sockaddr restrict addr, socklen_t restrict len)	int Retrieves the local address of the specified socket.
getpeername (int fd, struct sockaddr restrict addr, socklen_t restrict len)	int Retrieves the peer address of the specified socket.
send (int fd, const void buf, size_t len, int flags)	ssize_t Sends data to another socket.
recv (int fd, void buf, size_t len, int flags)	ssize_t Receives data from another socket.
sendto (int fd, const void buf, size_t len, int flags, const struct sockaddr addr, socklen_t alen)	ssize_t Sends data to another socket.
recvfrom (int fd, void __restrict buf, size_t len, int flags, struct sockaddr restrict addr, socklen_t *restrict alen)	ssize_t Receives data from a specified socket.
sendmsg (int fd, const struct msghdr msg, int flags)	ssize_t Sends data to another socket.
recvmsg (int fd, struct msghdr msg, int flags)	ssize_t Receives data from a specified socket.
getsockopt (int fd, int level, int optname, void __restrict optval, socklen_t __restrict optlen)	int Retrieves the socket options.
setsockopt (int fd, int level, int optname, const void *optval, socklen_t optlen)	int Sets the socket options.

Details

Function Documentation

accept()

int accept (int sockfd, struct [sockaddr]($api-api-SmartVision-Devices-sockaddr.md) *__restrict addr, socklen_t *__restrict addrlen )

Description:

Accepts incoming connection requests.

Parameters:

Name	Description
sockfd	Indicates the socket descriptor.
addr	Indicates the pointer to the socket address requiring for the connection.
addrlen	Indicates the length of the address structure pointed to by addr.

Returns:

Returns a valid socket if the operation is successful; returns -1 and sets errno to a value in the following table if the operation fails.

errno	Description
EINVAL	Invalid input parameter
EOPNOTSUPP	The socket requiring for the connection is not of the NETCONN_TCP type.
EWOULDBLOCK	Failure to receive events in non-blocking mode.
ENFILE	Failure to creat a new socket.
ECONNABORTED	Failure to receive the remote information.
ENOMEM	Memory copy exception.

bind()

int bind (int sockfd, const struct [sockaddr]($api-api-SmartVision-Devices-sockaddr.md) * addr, socklen_t addrlen )

Description:

Binds a local protocol address to a socket.

Parameters:

Name	Description
sockfd	Indicates the socket descriptor.
addr	Indicates the address to be bound to the socket.
addrlen	Indicates the length of the address structure pointed to by addr.

Returns:

Returns 0 if the operation is successful; returns -1 and sets errno to a value in the following table if the operation fails.

errno	Description
EINVAL	Invalid input parameter

connect()

int connect (int sockfd, const struct [sockaddr]($api-api-SmartVision-Devices-sockaddr.md) * addr, socklen_t addrlen )

Description:

Initiates a connection to a socket.

Parameters:

Name	Description
sockfd	Indicates the socket descriptor.
addr	Indicates the pointer to the address to be connected.
addrlen	Indicates the length of the address structure pointed to by addr.

Returns:

Returns 0 if the operation is successful; returns -1 and sets errno to a value in the following table if the operation fails.

errno	Description
EINVAL	Invalid input parameter
EBADF	Invalid socket or socket status exception
EIO	Incorrect connection type obtained based on the socket descriptor
ECONNREFUSED	Restart due to connection failure
ECONNABORTED	Shut-down due to connection failure

dn_comp()

int dn_comp (const char * src, unsigned char * dst, int space, unsigned char ** dnptrs, unsigned char ** lastdnptr )

Description:

Compresses a network domain name.

To reduce the size of DNS messages, domain names in the messages are compressed. For details about the compression scheme, see RFC 1035.

Parameters:

Name	Description
src	Indicates the pointer to the domain name to be compressed.
dst	Indicates the pointer to the compressed domain name.
space	Indicates the size of the compressed domain name.
dnptrs	Indicates the pointer to an array of pointers to previously compressed domain names. If the value is NULL, the current domain name will not be compressed.
lastdnptr	Indicates the pointer to the last element of the array. If the value is NULL, the array is not updated.

Returns:

Returns the length of the compressed domain name if the operation is successful; returns -1 otherwise.

dn_expand()

int dn_expand (const unsigned char * base, const unsigned char * end, const unsigned char * src, char * dest, int space )

Description:

Expands a compressed domain name to a full domain name.

The compressed domain name is contained in a query or reply message.

Parameters:

Name	Description
base	Indicates the pointer to the start of the DNS message body.
end	Indicates the pointer to the end of the DNS message body.
src	Indicates the pointer to the compressed domain name.
dest	Indicates the pointer to the expanded domain name.
space	Indicates the memory size of the dest address.

Returns:

Returns the length of the compressed domain name if the operation is successful; returns -1 otherwise.

ether_aton()

struct ether_addr* ether_aton (const char * x)

Description:

Converts a standard 48-bit Ethernet host address in the colon hexadecimal notation into binary data in network byte order.

Parameters:

Name	Description
x	Indicates the pointer to the host address to be converted.

Returns:

Returns the binary data if the operation is successful; returns 0 otherwise.

ether_aton_r()

struct ether_addr* ether_aton_r (const char * x, struct ether_addr * p_a )

Description:

Converts a standard 48-bit Ethernet host address in the colon hexadecimal notation into binary data in network byte order. This function is reentrant.

This function is used in multitasking scenarios.

Parameters:

Name	Description
x	Indicates the pointer to the host address to be converted.
p_a	Indicates the pointer to the temporary buffer during conversion.

Returns:

Returns the binary data represented by ether_addr if the operation is successful; returns 0 otherwise.

ether_ntoa()

char* ether_ntoa (const struct ether_addr * p_a)

Description:

Converts binary data in network byte order into a standard 48-bit Ethernet host address in the colon hexadecimal notation.

Parameters:

Name	Description
p_a	Indicates the pointer to the binary data to be converted.

Attention:

Different from glibc (for example, 1:2:3:4:5:f), 0 is prefixed and letters are capitalized (for example, 01:02:03:04:05:0F).

Returns:

Returns the host address if the operation is successful; returns 0 otherwise.

ether_ntoa_r()

char* ether_ntoa_r (const struct ether_addr * p_a, char * x )

Description:

Converts binary data in network byte order into a standard 48-bit Ethernet host address in the colon hexadecimal notation. This function is reentrant.

This function is used in multitasking scenarios.

Parameters:

Name	Description
p_a	Indicates the pointer to the binary data to be converted.
x	Indicates the pointer to the temporary buffer during conversion.

Attention:

Different from glibc (for example, 1:2:3:4:5:f), 0 is prefixed and letters are capitalized (for example, 01:02:03:04:05:0F).

Returns:

Returns the host address if the operation is successful; returns 0 otherwise.

freeifaddrs()

void freeifaddrs (struct [ifaddrs]($api-api-SmartVision-Devices-ifaddrs.md) * ifp)

Description:

Frees the network interface information obtained by getifaddrs.

Parameters:

Name	Description
ifp	Indicates the pointer to the network interface information to be freed.

getpeername()

int getpeername (int fd, struct [sockaddr]($api-api-SmartVision-Devices-sockaddr.md) *restrict addr, socklen_t *restrict len )

Description:

Retrieves the peer address of the specified socket.

Parameters:

Name	Description
fd	Indicates the socket descriptor.
addr	Indicates the pointer to the address to be retrieved.
len	Indicates the pointer to the length of the address pointed to by addr.

Returns:

Returns 0 if the operation is successful; returns -1 and sets errno to a value in the following table if the operation fails.

errno	Description
EINVAL	Invalid input parameter
EBADF	Invalid socket or socket status exception
ENOMEM	Memory copy exception

getprotobyname()

struct protoent* getprotobyname (const char * name)

Description:

Retrieves the information about a specified protocol.

Parameters:

Name	Description
addr	Indicates the pointer to the protocol name.

Attention:

The /etc/protocols configuration file is not supported. Only the following built-in protocols are supported: ip/icmp/igmp/ggp/ipencap/st/tcp/egp/pup/udp/hmp/xns-idp/rdp/iso-tp4/xtp/ ddp/idpr-cmtp/ipv6/ipv6-route/ipv6-frag/idrp/rsvp/gre/esp/ah/skip/ipv6-icmp/ ipv6-nonxt/ipv6-opts/rspf/vmtp/ospf/ipip/encap/pim/raw (This protocol does not have the aliases attribute, that is, aliases is empty.)

Returns:

Returns the protocol information if the operation is successful; returns NULL otherwise.

getprotobynumber()

struct protoent* getprotobynumber (int num)

Description:

Retrieves the information about a protocol with the specified number.

Parameters:

Name	Description
num	Indicates the protocol number.

Attention:

Returns:

Returns the protocol information if the operation is successful; returns NULL otherwise.

getprotoent()

struct protoent* getprotoent (void )

Description:

Retrieves the current protocol information.

Attention:

Returns:

Returns the protocol information if the operation is successful; returns NULL otherwise.

getsockname()

int getsockname (int fd, struct [sockaddr]($api-api-SmartVision-Devices-sockaddr.md) *restrict addr, socklen_t *restrict len )

Description:

Retrieves the local address of the specified socket.

Parameters:

Name	Description
fd	Indicates the socket descriptor.
addr	Indicates the pointer to the address to be retrieved.
len	Indicates the pointer to the length of the address pointed to by addr.

Returns:

Returns 0 if the operation is successful; returns -1 and sets errno to a value in the following table if the operation fails.

errno	Description
EINVAL	Invalid input parameter
EBADF	Invalid socket or socket status exception
ENOMEM	Memory copy exception

getsockopt()

int getsockopt (int fd, int level, int optname, void *__restrict optval, socklen_t *__restrict optlen )

Description:

Retrieves the socket options.

Parameters:

Name	Description
fd	Indicates the socket descriptor.
level	Indicates the protocol level at which the option resides. Only SOL_SOCKET is supported.
optname	Indicates the socket options to be retrieved, which has the following values:
optval	Indicates the pointer to the option data.
optlen	Indicates the pointer to the size of the buffer pointed to by optval.

value	Description
SO_BROADCAST	Permits sending broadcast messages.
SO_RCVTIMEO	Receiving data times out.
SO_RCVBUF	Sets or gets the maximum socket receiving buffer in bytes.
SO_TYPE	Gets the socket type.
SO_DONTROUTE	Prohibits messages from being sent via a gateway.
SO_BINDTODEVICE	Binds this socket to a particular device.

Returns:

Returns 0 if the operation is successful; returns -1 and sets errno to a value in the following table if the operation fails.

errno	Description
EINVAL	Small optlen
EBADF	Invalid socket or socket status exception
EFAULT	The input parameter is a null pointer.
ENOBUFS	Retrieved length exception
ENOMEM	Memory copy exception

herror()

void herror (const char * msg)

Description:

Prints error information.

Parameters:

Name	Description
msg	Indicates the pointer to the string to be printed together with the error information. This parameter can be null.

Returns:

Returns 0 if the operation is successful; returns -1 and sets errno to a value in the following table if the operation fails.

errno	Description
EINVAL	Incorrect symbols or parameters
EOVERFLOW	Long item for printing

hstrerror()

const char* hstrerror (int ecode)

Description:

Retrieves error information associated with the specified error number.

Parameters:

Name	Description
ecode	Indicates the error number.

Returns:

Returns the string representing the error information.

htonl()

uint32_t htonl (uint32_t n)

Description:

Converts an integer from the host byte order to the network byte order.

Parameters:

Name	Description
n	Indicates the integer in host byte order.

Returns:

Returns the original data if the system is in big-endian mode; returns the converted data otherwise.

htons()

uint16_t htons (uint16_t n)

Description:

Converts a 16-bit integer from the host byte order to the network byte order.

Parameters:

Name	Description
n	Indicates the integer in host byte order.

Returns:

Returns the original data if the system is in big-endian mode; returns the converted data otherwise.

if_freenameindex()

void if_freenameindex (struct [if_nameindex]($api-api-SmartVision-Devices-if_nameindex.md) * idx)

Description:

Frees the network adapter information obtained by if_nameindex.

Parameters:

Name	Description
idx	Indicates the pointer to the network adapter to be freed.

inet_addr()

in_addr_t inet_addr (const char * p)

Description:

Converts a string from the IPv4 numbers-and-dots notation to the binary data in network byte order.

Parameters:

Name	Description
p	Indicates the pointer to the string to be converted.

Returns:

Returns the converted data if the operation is successful; returns -1 otherwise.

inet_aton()

int inet_aton (const char * s0, struct in_addr * dest )

Description:

Converts an IP address from the string format to the 32-bit binary format in network byte order.

Parameters:

Name	Description
s0	Indicates the pointer to the IP address to be converted.
dest	Indicates the pointer to the structure for conversion.

Returns:

Returns 1 if the operation is successful; returns 0 otherwise.

inet_lnaof()

in_addr_t inet_lnaof (struct in_addr in)

Description:

Converts an IP address into a host ID in host byte order without network bits.

Parameters:

Name	Description
in	Indicates the network address structure.

Returns:

Returns the converted host address.

inet_makeaddr()

struct in_addr inet_makeaddr (in_addr_t n, in_addr_t h )

Description:

Converts the network number and host address to the network address.

Parameters:

Name	Description
n	Indicates the network number.
h	Indicates the host address.

Returns:

Returns the converted network address.

inet_netof()

in_addr_t inet_netof (struct in_addr in)

Description:

Extracts the network number from the in_addr structure and converts it to the host byte order.

Parameters:

Name	Description
in	Indicates the network address structure.

Returns:

Returns the converted network number.

inet_network()

in_addr_t inet_network (const char * p)

Description:

Converts a string from the IPv4 numbers-and-dots notation to the binary data in host byte order.

Parameters:

Name	Description
p	Indicates the pointer to the string to be converted.

Returns:

Returns the converted data if the operation is successful; returns -1 otherwise.

inet_ntoa()

char* inet_ntoa (struct in_addr in)

Description:

Converts a network address to a string in dotted-decimal format.

Parameters:

Name	Description
in	Indicates the network address to be converted.

Returns:

Returns the string.

inet_ntop()

const char* inet_ntop (int af, const void *restrict a0, char *restrict s, socklen_t l )

Description:

Converts a network address in the specified address family to a string.

Parameters:

Name	Description
af	Indicates the address family. Currently, only AF_INET and AF_INET6 are supported.
a0	Indicates the pointer to the data to be converted.
s	Indicates the pointer to the string to be converted.
l	Indicates the size of the string to be converted.

Returns:

Returns the converted string if the operation is successful; returns NULL and sets errno to a value in the following table if the operation fails.

errno	Description
ENOSPC	Insufficient space for conversion
EAFNOSUPPORT	Unsupported address family

inet_pton()

int inet_pton (int af, const char *__restrict s, void *__restrict a0 )

Description:

Converts a string to a network address in the specified address family.

Parameters:

Name	Description
af	Indicates the address family. Currently, only AF_INET and AF_INET6 are supported.
s	Indicates the pointer to the string to be converted.
a0	Indicates the pointer to the converted data.

Returns:

Returns 1 if the operation is successful; returns 0 if the input address family is invalid; returns -1 if the operation fails. The error codes are set as follows:

errno	Description
EAFNOSUPPORT	Unsupported address family

listen()

int listen (int sockfd, int backlog )

Description:

Listens for network connections.

Parameters:

Name	Description
sockfd	Indicates the socket descriptor.
backlog	Indicates the maximum length of the queue to accept incoming connection requests.

Returns:

Returns 0 if the operation is successful; returns -1 and sets errno to a value in the following table if the operation fails.

errno	Description
EINVAL	Invalid input parameter
EBADF	Invalid socket or socket status exception
EIO	Incorrect connection type obtained based on the socket descriptor

ntohl()

uint32_t ntohl (uint32_t n)

Description:

Converts an integer from the network byte order to the host byte order.

Parameters:

Name	Description
n	Indicates the integer in network byte order.

Returns:

Returns the original data if the system is in big-endian mode; returns the converted data otherwise.

ntohs()

uint16_t ntohs (uint16_t n)

Description:

Converts a 16-bit integer from the network byte order to the host byte order.

Parameters:

Name	Description
n	Indicates the integer in network byte order.

Returns:

Returns the original data if the system is in big-endian mode; returns the converted data otherwise.

recv()

ssize_t recv (int fd, void * buf, size_t len, int flags )

Description:

Receives data from another socket.

Parameters:

Name	Description
fd	Indicates the socket descriptor.
buf	Indicates the pointer to a buffer for storing the data to be received.
len	Indicates the length of the buffer pointed to by buf.
flags	Indicates the socket flags. This parameter has the following values:

value	Description
MSG_DONTWAIT	Enables the non-blocking operation.
MSG_MORE	The caller has more data to send.
MSG_NOSIGNAL	No signals are generated.

Returns:

Returns the length of the received data if the operation is successful; returns -1 and sets errno to a value in the following table if the operation fails.

errno	Description
EINVAL	Invalid input parameter
EBADF	Invalid socket or socket status exception
ENOMEM	Memory copy exception
EOPNOTSUPP	Unsupported message type
ENOTCONN	Socket not connected
EWOULDBLOCK	Blocking operation
ENOTCONN	Connection closed

recvfrom()

ssize_t recvfrom (int fd, void *__restrict buf, size_t len, int flags, struct [sockaddr]($api-api-SmartVision-Devices-sockaddr.md) *__restrict addr, socklen_t *__restrict alen )

Description:

Receives data from a specified socket.

Parameters:

Name	Description
fd	Indicates the socket descriptor.
buf	Indicates the pointer to a buffer for storing the data to be received.
len	Indicates the length of the buffer pointed to by buf.
flags	Indicates the socket flags. This parameter has the following values:
addr	Indicates the pointer to the source address.
alen	Indicates the size of the source address.

value	Description
MSG_DONTWAIT	Enables the non-blocking operation.
MSG_MORE	The caller has more data to send.
MSG_NOSIGNAL	No signals are generated.

Returns:

Returns the length of the received data if the operation is successful; returns -1 and sets errno to a value in the following table if the operation fails.

errno	Description
EINVAL	Invalid input parameter
EBADF	Invalid socket or socket status exception
ENOMEM	Memory copy exception
EOPNOTSUPP	Unsupported message type
ENOTCONN	Socket not connected
ENOTCONN	Connection closed

recvmsg()

ssize_t recvmsg (int fd, struct msghdr * msg, int flags )

Description:

Receives data from a specified socket.

Parameters:

Name	Description
fd	Indicates the socket descriptor.
msg	Indicates the pointer to the address to receive the message header.
flags	Indicates the socket flags. This parameter has the following values:

value	Description
MSG_DONTWAIT	Enables the non-blocking operation.
MSG_MORE	The caller has more data to send.
MSG_NOSIGNAL	No signals are generated.

Attention:

This function does not allow sending ancillary data. Currently, the length of the array defined by msg_iov can only be 1.

Returns:

Returns the length of the received data if the operation is successful; returns -1 and sets errno to a value in the following table if the operation fails.

errno	Description
EINVAL	Invalid input parameter
EBADF	Invalid socket or socket status exception
EDESTADDRREQ	Invalid connection
ENOMEM	Memory copy exception
EIO	Incorrect connection type obtained based on the socket descriptor

send()

ssize_t send (int fd, const void * buf, size_t len, int flags )

Description:

Sends data to another socket.

Parameters:

Name	Description
fd	Indicates the socket descriptor.
buf	Indicates the pointer to a buffer for storing the data to be sent.
len	Indicates the length of the buffer pointed to by buf.
flags	Indicates the socket flags. This parameter has the following values:

value	Description
MSG_DONTWAIT	Enables the non-blocking operation.
MSG_MORE	The caller has more data to send.
MSG_NOSIGNAL	No signals are generated.

Returns:

Returns the length of the sent data if the operation is successful; returns -1 and sets errno to a value in the following table if the operation fails.

errno	Description
EINVAL	Invalid input parameter
EBADF	Invalid socket or socket status exception
EDESTADDRREQ	Invalid connection
ENOMEM	Memory copy exception
EOPNOTSUPP	Unsupported message type
ENOTCONN	Socket not connected
EIO	Incorrect connection type obtained based on the socket descriptor

sendmsg()

ssize_t sendmsg (int fd, const struct msghdr * msg, int flags )

Description:

Sends data to another socket.

Parameters:

Name	Description
fd	Indicates the socket descriptor.
msg	Indicates the pointer to the address of the message header to be sent.
flags	Indicates the socket flags. This parameter has the following values:

value	Description
MSG_DONTWAIT	Enables the non-blocking operation.
MSG_MORE	The caller has more data to send.
MSG_NOSIGNAL	No signals are generated.

Attention:

This function does not support ancillary data.

Returns:

Returns the length of the sent data if the operation is successful; returns -1 and sets errno to a value in the following table if the operation fails.

errno	Description
EINVAL	Invalid input parameter
EBADF	Invalid socket or socket status exception
EDESTADDRREQ	Invalid connection
ENOMEM	Memory copy exception
EIO	Incorrect connection type obtained based on the socket descriptor
EOPNOTSUPP	Unsupported message type

sendto()

ssize_t sendto (int fd, const void * buf, size_t len, int flags, const struct [sockaddr]($api-api-SmartVision-Devices-sockaddr.md) * addr, socklen_t alen )

Description:

Sends data to another socket.

Parameters:

Name	Description
fd	Indicates the socket descriptor.
buf	Indicates the pointer to a buffer for storing the data to be sent.
len	Indicates the length of the buffer pointed to by buf.
flags	Indicates the socket flags. This parameter has the following values:
addr	Indicates the pointer to the destination network address.
alen	Indicates the length of the destination network address.

value	Description
MSG_DONTWAIT	Enables the non-blocking operation.
MSG_MORE	The caller has more data to send.
MSG_NOSIGNAL	No signals are generated.

Returns:

Returns the length of the sent data if the operation is successful; returns -1 and sets errno to a value in the following table if the operation fails.

errno	Description
EINVAL	Invalid input parameter
EBADF	Invalid socket or socket status exception
EDESTADDRREQ	Invalid connection
ENOMEM	Memory copy exception
EOPNOTSUPP	Unsupported message type
ENOTCONN	Socket not connected
EIO	Incorrect connection type obtained based on the socket descriptor

setprotoent()

void setprotoent (int stayopen)

Description:

Opens a connection to the database and sets the next entry to the first entry.

Parameters:

Name	Description
stayopen	Reserved for interface compatibility (not used currently).

Attention:

The stayopen parameter does not take effect. It is equivalent to nonzero for getprotoent and zero for getprotobyname and getprotobynumbmer.

setsockopt()

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

Description:

Sets the socket options.

Parameters:

Name	Description
fd	Indicates the socket descriptor.
level	Indicates the protocol level at which the option resides. Only SOL_SOCKET is supported.
optname	Indicates the socket options to set, which has the following values:
optval	Indicates the pointer to the option data.
optlen	Indicates the size of the buffer pointed to by optval.

value	Description
SO_BROADCAST	Permits sending broadcast messages.
SO_RCVTIMEO	Receiving data times out.
SO_RCVBUF	Sets or gets the maximum socket receiving buffer in bytes.
SO_DONTROUTE	Prohibits messages from being sent via a gateway.
SO_BINDTODEVICE	Binds this socket to a particular device.

Returns:

Returns 0 if the operation is successful; returns -1 and sets errno to a value in the following table if the operation fails.

errno	Description
EINVAL	Small optlen
EBADF	Invalid socket or socket status exception
EFAULT	The input parameter is a null pointer.
ENOBUFS	Retrieved length exception
ENOMEM	Memory copy exception

shutdown()

int shutdown (int sockfd, int how )

Description:

Shuts down a socket.

Parameters:

Name	Description
sockfd	Indicates the socket descriptor.
how	Indicates how to shut down the socket. You can disable either receptions by SHUT_RD or transmissions by SHUT_WR, or both by SHUT_RDWR.

Returns:

Returns 0 if the operation is successful; returns -1 and sets errno to a value in the following table if the operation fails.

errno	Description
EINVAL	Invalid input parameter
ENOTCONN	Socket not connected
ENOMEM	Memory copy exception
EIO	Incorrect connection type obtained based on the socket descriptor

socket()

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

Description:

Creates a socket and returns its descriptor.

Parameters:

Name	Description
domain	Indicates the socket domain.
type	Indicates the socket type.
protocol	Indicates the socket protocol.

Attention:

Only the following socket domains are supported: AF_INET, AF_INET6. Only the socket types SOCK_RAW, SOCK_DGRAM and SOCK_STREAM are supported, and the OR operation between the extra socket flag and the socket type is not supported.

Returns:

Returns the descriptor for the new socket if the operation is successful; returns -1 and sets errno to a value in the following table if the operation fails.

errno	Description
EAFNOSUPPORT	Invalid socket domain
ESOCKTNOSUPPORT	Unsupported socket domain
EPROTONOSUPPORT	Unsupported protocol
EINVAL	Invalid input parameter
ENOBUFS	Connection setup error
ENFILE	File table addition exception