BSD Socket API 函数参考大全

BSD Sockets API

int socket (int
family, int type, int protocol);

Creates a socket. Currently

family

can only be

AF_INET

(OT does not support IPv6 so there is no AF_INET6
support).

protocol

can be

PF_INET

or

PF_UNSPEC

(both have the same effect of creating an internet socket.

type

can
be

SOCK_STREAM

for TCP sockets or

SOCK_DGRAM

for UDP sockets.

socket()

returns a socket file descriptor (

sockFD

) which is a small non-negative integer. This file descriptor
number should be used for all other socket operations on that socket. If

socket()

encounters an error, it will return -1, in which case the application should call

GetMITLibError()

to
get the error code.
NOTE: errno is not supported by the Sockets Library. Use ErrorLib.

int socket_bind (int
sockFD, const struct
sockaddr *myAddr, int addrLength);

Binds a socket to a local port and/or IP address. Either the port or the IP address in the

struct sockaddr

structure may be wildcarded in which case
the library will select appropriate values. To wildcard the port set the

sin_port

field of the address to 0. To wildcard the IP, set the

sin_addr.s_addr

field of the
address to

INADDR_ANY

TCP has a port reuse time limit. If an application attempts to bind to the same local port twice in rapid succession, the second attempt will fail with

EADDRINUSE

.
Just wait and try again.

socket_bind()

returns 0 on success and -1 on failure. If -1 is returned, call

GetMITLibError()

to get the
error code.
Note that the second argument to

socket_bind()

is actually a

struct
sockaddr_in*

which is cast to the more general

struct sockaddr*

because internet addresses are used by the Socket Library.
Also, it is not necessary to bind a socket prior to connecting it. If a socket is not bound the library will choose the local port and IP.

int socket_connect (int
sockFD, struct
sockaddr *servAddr, int addrLength);

Connects a socket to a remote host on a given port. If this is a

SOCK_STREAM

(TCP) socket,

socket_connect()

will
actually perform TCP negotation to open a connection. If this is a

SOCK_DGRAM

(UDP) socket,

socket_connect()

will just store the address for use later with other socket
operations (this is important to note because if

sockFD

refers to a UDP socket, errors will not be reported prior to an attempt to read or write data on the socket).

socket_connect()

returns 0 on success and -1 on failure. If -1 is returned, call

GetMITLibError()

to get
the error code.
Note that the second argument to

connect

is actually a

struct
sockaddr_in*

which is cast to the more general

struct sockaddr*

because internet addresses are used by the Socket Library.

int socket_select (int
maxFDsExamined, fd_set *readFDs, fd_set *writeFDs, fd_set*exceptFDs, struct
timeval *timeOut);

socket_select()

allows for conditions to be checked on one or more sockets.

maxFDsExamined

should be one greater than value of the largest valued socket descriptor in any of the lists. If you don't wish to calculate this, use

FD_SETSIZE

instead.
For small numbers of sockets,

socket_select()

will be less efficient if FD_SETSIZE is passed.
If the bit corresponding to a socket in an

fd_set

is set, that socket will be checked for the condition the

fd_set

corresponds
to. If the condition they are checked for is true, they will still be set to

true

when

socket_select()

returns (otherwise they will be set to false). Note that the sets
are modified by

socket_select()

: thus they must be reset between each call to the function.

fd_set

s can be manipulated using the following macros:

FD_SET(fd, fdset)	Sets socket fd in fdset to true.
FD_CLR(fd, fdset)	Sets socket fd in fdset to false.
FD_ISSET(fd, fdset)	Returns true iff socket fd is set to true in fdset .
FD_ZERO(fdset)	Sets all the sockets in fdset to false.

Currently only the

readfds

condition (whether there is data to read on a socket) is supported. However, in order to stay compatible with most clients,

writefds

(whether
there is room in the kernel buffers to write to a socket) behaves as though writing data will succeed (this is usually fine) and

exceptfds

behaves as though there are no exception conditions on the socket (

exceptfds

will
always be returned with all sockets set to false).
If

timeout

is NULL,

socket_select()

blocks until one of the conditions becomes true for one of the sockets.
If

timeout

is non-NULL,

socket_select()

checks for the amount of time corresponding to

timeout

and then returns (regardless
of whether it has found any conditions to be true). If one of the conditions becomes true for one of the sockets it finds before the timeout has expired, it always returns immediately. To use

socket_select()

in
non-blocking mode call it with a non-null

timeOut

whose

tv_sec

and

tv_usec

fields are both set to zero.

socket_select()

returns the number of sockets for which the specified conditions are true. If it encounters an error, it will return -1 (in which case

GetMITLibError()

can
be called to retrieve the error code.)

int socket_fcntl (int
sockFD, int command, int flags);

socket_fcntl()

sets various options on a socket. Currently the only flag supported is O_NONBLOCK which sets a socket to non-blocking mode.
If

socket_fcntl()

is called with

command

equal to

F_GETFL

it
will return the current flags for the socket

sockFD.

The parameter

flags

is ignored in this case.
If the function is called with

command

equal to

F_SETFL

it will replace the socket's flags with those specified
by

flags.

The correct way to change a flag on a socket is as illustrated in the following example:

flags = socket_fcntl(sockfd, F_GETFL, 0);

flags |= O_NONBLOCK;

err = socket_fcntl(sockfd, F_SETFL, flags);

Getting the current flags and modifying them avoids the potential error of clearing other flags.

socket_fcntl()

returns 0 on success and -1 on failure. If -1 is returned, call

GetMITLibError()

to get
the error code.
Note: the corresponding BSD call,

fcntl

takes a variable number of arguments while

socket_fcntl

does not.

int socket_getpeername (int
sockFD, struct
sockaddr *peerAddr, int *addrLength);

socket_getpeername()

gets the address of the remote host the socket is connected to, if any. If the socket is not connected,

GetMITLibError()

will
return

ENOTCONN

.

socket_getpeername()

returns 0 on success and -1 on failure. If -1 is returned, call

GetMITLibError()

to
get the error code.

int socket_getsockname (int
sockFD, struct
sockaddr *localAddr, int *addrLength);

socket_getsockname()

gets the socket's local address and port.

socket_getsockname()

returns 0 on success and -1 on failure. If -1 is returned, call

GetMITLibError()

to
get the error code.

int socket_read (int
sockFD, void *buffer, UInt32 numBytes);

Reads data from the socket into

buffer

.

numBytes

should be the size of the buffer.

socket_read()

may
not fill the entire buffer.

socket_read()

returns the amount of data which was read. If there is an error, -1 is returned and

GetMITLibError()

can
be called to retrieve the error code. If 0 is returned, this means that the socket received an EOF (the remote host closed the connection gracefully.) To perform a full read on a socket, continue to call

socket_read()

until
the desired number of bytes have been accumulated. Note that

socket_read()

may block if no data is available to be read. This condition can be checked using

socket_select()

.
The socket must be connected.
Note: the standard library call

read()

is not supported for sockets.

int socket_write (int
sockFD, void *buffer, UInt32 numBytes);

Writes data to the socket from

buffer

.

numBytes

should be the amount of data in the buffer.

socket_write()

may
not write out the entire buffer.

socket_write()

returns the amount of data which was written. If there is an error, -1 is returned and

GetMITLibError()

can
be called to get the error code.
The socket must be connected.

int socket_readv (int
sockFD, struct
iovec *iov, UInt32 iovCount);

The

socket_readv()

function is equivalent to

socket_read()

, but places the input data into the

iovcnt

buffers
specified by the members of the

iov

array:

iov0, iov1, ..., iov[iovcnt-1]

. The

iovcnt

argument is valid if greater than 0
and less than or equal to

IOV_MAX

.
The

iovec

structure contains the following members:

caddr_t iov_base;

int iov_len;

Each

iovec

entry specifies the base address and length of an area in memory where data should be placed. The

socket_readv()

function
always fills an area completely before proceeding to the next.
Upon successful completion,

socket_readv()

marks for update the

st_atime

field of the file.

socket_readv()

returns the total amount of data which was read into all buffers. If there is an error, -1 is returned and

GetMITLibError()

can
be called to get the error code. If 0 is returned, this means that the socket got an EOF (the remote host closed the connection gracefully.
The socket must be connected.

int socket_writev (int
sockFD, struct
iovec *iov, UInt32 iovCount);

The

socket_writev()

function performs the same action as

socket_write()

, but gathers the output data from
the

iovcnt

buffers specified by the members of the

iov

array:

iov[0], iov[1], ..., iov[iovcnt-1]

. The

iovcnt

buffer
is valid if greater than 0 and less than or equal to

IOV_MAX

.
The

iovec

structure contains the following members:

caddr_t iov_base;

int iov_len;

Each

iovec

entry specifies the base address and length of an area in memory from which data should be written.

socket_writev()

always
writes all data from an area before proceeding to the next.

socket_writev()

returns the amount of data which was written. If there is an error, -1 is returned and

GetMITLibError()

can
be called to get the error code.
The socket must be connected.

int socket_recv (int
sockFD, void *buffer, UInt32 numBytes, int flags);

This function is similiar to

socket_read()

with the addition of a final parameter.

socket_recv()

reads
data from the socket into

buffer

.

numBytes

should be the size of the buffer.

socket_recv()

may not fill the entire buffer.
If

flags

is set to

MSG_DONTWAIT

, then

socket_recv

will not block if not data is available.

socket_recv()

returns the amount of data which was read. If there is an error, -1 is returned and

GetMITLibError()

can
be called to get the error code. If 0 is returned, this means that the socket received an EOF (the remote host closed the connection gracefully.
The socket must be connected.

int socket_send (int
sockFD, void *buffer, UInt32 numBytes, int flags);

Similiar to

socket_write()

,

socket_send()

writes data to the socket from

buffer

.

numBytes

should
be the amount of data in the buffer.

socket_send()

may not write out the entire buffer. If

flags

is set to

MSG_DONTWAIT

,
then

socket_send()

will not block waiting for buffers to become free.

socket_send()

returns the amount of data which was written. If there is an error, -1 is returned and

GetMITLibError()

can
be called to receive the error code.
The socket must be connected.

int socket_recvfrom (int
sockFD, void *buffer, UInt32 numBytes, int flags, struct
sockaddr *fromAddr, socklen_t *addrLength);

Reads data from the remote host specified by

fromAddr

into

buffer

. The socket must be a

SOCK_DGRAM

(UDP)
socket.

numBytes

should be the size of the buffer.

socket_recvfrom()

may not fill the entire buffer. If

flags

is set to

MSG_DONTWAIT

,
then

socket_recvfrom()

will not block waiting for data.
Note that

fromAddr

will actually be a

struct sockaddr_in*

socket_recvfrom()

returns the amount of data which was read. If there is an error, -1 is returned and

GetMITLibError()

may
be called to get the error code. If 0 is returned, this means that the socket got an EOF (the remote host closed the connection gracefully.

int socket_sendto (int
sockFD, void *buffer, UInt32 numBytes, int flags, struct
sockaddr *toAddr, socklen_t addrLength);

Writes data the remote host specified by

fromAddr

into

buffer

. The socket must be a

SOCK_DGRAM

(UDP)
socket.

numBytes

should be the amount of data in the buffer.

socket_sendto()

may not write out the entire buffer. If

flags

is
set to

MSG_DONTWAIT

, then

socket_sendto()

will not block waiting for buffers to become free.
Note that

toAddr

will actually be a

struct sockaddr_in*

socket_sendto()

returns the amount of data which was written. If there is an error, -1 is returned and

GetMITLibError()

can
be called to get the error code.

int socket_shutdown (int
sockFD, int howTo);

socket_shutdown()

closes one or both directions of a connected socket.

howTo

can be

SHUT_RD

,

SHUT_WR

or

SHUT_RDWR

.

SHUT_RD

tells
it to close the reading side of the connection (reads from the socket will no longer be possible).

SHUT_WR

tells it to close the writing half of the socket (this will cause it to send an orderly disconnect to the
remote host, telling that host it no longer has anything to write).

SHUT_RDWR

tells it to close both halves of the connection (It is still necessary to free the socket with

socket_close()

).

socket_shutdown()

returns 0 on success and -1 on failure. If -1 is returned, call

GetMITLibError()

to get
the error code.

int socket_close (int
sockFD);

socket_close()

frees a socket's resources, disconnecting it from the remote host, if necessary. Both TCP and UDP sockets should be closed with this
function.

socket_close()

returns 0 on success and -1 on failure. If -1 is returned, call

GetMITLibError()

to get
the error code.

来自：http://web.mit.edu/macdev/Development/MITSupportLib/SocketsLib/Documentation/sockets.html

作者：Alexliu（alex
dotNet Learning）


出处：http://alexliu.cnblogs.com/