Creates a socket. Currently NOTE: errno is not supported by the Sockets Library. Use ErrorLib. Binds a socket to a local port and/or IP address. Either the port or the IP address in the 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 Note that the second argument to 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. Connects a socket to a remote host on a given port. If this is a Note that the second argument to If the bit corresponding to a socket in an Currently only the If If If the function is called with The correct way to change a flag on a socket is as illustrated in the following example: Getting the current flags and modifying them avoids the potential error of clearing other flags. Note: the corresponding BSD call, Reads data from the socket into The socket must be connected. Note: the standard library call Writes data to the socket from The socket must be connected. The The Each Upon successful completion, The socket must be connected. The The Each The socket must be connected. This function is similiar to The socket must be connected. Similiar to The socket must be connected. Reads data from the remote host specified by Note that Writes data the remote host specified by Note that
BSD Sockets API
int socket (int family, int type, int protocol);
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 beSOCK_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.int socket_bind (int sockFD, const struct sockaddr *myAddr, int addrLength);
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
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.socket_bind()
is actually a struct sockaddr_in*
which is cast to the more generalstruct sockaddr*
because internet addresses are used by the Socket Library.int socket_connect (int sockFD, struct sockaddr *servAddr, int addrLength);
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.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.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.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).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.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.command
equal to F_SETFL
it will replace the socket's flags with those specified by flags.
flags = socket_fcntl(sockfd, F_GETFL, 0);
flags |= O_NONBLOCK;
err = socket_fcntl(sockfd, F_SETFL, flags);socket_fcntl()
returns 0 on success and -1 on failure. If -1 is returned, call GetMITLibError()
to get the error code.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);
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()
.read()
is not supported for sockets.int socket_write (int sockFD, void *buffer, UInt32 numBytes);
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.int socket_readv (int sockFD, struct iovec *iov, UInt32 iovCount);
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
.iovec
structure contains the following members:caddr_t iov_base;
int iov_len;
iovec
entry specifies the base address and length of an area in memory where data should be placed. Thesocket_readv()
function always fills an area completely before proceeding to the next.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 andGetMITLibError()
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.int socket_writev (int sockFD, struct iovec *iov, UInt32 iovCount);
socket_writev()
function performs the same action as socket_write()
, but gathers the output data from theiovcnt
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
.iovec
structure contains the following members:caddr_t iov_base;
int iov_len;
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.int socket_recv (int sockFD, void *buffer, UInt32 numBytes, int flags);
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.int socket_send (int sockFD, void *buffer, UInt32 numBytes, int flags);
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
, thensocket_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.int socket_recvfrom (int sockFD, void *buffer, UInt32 numBytes, int flags, struct sockaddr *fromAddr, socklen_t *addrLength);
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 toMSG_DONTWAIT
, then socket_recvfrom()
will not block waiting for data.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);
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.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