SOCKET基本知识(1)

 bind Function----The bind function associates a local address with a socket.

int bind(
  __in  SOCKET s,
  __in  const struct sockaddr *name,
  __in  int namelen
);

parameter:

s [in]

A descriptor identifying an unbound socket.

name [in]

A pointer to a sockaddr structure of the local address to assign to the bound socket .

namelen [in]

The length, in bytes, of the value pointed to by the name parameter.

return value:

If no error occurs, bind returns zero. Otherwise, it returns SOCKET_ERROR, and a specific error code can be retrieved by calling WSAGetLastError.

listen Function ----The listen function places a socket in a state in which it is listening for an incoming connection.

int listen(
  __in  SOCKET s,
  __in  int backlog
);

parameter:

s [in]

A descriptor identifying a bound, unconnected socket.

backlog [in]

The maximum length of the queue of pending connections. If set to SOMAXCONN, the underlying service provider responsible for socket s will set the backlog to a maximum reasonable value. There is no standard provision to obtain the actual backlog value.

return value

If no error occurs, listen returns zero. Otherwise, a value of SOCKET_ERROR is returned, and a specific error code can be retrieved by calling WSAGetLastError.

accept ---This function permits an incoming connection attempt on a socket.

SOCKET accept(
  SOCKET s,
  struct sockaddr FAR* addr,
  int FAR* addrlen
);

parameters:

s

[in] Descriptor identifying a socket that has been placed in a listening state with the listen function. The connection is actually made with the socket that is returned by this function.

addr

[out] Optional pointer to a buffer that receives the address of the connecting entity, as known to the communications layer. The exact format of the addr parameter is determined by the address family established when the socket was created.

addrlen

[out] Optional pointer to an integer that contains the length of addr.

return value

If no error occurs, this function returns a value of type SOCKET that is a descriptor for the new socket. This returned value is a handle for the socket on which the actual connection is made.

The integer referred to by addrlen initially contains the amount of space pointed to by addr. On return, it will contain the actual length in bytes of the address returned.

If an error occurs, a value of INVALID_SOCKET is returned, and a specific error code can be retrieved by calling WSAGetLastError. The following table shows the possible error code return values.

send function------The send function sends data on a connected socket.

int send(
  __in  SOCKET s,
  __in  const char *buf,
  __in  int len,
  __in  int flags
);

parameter:

s [in]

A descriptor identifying a connected socket.

buf [in]

A pointer to a buffer containing the data to be transmitted.

len [in]

The length, in bytes, of the data in buffer pointed to by the buf parameter.

flags [in]

A set of flags that specify the way in which the call is made. This parameter is constructed by using the bitwise OR operator with any of the following values.

ValueMeaning

MSG_DONTROUTE

Specifies that the data should not be subject to routing. A Windows Sockets service provider can choose to ignore this flag.

MSG_OOB

Sends OOB data (stream-style socket such as SOCK_STREAM only.

return value

If no error occurs, send returns the total number of bytes sent, which can be less than the number requested to be sent in the len parameter. Otherwise, a value of SOCKET_ERROR is returned, and a specific error code can be retrieved by calling WSAGetLastError.

The send function is used to write outgoing data on a connected socket.

recv----The recv function receives data from a connected socket or a bound connectionless socket.

 int recv(
  __in   SOCKET s,
  __out  char *buf,
  __in   int len,
  __in   int flags
);