s不是结构体。就4字节的一变量。

typedef _W64 unsigned int UINT_PTR, *PUINT_PTR;
typedef UINT_PTR SOCKET;

int PASCAL FAR getpeername (
IN SOCKET s,
OUT struct sockaddr FAR *name,
IN OUT int FAR * namelen);

getsockname 获取本地的socket地址信息
getpeername 获取连接上来的客户端地址信息

getsockname
The getsockname function retrieves the local name for a socket.

int getsockname(
  SOCKET s,
  struct sockaddr* name,
  int* namelen
);

Parameters
s
[in] Descriptor identifying a socket.
name
[out] Pointer to a SOCKADDR structure that receives the address (name) of the socket.
namelen
[in, out] Size of the name buffer, in bytes.

-----------------------
getpeername
The getpeername function retrieves the name of the peer to which a socket is connected.

int getpeername(
  SOCKET s,
  struct sockaddr* name,
  int* namelen
);

Parameters
s
[in] Descriptor identifying a connected socket.
name
[out] The SOCKADDR structure that receives the name of the peer.
namelen
[in, out] Pointer to the size of the name structure, in bytes.

谢谢　pathletboy　和　sojoo

谢谢～