Mbed OS 文档翻译 之 参考（API（网络套接字（UDPSocket）））

UDPSocket

                                                                                  

                                                                           UDPSocket 类层次结构

UDPSocket 类提供了使用 sendto 和 recvfrom 成员函数通过 UDP 发送数据包的功能。数据包可能丢失或无序到达，因此我们建议您在需要保证交付时使用 TCPSocket。

构造函数接受 NetworkStack 指针以打开指定 NetworkInterface 上的套接字。如果你没有传入构造函数，那么你必须调用 open 来初始化套接字。

UDPSocket 类参考

UDPSocket 类参考

公共成员函数
	UDPSocket ()
template
	UDPSocket (S *stack)
virtual	~UDPSocket ()
virtual nsapi_size_or_error_t	sendto (const char *host, uint16_t port, const void *data, nsapi_size_t size)
virtual nsapi_size_or_error_t	sendto (const SocketAddress &address, const void *data, nsapi_size_t size)
virtual nsapi_size_or_error_t	recvfrom (SocketAddress *address, void *data, nsapi_size_t size)
virtual nsapi_error_t	connect (const SocketAddress &address)
virtual nsapi_size_or_error_t	send (const void *data, nsapi_size_t size)
virtual nsapi_size_or_error_t	recv (void *data, nsapi_size_t size)
virtual Socket *	accept (nsapi_error_t *error=NULL)
virtual nsapi_error_t	listen (int backlog=1)
公共成员函数继承自 InternetSocket
virtual	~InternetSocket ()
nsapi_error_t	open (NetworkStack *stack)
template
nsapi_error_t	open (S *stack)
virtual nsapi_error_t	close ()
int	join_multicast_group (const SocketAddress &address)
int	leave_multicast_group (const SocketAddress &address)
nsapi_error_t	bind (uint16_t port)
nsapi_error_t	bind (const char *address, uint16_t port)
virtual nsapi_error_t	bind (const SocketAddress &address)
virtual void	set_blocking (bool blocking)
virtual void	set_timeout (int timeout)
virtual nsapi_error_t	setsockopt (int level, int optname, const void *optval, unsigned optlen)
virtual nsapi_error_t	getsockopt (int level, int optname, void *optval, unsigned *optlen)
virtual void	sigio (mbed::Callback< void()> func)
void	attach (mbed::Callback< void()> func)
template
void	attach (T *obj, M method)
公共成员函数继承自 Socket
virtual	~Socket ()

受保护的成员函数
virtual nsapi_protocol_t	get_proto ()
受保护的成员函数继承自 InternetSocket
virtual void	event ()
int	modify_multicast_group (const SocketAddress &address, nsapi_socket_option_t socketopt)

其他继承成员
受保护的属性继承自 InternetSocket
NetworkStack *	_stack
nsapi_socket_t	_socket
uint32_t	_timeout
mbed::Callback< void()>	_event
mbed::Callback< void()>	_callback
rtos::EventFlags	_event_flag
rtos::Mutex	_lock
SocketAddress	_remote_peer
uint8_t	_readers
uint8_t	_writers
volatile unsigned	_pending
bool	_factory_allocated
从中继承的静态保护属性 InternetSocket
static const int	READ_FLAG = 0x1u
static const int	WRITE_FLAG = 0x2u
static const int	FINISHED_FLAG = 0x3u

UDPSocket 示例

以下是通过向 NIST Internet 时间服务发送请求来读取当前 UTC 时间的 UDP 示例。

main.cpp                                                                                                                                                 导入到 Mbed IDE

#include "mbed.h"
#include "EthernetInterface.h"
 
// Network interface
EthernetInterface net;
 
// Time protocol implementation : Address: time.nist.gov UDPPort: 37  
 
typedef struct {
    uint32_t secs;         // Transmit Time-stamp seconds.
}ntp_packet;
 
int main() {
    // Bring up the ethernet interface
    printf("UDP Socket example\n");
    if(0 != net.connect()) {
        printf("Error connecting\n");
        return -1;
    }
 
    // Show the network address
    const char *ip = net.get_ip_address();
    printf("IP address is: %s\n", ip ? ip : "No IP");
        
    UDPSocket sock(&net);
    SocketAddress sockAddr;
 
    char out_buffer[] = "time";
    if(0 > sock.sendto("time.nist.gov", 37, out_buffer, sizeof(out_buffer))) {
        printf("Error sending data\n");
        return -1;
    }
    
    ntp_packet in_data;
    int n = sock.recvfrom(&sockAddr, &in_data, sizeof(ntp_packet));
    in_data.secs = ntohl( in_data.secs ) - 2208988800;    // 1900-1970
    printf("Time Received %lu seconds since 1/01/1900 00:00 GMT\n", 
                        (uint32_t)in_data.secs);
    printf("Time = %s", ctime(( const time_t* )&in_data.secs));
    
    printf("Time Server Address: %s Port: %d\n\r", 
                               sockAddr.get_ip_address(), sockAddr.get_port());
    
    // Close the socket and bring down the network interface
    sock.close();
    net.disconnect();
    return 0;
}

相关内容

• TCPSocket API 参考。