客服端骨架：

#include <iostream>
#include <WinSock2.h>
#pragma  comment(lib,"ws2_32.lib")

int main()
{
	WORD wVersionRequested = MAKEWORD(2, 2);
	WSADATA lpWSAData;
	WSAStartup(wVersionRequested, &lpWSAData);

	SOCKADDR_IN saddr{ 0 };
	saddr.sin_family = AF_INET;
	saddr.sin_port = htons(55555);
	saddr.sin_addr.S_un.S_addr = inet_addr("127.0.0.1");

	SOCKET sRet = socket(AF_INET, SOCK_DGRAM, 0);

	char opt= 0;
	setsockopt(sRet, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));

	char buffer[0x1000]{ 0 };
	while (true)
	{
		scanf_s("%s", buffer, sizeof(buffer));
		sendto(sRet, buffer, sizeof(buffer), 0, (PSOCKADDR)&saddr, sizeof(saddr));
	}
	closesocket(sRet);
	WSACleanup();
	system("pause");
	return 0;
}

服务端骨架：

#include <iostream>
#include <WinSock2.h>
#pragma  comment(lib,"ws2_32.lib")

//IP协议头 20字节
typedef struct _IP_HEADER
{
	//版本信息（前四位）/头长度（后四位）
	 struct cVersionAndHeaderLen
	{
		UCHAR Version : 4;
		UCHAR HeaderLen : 4;
	}cVersionAndHeaderLen;
	//服务类型
	char cTypeOfService;
	//数据包长度
	short sTotalLenOfPacket;
	//数据报ID
	short sPacketID;
	//分片信息
	short sSliceinfp;
	//存活时间
	char cTTL;
	//协议类型
	char cTypeOfProtolol;
	//校验和
	short sCheckSum;
	//源IP
	unsigned int uiSourIP;
	//目的IP
	unsigned int uiDestIP;
}IP_HEADER, *PIP_HEADER;

//UDP协议头 8字节
typedef struct _UDP_HEADER
{
	//源端口号
	unsigned short usSourPort;
	//目的端口号
	unsigned short usDestPort;
	//数据包长度
	unsigned short usLength;
	//校验和
	unsigned short usCheckSum;
}UDP_HEADER, *PUDP_HEADER;

int main()
{
	WORD wVersionRequested = MAKEWORD(2,2);
	WSADATA lpWSAData;
	WSAStartup(wVersionRequested, &lpWSAData);

	SOCKADDR_IN saddr{ 0 };
	saddr.sin_family = AF_INET;
	saddr.sin_port = htons(55555);
	saddr.sin_addr.S_un.S_addr = htonl(INADDR_ANY);

	SOCKET sRet = socket(AF_INET, SOCK_RAW, IPPROTO_UDP);

	char opt = 0;
	setsockopt(sRet, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));

	bind(sRet, (PSOCKADDR)&saddr, sizeof(saddr));

	char buffer[0x5000]{ 0 };
	sockaddr from{ 0 };
	int len = sizeof(from);
	IP_HEADER ih{ 0 };
	UDP_HEADER uh{ 0 };
	char cTemp = 0;
	while (true)
	{
		recvfrom(sRet, buffer, sizeof(buffer), 0, &from, &len);
		memcpy(&ih, buffer, 1);
		if (ih.cVersionAndHeaderLen.HeaderLen < 5)//有可能小于标准20字节
		{
			cTemp = 5 - ih.cVersionAndHeaderLen.HeaderLen + ih.cVersionAndHeaderLen.HeaderLen;
		}
		memcpy(&ih, buffer, (cTemp * 4));
		memcpy(&uh, buffer + (cTemp * 4), 8);
		in_addr  ias, iad;
		ias.S_un.S_addr = ih.uiSourIP;
		iad.S_un.S_addr = ih.uiDestIP;
		printf("源IP：%s\t端口：%d\n", inet_ntoa(ias), ntohs(uh.usSourPort));
		printf("目IP：%s\t端口：%d\n", inet_ntoa(iad), ntohs(uh.usDestPort));
		printf("数据：%s\n\n", buffer + (cTemp * 4) + 8);
		
	}
	closesocket(sRet);
	WSACleanup();
    system("pause");
    return 0;
}