在winpcap中创建udp完整报文包含以太网帧头,包含计算校验实现,并且发送数据,使用c++编写实例
时间: 2024-10-20 15:04:41 浏览: 5
WinPCAP是一个网络抓包库,它允许你在Windows平台上直接读取和写入网络数据包。在C++中使用WinPCAP来创建UDP完整报文并添加以太网帧头,你需要先安装libpcap库,并了解基本的数据链路层(如以太网)和网络层(如IP和UDP)结构。
以下是一个简单的示例,展示如何创建一个完整的UDP报文(包括以太网和IP头部),然后加上校验和:
```cpp
#include <pcap.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
// Ethernet header structure
struct eth_hdr {
uint8_t destination[6];
uint8_t source[6];
uint16_t type; // Must be set to htons(0x800) for IP packets
};
// IPv4 header structure
struct ip_hdr {
uint8_t version_ihl;
uint16_t tos;
uint16_t tot_len; // Including headers and data
uint16_t id;
uint16_t frag_off;
uint8_t ttl;
uint8_t protocol;
uint16_t checksum; // Must be initialized before filling the packet
struct in_addr src_addr;
struct in_addr dst_addr;
};
// UDP header structure
struct udphdr {
uint16_t src_port;
uint16_t dst_port;
uint16_t len;
uint16_t check; // Must be calculated and initialized
};
void compute_udp_checksum(uint16_t* packet, size_t length) {
// ... implement a function to calculate UDP checksum
// (See https://en.wikipedia.org/wiki/User Datagram Protocol#Checksumming)
}
int main() {
char errbuf[PCAP_ERRBUF_SIZE];
pcap_t *handle = pcap_open_live("eth0", BUFSIZ, 1, -1, errbuf);
if (handle == NULL) {
printf("Error opening capture device: %s\n", errbuf);
return 1;
}
// Ethernet frame parameters
eth_hdr eth;
memset(ð, 0, sizeof(eth));
eth.type = htons(ETH_P_IP); // For IP
// IP parameters
ip_hdr ip;
ip.src_addr.s_addr = htonl(INADDR_ANY);
ip.dst_addr.s_addr = htonl(INADDR_LOOPBACK);
ip.protocol = IPPROTO_UDP;
// UDP parameters
udphdr udp;
udp.src_port = htons(12345);
udp.dst_port = htons(67890);
// Create a buffer for the full packet
char packet[ETHERNET_FRAME_LEN + IP_HEADER_LEN + UDP_HEADER_LEN];
size_t total_len = ETH_HEADER_LEN + IP_HEADER_LEN + UDP_HEADER_LEN;
// Build the packet
memcpy(packet, ð, sizeof(eth));
packet += sizeof(eth);
memcpy(packet, &ip, sizeof(ip));
packet += sizeof(ip);
memcpy(packet, &udp, sizeof(udp));
// Calculate and set the UDP checksum
compute_udp_checksum((uint16_t*)packet, UDP_HEADER_LEN);
ip.checksum = htons(inet_cksum((unsigned short*)packet, UDP_HEADER_LEN));
// Send the packet
sendpacket(handle, packet, total_len, 0);
pcap_close(handle);
return 0;
}
```
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