Winpcap数据包的抓取及还原_清空pcap_next_ex中pkt_data指向的缓存

转载：https://blog.csdn.net/x_white/article/details/8545593

winpcap技术手册，除了安装文件里doc文件下有个帮助，这里在给一个：http://www.ferrisxu.com/WinPcap/html/index.html

这里我们用pcap_next_ex 函数抓取到数据包后，我们就要开始提取其中的关键信息了，这里我保存在了pkt_data里，之后又传到了处理函数中

代码如下，我也已经写的很清楚了。其中MAC地址是在数据链路层获取的，其他的诸如端口号，IP等都是通过分析IP包和TCP包获取。

唯一需要注意的就是在定义结构体的时候要注意字节的大小，不然获取的信息就是错误的了。

#include <stdio.h>
#include <iostream>
#define HAVE_REMOTE
#include "pcap.h"
#include "remote-ext.h"
 
#pragma comment(lib, "Ws2_32.lib")
#pragma comment(lib, "wpcap.lib")
 
using namespace std;
 
FILE* fp;
 
// 以太网协议格式的定义
typedef struct ether_header {
	u_char ether_dhost[6];		// 目标地址
	u_char ether_shost[6];		// 源地址
	u_short ether_type;			// 以太网类型
}ether_header;
 
// 用户保存4字节的IP地址
typedef struct ip_address {
	u_char byte1;
	u_char byte2;
	u_char byte3;
	u_char byte4;
}ip_address;
 
 
// 用于保存IPV4的首部
typedef struct ip_header {
#ifdef WORDS_BIGENDIAN
	u_char ip_version : 4, header_length : 4;
#else
	u_char header_length : 4, ip_version : 4;
#endif
 
	u_char ver_ihl;		// 版本以及首部长度，各4位
	u_char tos;			// 服务质量
	u_short tlen;		// 总长度
	u_short identification;		// 身份识别
	u_short offset;			// 分组偏移
	u_char ttl;			// 生命周期
	u_char proto;		// 协议类型
	u_short checksum;		// 包头测验码
	ip_address saddr;	// 源IP地址
	ip_address daddr;	// 目的IP地址
	u_int op_pad;		//可选 填充字段
}ip_header;
 
// 保存TCP首部
typedef struct tcp_header {
	u_short sport;
	u_short dport;
	u_int sequence;		// 序列码
	u_int ack;					// 回复码
 
#ifdef WORDS_BIGENDIAN
	u_char offset : 4, reserved : 4;		// 偏移 预留
#else
	u_char reserved : 4, offset : 4;		// 预留 偏移
#endif
	
	u_char flags;				// 标志
	u_short windows;			// 窗口大小
	u_short checksum;			// 校验和
	u_short urgent_pointer;		// 紧急指针
}tcp_header;
 
typedef struct udp_header {
	u_int32_t sport;			// 源端口
	u_int32_t dport;			// 目标端口
	u_int8_t zero;				// 保留位
	u_int8_t proto;				// 协议标识
	u_int16_t datalen;			// UDP数据长度
}udp_header;
 
typedef struct icmp_header {
	u_int8_t type;				// ICMP类型
	u_int8_t code;				// 代码
	u_int16_t checksum;			// 校验和
	u_int16_t identification;	// 标识
	u_int16_t sequence;			// 序列号
	u_int32_t init_time;		// 发起时间戳
	u_int16_t recv_time;		// 接受时间戳
	u_int16_t send_time;		// 传输时间戳
}icmp_header;
 
typedef struct arp_header { 
    u_int16_t arp_hardware_type;
    u_int16_t arp_protocol_type;
    u_int8_t arp_hardware_length;
    u_int8_t arp_protocol_length;
    u_int16_t arp_operation_code;
    u_int8_t arp_source_ethernet_address[6];
    u_int8_t arp_source_ip_address[4];
    u_int8_t arp_destination_ethernet_address[6];
    u_int8_t arp_destination_ip_address[4];
}arp_header;
 
void tcp_protocol_packet_handle(
	u_char *argument, 
	const struct pcap_pkthdr *packet_header, 
	const u_char *packet_content 
) {
	struct tcp_header *tcp_protocol;
	u_short sport;
	u_short dport;
	int header_length;
	u_short windows;
	u_short urgent_pointer;
	u_int sequence;
	u_int acknowledgement;
	u_short checksum;
	u_char flags;
 
	printf("===========TCP Protocol===========\n");
 
	tcp_protocol = (struct tcp_header*)(packet_content + 14 + 20);
	sport = ntohs(tcp_protocol->sport);
	dport = ntohs(tcp_protocol->dport);
	header_length = tcp_protocol->offset * 4;
	sequence = ntohl(tcp_protocol->sequence);
	acknowledgement = ntohl(tcp_protocol->ack);
	windows = ntohs(tcp_protocol->windows);
	urgent_pointer = ntohs(tcp_protocol->urgent_pointer);
	flags = tcp_protocol->flags;
	checksum = ntohs(tcp_protocol->checksum);
 
	fprintf(fp, "%d0%d%d%c%d", header_length, sport, dport, flags, windows);
 
	switch(dport) {
	default:
		break;
	}
 
	if(flags & 0x08) printf("PSH");
	if(flags & 0x10) printf("ACK");
	if(flags & 0x02) printf("SYN");
	if(flags & 0x20) printf("URG");
	if(flags & 0x01) printf("FIN");
	if(flags & 0x04) printf("RST");
	printf("\n");
}
 
void udp_protocol_packet_handle(
	u_char *argument,
	const struct pcap_pkthdr *packet_header,
	const u_char *packet_content
) {
	struct udp_header* udp_protocol;
	u_short sport;
	u_short dport;
	u_short datalen;
	
	udp_protocol = (struct udp_header*)(packet_content + 14 + 20);
	sport = ntohs(udp_protocol->sport);
	dport = ntohs(udp_protocol->dport);
	datalen = ntohs(udp_protocol->datalen);
 
	fprintf(fp, "0%d%d%d",datalen, sport, dport);
}
 
void arp_protocol_packet_handle(
	u_char *argument,
	const struct pcap_pkthdr *packet_header,
	const u_char *packet_content
) {
	struct arp_header *arp_protocol;   
    u_short protocol_type;   
    u_short hardware_type;   
    u_short operation_code;   
    u_char hardware_length;   
    u_char protocol_length;   
 
	struct tm* ltime;
	char timestr[16];
	time_t local_tv_sec;
	local_tv_sec = packet_header->ts.tv_sec;
	ltime = localtime(&local_tv_sec);
	strftime(timestr, sizeof(timestr), "%H:%M:%S", ltime);
 
    printf("--------   ARP协议    --------\n");   
    arp_protocol = (struct arp_header*)(packet_content + 14);   
    hardware_type = ntohs(arp_protocol->arp_hardware_type);   
    protocol_type = ntohs(arp_protocol->arp_protocol_type);   
    operation_code = ntohs(arp_protocol->arp_operation_code);   
    hardware_length = arp_protocol->arp_hardware_length;   
    protocol_length = arp_protocol->arp_protocol_length;
	
	fprintf(fp, "%d%s", protocol_length, timestr);
 
    switch (operation_code)   
    {
        case 1:   
            printf("ARP请求协议\n");   
            break;   
        case 2:   
            printf("ARP应答协议\n");   
            break;   
        case 3:   
            printf("RARP请求协议\n");   
            break;   
        case 4:   
            printf("RARP应答协议\n");   
            break;   
        default:   
            break;   
    }   
}
 
 
 
void icmp_protocol_packet_handle(
	u_char *argument,
	const struct pcap_pkthdr *packet_header,
	const u_char *packet_content
) {
	struct icmp_header *icmp_protocol;
	u_short type;
	u_short datalen;
	u_int init_time;
	u_int recv_time;
	u_int send_time;
 
	icmp_protocol = (struct icmp_header*)(packet_content + 14 + 20);
	datalen = sizeof(icmp_protocol);
	type = icmp_protocol->type;
	init_time = icmp_protocol->init_time;
	recv_time = icmp_protocol->recv_time;
	send_time = icmp_protocol->send_time;
 
	fprintf(fp, "%d%c%d%d%d", datalen, type, init_time, recv_time, send_time);
 
//	printf("===========ICMP Protocol==========\n");
 
	switch(icmp_protocol->type) {
	case 8:
		// 回显请求报文
		break;
	case 0:
		// 回显应答报文
		break;
	default:
		break;
	}
}
 
void ip_protocol_packet_handle(
	u_char *argument, 
	const struct pcap_pkthdr *packet_header, 
	const u_char *packet_content 
) {
	struct ip_header *ip_protocol;
	u_int header_length;
	u_char tos;
	u_short checksum;
	
	ip_address saddr;
	ip_address daddr;
	u_char ttl;
	u_short tlen;
	u_short identification;
	u_short offset;
 
	printf("===========IP Protocol===========\n");
 
	ip_protocol = (struct ip_header*)(packet_content + 14);
	header_length = ip_protocol->header_length * 4;
	checksum = ntohs(ip_protocol->checksum);
	tos = ip_protocol->tos;
	offset = ntohs(ip_protocol->offset);
 
	saddr = ip_protocol->saddr;
	daddr = ip_protocol->daddr;
	ttl = ip_protocol->ttl;
	identification = ip_protocol->identification;
	tlen = ip_protocol->tlen;
	offset = ip_protocol->offset;
 
	fprintf(fp, "%d%d%c%d%d%d", saddr, daddr, ttl, identification, tlen, offset);
 
	switch(ip_protocol->proto) {
	case 6:
		tcp_protocol_packet_handle(argument, packet_header, packet_content);
		break;
	case 17:
		udp_protocol_packet_handle(argument, packet_header, packet_content);
		break;
	case 1:
		icmp_protocol_packet_handle(argument, packet_header, packet_content);
		break;
	default:
		break;
	}
}
 
 
void ethernet_protocol_packet_handle (
	u_char *argument, 
	const struct pcap_pkthdr *packet_header, 
	const u_char *packet_content
) {
	u_short ethernet_type;		// 以太网类型
	struct ether_header *ethernet_protocol;		// 以太网协议变量
	u_char *mac_string;			// 以太网地址
 
	ethernet_protocol = (struct ether_header*)packet_content;		// 获取以太网数据内容
	printf("Ethernet type is : \n");
	ethernet_type = ntohs(ethernet_protocol->ether_type);	// 获取以太网类型
	printf("	%04x\n", ethernet_type);
 
	
 
	switch(ethernet_type) {
	case 0x0800:
		printf("The network layer is IP protocol\n");
		break;
	case 0x0806:
		printf("The network layer is ARP protocol\n");
		break;
	default:
		break;
	}
 
	// 获取以太网源地址
//	printf("MAC Source Address is : \n");
	mac_string = ethernet_protocol->ether_shost;
	
	fprintf(fp, "%02x:%02x:%02x:%02x:%02x:%02x", 
		*mac_string,
		*(mac_string + 1),
		*(mac_string + 2),
		*(mac_string + 3),
		*(mac_string + 4),
		*(mac_string + 5)
		);
 
	// 获取以太网目的地址
//	printf("MAC Target Address is : \n");
	mac_string = ethernet_protocol->ether_dhost;
	fprintf(fp, "%02x:%02x:%02x:%02x:%02x:%02x", 
		*mac_string,
		*(mac_string + 1),
		*(mac_string + 2),
		*(mac_string + 3),
		*(mac_string + 4),
		*(mac_string + 5)
		);
 
	fprintf(fp, "%d", sizeof(packet_content));
 
	switch(ethernet_type) {
	case 0x0800:
		ip_protocol_packet_handle(argument, packet_header, packet_content);
		break;
	default:
		break;
	}
}
 
int main() {
	pcap_if_t *alldevs;
	pcap_if_t *d;
	pcap_t *adhandle;
	char errbuf[PCAP_ERRBUF_SIZE];
	int inum;
	int i = 0;
	u_int netmask;
	char packet_filter[] = "ip and tcp";
	struct bpf_program fcode;
	int res;
	struct pcap_pkthdr *header;
	struct tm *ltime;
	const u_char *pkt_data;
	time_t local_tv_sec;
	char timestr[16];
	ip_header *ih;
 
	// 获得设备列表 pcap_findalldevs_ex()
 
	if(pcap_findalldevs_ex(PCAP_SRC_IF_STRING, NULL, &alldevs, errbuf) == -1) {
		fprintf(stderr, "Error in pcap_findalldevs: %s\n", errbuf);
		exit(1);
	}
 
	for(d = alldevs; d; d = d->next) {
		printf("%d. %s", ++i, d->name);
		if(d->description) {
			printf("(%s)\n", d->description);
		}
		else {
			printf("No description available\n");
		}
	}
	
	if(0 == i) {
		printf("\nNo interface found!Make sure WinPcap is installed\n");
		return -1;
	}
 
	printf("Enter the interface number(1-%d):", i);
	scanf_s("%d", &inum);
	if(inum < 1 || inum > i) {
		printf("\nInterface number out of range.\n");
		pcap_freealldevs(alldevs);
		return -1;
	}
 
	for(d = alldevs, i = 0; i < inum-1; d=d->next, i++);
	// 跳转到该设备，打开适配器
 
	// 设备名，要捕捉的数据包的部分（65536保证能捕获到不同数据链路层上的每个数据包的全部内容），混杂模式，读取超时时间，错误缓冲池
	if((adhandle = pcap_open_live(d->name, 65536, 1, 1000, errbuf)) == NULL) {
		fprintf(stderr, "\nUnable to open the adapter.%s is not supported by WinPcap\n", errbuf);
		pcap_freealldevs(alldevs);
		return -1;
	}
	// 检查数据链路层（只考虑了以太网）
	if(pcap_datalink(adhandle) != DLT_EN10MB) {
		fprintf(stderr, "\nThis program works only on Ethernet networks.\n");
		pcap_freealldevs(alldevs);
		return -1;
	}
 
	if(d->addresses != NULL) {
		// 获得接口的第一个地址的掩码
		netmask = ((struct sockaddr_in*)(d->addresses->netmask))->sin_addr.S_un.S_addr;
	}
	else {
		netmask = 0xffffff;
	}
/*
	// 编译过滤器
	if(pcap_compile(adhandle, &fcode, packet_filter, 1, netmask) < 0) {
		fprintf(stderr, "\nUnable to compile the packet filter.Check the syntax\n");
		pcap_freealldevs(alldevs);
		return -1;
	}
	
	// 设置过滤器
	
	if(pcap_setfilter(adhandle, &fcode) < 0) {
		fprintf(stderr, "\nError setting the filter.\n");
		pcap_freealldevs(alldevs);
		return -1;
	}
	printf("\nlistenting on %s...\n", d->description);
*/
	fp = freopen("in.txt", "w", stdin);
 
	while((res = pcap_next_ex(adhandle, &header, &pkt_data)) >= 0) {	
 
		// 请求超时
		if(0 == res) {
			continue;
		}
 
		// 分析数据包
		ethernet_protocol_packet_handle(NULL, header, pkt_data);
 
		// 将时间戳转换成可识别的格式
		local_tv_sec = header->ts.tv_sec;
		ltime = localtime(&local_tv_sec);
		strftime(timestr, sizeof(timestr), "%H:%M:%S", ltime);
		ih = (ip_header *)(pkt_data + 14); //以太网头部长度
 
		// 输出时间和IP信息
		printf("%s.%.6d len:%d ", timestr, header->ts.tv_usec, header->len);
 
		printf("%d.%d.%d.%d -> %d.%d.%d.%d\n",
	        ih->saddr.byte1,
	        ih->saddr.byte2,
	        ih->saddr.byte3,
	        ih->saddr.byte4,
	        ih->daddr.byte1,
	        ih->daddr.byte2,
	        ih->daddr.byte3,
			ih->daddr.byte4);
	}
 
	
	if(-1 == res) {
		printf("Error reading the packet:%s\n", pcap_geterr(adhandle));
		return -1;
	}
	pcap_freealldevs(alldevs);
 
	fclose(fp);
	fclose(stdin);
 
	return 0;
}