@xunuo
2017-08-05T15:02:32.000000Z
字数 15539
阅读 1302
网络数据包分析
用一个两个链表:tcpsessionhead和tcpnodehead;
第一个链表用来确定唯一的一次tcp会话,则需要六元组(源mac,目的mac,源ip,目的ip,源端口,目的端口)(其实实际上可以不用源mac和目的mac),以及一个指向下一个节点的指针next和指向对应会话具体内容的指针tcpnodehead;
第二个链表存该会话的具体内容L:syn,seq,fin,len,以及该数据包传输的数据data[];
只是单纯的把该数据包内的东西解析出来了而已;
当检测到的数据包的syn==1&&是第一次出现syn=1时,就新建一个链表来存该tcp会话,如果检测到数据包的syn==0&&fin==0&&数据包除以太网头,ip头,tcp头外,数据长度不为0,则说明有数据传输,则将这个数据包加入tcpnode链表;如果fin==1,则说明数据传输结束,可以打印出数据。
首先创建tcpsession链表函数create():
将该数据包的六元祖存好,然后记住:一定要将next和tcpnodehead置空。不然会出问题,后面如果要用到他们的时候会无法读取内存。
插入函数insert():
在插入之前要先查一遍它所在的tcp会话(其实文件里只有一个,貌似没必要。。);然后分一下几种情况:如果这个数据包是第一个插入的,那么直接进去就行了,如果不是,就要看它的seq的大小和tcpnode链表里面已经存在的节点的seq比较,然后插入合适的位置。
#include "pcap.h"
const int MAXETHERLEN = 1500;
struct ether_header
{
u_int8_t ether_dhost[6];//目的mac;
u_int8_t ether_shost[6];//源mac;
u_int16_t ether_type;
};
/*ip地址*/
typedef struct ip_address
{
u_char byte1;
u_char byte2;
u_char byte3;
u_char byte4;
} ip_address;
/*IPv4协议头*/
struct ip_header
{
#if defined(WORDS_BIENDIAN)
u_int8_t ip_version : 4, ip_header_length : 4;
#else
u_int8_t ip_header_length : 4, ip_version : 4;
#endif
u_int8_t ip_tos;
u_int16_t ip_length;
u_int16_t ip_id;
u_int16_t ip_off;
u_int8_t ip_ttl;
u_int8_t ip_protocol;
u_int16_t ip_checksum;
ip_address saddr; /*源地址(Source address)*/
ip_address daddr; /*目的地址(Destination address)*/
};
//TCP协议头
#define __LITTLE_ENDIAN_BITFIELD
struct tcphdr
{
u_int16_t source_port; /*源地址端口*/
u_int16_t dest_port; /*目的地址端口*/
u_int32_t seq; /*序列号*/
u_int32_t ack_seq; /*确认序列号*/
u_int8_t res1 : 3, /*偏移*/
doff : 1, /*保留*/
tcp_header_length : 4;
u_int8_t fin : 1, /*关闭连接标志*/
syn : 1, /*请求连接标志*/
rst : 1, /*重置连接标志*/
psh : 1, /*接收方尽快将数据放到应用层标志*/
ack : 1, /*确认序号标志*/
urg : 1, /*紧急指针标志*/
ece : 1, /*拥塞标志位*/
cwr : 1; /*拥塞标志位*/
u_int16_t flag;
u_int16_t window; /*滑动窗口大小*/
u_int16_t check; /*校验和*/
u_int16_t urg_ptr; /*紧急字段指针*/
};
/*两个链表*/
/*list.1==tcplist*/
typedef struct tcpnode
{
int syn;
int fin;
unsigned long seq;
int len;
tcpnode *prev;
tcpnode *next;
unsigned char data[MAXETHERLEN];
}node;
/*list.2=tcpsession*/
typedef struct tcpsession
{
ip_address saddr;
ip_address daddr;
unsigned short sport;
unsigned short dport;
tcpsession* next;
tcpnode *tcplisthead;
}tcpss;
void createtcpsession(tcpss *tcpsessionhead);
bool isempty(tcpss* tcpsessionhead);
bool search(tcpss *head);
int insert(tcpss* tcpsessionheadconst, u_int32_t &cnt, int &flag1);
void print(FILE* file, tcpss* tcpsessionhead);
struct pcap_pkthdr *header;
const u_char *packet_content;
struct ether_header *ethernet_protocol;
struct ip_header *ip_protocol;
struct tcphdr *tcp_protocol;
int flag = 0;
u_int32_t fin_seq = 0;
u_int32_t syn_seq = 0;
u_int32_t cnt = 0;
int flag1;
int len;
int main(int argc, char* argv[])
{
if (argc <= 1)
{
printf("argc<=1,break!\n");
return -1;
}
pcap_t *adapterHandle;//适配器句柄;
char errorBuffer[PCAP_ERRBUF_SIZE];//错误缓冲区;
char source[PCAP_BUF_SIZE];
if (pcap_createsrcstr(source, PCAP_SRC_FILE, NULL, NULL, argv[1], errorBuffer) != 0)
{
printf("数据源创建失败!\n");
return -1;
}
if ((adapterHandle = pcap_open(source, 65536, PCAP_OPENFLAG_PROMISCUOUS, 1000, NULL, errorBuffer)) == NULL)
{
printf("文件打开失败!\n");
return -1;
}
tcpsession* tcpsessionhead = (tcpsession*)malloc(sizeof(tcpsession));
tcpsessionhead->next = nullptr;
tcpsessionhead->tcplisthead = nullptr;
FILE* file;
if (fopen_s(&file, argv[2], "w+") != 0)
{
printf("打开文件失败!\n");
}
int pkt_number = 1;
int res;
while ((res = pcap_next_ex(adapterHandle, &header, &packet_content)) >= 0)
{
if (res == 0)/* 超时时间到 */
continue;
printf("这是第%d个数据包!\n", pkt_number++);
/*for (int i = 1; i <= header->len; i++)
{
printf("%02x ", packet_content[i - 1]);
if (i % 8 == 0)
printf(" ");
if (i % 16 == 0)
printf("\n");
}
printf("\n");*/
ethernet_protocol = (struct ether_header*)packet_content;
ip_protocol = (struct ip_header *)(packet_content + sizeof(ether_header));
tcp_protocol = (struct tcphdr *) (packet_content + sizeof(ether_header) + sizeof(ip_header));
int ip_len = ntohs(ip_protocol->ip_length);
printf("%d.%d.%d.%d\n", ip_protocol->saddr.byte1, ip_protocol->saddr.byte2, ip_protocol->saddr.byte3, ip_protocol->saddr.byte4);
printf("%d.%d.%d.%d\n", ip_protocol->daddr.byte1, ip_protocol->daddr.byte2, ip_protocol->daddr.byte3, ip_protocol->daddr.byte4);
len = ip_len - sizeof(ip_header) - tcp_protocol->tcp_header_length * 4;
printf("长度:%d %d\n", ip_len - sizeof(ip_header) - tcp_protocol->tcp_header_length * 4, sizeof(ip_header) + tcp_protocol->tcp_header_length * 4);
printf("%02x %02x\n", ntohs(tcp_protocol->source_port), ntohs(tcp_protocol->dest_port));
printf("%u %u\n", ntohl(tcp_protocol->seq), ntohl(tcp_protocol->ack_seq));
printf("syn and fin:%d %d\n", tcp_protocol->syn, tcp_protocol->fin);
if (tcp_protocol->syn == 1 && flag == 0)
{
createtcpsession(tcpsessionhead);
flag = 1;
syn_seq = ntohl(tcp_protocol->seq);
}
else if (tcp_protocol->syn == 0 && tcp_protocol->fin == 0 && len>0)
{
cnt = insert(tcpsessionhead, cnt, flag1);
}
else if (tcp_protocol->fin == 1)
{
flag = 0;
print(file, tcpsessionhead);
fclose(file);
break;
}
printf("\n");
}
if (res == -1)
{
printf("Error reading the packets: %s\n", pcap_geterr(adapterHandle));
return -1;
}
return 0;
}
void createtcpsession(tcpss *tcpsessionhead)
{
tcpss *root = tcpsessionhead;
while (!isempty(root))
{
root = root->next;
}
root->saddr.byte1 = ip_protocol->saddr.byte1;
root->saddr.byte2 = ip_protocol->saddr.byte2;
root->saddr.byte3 = ip_protocol->saddr.byte3;
root->saddr.byte4 = ip_protocol->saddr.byte4;
root->daddr.byte1 = ip_protocol->daddr.byte1;
root->daddr.byte2 = ip_protocol->daddr.byte2;
root->daddr.byte3 = ip_protocol->daddr.byte3;
root->daddr.byte4 = ip_protocol->daddr.byte4;
root->sport = tcp_protocol->source_port;
root->dport = tcp_protocol->dest_port;
root->next = (tcpss*)malloc(sizeof(tcpss));
root->next->next = NULL;
root->next->tcplisthead = NULL;
}
bool isempty(tcpss* tcpsessionhead)
{
if (tcpsessionhead->next == NULL)
return true;
else
return false;
}
bool search(tcpss *head)
{
if ((head->saddr.byte1 == ip_protocol->saddr.byte1&&head->saddr.byte2 == ip_protocol->saddr.byte2&&head->saddr.byte3 == ip_protocol->saddr.byte3&&head->saddr.byte4 == ip_protocol->saddr.byte4
&&head->daddr.byte1 == ip_protocol->daddr.byte1&&head->daddr.byte2 == ip_protocol->daddr.byte2&&head->daddr.byte3 == ip_protocol->daddr.byte3&&head->daddr.byte4 == ip_protocol->daddr.byte4
&&head->sport == tcp_protocol->source_port&&head->dport == tcp_protocol->dest_port)
|| (head->saddr.byte1 == ip_protocol->daddr.byte1&&head->saddr.byte2 == ip_protocol->daddr.byte2&&head->saddr.byte3 == ip_protocol->daddr.byte3&&head->saddr.byte4 == ip_protocol->daddr.byte4
&&head->daddr.byte1 == ip_protocol->saddr.byte1&&head->daddr.byte2 == ip_protocol->saddr.byte2&&head->daddr.byte3 == ip_protocol->saddr.byte3&&head->daddr.byte4 == ip_protocol->saddr.byte4
&&head->sport == tcp_protocol->dest_port&&head->dport == tcp_protocol->source_port)
)
return true;
else
return false;
}
int insert(tcpss* tcpsessionhead, u_int32_t &cnt, int &flag1)
{
tcpss* tcpsshead = tcpsessionhead;
while (!search(tcpsshead))
{
tcpsshead = tcpsshead->next;
}
if (tcpsshead->tcplisthead == NULL)
{
cnt += len;
tcpnode* tcpnodehead = (tcpnode*)malloc(sizeof(tcpnode));
tcpsshead->tcplisthead = tcpnodehead;
tcpnodehead->prev = tcpsshead->tcplisthead;
tcpnodehead->syn = tcp_protocol->syn;
tcpnodehead->fin = tcp_protocol->fin;
tcpnodehead->seq = ntohl(tcp_protocol->seq);
tcpnodehead->len = len;
tcpnodehead->next = NULL;
for (int i = 0; i < tcpnodehead->len; i++)
tcpnodehead->data[i] = packet_content[i + sizeof(ether_header)+sizeof(ip_header) + tcp_protocol->tcp_header_length * 4];
}
else
{
tcpnode* tcpnodehead = tcpsshead->tcplisthead;
tcpnode* tcpnewnode = (tcpnode*)malloc(sizeof(tcpnode));
tcpnewnode->syn = tcp_protocol->syn;
tcpnewnode->fin = tcp_protocol->fin;
tcpnewnode->seq = ntohl(tcp_protocol->seq);
tcpnewnode->len = len;
tcpnewnode->next = NULL;
for (int i = 0; i < tcpnewnode->len; i++)
{
tcpnewnode->data[i] = packet_content[i + sizeof(ether_header) + sizeof(ip_header) + tcp_protocol->tcp_header_length * 4];
}
if (tcp_protocol->fin == 1)
flag1 = 1;
if (tcpnodehead->seq > tcpnewnode->seq)
{
cnt += len;
tcpsshead->tcplisthead = tcpnewnode;
tcpnewnode->prev = tcpsshead->tcplisthead;
tcpnewnode->next = tcpnodehead;
tcpnodehead->prev = tcpnewnode;
}
else
{
cnt += len;
while (tcpnodehead->seq < tcpnewnode->seq)
{
if (&tcpnodehead->next == NULL||tcpnodehead->next->seq > tcpnewnode->seq)
{
tcpnewnode->prev = tcpnodehead;
tcpnewnode->next = tcpnodehead->next;
tcpnodehead->next = tcpnewnode;
tcpnodehead->next->prev = tcpnewnode;
break;
}
else
tcpnodehead = tcpnodehead->next;
}
}
}
return cnt;
}
void print(FILE* file, tcpss* tcpsessionhead)
{
tcpss* tcpsshead = tcpsessionhead;
while (!search(tcpsshead))
{
tcpsshead = tcpsshead->next;
}
tcpnode* tcpnodehead=tcpsshead->tcplisthead;
while (tcpnodehead->next != NULL)
{
for (int i = 1; i < tcpnodehead->len; i++)
{
printf("%c", tcpnodehead->data[i - 1]);
fprintf(file, "%c", tcpnodehead->data[i - 1]);
}
//if (tcpnodehead->next == NULL)
//break;
//else
tcpnodehead = tcpnodehead->next;
}
}
#include "pcap.h"
const int MAXETHERLEN = 1500;
struct ether_header
{
u_int8_t ether_dhost[6];//目的mac;
u_int8_t ether_shost[6];//源mac;
u_int16_t ether_type;
};
/*ip地址*/
typedef struct ip_address
{
u_char byte1;
u_char byte2;
u_char byte3;
u_char byte4;
} ip_address;
/*IPv4协议头*/
struct ip_header
{
#if defined(WORDS_BIENDIAN)
u_int8_t ip_version : 4, ip_header_length : 4;
#else
u_int8_t ip_header_length : 4, ip_version : 4;
#endif
u_int8_t ip_tos;
u_int16_t ip_length;
u_int16_t ip_id;
u_int16_t ip_off;
u_int8_t ip_ttl;
u_int8_t ip_protocol;
u_int16_t ip_checksum;
ip_address saddr; /*源地址(Source address)*/
ip_address daddr; /*目的地址(Destination address)*/
};
//TCP协议头
#define __LITTLE_ENDIAN_BITFIELD
struct tcphdr
{
u_int16_t source_port; /*源地址端口*/
u_int16_t dest_port; /*目的地址端口*/
u_int32_t seq; /*序列号*/
u_int32_t ack_seq; /*确认序列号*/
u_int8_t res1 : 3, /*偏移*/
doff : 1, /*保留*/
tcp_header_length : 4;
u_int8_t fin : 1, /*关闭连接标志*/
syn : 1, /*请求连接标志*/
rst : 1, /*重置连接标志*/
psh : 1, /*接收方尽快将数据放到应用层标志*/
ack : 1, /*确认序号标志*/
urg : 1, /*紧急指针标志*/
ece : 1, /*拥塞标志位*/
cwr : 1; /*拥塞标志位*/
u_int16_t flag;
u_int16_t window; /*滑动窗口大小*/
u_int16_t check; /*校验和*/
u_int16_t urg_ptr; /*紧急字段指针*/
};
/*两个链表*/
/*list.1==tcplist*/
typedef struct tcpnode
{
int syn;
int fin;
unsigned long seq;
int len;
tcpnode *prev;
tcpnode *next;
unsigned char data[MAXETHERLEN];
}node;
/*list.2=tcpsession*/
typedef struct tcpsession
{
ip_address saddr;
ip_address daddr;
unsigned short sport;
unsigned short dport;
tcpsession* next;
tcpnode *tcplisthead;
}tcpss;
tcpsession* createtcpsession(tcpss *tcpsessionhead);
bool isempty(tcpss* tcpsessionhead);
bool search(tcpss *head);
int insert(tcpss* tcpsessionheadconst, u_int32_t &cnt, int &flag1);
void print(FILE* file, tcpss* tcpsessionhead);
struct pcap_pkthdr *header;
const u_char *packet_content;
struct ether_header *ethernet_protocol;
struct ip_header *ip_protocol;
struct tcphdr *tcp_protocol;
tcpsession* tcpsessionhead = (tcpsession*)malloc(sizeof(tcpsession));
tcpsession* tcpsshead = tcpsessionhead;
int flag = 0;
u_int32_t fin_seq = 0;
u_int32_t syn_seq = 0;
u_int32_t cnt = 0;
int flag1;
int len;
int main(int argc, char* argv[])
{
if (argc <= 1)
{
printf("argc<=1,break!\n");
return -1;
}
pcap_t *adapterHandle;//适配器句柄;
char errorBuffer[PCAP_ERRBUF_SIZE];//错误缓冲区;
char source[PCAP_BUF_SIZE];
if (pcap_createsrcstr(source, PCAP_SRC_FILE, NULL, NULL, argv[1], errorBuffer) != 0)
{
printf("数据源创建失败!\n");
return -1;
}
if ((adapterHandle = pcap_open(source, 65536, PCAP_OPENFLAG_PROMISCUOUS, 1000, NULL, errorBuffer)) == NULL)
{
printf("文件打开失败!\n");
return -1;
}
tcpsessionhead->next = NULL;;
tcpsshead->next = NULL;
tcpsessionhead->tcplisthead = NULL;
tcpsshead->tcplisthead = NULL;
FILE* file1,*file2;
if (fopen_s(&file1, argv[2], "w+") != 0)
{
printf("打开文件失败!\n");
}
if (fopen_s(&file2, argv[3], "w+") != 0)
{
printf("打开文件失败!\n");
}
int pkt_number = 1;
int res;
int flag3 = 0;
while ((res = pcap_next_ex(adapterHandle, &header, &packet_content)) >= 0)
{
if (res == 0)/* 超时时间到 */
continue;
printf("这是第%d个数据包!\n", pkt_number++);
/*for (int i = 1; i <= header->len; i++)
{
printf("%02x ", packet_content[i - 1]);
if (i % 8 == 0)
printf(" ");
if (i % 16 == 0)
printf("\n");
}
printf("\n");*/
ethernet_protocol = (struct ether_header*)packet_content;
ip_protocol = (struct ip_header *)(packet_content + sizeof(ether_header));
tcp_protocol = (struct tcphdr *) (packet_content + sizeof(ether_header) + sizeof(ip_header));
int ip_len = ntohs(ip_protocol->ip_length);
printf("%d.%d.%d.%d\n", ip_protocol->saddr.byte1, ip_protocol->saddr.byte2, ip_protocol->saddr.byte3, ip_protocol->saddr.byte4);
printf("%d.%d.%d.%d\n", ip_protocol->daddr.byte1, ip_protocol->daddr.byte2, ip_protocol->daddr.byte3, ip_protocol->daddr.byte4);
len = ip_len - sizeof(ip_header) - tcp_protocol->tcp_header_length * 4;
printf("长度:%d %d\n", ip_len - sizeof(ip_header) - tcp_protocol->tcp_header_length * 4, sizeof(ip_header) + tcp_protocol->tcp_header_length * 4);
printf("%02x %02x\n", ntohs(tcp_protocol->source_port), ntohs(tcp_protocol->dest_port));
printf("%u %u\n", ntohl(tcp_protocol->seq), ntohl(tcp_protocol->ack_seq));
printf("syn and fin:%d %d\n", tcp_protocol->syn, tcp_protocol->fin);
if (tcp_protocol->syn == 1)
{
tcpsshead=createtcpsession(tcpsshead);
}
else if (tcp_protocol->syn == 0 && tcp_protocol->fin == 0 && len>0)
{
cnt = insert(tcpsessionhead, cnt, flag1);
}
else if (tcp_protocol->fin == 1)
{
if (flag3 == 0)
{
print(file1,tcpsessionhead);
///fclose(file1);
flag3 = 1;
}
else
{
print(file2, tcpsessionhead);
//fclose(file2);
}
}
printf("\n");
}
if (res == -1)
{
printf("Error reading the packets: %s\n", pcap_geterr(adapterHandle));
return -1;
}
return 0;
}
tcpsession* createtcpsession(tcpss *tcpsessionhead)
{
tcpss *root = tcpsessionhead;
while (!isempty(root))
{
root = root->next;
}
root->saddr.byte1 = ip_protocol->saddr.byte1;
root->saddr.byte2 = ip_protocol->saddr.byte2;
root->saddr.byte3 = ip_protocol->saddr.byte3;
root->saddr.byte4 = ip_protocol->saddr.byte4;
root->daddr.byte1 = ip_protocol->daddr.byte1;
root->daddr.byte2 = ip_protocol->daddr.byte2;
root->daddr.byte3 = ip_protocol->daddr.byte3;
root->daddr.byte4 = ip_protocol->daddr.byte4;
root->sport = tcp_protocol->source_port;
root->dport = tcp_protocol->dest_port;
root->next = (tcpss*)malloc(sizeof(tcpss));
root->next->next = NULL;
root->next->tcplisthead = NULL;
return root;
}
bool isempty(tcpss* tcpsessionhead)
{
if (tcpsessionhead->next == NULL)
return true;
else
return false;
}
bool search(tcpss *head)
{
if ((head->saddr.byte1 == ip_protocol->saddr.byte1&&head->saddr.byte2 == ip_protocol->saddr.byte2&&head->saddr.byte3 == ip_protocol->saddr.byte3&&head->saddr.byte4 == ip_protocol->saddr.byte4
&&head->daddr.byte1 == ip_protocol->daddr.byte1&&head->daddr.byte2 == ip_protocol->daddr.byte2&&head->daddr.byte3 == ip_protocol->daddr.byte3&&head->daddr.byte4 == ip_protocol->daddr.byte4
&&head->sport == tcp_protocol->source_port&&head->dport == tcp_protocol->dest_port))
return true;
else
return false;
}
int insert(tcpss* tcpsessionhead, u_int32_t &cnt, int &flag1)
{
tcpss* tcpsshead = tcpsessionhead;
while (!search(tcpsshead))
{
tcpsshead = tcpsshead->next;
}
if (tcpsshead->tcplisthead == NULL)
{
cnt += len;
tcpnode* tcpnodehead = (tcpnode*)malloc(sizeof(tcpnode));
tcpsshead->tcplisthead = tcpnodehead;
tcpnodehead->prev = tcpsshead->tcplisthead;
tcpnodehead->syn = tcp_protocol->syn;
tcpnodehead->fin = tcp_protocol->fin;
tcpnodehead->seq = ntohl(tcp_protocol->seq);
tcpnodehead->len = len;
tcpnodehead->next = NULL;
for (int i = 0; i < tcpnodehead->len; i++)
tcpnodehead->data[i] = packet_content[i + sizeof(ether_header)+sizeof(ip_header) + tcp_protocol->tcp_header_length * 4];
}
else
{
tcpnode* tcpnodehead = tcpsshead->tcplisthead;
tcpnode* tcpnewnode = (tcpnode*)malloc(sizeof(tcpnode));
tcpnewnode->syn = tcp_protocol->syn;
tcpnewnode->fin = tcp_protocol->fin;
tcpnewnode->seq = ntohl(tcp_protocol->seq);
tcpnewnode->len = len;
tcpnewnode->next = NULL;
for (int i = 0; i < tcpnewnode->len; i++)
{
tcpnewnode->data[i] = packet_content[i + sizeof(ether_header) + sizeof(ip_header) + tcp_protocol->tcp_header_length * 4];
}
if (tcp_protocol->fin == 1)
flag1 = 1;
if (tcpnodehead->seq > tcpnewnode->seq)
{
cnt += len;
tcpsshead->tcplisthead = tcpnewnode;
tcpnewnode->prev = tcpsshead->tcplisthead;
tcpnewnode->next = tcpnodehead;
tcpnodehead->prev = tcpnewnode;
}
else if(tcpnodehead->seq < tcpnewnode->seq)
{
cnt += len;
while (tcpnodehead->seq < tcpnewnode->seq)
{
if (tcpnodehead->next == NULL||tcpnodehead->next->seq > tcpnewnode->seq)
{
tcpnewnode->prev = tcpnodehead;
tcpnewnode->next = tcpnodehead->next;
tcpnodehead->next = tcpnewnode;
tcpnodehead->next->prev = tcpnewnode;
break;
}
else
tcpnodehead = tcpnodehead->next;
}
}
}
return cnt;
}
void print(FILE* file, tcpss* tcpsessionhead)
{
tcpss* tcpsshead = tcpsessionhead;
while (!search(tcpsshead))
{
tcpsshead = tcpsshead->next;
}
tcpnode* tcpnodehead=tcpsshead->tcplisthead;
while (tcpnodehead->next != NULL)
{
for (int i = 1; i < tcpnodehead->len; i++)
{
printf("%c", tcpnodehead->data[i - 1]);
fprintf(file, "%c", tcpnodehead->data[i - 1]);
}
//if (tcpnodehead->next == NULL)
//break;
//else
tcpnodehead = tcpnodehead->next;
}
}