win32

可以从Windows Sockets 2开始, 

虽然微软提供了官方工具， Microsoft Network Monitor 3.4， 不过我们如果能够通过相关的代码和api的调用来深入研究的话，那就大大提升了我们的学习水平。

主要用到socket, bind 和 recvfrom函数。

代码样本：

#include "stdio.h"
#include "winsock2.h"

#pragma comment(lib,"ws2_32.lib") //For winsock
#pragma warning(disable:4996)

#define SIO_RCVALL _WSAIOW(IOC_VENDOR,1) //this removes the need of mstcpip.h

void StartSniffing(SOCKET Sock); //This will sniff here and there

void ProcessPacket(char*, int); //This will decide how to digest
void PrintIpHeader(char*);
void PrintUdpPacket(char*, int);
void PrintTcpPacket(char*, int);
void PrintData(char*, int);

typedef struct ip_hdr
{
    unsigned char ip_header_len : 4; // 4-bit header length (in 32-bit words) normally=5 (Means 20 Bytes may be 24 also)
    unsigned char ip_version : 4; // 4-bit IPv4 version
    unsigned char ip_tos; // IP type of service
    unsigned short ip_total_length; // Total length
    unsigned short ip_id; // Unique identifier

    unsigned char ip_frag_offset : 5; // Fragment offset field

    unsigned char ip_more_fragment : 1;
    unsigned char ip_dont_fragment : 1;
    unsigned char ip_reserved_zero : 1;

    unsigned char ip_frag_offset1; //fragment offset

    unsigned char ip_ttl; // Time to live
    unsigned char ip_protocol; // Protocol(TCP,UDP etc)
    unsigned short ip_checksum; // IP checksum
    unsigned int ip_srcaddr; // Source address
    unsigned int ip_destaddr; // Source address
} IPV4_HDR;

typedef struct udp_hdr
{
    unsigned short source_port; // Source port no.
    unsigned short dest_port; // Dest. port no.
    unsigned short udp_length; // Udp packet length
    unsigned short udp_checksum; // Udp checksum (optional)
} UDP_HDR;

// TCP header
typedef struct tcp_header
{
    unsigned short source_port; // source port
    unsigned short dest_port; // destination port
    unsigned int sequence; // sequence number - 32 bits
    unsigned int acknowledge; // acknowledgement number - 32 bits

    unsigned char ns : 1; //Nonce Sum Flag Added in RFC 3540.
    unsigned char reserved_part1 : 3; //according to rfc
    unsigned char data_offset : 4; /*The number of 32-bit words in the TCP header.
    This indicates where the data begins.
    The length of the TCP header is always a multiple
    of 32 bits.*/

    unsigned char fin : 1; //Finish Flag
    unsigned char syn : 1; //Synchronise Flag
    unsigned char rst : 1; //Reset Flag
    unsigned char psh : 1; //Push Flag
    unsigned char ack : 1; //Acknowledgement Flag
    unsigned char urg : 1; //Urgent Flag

    unsigned char ecn : 1; //ECN-Echo Flag
    unsigned char cwr : 1; //Congestion Window Reduced Flag

    ////////////////////////////////

    unsigned short window; // window
    unsigned short checksum; // checksum
    unsigned short urgent_pointer; // urgent pointer
} TCP_HDR;


FILE* logfile;
int tcp = 0, udp = 0, icmp = 0, others = 0, igmp = 0, total = 0, i, j;
struct sockaddr_in source, dest;
char hex[2];

//Its free!
IPV4_HDR* iphdr;
TCP_HDR* tcpheader;
UDP_HDR* udpheader;

int main()
{
    SOCKET sniffer;
    struct in_addr addr;
    int in;

    char hostname[100];
    struct hostent* local;
    WSADATA wsa;

    logfile = fopen("log.txt", "w");
    if (logfile == NULL)
    {
        printf("Unable to create file.");
    }

    //Initialise Winsock
    printf("
Initialising Winsock...");
    if (WSAStartup(MAKEWORD(2, 2), &wsa) != 0)
    {
        printf("WSAStartup() failed.
");
        return 1;
    }
    printf("Initialised");

    //Create a RAW Socket
    printf("
Creating RAW Socket...");
    sniffer = socket(AF_INET, SOCK_RAW, IPPROTO_IP);
    if (sniffer == INVALID_SOCKET)
    {
        printf("Failed to create raw socket.
");
        return 1;
    }
    printf("Created.");

    //Retrive the local hostname
    if (gethostname(hostname, sizeof(hostname)) == SOCKET_ERROR)
    {
        printf("Error : %d", WSAGetLastError());
        return 1;
    }
    printf("
Host name : %s 
", hostname);

    //Retrive the available IPs of the local host
    local = gethostbyname(hostname);
    printf("
Available Network Interfaces : 
");
    if (local == NULL)
    {
        printf("Error : %d.
", WSAGetLastError());
        return 1;
    }

    for (i = 0; local->h_addr_list[i] != 0; ++i)
    {
        memcpy(&addr, local->h_addr_list[i], sizeof(struct in_addr));
        printf("Interface Number : %d Address : %s
", i, inet_ntoa(addr));
    }

    printf("Enter the interface number you would like to sniff : ");
    scanf("%d", &in);

    memset(&dest, 0, sizeof(dest));
    memcpy(&dest.sin_addr.s_addr, local->h_addr_list[in], sizeof(dest.sin_addr.s_addr));
    dest.sin_family = AF_INET;
    dest.sin_port = 0;

    printf("
Binding socket to local system and port 0 ...");
    if (bind(sniffer, (struct sockaddr*) & dest, sizeof(dest)) == SOCKET_ERROR)
    {
        printf("bind(%s) failed.
", inet_ntoa(addr));
        return 1;
    }
    printf("Binding successful");

    //Enable this socket with the power to sniff : SIO_RCVALL is the key Receive ALL ;)

    j = 1;
    printf("
Setting socket to sniff...");
    if (WSAIoctl(sniffer, SIO_RCVALL, &j, sizeof(j), 0, 0, (LPDWORD)&in, 0, 0) == SOCKET_ERROR)
    {
        printf("WSAIoctl() failed.
");
        return 1;
    }
    printf("Socket set.");

    //Begin
    printf("
Started Sniffing
");
    printf("Packet Capture Statistics...
");
    StartSniffing(sniffer); //Happy Sniffing

    //End
    closesocket(sniffer);
    WSACleanup();

    return 0;
}

void StartSniffing(SOCKET sniffer)
{
    char* Buffer = (char*)malloc(65536); //Its Big!
    int mangobyte;

    if (Buffer == NULL)
    {
        printf("malloc() failed.
");
        return;
    }

    do
    {
        mangobyte = recvfrom(sniffer, Buffer, 65536, 0, 0, 0); //Eat as much as u can

        if (mangobyte > 0)
        {
            ProcessPacket(Buffer, mangobyte);
        }
        else
        {
            printf("recvfrom() failed.
");
        }
    } while (mangobyte > 0);

    free(Buffer);
}

void ProcessPacket(char* Buffer, int Size)
{
    iphdr = (IPV4_HDR*)Buffer;
    ++total;

    switch (iphdr->ip_protocol) //Check the Protocol and do accordingly...
    {

    case 6: //TCP Protocol
        ++tcp;
        PrintTcpPacket(Buffer, Size);
        break;

    case 17: //UDP Protocol
        ++udp;
        PrintUdpPacket(Buffer, Size);
        break;

    default: //Some Other Protocol like ARP etc.
        ++others;
        break;
    }
    printf("TCP : %d UDP : %d ICMP : %d IGMP : %d Others : %d Total : %d
", tcp, udp, icmp, igmp, others, total);
}

void PrintIpHeader(char* Buffer)
{
    unsigned short iphdrlen;

    iphdr = (IPV4_HDR*)Buffer;
    iphdrlen = iphdr->ip_header_len * 4;

    memset(&source, 0, sizeof(source));
    source.sin_addr.s_addr = iphdr->ip_srcaddr;

    memset(&dest, 0, sizeof(dest));
    dest.sin_addr.s_addr = iphdr->ip_destaddr;

    fprintf(logfile, "
");
    fprintf(logfile, "IP Header
");
    fprintf(logfile, " |-IP Version : %d
", (unsigned int)iphdr->ip_version);
    fprintf(logfile, " |-IP Header Length : %d DWORDS or %d Bytes
", (unsigned int)iphdr->ip_header_len, ((unsigned int)(iphdr->ip_header_len)) * 4);
    fprintf(logfile, " |-Type Of Service : %d
", (unsigned int)iphdr->ip_tos);
    fprintf(logfile, " |-IP Total Length : %d Bytes(Size of Packet)
", ntohs(iphdr->ip_total_length));
    fprintf(logfile, " |-Identification : %d
", ntohs(iphdr->ip_id));
    fprintf(logfile, " |-Reserved ZERO Field : %d
", (unsigned int)iphdr->ip_reserved_zero);
    fprintf(logfile, " |-Dont Fragment Field : %d
", (unsigned int)iphdr->ip_dont_fragment);
    fprintf(logfile, " |-More Fragment Field : %d
", (unsigned int)iphdr->ip_more_fragment);
    fprintf(logfile, " |-TTL : %d
", (unsigned int)iphdr->ip_ttl);
    fprintf(logfile, " |-Protocol : %d
", (unsigned int)iphdr->ip_protocol);
    fprintf(logfile, " |-Checksum : %d
", ntohs(iphdr->ip_checksum));
    fprintf(logfile, " |-Source IP : %s
", inet_ntoa(source.sin_addr));
    fprintf(logfile, " |-Destination IP : %s
", inet_ntoa(dest.sin_addr));
}

void PrintTcpPacket(char* Buffer, int Size)
{
    unsigned short iphdrlen;

    iphdr = (IPV4_HDR*)Buffer;
    iphdrlen = iphdr->ip_header_len * 4;

    tcpheader = (TCP_HDR*)(Buffer + iphdrlen);

    fprintf(logfile, "

***********************TCP Packet*************************
");

    PrintIpHeader(Buffer);

    fprintf(logfile, "
");
    fprintf(logfile, "TCP Header
");
    fprintf(logfile, " |-Source Port : %u
", ntohs(tcpheader->source_port));
    fprintf(logfile, " |-Destination Port : %u
", ntohs(tcpheader->dest_port));
    fprintf(logfile, " |-Sequence Number : %u
", ntohl(tcpheader->sequence));
    fprintf(logfile, " |-Acknowledge Number : %u
", ntohl(tcpheader->acknowledge));
    fprintf(logfile, " |-Header Length : %d DWORDS or %d BYTES
"
        , (unsigned int)tcpheader->data_offset, (unsigned int)tcpheader->data_offset * 4);
    fprintf(logfile, " |-CWR Flag : %d
", (unsigned int)tcpheader->cwr);
    fprintf(logfile, " |-ECN Flag : %d
", (unsigned int)tcpheader->ecn);
    fprintf(logfile, " |-Urgent Flag : %d
", (unsigned int)tcpheader->urg);
    fprintf(logfile, " |-Acknowledgement Flag : %d
", (unsigned int)tcpheader->ack);
    fprintf(logfile, " |-Push Flag : %d
", (unsigned int)tcpheader->psh);
    fprintf(logfile, " |-Reset Flag : %d
", (unsigned int)tcpheader->rst);
    fprintf(logfile, " |-Synchronise Flag : %d
", (unsigned int)tcpheader->syn);
    fprintf(logfile, " |-Finish Flag : %d
", (unsigned int)tcpheader->fin);
    fprintf(logfile, " |-Window : %d
", ntohs(tcpheader->window));
    fprintf(logfile, " |-Checksum : %d
", ntohs(tcpheader->checksum));
    fprintf(logfile, " |-Urgent Pointer : %d
", tcpheader->urgent_pointer);
    fprintf(logfile, "
");
    fprintf(logfile, " DATA Dump ");
    fprintf(logfile, "
");

    fprintf(logfile, "IP Header
");
    PrintData(Buffer, iphdrlen);

    fprintf(logfile, "TCP Header
");
    PrintData(Buffer + iphdrlen, tcpheader->data_offset * 4);

    fprintf(logfile, "Data Payload
");
    PrintData(Buffer + iphdrlen + tcpheader->data_offset * 4
        , (Size - tcpheader->data_offset * 4 - iphdr->ip_header_len * 4));

    fprintf(logfile, "
###########################################################");
}

void PrintUdpPacket(char* Buffer, int Size)
{
    unsigned short iphdrlen;

    iphdr = (IPV4_HDR*)Buffer;
    iphdrlen = iphdr->ip_header_len * 4;

    udpheader = (UDP_HDR*)(Buffer + iphdrlen);

    fprintf(logfile, "

***********************UDP Packet*************************
");

    PrintIpHeader(Buffer);

    fprintf(logfile, "
UDP Header
");
    fprintf(logfile, " |-Source Port : %d
", ntohs(udpheader->source_port));
    fprintf(logfile, " |-Destination Port : %d
", ntohs(udpheader->dest_port));
    fprintf(logfile, " |-UDP Length : %d
", ntohs(udpheader->udp_length));
    fprintf(logfile, " |-UDP Checksum : %d
", ntohs(udpheader->udp_checksum));

    fprintf(logfile, "
");
    fprintf(logfile, "IP Header
");

    PrintData(Buffer, iphdrlen);

    fprintf(logfile, "UDP Header
");

    PrintData(Buffer + iphdrlen, sizeof(UDP_HDR));

    fprintf(logfile, "Data Payload
");

    PrintData(Buffer + iphdrlen + sizeof(UDP_HDR), (Size - sizeof(UDP_HDR) - iphdr->ip_header_len * 4));

    fprintf(logfile, "
###########################################################");
}


/*
    Print the hex values of the data
*/
void PrintData(char* data, int Size)
{
    char a, line[17], c;
    int j;

    //loop over each character and print
    for (i = 0; i < Size; i++)
    {
        c = data[i];

        //Print the hex value for every character , with a space. Important to make unsigned
        fprintf(logfile, " %.2x", (unsigned char)c);

        //Add the character to data line. Important to make unsigned
        a = (c >= 32 && c <= 128) ? (unsigned char)c : '.';

        line[i % 16] = a;

        //if last character of a line , then print the line - 16 characters in 1 line
        if ((i != 0 && (i + 1) % 16 == 0) || i == Size - 1)
        {
            line[i % 16 + 1] = '';

            //print a big gap of 10 characters between hex and characters
            fprintf(logfile, "          ");

            //Print additional spaces for last lines which might be less than 16 characters in length
            for (j = strlen(line); j < 16; j++)
            {
                fprintf(logfile, "   ");
            }

            fprintf(logfile, "%s 
", line);
        }
    }

    fprintf(logfile, "
");
}

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