// Module Name: Ping.c
//
// Description:
//    This sample illustrates how an ICMP ping app can be written
//    using the SOCK_RAW socket type and IPPROTO_ICMP protocol.
//    By creating a raw socket, the underlying layer does not change
//    the protocol header so that when we submit the ICMP header
//    nothing is changed so that the receiving end will see an 
//    ICMP packet. Additionally, we use the record route IP option
//    to get a round trip path to the endpoint. Note that the size
//    of the IP option header that records the route is limited to
//    nine IP addresses.
//
// Compile:
//     cl -o Ping Ping.c ws2_32.lib /Zp1
//
// Command Line Options/Parameters:
//     Ping [host] [packet-size]
//     
//     host         String name of host to ping
//     packet-size  Integer size of packet to send 
//                      (smaller than 1024 bytes)
//
//#pragma pack(1)

#define WIN32_LEAN_AND_MEAN
#include <winsock2.h>
#include <ws2tcpip.h>
#include <stdio.h>
#include <stdlib.h>

#define IP_RECORD_ROUTE  0x7
// 
// IP header structure
//
typedef struct _iphdr 
{
    unsigned int   h_len:4;        // Length of the header
    unsigned int   version:4;      // Version of IP
    unsigned char  tos;            // Type of service
    unsigned short total_len;      // Total length of the packet
    unsigned short ident;          // Unique identifier
    unsigned short frag_and_flags; // Flags
    unsigned char  ttl;            // Time to live
    unsigned char  proto;          // Protocol (TCP, UDP etc)
    unsigned short checksum;       // IP checksum

    unsigned int   sourceIP;
    unsigned int   destIP;
} IpHeader;

#define ICMP_ECHO        8
#define ICMP_ECHOREPLY   0
#define ICMP_MIN         8 // Minimum 8-byte ICMP packet (header)

//
// ICMP header structure
//
typedef struct _icmphdr 
{
    BYTE   i_type;
    BYTE   i_code;                 // Type sub code
    USHORT i_cksum;
    USHORT i_id;
    USHORT i_seq;
    // This is not the standard header, but we reserve space for time
    ULONG  timestamp;
} IcmpHeader;

//
// IP option header - use with socket option IP_OPTIONS
//
typedef struct _ipoptionhdr
{
    unsigned char        code;        // Option type
    unsigned char        len;         // Length of option hdr
    unsigned char        ptr;         // Offset into options
    unsigned long        addr[9];     // List of IP addrs
} IpOptionHeader;

#define DEF_PACKET_SIZE  32        // Default packet size
#define MAX_PACKET       1024      // Max ICMP packet size
#define MAX_IP_HDR_SIZE  60        // Max IP header size w/options

BOOL  bRecordRoute;
int   datasize;
char *lpdest;

//
// Function: usage
//
// Description:
//    Print usage information
//
void usage(char *progname)
{
    printf("usage: ping -r <host> [data size]\n");
    printf("       -r           record route\n");
    printf("        host        remote machine to ping\n");
    printf("        datasize    can be up to 1KB\n");
    ExitProcess(-1);
}

// 
// Function: FillICMPData
//
// Description:
//    Helper function to fill in various fields for our ICMP request
//
void FillICMPData(char *icmp_data, int datasize)
{
    IcmpHeader *icmp_hdr = NULL;
    char       *datapart = NULL;

    icmp_hdr = (IcmpHeader*)icmp_data;
    icmp_hdr->i_type = ICMP_ECHO;        // Request an ICMP echo
    icmp_hdr->i_code = 0;
    icmp_hdr->i_id = (USHORT)GetCurrentProcessId();
    icmp_hdr->i_cksum = 0;
    icmp_hdr->i_seq = 0;
  
    datapart = icmp_data + sizeof(IcmpHeader);
    //
    // Place some junk in the buffer
    //
    memset(datapart,'E', datasize - sizeof(IcmpHeader));
}

// 
// Function: checksum
//
// Description:
//    This function calculates the 16-bit one's complement sum
//    of the supplied buffer (ICMP) header
//
USHORT checksum(USHORT *buffer, int size) 
{
    unsigned long cksum=0;

    while (size > 1) 
    {
        cksum += *buffer++;
        size -= sizeof(USHORT);
    }
    if (size) 
    {
        cksum += *(UCHAR*)buffer;
    }
    cksum = (cksum >> 16) + (cksum & 0xffff);
    cksum += (cksum >>16);
    return (USHORT)(~cksum);
}

//
// Function: DecodeIPOptions
//
// Description:
//    If the IP option header is present, find the IP options
//    within the IP header and print the record route option
//    values
//
void DecodeIPOptions(char *buf, int bytes)
{
    IpOptionHeader *ipopt = NULL;
    IN_ADDR         inaddr;
    int             i;
    HOSTENT        *host = NULL;

    ipopt = (IpOptionHeader *)(buf + 20);

    printf("RR:   ");
    for(i = 0; i < (ipopt->ptr / 4) - 1; i++)
    {
        inaddr.S_un.S_addr = ipopt->addr[i];
        if (i != 0)
            printf("      ");
        host = gethostbyaddr((char *)&inaddr.S_un.S_addr,
                    sizeof(inaddr.S_un.S_addr), AF_INET);
        if (host)
            printf("(%-15s) %s\n", inet_ntoa(inaddr), host->h_name);
        else
            printf("(%-15s)\n", inet_ntoa(inaddr));
    }
    return;
}

//
// Function: DecodeICMPHeader
//
// Description:
//    The response is an IP packet. We must decode the IP header to
//    locate the ICMP data.
//
void DecodeICMPHeader(char *buf, int bytes, 
    struct sockaddr_in *from)
{
    IpHeader       *iphdr = NULL;
    IcmpHeader     *icmphdr = NULL;
    unsigned short  iphdrlen;
    DWORD           tick;
    static   int    icmpcount = 0;

    iphdr = (IpHeader *)buf;
	// Number of 32-bit words * 4 = bytes
    iphdrlen = iphdr->h_len * 4;
    tick = GetTickCount();

    if ((iphdrlen == MAX_IP_HDR_SIZE) && (!icmpcount))
        DecodeIPOptions(buf, bytes);

    if (bytes  < iphdrlen + ICMP_MIN) 
    {
        printf("Too few bytes from %s\n", 
            inet_ntoa(from->sin_addr));
    }
    icmphdr = (IcmpHeader*)(buf + iphdrlen);

    if (icmphdr->i_type != ICMP_ECHOREPLY) 
    {
        printf("nonecho type %d recvd\n", icmphdr->i_type);
        return;
    }
    // Make sure this is an ICMP reply to something we sent!
    //
    if (icmphdr->i_id != (USHORT)GetCurrentProcessId()) 
    {
        printf("someone else's packet!\n");
        return ;
    }
    printf("%d bytes from %s:", bytes, inet_ntoa(from->sin_addr));
    printf(" icmp_seq = %d. ", icmphdr->i_seq);
    printf(" time: %d ms", tick - icmphdr->timestamp);
    printf("\n");

    icmpcount++;
    return;
}

void ValidateArgs(int argc, char **argv)
{
    int                i;

    bRecordRoute = FALSE;
    lpdest = NULL;
    datasize = DEF_PACKET_SIZE;
    
    for(i = 1; i < argc; i++)
    {
        if ((argv[i][0] == '-') || (argv[i][0] == '/'))
        {
            switch (tolower(argv[i][1]))
            {
                case 'r':        // Record route option
                    bRecordRoute = TRUE;
                    break;
                default:
                    usage(argv[0]);
                    break;
            }
        }
        else if (isdigit(argv[i][0]))
            datasize = atoi(argv[i]);
        else
            lpdest = argv[i];
    }
}
        
//
// Function: main
//
// Description:
//    Setup the ICMP raw socket, and create the ICMP header. Add
//    the appropriate IP option header, and start sending ICMP
//    echo requests to the endpoint. For each send and receive,
//    we set a timeout value so that we don't wait forever for a 
//    response in case the endpoint is not responding. When we
//    receive a packet decode it.
//
int main(int argc, char **argv)
{

    WSADATA            wsaData;
    SOCKET             sockRaw = INVALID_SOCKET;
    struct sockaddr_in dest,
                       from;
    int                bread,
                       fromlen = sizeof(from),
                       timeout = 1000,
                       ret;
    char              *icmp_data = NULL,
                      *recvbuf = NULL;
    unsigned int       addr = 0;
    USHORT             seq_no = 0;
    struct hostent    *hp = NULL;
    IpOptionHeader     ipopt;


    if (WSAStartup(MAKEWORD(2, 2), &wsaData) != 0)
    {
        printf("WSAStartup() failed: %d\n", GetLastError());
        return -1;
    }
    ValidateArgs(argc, argv);

    //
    // WSA_FLAG_OVERLAPPED flag is required for SO_RCVTIMEO, 
    // SO_SNDTIMEO option. If NULL is used as last param for 
    // WSASocket, all I/O on the socket is synchronous, the 
    // internal user mode wait code never gets a chance to 
    // execute, and therefore kernel-mode I/O blocks forever. 
    // A socket created via the socket function has the over-
	 // lapped I/O attribute set internally. But here we need 
	 // to use WSASocket to specify a raw socket.
    //
    // If you want to use timeout with a synchronous 
    // nonoverlapped socket created by WSASocket with last 
	 // param set to NULL, you can set the timeout by using 
	 // the select function, or you can use WSAEventSelect and 
	 // set the timeout in the WSAWaitForMultipleEvents 
	 // function.
    //
    sockRaw = WSASocket (AF_INET, SOCK_RAW, IPPROTO_ICMP, NULL, 0,
                         WSA_FLAG_OVERLAPPED);
    if (sockRaw == INVALID_SOCKET) 
    {
        printf("WSASocket() failed: %d\n", WSAGetLastError());
        return -1;
    }
    if (bRecordRoute)
    {
        // Setup the IP option header to go out on every ICMP packet
        //
        ZeroMemory(&ipopt, sizeof(ipopt));
        ipopt.code = IP_RECORD_ROUTE; // Record route option
        ipopt.ptr  = 4;               // Point to the first addr offset
        ipopt.len  = 39;              // Length of option header
  
        ret = setsockopt(sockRaw, IPPROTO_IP, IP_OPTIONS, 
            (char *)&ipopt, sizeof(ipopt));
        if (ret == SOCKET_ERROR)
        {
            printf("setsockopt(IP_OPTIONS) failed: %d\n", 
                WSAGetLastError());
        }
    }
    // Set the send/recv timeout values
    //
    bread = setsockopt(sockRaw, SOL_SOCKET, SO_RCVTIMEO, 
                (char*)&timeout, sizeof(timeout));
    if(bread == SOCKET_ERROR) 
    {
        printf("setsockopt(SO_RCVTIMEO) failed: %d\n", 
            WSAGetLastError());
        return -1;
    }
    timeout = 1000;
    bread = setsockopt(sockRaw, SOL_SOCKET, SO_SNDTIMEO, 
                (char*)&timeout, sizeof(timeout));
    if (bread == SOCKET_ERROR) 
    {
        printf("setsockopt(SO_SNDTIMEO) failed: %d\n", 
            WSAGetLastError());
        return -1;
    }
    memset(&dest, 0, sizeof(dest));
    //
    // Resolve the endpoint's name if necessary
    //
    dest.sin_family = AF_INET;
    if ((dest.sin_addr.s_addr = inet_addr(lpdest)) == INADDR_NONE)
    {
        if ((hp = gethostbyname(lpdest)) != NULL)
        {
            memcpy(&(dest.sin_addr), hp->h_addr, hp->h_length);
            dest.sin_family = hp->h_addrtype;
            printf("dest.sin_addr = %s\n", inet_ntoa(dest.sin_addr));
        }
        else
        {
            printf("gethostbyname() failed: %d\n", 
                WSAGetLastError());
            return -1;
        }
    }        

    // 
    // Create the ICMP packet
    //       
    datasize += sizeof(IcmpHeader);  

    icmp_data = HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY,
                  MAX_PACKET);
    recvbuf = HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY,
                  MAX_PACKET);
    if (!icmp_data) 
    {
        printf("HeapAlloc() failed: %d\n", GetLastError());
        return -1;
    }
    memset(icmp_data,0,MAX_PACKET);
    FillICMPData(icmp_data,datasize);
    //
    // Start sending/receiving ICMP packets
    //
    while(1) 
    {
        static int nCount = 0;
        int        bwrote;
                
        if (nCount++ == 4) 
            break;
                
        ((IcmpHeader*)icmp_data)->i_cksum = 0;
        ((IcmpHeader*)icmp_data)->timestamp = GetTickCount();
        ((IcmpHeader*)icmp_data)->i_seq = seq_no++;
        ((IcmpHeader*)icmp_data)->i_cksum = 
            checksum((USHORT*)icmp_data, datasize);

        bwrote = sendto(sockRaw, icmp_data, datasize, 0, 
                     (struct sockaddr*)&dest, sizeof(dest));
        if (bwrote == SOCKET_ERROR)
        {
            if (WSAGetLastError() == WSAETIMEDOUT) 
            {
                printf("timed out\n");
                continue;
            }
            printf("sendto() failed: %d\n", WSAGetLastError());
            return -1;
        }
        if (bwrote < datasize) 
        {
            printf("Wrote %d bytes\n", bwrote);
        }
        bread = recvfrom(sockRaw, recvbuf, MAX_PACKET, 0, 
                    (struct sockaddr*)&from, &fromlen);
        if (bread == SOCKET_ERROR)
        {
            if (WSAGetLastError() == WSAETIMEDOUT) 
            {
                printf("timed out\n");
                continue;
            }
            printf("recvfrom() failed: %d\n", WSAGetLastError());
            return -1;
        }
        DecodeICMPHeader(recvbuf, bread, &from);

        Sleep(1000);
    }
    // Cleanup
    //
    if (sockRaw != INVALID_SOCKET) 
        closesocket(sockRaw);
    HeapFree(GetProcessHeap(), 0, recvbuf);
    HeapFree(GetProcessHeap(), 0, icmp_data);

    WSACleanup();
    return 0;
}