tftpc.c

tftp-1.0源码

    memset (buf, 0, sizeof (buf));
    len =
        sprintf (buf, "%c%c%c%c%s%c", 0x00, ERR, 0x00, err_code, err_msg, 0x00);
    if (len == 0)
    {
        printf ("Error in creating the ACK packet\n");	/*could not print to the client buffer */
        exit (ERROR);
    }
    if (debug)
    {
        printf ("I am creating an ERROR packet.\n");
    }
    return len;
}

/* A function used for debuging to show the port numbers used*/
void
ip_port (struct sockaddr_in host)
{
    printf ("The IP port pair for the host is: IP:%s Port:%d \n",
            inet_ntoa (host.sin_addr), ntohs (host.sin_port));
}

/*
*This function is called when the client would like to upload a file to the server.
*/
void
tsend (char *pFilename, struct sockaddr_in server, char *pMode, int sock)
{
    int len, server_len, opcode, ssize = 0, n, i, j, bcount = 0, tid;
    unsigned short int count = 0, rcount = 0, acked = 0;
    unsigned char filebuf[MAXDATASIZE + 1];
    unsigned char packetbuf[MAXACKFREQ][MAXDATASIZE + 12],
                  recvbuf[MAXDATASIZE + 12];
    char filename[128], mode[12], *bufindex;	//fullpath[196],
    struct sockaddr_in ack;

    FILE *fp;			/* pointer to the file we will be sending */

    strcpy (filename, pFilename);	//copy the pointer to the filename into a real array
    strcpy (mode, pMode);		//same as above

    if (debug)
        printf ("Client: branched to file send function\n");

    /*At this point I have to wait to recieve an ACK from the server before I start sending the file*/
    /*open the file to read */
    fp = fopen (filename, "r");
    if (fp == NULL)
    {				//if the pointer is null then the file can't be opened - Bad perms OR no such file
        if (debug)
            printf ("Client: sending bad file: file not found (%s)\n", filename);
        return;
    }
    else
    {
        if (debug)
            printf ("Client: Sending file... (source: %s)\n", filename);

    }
    //get ACK for WRQ
    /* The following 'for' loop is used to recieve/timeout ACKs */
    for (j = 0; j < RETRIES - 2; j++)
    {
        server_len = sizeof (ack);
        errno = EAGAIN;
        n = -1;
        for (i = 0; errno == EAGAIN && i <= TIMEOUT && n < 0; i++)
        {
            n = recvfrom (sock, recvbuf, sizeof (recvbuf), MSG_DONTWAIT,
                    (struct sockaddr *) &ack, (socklen_t *) & server_len);
            usleep (1000);
        }


        /* if(debug)
           ip_port (ack);    print the vlaue recived from the server */


        tid = ntohs (ack.sin_port);	//get the tid of the server.
        server.sin_port = htons (tid);	//set the tid for rest of the transfer


        if (n < 0 && errno != EAGAIN)
        {
            if (debug)
                printf
                    ("Client: could not receive from the server (errno: %d n: %d)\n",
                     errno, n);
            //resend packet
        }
        else if (n < 0 && errno == EAGAIN)
        {
            if (debug)
                printf ("Client: Timeout waiting for ack (errno: %d n: %d)\n",
                        errno, n);
            //resend packet
        }
        else
        {			/*changed client to server here */
            if (server.sin_addr.s_addr != ack.sin_addr.s_addr)	/* checks to ensure send to ip is same from ACK IP */
            {
                if (debug)
                    printf
                        ("Client: Error recieving ACK (ACK from invalid address)\n");
                j--;		/* in this case someone else connected to our port. Ignore this fact and retry getting the ack */
                continue;
            }
            if (tid != ntohs (server.sin_port))	/* checks to ensure get from the correct TID */
            {
                if (debug)
                    printf
                        ("Client: Error recieving file (data from invalid tid)\n");
                len = err_packet (5, err_msg[5], buf);
                if (sendto (sock, buf, len, 0, (struct sockaddr *) &server, sizeof (server)) != len)	/* send the data packet */
                {
                    printf
                        ("Client: Mismatch in number of sent bytes while trying to send mode error packet\n");
                }
                /* if (debug)
                   ip_port(server); */
                j--;
                continue;		/* we aren't going to let another connection spoil our first connection */
            }

            /* this formatting code is just like the code in the main function */
            bufindex = (char *) recvbuf;	//start our pointer going
            if (bufindex++[0] != 0x00)
                printf ("Client: bad first nullbyte!\n");
            opcode = *bufindex++;

            rcount = *bufindex++ << 8;
            rcount &= 0xff00;
            rcount += (*bufindex++ & 0x00ff);
            if (opcode != 4 || rcount != count)	/* ack packet should have code 4 (ack) and should be acking the packet we just sent */
            {
                if (debug)
                    printf
                        ("Client: Remote host failed to ACK proper data packet # %d (got OP: %d Block: %d)\n",
                         count, opcode, rcount);
                /* sending error message */
                if (opcode > 5)
                {

                    len = err_packet (4, err_msg[4], buf);
                    if (sendto (sock, buf, len, 0, (struct sockaddr *) &server, sizeof (server)) != len)	/* send the data packet */
                    {
                        printf
                            ("Client: Mismatch in number of sent bytes while trying to send mode error packet\n");
                    }
                }
                /* from here we will loop back and resend */
                /* if (debug)
                   ip_port(server); */
            }
            else
            {
                if (debug)
                    printf ("Client: Remote host successfully ACK'd (#%d)\n",
                            rcount);
                break;
            }
        }			//end of else
        if (debug)
            printf ("Client: Ack(s) lost. Resending complete.\n");

    }
    /* The ack sending 'for' loop ends here */



    memset (filebuf, 0, sizeof (filebuf));	//clear the filebuf
    while (1)			/* our break statement will escape us when we are done */
    {
        acked = 0;
        ssize = fread (filebuf, 1, datasize, fp);
        if (debug)
        {
            printf
                ("The first data block has been read from the file and will be sent to the server\n");
            printf ("The size read from the file is: %d\n", ssize);
        }

        count++;			/* count number of datasize byte portions we read from the file */
        if (count == 1)		/* we always look for an ack on the FIRST packet */
            bcount = 0;
        else if (count == 2)	/* The second packet will always start our counter at zreo. This special case needs to exist to avoid a DBZ when count = 2 - 2 = 0 */
            bcount = 0;
        else
            bcount = (count - 2) % ackfreq;

        sprintf ((char *) packetbuf[bcount], "%c%c%c%c", 0x00, 0x03, 0x00, 0x00);	/* build data packet but write out the count as zero */
        memcpy ((char *) packetbuf[bcount] + 4, filebuf, ssize);
        len = 4 + ssize;
        packetbuf[bcount][2] = (count & 0xFF00) >> 8;	//fill in the count (top number first)
        packetbuf[bcount][3] = (count & 0x00FF);	//fill in the lower part of the count
        if (debug)
            printf ("Client: Sending packet # %04d (length: %d file chunk: %d)\n",
                    count, len, ssize);
        /* send the data packet */
        if (sendto
                (sock, packetbuf[bcount], len, 0, (struct sockaddr *) &server,
                 sizeof (server)) != len)
        {
            if (debug)
                printf ("Client: Mismatch in number of sent bytes\n");
            return;
        }
        if (debug)
        {
            ip_port (server);
            printf ("==count: %d  bcount: %d  ssize: %d  datasize: %d\n", count,
                    bcount, ssize, datasize);
        }
        //if ((count - 1) == 0 || ((count - 1) % ackfreq) == 0 || ssize != datasize)
        if (((count) % ackfreq) == 0 || ssize != datasize)
        {
            if (debug)
                printf ("-- I will get an ACK\n");
            /* The following 'for' loop is used to recieve/timeout ACKs */
            for (j = 0; j < RETRIES; j++)
            {
                server_len = sizeof (ack);
                errno = EAGAIN;
                n = -1;
                for (i = 0; errno == EAGAIN && i <= TIMEOUT && n < 0; i++)
                {
                    n =
                        recvfrom (sock, recvbuf, sizeof (recvbuf), MSG_DONTWAIT,
                                (struct sockaddr *) &ack,
                                (socklen_t *) & server_len);
                    /* if (debug)
                       ip_port(ack); */
                    usleep (1000);
                }
                if (n < 0 && errno != EAGAIN)
                {
                    if (debug)
                        printf
                            ("Client: could not receive from the server (errno: %d n: %d)\n",
                             errno, n);
                    //resend packet
                }
                else if (n < 0 && errno == EAGAIN)
                {
                    if (debug)
                        printf
                            ("Client: Timeout waiting for ack (errno: %d n: %d)\n",
                             errno, n);
                    //resend packet
                }
                else
                {		/* checks to ensure send to ip is same from ACK IP */
                    if (server.sin_addr.s_addr != ack.sin_addr.s_addr)
                    {
                        if (debug)
                            printf
                                ("Client: Error recieving ACK (ACK from invalid address)\n");
                        /* in this case someone else connected to our port. Ignore this fact and retry getting the ack */
                        j--;
                        continue;
                    }
                    if (tid != ntohs (server.sin_port))	/* checks to ensure get from the correct TID */
                    {
                        if (debug)
                            printf
                                ("Client: Error recieving file (data from invalid tid)\n");
                        len = err_packet (5, err_msg[5], buf);
                        /* send the data packet */
                        if (sendto
                                (sock, buf, len, 0, (struct sockaddr *) &server,
                                 sizeof (server)) != len)
                        {
                            printf
                                ("Client: Mismatch in number of sent bytes while trying to send mode error packet\n");
                        }
                        /*if (debug)
                          ip_port(server);  */
                        j--;

                        continue;	/* we aren't going to let another connection spoil our first connection */
                    }

                    /* this formatting code is just like the code in the main function */
                    bufindex = (char *) recvbuf;	//start our pointer going
                    if (bufindex++[0] != 0x00)
                        printf ("Client: bad first nullbyte!\n");
                    opcode = *bufindex++;

                    rcount = *bufindex++ << 8;
                    rcount &= 0xff00;
                    rcount += (*bufindex++ & 0x00ff);
                    if (opcode != 4 || rcount != count)	/* ack packet should have code 4 (ack) and should be acking the packet we just sent */
                    {
                        if (debug)
                            printf
                                ("Client: Remote host failed to ACK proper data packet # %d (got OP: %d Block: %d)\n",
                                 count, opcode, rcount);
                        /* sending error message */
                        if (opcode > 5)
                        {
                            len = err_packet (4, err_msg[4], buf);
                            if (sendto (sock, buf, len, 0, (struct sockaddr *) &server, sizeof (server)) != len)	/* send the data packet */
                            {
                                printf
                                    ("Client: Mismatch in number of sent bytes while trying to send mode error packet\n");