tftpc.c

tftp-1.0源码

/**********************************************************
Date: 		NOV 28th, 2006
Project :	TFTP Client
Programers:	
Jonathan Felske
Andrew Fullard 
Craig Holmes
Reza Rahmanian 
Adam Tomalty 
File:		TFTP Client (main)
Purpose:	A TFTP client that will request a connections from
		the server and transefet files.
Notes:		Here we are using the sendto and recvfrom
		functions so the server and client can exchange data.
***********************************************************/

#include "tftp.h"

/*a function to print the Help menu*/
void help (char *);
/*a function to create the request packet, read or write*/
int req_packet (int opcode, char *filename, char *mode, char buf[]);
/*a function to creat an ACK packet*/
int ack_packet (int block, char buf[]);
/*a function to create the Error packets*/
int err_packet (int err_code, char *err_msg, char buf[]);
/*a function that will print the ip:port pair of the server or client, plus data sent or recieved*/
void ip_port (struct sockaddr_in host);
/*a function to send a file to the server*/
void tsend (char *pFilename, struct sockaddr_in server, char *pMode,
	    int sock);
/*a function to get a file from the server*/
void tget (char *pFilename, struct sockaddr_in server, char *pMode, int sock);


/* default values which can be controlled by command line */
char path[64] = "/tmp/";
int port = 69;
unsigned short int ackfreq = 1;
int datasize = 512;
int debug = 0, w_size = 1, p_length = 512;


int
main (int argc, char **argv)
{
    /*local variables */
    extern char *optarg;
    int sock, server_len, len, opt;	//,n;
    char opcode, filename[196], mode[12] = "octet";
    struct hostent *host;		/*for host information */
    struct sockaddr_in server;	//, client; /*the address structure for both the server and client */
    FILE *fp;			/*a pointer to a file that the client will send or get from the server */

    if (argc < 2)
    {
        help (argv[0]);
        return 0;
    }
    if (!(host = gethostbyname (argv[1])))
    {
        perror ("Client could not get host address information");
        exit (2);
    }

    /* All of the following deals with command line switches */
    while ((opt = getopt (argc, argv, "dnoh:P:p:g:l:w:")) != -1)	/* this function is handy */
    {
        switch (opt)
        {
            case 'd':		/* debug mode (no opts) */
                debug = 1;
                break;
            case 'P':		/* Port (opt required) */
                port = atoi (optarg);
                if (debug)
                {
                    printf ("Client: The port number is: %d\n", port);
                }
                break;
            case 'p':		/* put a file on the server */
                strncpy (filename, optarg, sizeof (filename) - 1);
                opcode = WRQ;
                fp = fopen (filename, "r");	/*opened the file for reading */
                if (fp == NULL)
                {
                    printf ("Client: file could not be opened\n");
                    return 0;
                }
                if (debug)
                {
                    printf ("Client: The file name is: %s and can be read",
                            filename);
                }
                fclose (fp);
                break;
            case 'g':		/*get a file from the server */
                strncpy (filename, optarg, sizeof (filename) - 1);
                opcode = RRQ;
                fp = fopen (filename, "w");	/*opened the file for writting */
                if (fp == NULL)
                {
                    printf ("Client: file could not be created\n");
                    return 0;
                }
                if (debug)
                {
                    printf ("Client: The file name is: %s and it has been created",
                            filename);
                }
                fclose (fp);
                break;
            case 'w':		/* Get the window size */
                ackfreq = atoi (optarg);
                if (debug)
                {
                    printf ("Client: Window size is: %i\n", ackfreq);
                }
                //ackfreq = atoi (optarg);
                if (ackfreq > MAXACKFREQ)
                {
                    printf
                        ("Client: Sorry, you specified an ack frequency higher than the maximum allowed (Requested: %d Max: %d)\n",
                         ackfreq, MAXACKFREQ);
                    return 0;
                }
                else if (w_size == 0)
                {
                    printf ("Client: Sorry, you have to ack sometime.\n");
                    return 0;
                }
                break;
            case 'l':		/* packet length */
                datasize = atoi (optarg);
                if (debug)
                {
                    printf ("Client: Packet length is: %i bytes\n", datasize);
                }
                if (datasize > MAXDATASIZE)
                {
                    printf
                        ("Client: Sorry, you specified a data size higher than the maximum allowed (Requested: %d Max: %d)\n",
                         datasize, MAXDATASIZE);
                    return 0;
                }
                break;
            case 'h':		/* Help (no opts) */
                help (argv[0]);
                return (0);
                break;
            case 'o':
                strncpy (mode, "octet", sizeof (mode) - 1);
                if (debug)
                {
                    printf ("Client: The mode is set to octet\n");
                }
                break;
            case 'n':
                strncpy (mode, "netascii", sizeof (mode) - 1);
                if (debug)
                {
                    printf ("Client: The mode is set to netascii\n");
                }
                break;
            default:		/* everything else */
                help (argv[0]);
                return (0);
                break;
        }			//end of switch
    }				//end of while loop

    /*check for valid input*/
    if (argc < 5 || argc > 12)
    {
        printf ("Client: wrong number of arguments: %d\n", argc);
        help (argv[0]);
        exit (ERROR);
    }

    /* Done dealing with switches and the command line*/


    /*Create the socket, a -1 will show us an error */
    if ((sock = socket (AF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0)
    {
        printf ("Client: Socket could not be created");
        return 0;
    }


    /*set the address values for the server */
    memset (&server, 0, sizeof (server));	/*Clear the structure */
    server.sin_family = AF_INET;	/*address family for TCP and UDP */
    memcpy (&server.sin_addr, host->h_addr, host->h_length);	/*set address of server taken from gethostbyname function */
    //server.sin_addr.s_addr = htonl (INADDR_ANY); /*use any address */
    server.sin_port = htons (port);	/*pick a free port */


    server_len = sizeof (server);	/*get the length of the server address */

    if (debug)
        printf ("Client: size of server_address is : %d bytes\n", server_len);

    memset (buf, 0, BUFSIZ);	/*clear the buffer */
    /* this is the first request message */
    len = req_packet (opcode, filename, mode, buf);

    if (debug)
        printf ("Client: The request packt's length is: %d bytes\n", len);

    if (sendto (sock, buf, len, 0, (struct sockaddr *) &server, server_len) !=
            len)
    {
        perror ("Client: sendto has returend an error");
        exit (ERROR);
    }
    if (debug)
        ip_port (server);
    switch (opcode)
    {
        case RRQ:			/*read from the server, download */
            tget (filename, server, mode, sock);
            break;
        case WRQ:			/*write to the server, upload */
            tsend (filename, server, mode, sock);
            break;
        default:
            printf ("Invalid opcode detected. Ignoring packet.");
    }
    close (sock);			/* close the socket */
    return 1;
}				//end of main


/******************************************************************
		Function deffinitions
*******************************************************************/

/*usage of the command:
./tftpc server -P port# -g(get file)|-p(put file) <filename> -w (window size) -l (packetlength)
if windowsize and packet length are not chosen then a default value of 1, for the
window size and 512 bytes for the packet length will be set.*/
/* a function to display the help menu*/
void
help (char *app)
{
    printf
        ("Usage:\n%s server [-h] [-d] [-P port] [-g] | [-p] [file-name] [-w size] [-l length] [-o] [-n]\n",
         app);
    printf
        ("Options:\n-h (help; this message)\n-d (Debug mode)\n-P port(Port number default is 69)\n-g (get a file from the server)\n-p (send a file to the server)\n");
    printf
        ("-w size (set window size, default is 1)\n-l len (set max packet length, default is 512 bytes)\n");
    printf
        ("-o for octet file transfer (default).\n-n for netascii file transfer\n");
}

/* A function that will create a request packet*/
/*I'm not sure if I need the last 0x00 because sprintf will end the string with \0*/
int
req_packet (int opcode, char *filename, char *mode, char buf[])
{
    int len;
    len =
        sprintf (buf, "%c%c%s%c%s%c", 0x00, opcode, filename, 0x00, mode, 0x00);
    if (len == 0)
    {
        printf ("Error in creating the request packet\n");	/*could not print to the client buffer */
        exit (ERROR);
    }
    if (debug)
    {
        printf ("I am creating the request packet.\n");
    }
    return len;
}



/* A function that will create an ACK packet*/
/*problem that we will have here is that we can only get up to 255 blocks*/
int
ack_packet (int block, char buf[])
{
    int len;
    len = sprintf (buf, "%c%c%c%c", 0x00, ACK, 0x00, 0x00);
    buf[2] = (block & 0xFF00) >> 8;
    buf[3] = (block & 0x00FF);
    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 the ACK packet.\n");
    }
    return len;
}


/* A function that will create an error packet based on the error code*/
int
err_packet (int err_code, char *err_msg, char buf[])
{
    int len;