datagram.c

一个功能精简的TCP/IP协议栈

/* UDP datagram utility for 'TCP/IP Lean' (c) Iosoft Ltd. 2000

This software is only licensed for distribution with the book 'TCP/IP Lean',
and may only be used for personal experimentation by the purchaser
of that book, on condition that this copyright notice is retained.
For commercial licensing, contact [e-mail]

This is experimental software; use it entirely at your own risk. The author
offers no warranties of any kind, including its fitness for purpose. */

/*
** v0.01 JPB 10/2/00
** v0.02 JPB 10/2/00  Added ICMP message for unreachable ports
** v0.03 JPB 15/2/00  Changed to command-line interface
** v0.04 JPB 7/4/00   Initial TFTP work
** v0.05 JPB 7/4/00   Removed TFTP stuff, added binary mode and file I/P
** v0.06 JPB 3/7/00   Changed default config file to TCPLEAN.CFG
**                    Revised header for book CD
**                    Fixed bug in SLIP option (was sending ARP!)
*/

#define VERSION "0.06"

#include <stdio.h>
#include <ctype.h>
#include <stdlib.h>
#include <string.h>
#include <conio.h>
#include <signal.h>
#include <time.h>

#include "ether.h"
#include "netutil.h"
#include "net.h"
#include "ip.h"
#include "udp.h"

#define CFGFILE     "tcplean.cfg"   /* Default config filename */
#define CFGEXT      ".cfg"          /* Default config extension */
#define MAXNETCFG   40              /* Max length of a net config string */
#define DEFPORT     DAYPORT         /* Default port number */
#define ARPTIME     1000            /* ARP retry timer (msec) */
#define COMMANDLEN  80
#define TRYTIME     1000
#define MAXTRIES    5

#define ARP_TX      1               /* Client state: sending ARP */
#define ARP_RX      2               /*               received ARP */
#define CLIENT_DONE 3               /*               completed */

GENFRAME genframe;                  /* Frame for network Tx/Rx */
char cfgfile[MAXPATH+5]=CFGFILE;    /* Config filename */
char netcfg[MAXNETCFG+1]="??";      /* Network config string */
extern BYTE bcast[MACLEN];          /* Broadcast Ethernet addr */
extern BYTE zermac[MACLEN];         /* All-zero MAC addr */
NODE  locnode;                      /* My Ethernet and IP addresses */
NODE remnode;                       /* Remote node */
WORD remport;                       /* Remote port number */
int breakflag;                      /* Flag to indicate ctrl-break pressed */
int client;                         /* Flag to indicate client is active */
int binmode;                        /* Flag to enable binary mode */
char infile[MAXPATH+1];             /* Filename for I/P data */

/* Debug flags */
extern int netdebug;                /* Net packet display */
extern int udpdebug;                /* UDP frame display */

/* Function pointer: upcall from TCP/IP stack */
extern NODE *(*get_locnode_n)(int n);           /* Get local node */

/* Prototypes */
WORD read_netconfig(char *fname, NODE *np);
NODE *locnode_n(int n);
int do_receive(GENFRAME *gfp);
int udp_receive(GENFRAME *gfp, int len);
void udp_transmit(GENFRAME *gfp, NODE *sp, NODE *dp, void *dat, int len);
void udp_transmit_file(GENFRAME *gfp, NODE *sp, NODE *dp, FILE *in);
void do_poll(GENFRAME *gfp);
void disp_usage(void);
void disp_data(BYTE *data, int len);
WORD str2service(char *str);
void break_handler(int sig);

int main(int argc, char *argv[])
{
    int args=0, err=0, tries=0, st, cstate=ARP_TX, lastcstate=0;
    char c, *p, temps[18], *cmd="";
    WORD dtype;
    GENFRAME *gfp;
    LWORD mstime;
    FILE *in=0;

    printf("DATAGRAM v" VERSION "\n");          /* Sign on */
    get_locnode_n = locnode_n;                  /* Set upcall ptr to func */
    signal(SIGINT, break_handler);              /* Trap ctrl-C */
    remnode.port = DEFPORT;                     /* Preset remote port number */
    locnode.port = MINEPORT;
    while (argc > ++args)                       /* Process command-line args */
    {
        if ((c=argv[args][0]) == '-')
        {
            switch (toupper(argv[args][1]))
            {
            case 'B':                           /* -B: binary mode */
                binmode = 1;
                break;
            case 'C':                           /* -C: config filename */
                strncpy(cfgfile, argv[++args], MAXPATH);
                if ((p=strrchr(cfgfile, '.'))==0 || !isalpha(*(p+1)))
                    strcat(cfgfile, CFGEXT);
                break;
            case 'I':                           /* -I: filename for data in*/
                strncpy(infile, argv[++args], MAXPATH);
                break;
            case 'U':                           /* -U: display UDP segments */
                udpdebug = 1;
                break;
            case 'V':                           /* -V: verbose packet display */
                netdebug |= 1;
                break;
            case 'X':                           /* -X: hex packet display */
                netdebug |= 2;
                break;
            default:
                err = 1;
            }
        }
        else if (client==0 && isdigit(c))       /* If client mode.. */
        {
            remnode.ip = atoip(argv[args]);     /* Get destination IP address */
            client++;
        }
        else if (client==1)
        {
            if ((remport=str2service(argv[args]))!=0)
                remnode.port = remport;         /* ..then port number */
            else
            {
                printf("Unrecognised port number/service '%s'\n", argv[args]);
                err++;
            }
            client++;
        }
        else if (client == 2)
        {
            cmd = argv[args];                   /* ..then command string */
            client++;
        }
    }
    if (err)                                    /* Prompt user if error */
        disp_usage();
    else if (!(dtype=read_netconfig(cfgfile, &locnode)))
        printf("Invalid configuration '%s'\n", cfgfile);
    else if (*infile && (in=fopen(infile, "rb"))==0)
        printf("Can't open data I/P file '%s'\n", infile);
    else
    {
        remnode.dtype = genframe.g.dtype = dtype;   /* Set frame driver type */
        gfp = &genframe;                            /* Get pointer to frame */
        printf("IP %s", ipstr(locnode.ip, temps));
        printf(" mask %s", ipstr(locnode.mask, temps));
        if (locnode.gate)
            printf(" gate %s", ipstr(locnode.gate, temps));
        if (dtype & DTYPE_ETHER)
            printf(" Ethernet %s", ethstr(locnode.mac, temps));
        else if (dtype & DTYPE_SLIP)
            cstate = ARP_RX;
        printf("\nPress ESC or ctrl-C to exit\n");
        if (client)
        {
            printf("Contacting %s...\n\n", ipstr(remnode.ip, temps));
            memcpy(remnode.mac, bcast, MACLEN);
        }
        mstimeout(&mstime, 0);
        while (!breakflag)                      /* Main loop.. */
        {
            if (client && (mstimeout(&mstime, TRYTIME) || cstate!=lastcstate))
            {
                if (tries++ > MAXTRIES)         /* Giving up? */
                    breakflag = 1;
                else if (cstate == ARP_TX)      /* (Re)transmit ARP? */
                    put_frame(gfp, make_arp(gfp, &locnode, &remnode, ARPREQ));
                else if (cstate == ARP_RX)      /* ARP response? */
                {
                    if (in)
                        udp_transmit_file(gfp, &locnode, &remnode, in);
                    else
                        udp_transmit(gfp, &locnode, &remnode, cmd, strlen(cmd));
                }
                else if (cstate == CLIENT_DONE) /* UDP response? */
                    breakflag = 1;
                lastcstate = cstate;            /* Record state-change */
            }
            st = do_receive(gfp);               /* Receive frames */
            cstate = st ? st : cstate;          /* ..maybe change state */
            do_poll(gfp);                       /* Poll net drivers */
            if (kbhit() && getch()==0x1b)       /* Check keyboard */
                breakflag = 1;
        }
        close_net(dtype);                       /* Shut down net driver */
    }
    if (in)
        fclose(in);
    return(0);
}

/* Read network config file to get IP address netmask and gateway
** Return driver type, 0 if error */
WORD read_netconfig(char *fname, NODE *np)
{
    char temps[31];
    WORD dtype=0;
    BYTE b;

    if (read_cfgstr(fname, "net", netcfg, MAXNETCFG))
    {                                               /* Get IP address */
        if (!read_cfgstr(fname, "ip", temps, 30) || (np->ip=atoip(temps))==0)
            printf("No IP address\n");
        else if (!(dtype = open_net(netcfg)))       /* Open net driver */