/* Network utility functions 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 license@iosoft.co.uk

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 28/10/99
** v0.02 JPB 15/11/99  Added support for Tx and Rx circular buffers
** v0.03 JPB 17/11/99  Fixed non-reentrant use of min() in circ buffer code
** v0.04 JPB 30/12/99  Added SLIP_SUPPORT option for DJGPP compatibility
** v0.05 JPB 31/12/99  Added support for IEEE 802.3 SNAP
** v0.06 JPB 7/1/00    Added 'maxlen' to net initialisation
** v0.07 JPB 17/1/00   Removed 'maxlen' again!
** v0.08 JPB 18/1/00   Moved get_frame and put_frame into this file
** v0.09 JPB 19/1/00   Added logfile
**                     Split off network functions into NET.C
** v0.10 JPB 21/3/00   Added directory search functions
** v0.11 JPB 23/3/00   Moved 'atoip' here from IP.C
** v0.12 JPB 29/3/00   Moved 'csum' here from IP.C
** v0.13 JPB 11/4/00   Added buff_infile()
** v0.14 JPB 12/4/00   Added find_filesize();
** v0.15 JPB 3/7/00    Revised header for book CD
*/

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

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

#define CFGDELIMS " \t\r\n"         /* Config item delimiters */
#define MAXCFGLINE 90               /* Max length of line in CFG file */

BYTE bcast[MACLEN] = {BCASTADDR};   /* Broadcast MAC addr */
BYTE zermac[MACLEN];                /* All-zero MAC addr */
extern int netdebug;                /* Net packet display flags */

#if WIN32
long dir_handle=-1L;
struct _finddata_t dir_block;
#else
    struct ffblk dir_block;
#endif

/* Return maximum length of the given frame */
int getframe_maxlen(GENFRAME *gfp)
{
    return(gfp->g.dtype&DTYPE_ETHER ? MAXFRAME : MAXSLIP);
}

/* Return the Maximum Transmission Unit (i.e. data size) for the given frame */
WORD getframe_mtu(GENFRAME *gfp)
{
    WORD mtu;

    mtu = (WORD)getframe_maxlen(gfp);
    if (gfp->g.dtype & DTYPE_ETHER)
    {
        mtu -= sizeof(ETHERHDR);
        if (gfp->g.dtype & DTYPE_SNAP)
            mtu -= sizeof(SNAPHDR);
    }
    return(mtu);
}

/* Return frame header length, given driver type */
WORD dtype_hdrlen(WORD dtype)
{
    return(dtype&DTYPE_ETHER ? sizeof(ETHERHDR) : 0);
}

/* Get pointer to the data area of the given frame */
void *getframe_datap(GENFRAME *gfp)
{
    return(&gfp->buff[dtype_hdrlen(gfp->g.dtype)]);
}

/* Get pointer to the source address of the given frame, 0 if none */
BYTE *getframe_srcep(GENFRAME *gfp)
{
    ETHERHDR *ehp;
    BYTE *srce=0;

    if (gfp->g.dtype & DTYPE_ETHER)         /* Only Ethernet has address */
    {
        ehp = (ETHERHDR *)gfp->buff;
        srce = ehp->srce;
    }
    return(srce);
}

/* Copy the source MAC addr of the given frame; use broadcast if no addr */
BYTE *getframe_srce(GENFRAME *gfp, BYTE *buff)
{
    BYTE *p;

    p = getframe_srcep(gfp);
    if (p)
        memcpy(buff, p, MACLEN);
    else
        memcpy(buff, bcast, MACLEN);
    return(p);
}

/* Get pointer to the destination address of the given frame, 0 if none */
BYTE *getframe_destp(GENFRAME *gfp)
{
    ETHERHDR *ehp;
    BYTE *dest=0;

    if (gfp->g.dtype & DTYPE_ETHER)         /* Only Ethernet has address */
    {
        ehp = (ETHERHDR *)gfp->buff;
        dest = ehp->dest;
    }
    return(dest);
}

/* Copy the destination MAC addr of the given frame; use broadcast if no addr */
BYTE *getframe_dest(GENFRAME *gfp, BYTE *buff)
{
    BYTE *p;

    p = getframe_destp(gfp);
    if (p)
        memcpy(buff, p, MACLEN);
    else
        memcpy(buff, bcast, MACLEN);
    return(p);
}

/* Get the protocol for the given frame; if unknown , return 0 */
WORD getframe_pcol(GENFRAME *gfp)
{
    ETHERHDR *ehp;
    WORD pcol=0;

    if (gfp->g.dtype & DTYPE_ETHER)         /* Only Ethernet has protocol */
    {
        ehp = (ETHERHDR *)gfp->buff;
        pcol = ehp->ptype;
    }
    return(pcol);
}

/* Return non-zero if frame has a broadcast address */
int is_bcast(GENFRAME *gfp)
{
    return(gfp->g.dtype&DTYPE_ETHER && !memcmp(gfp->buff, bcast, MACLEN));
}

/* Check Ethernet frame, given frame pointer & length, return non-0 if OK */
int is_ether(GENFRAME *gfp, int len)
{
    int dlen=0;

    if (gfp && (gfp->g.dtype & DTYPE_ETHER) && len>=sizeof(ETHERHDR))
    {
        dlen = len - sizeof(ETHERHDR);
        swap_ether(gfp);
    }
    return(dlen);
}

/* Make a frame, given data length. Return length of complete frame
** If Ethernet, set dest addr & protocol type; if SLIP, ignore these */
int make_frame(GENFRAME *gfp, BYTE dest[], WORD pcol, WORD dlen)
{
    ETHERHDR *ehp;

    if (gfp->g.dtype & DTYPE_ETHER)
    {
        ehp = (ETHERHDR *)gfp->buff;
        ehp->ptype = pcol;
        memcpy(ehp->dest, dest, MACLEN);
        swap_ether(gfp);
        dlen += sizeof(ETHERHDR);
    }
    return(dlen);
}

/* Byte-swap an Ethernet frame, return header length */
void swap_ether(GENFRAME *gfp)
{
    ETHERFRAME *efp;

    efp = (ETHERFRAME *)gfp->buff;
    efp->h.ptype = swapw(efp->h.ptype);
}

/* Check SLIP frame, return non-zero if OK */
int is_slip(GENFRAME *gfp, int len)
{
    return((gfp->g.dtype & DTYPE_SLIP) && len>0);
}

/* Display SLIP or Ethernet frame (must be in network byte order) */
void disp_frame(GENFRAME *gfp, int dlen, int tx)
{
    char temps[20];
    BYTE *data, pcol;
    WORD type=0x0800;
    int i;

    printf(tx ? "Tx%u /" : "Rx%u \\", gfp->g.dtype & NETNUM_MASK);
    printf("len %u ", dlen);
    data = (BYTE *)getframe_datap(gfp);
    if (netdebug & 1)                       /* Verbose display? */
    {
        if (gfp->g.dtype & DTYPE_ETHER)
        {
            printf("%s ", ethstr(&gfp->buff[tx ? 0 : MACLEN], temps));
            type = swapw(*(WORD *)&gfp->buff[MACLEN*2]);
            if (type == 0x0806)
            {
                printf("ARP %s ", ipstr(swapl(*(long *)&data[14]), temps));
                printf("-> %s ", ipstr(swapl(*(long *)&data[24]), temps));
            }
        }
        else
            printf("------SLIP------- ");
        if (type == 0x0800)
        {
            printf("IP %s ", ipstr(swapl(*(long *)&data[12]), temps));
            printf("-> %s ", ipstr(swapl(*(long *)&data[16]), temps));
            pcol = *(data+9);
            printf(pcol==1 ? "ICMP" : pcol==6 ? "TCP" : pcol==17 ? "UDP" : "");
        }
        printf("\n");
    }
    if (netdebug & 2)                       /* Hex display? */
    {
        for (i=0; i<dlen; i++)
            printf(" %02X", data[i]);
        printf("\n");
    }
}

/* Convert IP address into a string */
char *ipstr(LWORD ip, char *s)
{
    sprintf(s, "%lu.%lu.%lu.%lu",(ip>>24)&255,(ip>>16)&255,(ip>>8)&255,ip&255);
    return(s);
}

/* Convert Ethernet address into a string (max 17 chars plus null) */
char *ethstr(BYTE *addr, char *str)
{
    int i;
    char *s=str;

    if (!memcmp(addr, bcast, MACLEN))
        strcpy(s, "----BROADCAST----");
    else for (i=0; i<MACLEN; i++)
        s += sprintf(s, i>0 ? ":%02x" : "%02x", *addr++);
    return(str);
}

/* Convert string to IP addr: first digits form most-significant byte  */
LWORD atoip(char *str)
{
    LWORD ip=0L;
    int i=4, n;
    char c=1;

    while (--i>=0 && c)
    {
        n = 0;
        while (isdigit(c=*str++))
            n = n*10 + c-'0';
        ip += (LWORD)n << (i*8);
    }
    return(ip);
}

/* Retrieve the integer value of a config item. Return 0 if not found */
int read_cfgval(char *fname, char *item, int *valp)
{
    char str[10];
    int ok=0;

    if ((ok = read_cfgstr(fname, item, str, sizeof(str)-1)) != 0)
    {
        if (valp)
            *valp = atoi(str);
    }
    return(ok);
}

/* Return the config string for the given item. Return 0 if not found */
int read_cfgstr(char *fname, char *item, char *dest, int destlen)
{
    return(read_cfgstr_n(fname, 0, item, dest, destlen));
}

/* Return the config string for the n'th item (1st item if n=0).
** Return 0 if not found */
int read_cfgstr_n(char *fname, int n, char *item, char *dest, int destlen)
{
    FILE *in;
    int ok=-1, len;
    char *s, buff[MAXCFGLINE];

    if ((in=fopen(fname, "rt")) != 0)       /* Open as text file */
    {                                       /* Read a line at a time */
        while (ok<n && fgets(buff, MAXCFGLINE, in))
        {
            strlwr(buff);                   /* Force to lower case */
            len = strcspn(buff, CFGDELIMS); /* Get length of config ID */
            if (len==(int)strlen(item) && !strncmp(buff, item, len))
            {                               /* If it matches my item.. */
                s = skipspace(&buff[len]);  /* ..skip whitespace.. */
                if (dest)
                {                           /* ..get length excl. EOL chars */
                    len = mini(strcspn(s, "\r\n"), destlen);
                    strncpy(dest, s, len);  /* Copy into destination */
                    dest[len] = 0;
                }
                ok++;
            }
        }
        fclose(in);
    }
    return(ok>=n);
}

/* Return non-zero if config item has option set (or 'all' options set) */
int read_cfgopt(char *fname, char *item, char *opt)
{
    char *s, buff[MAXCFGLINE];
    int n, ok=0;

    if (read_cfgstr(fname, item, buff, MAXCFGLINE-1))
    {
        s = buff;
        while (!ok && *s)
        {
            n = strcspn(s, CFGDELIMS);      /* Get length of next option */
            ok = !strncmp(s, opt, n) || !strncmp(s, "all", n);
            s = skippunct(s + n);           /* Match option, skip to next */
        }
    }
    return(ok);
}

/* Check the given token is at the start of the string
** Return pointer to the first char after the token, 0 if token not found */
char *skiptoken(char *str, char *tok)
{
    int n;
    char *s=0;

    n = strlen(tok);
    if (n>0 && str && !strnicmp(str, tok, n))
        s = str + n;
    return(s);