#if HAVE_CONFIG_H
#include <config.h>
#endif

#include "pptpd.h"
#include <utmp.h>
#include <sys/time.h>

static u_int16_t fcstab[];

int old_ttyalloc( int *in, int *out, int *io, char *name )
{ char ttyname[16];
  int i,j,fp,ft;
        strcpy(ttyname,"/dev/ptyXX");
        for(i=0;(ttyname[8]="pqrstuvwxyzabcde"[i]);i++)
          for(j=0;(ttyname[9]="0123456789abcdef"[j]);j++)
        {  if( (fp=open(ttyname,O_RDWR))>=0 )
           {    ttyname[5]='t';
                ft=access(ttyname,R_OK|W_OK);
                if( io!=NULL && ft>=0 )
                        ft=*io=open(ttyname,O_RDWR);
                if( in!=NULL && ft>=0 )
                        ft=*in=open(ttyname,O_RDONLY);
                if( out!=NULL && ft>=0 )
                        ft=*out=open(ttyname,O_WRONLY);
                if( ft>=0 )
                {       if( name!=NULL )
                                strcpy(name,ttyname);
                        return(fp);
                }
                if( in!=NULL && *in>=0 )        close(*in);
                if( out!=NULL && *out>=0 )      close(*out);
                if( io!=NULL && *io>=0 )        close(*io);
                close(fp);
                ttyname[5]='p';
           }
        }
        return(-1);
}

struct aval_ppp *conf_ppp_cmdlines=NULL;
struct aval_ppp *conf_ppp_cmdlines_last=NULL;

int conf_ppp( char *filename )
{ FILE *f;
  int n=0;
  int line = 0;
  struct aval_ppp *cp;
  char buf[256], *p;
	if( (f=fopen(filename,"r"))==NULL )
		return(-1);
	while( fgets(buf,sizeof(buf),f)!=NULL )
	{
		line++;
		for (p=buf; *p; p++)
			if (!isspace(*p))
				break;
		if( buf[strlen(buf)-1]=='\n' )
			buf[strlen(buf)-1]=0;

		if( *p==0 || *p=='#')
			continue;

		if( (cp=malloc(sizeof(struct aval_ppp)+strlen(p)+1))==NULL )
		{	LOG("Out of memory\n");
		}
		else
		{	cp->next=NULL;
			cp->index = line;
			strcpy(cp->line,p);
			if( conf_ppp_cmdlines==NULL )
			{	conf_ppp_cmdlines=cp;
				conf_ppp_cmdlines_last=cp;
			}
			else	{
				conf_ppp_cmdlines_last->next=cp;
				conf_ppp_cmdlines_last=cp;
			}
			n++;
		}
	}
	fclose(f);
	return(n);
}

int run_ppp( struct ppp_struct *p )
{ int pty;
  pid_t pid;
  char fn[128];
  struct utmp ut;

	if( (pty=old_ttyalloc(NULL,NULL,NULL,fn))<0 )
		return(-1);
	switch( (pid=fork()) )
	{	case 0:
			LOG("starting pppd with pid %d", getpid());
			close(pty);
			close(0);
			close(1);
			close(2);
			setsid();
			open(fn,O_RDONLY);
			open(fn,O_WRONLY);
			open(fn,O_WRONLY);
			{ char * q = strdup(p->cmdline->line);
			  char *av[128];
			  char buf[128];
			  int a=0;
			  int i;
			
			  if (!q) {
				  LOG("not enough memory");
				  exit(-1);
			  }
			for (i=3; i<256; i++)
				close(i);
			  av[a++]=PPPD_BINARY;
			  av[a++]="file";
			  av[a++]=PPPD_CFG;
			  sprintf (buf, "PPTP:%d", p->cmdline->index);
			  setenv("CALLER_ID", "none", 0);
			  setenv("CONNECT", buf, 1);
			memset(&ut, 0, sizeof(ut));
			ut.ut_type = LOGIN_PROCESS;
			ut.ut_pid = getpid();
			if (!strncmp(fn, "/dev/", 5))
				strncpy(ut.ut_line, fn+5, UT_LINESIZE);
			else
				strncpy(ut.ut_line, fn, UT_LINESIZE);
			strncpy(ut.ut_host, buf, UT_HOSTSIZE);
			gettimeofday(&(ut.ut_tv), NULL);

			setutent();
			pututline(&ut);
			endutent();

			  while( *q!=0 && a<126 )
			  {	while( *q==' ' || *q=='\t' )	q++;
			  	av[a++]=q;
			  	while( *q!=0 && *q!=' ' && *q!='\t' ) q++;
				if( *q!=0 )	*q++=0;
			  }
			  av[a++]=NULL;
			  execvp(av[0],av);
			}
			exit(0);
		case -1:
			close(pty);
			return(-1);
		default:
			p->ppp_pid = pid;
	}
	return(pty);
}

struct ppp_struct *new_ppp( struct control_struct *c )
{ struct ppp_struct *p,*n;
	if( (n=malloc(sizeof(struct ppp_struct)))==NULL )
		return(NULL);
	memset(n, 0, sizeof(struct ppp_struct));
	n->call_id=1;
	for(p=c->ppp;p!=NULL; p = p->next)
		if( n->call_id==p->call_id )
		{	n->call_id++;
			p=c->ppp;
			continue;
		}
	if( conf_ppp_cmdlines==NULL )
	{	free(n);
		LOG("out of cmdlines");
		return(NULL);
	}
	n->cmdline=conf_ppp_cmdlines;
	conf_ppp_cmdlines=conf_ppp_cmdlines->next;
	n->cmdline->next=NULL;
	if( (n->fd= run_ppp(n))<0 )
	{	n->cmdline->next=conf_ppp_cmdlines;
		conf_ppp_cmdlines=n->cmdline->next;
		free(n);
		return(NULL);
	}
	n->fcs16 = n->buf_pos = 0;
	n->buf_flags = PPP_NOISE_TO_FLAG;
	n->next=c->ppp; c->ppp=n;
	return(n);
}

void release_ppp( struct ppp_struct *p )
{
	struct utmp * ut, lut;

	if( p->fd>=0 )	close(p->fd);
	if( p->cmdline!=NULL )
	{	p->cmdline->next=conf_ppp_cmdlines;
		conf_ppp_cmdlines=p->cmdline;
	}

	setutent();
	while ((ut=getutent())) if (ut->ut_pid == p->ppp_pid) {
		memcpy(&lut, ut, sizeof(lut));
		lut.ut_type = DEAD_PROCESS;
		pututline(&lut);
	}
	endutent();

	free(p);
}

void unlink_and_release_ppp(struct ppp_struct *** pp, u_int16_t call_id)
{
	struct ppp_struct * p;

	while (**pp!=NULL) {
		if ((**pp)->peers_call_id == call_id) {
			p=**pp;
			**pp=(**pp)->next;
			release_ppp(p);
			return;
		}

		if ((**pp)->next == NULL)
			break;
		*pp=&((**pp)->next);
	}
}

#define NEED_ESCAPE(X) (((unsigned char)(X)) < 0x20 || (X)==HDLC_ESCAPE || (X)==HDLC_FLAG)

int send_ppp_packet(struct control_struct * ctrl, struct ppp_struct * ppp, char * in, int in_len)
{
	char buf[2*PPPFRAME_MAX];
	int i = 0;
	u_int16_t fcs16 = PPPINITFCS16;

	buf[i++] = HDLC_FLAG;
	for (;in_len; in_len--) {
		fcs16 = (fcs16 >> 8) ^ fcstab[(fcs16 ^ *in) & 0xff];
		if (NEED_ESCAPE(*in)) {
			buf[i++] = HDLC_ESCAPE;
			*in ^= 0x20;
		}
		buf[i++] = *in++;
		if (i>sizeof(buf)-2) {
			LOG("refusing to send over-sized packet (%d bytes long)", in_len);
			return -1;
		}
	}
	fcs16 ^= 0xffff;
	if (NEED_ESCAPE(fcs16&0xff)) {
		buf[i++] = HDLC_ESCAPE;
		fcs16 ^= 0x20;
	}
	buf[i++] = fcs16 & 0xff;
	if (NEED_ESCAPE(fcs16>>8)) {
		buf[i++] = HDLC_ESCAPE;
		fcs16 ^= 0x20 << 8;
	}
	buf[i++] = fcs16 >> 8;

	buf[i++] = HDLC_FLAG;
	write(ppp->fd, buf, i);

	return 0;
}

int read_ppp_packet(struct control_struct * ctrl, struct ppp_struct * ppp)
{
	int i;
	char buf[2*PPPFRAME_MAX], * p;
	
	i = read(ppp->fd, buf, sizeof(buf));
	if (i<=0) {
		LOG("cannot read from pppd (remote end died?)");
		return -1;
	}
	for (p=buf; p<buf+i; p++)
	if ((ppp->buf_flags != PPP_NOISE_TO_FLAG) || (*p == HDLC_FLAG)) /* silently discard initial noise on line */
	switch (*p) { /* and take care of rest bytes */
		case HDLC_FLAG:
			if (ppp->buf_pos < 4 || (ppp->buf_flags & PPP_BUF_ESCAPE)) {
				ppp->buf_flags = 0;
				ppp->buf_pos = 0;
				ppp->fcs16 = PPPINITFCS16;
				break;
			}
			if (ppp->fcs16 != PPPGOODFCS16) {
				LOG("discarding PPP frame with bad FCS (0x%.4f instead of 0x%.4f", ppp->fcs16, PPPGOODFCS16);
				ppp->buf_flags = 0;
				ppp->buf_pos = 0;
				ppp->fcs16 = PPPINITFCS16;
				break;
			} else
				ppp->buf_pos -= 2; /* strip FCS, as it is link-speciffic */
			send_gre_packet(ctrl, ppp, ppp->buf, ppp->buf_pos);
			ppp->buf_flags = 0;
			ppp->buf_pos = 0;
			ppp->fcs16 = PPPINITFCS16;
			break;
		case HDLC_ESCAPE:
			ppp->buf_flags |= PPP_BUF_ESCAPE;
			break;
		default:
			if (ppp->buf_flags & PPP_BUF_ESCAPE) {
				*p ^= 0x20;
				ppp->buf_flags &= ~PPP_BUF_ESCAPE;
			}
			ppp->buf[ppp->buf_pos++] = *p;
			ppp->fcs16 = (ppp->fcs16 >> 8) ^ fcstab[(ppp->fcs16 ^ *p) & 0xff];
			if (ppp->buf_pos == sizeof(ppp->buf)) {
				ppp->buf_flags = PPP_NOISE_TO_FLAG;
				ppp->buf_pos = 0;
			}
			break;
	}

	return 0;
}

static u_int16_t fcstab[256] = {
	0x0000, 0x1189, 0x2312, 0x329b, 0x4624, 0x57ad, 0x6536, 0x74bf,
	0x8c48, 0x9dc1, 0xaf5a, 0xbed3, 0xca6c, 0xdbe5, 0xe97e, 0xf8f7,
	0x1081, 0x0108, 0x3393, 0x221a, 0x56a5, 0x472c, 0x75b7, 0x643e,
	0x9cc9, 0x8d40, 0xbfdb, 0xae52, 0xdaed, 0xcb64, 0xf9ff, 0xe876,
	0x2102, 0x308b, 0x0210, 0x1399, 0x6726, 0x76af, 0x4434, 0x55bd,
	0xad4a, 0xbcc3, 0x8e58, 0x9fd1, 0xeb6e, 0xfae7, 0xc87c, 0xd9f5,
	0x3183, 0x200a, 0x1291, 0x0318, 0x77a7, 0x662e, 0x54b5, 0x453c,
	0xbdcb, 0xac42, 0x9ed9, 0x8f50, 0xfbef, 0xea66, 0xd8fd, 0xc974,
	0x4204, 0x538d, 0x6116, 0x709f, 0x0420, 0x15a9, 0x2732, 0x36bb,
	0xce4c, 0xdfc5, 0xed5e, 0xfcd7, 0x8868, 0x99e1, 0xab7a, 0xbaf3,
	0x5285, 0x430c, 0x7197, 0x601e, 0x14a1, 0x0528, 0x37b3, 0x263a,
	0xdecd, 0xcf44, 0xfddf, 0xec56, 0x98e9, 0x8960, 0xbbfb, 0xaa72,
	0x6306, 0x728f, 0x4014, 0x519d, 0x2522, 0x34ab, 0x0630, 0x17b9,
	0xef4e, 0xfec7, 0xcc5c, 0xddd5, 0xa96a, 0xb8e3, 0x8a78, 0x9bf1,
	0x7387, 0x620e, 0x5095, 0x411c, 0x35a3, 0x242a, 0x16b1, 0x0738,
	0xffcf, 0xee46, 0xdcdd, 0xcd54, 0xb9eb, 0xa862, 0x9af9, 0x8b70,
	0x8408, 0x9581, 0xa71a, 0xb693, 0xc22c, 0xd3a5, 0xe13e, 0xf0b7,
	0x0840, 0x19c9, 0x2b52, 0x3adb, 0x4e64, 0x5fed, 0x6d76, 0x7cff,
	0x9489, 0x8500, 0xb79b, 0xa612, 0xd2ad, 0xc324, 0xf1bf, 0xe036,
	0x18c1, 0x0948, 0x3bd3, 0x2a5a, 0x5ee5, 0x4f6c, 0x7df7, 0x6c7e,
	0xa50a, 0xb483, 0x8618, 0x9791, 0xe32e, 0xf2a7, 0xc03c, 0xd1b5,
	0x2942, 0x38cb, 0x0a50, 0x1bd9, 0x6f66, 0x7eef, 0x4c74, 0x5dfd,
	0xb58b, 0xa402, 0x9699, 0x8710, 0xf3af, 0xe226, 0xd0bd, 0xc134,
	0x39c3, 0x284a, 0x1ad1, 0x0b58, 0x7fe7, 0x6e6e, 0x5cf5, 0x4d7c,
	0xc60c, 0xd785, 0xe51e, 0xf497, 0x8028, 0x91a1, 0xa33a, 0xb2b3,
	0x4a44, 0x5bcd, 0x6956, 0x78df, 0x0c60, 0x1de9, 0x2f72, 0x3efb,
	0xd68d, 0xc704, 0xf59f, 0xe416, 0x90a9, 0x8120, 0xb3bb, 0xa232,
	0x5ac5, 0x4b4c, 0x79d7, 0x685e, 0x1ce1, 0x0d68, 0x3ff3, 0x2e7a,
	0xe70e, 0xf687, 0xc41c, 0xd595, 0xa12a, 0xb0a3, 0x8238, 0x93b1,
	0x6b46, 0x7acf, 0x4854, 0x59dd, 0x2d62, 0x3ceb, 0x0e70, 0x1ff9,
	0xf78f, 0xe606, 0xd49d, 0xc514, 0xb1ab, 0xa022, 0x92b9, 0x8330,
	0x7bc7, 0x6a4e, 0x58d5, 0x495c, 0x3de3, 0x2c6a, 0x1ef1, 0x0f78 
};