ppp.c

uCLinux下的一个TCP/IP协议栈源码

/*
 *  PPP.C	-- Send and receive datagrams on serial lines with
 *		   Point-to-Point Protocol
 *
 *	This implementation of PPP is declared to be in the public domain.
 *
 */

#include "global.h"
#include "mbuf.h"
#include "proc.h"
#include "iface.h"
#include "internet.h"
#include "ip.h"
#include "slhc.h"
#include "n8250.h"
#include "asy.h"
#include "pktdrvr.h"
#include "socket.h"
#include "devparam.h"
#include "ppp.h"
#include "pppfsm.h"
#include "ppplcp.h"
#include "ppppap.h"
#include "pppipcp.h"
#include "trace.h"

/* Routines local to this file */
static void htonppp(struct ppp_hdr *ppp, struct mbuf **data);

static void ppp_log(struct ppp_s *ppp_p, char *comment);
static void ppp_error(struct ppp_s *ppp_p, struct mbuf **bp, char *comment);
static void ppp_skipped(struct ppp_s *ppp_p, struct mbuf **bp, char *comment);

static int ppp_raw(struct iface *ifp, struct mbuf **data);

static void ppp_recv(int dev, void *p1, void *p2);

static int ppp_iostatus(struct iface *ifp, int command, int32 value);
static int ppp_discard(struct iface *ifp, struct mbuf **bpp);
static int ppp_echo(struct iface *ifp, struct mbuf **bpp);


/*
 * FCS lookup table as generated by fcsgen.c
 */
static uint16 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
};

#define pppfcs(fcs, c)		((fcs >> 8) ^ fcstab[(fcs ^ c) & 0x00ff])
#define SP_CHAR			0x20


/****************************************************************************/

/* Convert PPP header in host form to network form */
static void
htonppp(
struct ppp_hdr *ppp,
struct mbuf **bpp
){
	register uint8 *cp;

	/* Prepend header onto packet data */
	pushdown(bpp, NULL, PPP_HDR_LEN);

	/* Load header with proper values */
	cp = (*bpp)->data;
	*cp++ = ppp->addr;
	*cp++ = ppp->control;
	cp = put16(cp,ppp->protocol);
}


/************************************************************************/
/* General log routine */
static void
ppp_log( ppp_p, comment )
struct ppp_s *ppp_p;
char *comment;
{
	if (ppp_p->trace)
		trace_log(ppp_p->iface,"%s PPP %s",
			ppp_p->iface->name,
			comment);
}


/* Bad packet */
static void
ppp_error(ppp_p, bpp, comment)
struct ppp_s *ppp_p;
struct mbuf **bpp;
char *comment;
{
	free_p(bpp);
	ppp_log( ppp_p, comment );
}


/* Unknown type input packet */
static void
ppp_skipped(
struct ppp_s *ppp_p,
struct mbuf **bpp,
char *comment
){
	struct ipcp_s *ipcp_p;

	if ( (ipcp_p = ppp_p->fsm[IPcp].pdv) != NULL ) {
		slhc_toss( ipcp_p->slhcp );
	}
	ppp_error( ppp_p, bpp, comment );
}


/****************************************************************************/
/* Send IP datagram with Point-to-Point Protocol */
int
ppp_send(bpp,ifp,gateway,tos)
struct mbuf **bpp;	/* Buffer to send */
struct iface *ifp;	/* Pointer to interface control block */
int32 gateway;		/* Ignored (PPP is point-to-point) */
uint8 tos;
{
	struct ppp_s *ppp_p;
	struct ipcp_s *ipcp_p;
	int protocol = PPP_IP_PROTOCOL;

	if (ifp == NULL
	 || (ppp_p = ifp->edv) == NULL) {
		free_p(bpp);
		return -1;
	}

	if (ppp_p->fsm[IPcp].state != fsmOPENED) {
		ppp_error( ppp_p, bpp, "not open for IP traffic" );
		ppp_p->OutError++;
		return -1;
	}

	ipcp_p = ppp_p->fsm[IPcp].pdv;
	if (ipcp_p->remote.work.negotiate & IPCP_N_COMPRESS) {
		/* Attempt IP/TCP header compression */
		switch ( slhc_compress(ipcp_p->slhcp, bpp,
			ipcp_p->remote.work.slot_compress) ) {
		case SL_TYPE_IP:
			protocol = PPP_IP_PROTOCOL;
			break;
		case SL_TYPE_COMPRESSED_TCP:
			protocol = PPP_COMPR_PROTOCOL;
			break;
		case SL_TYPE_UNCOMPRESSED_TCP:
			protocol = PPP_UNCOMP_PROTOCOL;
			break;
		default:
			ppp_error( ppp_p, bpp, "bad IP packet" );
			ppp_p->OutError++;
			return -1;
		};
	}
	return (*ifp->output)(ifp,NULL,NULL,protocol,bpp);
}


/* Send a packet with PPP header */
int
ppp_output(
struct iface *ifp,	/* Pointer to interface control block */
char *dest,		/* Dest addr (ignored; PPP is point-to-point) */
char *source,		/* Source addr (ignored; PPP is point-to-point) */
uint16 protocol,		/* PPP Protocol Type field */
struct mbuf **data	/* Actual data to be sent */
){
	struct ppp_s *ppp_p;
	struct ppp_hdr hdr;

	if (ifp == NULL
	 || (ppp_p = ifp->edv) == NULL) {
		free_p(data);
		return -1;
	}

	if (ppp_p->phase == pppDEAD) {
		ppp_error( ppp_p, data, "line not up" );
		ppp_p->OutError++;
		return -1;
	}

	hdr.addr = HDLC_ALL_ADDR;
	hdr.control = HDLC_UI;
	hdr.protocol = protocol;

	htonppp(&hdr, data);
	return (*ifp->raw)(ifp,data);
}


/* Encode a raw packet in PPP framing, put on link output queue */
static int
ppp_raw(
struct iface *ifp,
struct mbuf **bpp
){
	struct ppp_s *ppp_p = ifp->edv;
	struct lcp_s *lcp_p = ppp_p->fsm[Lcp].pdv;
	int full_lcp, full_ac, full_p;
	uint16 calc_fcs = HDLC_FCS_START;
	int32 accm = LCP_ACCM_DEFAULT;
	struct ppp_hdr ph;
	int len = PPP_HDR_LEN;
	struct mbuf *vbp;
	register uint8 *cp;
	register int c;

	dump(ifp,IF_TRACE_OUT,*bpp);
	ppp_p->OutTxOctetCount += len_p(*bpp) + 2;  /* count FCS bytes */
	ifp->rawsndcnt++;
	ifp->lastsent = secclock();

	/* Get the HDLC/PPP header, without actually pulling mbuf up */
	if ( *bpp == NULL || (*bpp)->cnt < PPP_HDR_LEN ) {
		ppp_error( ppp_p, bpp, "link header missing" );
		ppp_p->OutError++;
		return -1;
	}

	ph.addr = (*bpp)->data[0];
	ph.control = (*bpp)->data[1];
	ph.protocol = get16(&(*bpp)->data[2]);

	if ( ( full_lcp = (ph.protocol == PPP_LCP_PROTOCOL) ) == 0
	 && (lcp_p->remote.work.negotiate & LCP_N_ACCM) ) {
		accm = lcp_p->remote.work.accm;
	}

	if ( ( full_p = ( full_lcp
			||  !(lcp_p->remote.work.negotiate & LCP_N_PFC)
			||  ph.protocol >= 0x00ff ) )
	    == 0 ) {
		--len;
	}

	/* Discard HDLC address and control fields if possible */
	if ( ( full_ac = ( full_lcp
			||  !(lcp_p->remote.work.negotiate & LCP_N_ACFC) ) )
	    == 0 ) {
		len -= 2;
	}

	/* Load header with proper values */
	(*bpp)->cnt -= PPP_HDR_LEN - len;
	cp = ((*bpp)->data += PPP_HDR_LEN - len);

	if ( full_ac ) {
		*cp++ = ph.addr;
		*cp++ = ph.control;
	}
	if ( full_p )
		*cp++ = (ph.protocol >> 8);
	*cp++ = (ph.protocol & 0x00ff);

	/* Allocate output mbuf that's twice as long as the packet.
	 * This is a worst-case guess (consider a packet full of HDLC_FLAGs!)
	 */
	if ((vbp = alloc_mbuf((uint16)(2*len_p(*bpp) + HDLC_ENVLEN))) == NULL) {
		ppp_error( ppp_p, bpp, Nospace );
		ppp_p->OutMemory++;
		return -1;
	}
	cp = vbp->data;

	/* No need to send an opening flag if the previous packet is still
	 * being transmitted.
	 */
	if ( Asy[ifp->dev].dma.busy == 0 ) {
		/* Flush out any line garbage */
		*cp++ = HDLC_FLAG;
		ppp_p->OutOpenFlag++;
	}

	/* Copy input to output, escaping special characters */
	while ((c = PULLCHAR(bpp)) != -1) {
		/* Fold char value into FCS calculated so far */
		calc_fcs = pppfcs(calc_fcs, c);

		if ( ((c < SP_CHAR) && (accm & (1L << c)))
		    || (c == HDLC_ESC_ASYNC)
		    || (c == HDLC_FLAG)) {
			*cp++ = HDLC_ESC_ASYNC;
			*cp++ = (c ^ HDLC_ESC_COMPL);
		} else {
			*cp++ = c;
		}
	}

	/* Final FCS calculation */
	calc_fcs ^= 0xffff;
	c = (calc_fcs & 0x00ff);	/* Least significant byte first */
	if ( ((c < SP_CHAR) && (accm & (1L << c)))
	     ||(c == HDLC_ESC_ASYNC)
	     ||(c == HDLC_FLAG)) {
		*cp++ = HDLC_ESC_ASYNC;
		*cp++ = (c ^ HDLC_ESC_COMPL);
	} else {
		*cp++ = c;
	}
	c = (calc_fcs >> 8);		/* Most significant byte next */
	if ( ((c < SP_CHAR) && (accm & (1L << c)))
	     ||(c == HDLC_ESC_ASYNC)
	     ||(c == HDLC_FLAG)) {
		*cp++ = HDLC_ESC_ASYNC;
		*cp++ = (c ^ HDLC_ESC_COMPL);
	} else {
		*cp++ = c;
	}

	/* Tie off the packet */
	*cp++ = HDLC_FLAG;
	vbp->cnt = cp - vbp->data;

	if (ifp->trace & IF_TRACE_RAW)
		raw_dump(ifp,IF_TRACE_OUT,vbp);
	return asy_send(ifp->dev,&vbp);
}


/****************************************************************************/
/* Packetize PPP input from device */
/* (process started by ppp_init) */
void
ppp_recv(dev,p1,p2)
int dev;
void *p1;
void *p2;
{
	struct iface *ifp = p1;
	struct ppp_s *ppp_p = ifp->edv;
	int32 accm = LCP_ACCM_DEFAULT;
	uint16 calc_fcs = HDLC_FCS_START;
	struct mbuf *raw_bp = NULL;
	struct mbuf *head_bp = NULL;
	struct mbuf *tail_bp = NULL;
	uint8 *cp;			/* next byte in tail mbuf */
	register int mode = FALSE;
	register int c;

	while ( (c = get_asy(dev)) != -1 ) {
#ifdef PPP_DEBUG_RAW
		if (ifp->trace & IF_TRACE_RAW) {
			if ( raw_bp != NULL
			  || (raw_bp = alloc_mbuf( LCP_MRU_HI * 2 )) != NULL ) {
				*raw_bp->data++ = c;
				raw_bp->cnt++;
				if ( raw_bp->cnt != 1 && c == HDLC_FLAG ) {
					raw_bp->data = (uint8 *)(raw_bp + 1);
					raw_dump( ifp, IF_TRACE_IN, raw_bp );
					raw_bp->cnt = 0;
				}
			}
		}
#endif
		if ( c == HDLC_FLAG ) {