net/x25/x25_facilities.c - linux - Git at Google

 /*
  *	X.25 Packet Layer release 002
  *
  *	This is ALPHA test software. This code may break your machine,
  *	randomly fail to work with new releases, misbehave and/or generally
  *	screw up. It might even work.
  *
  *	This code REQUIRES 2.1.15 or higher
  *
  *	This module:
  *		This module is free software; you can redistribute it and/or
  *		modify it under the terms of the GNU General Public License
  *		as published by the Free Software Foundation; either version
  *		2 of the License, or (at your option) any later version.
  *
  *	History
  *	X.25 001	Split from x25_subr.c
  *	mar/20/00	Daniela Squassoni Disabling/enabling of facilities
  *					  negotiation.
  *	apr/14/05	Shaun Pereira - Allow fast select with no restriction
  *					on response.
  */

 #define pr_fmt(fmt) "X25: " fmt

 #include <linux/kernel.h>
 #include <linux/string.h>
 #include <linux/skbuff.h>
 #include <net/sock.h>
 #include <net/x25.h>

 /**
  * x25_parse_facilities - Parse facilities from skb into the facilities structs
  *
  * @skb: sk_buff to parse
  * @facilities: Regular facilities, updated as facilities are found
  * @dte_facs: ITU DTE facilities, updated as DTE facilities are found
  * @vc_fac_mask: mask is updated with all facilities found
  *
  * Return codes:
  *  -1 - Parsing error, caller should drop call and clean up
  *   0 - Parse OK, this skb has no facilities
  *  >0 - Parse OK, returns the length of the facilities header
  *
  */
 int x25_parse_facilities(struct sk_buff *skb, struct x25_facilities *facilities,
 		struct x25_dte_facilities *dte_facs, unsigned long *vc_fac_mask)
 {
 	unsigned char *p;
 	unsigned int len;

 	*vc_fac_mask = 0;

 	/*
 	 * The kernel knows which facilities were set on an incoming call but
 	 * currently this information is not available to userspace.  Here we
 	 * give userspace who read incoming call facilities 0 length to indicate
 	 * it wasn't set.
 	 */
 	dte_facs->calling_len = 0;
 	dte_facs->called_len = 0;
 	memset(dte_facs->called_ae, '\0', sizeof(dte_facs->called_ae));
 	memset(dte_facs->calling_ae, '\0', sizeof(dte_facs->calling_ae));

 	if (!pskb_may_pull(skb, 1))
 		return 0;

 	len = skb->data[0];

 	if (!pskb_may_pull(skb, 1 + len))
 		return -1;

 	p = skb->data + 1;

 	while (len > 0) {
 		switch (*p & X25_FAC_CLASS_MASK) {
 		case X25_FAC_CLASS_A:
 			if (len < 2)
 				return -1;
 			switch (*p) {
 			case X25_FAC_REVERSE:
 				if((p[1] & 0x81) == 0x81) {
 					facilities->reverse = p[1] & 0x81;
 					*vc_fac_mask |= X25_MASK_REVERSE;
 					break;
 				}

 				if((p[1] & 0x01) == 0x01) {
 					facilities->reverse = p[1] & 0x01;
 					*vc_fac_mask |= X25_MASK_REVERSE;
 					break;
 				}

 				if((p[1] & 0x80) == 0x80) {
 					facilities->reverse = p[1] & 0x80;
 					*vc_fac_mask |= X25_MASK_REVERSE;
 					break;
 				}

 				if(p[1] == 0x00) {
 					facilities->reverse
 						= X25_DEFAULT_REVERSE;
 					*vc_fac_mask |= X25_MASK_REVERSE;
 					break;
 				}

 			case X25_FAC_THROUGHPUT:
 				facilities->throughput = p[1];
 				*vc_fac_mask |= X25_MASK_THROUGHPUT;
 				break;
 			case X25_MARKER:
 				break;
 			default:
 				pr_debug("unknown facility "
 				       "%02X, value %02X\n",
 				       p[0], p[1]);
 				break;
 			}
 			p   += 2;
 			len -= 2;
 			break;
 		case X25_FAC_CLASS_B:
 			if (len < 3)
 				return -1;
 			switch (*p) {
 			case X25_FAC_PACKET_SIZE:
 				facilities->pacsize_in  = p[1];
 				facilities->pacsize_out = p[2];
 				*vc_fac_mask |= X25_MASK_PACKET_SIZE;
 				break;
 			case X25_FAC_WINDOW_SIZE:
 				facilities->winsize_in  = p[1];
 				facilities->winsize_out = p[2];
 				*vc_fac_mask |= X25_MASK_WINDOW_SIZE;
 				break;
 			default:
 				pr_debug("unknown facility "
 				       "%02X, values %02X, %02X\n",
 				       p[0], p[1], p[2]);
 				break;
 			}
 			p   += 3;
 			len -= 3;
 			break;
 		case X25_FAC_CLASS_C:
 			if (len < 4)
 				return -1;
 			pr_debug("unknown facility %02X, "
 			       "values %02X, %02X, %02X\n",
 			       p[0], p[1], p[2], p[3]);
 			p   += 4;
 			len -= 4;
 			break;
 		case X25_FAC_CLASS_D:
 			if (len < p[1] + 2)
 				return -1;
 			switch (*p) {
 			case X25_FAC_CALLING_AE:
 				if (p[1] > X25_MAX_DTE_FACIL_LEN || p[1] <= 1)
 					return -1;
 				if (p[2] > X25_MAX_AE_LEN)
 					return -1;
 				dte_facs->calling_len = p[2];
 				memcpy(dte_facs->calling_ae, &p[3], p[1] - 1);
 				*vc_fac_mask |= X25_MASK_CALLING_AE;
 				break;
 			case X25_FAC_CALLED_AE:
 				if (p[1] > X25_MAX_DTE_FACIL_LEN || p[1] <= 1)
 					return -1;
 				if (p[2] > X25_MAX_AE_LEN)
 					return -1;
 				dte_facs->called_len = p[2];
 				memcpy(dte_facs->called_ae, &p[3], p[1] - 1);
 				*vc_fac_mask |= X25_MASK_CALLED_AE;
 				break;
 			default:
 				pr_debug("unknown facility %02X,"
 					"length %d\n", p[0], p[1]);
 				break;
 			}
 			len -= p[1] + 2;
 			p += p[1] + 2;
 			break;
 		}
 	}

 	return p - skb->data;
 }

 /*
  *	Create a set of facilities.
  */
 int x25_create_facilities(unsigned char *buffer,
 		struct x25_facilities *facilities,
 		struct x25_dte_facilities *dte_facs, unsigned long facil_mask)
 {
 	unsigned char *p = buffer + 1;
 	int len;

 	if (!facil_mask) {
 		/*
 		 * Length of the facilities field in call_req or
 		 * call_accept packets
 		 */
 		buffer[0] = 0;
 		len = 1; /* 1 byte for the length field */
 		return len;
 	}

 	if (facilities->reverse && (facil_mask & X25_MASK_REVERSE)) {
 		*p++ = X25_FAC_REVERSE;
 		*p++ = facilities->reverse;
 	}

 	if (facilities->throughput && (facil_mask & X25_MASK_THROUGHPUT)) {
 		*p++ = X25_FAC_THROUGHPUT;
 		*p++ = facilities->throughput;
 	}

 	if ((facilities->pacsize_in || facilities->pacsize_out) &&
 	    (facil_mask & X25_MASK_PACKET_SIZE)) {
 		*p++ = X25_FAC_PACKET_SIZE;
 		*p++ = facilities->pacsize_in ? : facilities->pacsize_out;
 		*p++ = facilities->pacsize_out ? : facilities->pacsize_in;
 	}

 	if ((facilities->winsize_in || facilities->winsize_out) &&
 	    (facil_mask & X25_MASK_WINDOW_SIZE)) {
 		*p++ = X25_FAC_WINDOW_SIZE;
 		*p++ = facilities->winsize_in ? : facilities->winsize_out;
 		*p++ = facilities->winsize_out ? : facilities->winsize_in;
 	}

 	if (facil_mask & (X25_MASK_CALLING_AE|X25_MASK_CALLED_AE)) {
 		*p++ = X25_MARKER;
 		*p++ = X25_DTE_SERVICES;
 	}

 	if (dte_facs->calling_len && (facil_mask & X25_MASK_CALLING_AE)) {
 		unsigned int bytecount = (dte_facs->calling_len + 1) >> 1;
 		*p++ = X25_FAC_CALLING_AE;
 		*p++ = 1 + bytecount;
 		*p++ = dte_facs->calling_len;
 		memcpy(p, dte_facs->calling_ae, bytecount);
 		p += bytecount;
 	}

 	if (dte_facs->called_len && (facil_mask & X25_MASK_CALLED_AE)) {
 		unsigned int bytecount = (dte_facs->called_len % 2) ?
 		dte_facs->called_len / 2 + 1 :
 		dte_facs->called_len / 2;
 		*p++ = X25_FAC_CALLED_AE;
 		*p++ = 1 + bytecount;
 		*p++ = dte_facs->called_len;
 		memcpy(p, dte_facs->called_ae, bytecount);
 		p+=bytecount;
 	}

 	len       = p - buffer;
 	buffer[0] = len - 1;

 	return len;
 }

 /*
  *	Try to reach a compromise on a set of facilities.
  *
  *	The only real problem is with reverse charging.
  */
 int x25_negotiate_facilities(struct sk_buff *skb, struct sock *sk,
 		struct x25_facilities *new, struct x25_dte_facilities *dte)
 {
 	struct x25_sock *x25 = x25_sk(sk);
 	struct x25_facilities *ours = &x25->facilities;
 	struct x25_facilities theirs;
 	int len;

 	memset(&theirs, 0, sizeof(theirs));
 	memcpy(new, ours, sizeof(*new));
 	memset(dte, 0, sizeof(*dte));

 	len = x25_parse_facilities(skb, &theirs, dte, &x25->vc_facil_mask);
 	if (len < 0)
 		return len;

 	/*
 	 *	They want reverse charging, we won't accept it.
 	 */
 	if ((theirs.reverse & 0x01 ) && (ours->reverse & 0x01)) {
 		SOCK_DEBUG(sk, "X.25: rejecting reverse charging request\n");
 		return -1;
 	}

 	new->reverse = theirs.reverse;

 	if (theirs.throughput) {
 		int theirs_in =  theirs.throughput & 0x0f;
 		int theirs_out = theirs.throughput & 0xf0;
 		int ours_in  = ours->throughput & 0x0f;
 		int ours_out = ours->throughput & 0xf0;
 		if (!ours_in || theirs_in < ours_in) {
 			SOCK_DEBUG(sk, "X.25: inbound throughput negotiated\n");
 			new->throughput = (new->throughput & 0xf0) | theirs_in;
 		}
 		if (!ours_out || theirs_out < ours_out) {
 			SOCK_DEBUG(sk,
 				"X.25: outbound throughput negotiated\n");
 			new->throughput = (new->throughput & 0x0f) | theirs_out;
 		}
 	}

 	if (theirs.pacsize_in && theirs.pacsize_out) {
 		if (theirs.pacsize_in < ours->pacsize_in) {
 			SOCK_DEBUG(sk, "X.25: packet size inwards negotiated down\n");
 			new->pacsize_in = theirs.pacsize_in;
 		}
 		if (theirs.pacsize_out < ours->pacsize_out) {
 			SOCK_DEBUG(sk, "X.25: packet size outwards negotiated down\n");
 			new->pacsize_out = theirs.pacsize_out;
 		}
 	}

 	if (theirs.winsize_in && theirs.winsize_out) {
 		if (theirs.winsize_in < ours->winsize_in) {
 			SOCK_DEBUG(sk, "X.25: window size inwards negotiated down\n");
 			new->winsize_in = theirs.winsize_in;
 		}
 		if (theirs.winsize_out < ours->winsize_out) {
 			SOCK_DEBUG(sk, "X.25: window size outwards negotiated down\n");
 			new->winsize_out = theirs.winsize_out;
 		}
 	}

 	return len;
 }

 /*
  *	Limit values of certain facilities according to the capability of the
  *      currently attached x25 link.
  */
 void x25_limit_facilities(struct x25_facilities *facilities,
 			  struct x25_neigh *nb)
 {

 	if (!nb->extended) {
 		if (facilities->winsize_in  > 7) {
 			pr_debug("incoming winsize limited to 7\n");
 			facilities->winsize_in = 7;
 		}
 		if (facilities->winsize_out > 7) {
 			facilities->winsize_out = 7;
 			pr_debug("outgoing winsize limited to 7\n");
 		}
 	}
 }
	/*
	* X.25 Packet Layer release 002
	*
	* This is ALPHA test software. This code may break your machine,
	* randomly fail to work with new releases, misbehave and/or generally
	* screw up. It might even work.
	*
	* This code REQUIRES 2.1.15 or higher
	*
	* This module:
	* This module is free software; you can redistribute it and/or
	* modify it under the terms of the GNU General Public License
	* as published by the Free Software Foundation; either version
	* 2 of the License, or (at your option) any later version.
	*
	* History
	* X.25 001 Split from x25_subr.c
	* mar/20/00 Daniela Squassoni Disabling/enabling of facilities
	* negotiation.
	* apr/14/05 Shaun Pereira - Allow fast select with no restriction
	* on response.
	*/

	#define pr_fmt(fmt) "X25: " fmt

	#include <linux/kernel.h>
	#include <linux/string.h>
	#include <linux/skbuff.h>
	#include <net/sock.h>
	#include <net/x25.h>

	/**
	* x25_parse_facilities - Parse facilities from skb into the facilities structs
	*
	* @skb: sk_buff to parse
	* @facilities: Regular facilities, updated as facilities are found
	* @dte_facs: ITU DTE facilities, updated as DTE facilities are found
	* @vc_fac_mask: mask is updated with all facilities found
	*
	* Return codes:
	* -1 - Parsing error, caller should drop call and clean up
	* 0 - Parse OK, this skb has no facilities
	* >0 - Parse OK, returns the length of the facilities header
	*
	*/
	int x25_parse_facilities(struct sk_buff skb, struct x25_facilities facilities,
	struct x25_dte_facilities dte_facs, unsigned long vc_fac_mask)
	{
	unsigned char *p;
	unsigned int len;

	*vc_fac_mask = 0;

	/*
	* The kernel knows which facilities were set on an incoming call but
	* currently this information is not available to userspace. Here we
	* give userspace who read incoming call facilities 0 length to indicate
	* it wasn't set.
	*/
	dte_facs->calling_len = 0;
	dte_facs->called_len = 0;
	memset(dte_facs->called_ae, '\0', sizeof(dte_facs->called_ae));
	memset(dte_facs->calling_ae, '\0', sizeof(dte_facs->calling_ae));

	if (!pskb_may_pull(skb, 1))
	return 0;

	len = skb->data[0];

	if (!pskb_may_pull(skb, 1 + len))
	return -1;

	p = skb->data + 1;

	while (len > 0) {
	switch (*p & X25_FAC_CLASS_MASK) {
	case X25_FAC_CLASS_A:
	if (len < 2)
	return -1;
	switch (*p) {
	case X25_FAC_REVERSE:
	if((p[1] & 0x81) == 0x81) {
	facilities->reverse = p[1] & 0x81;
	*vc_fac_mask \|= X25_MASK_REVERSE;
	break;
	}

	if((p[1] & 0x01) == 0x01) {
	facilities->reverse = p[1] & 0x01;
	*vc_fac_mask \|= X25_MASK_REVERSE;
	break;
	}

	if((p[1] & 0x80) == 0x80) {
	facilities->reverse = p[1] & 0x80;
	*vc_fac_mask \|= X25_MASK_REVERSE;
	break;
	}

	if(p[1] == 0x00) {
	facilities->reverse
	= X25_DEFAULT_REVERSE;
	*vc_fac_mask \|= X25_MASK_REVERSE;
	break;
	}

	case X25_FAC_THROUGHPUT:
	facilities->throughput = p[1];
	*vc_fac_mask \|= X25_MASK_THROUGHPUT;
	break;
	case X25_MARKER:
	break;
	default:
	pr_debug("unknown facility "
	"%02X, value %02X\n",
	p[0], p[1]);
	break;
	}
	p += 2;
	len -= 2;
	break;
	case X25_FAC_CLASS_B:
	if (len < 3)
	return -1;
	switch (*p) {
	case X25_FAC_PACKET_SIZE:
	facilities->pacsize_in = p[1];
	facilities->pacsize_out = p[2];
	*vc_fac_mask \|= X25_MASK_PACKET_SIZE;
	break;
	case X25_FAC_WINDOW_SIZE:
	facilities->winsize_in = p[1];
	facilities->winsize_out = p[2];
	*vc_fac_mask \|= X25_MASK_WINDOW_SIZE;
	break;
	default:
	pr_debug("unknown facility "
	"%02X, values %02X, %02X\n",
	p[0], p[1], p[2]);
	break;
	}
	p += 3;
	len -= 3;
	break;
	case X25_FAC_CLASS_C:
	if (len < 4)
	return -1;
	pr_debug("unknown facility %02X, "
	"values %02X, %02X, %02X\n",
	p[0], p[1], p[2], p[3]);
	p += 4;
	len -= 4;
	break;
	case X25_FAC_CLASS_D:
	if (len < p[1] + 2)
	return -1;
	switch (*p) {
	case X25_FAC_CALLING_AE:
	if (p[1] > X25_MAX_DTE_FACIL_LEN \|\| p[1] <= 1)
	return -1;
	if (p[2] > X25_MAX_AE_LEN)
	return -1;
	dte_facs->calling_len = p[2];
	memcpy(dte_facs->calling_ae, &p[3], p[1] - 1);
	*vc_fac_mask \|= X25_MASK_CALLING_AE;
	break;
	case X25_FAC_CALLED_AE:
	if (p[1] > X25_MAX_DTE_FACIL_LEN \|\| p[1] <= 1)
	return -1;
	if (p[2] > X25_MAX_AE_LEN)
	return -1;
	dte_facs->called_len = p[2];
	memcpy(dte_facs->called_ae, &p[3], p[1] - 1);
	*vc_fac_mask \|= X25_MASK_CALLED_AE;
	break;
	default:
	pr_debug("unknown facility %02X,"
	"length %d\n", p[0], p[1]);
	break;
	}
	len -= p[1] + 2;
	p += p[1] + 2;
	break;
	}
	}

	return p - skb->data;
	}

	/*
	* Create a set of facilities.
	*/
	int x25_create_facilities(unsigned char *buffer,
	struct x25_facilities *facilities,
	struct x25_dte_facilities *dte_facs, unsigned long facil_mask)
	{
	unsigned char *p = buffer + 1;
	int len;

	if (!facil_mask) {
	/*
	* Length of the facilities field in call_req or
	* call_accept packets
	*/
	buffer[0] = 0;
	len = 1; /* 1 byte for the length field */
	return len;
	}

	if (facilities->reverse && (facil_mask & X25_MASK_REVERSE)) {
	*p++ = X25_FAC_REVERSE;
	*p++ = facilities->reverse;
	}

	if (facilities->throughput && (facil_mask & X25_MASK_THROUGHPUT)) {
	*p++ = X25_FAC_THROUGHPUT;
	*p++ = facilities->throughput;
	}

	if ((facilities->pacsize_in \|\| facilities->pacsize_out) &&
	(facil_mask & X25_MASK_PACKET_SIZE)) {
	*p++ = X25_FAC_PACKET_SIZE;
	*p++ = facilities->pacsize_in ? : facilities->pacsize_out;
	*p++ = facilities->pacsize_out ? : facilities->pacsize_in;
	}

	if ((facilities->winsize_in \|\| facilities->winsize_out) &&
	(facil_mask & X25_MASK_WINDOW_SIZE)) {
	*p++ = X25_FAC_WINDOW_SIZE;
	*p++ = facilities->winsize_in ? : facilities->winsize_out;
	*p++ = facilities->winsize_out ? : facilities->winsize_in;
	}

	if (facil_mask & (X25_MASK_CALLING_AE\|X25_MASK_CALLED_AE)) {
	*p++ = X25_MARKER;
	*p++ = X25_DTE_SERVICES;
	}

	if (dte_facs->calling_len && (facil_mask & X25_MASK_CALLING_AE)) {
	unsigned int bytecount = (dte_facs->calling_len + 1) >> 1;
	*p++ = X25_FAC_CALLING_AE;
	*p++ = 1 + bytecount;
	*p++ = dte_facs->calling_len;
	memcpy(p, dte_facs->calling_ae, bytecount);
	p += bytecount;
	}

	if (dte_facs->called_len && (facil_mask & X25_MASK_CALLED_AE)) {
	unsigned int bytecount = (dte_facs->called_len % 2) ?
	dte_facs->called_len / 2 + 1 :
	dte_facs->called_len / 2;
	*p++ = X25_FAC_CALLED_AE;
	*p++ = 1 + bytecount;
	*p++ = dte_facs->called_len;
	memcpy(p, dte_facs->called_ae, bytecount);
	p+=bytecount;
	}

	len = p - buffer;
	buffer[0] = len - 1;

	return len;
	}

	/*
	* Try to reach a compromise on a set of facilities.
	*
	* The only real problem is with reverse charging.
	*/
	int x25_negotiate_facilities(struct sk_buff skb, struct sock sk,
	struct x25_facilities new, struct x25_dte_facilities dte)
	{
	struct x25_sock *x25 = x25_sk(sk);
	struct x25_facilities *ours = &x25->facilities;
	struct x25_facilities theirs;
	int len;

	memset(&theirs, 0, sizeof(theirs));
	memcpy(new, ours, sizeof(*new));
	memset(dte, 0, sizeof(*dte));

	len = x25_parse_facilities(skb, &theirs, dte, &x25->vc_facil_mask);
	if (len < 0)
	return len;

	/*
	* They want reverse charging, we won't accept it.
	*/
	if ((theirs.reverse & 0x01 ) && (ours->reverse & 0x01)) {
	SOCK_DEBUG(sk, "X.25: rejecting reverse charging request\n");
	return -1;
	}

	new->reverse = theirs.reverse;

	if (theirs.throughput) {
	int theirs_in = theirs.throughput & 0x0f;
	int theirs_out = theirs.throughput & 0xf0;
	int ours_in = ours->throughput & 0x0f;
	int ours_out = ours->throughput & 0xf0;
	if (!ours_in \|\| theirs_in < ours_in) {
	SOCK_DEBUG(sk, "X.25: inbound throughput negotiated\n");
	new->throughput = (new->throughput & 0xf0) \| theirs_in;
	}
	if (!ours_out \|\| theirs_out < ours_out) {
	SOCK_DEBUG(sk,
	"X.25: outbound throughput negotiated\n");
	new->throughput = (new->throughput & 0x0f) \| theirs_out;
	}
	}

	if (theirs.pacsize_in && theirs.pacsize_out) {
	if (theirs.pacsize_in < ours->pacsize_in) {
	SOCK_DEBUG(sk, "X.25: packet size inwards negotiated down\n");
	new->pacsize_in = theirs.pacsize_in;
	}
	if (theirs.pacsize_out < ours->pacsize_out) {
	SOCK_DEBUG(sk, "X.25: packet size outwards negotiated down\n");
	new->pacsize_out = theirs.pacsize_out;
	}
	}

	if (theirs.winsize_in && theirs.winsize_out) {
	if (theirs.winsize_in < ours->winsize_in) {
	SOCK_DEBUG(sk, "X.25: window size inwards negotiated down\n");
	new->winsize_in = theirs.winsize_in;
	}
	if (theirs.winsize_out < ours->winsize_out) {
	SOCK_DEBUG(sk, "X.25: window size outwards negotiated down\n");
	new->winsize_out = theirs.winsize_out;
	}
	}

	return len;
	}

	/*
	* Limit values of certain facilities according to the capability of the
	* currently attached x25 link.
	*/
	void x25_limit_facilities(struct x25_facilities *facilities,
	struct x25_neigh *nb)
	{

	if (!nb->extended) {
	if (facilities->winsize_in > 7) {
	pr_debug("incoming winsize limited to 7\n");
	facilities->winsize_in = 7;
	}
	if (facilities->winsize_out > 7) {
	facilities->winsize_out = 7;
	pr_debug("outgoing winsize limited to 7\n");
	}
	}
	}