ip_nat_snmp_basic.c

linux-2.6.15.6

		return 0;
	}
	
	if (subid < 40) {
		optr [0] = 0;
		optr [1] = subid;
	} else if (subid < 80) {
		optr [0] = 1;
		optr [1] = subid - 40;
	} else {
		optr [0] = 2;
		optr [1] = subid - 80;
	}
	
	*len = 2;
	optr += 2;
	
	while (ctx->pointer < eoc) {
		if (++(*len) > size) {
			ctx->error = ASN1_ERR_DEC_BADVALUE;
			kfree(*oid);
			*oid = NULL;
			return 0;
		}
		
		if (!asn1_subid_decode(ctx, optr++)) {
			kfree(*oid);
			*oid = NULL;
			return 0;
		}
	}
	return 1;
}

/*****************************************************************************
 *
 * SNMP decoding routines (gxsnmp author Dirk Wisse)
 *
 *****************************************************************************/

/* SNMP Versions */
#define SNMP_V1				0
#define SNMP_V2C			1
#define SNMP_V2				2
#define SNMP_V3				3

/* Default Sizes */
#define SNMP_SIZE_COMM			256
#define SNMP_SIZE_OBJECTID		128
#define SNMP_SIZE_BUFCHR		256
#define SNMP_SIZE_BUFINT		128
#define SNMP_SIZE_SMALLOBJECTID		16

/* Requests */
#define SNMP_PDU_GET			0
#define SNMP_PDU_NEXT			1
#define SNMP_PDU_RESPONSE		2
#define SNMP_PDU_SET			3
#define SNMP_PDU_TRAP1			4
#define SNMP_PDU_BULK			5
#define SNMP_PDU_INFORM			6
#define SNMP_PDU_TRAP2			7

/* Errors */
#define SNMP_NOERROR			0
#define SNMP_TOOBIG			1
#define SNMP_NOSUCHNAME			2
#define SNMP_BADVALUE			3
#define SNMP_READONLY			4
#define SNMP_GENERROR			5
#define SNMP_NOACCESS			6
#define SNMP_WRONGTYPE			7
#define SNMP_WRONGLENGTH		8
#define SNMP_WRONGENCODING		9
#define SNMP_WRONGVALUE			10
#define SNMP_NOCREATION			11
#define SNMP_INCONSISTENTVALUE		12
#define SNMP_RESOURCEUNAVAILABLE	13
#define SNMP_COMMITFAILED		14
#define SNMP_UNDOFAILED			15
#define SNMP_AUTHORIZATIONERROR		16
#define SNMP_NOTWRITABLE		17
#define SNMP_INCONSISTENTNAME		18

/* General SNMP V1 Traps */
#define SNMP_TRAP_COLDSTART		0
#define SNMP_TRAP_WARMSTART		1
#define SNMP_TRAP_LINKDOWN		2
#define SNMP_TRAP_LINKUP		3
#define SNMP_TRAP_AUTFAILURE		4
#define SNMP_TRAP_EQPNEIGHBORLOSS	5
#define SNMP_TRAP_ENTSPECIFIC		6

/* SNMPv1 Types */
#define SNMP_NULL                0
#define SNMP_INTEGER             1    /* l  */
#define SNMP_OCTETSTR            2    /* c  */
#define SNMP_DISPLAYSTR          2    /* c  */
#define SNMP_OBJECTID            3    /* ul */
#define SNMP_IPADDR              4    /* uc */
#define SNMP_COUNTER             5    /* ul */
#define SNMP_GAUGE               6    /* ul */
#define SNMP_TIMETICKS           7    /* ul */
#define SNMP_OPAQUE              8    /* c  */

/* Additional SNMPv2 Types */
#define SNMP_UINTEGER            5    /* ul */
#define SNMP_BITSTR              9    /* uc */
#define SNMP_NSAP               10    /* uc */
#define SNMP_COUNTER64          11    /* ul */
#define SNMP_NOSUCHOBJECT       12
#define SNMP_NOSUCHINSTANCE     13
#define SNMP_ENDOFMIBVIEW       14

union snmp_syntax
{
	unsigned char uc[0];	/* 8 bit unsigned */
	char c[0];		/* 8 bit signed */
	unsigned long ul[0];	/* 32 bit unsigned */
	long l[0];		/* 32 bit signed */
};

struct snmp_object
{
	unsigned long *id;
	unsigned int id_len;
	unsigned short type;
	unsigned int syntax_len;
	union snmp_syntax syntax;
};

struct snmp_request
{
	unsigned long id;
	unsigned int error_status;
	unsigned int error_index;
};

struct snmp_v1_trap
{
	unsigned long *id;
	unsigned int id_len;
	unsigned long ip_address;	/* pointer  */
	unsigned int general;
	unsigned int specific;
	unsigned long time;
};

/* SNMP types */
#define SNMP_IPA    0
#define SNMP_CNT    1
#define SNMP_GGE    2
#define SNMP_TIT    3
#define SNMP_OPQ    4
#define SNMP_C64    6

/* SNMP errors */
#define SERR_NSO    0
#define SERR_NSI    1
#define SERR_EOM    2

static inline void mangle_address(unsigned char *begin,
                                  unsigned char *addr,
                                  const struct oct1_map *map,
                                  u_int16_t *check);
struct snmp_cnv
{
	unsigned int class;
	unsigned int tag;
	int syntax;
};

static struct snmp_cnv snmp_conv [] =
{
	{ASN1_UNI, ASN1_NUL, SNMP_NULL},
	{ASN1_UNI, ASN1_INT, SNMP_INTEGER},
	{ASN1_UNI, ASN1_OTS, SNMP_OCTETSTR},
	{ASN1_UNI, ASN1_OTS, SNMP_DISPLAYSTR},
	{ASN1_UNI, ASN1_OJI, SNMP_OBJECTID},
	{ASN1_APL, SNMP_IPA, SNMP_IPADDR},
	{ASN1_APL, SNMP_CNT, SNMP_COUNTER},	/* Counter32 */
	{ASN1_APL, SNMP_GGE, SNMP_GAUGE},	/* Gauge32 == Unsigned32  */
	{ASN1_APL, SNMP_TIT, SNMP_TIMETICKS},
	{ASN1_APL, SNMP_OPQ, SNMP_OPAQUE},
	
	/* SNMPv2 data types and errors */
	{ASN1_UNI, ASN1_BTS, SNMP_BITSTR},
	{ASN1_APL, SNMP_C64, SNMP_COUNTER64},
	{ASN1_CTX, SERR_NSO, SNMP_NOSUCHOBJECT},
	{ASN1_CTX, SERR_NSI, SNMP_NOSUCHINSTANCE},
	{ASN1_CTX, SERR_EOM, SNMP_ENDOFMIBVIEW},
	{0,       0,       -1}
};

static unsigned char snmp_tag_cls2syntax(unsigned int tag,
                                         unsigned int cls,
                                         unsigned short *syntax)
{
	struct snmp_cnv *cnv;
	
	cnv = snmp_conv;
	
	while (cnv->syntax != -1) {
		if (cnv->tag == tag && cnv->class == cls) {
			*syntax = cnv->syntax;
			return 1;
		}
		cnv++;
	}
	return 0;
}

static unsigned char snmp_object_decode(struct asn1_ctx *ctx,
                                        struct snmp_object **obj)
{
	unsigned int cls, con, tag, len, idlen;
	unsigned short type;
	unsigned char *eoc, *end, *p;
	unsigned long *lp, *id;
	unsigned long ul;
	long  l;
	
	*obj = NULL;
	id = NULL;
	
	if (!asn1_header_decode(ctx, &eoc, &cls, &con, &tag))
		return 0;
		
	if (cls != ASN1_UNI || con != ASN1_CON || tag != ASN1_SEQ)
		return 0;
	
	if (!asn1_header_decode(ctx, &end, &cls, &con, &tag))
		return 0;
	
	if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_OJI)
		return 0;
	
	if (!asn1_oid_decode(ctx, end, &id, &idlen))
		return 0;
		
	if (!asn1_header_decode(ctx, &end, &cls, &con, &tag)) {
		kfree(id);
		return 0;
	}
	
	if (con != ASN1_PRI) {
		kfree(id);
		return 0;
	}
	
	if (!snmp_tag_cls2syntax(tag, cls, &type)) {
		kfree(id);
		return 0;
	}
	
	switch (type) {
		case SNMP_INTEGER:
			len = sizeof(long);
			if (!asn1_long_decode(ctx, end, &l)) {
				kfree(id);
				return 0;
			}
			*obj = kmalloc(sizeof(struct snmp_object) + len,
			               GFP_ATOMIC);
			if (*obj == NULL) {
				kfree(id);
				if (net_ratelimit())
					printk("OOM in bsalg (%d)\n", __LINE__);
				return 0;
			}
			(*obj)->syntax.l[0] = l;
			break;
		case SNMP_OCTETSTR:
		case SNMP_OPAQUE:
			if (!asn1_octets_decode(ctx, end, &p, &len)) {
				kfree(id);
				return 0;
			}
			*obj = kmalloc(sizeof(struct snmp_object) + len,
			               GFP_ATOMIC);
			if (*obj == NULL) {
				kfree(id);
				if (net_ratelimit())
					printk("OOM in bsalg (%d)\n", __LINE__);
				return 0;
			}
			memcpy((*obj)->syntax.c, p, len);
			kfree(p);
			break;
		case SNMP_NULL:
		case SNMP_NOSUCHOBJECT:
		case SNMP_NOSUCHINSTANCE:
		case SNMP_ENDOFMIBVIEW:
			len = 0;
			*obj = kmalloc(sizeof(struct snmp_object), GFP_ATOMIC);
			if (*obj == NULL) {
				kfree(id);
				if (net_ratelimit())
					printk("OOM in bsalg (%d)\n", __LINE__);
				return 0;
			}
			if (!asn1_null_decode(ctx, end)) {
				kfree(id);
				kfree(*obj);
				*obj = NULL;
				return 0;
			}
			break;
		case SNMP_OBJECTID:
			if (!asn1_oid_decode(ctx, end, (unsigned long **)&lp, &len)) {
				kfree(id);
				return 0;
			}
			len *= sizeof(unsigned long);
			*obj = kmalloc(sizeof(struct snmp_object) + len, GFP_ATOMIC);
			if (*obj == NULL) {
				kfree(id);
				if (net_ratelimit())
					printk("OOM in bsalg (%d)\n", __LINE__);
				return 0;
			}
			memcpy((*obj)->syntax.ul, lp, len);
			kfree(lp);
			break;
		case SNMP_IPADDR:
			if (!asn1_octets_decode(ctx, end, &p, &len)) {
				kfree(id);
				return 0;
			}
			if (len != 4) {
				kfree(p);
				kfree(id);
				return 0;
			}
			*obj = kmalloc(sizeof(struct snmp_object) + len, GFP_ATOMIC);
			if (*obj == NULL) {
				kfree(p);
				kfree(id);
				if (net_ratelimit())
					printk("OOM in bsalg (%d)\n", __LINE__);
				return 0;
			}
			memcpy((*obj)->syntax.uc, p, len);
			kfree(p);
			break;
		case SNMP_COUNTER:
		case SNMP_GAUGE:
		case SNMP_TIMETICKS:
			len = sizeof(unsigned long);
			if (!asn1_ulong_decode(ctx, end, &ul)) {
				kfree(id);
				return 0;
			}
			*obj = kmalloc(sizeof(struct snmp_object) + len, GFP_ATOMIC);
			if (*obj == NULL) {
				kfree(id);
				if (net_ratelimit())
					printk("OOM in bsalg (%d)\n", __LINE__);
				return 0;
			}
			(*obj)->syntax.ul[0] = ul;
			break;
		default:
			kfree(id);
			return 0;
	}
	
	(*obj)->syntax_len = len;
	(*obj)->type = type;
	(*obj)->id = id;
	(*obj)->id_len = idlen;
	
	if (!asn1_eoc_decode(ctx, eoc)) {
		kfree(id);
		kfree(*obj);
		*obj = NULL;
		return 0;
	}
	return 1;
}

static unsigned char snmp_request_decode(struct asn1_ctx *ctx,
                                         struct snmp_request *request)
{
	unsigned int cls, con, tag;
	unsigned char *end;
	
	if (!asn1_header_decode(ctx, &end, &cls, &con, &tag))
		return 0;
		
	if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_INT)
		return 0;
		
	if (!asn1_ulong_decode(ctx, end, &request->id))
		return 0;
		
	if (!asn1_header_decode(ctx, &end, &cls, &con, &tag))
		return 0;
		
	if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_INT)
		return 0;
		
	if (!asn1_uint_decode(ctx, end, &request->error_status))
		return 0;
		
	if (!asn1_header_decode(ctx, &end, &cls, &con, &tag))
		return 0;
		
	if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_INT)
		return 0;
		
	if (!asn1_uint_decode(ctx, end, &request->error_index))
		return 0;
	
	return 1;
}

/* 
 * Fast checksum update for possibly oddly-aligned UDP byte, from the
 * code example in the draft.
 */
static void fast_csum(unsigned char *csum,
                      const unsigned char *optr,
                      const unsigned char *nptr,
                      int odd)
{
	long x, old, new;
	
	x = csum[0] * 256 + csum[1];
	
	x =~ x & 0xFFFF;
	
	if (odd) old = optr[0] * 256;
	else old = optr[0];
	
	x -= old & 0xFFFF;
	if (x <= 0) {
		x--;
		x &= 0xFFFF;
	}
	
	if (odd) new = nptr[0] * 256;
	else new = nptr[0];
	
	x += new & 0xFFFF;
	if (x & 0x10000) {
		x++;
		x &= 0xFFFF;
	}