/*------------------------------------------------------------------------
* snb2a - convert the list of bindings from internal form into ASN.1
*------------------------------------------------------------------------
*/
int
snb2a(struct req_desc *rqdp)
{
register u_char *bp;
int len;
struct snbentry *bl;
u_char *ap;
for (bl = rqdp->bindlf; bl; bl = bl->sb_next) {
bp = snmpbuff; /* used for temporary working space */
*bp++ = ASN1_OBJID;
bp += a1writeoid(bp, &bl->sb_oid);
bp += a1writeval(bl, bp);
/*
* We need to allocate bytes in sb_a1str but can't do it
* until we know how many bytes it takes to write the
* length of the binding, so we write that length into
* snmpbuff at the end of the binding. Then we can alloc
* space, and transfer the data.
*/
len = a1writelen(bp, bp - snmpbuff);
bl->sb_a1slen = bp - snmpbuff + len + 1;
ap = bl->sb_a1str = (u_char *) getmem(bl->sb_a1slen);
bl->sb_a1dynstr = TRUE; /* dynamically allocated */
*ap++ = ASN1_SEQ;
memcpy(ap, bp, len); /* write in the length spec. */
ap += len;
memcpy(ap, snmpbuff, bp - snmpbuff);
}
return OK;
}
/*------------------------------------------------------------------------
* a1writeval - convert the value of a variable into ASN.1 equivalent.
*------------------------------------------------------------------------
*/
int
a1writeval(struct snbentry *bl, u_char *bp)
{
u_char *origbp;
origbp = bp;
*bp++ = SVTYPE(bl);
switch(SVTYPE(bl)) {
case ASN1_INT:
case ASN1_COUNTER:
case ASN1_GAUGE:
case ASN1_TIMETICKS:
bp += a1writeint(SVINT(bl), bp, SVTYPE(bl));
break;
case ASN1_NULL:
*bp++ = (u_char) 0;
break;
case ASN1_OCTSTR:
bp += a1writelen(bp, SVSTRLEN(bl));
memcpy(bp, SVSTR(bl), SVSTRLEN(bl));
bp += SVSTRLEN(bl);
freemem(SVSTR(bl), SVSTRLEN(bl));
break;
case ASN1_IPADDR:
*bp++ = IP_ALEN;
memcpy(bp, &SVIPADDR(bl), IP_ALEN);
bp += IP_ALEN;
break;
case ASN1_OBJID:
bp += a1writeoid(bp, &bl->sb_val.sv_val.sv_oid);
break;
default:
break;
}
return bp - origbp;
}
/*------------------------------------------------------------------------
* mksnmp - make an snmp packet and return its length
*------------------------------------------------------------------------
*/
int
mksnmp(struct req_desc *rqdp, u_char *snmppack, u_char pdutype)
{
register u_char *pp, *cp;
struct snbentry *bl;
u_char tmpbuff[40];
int len, mtu, estlen;
pp = snmpbuff;
if (rqdp->reqidlen == 0) { /* if id len == 0, get new reqid */
memcpy(rqdp->reqid, (char *) &clktime, sizeof(clktime));
rqdp->reqidlen = sizeof(clktime);
}
snb2a(rqdp); /* convert bindings to ASN.1 notation */
/* check total length of the packet to be created */
mtu = IP_MAXLEN;
/* add up total length of ASN.1 representations of variables */
for (estlen=0, bl=rqdp->bindlf; estlen<mtu && bl; bl=bl->sb_next)
estlen += bl->sb_a1slen;
/*
* if too long, or if adding the header makes it too long,
* set error status to tooBig and return
*/
if (bl || (estlen + SNMAXHLEN >= mtu)) {
rqdp->err_stat = SERR_TOO_BIG;
rqdp->err_idx = 0;
return SYSERR;
}
/* go backwards through snbentry, writing out the bindings */
for (bl=rqdp->bindle; bl; bl=bl->sb_prev) {
cp = &bl->sb_a1str[bl->sb_a1slen-1];
while (cp >= bl->sb_a1str)
*pp++ = *cp--;
}
/* write the length of the bindings and an ASN1_SEQ type */
len = a1writelen(tmpbuff, pp - snmpbuff);
for (cp = &tmpbuff[len-1]; cp >= tmpbuff; )
*pp++ = *cp--;
*pp++ = ASN1_SEQ;
/* write the error index and error status -- 1 byte integers */
*pp++ = (u_char) rqdp->err_idx;
*pp++ = (u_char) 1;
*pp++ = ASN1_INT;
*pp++ = (u_char) rqdp->err_stat;
*pp++ = (u_char) 1;
*pp++ = ASN1_INT;
/* write the request id, its length, and its type */
for (cp = &rqdp->reqid[rqdp->reqidlen-1]; cp >= rqdp->reqid; )
*pp++ = *cp--;
*pp++ = rqdp->reqidlen;
*pp++ = ASN1_INT;
/* write the packet length and pdutype */
len = a1writelen(tmpbuff, pp - snmpbuff);
for (cp = &tmpbuff[len-1]; cp >= tmpbuff; )
*pp++ = *cp--;
*pp++ = pdutype;
/* write the community and the version */
memcpy(pp, SNVCBACK, SNVCLEN);
pp += SNVCLEN;
/* write the total packet length */
len = a1writelen(tmpbuff, pp - snmpbuff);
for (cp = &tmpbuff[len-1]; cp >= tmpbuff; )
*pp++ = *cp--;
*pp++ = ASN1_SEQ;
/* reverse the entire finished packet */
for (--pp, cp = snmppack; pp >= snmpbuff; )
*cp++ = *pp--;
return cp - snmppack;
}
