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implemented dns domain parser in a packet

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hyung-hwan
2020-02-12 10:06:05 +00:00
parent 42fe77bde5
commit d0906bb8ac
2 changed files with 102 additions and 55 deletions
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150
mio/lib/dns.c
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@ -639,65 +639,109 @@ int mio_svc_dnc_resolve (mio_svc_dnc_t* dnc, const mio_bch_t* qname, mio_dns_qty
/* ----------------------------------------------------------------------- */
static mio_uint8_t* parse_question (mio_t* mio, mio_uint8_t* dn, mio_uint8_t* pktend)
static mio_uint8_t* parse_domain_name (mio_t* mio, mio_uint8_t* ptr, mio_uint8_t* pktstart, mio_uint8_t* pktend)
{
mio_oow_t totlen, seglen;
mio_dns_qrtr_t* qrtr;
mio_uint8_t* xptr;
if (dn >= pktend)
{
mio_seterrbfmt (mio, MIO_EINVAL, "invalid packet");
return MIO_NULL;
}
if (ptr >= pktend) goto oops;
xptr = MIO_NULL;
totlen = 0;
while ((seglen = *dn++) > 0)
{
if (seglen > 64)
{
/* compressed. pointer to somewhere else */
/* TODO: */
}
totlen += seglen;
dn += seglen;
printf ("\t");
while ((seglen = *ptr++) > 0)
{
if (MIO_LIKELY(seglen < 64))
{
/* normal. 00XXXXXXXX */
normal:
printf ("[%.*s]", (int)seglen, ptr);
totlen += seglen;
ptr += seglen;
if (MIO_UNLIKELY(ptr >= pktend)) goto oops;
}
else if (seglen >= 192)
{
/* compressed. 11XXXXXXXX XXXXXXXX */
mio_oow_t offset;
if (MIO_UNLIKELY(ptr >= pktend)) goto oops; /* check before ptr++ in the next line */
offset = ((seglen & 0x3F) << 8) | *ptr++;
if (MIO_UNLIKELY(&pktstart[offset] >= pktend)) goto oops;
seglen = pktstart[offset];
if (seglen >= 64) goto oops; /* the pointed position must not contain another pointer */
if (!xptr) xptr = ptr; /* some later parts can also be a poitner again. so xptr, once set, must not be set again */
ptr = &pktstart[offset + 1];
if (MIO_UNLIKELY(ptr >= pktend)) goto oops;
goto normal;
}
else if (seglen >= 128)
{
/* 128 to 191. 10XXXXXXXX */
goto oops;
}
else
{
/* 64 to 127. 01XXXXXXXX */
goto oops;
}
}
qrtr = (mio_dns_qrtr_t*)dn;
dn += MIO_SIZEOF(*qrtr);
printf ("\n");
return xptr? xptr: ptr;
return dn;
oops:
mio_seterrbfmt (mio, MIO_EINVAL, "invalid packet");
return MIO_NULL;
}
static mio_uint8_t* parse_answer (mio_t* mio, mio_uint8_t* dn, mio_uint8_t* pktend)
static mio_uint8_t* parse_question (mio_t* mio, mio_uint8_t* ptr, mio_uint8_t* pktstart, mio_uint8_t* pktend)
{
mio_dns_qrtr_t* qrtr;
ptr = parse_domain_name(mio, ptr, pktstart, pktend);
if (!ptr) return MIO_NULL;
qrtr = (mio_dns_qrtr_t*)ptr;
ptr += MIO_SIZEOF(*qrtr);
if (MIO_UNLIKELY(ptr >= pktend)) goto oops;
return ptr;
oops:
mio_seterrbfmt (mio, MIO_EINVAL, "invalid packet");
return MIO_NULL;
}
static mio_uint8_t* parse_answer (mio_t* mio, mio_uint8_t* ptr, mio_uint8_t* pktstart, mio_uint8_t* pktend)
{
mio_oow_t totlen, seglen;
mio_dns_rrtr_t* rrtr;
if (dn >= pktend)
{
mio_seterrbfmt (mio, MIO_EINVAL, "invalid packet");
return MIO_NULL;
}
//printf ("pktstart = %p pktend = %p, ptr = %p\n", pktstart, pktend, ptr);
ptr = parse_domain_name(mio, ptr, pktstart, pktend);
if (!ptr) return MIO_NULL;
totlen = 0;
while ((seglen = *dn++) > 0)
{
totlen += seglen;
dn += seglen;
}
rrtr = (mio_dns_rrtr_t*)ptr;
ptr += MIO_SIZEOF(*rrtr) + mio_ntoh16(rrtr->dlen);
if (MIO_UNLIKELY(ptr >= pktend)) goto oops;
//printf ("rrtr->dlen => %d\n", mio_ntoh16(rrtr->dlen));
rrtr = (mio_dns_rrtr_t*)dn;
dn += MIO_SIZEOF(*rrtr) + rrtr->dlen;
return ptr;
return dn;
oops:
mio_seterrbfmt (mio, MIO_EINVAL, "invalid packet");
return MIO_NULL;
}
int mio_dns_parse_packet (mio_svc_dnc_t* dnc, mio_dns_pkt_t* pkt, mio_oow_t len, mio_dns_bdns_t* bdns)
{
mio_t* mio = dnc->mio;
mio_uint16_t i, rrc;
mio_uint8_t* dn;
mio_uint8_t* ptr;
mio_uint8_t* pktend = (mio_uint8_t*)pkt + len;
MIO_ASSERT (mio, len >= MIO_SIZEOF(*pkt));
@ -714,50 +758,48 @@ int mio_dns_parse_packet (mio_svc_dnc_t* dnc, mio_dns_pkt_t* pkt, mio_oow_t len,
bdns->cd = pkt->cd & 0x01;
bdns->rcode = pkt->rcode & 0x0F;
/*
bdns->qdcount = mio_ntoh16(pkt->qdcount);
bdns->ancount = mio_ntoh16(pkt->ancount);
bdns->nscount = mio_ntoh16(pkt->nscount);
bdns->arcount = mio_ntoh16(pkt->arcount);
*/
dn = (mio_uint8_t*)(pkt + 1);
ptr = (mio_uint8_t*)(pkt + 1);
rrc = mio_ntoh16(pkt->qdcount);
printf ("question %d\n", rrc);
for (i = 0; i < rrc; i++)
{
dn = parse_question(mio, dn, pktend);
if (!dn) return -1;
ptr = parse_question(mio, ptr, (mio_uint8_t*)pkt, pktend);
if (!ptr) return -1;
}
rrc = mio_ntoh16(pkt->ancount);
printf ("answer %d\n", rrc);
for (i = 0; i < rrc; i++)
{
dn = parse_answer(mio, dn, pktend);
if (!dn) return -1;
ptr = parse_answer(mio, ptr, (mio_uint8_t*)pkt, pktend);
if (!ptr) return -1;
}
rrc = mio_ntoh16(pkt->nscount);
printf ("authority %d\n", rrc);
for (i = 0; i < rrc; i++)
{
dn = parse_answer(mio, dn, pktend);
if (!dn) return -1;
ptr = parse_answer(mio, ptr, (mio_uint8_t*)pkt, pktend);
if (!ptr) return -1;
}
rrc = mio_ntoh16(pkt->arcount);
printf ("additional %d\n", rrc);
for (i = 0; i < rrc; i++)
{
dn = parse_answer(mio, dn, pktend);
if (!dn) return -1;
ptr = parse_answer(mio, ptr, (mio_uint8_t*)pkt, pktend);
if (!ptr) return -1;
}
printf ("packet ok...\n");
#if 0
for (i = 0; i < bdns->arcount; i++)
{
#if 0
if (*dn == 0)
if (*ptr == 0)
{
rrtr = (mio_dns_rrtr_t*)(dn + 1);
rrtr = (mio_ptrs_rrtr_t*)(ptr + 1);
if (rrtr->qtype == MIO_CONST_HTON16(MIO_DNS_QTYPE_OPT)
{
/* edns */