static int process_rrsection(jdns_list_t *dest, int count, const unsigned char *data, int size, const unsigned char **bufp)
{
int n;
int offset, at;
jdns_string_t *name = 0;
const unsigned char *buf;
buf = *bufp;
for(n = 0; n < count; ++n)
{
jdns_packet_resource_t *r;
offset = buf - data;
at = 0;
if(!readlabel(data + offset, size - offset, data, size, &at, &name))
goto error;
offset += at;
// need 10 more bytes
if(offset + 10 > size)
goto error;
buf = data + offset;
r = jdns_packet_resource_new();
r->qname = name;
name = 0;
r->qtype = net2short(&buf);
r->qclass = net2short(&buf);
r->ttl = net2long(&buf);
r->rdlength = net2short(&buf);
offset = buf - data;
// make sure we have enough for the rdata
if(size - offset < r->rdlength)
{
jdns_packet_resource_delete(r);
goto error;
}
r->rdata = jdns_copy_array(buf, r->rdlength);
buf += r->rdlength;
jdns_list_insert_value(dest, r, -1);
jdns_packet_resource_delete(r);
}
*bufp = buf;
return 1;
error:
jdns_string_delete(name);
return 0;
}
static int process_qsection(jdns_list_t *dest, int count, const unsigned char *data, int size, const unsigned char **bufp)
{
int n;
int offset, at;
jdns_string_t *name = 0;
const unsigned char *buf;
buf = *bufp;
for(n = 0; n < count; ++n)
{
jdns_packet_question_t *q;
offset = buf - data;
at = 0;
if(!readlabel(data + offset, size - offset, data, size, &at, &name))
goto error;
offset += at;
// need 4 more bytes
if(size - offset < 4)
goto error;
buf = data + offset;
q = jdns_packet_question_new();
q->qname = name;
name = 0;
q->qtype = net2short(&buf);
q->qclass = net2short(&buf);
jdns_list_insert_value(dest, q, -1);
jdns_packet_question_delete(q);
}
*bufp = buf;
return 1;
error:
jdns_string_delete(name);
return 0;
}
void message_parse(struct message *m, unsigned char *packet)
{
unsigned char *buf;
int i;
if(packet == 0 || m == 0) return;
// keep all our mem in one (aligned) block for easy freeing
#define my(x,y) while(m->_len&7) m->_len++; x = (void*)(m->_packet + m->_len); m->_len += y;
// header stuff bit crap
m->_buf = buf = packet;
m->id = net2short(&buf);
if(buf[0] & 0x80) m->header.qr = 1;
m->header.opcode = (buf[0] & 0x78) >> 3;
if(buf[0] & 0x04) m->header.aa = 1;
if(buf[0] & 0x02) m->header.tc = 1;
if(buf[0] & 0x01) m->header.rd = 1;
if(buf[1] & 0x80) m->header.ra = 1;
m->header.z = (buf[1] & 0x70) >> 4;
m->header.rcode = buf[1] & 0x0F;
buf += 2;
m->qdcount = net2short(&buf);
if(m->_len + (sizeof(struct question) * m->qdcount) > MAX_PACKET_LEN - 8) { m->qdcount = 0; return; }
m->ancount = net2short(&buf);
if(m->_len + (sizeof(struct resource) * m->ancount) > MAX_PACKET_LEN - 8) { m->ancount = 0; return; }
m->nscount = net2short(&buf);
if(m->_len + (sizeof(struct resource) * m->nscount) > MAX_PACKET_LEN - 8) { m->nscount = 0; return; }
m->arcount = net2short(&buf);
if(m->_len + (sizeof(struct resource) * m->arcount) > MAX_PACKET_LEN - 8) { m->arcount = 0; return; }
// process questions
my(m->qd, sizeof(struct question) * m->qdcount);
for(i=0; i < m->qdcount; i++)
{
_label(m, &buf, &(m->qd[i].name));
m->qd[i].type = net2short(&buf);
m->qd[i].rr_class = net2short(&buf);
}
// process rrs
my(m->an, sizeof(struct resource) * m->ancount);
my(m->ns, sizeof(struct resource) * m->nscount);
my(m->ar, sizeof(struct resource) * m->arcount);
if(! _rrparse(m,m->an,m->ancount,&buf))
m->ancount = 0; // some error in parsing, set those counts to 0
if(! _rrparse(m,m->ns,m->nscount,&buf))
m->nscount = 0;
if(! _rrparse(m,m->ar,m->arcount,&buf))
m->arcount = 0;
}
/**
Return 1 on success, 0 on failure.
*/
int _rrparse(struct message *m, struct resource *rr, int count, unsigned char **bufp)
{
int i;
for(i=0; i < count; i++)
{
_label(m, bufp, &(rr[i].name));
rr[i].type = net2short(bufp);
rr[i].rr_class = net2short(bufp);
rr[i].ttl = net2long(bufp);
rr[i].rdlength = net2short(bufp);
// if not going to overflow, make copy of source rdata
if(rr[i].rdlength + (*bufp - m->_buf) > MAX_PACKET_LEN || m->_len + rr[i].rdlength > MAX_PACKET_LEN) return 0;
rr[i].rdata = m->_packet + m->_len;
m->_len += rr[i].rdlength;
memcpy(rr[i].rdata,*bufp,rr[i].rdlength);
// parse commonly known ones
switch(rr[i].type)
{
case 1:
if(m->_len + 16 > MAX_PACKET_LEN) return 0;
rr[i].known.a.name = m->_packet + m->_len;
m->_len += 16;
sprintf(rr[i].known.a.name,"%d.%d.%d.%d",(*bufp)[0],(*bufp)[1],(*bufp)[2],(*bufp)[3]);
rr[i].known.a.ip = net2long(bufp);
break;
case 2:
_label(m, bufp, &(rr[i].known.ns.name));
break;
case 5:
_label(m, bufp, &(rr[i].known.cname.name));
break;
case 12:
_label(m, bufp, &(rr[i].known.ptr.name));
break;
case 33:
rr[i].known.srv.priority = net2short(bufp);
rr[i].known.srv.weight = net2short(bufp);
rr[i].known.srv.port = net2short(bufp);
_label(m, bufp, &(rr[i].known.srv.name));
break;
default:
*bufp += rr[i].rdlength;
}
}
return 1;
}
int jdns_packet_import(jdns_packet_t **a, const unsigned char *data, int size)
{
jdns_packet_t *tmp = 0;
const unsigned char *buf;
// need at least some data
if(!data || size == 0)
return 0;
// header (id + options + item counts) is 12 bytes
if(size < 12)
goto error;
tmp = jdns_packet_new();
buf = data;
// id
tmp->id = net2short(&buf);
// options
if(buf[0] & 0x80) // qr is bit 7
tmp->opts.qr = 1;
tmp->opts.opcode = (buf[0] & 0x78) >> 3; // opcode is bits 6,5,4,3
if(buf[0] & 0x04) // aa is bit 2
tmp->opts.aa = 1;
if(buf[0] & 0x02) // tc is bit 1
tmp->opts.tc = 1;
if(buf[0] & 0x01) // rd is bit 0
tmp->opts.rd = 1;
if(buf[1] & 0x80) // ra is bit 7 (second byte)
tmp->opts.ra = 1;
tmp->opts.z = (buf[1] & 0x70) >> 4; // z is bits 6,5,4
tmp->opts.rcode = buf[1] & 0x0f; // rcode is bits 3,2,1,0
buf += 2;
// item counts
tmp->qdcount = net2short(&buf);
tmp->ancount = net2short(&buf);
tmp->nscount = net2short(&buf);
tmp->arcount = net2short(&buf);
// if these fail, we don't count them as errors, since the packet
// might have been truncated
if(!process_qsection(tmp->questions, tmp->qdcount, data, size, &buf))
goto skip;
if(!process_rrsection(tmp->answerRecords, tmp->ancount, data, size, &buf))
goto skip;
if(!process_rrsection(tmp->authorityRecords, tmp->nscount, data, size, &buf))
goto skip;
if(!process_rrsection(tmp->additionalRecords, tmp->arcount, data, size, &buf))
goto skip;
tmp->fully_parsed = 1;
skip:
// keep the raw data for reference during rdata parsing
tmp->raw_size = size;
tmp->raw_data = jdns_copy_array(data, size);
*a = tmp;
return 1;
error:
jdns_packet_delete(tmp);
return 0;
}
