static int append_qsection(const jdns_list_t *src, int at, int left, unsigned char **bufp, jdns_list_t *lookup)
{
unsigned char *buf, *start, *last;
int n;
buf = *bufp;
start = buf - at;
last = buf + left;
for(n = 0; n < src->count; ++n)
{
jdns_packet_question_t *q = (jdns_packet_question_t *)src->item[n];
if(!writelabel(q->qname, buf - start, last - buf, &buf, lookup))
goto error;
if(buf + 4 > last)
goto error;
short2net(q->qtype, &buf);
short2net(q->qclass, &buf);
}
*bufp = buf;
return 1;
error:
return 0;
}
static int append_rrsection(const jdns_list_t *src, int at, int left, unsigned char **bufp, jdns_list_t *lookup)
{
unsigned char *buf, *start, *last, *rdlengthp;
int n, i, rdlength;
buf = *bufp;
start = buf - at;
last = buf + left;
for(n = 0; n < src->count; ++n)
{
jdns_packet_resource_t *r = (jdns_packet_resource_t *)src->item[n];
if(!writelabel(r->qname, buf - start, last - buf, &buf, lookup))
goto error;
if(buf + 10 > last)
goto error;
short2net(r->qtype, &buf);
short2net(r->qclass, &buf);
long2net(r->ttl, &buf);
// skip over rdlength
rdlengthp = buf;
buf += 2;
// play write log
rdlength = 0;
for(i = 0; i < r->writelog->count; ++i)
{
jdns_packet_write_t *write = (jdns_packet_write_t *)r->writelog->item[i];
if(write->type == JDNS_PACKET_WRITE_RAW)
{
if(buf + write->value->size > last)
goto error;
memcpy(buf, write->value->data, write->value->size);
buf += write->value->size;
}
else // JDNS_PACKET_WRITE_NAME
{
if(!writelabel(write->value, buf - start, last - buf, &buf, lookup))
goto error;
}
}
i = buf - rdlengthp; // should be rdata size + 2
short2net((unsigned short int)(i - 2), &rdlengthp);
}
*bufp = buf;
return 1;
error:
return 0;
}
// nasty, convert host into label using compression
int _host(struct message *m, unsigned char **bufp, unsigned char *name)
{
unsigned char label[256], *l;
int len = 0, x = 1, y = 0, last = 0;
if(name == 0) return 0;
// make our label
while(name[y])
{
if(name[y] == '.')
{
if(!name[y+1]) break;
label[last] = x - (last + 1);
last = x;
}else{
label[x] = name[y];
}
if(x++ == 255) return 0;
y++;
}
label[last] = x - (last + 1);
if(x == 1) x--; // special case, bad names, but handle correctly
len = x + 1;
label[x] = 0; // always terminate w/ a 0
// double-loop checking each label against all m->_labels for match
for(x = 0; label[x]; x += label[x] + 1)
{
for(y = 0; m->_labels[y]; y++)
if(_lmatch(m,label+x,m->_labels[y]))
{
// matching label, set up pointer
l = label + x;
short2net(m->_labels[y] - m->_packet, &l);
label[x] |= 0xc0;
len = x + 2;
break;
}
if(label[x] & 0xc0) break;
}
// copy into buffer, point there now
memcpy(*bufp,label,len);
l = *bufp;
*bufp += len;
// for each new label, store it's location for future compression
for(x = 0; l[x]; x += l[x] + 1)
{
if(l[x] & 0xc0) break;
if(m->_label + 1 >= 19) break;
m->_labels[m->_label++] = l + x;
}
return len;
}
int jdns_packet_export(jdns_packet_t *a, int maxsize)
{
unsigned char *block = 0;
unsigned char *buf, *last;
unsigned char c;
int size;
jdns_list_t *lookup = 0; // to hold jdns_packet_label_t
// clear out any existing raw data before we begin
if(a->raw_data)
{
jdns_free(a->raw_data);
a->raw_data = 0;
a->raw_size = 0;
}
// preallocate
size = maxsize;
block = (unsigned char *)jdns_alloc(size);
memset(block, 0, size);
buf = block;
last = block + size;
if(size < 12)
goto error;
short2net(a->id, &buf);
if(a->opts.qr)
buf[0] |= 0x80;
c = (unsigned char)a->opts.opcode;
buf[0] |= c << 3;
if(a->opts.aa)
buf[0] |= 0x04;
if(a->opts.tc)
buf[0] |= 0x02;
if(a->opts.rd)
buf[0] |= 0x01;
if(a->opts.ra)
buf[1] |= 0x80;
c = (unsigned char)a->opts.z;
buf[1] |= c << 4;
c = (unsigned char)a->opts.rcode;
buf[1] |= c;
buf += 2;
short2net((unsigned short int)a->questions->count, &buf);
short2net((unsigned short int)a->answerRecords->count, &buf);
short2net((unsigned short int)a->authorityRecords->count, &buf);
short2net((unsigned short int)a->additionalRecords->count, &buf);
// append sections
lookup = jdns_list_new();
lookup->autoDelete = 1;
if(!append_qsection(a->questions, buf - block, last - buf, &buf, lookup))
goto error;
if(!append_rrsection(a->answerRecords, buf - block, last - buf, &buf, lookup))
goto error;
if(!append_rrsection(a->authorityRecords, buf - block, last - buf, &buf, lookup))
goto error;
if(!append_rrsection(a->additionalRecords, buf - block, last - buf, &buf, lookup))
goto error;
// done with all sections
jdns_list_delete(lookup);
// condense
size = buf - block;
block = (unsigned char *)jdns_realloc(block, size);
// finalize
a->qdcount = a->questions->count;
a->ancount = a->answerRecords->count;
a->nscount = a->authorityRecords->count;
a->arcount = a->additionalRecords->count;
a->raw_data = block;
a->raw_size = size;
return 1;
error:
jdns_list_delete(lookup);
if(block)
jdns_free(block);
return 0;
}
// lookup list is made of jdns_packet_labels
static int writelabel(const jdns_string_t *name, int at, int left, unsigned char **bufp, jdns_list_t *lookup)
{
unsigned char label[MAX_LABEL_LENGTH];
int n, i, len;
unsigned char *l;
unsigned char *ref;
int refsize;
len = name_to_label(name, label);
if(len == -1)
return 0;
ref = *bufp - at;
refsize = at + left;
for(n = 0; label[n]; n += label[n] + 1)
{
for(i = 0; i < lookup->count; ++i)
{
jdns_packet_label_t *pl = (jdns_packet_label_t *)lookup->item[i];
if(matchlabel(label + n, len - n, pl->value->data, pl->value->size, ref, refsize, 8, 8))
{
// set up a pointer right here, overwriting
// the length byte and the first content
// byte of this section within 'label'.
// this is safe, because the length value
// will always be greater than zero,
// ensuring we have two bytes available to
// use.
l = label + n;
short2net((unsigned short int)pl->offset, &l);
label[n] |= 0xc0;
len = n + 2; // cut things short
break;
}
}
if(label[n] & 0xc0) // double loop, so break again
break;
}
if(left < len)
return 0;
// copy into buffer, point there now
memcpy(*bufp, label, len);
l = *bufp;
*bufp += len;
// for each new label, store its location for future compression
for(n = 0; l[n]; n += l[n] + 1)
{
jdns_string_t *str;
jdns_packet_label_t *pl;
if(l[n] & 0xc0)
break;
pl = jdns_packet_label_new();
str = jdns_string_new();
jdns_string_set(str, l + n, len - n);
pl->offset = l + n - ref;
pl->value = str;
jdns_list_insert(lookup, pl, -1);
}
return 1;
}
