forked from DNSPod/dnspod-sr
/
dns.c
1376 lines (1292 loc) · 36.5 KB
/
dns.c
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/* Copyright (c) 2006-2012, DNSPod Inc.
* All rights reserved.
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
* ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
* The views and conclusions contained in the software and documentation are those
* of the authors and should not be interpreted as representing official policies,
* either expressed or implied, of the FreeBSD Project.
*/
#include "dns.h"
//types we support at the moment
const enum rrtype support_type[] =
{ A, NS, CNAME, SOA, MX, TXT, AAAA, SRV };
////////////////////////////////////////////////////////////////////
//'a','.','b','.','c','.',0
// 1 ,'a','1','b', 1, 'c',0
uchar *
str_to_len_label(uchar * domain, int len)
{
uchar *ptr, l = 0;
int i;
//we need a extran byte to put len.
if (domain[len - 1] != 0 || domain[len - 2] != '.')
return NULL;
for (i = len - 2; i > 0; i--) {
domain[i] = domain[i - 1];
l++;
if (domain[i] == '.') {
domain[i] = l - 1;
l = 0;
}
}
domain[0] = l;
return domain;
}
//we do not support type DS, KEY etc.
int
check_support_type(ushort type)
{
int i, num = sizeof(support_type) / sizeof(enum rrtype);
for (i = 0; i < num; i++)
if (type == support_type[i])
return 0;
return -1;
}
//make import info into struct baseinfo
struct baseinfo
passer_dns_data(struct sockinfo *si)
{
uchar *buf = si->buf;
int num;
int i = 0, len = sizeof(struct sockaddr_in);
int dlen = 0, seg = 0;
struct baseinfo bi;
uchar *tail = NULL, *ptrs[MAX_NS_LVL] = { 0 }, *domain = NULL;
ushort offset;
dnsheader *hdr = (dnsheader *) buf;
bi.err = 1;
num = ntohs(hdr->qdcount);
if (num != 1)
return bi;
num = ntohs(hdr->ancount);
if (num != 0)
return bi;
num = ntohs(hdr->nscount);
if (num != 0)
return bi;
num = ntohs(hdr->arcount);
if (num > 1) //edns makes ar==1
return bi;
bi.id = hdr->id;
//if(check_client_addr() < 0)
//return bi;
dlen = check_dns_name(buf + sizeof(dnsheader), &seg);
if (dlen < 0)
return bi;
bi.dlen = dlen;
tail = bi.origindomain = buf + sizeof(dnsheader);
tail += dlen;
bi.type = ntohs(*(ushort *) tail);
if (check_support_type(bi.type) == 0)
bi.err = 0;
return bi;
}
//we'd better send the right domain and id
int
send_tc_to_client(uchar * td, struct sockinfo *si, ushort cid)
{
uchar buffer[255] = { 0 }, *itor = buffer;
dnsheader *hdr = (dnsheader *) itor;
qdns *qd = NULL;
int dlen = -1;
if (td == NULL || si == NULL)
return -1;
hdr->id = cid;
hdr->flags = 0;
hdr->flags = SET_QR_R(hdr->flags);
hdr->flags = SET_RA(hdr->flags);
hdr->flags = SET_TC(hdr->flags);
hdr->flags = htons(hdr->flags);
hdr->qdcount = htons(1);
hdr->ancount = hdr->nscount = hdr->arcount = htons(0);
itor += sizeof(dnsheader);
dlen = strlen(td + 1);
memcpy(itor, td + 1, dlen + 1);
itor = itor + dlen + 1;
qd = (qdns *) itor;
qd->type = htons(td[0]);
qd->dclass = htons(CLASS_IN);
itor += sizeof(qdns);
si->buf = buffer;
si->buflen = itor - buffer;
udp_write_info(si, 0);
return 0;
}
//transfrom domain from lenlabel format to string
int
get_domain_from_msg(uchar * itor, uchar * hdr, uchar * to)
{
uchar len, *tmp = NULL;
ushort offset = 0;
len = itor[0];
int dlen = 0, tmplen = 0;
int hasptr = 0, infinite = 20;
offset = htons((ushort) * (ushort *) itor);
while ((len != 0) && (infinite--)) {
if (IS_PTR(offset)) {
itor = hdr + GET_OFFSET(offset);
if (hasptr == 0) {
dlen = 2;
if (tmplen != 0)
dlen += tmplen;
}
hasptr = 1;
}
to[0] = itor[0];
tmplen += 1; //len
tmplen += to[0]; //label
if (to[0] > 64)
return -1;
to++;
memcpy(to, itor + 1, itor[0]);
to += itor[0];
itor = itor + itor[0] + 1;
len = itor[0];
offset = htons((ushort) * (ushort *) itor);
}
if (infinite <= 0) //loops error
return -1;
to[0] = 0;
to++;
tmplen++;
if (dlen == 0)
dlen = tmplen; //root len is 1
if (dlen > MAX_DOMAIN_LEN)
return -1;
return dlen;
}
//malloced here
//tn will be free by author before add_to_quizzer
//and data will be free by release_qoutinfo
int
insert_into_ttltree(struct rbtree *rbt, uchar * td, uint ttl)
{
struct rbnode node = { 0 };
struct ttlnode *tn = NULL;
int len = 0;
len = strlen(td) + 1;
//printf("ttl is %u\n",ttl);
if ((tn = malloc(sizeof(struct ttlnode))) == NULL)
return -1;
if ((tn->data = malloc(len)) == NULL) {
free(tn);
return -1;
}
tn->dlen = len;
tn->exp = ttl;
memcpy(tn->data, td, len);
node.key = tn;
insert_node(rbt, &node);
return 0;
}
uint
random_ttl(uint ttl)
{
uint tmp, ret = ttl % 7;
ttl = ttl + ret * 3;
if (ttl > MAX_TTL)
ttl = MAX_TTL - (ttl % MAX_TTL);
return ttl;
}
int
is_parent(uchar * parent, uchar * son)
{
int sp, ss, x;
sp = strlen(parent);
ss = strlen(son);
if (ss < sp)
return -1;
x = ss - sp;
son = son + x;
if (strcmp(parent, son) == 0)
return 0;
return -1;
}
//if we query abc.com
//the auth server returned
//bbc.com NS ns1.sina.com
//we should reject this
int
check_dms(uchar * ck, uchar * dms, int num)
{
return 0;
}
//when we insert "ttl expired" in the rbtree
//if A or CNAME or MX or TXT or ... 's ttl is small, then we don't need to insert
//NS's "ttl expired" element, we update the record at the same time when we
//update A or CNAME Or MX or TXT or....
//if NS's ttl is small than A or CNAME or MX or TXT or ...
//we update it when update A or CNAME or MX or TXT, or when some query some domain's NS
//in brief, we insert ANSWER section into ttl tree only.
uchar *
process_rdata(struct hlpp * hlp, uchar * label, int n)
{
uchar buffer[65535] = { 0 };
ushort type = 0, class, lth, offset;
uint ttl = 0, tmpttl, tx;
int i, dlen, bidx = 0, ret;
int *stype = hlp->stype;
struct htable *ds = hlp->ds;
struct rbtree *rbt = hlp->rbt;
uchar *hdr = hlp->buf;
int mlen = hlp->datalen;
struct mvalue *mv = (struct mvalue *) buffer;
uchar tmpdomain[512] = { 0 }, dm[512] = {
0}, *itor = NULL;
ushort tmptype = 0;
int tag;
itor = buffer + sizeof(struct mvalue);
tx = global_now; ///
//if(hlp->section != AN_SECTION) //see header comments.
//rbt = NULL;
for (i = 0; i < n; i++) {
dlen = get_domain_from_msg(label, hdr, tmpdomain);
if (dm[1] == 0 && dm[2] == 0) //first time
{
memcpy(dm + 1, tmpdomain, strlen(tmpdomain) + 1);
if (check_dms(dm + 1, hlp->dms, hlp->dmsidx) < 0)
return NULL;
}
if (dlen < 0)
return NULL;
label += dlen;
if (get_dns_info(label, &tmptype, &class, &ttl, <h) < 0)
return NULL;
if (ttl < MIN_TTL)
ttl = MIN_TTL;
ttl = random_ttl(ttl + n);
label += 10; // 2type,2class,4ttl,2lth
if (tmptype == SOA || tmptype == CNAME)
*stype = tmptype;
if (type == 0) //first time
type = tmptype;
if (ttl > MAX_TTL)
ttl = MAX_TTL;
if (tmpttl == 0) //first time
tmpttl = ttl;
if ((strcmp(tmpdomain, dm + 1) != 0) || (type != tmptype)) {
if (check_dms(dm, hlp->dms, hlp->dmsidx) < 0)
return NULL;
dm[0] = type;
mv->ttl = random_ttl(tmpttl + i + (tx % 5)) + tx;
mv->hits = 0;
mv->seg = 0;
//23com0
if (dm[dm[1] + 2] != 0) //not top level domain
insert_kv_mem(rbt, ds, dm, buffer,
mv->len + sizeof(struct mvalue));
type = tmptype;
memcpy(dm + 1, tmpdomain, strlen(tmpdomain) + 1);
mv->len = mv->ttl = mv->num = mv->hits = 0;
itor = buffer + sizeof(struct mvalue);
}
ret = fill_rrset_in_buffer(itor, label, hdr, lth, type, hlp);
if (ret > 0) {
itor += ret; //in dns msg
mv->len += ret; //in memory
mv->num++;
}
tmpttl = ttl;
label += lth;
if ((label < hdr) || (label > (hdr + mlen)))
return NULL;
}
if (mv->num > 0) {
dm[0] = type;
mv->ttl = random_ttl(tmpttl + i + (tx % 5)) + tx;
mv->hits = 0;
mv->seg = 0;
if (dm[dm[1] + 2] != 0) //not top level domain
insert_kv_mem(rbt, ds, dm, buffer,
mv->len + sizeof(struct mvalue));
}
return label;
}
int
check_domain_mask(uchar * domain, uchar * origin)
{
int len = 0;
len = strlen(origin);
return strncmp(origin, domain, len + 1);
}
int
get_dns_info(uchar * label, ushort * tp, ushort * cls, uint * ttl,
ushort * lth)
{
ushort *us = NULL;
uint *ui = NULL;
us = (ushort *) label;
*tp = ntohs(*us); //type
if (*tp > 254) {
printf("type is %u\n", *tp);
return -1;
}
label += sizeof(ushort);
us = (ushort *) label;
*cls = ntohs(*us);
if (*cls != CLASS_IN)
return -1;
label += sizeof(ushort);
ui = (uint *) label;
*ttl = ntohl(*ui);
label += sizeof(uint);
us = (ushort *) label;
*lth = ntohs(*us);
return 0;
}
int
check_dns_name(uchar * domain, int *seg)
{
uchar len = domain[0], i;
int tlen = 0, sg = 0; //extra total len and type
domain++;
while (len != 0) {
if (len > 63)
return -1;
for (i = 0; i < len; i++) //num a-z A-Z -
if (!
((domain[i] >= '0' && domain[i] <= '9')
|| (domain[i] >= 'a' && domain[i] <= 'z')
|| (domain[i] >= 'A' && domain[i] <= 'Z')
|| domain[i] == '-'))
return -1;
sg++;
tlen = tlen + 1 + len;
domain = domain + len;
len = domain[0];
domain++;
}
tlen++; //for end 0
if (tlen > 255)
return -1;
*seg = sg;
return tlen;
}
int
make_type_domain(uchar * domain, int dlen, int type, uchar * buffer)
{
if (buffer == NULL || domain == NULL)
return -1;
buffer[0] = type;
memcpy(buffer + 1, domain, dlen + 1);
return 0;
}
int
check_memcpy(uchar * to, uchar * from, int vlen)
{
int i;
for (i = 0; i < vlen; i++)
if (to[i] != from[i])
return -1;
return 0;
}
//k and v both are in stack
//k td
//v mvalue.data
int
insert_kv_mem(struct rbtree *rbt, struct htable *ds, uchar * k, uchar * v,
int vlen)
{
uchar *val = NULL;
struct mvalue *mv = NULL, tmp;
int ret = -1;
struct rbnode *pn = NULL;
struct ttlnode tn = { 0 };
if (vlen < 0 || vlen > MAX_RECORD_SIZE)
return -1;
hashval_t hash = nocase_char_hash_function(k);
hash = get_pre_mem_hash(k);
val = malloc(vlen);
if (val == NULL)
return -1;
memcpy(val, v, vlen);
mv = (struct mvalue *) v;
ret = htable_insert(ds + hash, k, val, 1, &tmp); //mem, replace
if (ret == 2)
free(val);
if (mv->ttl == (MAX_TTL + 1)) //never expired
return 0;
if (rbt == NULL)
return 0;
//data exists in htable, delete it in ttl tree, then insert
pthread_mutex_lock(&rbt->lock);
if (ret != 0) {
tn.dlen = strlen(k) + 1;
//tmp get old data
tn.exp = tmp.ttl;
tn.data = k;
pn = find_node(rbt, &tn);
//if update, we had delete tn in rbt
//else update tn in rbt
if (pn != NULL)
delete_node(rbt, pn);
}
ret = insert_into_ttltree(rbt, k, mv->ttl); //ttl expired tree
pthread_mutex_unlock(&rbt->lock);
return 0;
}
////////////////////////////////////////////////////////////////////
int
get_level(uchar * itor)
{
int lvl = 0;
uchar len = itor[0];
while (len != 0) {
lvl++;
itor += itor[0] + 1;
len = itor[0];
if (len > 63)
return -1;
}
return lvl;
}
uchar *
fill_all_records_in_msg(struct hlpc * h, struct hlpf * hf, int idx)
{
int datalen, step = 0;
uint16_t txtlen;
uchar *tmp = NULL, *to = hf->to, *from = hf->from;
struct fillmsg *fm = (struct fillmsg *) (hf->to);
fm->type = htons(hf->type);
fm->dclass = htons(CLASS_IN);
fm->ttl = htonl(hf->ttl - global_now);
if (hf->ttl == MAX_TTL + 1)
fm->ttl = htonl(hf->ttl - 1);
to = to + sizeof(struct fillmsg);
if (hf->type == A)
step = 4;
if (hf->type == AAAA)
step = 16;
switch (hf->type) // no soa
{
case A: //idx not used
case AAAA:
fm->len = htons(step);
memcpy(to, from, step);
to = to + step; //data
break;
case CNAME:
case NS:
idx++;
h[idx].name = from;
h[idx].off = to - hf->hdr;
h[idx].ref = -1;
h[idx].level = get_level(h[idx].name);
tmp = fill_name_in_msg(h, to, idx);
fm->len = htons(tmp - to);
to = tmp;
break;
case MX:
memcpy(to, from, sizeof(uint16_t)); //ref
from += sizeof(uint16_t); //2
to += sizeof(uint16_t);
idx++;
h[idx].name = from;
h[idx].off = to - hf->hdr;
h[idx].ref = -1;
h[idx].level = get_level(h[idx].name);
tmp = fill_name_in_msg(h, to, idx);
fm->len = htons(tmp - to + sizeof(uint16_t));
to = tmp;
break;
case TXT:
txtlen = *(uint16_t *) from;
from += sizeof(uint16_t); //len
memcpy(to, from, txtlen);
fm->len = htons(txtlen);
to += txtlen;
break;
case SRV:
memcpy(to, from, sizeof(uint16_t) * 3);
from += sizeof(uint16_t) * 3;
to = to + sizeof(uint16_t) * 3;
idx++;
h[idx].name = from;
h[idx].off = to - hf->hdr;
h[idx].ref = -1;
h[idx].level = get_level(h[idx].name);
tmp = fill_name_in_msg(h, to, idx);
fm->len = htons(tmp - to + sizeof(uint16_t) * 3);
to = tmp;
break;
default:
break;
}
return to;
}
//return the match length in the end of two strings.
//NOT include the end "."
int
reverse_compare(uchar * from, int flen, uchar * to, int tolen)
{
uchar fi, ti, rec = 0;
int match = 0;
flen -= 2; //1 for strlen + 1, 1 for array in c
tolen -= 2;
fi = from[flen];
ti = to[tolen];
while (flen && tolen) {
if (fi != ti)
break;
rec++;
if (fi == (rec - 1)) //not include len itself
{
match++;
rec = 0;
}
fi = from[--flen];
ti = to[--tolen];
}
return match;
}
//imxg3.douban.com imxg3.douban.com.cdn20.com.
uchar *
fill_name_in_msg(struct hlpc * h, uchar * to, int idx)
{
int i, mm = 0, m = 0, len, fill = 0, ml = 0, jump = 0, off = 0;
const ushort base = 0xc000;
uchar *itor = h[idx].name, *dn = NULL;
if (idx == 0) {
*(ushort *) to = htons(h[0].off + base);
to += sizeof(ushort);
return to;
}
len = strlen(h[idx].name);
for (i = idx - 1; i >= 0; i--) {
m = reverse_compare(h[i].name, strlen(h[i].name) + 1, h[idx].name,
len + 1);
if (m > h[i].mt) {
h[idx].mt = m; //max match
h[idx].ref = i;
}
}
if (mm > len)
return NULL;
if (h[idx].mt >= 0)
fill = h[idx].level - h[idx].mt;
else
fill = h[idx].level;
for (i = 0; i < fill; i++) {
memcpy(to, itor, itor[0] + 1); //len.label
to = to + itor[0] + 1;
itor = itor + itor[0] + 1;
}
len = 0;
if (h[idx].ref >= 0) {
dn = h[h[idx].ref].name;
jump = h[h[idx].ref].level - h[idx].mt;
for (i = 0; i < jump; i++) {
len += dn[0] + 1;
dn += dn[0] + 1;
}
off = h[h[idx].ref].off + len;
*(ushort *) to = htons(off + base);
to += 2;
} else {
to[0] = 0; //no compression
to++;
}
return to;
}
//jump from author.c
uchar *
fill_rrset_in_msg(struct hlpc * h, uchar * from, uchar * to, int n,
uchar * hdr, uint16_t * ttloff)
{
uchar type;
type = from[0];
int i, step = 0, ttloffidx;
uint16_t txtlen = 0;
struct hlpf hf;
struct mvalue *mv = NULL;
ttloffidx = ttloff[0]; //must be 0
from++; //type
mv = (struct mvalue *) from;
from = from + sizeof(struct mvalue);
hf.hdr = hdr;
hf.ttl = mv->ttl;
hf.type = type;
if (type == A)
step = 4;
if (type == AAAA)
step = 16;
switch (type) //7
{
case A:
case AAAA:
for (i = 0; i < mv->num; i++) {
to = fill_name_in_msg(h, to, n);
hf.from = from;
hf.to = to;
//jump type and dclass
//then we get ttl's position
//plus hdr we get it's offset
//only for A record
if (type == A) {
//ttloff[0] idx
//+1, jump it
ttloff[ttloff[0] + 1] =
to + sizeof(uint16_t) + sizeof(uint16_t) - hdr;
ttloff[0]++;
}
to = fill_all_records_in_msg(h, &hf, n);
from += step;
}
return to;
break;
case CNAME: // cname must has 1 record
to = fill_name_in_msg(h, to, n);
hf.from = from;
hf.to = to;
to = fill_all_records_in_msg(h, &hf, n);
return to;
break;
case NS:
for (i = 0; i < mv->num; i++) {
to = fill_name_in_msg(h, to, n);
hf.from = from;
hf.to = to;
to = fill_all_records_in_msg(h, &hf, n);
from += strlen(from) + 1;
}
return to;
break;
case MX:
for (i = 0; i < mv->num; i++) {
to = fill_name_in_msg(h, to, n);
hf.from = from;
hf.to = to;
to = fill_all_records_in_msg(h, &hf, n + i);
from += sizeof(uint16_t); //jump ref
from += strlen(from) + 1; //jump name and tail 0
}
return to;
break;
case TXT:
for (i = 0; i < mv->num; i++) {
to = fill_name_in_msg(h, to, n);
hf.from = from;
hf.to = to;
to = fill_all_records_in_msg(h, &hf, n);
txtlen = *(uint16_t *) from;
from = from + txtlen + sizeof(uint16_t);
}
return to;
break;
case SRV:
for (i = 0; i < mv->num; i++) {
to = fill_name_in_msg(h, to, n);
hf.from = from;
hf.to = to;
to = fill_all_records_in_msg(h, &hf, n);
from += sizeof(uint16_t) * 3; //pri wei port
from += strlen(from) + 1; //target
}
return to;
break;
default:
printf("not support or error in fill msg\n");
break;
}
return NULL;
}
uchar *
fill_header_in_msg(struct setheader * sh)
{
uchar llen = 0;
uchar *itor = sh->itor;
dnsheader *hdr = (dnsheader *) (sh->itor);
qdns *qd;
int i, dlen;
hdr->id = sh->id;
hdr->flags = 0;
hdr->flags = SET_QR_R(hdr->flags);
hdr->flags = SET_RA(hdr->flags);
//hdr->flags = SET_ERROR(hdr->flags,mf->ed);
hdr->flags = htons(hdr->flags);
hdr->qdcount = htons(1);
hdr->ancount = htons(sh->an);
hdr->nscount = htons(sh->ns);
hdr->arcount = htons(0);
itor += sizeof(dnsheader);
dlen = strlen(sh->od) + 1;
memcpy(itor, sh->od, dlen);
itor = itor + dlen;
qd = (qdns *) itor;
qd->type = htons(sh->type);
qd->dclass = htons(CLASS_IN);
itor += sizeof(qdns);
return itor;
}
int
make_dns_msg_for_new(uchar * itor, ushort msgid, uchar * d, ushort type)
{
uchar *buf = itor;
int need = 0, i, len;
dnsheader *hdr = NULL;
qdns *qd = NULL;
hdr = (dnsheader *) buf;
hdr->id = msgid;
hdr->flags = htons(0x0100); //rd
hdr->qdcount = htons(1);
hdr->ancount = hdr->nscount = hdr->arcount = htons(0);
buf += sizeof(dnsheader);
len = strlen(d) + 1;
memcpy(buf, d, len + 1);
buf += len;
qd = (qdns *) buf;
qd->type = htons(type);
qd->dclass = htons(CLASS_IN);
buf = buf + 4;
return buf - itor; //msg len
}
//a,ns,txt,cname,soa,srv,aaaa,mx
int
fill_rrset_in_buffer(uchar * buffer, uchar * label, uchar * hdr, int lth,
int type, struct hlpp *hlp)
{
int mlen = 0;
uint16_t len = lth;
uchar nsc[512] = { 0 };
struct srv *from, *to;
switch (type) {
case A:
mlen = 4;
memcpy(buffer, label, 4);
break;
case NS:
get_domain_from_msg(label, hdr, nsc);
hlp->dmsidx++;
strcpy(hlp->dms + hlp->dmsidx * DMS_SIZE, nsc);
mlen = strlen(nsc) + 1;
memcpy(buffer, nsc, mlen);
break;
case CNAME:
get_domain_from_msg(label, hdr, nsc);
hlp->dmsidx++;
strcpy(hlp->dms + hlp->dmsidx * DMS_SIZE, nsc);
mlen = strlen(nsc) + 1;
memcpy(buffer, nsc, mlen);
break;
case SOA: //do nothing
mlen = 0;
break;
case AAAA:
mlen = 16;
memcpy(buffer, label, 16);
break;
case MX:
memcpy(buffer, label, 2); //reference value
label += 2; //16bits
buffer += 2;
get_domain_from_msg(label, hdr, nsc);
hlp->dmsidx++;
strcpy(hlp->dms + hlp->dmsidx * DMS_SIZE, nsc);
mlen = strlen(nsc) + 1;
memcpy(buffer, nsc, mlen);
mlen += 2;
break;
case SRV:
from = (struct srv *) label;
to = (struct srv *) buffer;
to->pri = from->pri; //net endian
to->wei = from->wei;
to->port = from->port;
buffer += sizeof(uint16_t) * 3;
label += sizeof(uint16_t) * 3;
get_domain_from_msg(label, hdr, nsc);
mlen = strlen(nsc) + 1;
memcpy(buffer, nsc, mlen);
mlen += sizeof(uint16_t) * 3;
break;
case TXT: //the only case that lth used
memcpy(buffer, &len, sizeof(uint16_t)); //uint16_t
buffer += sizeof(uint16_t);
memcpy(buffer, label, lth);
mlen = lth + sizeof(uint16_t);
break;
default:
return -1;
}
return mlen;
}
//-1 error
//1 tc
//0 normal
//2 retry
int
check_an_msg(ushort flag, uchar * domain, int *bk)
{
uint get = 0;
flag = ntohs(flag);
//printf("flag is 0x%x\n",flag);
get = GET_QR(flag);
if (get == QR_Q) //query
{
printf("answer set Q sign\n");
return -1;
}
get = GET_OPCODE(flag); //ignore.
get = GET_AA(flag); //ignore
get = GET_TC(flag);
if (get == 1)
return 1; //tc
get = GET_RD(flag); //ignore
get = GET_ERROR(flag);
if ((get != 0) && (get != NAME_ERROR)) //soa
{
switch (get) {
case SERVER_FAIL:
//printf("2server fail\n");
break;
//case NAME_ERROR: SOA
//*bk = 1;
//printf("3name error\n");
//break;
case FORMAT_ERROR:
//*bk = 1;
//printf("1format error\n");
break;
case NOT_IMPL:
//printf("4not implation\n");
break;
case REFUSED:
//printf("5server refused\n");
break;
}
return 2;
}
return 0;
}
int
check_out_msg(ushort cid, uchar * buf, int len)
{
dnsheader *hdr = (dnsheader *) buf;
hdr->id = cid;
hdr->flags = 0;
hdr->flags = htons(SET_QR_R(hdr->flags));
return 0;
}
int
check_td(uchar * td)
{
uchar type = td[0];
uchar *itor = td + 1;
uchar len = itor[0];
if ((type != A) && (type != NS) && (type != CNAME))
return -1;
while (len != 0) {
if (len > 50)
return -1;
itor = itor + len + 1;
len = itor[0];
}
return 0;
}
//if ns is domain's child or child's child or...
//domain and ns are td format
//type.domain
//002,005,b,a,i,d,u,003,c,o,m
//003,n,s,'4',005,b,a,i,d,u,003,c,o,m
int
is_glue(uchar * domain, uchar * ns)
{
uchar d, n;
int dlen, nlen;
dlen = strlen(domain);
nlen = strlen(ns);
dlen--;
nlen--;
if (dlen >= nlen)
return 0;
d = domain[dlen];
n = ns[nlen];
while (d == n) {
dlen--;
nlen--;
if (dlen == 0)
return 1;
d = domain[dlen];
n = ns[nlen];
}
return 0;
}
//First ensure the search name, if it has a cname, search the cname
//If we find it in fwd table, return the ip length, it's > 0
//Here we dont care the cname in fwd table, if somebody want to do this
//Add the main domain in fwd table
int