int dns_ip4_packet(stralloc *out,const char *buf,unsigned int len)
{
unsigned int pos;
char header[12];
uint16 numanswers;
uint16 datalen;
if (!stralloc_copys(out,"")) return -1;
pos = dns_packet_copy(buf,len,0,header,12); if (!pos) return -1;
uint16_unpack_big(header + 6,&numanswers);
pos = dns_packet_skipname(buf,len,pos); if (!pos) return -1;
pos += 4;
while (numanswers--) {
pos = dns_packet_skipname(buf,len,pos); if (!pos) return -1;
pos = dns_packet_copy(buf,len,pos,header,10); if (!pos) return -1;
uint16_unpack_big(header + 8,&datalen);
if (byte_equal(header,2,DNS_T_A))
if (byte_equal(header + 2,2,DNS_C_IN))
if (datalen == 4) {
if (!dns_packet_copy(buf,len,pos,header,4)) return -1;
if (!stralloc_catb(out,header,4)) return -1;
}
pos += datalen;
}
dns_sortip(out->s,out->len);
return 0;
}
int dns_mx_packet(stralloc *out,const char *buf,unsigned int len)
{
unsigned int pos;
char header[12];
char pref[2];
uint16 numanswers;
uint16 datalen;
if (!stralloc_copys(out,"")) return -1;
pos = dns_packet_copy(buf,len,0,header,12); if (!pos) return -1;
uint16_unpack_big(header + 6,&numanswers);
pos = dns_packet_skipname(buf,len,pos); if (!pos) return -1;
pos += 4;
while (numanswers--) {
pos = dns_packet_skipname(buf,len,pos); if (!pos) return -1;
pos = dns_packet_copy(buf,len,pos,header,10); if (!pos) return -1;
uint16_unpack_big(header + 8,&datalen);
if (byte_equal(header,2,DNS_T_MX))
if (byte_equal(header + 2,2,DNS_C_IN)) {
if (!dns_packet_copy(buf,len,pos,pref,2)) return -1;
if (!dns_packet_getname(buf,len,pos + 2,&q)) return -1;
if (!stralloc_catb(out,pref,2)) return -1;
if (!dns_domain_todot_cat(out,q)) return -1;
if (!stralloc_0(out)) return -1;
}
pos += datalen;
}
return 0;
}
int dns_txt_packet(stralloc *out,const char *buf,unsigned int len)
{
unsigned int pos;
char header[12];
uint16 numanswers;
uint16 datalen;
char ch;
unsigned int txtlen;
int i;
if (!stralloc_copys(out,"")) return -1;
pos = dns_packet_copy(buf,len,0,header,12); if (!pos) return -1;
uint16_unpack_big(header + 6,&numanswers);
pos = dns_packet_skipname(buf,len,pos); if (!pos) return -1;
pos += 4;
while (numanswers--) {
pos = dns_packet_skipname(buf,len,pos); if (!pos) return -1;
pos = dns_packet_copy(buf,len,pos,header,10); if (!pos) return -1;
uint16_unpack_big(header + 8,&datalen);
if (byte_equal(header,2,DNS_T_TXT))
if (byte_equal(header + 2,2,DNS_C_IN)) {
if (pos + datalen > len) return -1;
txtlen = 0;
for (i = 0;i < datalen;++i) {
ch = buf[pos + i];
if (!txtlen)
txtlen = (unsigned char) ch;
else {
--txtlen;
if (ch < 32) ch = '?';
if (ch > 126) ch = '?';
if (!stralloc_append(out,&ch)) return -1;
}
}
}
pos += datalen;
}
return 0;
}
static int want(const char *owner,const char type[2])
{
unsigned int pos;
static char *d;
char x[10];
uint16 datalen;
pos = dns_packet_skipname(response,response_len,12); if (!pos) return 0;
pos += 4;
while (pos < response_len) {
pos = dns_packet_getname(response,response_len,pos,&d); if (!pos) return 0;
pos = dns_packet_copy(response,response_len,pos,x,10); if (!pos) return 0;
if (dns_domain_equal(d,owner))
if (byte_equal(type,2,x))
return 0;
uint16_unpack_big(x + 8,&datalen);
pos += datalen;
}
return 1;
}
static int doit(char *q,char qtype[2])
{
unsigned int bpos;
unsigned int anpos;
unsigned int aupos;
unsigned int arpos;
char *control;
char *wild;
int flaggavesoa;
int flagfound;
int r;
int flagns;
int flagauthoritative;
char x[20];
uint16 u16;
char addr[8][4];
int addrnum;
uint32 addrttl;
int i;
anpos = response_len;
control = q;
for (;;) {
flagns = 0;
flagauthoritative = 0;
cdb_findstart(&c);
while (r = find(control,0)) {
if (r == -1) return 0;
if (byte_equal(type,2,DNS_T_SOA)) flagauthoritative = 1;
if (byte_equal(type,2,DNS_T_NS)) flagns = 1;
}
if (flagns) break;
if (!*control) return 0; /* q is not within our bailiwick */
control += *control;
control += 1;
}
if (!flagauthoritative) {
response[2] &= ~4;
goto AUTHORITY; /* q is in a child zone */
}
flaggavesoa = 0;
flagfound = 0;
wild = q;
for (;;) {
addrnum = 0;
addrttl = 0;
cdb_findstart(&c);
while (r = find(wild,wild != q)) {
if (r == -1) return 0;
flagfound = 1;
if (flaggavesoa && byte_equal(type,2,DNS_T_SOA)) continue;
if (byte_diff(type,2,qtype) && byte_diff(qtype,2,DNS_T_ANY) && byte_diff(type,2,DNS_T_CNAME)) continue;
if (byte_equal(type,2,DNS_T_A) && (dlen - dpos == 4)) {
addrttl = ttl;
i = dns_random(addrnum + 1);
if (i < 8) {
if ((i < addrnum) && (addrnum < 8))
byte_copy(addr[addrnum],4,addr[i]);
byte_copy(addr[i],4,data + dpos);
}
if (addrnum < 1000000) ++addrnum;
continue;
}
if (!response_rstart(q,type,ttl)) return 0;
if (byte_equal(type,2,DNS_T_NS) || byte_equal(type,2,DNS_T_CNAME) || byte_equal(type,2,DNS_T_PTR)) {
if (!doname()) return 0;
}
else if (byte_equal(type,2,DNS_T_MX)) {
if (!dobytes(2)) return 0;
if (!doname()) return 0;
}
else if (byte_equal(type,2,DNS_T_SOA)) {
if (!doname()) return 0;
if (!doname()) return 0;
if (!dobytes(20)) return 0;
flaggavesoa = 1;
}
else
if (!response_addbytes(data + dpos,dlen - dpos)) return 0;
response_rfinish(RESPONSE_ANSWER);
}
for (i = 0;i < addrnum;++i)
if (i < 8) {
if (!response_rstart(q,DNS_T_A,addrttl)) return 0;
if (!response_addbytes(addr[i],4)) return 0;
response_rfinish(RESPONSE_ANSWER);
}
if (flagfound) break;
if (wild == control) break;
if (!*wild) break; /* impossible */
wild += *wild;
wild += 1;
}
if (!flagfound)
response_nxdomain();
AUTHORITY:
aupos = response_len;
if (flagauthoritative && (aupos == anpos)) {
cdb_findstart(&c);
while (r = find(control,0)) {
if (r == -1) return 0;
if (byte_equal(type,2,DNS_T_SOA)) {
if (!response_rstart(control,DNS_T_SOA,ttl)) return 0;
if (!doname()) return 0;
if (!doname()) return 0;
if (!dobytes(20)) return 0;
response_rfinish(RESPONSE_AUTHORITY);
break;
}
}
}
else
if (want(control,DNS_T_NS)) {
cdb_findstart(&c);
while (r = find(control,0)) {
if (r == -1) return 0;
if (byte_equal(type,2,DNS_T_NS)) {
if (!response_rstart(control,DNS_T_NS,ttl)) return 0;
if (!doname()) return 0;
response_rfinish(RESPONSE_AUTHORITY);
}
}
}
arpos = response_len;
bpos = anpos;
while (bpos < arpos) {
bpos = dns_packet_skipname(response,arpos,bpos); if (!bpos) return 0;
bpos = dns_packet_copy(response,arpos,bpos,x,10); if (!bpos) return 0;
if (byte_equal(x,2,DNS_T_NS) || byte_equal(x,2,DNS_T_MX)) {
if (byte_equal(x,2,DNS_T_NS)) {
if (!dns_packet_getname(response,arpos,bpos,&d1)) return 0;
}
else
if (!dns_packet_getname(response,arpos,bpos + 2,&d1)) return 0;
case_lowerb(d1,dns_domain_length(d1));
if (want(d1,DNS_T_A)) {
cdb_findstart(&c);
while (r = find(d1,0)) {
if (r == -1) return 0;
if (byte_equal(type,2,DNS_T_A)) {
if (!response_rstart(d1,DNS_T_A,ttl)) return 0;
if (!dobytes(4)) return 0;
response_rfinish(RESPONSE_ADDITIONAL);
}
}
}
}
uint16_unpack_big(x + 8,&u16);
bpos += u16;
}
if (flagauthoritative && (response_len > 512)) {
byte_zero(response + RESPONSE_ADDITIONAL,2);
response_len = arpos;
if (response_len > 512) {
byte_zero(response + RESPONSE_AUTHORITY,2);
response_len = aupos;
}
}
return 1;
}
