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#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <stdlib.h>
#include <arpa/inet.h>
#include <sys/poll.h>
#include <unistd.h>
#include <errno.h>
#include <stdio.h>
extern int h_errno;
static char dnspacket[]="\xfe\xfe\001\000\000\001\000\000\000\000\000\000";
extern void __dns_make_fd();
extern int __dns_fd;
extern int __dns_servers;
extern struct sockaddr __dns_server_ips[];
extern void __dns_readstartfiles();
extern int __dns_decodename(unsigned char *packet,int offset,unsigned char *dest,int maxlen);
/* Oh boy, this interface sucks so badly, there are no words for it.
* Not one, not two, but _three_ error signalling methods! (*h_errnop
* nonzero? return value nonzero? *RESULT zero?) The glibc goons
* really outdid themselves with this one. */
int __dns_gethostbyx_r(const char* name, struct hostent* result,
char *buf, size_t buflen,
struct hostent **RESULT, int *h_errnop, int lookfor) {
int names,ips;
unsigned char *cur;
unsigned char *max;
unsigned char packet[512];
__dns_make_fd();
if (lookfor==1) {
result->h_aliases=(char**)(buf+8*4);
result->h_addrtype=AF_INET;
result->h_length=4;
result->h_addr_list=(char**)buf;
} else {
result->h_aliases=(char**)(buf+8*16);
result->h_addrtype=AF_INET6;
result->h_length=16;
result->h_addr_list=(char**)buf;
}
result->h_aliases[0]=0;
cur=buf+16*sizeof(char*);
max=buf+buflen;
names=ips=0;
memmove(packet,dnspacket,12);
*(unsigned short*)packet=rand();
{
unsigned char* x;
const char* y,* tmp;
x=packet+12; y=name;
while (*y) {
while (*y=='.') ++y;
for (tmp=y; *tmp && *tmp!='.'; ++tmp) ;
*x=tmp-y;
if (!(tmp-y)) break;
++x;
if (x>=packet+510-(tmp-y)) { *h_errnop=ERANGE; return 1; }
memmove(x,y,tmp-y);
x+=tmp-y;
if (!*tmp) {
*x=0;
break;
}
y=tmp;
}
*++x= 0; *++x= lookfor; /* A */
*++x= 0; *++x= 1; /* IN */
++x;
{
int i; /* current server */
int j; /* timeout count down */
struct pollfd duh;
i=0; j=30;
__dns_readstartfiles();
duh.fd=__dns_fd;
duh.events=POLLIN;
for (j=30; j>0; --j) {
sendto(__dns_fd,packet,x-packet,0,(struct sockaddr*)&(__dns_server_ips[i]),sizeof(struct sockaddr));
if (++i > __dns_servers) i=0;
if (poll(&duh,1,1) == 1) {
/* read and parse answer */
unsigned char inpkg[1500];
/*int len=*/ read(__dns_fd,inpkg,1500);
#if 0
{
int tft=open("duh",0);
read(tft,inpkg,1500);
close(tft);
}
#endif
/* header, question, answer, authority, additional */
if (inpkg[0]!=packet[0] || inpkg[1]!=packet[1]) continue; /* wrong ID */
if ((inpkg[2]&0xf9) != 0x81) continue; /* not answer */
if ((inpkg[3]&0x0f) != 0) break; /* error */
tmp=inpkg+12;
{
char name[257];
unsigned short q=((unsigned short)inpkg[4]<<8)+inpkg[5];
while (q>0) {
while (*tmp) tmp+=*tmp+1;
tmp+=5;
--q;
}
q=((unsigned short)inpkg[6]<<8)+inpkg[7];
if (q<1) break;
while (q>0) {
int decofs=__dns_decodename(inpkg,tmp-(char*)inpkg,name,256);
if (decofs<0) break;
tmp=inpkg+decofs;
--q;
if (tmp[0]!=0 || tmp[1]!=lookfor || /* TYPE != A */
tmp[2]!=0 || tmp[3]!=1) { /* CLASS != IN */
if (tmp[1]==5) { /* CNAME */
tmp+=10;
decofs=__dns_decodename(inpkg,tmp-(char*)inpkg,name,256);
if (decofs<0) break;
tmp=inpkg+decofs;
} else
break;
continue;
}
tmp+=10; /* skip type, class, TTL and length */
{
int slen;
if (lookfor==1 || lookfor==28) /* A or AAAA*/ {
slen=strlen(name);
if (cur+slen+8+(lookfor==28?12:0)>=max) { *h_errnop=NO_RECOVERY; return 1; }
} else if (lookfor==12) /* PTR */ {
decofs=__dns_decodename(inpkg,tmp-(char*)inpkg,name,256);
if (decofs<0) break;
tmp=inpkg+decofs;
slen=strlen(name);
} else
slen=strlen(name);
strcpy(cur,name);
if (names==0)
result->h_name=cur;
else
result->h_aliases[names-1]=cur;
result->h_aliases[names]=0;
++names;
/* cur+=slen+1; */
cur+=(slen|3)+1;
result->h_addr_list[ips++] = cur;
if (lookfor==1) /* A */ {
*(int*)cur=*(int*)tmp;
cur+=4;
result->h_addr_list[ips]=0;
} else if (lookfor==28) /* AAAA */ {
{
int i;
for (i=0; i<16; ++i) cur[i]=tmp[i];
}
cur+=16;
result->h_addr_list[ips]=0;
}
}
/* puts(name); */
}
}
/* printf("%d answers\n",((unsigned short)inpkg[6]<<8)+inpkg[7]);
printf("ok\n");*/
*h_errnop=0;
*RESULT=result;
return 0;
}
/*kaputt:*/
}
}
}
return 1;
}
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