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#include <netdb.h>
#include <limits.h>
#include <string.h>
#include <stdio.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
int __dns_parse(const unsigned char *, int, int (*)(void *, int, const void *, int, const void *), void *);
int __dn_expand(const unsigned char *, const unsigned char *, const unsigned char *, char *, int);
int __res_mkquery(int, const char *, int, int, const unsigned char *, int, const unsigned char*, unsigned char *, int);
int __res_send(const unsigned char *, int, unsigned char *, int);
#define PTR_MAX (64 + sizeof ".in-addr.arpa")
#define RR_PTR 12
static void mkptr4(char *s, const unsigned char *ip)
{
sprintf(s, "%d.%d.%d.%d.in-addr.arpa",
ip[3], ip[2], ip[1], ip[0]);
}
static void mkptr6(char *s, const unsigned char *ip)
{
static const char xdigits[] = "0123456789abcdef";
int i;
for (i=15; i>=0; i--) {
*s++ = xdigits[ip[i]&15]; *s++ = '.';
*s++ = xdigits[ip[i]>>4]; *s++ = '.';
}
strcpy(s, "ip6.arpa");
}
static int dns_parse_callback(void *c, int rr, const void *data, int len, const void *packet)
{
char tmp[256];
if (rr != RR_PTR) return 0;
if (__dn_expand(packet, (const unsigned char *)packet + 512,
data, tmp, sizeof tmp) > 0)
strcpy(c, tmp);
return 0;
}
int getnameinfo(const struct sockaddr *restrict sa, socklen_t sl,
char *restrict node, socklen_t nodelen,
char *restrict serv, socklen_t servlen,
int flags)
{
char ptr[PTR_MAX];
char buf[256];
int af = sa->sa_family;
unsigned char *a;
switch (af) {
case AF_INET:
a = (void *)&((struct sockaddr_in *)sa)->sin_addr;
if (sl != sizeof(struct sockaddr_in)) return EAI_FAMILY;
mkptr4(ptr, a);
break;
case AF_INET6:
a = (void *)&((struct sockaddr_in6 *)sa)->sin6_addr;
if (sl != sizeof(struct sockaddr_in6)) return EAI_FAMILY;
if (memcmp(a, "\0\0\0\0\0\0\0\0\0\0\xff\xff", 12))
mkptr6(ptr, a);
else
mkptr4(ptr, a+12);
break;
default:
return EAI_FAMILY;
}
if (node && nodelen) {
buf[0] = 0;
if (!(flags & NI_NUMERICHOST)) {
unsigned char query[18+PTR_MAX], reply[512];
int qlen = __res_mkquery(0, ptr, 1, RR_PTR,
0, 0, 0, query, sizeof query);
int rlen = __res_send(query, qlen, reply, sizeof reply);
buf[0] = 0;
if (rlen > 0)
__dns_parse(reply, rlen, dns_parse_callback, buf);
}
if (!*buf) {
if (flags & NI_NAMEREQD) return EAI_NONAME;
inet_ntop(af, a, buf, sizeof buf);
}
if (strlen(buf) >= nodelen) return EAI_OVERFLOW;
strcpy(node, buf);
}
if (serv && servlen) {
if (snprintf(buf, sizeof buf, "%d",
ntohs(((struct sockaddr_in *)sa)->sin_port))>=servlen)
return EAI_OVERFLOW;
strcpy(serv, buf);
}
return 0;
}
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