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#define _GNU_SOURCE
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <inttypes.h>
#include <errno.h>
#include <string.h>
#include <stdlib.h>
int getservbyport_r(int port, const char *prots,
struct servent *se, char *buf, size_t buflen, struct servent **res)
{
int i;
struct sockaddr_in sin = {
.sin_family = AF_INET,
.sin_port = port,
};
if (!prots) {
int r = getservbyport_r(port, "tcp", se, buf, buflen, res);
if (r) r = getservbyport_r(port, "udp", se, buf, buflen, res);
return r;
}
*res = 0;
/* Align buffer */
i = (uintptr_t)buf & sizeof(char *)-1;
if (!i) i = sizeof(char *);
if (buflen <= 3*sizeof(char *)-i)
return ERANGE;
buf += sizeof(char *)-i;
buflen -= sizeof(char *)-i;
if (strcmp(prots, "tcp") && strcmp(prots, "udp")) return EINVAL;
se->s_port = port;
se->s_proto = (char *)prots;
se->s_aliases = (void *)buf;
buf += 2*sizeof(char *);
buflen -= 2*sizeof(char *);
se->s_aliases[1] = 0;
se->s_aliases[0] = se->s_name = buf;
switch (getnameinfo((void *)&sin, sizeof sin, 0, 0, buf, buflen,
strcmp(prots, "udp") ? 0 : NI_DGRAM)) {
case EAI_MEMORY:
case EAI_SYSTEM:
return ENOMEM;
case EAI_OVERFLOW:
return ERANGE;
default:
return ENOENT;
case 0:
break;
}
/* A numeric port string is not a service record. */
if (strtol(buf, 0, 10)==ntohs(port)) return ENOENT;
*res = se;
return 0;
}
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