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