Rich Felker
565dbee24d
some applications use getservbyport to find port numbers that are not assigned to a service; if getservbyport always succeeds with a numeric string as the result, they fail to find any available ports. POSIX doesn't seem to mandate the behavior one way or another. it specifies an abstract service database, which an implementation could define to include numeric port strings, but it makes more sense to align behavior with traditional implementations. based on patch by A. Wilcox. the original patch only changed getservbyport[_r]. to maintain a consistent view of the "service database", I have also modified getservbyname[_r] to exclude numeric port strings.
56 lines
1.2 KiB
C
56 lines
1.2 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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#include "lookup.h"
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#define ALIGN (sizeof(struct { char a; char *b; }) - sizeof(char *))
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int getservbyname_r(const char *name, 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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struct service servs[MAXSERVS];
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int cnt, proto, align;
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*res = 0;
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/* Don't treat numeric port number strings as service records. */
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char *end = "";
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strtoul(name, &end, 10);
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if (!*end) return ENOENT;
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/* Align buffer */
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align = -(uintptr_t)buf & ALIGN-1;
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if (buflen < 2*sizeof(char *)+align)
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return ERANGE;
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buf += align;
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if (!prots) proto = 0;
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else if (!strcmp(prots, "tcp")) proto = IPPROTO_TCP;
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else if (!strcmp(prots, "udp")) proto = IPPROTO_UDP;
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else return EINVAL;
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cnt = __lookup_serv(servs, name, proto, 0, 0);
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if (cnt<0) switch (cnt) {
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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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}
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se->s_name = (char *)name;
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se->s_aliases = (void *)buf;
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se->s_aliases[0] = se->s_name;
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se->s_aliases[1] = 0;
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se->s_port = htons(servs[0].port);
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se->s_proto = servs[0].proto == IPPROTO_TCP ? "tcp" : "udp";
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*res = se;
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return 0;
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}
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