72 lines
1.5 KiB
C
72 lines
1.5 KiB
C
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#define _GNU_SOURCE
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#include <sys/socket.h>
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#include <netdb.h>
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#include <string.h>
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#include <netinet/in.h>
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#include <errno.h>
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#include <inttypes.h>
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int gethostbyaddr_r(const void *a, socklen_t l, int af,
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struct hostent *h, char *buf, size_t buflen,
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struct hostent **res, int *err)
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{
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union {
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struct sockaddr_in sin;
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struct sockaddr_in6 sin6;
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} sa = { .sin.sin_family = af };
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socklen_t sl = af==AF_INET6 ? sizeof sa.sin6 : sizeof sa.sin;
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int i;
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*res = 0;
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/* Load address argument into sockaddr structure */
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if (af==AF_INET6 && l==16) memcpy(&sa.sin6.sin6_addr, a, 16);
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else if (af==AF_INET && l==4) memcpy(&sa.sin.sin_addr, a, 4);
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else {
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*err = NO_RECOVERY;
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return EINVAL;
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}
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/* Align buffer and check for space for pointers and ip address */
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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 <= 5*sizeof(char *)-i + l) return ERANGE;
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buf += sizeof(char *)-i;
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buflen -= 5*sizeof(char *)-i + l;
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h->h_addr_list = (void *)buf;
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buf += 2*sizeof(char *);
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h->h_aliases = (void *)buf;
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buf += 2*sizeof(char *);
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h->h_addr_list[0] = buf;
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memcpy(h->h_addr_list[0], a, l);
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buf += l;
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h->h_addr_list[1] = 0;
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h->h_aliases[0] = buf;
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h->h_aliases[1] = 0;
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switch (getnameinfo((void *)&sa, sl, buf, buflen, 0, 0, 0)) {
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case EAI_AGAIN:
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*err = TRY_AGAIN;
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return EAGAIN;
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case EAI_OVERFLOW:
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return ERANGE;
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default:
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case EAI_MEMORY:
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case EAI_SYSTEM:
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case EAI_FAIL:
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*err = NO_RECOVERY;
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return errno;
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case 0:
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break;
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}
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h->h_addrtype = af;
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h->h_length = l;
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h->h_name = h->h_aliases[0];
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*res = h;
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return 0;
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}
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