1 | #define _GNU_SOURCE
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2 |
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3 | #include <sys/socket.h>
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4 | #include <netdb.h>
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5 | #include <string.h>
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6 | #include <netinet/in.h>
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7 | #include <errno.h>
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8 | #include <inttypes.h>
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9 |
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10 | int gethostbyaddr_r(const void *a, socklen_t l, int af,
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11 | struct hostent *h, char *buf, size_t buflen,
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12 | struct hostent **res, int *err)
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13 | {
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14 | union {
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15 | struct sockaddr_in sin;
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16 | struct sockaddr_in6 sin6;
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17 | } sa = { .sin.sin_family = af };
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18 | socklen_t sl = af==AF_INET6 ? sizeof sa.sin6 : sizeof sa.sin;
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19 | int i;
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20 |
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21 | *res = 0;
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22 |
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23 | /* Load address argument into sockaddr structure */
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24 | if (af==AF_INET6 && l==16) memcpy(&sa.sin6.sin6_addr, a, 16);
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25 | else if (af==AF_INET && l==4) memcpy(&sa.sin.sin_addr, a, 4);
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26 | else {
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27 | *err = NO_RECOVERY;
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28 | return EINVAL;
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29 | }
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30 |
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31 | /* Align buffer and check for space for pointers and ip address */
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32 | i = (uintptr_t)buf & sizeof(char *)-1;
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33 | if (!i) i = sizeof(char *);
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34 | if (buflen <= 5*sizeof(char *)-i + l) return ERANGE;
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35 | buf += sizeof(char *)-i;
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36 | buflen -= 5*sizeof(char *)-i + l;
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37 |
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38 | h->h_addr_list = (void *)buf;
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39 | buf += 2*sizeof(char *);
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40 | h->h_aliases = (void *)buf;
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41 | buf += 2*sizeof(char *);
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42 |
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43 | h->h_addr_list[0] = buf;
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44 | memcpy(h->h_addr_list[0], a, l);
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45 | buf += l;
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46 | h->h_addr_list[1] = 0;
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47 | h->h_aliases[0] = buf;
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48 | h->h_aliases[1] = 0;
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49 |
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50 | switch (getnameinfo((void *)&sa, sl, buf, buflen, 0, 0, 0)) {
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51 | case EAI_AGAIN:
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52 | *err = TRY_AGAIN;
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53 | return EAGAIN;
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54 | case EAI_OVERFLOW:
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55 | return ERANGE;
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56 | default:
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57 | case EAI_MEMORY:
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58 | case EAI_SYSTEM:
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59 | case EAI_FAIL:
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60 | *err = NO_RECOVERY;
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61 | return errno;
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62 | case 0:
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63 | break;
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64 | }
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65 |
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66 | h->h_addrtype = af;
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67 | h->h_length = l;
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68 | h->h_name = h->h_aliases[0];
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69 | *res = h;
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70 | return 0;
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71 | }
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