| 1 | /* Copyright (C) 1999-2022 Free Software Foundation, Inc. |
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| 2 | This file is part of the GNU C Library. |
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| 3 | |
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| 4 | The GNU C Library is free software; you can redistribute it and/or |
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| 5 | modify it under the terms of the GNU Lesser General Public |
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| 6 | License as published by the Free Software Foundation; either |
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| 7 | version 2.1 of the License, or (at your option) any later version. |
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| 8 | |
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| 9 | The GNU C Library is distributed in the hope that it will be useful, |
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| 10 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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| 12 | Lesser General Public License for more details. |
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| 13 | |
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| 14 | You should have received a copy of the GNU Lesser General Public |
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| 15 | License along with the GNU C Library; if not, see |
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| 16 | <https://www.gnu.org/licenses/>. */ |
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| 17 | |
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| 18 | #include "ifreq.h" |
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| 19 | |
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| 20 | |
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| 21 | void |
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| 22 | __ifreq (struct ifreq **ifreqs, int *num_ifs, int sockfd) |
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| 23 | { |
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| 24 | int fd = sockfd; |
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| 25 | struct ifconf ifc; |
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| 26 | int rq_len; |
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| 27 | int nifs; |
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| 28 | # define RQ_IFS 4 |
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| 29 | |
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| 30 | if (fd < 0) |
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| 31 | fd = __opensock (); |
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| 32 | if (fd < 0) |
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| 33 | { |
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| 34 | *num_ifs = 0; |
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| 35 | *ifreqs = NULL; |
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| 36 | return; |
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| 37 | } |
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| 38 | |
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| 39 | ifc.ifc_buf = NULL; |
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| 40 | |
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| 41 | /* We may be able to get the needed buffer size directly, rather than |
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| 42 | guessing. */ |
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| 43 | ifc.ifc_buf = NULL; |
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| 44 | ifc.ifc_len = 0; |
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| 45 | if (__ioctl (fd, SIOCGIFCONF, &ifc) < 0 || ifc.ifc_len == 0) |
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| 46 | rq_len = RQ_IFS * sizeof (struct ifreq); |
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| 47 | else |
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| 48 | rq_len = ifc.ifc_len; |
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| 49 | |
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| 50 | /* Read all the interfaces out of the kernel. */ |
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| 51 | ifc.ifc_len = rq_len; |
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| 52 | void *newp = realloc (ptr: ifc.ifc_buf, size: ifc.ifc_len); |
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| 53 | if (newp == NULL |
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| 54 | || (ifc.ifc_buf = newp, __ioctl (fd, SIOCGIFCONF, &ifc)) < 0) |
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| 55 | { |
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| 56 | free (ptr: ifc.ifc_buf); |
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| 57 | |
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| 58 | if (fd != sockfd) |
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| 59 | __close (fd); |
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| 60 | |
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| 61 | *num_ifs = 0; |
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| 62 | *ifreqs = NULL; |
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| 63 | return; |
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| 64 | } |
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| 65 | |
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| 66 | nifs = ifc.ifc_len / sizeof (struct ifreq); |
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| 67 | |
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| 68 | if (fd != sockfd) |
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| 69 | __close (fd); |
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| 70 | |
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| 71 | *num_ifs = nifs; |
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| 72 | *ifreqs = realloc (ptr: ifc.ifc_buf, size: nifs * sizeof (struct ifreq)); |
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| 73 | } |
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| 74 | |
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