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115 lines
3.4 KiB
C
115 lines
3.4 KiB
C
/* Copyright (C) 1999-2017 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include <assert.h>
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#include <errno.h>
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#include <stdio.h>
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#include <string.h>
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#include <unistd.h>
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#include <sys/socket.h>
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/* Return a socket of any type. The socket can be used in subsequent
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ioctl calls to talk to the kernel. */
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int
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__opensock (void)
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{
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static int last_family; /* Available socket family we will use. */
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static int last_type;
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static const struct
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{
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int family;
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const char procname[15];
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} afs[] =
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{
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{ AF_UNIX, "net/unix" },
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{ AF_INET, "" },
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{ AF_INET6, "net/if_inet6" },
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{ AF_AX25, "net/ax25" },
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{ AF_NETROM, "net/nr" },
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{ AF_ROSE, "net/rose" },
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{ AF_IPX, "net/ipx" },
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{ AF_APPLETALK, "net/appletalk" },
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{ AF_ECONET, "sys/net/econet" },
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{ AF_ASH, "sys/net/ash" },
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{ AF_X25, "net/x25" },
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#ifdef NEED_AF_IUCV
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{ AF_IUCV, "net/iucv" }
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#endif
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};
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#define nafs (sizeof (afs) / sizeof (afs[0]))
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char fname[sizeof "/proc/" + 14];
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int result;
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int has_proc;
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size_t cnt;
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/* We already know which family to use from the last call. Use it
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again. */
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if (last_family != 0)
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{
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assert (last_type != 0);
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result = __socket (last_family, last_type | SOCK_CLOEXEC, 0);
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if (result != -1 || errno != EAFNOSUPPORT)
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/* Maybe the socket type isn't supported anymore (module is
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unloaded). In this case again try to find the type. */
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return result;
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/* Reset the values. They seem not valid anymore. */
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last_family = 0;
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last_type = 0;
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}
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/* Check whether the /proc filesystem is available. */
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has_proc = __access ("/proc/net", R_OK) != -1;
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strcpy (fname, "/proc/");
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/* Iterate over the interface families and find one which is
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available. */
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for (cnt = 0; cnt < nafs; ++cnt)
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{
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int type = SOCK_DGRAM;
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if (has_proc && afs[cnt].procname[0] != '\0')
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{
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strcpy (fname + 6, afs[cnt].procname);
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if (__access (fname, R_OK) == -1)
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/* The /proc entry is not available. I.e., we cannot
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create a socket of this type (without loading the
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module). Don't look for it since this might trigger
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loading the module. */
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continue;
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}
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if (afs[cnt].family == AF_NETROM || afs[cnt].family == AF_X25)
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type = SOCK_SEQPACKET;
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result = __socket (afs[cnt].family, type | SOCK_CLOEXEC, 0);
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if (result != -1)
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{
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/* Found an available family. */
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last_type = type;
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last_family = afs[cnt].family;
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return result;
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}
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}
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/* None of the protocol families is available. It is unclear what kind
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of error is returned. ENOENT seems like a reasonable choice. */
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__set_errno (ENOENT);
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return -1;
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}
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