1 | /* Copyright (C) 1999, 2001, 2002 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, write to the Free |
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16 | Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA |
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17 | 02111-1307 USA. */ |
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18 | |
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19 | #include <assert.h> |
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20 | #include <errno.h> |
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21 | #include <stdio.h> |
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22 | #include <string.h> |
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23 | #include <unistd.h> |
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24 | #include <sys/socket.h> |
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25 | #include "libc-symbols.h" |
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26 | |
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27 | /* Return a socket of any type. The socket can be used in subsequent |
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28 | ioctl calls to talk to the kernel. */ |
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29 | int internal_function |
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30 | __opensock (void) |
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31 | { |
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32 | static int last_family; /* Available socket family we will use. */ |
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33 | static int last_type; |
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34 | static const struct |
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35 | { |
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36 | int family; |
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37 | const char procname[15]; |
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38 | } afs[] = |
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39 | { |
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40 | /* The 2.2 kernels cannot handle ioctl(SIOCGIFCONF) on AF_UNIX sockets. |
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41 | Give the kernel a chance to user inet sockets on old kernels. */ |
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42 | #if __LINUX_KERNEL_VERSION < 132096 |
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43 | { AF_INET, "" }, |
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44 | { AF_UNIX, "net/unix" }, |
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45 | #else |
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46 | { AF_UNIX, "net/unix" }, |
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47 | { AF_INET, "" }, |
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48 | #endif |
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49 | { AF_INET6, "net/if_inet6" }, |
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50 | { AF_AX25, "net/ax25" }, |
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51 | { AF_NETROM, "net/nr" }, |
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52 | { AF_ROSE, "net/rose" }, |
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53 | { AF_IPX, "net/ipx" }, |
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54 | { AF_APPLETALK, "net/appletalk" }, |
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55 | { AF_ECONET, "sys/net/econet" }, |
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56 | { AF_ASH, "sys/net/ash" }, |
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57 | { AF_X25, "net/x25" } |
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58 | }; |
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59 | #define nafs (sizeof (afs) / sizeof (afs[0])) |
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60 | char fname[sizeof "/proc/" + 14]; |
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61 | int result; |
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62 | int has_proc; |
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63 | size_t cnt; |
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64 | |
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65 | /* We already know which family to use from the last call. Use it |
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66 | again. */ |
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67 | if (last_family != 0) |
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68 | { |
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69 | assert (last_type != 0); |
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70 | |
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71 | result = socket (last_family, last_type, 0); |
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72 | if (result != -1 || errno != EAFNOSUPPORT) |
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73 | /* Maybe the socket type isn't supported anymore (module is |
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74 | unloaded). In this case again try to find the type. */ |
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75 | return result; |
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76 | |
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77 | /* Reset the values. They seem not valid anymore. */ |
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78 | last_family = 0; |
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79 | last_type = 0; |
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80 | } |
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81 | |
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82 | /* Check whether the /proc filesystem is available. */ |
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83 | has_proc = access ("/proc/net", R_OK) != -1; |
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84 | strcpy (fname, "/proc/"); |
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85 | |
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86 | /* Iterate over the interface families and find one which is |
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87 | available. */ |
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88 | for (cnt = 0; cnt < nafs; ++cnt) |
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89 | { |
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90 | int type = SOCK_DGRAM; |
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91 | |
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92 | if (has_proc && afs[cnt].procname[0] != '\0') |
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93 | { |
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94 | strcpy (fname + 6, afs[cnt].procname); |
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95 | if (access (fname, R_OK) == -1) |
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96 | /* The /proc entry is not available. I.e., we cannot |
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97 | create a socket of this type (without loading the |
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98 | module). Don't look for it since this might trigger |
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99 | loading the module. */ |
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100 | continue; |
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101 | } |
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102 | |
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103 | if (afs[cnt].family == AF_NETROM || afs[cnt].family == AF_X25) |
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104 | type = SOCK_SEQPACKET; |
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105 | |
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106 | result = socket (afs[cnt].family, type, 0); |
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107 | if (result != -1) |
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108 | { |
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109 | /* Found an available family. */ |
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110 | last_type = type; |
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111 | last_family = afs[cnt].family; |
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112 | return result; |
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113 | } |
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114 | } |
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115 | |
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116 | /* None of the protocol families is available. It is unclear what kind |
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117 | of error is returned. ENOENT seems like a reasonable choice. */ |
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118 | __set_errno (ENOENT); |
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119 | return -1; |
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120 | } |
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