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| 22 | .TH PCAP_FINDALLDEVS 3PCAP "22 August 2010" |
| 23 | .SH NAME |
| 24 | pcap_findalldevs, pcap_freealldevs \- get a list of capture devices, and |
| 25 | free that list |
| 26 | .SH SYNOPSIS |
| 27 | .nf |
| 28 | .ft B |
| 29 | #include <pcap/pcap.h> |
| 30 | .ft |
| 31 | .LP |
| 32 | .nf |
| 33 | .ft B |
| 34 | char errbuf[PCAP_ERRBUF_SIZE]; |
| 35 | .ft |
| 36 | .LP |
| 37 | .ft B |
| 38 | int pcap_findalldevs(pcap_if_t **alldevsp, char *errbuf); |
| 39 | void pcap_freealldevs(pcap_if_t *alldevs); |
| 40 | .ft |
| 41 | .fi |
| 42 | .SH DESCRIPTION |
| 43 | .B pcap_findalldevs() |
| 44 | constructs a list of network devices that can be opened with |
| 45 | .B pcap_create() |
| 46 | and |
| 47 | .B pcap_activate() |
| 48 | or with |
| 49 | .BR pcap_open_live() . |
| 50 | (Note that there may be network devices that cannot be opened by the |
| 51 | process calling |
| 52 | .BR pcap_findalldevs() , |
| 53 | because, for example, that process does not have sufficient privileges |
| 54 | to open them for capturing; if so, those devices will not appear on the |
| 55 | list.) |
| 56 | If |
| 57 | .B pcap_findalldevs() |
| 58 | succeeds, the pointer pointed to by |
| 59 | .I alldevsp |
| 60 | is set to point to the first element of the list, or to |
| 61 | .B NULL |
| 62 | if no devices were found (this is considered success). |
| 63 | Each element of the list is of type |
| 64 | .BR pcap_if_t , |
| 65 | and has the following members: |
| 66 | .RS |
| 67 | .TP |
| 68 | .B next |
| 69 | if not |
| 70 | .BR NULL , |
| 71 | a pointer to the next element in the list; |
| 72 | .B NULL |
| 73 | for the last element of the list |
| 74 | .TP |
| 75 | .B name |
| 76 | a pointer to a string giving a name for the device to pass to |
| 77 | .B pcap_open_live() |
| 78 | .TP |
| 79 | .B description |
| 80 | if not |
| 81 | .BR NULL , |
| 82 | a pointer to a string giving a human-readable description of the device |
| 83 | .TP |
| 84 | .B addresses |
| 85 | a pointer to the first element of a list of network addresses for the |
| 86 | device, |
| 87 | or |
| 88 | .B NULL |
| 89 | if the device has no addresses |
| 90 | .TP |
| 91 | .B flags |
| 92 | device flags: |
| 93 | .RS |
| 94 | .TP |
| 95 | .B PCAP_IF_LOOPBACK |
| 96 | set if the device is a loopback interface |
| 97 | .RE |
| 98 | .RE |
| 99 | .PP |
| 100 | Each element of the list of addresses is of type |
| 101 | .BR pcap_addr_t , |
| 102 | and has the following members: |
| 103 | .RS |
| 104 | .TP |
| 105 | .B next |
| 106 | if not |
| 107 | .BR NULL , |
| 108 | a pointer to the next element in the list; |
| 109 | .B NULL |
| 110 | for the last element of the list |
| 111 | .TP |
| 112 | .B addr |
| 113 | a pointer to a |
| 114 | .B "struct sockaddr" |
| 115 | containing an address |
| 116 | .TP |
| 117 | .B netmask |
| 118 | if not |
| 119 | .BR NULL , |
| 120 | a pointer to a |
| 121 | .B "struct sockaddr" |
| 122 | that contains the netmask corresponding to the address pointed to by |
| 123 | .B addr |
| 124 | .TP |
| 125 | .B broadaddr |
| 126 | if not |
| 127 | .BR NULL , |
| 128 | a pointer to a |
| 129 | .B "struct sockaddr" |
| 130 | that contains the broadcast address corresponding to the address pointed |
| 131 | to by |
| 132 | .BR addr ; |
| 133 | may be null if the device doesn't support broadcasts |
| 134 | .TP |
| 135 | .B dstaddr |
| 136 | if not |
| 137 | .BR NULL , |
| 138 | a pointer to a |
| 139 | .B "struct sockaddr" |
| 140 | that contains the destination address corresponding to the address pointed |
| 141 | to by |
| 142 | .BR addr ; |
| 143 | may be null if the device isn't a point-to-point interface |
| 144 | .RE |
| 145 | .PP |
| 146 | Note that the addresses in the list of addresses might be IPv4 |
| 147 | addresses, IPv6 addresses, or some other type of addresses, so you must |
| 148 | check the |
| 149 | .B sa_family |
| 150 | member of the |
| 151 | .B "struct sockaddr" |
| 152 | before interpreting the contents of the address; do not assume that the |
| 153 | addresses are all IPv4 addresses, or even all IPv4 or IPv6 addresses. |
| 154 | IPv4 addresses have the value |
| 155 | .BR AF_INET , |
| 156 | IPv6 addresses have the value |
| 157 | .B AF_INET6 |
| 158 | (which older operating systems that don't support IPv6 might not |
| 159 | define), and other addresses have other values. Whether other addresses |
| 160 | are returned, and what types they might have is platform-dependent. |
| 161 | For IPv4 addresses, the |
| 162 | .B "struct sockaddr" |
| 163 | pointer can be interpreted as if it pointed to a |
| 164 | .BR "struct sockaddr_in" ; |
| 165 | for IPv6 addresses, it can be interpreted as if it pointed to a |
| 166 | .BR "struct sockaddr_in6". |
| 167 | .PP |
| 168 | The list of devices must be freed with |
| 169 | .BR pcap_freealldevs() , |
| 170 | whch frees the list pointed to by |
| 171 | .IR alldevs . |
| 172 | .SH RETURN VALUE |
| 173 | .B pcap_findalldevs() |
| 174 | returns 0 on success and \-1 on failure; as indicated, finding no |
| 175 | devices is considered success, rather than failure, so 0 will be |
| 176 | returned in that case. |
| 177 | If \-1 is returned, |
| 178 | .I errbuf |
| 179 | is filled in with an appropriate error message. |
| 180 | .I errbuf |
| 181 | is assumed to be able to hold at least |
| 182 | .B PCAP_ERRBUF_SIZE |
| 183 | chars. |
| 184 | .SH SEE ALSO |
| 185 | pcap(3PCAP), pcap_create(3PCAP), pcap_activate(3PCAP), |
| 186 | pcap_open_live(3PCAP) |