| JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 1 | .\" @(#) $Header: /tcpdump/master/libpcap/pcap_datalink.3pcap.in,v 1.1 2008-10-21 07:33:02 guy Exp $ |
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| 22 | .TH PCAP_DATALINK 3PCAP "22 August 2010" |
| 23 | .SH NAME |
| 24 | pcap_datalink \- get the link-layer header type |
| 25 | .SH SYNOPSIS |
| 26 | .nf |
| 27 | .ft B |
| 28 | #include <pcap/pcap.h> |
| 29 | .ft |
| 30 | .LP |
| 31 | .ft B |
| 32 | int pcap_datalink(pcap_t *p); |
| 33 | .ft |
| 34 | .fi |
| 35 | .SH DESCRIPTION |
| 36 | .B pcap_datalink() |
| 37 | returns the link-layer header type for the live capture or ``savefile'' |
| 38 | specified by |
| 39 | .IR p . |
| 40 | .PP |
| 41 | It must not be called on a pcap descriptor created by |
| 42 | .B pcap_create() |
| 43 | that has not yet been activated by |
| 44 | .BR pcap_activate() . |
| 45 | .PP |
| 46 | .I http://www.tcpdump.org/linktypes.html |
| 47 | lists the values |
| 48 | .B pcap_datalink() |
| 49 | can return and describes the packet formats that |
| 50 | correspond to those values. |
| 51 | .PP |
| 52 | Do |
| 53 | .B NOT |
| 54 | assume that the packets for a given capture or ``savefile`` will have |
| 55 | any given link-layer header type, such as |
| 56 | .B DLT_EN10MB |
| 57 | for Ethernet. For example, the "any" device on Linux will have a |
| 58 | link-layer header type of |
| 59 | .B DLT_LINUX_SLL |
| 60 | even if all devices on the system at the time the "any" device is opened |
| 61 | have some other data link type, such as |
| 62 | .B DLT_EN10MB |
| 63 | for Ethernet. |
| 64 | .SH RETURN VALUE |
| 65 | .B pcap_datalink() |
| 66 | returns the link-layer header type on success and |
| 67 | .B PCAP_ERROR_NOT_ACTIVATED |
| 68 | if called on a capture handle that has been created but not activated. |
| 69 | .SH SEE ALSO |
| 70 | pcap(3PCAP), pcap-linktype(@MAN_MISC_INFO@) |