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Elliott Hughes | 965a4b5 | 2017-05-15 10:37:39 -0700 | [diff] [blame] | 20 | .TH PCAP_DATALINK 3PCAP "7 April 2014" |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 21 | .SH NAME |
| 22 | pcap_datalink \- get the link-layer header type |
| 23 | .SH SYNOPSIS |
| 24 | .nf |
| 25 | .ft B |
| 26 | #include <pcap/pcap.h> |
| 27 | .ft |
| 28 | .LP |
| 29 | .ft B |
| 30 | int pcap_datalink(pcap_t *p); |
| 31 | .ft |
| 32 | .fi |
| 33 | .SH DESCRIPTION |
Haibo Huang | ee759ce | 2021-01-05 21:34:29 -0800 | [diff] [blame^] | 34 | .BR pcap_datalink () |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 35 | returns the link-layer header type for the live capture or ``savefile'' |
| 36 | specified by |
| 37 | .IR p . |
| 38 | .PP |
| 39 | It must not be called on a pcap descriptor created by |
Haibo Huang | ee759ce | 2021-01-05 21:34:29 -0800 | [diff] [blame^] | 40 | .BR \%pcap_create (3PCAP) |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 41 | that has not yet been activated by |
Haibo Huang | ee759ce | 2021-01-05 21:34:29 -0800 | [diff] [blame^] | 42 | .BR \%pcap_activate (3PCAP). |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 43 | .PP |
Haibo Huang | 165065a | 2018-07-23 17:26:52 -0700 | [diff] [blame] | 44 | .I https://www.tcpdump.org/linktypes.html |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 45 | lists the values |
Haibo Huang | ee759ce | 2021-01-05 21:34:29 -0800 | [diff] [blame^] | 46 | .BR pcap_datalink () |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 47 | can return and describes the packet formats that |
| 48 | correspond to those values. |
| 49 | .PP |
| 50 | Do |
| 51 | .B NOT |
| 52 | assume that the packets for a given capture or ``savefile`` will have |
| 53 | any given link-layer header type, such as |
| 54 | .B DLT_EN10MB |
| 55 | for Ethernet. For example, the "any" device on Linux will have a |
| 56 | link-layer header type of |
| 57 | .B DLT_LINUX_SLL |
Haibo Huang | ee759ce | 2021-01-05 21:34:29 -0800 | [diff] [blame^] | 58 | or |
| 59 | .B DLT_LINUX_SLL2 |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 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 |
Haibo Huang | ee759ce | 2021-01-05 21:34:29 -0800 | [diff] [blame^] | 65 | .BR pcap_datalink () |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 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 |
Haibo Huang | ee759ce | 2021-01-05 21:34:29 -0800 | [diff] [blame^] | 70 | .BR pcap (3PCAP), |
| 71 | .BR pcap-linktype (@MAN_MISC_INFO@) |