pcap.h File Reference

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Unix-compatible Functions

These functions are part of the libpcap library, and therefore work both on Windows and on Linux.
Note:
errbuf in pcap_open_live(), pcap_open_dead(), pcap_open_offline(), pcap_setnonblock(), pcap_getnonblock(), pcap_findalldevs(), pcap_lookupdev(), and pcap_lookupnet() is assumed to be able to hold at least PCAP_ERRBUF_SIZE chars.


typedef void(*) pcap_handler (u_char *user, const struct pcap_pkthdr *pkt_header, const u_char *pkt_data)
 Prototype of the callback function that receives the packets.
pcap_tpcap_open_live (const char *device, int snaplen, int promisc, int to_ms, char *ebuf)
 Open a live capture from the network.
pcap_tpcap_open_dead (int linktype, int snaplen)
 Create a pcap_t structure without starting a capture.
pcap_tpcap_open_offline (const char *fname, char *errbuf)
 Open a savefile in the tcpdump/libpcap format to read packets.
pcap_dumper_tpcap_dump_open (pcap_t *p, const char *fname)
 Open a file to write packets.
int pcap_setnonblock (pcap_t *p, int nonblock, char *errbuf)
 Switch between blocking and nonblocking mode.
int pcap_getnonblock (pcap_t *p, char *errbuf)
 Get the "non-blocking" state of an interface.
int pcap_findalldevs (pcap_if_t **alldevsp, char *errbuf)
 Construct a list of network devices that can be opened with pcap_open_live().
void pcap_freealldevs (pcap_if_t *alldevsp)
 Free an interface list returned by pcap_findalldevs().
char * pcap_lookupdev (char *errbuf)
 Return the first valid device in the system.
int pcap_lookupnet (const char *device, bpf_u_int32 *netp, bpf_u_int32 *maskp, char *errbuf)
 Return the subnet and netmask of an interface.
int pcap_dispatch (pcap_t *p, int cnt, pcap_handler callback, u_char *user)
 Collect a group of packets.
int pcap_loop (pcap_t *p, int cnt, pcap_handler callback, u_char *user)
 Collect a group of packets.
u_char * pcap_next (pcap_t *p, struct pcap_pkthdr *h)
 Return the next available packet.
int pcap_next_ex (pcap_t *p, struct pcap_pkthdr **pkt_header, const u_char **pkt_data)
 Read a packet from an interface or from an offline capture.
void pcap_breakloop (pcap_t *)
 set a flag that will force pcap_dispatch() or pcap_loop() to return rather than looping.
int pcap_sendpacket (pcap_t *p, u_char *buf, int size)
 Send a raw packet.
void pcap_dump (u_char *user, const struct pcap_pkthdr *h, const u_char *sp)
 Save a packet to disk.
long pcap_dump_ftell (pcap_dumper_t *)
 Return the file position for a "savefile".
int pcap_compile (pcap_t *p, struct bpf_program *fp, char *str, int optimize, bpf_u_int32 netmask)
 Compile a packet filter, converting an high level filtering expression (see Filtering expression syntax) in a program that can be interpreted by the kernel-level filtering engine.
int pcap_compile_nopcap (int snaplen_arg, int linktype_arg, struct bpf_program *program, char *buf, int optimize, bpf_u_int32 mask)
 Compile a packet filter without the need of opening an adapter. This function converts an high level filtering expression (see Filtering expression syntax) in a program that can be interpreted by the kernel-level filtering engine.
int pcap_setfilter (pcap_t *p, struct bpf_program *fp)
 Associate a filter to a capture.
void pcap_freecode (struct bpf_program *fp)
 Free a filter.
int pcap_datalink (pcap_t *p)
 Return the link layer of an adapter.
int pcap_list_datalinks (pcap_t *p, int **dlt_buf)
 list datalinks
int pcap_set_datalink (pcap_t *p, int dlt)
 Set the current data link type of the pcap descriptor to the type specified by dlt. -1 is returned on failure.
int pcap_datalink_name_to_val (const char *name)
 Translates a data link type name, which is a DLT_ name with the DLT_ removed, to the corresponding data link type value. The translation is case-insensitive. -1 is returned on failure.
const char * pcap_datalink_val_to_name (int dlt)
 Translates a data link type value to the corresponding data link type name. NULL is returned on failure.
const char * pcap_datalink_val_to_description (int dlt)
 Translates a data link type value to a short description of that data link type. NULL is returned on failure.
int pcap_snapshot (pcap_t *p)
 Return the dimension of the packet portion (in bytes) that is delivered to the application.
int pcap_is_swapped (pcap_t *p)
 returns true if the current savefile uses a different byte order than the current system.
int pcap_major_version (pcap_t *p)
 return the major version number of the pcap library used to write the savefile.
int pcap_minor_version (pcap_t *p)
 return the minor version number of the pcap library used to write the savefile.
FILE * pcap_file (pcap_t *p)
 Return the standard stream of an offline capture.
int pcap_stats (pcap_t *p, struct pcap_stat *ps)
 Return statistics on current capture.
void pcap_perror (pcap_t *p, char *prefix)
 print the text of the last pcap library error on stderr, prefixed by prefix.
char * pcap_geterr (pcap_t *p)
 return the error text pertaining to the last pcap library error.
char * pcap_strerror (int error)
 Provided in case strerror() isn't available.
const char * pcap_lib_version (void)
 Returns a pointer to a string giving information about the version of the libpcap library being used; note that it contains more information than just a version number.
void pcap_close (pcap_t *p)
 close the files associated with p and deallocates resources.
FILE * pcap_dump_file (pcap_dumper_t *p)
 return the standard I/O stream of the 'savefile' opened by pcap_dump_open().
int pcap_dump_flush (pcap_dumper_t *p)
 Flushes the output buffer to the ``savefile,'' so that any packets written with pcap_dump() but not yet written to the ``savefile'' will be written. -1 is returned on error, 0 on success.
void pcap_dump_close (pcap_dumper_t *p)
 Closes a savefile.

Functions

Windows-specific Extensions
The functions in this section extend libpcap to offer advanced functionalities (like remote packet capture, packet buffer size variation or high-precision packet injection). Howerver, at the moment they can be used only in Windows.

PAirpcapHandle pcap_get_airpcap_handle (pcap_t *p)
 Returns the AirPcap handler associated with an adapter. This handler can be used to change the wireless-related settings of the CACE Technologies AirPcap wireless capture adapters.
bool pcap_offline_filter (struct bpf_program *prog, const struct pcap_pkthdr *header, const u_char *pkt_data)
 Returns if a given filter applies to an offline packet.
int pcap_live_dump (pcap_t *p, char *filename, int maxsize, int maxpacks)
 Save a capture to file.
int pcap_live_dump_ended (pcap_t *p, int sync)
 Return the status of the kernel dump process, i.e. tells if one of the limits defined with pcap_live_dump() has been reached.
pcap_statpcap_stats_ex (pcap_t *p, int *pcap_stat_size)
 Return statistics on current capture.
int pcap_setbuff (pcap_t *p, int dim)
 Set the size of the kernel buffer associated with an adapter.
int pcap_setmode (pcap_t *p, int mode)
 Set the working mode of the interface p to mode.
int pcap_setmintocopy (pcap_t *p, int size)
 Set the minumum amount of data received by the kernel in a single call.
HANDLE pcap_getevent (pcap_t *p)
 Return the handle of the event associated with the interface p.
pcap_send_queuepcap_sendqueue_alloc (u_int memsize)
 Allocate a send queue.
void pcap_sendqueue_destroy (pcap_send_queue *queue)
 Destroy a send queue.
int pcap_sendqueue_queue (pcap_send_queue *queue, const struct pcap_pkthdr *pkt_header, const u_char *pkt_data)
 Add a packet to a send queue.
u_int pcap_sendqueue_transmit (pcap_t *p, pcap_send_queue *queue, int sync)
 Send a queue of raw packets to the network.
int pcap_findalldevs_ex (char *source, struct pcap_rmtauth *auth, pcap_if_t **alldevs, char *errbuf)
 Create a list of network devices that can be opened with pcap_open().
int pcap_createsrcstr (char *source, int type, const char *host, const char *port, const char *name, char *errbuf)
 Accept a set of strings (host name, port, ...), and it returns the complete source string according to the new format (e.g. 'rpcap://1.2.3.4/eth0').
int pcap_parsesrcstr (const char *source, int *type, char *host, char *port, char *name, char *errbuf)
 Parse the source string and returns the pieces in which the source can be split.
pcap_tpcap_open (const char *source, int snaplen, int flags, int read_timeout, struct pcap_rmtauth *auth, char *errbuf)
 Open a generic source in order to capture / send (WinPcap only) traffic.
pcap_samppcap_setsampling (pcap_t *p)
 Define a sampling method for packet capture.
SOCKET pcap_remoteact_accept (const char *address, const char *port, const char *hostlist, char *connectinghost, struct pcap_rmtauth *auth, char *errbuf)
 Block until a network connection is accepted (active mode only).
int pcap_remoteact_close (const char *host, char *errbuf)
 Drop an active connection (active mode only).
void pcap_remoteact_cleanup ()
 Clean the socket that is currently used in waiting active connections.
int pcap_remoteact_list (char *hostlist, char sep, int size, char *errbuf)
 Return the hostname of the host that have an active connection with us (active mode only).


documentation. Copyright (c) 2002-2005 Politecnico di Torino. Copyright (c) 2005-2007 CACE Technologies. All rights reserved.