?? pcap-linux.c
字號:
#ifndef ARPHRD_FDDI /* From Linux 2.2.13 */
#define ARPHRD_FDDI 774
#endif
case ARPHRD_FDDI:
handle->linktype = DLT_FDDI;
handle->offset = 3;
break;
#ifndef ARPHRD_ATM /* FIXME: How to #include this? */
#define ARPHRD_ATM 19
#endif
case ARPHRD_ATM:
/*
* The Classical IP implementation in ATM for Linux
* supports both what RFC 1483 calls "LLC Encapsulation",
* in which each packet has an LLC header, possibly
* with a SNAP header as well, prepended to it, and
* what RFC 1483 calls "VC Based Multiplexing", in which
* different virtual circuits carry different network
* layer protocols, and no header is prepended to packets.
*
* They both have an ARPHRD_ type of ARPHRD_ATM, so
* you can't use the ARPHRD_ type to find out whether
* captured packets will have an LLC header, and,
* while there's a socket ioctl to *set* the encapsulation
* type, there's no ioctl to *get* the encapsulation type.
*
* This means that
*
* programs that dissect Linux Classical IP frames
* would have to check for an LLC header and,
* depending on whether they see one or not, dissect
* the frame as LLC-encapsulated or as raw IP (I
* don't know whether there's any traffic other than
* IP that would show up on the socket, or whether
* there's any support for IPv6 in the Linux
* Classical IP code);
*
* filter expressions would have to compile into
* code that checks for an LLC header and does
* the right thing.
*
* Both of those are a nuisance - and, at least on systems
* that support PF_PACKET sockets, we don't have to put
* up with those nuisances; instead, we can just capture
* in cooked mode. That's what we'll do, if we can.
* Otherwise, we'll just fail.
*/
if (cooked_ok)
handle->linktype = DLT_LINUX_SLL;
else
handle->linktype = -1;
break;
#ifndef ARPHRD_IEEE80211 /* From Linux 2.4.6 */
#define ARPHRD_IEEE80211 801
#endif
case ARPHRD_IEEE80211:
handle->linktype = DLT_IEEE802_11;
break;
#ifndef ARPHRD_IEEE80211_PRISM /* From Linux 2.4.18 */
#define ARPHRD_IEEE80211_PRISM 802
#endif
case ARPHRD_IEEE80211_PRISM:
handle->linktype = DLT_PRISM_HEADER;
break;
case ARPHRD_PPP:
/*
* Some PPP code in the kernel supplies no link-layer
* header whatsoever to PF_PACKET sockets; other PPP
* code supplies PPP link-layer headers ("syncppp.c");
* some PPP code might supply random link-layer
* headers (PPP over ISDN - there's code in Ethereal,
* for example, to cope with PPP-over-ISDN captures
* with which the Ethereal developers have had to cope,
* heuristically trying to determine which of the
* oddball link-layer headers particular packets have).
*
* As such, we just punt, and run all PPP interfaces
* in cooked mode, if we can; otherwise, we just treat
* it as DLT_RAW, for now - if somebody needs to capture,
* on a 2.0[.x] kernel, on PPP devices that supply a
* link-layer header, they'll have to add code here to
* map to the appropriate DLT_ type (possibly adding a
* new DLT_ type, if necessary).
*/
if (cooked_ok)
handle->linktype = DLT_LINUX_SLL;
else {
/*
* XXX - handle ISDN types here? We can't fall
* back on cooked sockets, so we'd have to
* figure out from the device name what type of
* link-layer encapsulation it's using, and map
* that to an appropriate DLT_ value, meaning
* we'd map "isdnN" devices to DLT_RAW (they
* supply raw IP packets with no link-layer
* header) and "isdY" devices to a new DLT_I4L_IP
* type that has only an Ethernet packet type as
* a link-layer header.
*
* But sometimes we seem to get random crap
* in the link-layer header when capturing on
* ISDN devices....
*/
handle->linktype = DLT_RAW;
}
break;
#ifndef ARPHRD_CISCO
#define ARPHRD_CISCO 513 /* previously ARPHRD_HDLC */
#endif
case ARPHRD_CISCO:
handle->linktype = DLT_C_HDLC;
break;
/* Not sure if this is correct for all tunnels, but it
* works for CIPE */
case ARPHRD_TUNNEL:
#ifndef ARPHRD_SIT
#define ARPHRD_SIT 776 /* From Linux 2.2.13 */
#endif
case ARPHRD_SIT:
case ARPHRD_CSLIP:
case ARPHRD_SLIP6:
case ARPHRD_CSLIP6:
case ARPHRD_ADAPT:
case ARPHRD_SLIP:
#ifndef ARPHRD_RAWHDLC
#define ARPHRD_RAWHDLC 518
#endif
case ARPHRD_RAWHDLC:
#ifndef ARPHRD_DLCI
#define ARPHRD_DLCI 15
#endif
case ARPHRD_DLCI:
/*
* XXX - should some of those be mapped to DLT_LINUX_SLL
* instead? Should we just map all of them to DLT_LINUX_SLL?
*/
handle->linktype = DLT_RAW;
break;
#ifndef ARPHRD_FRAD
#define ARPHRD_FRAD 770
#endif
case ARPHRD_FRAD:
handle->linktype = DLT_FRELAY;
break;
case ARPHRD_LOCALTLK:
handle->linktype = DLT_LTALK;
break;
#ifndef ARPHRD_FCPP
#define ARPHRD_FCPP 784
#endif
case ARPHRD_FCPP:
#ifndef ARPHRD_FCAL
#define ARPHRD_FCAL 785
#endif
case ARPHRD_FCAL:
#ifndef ARPHRD_FCPL
#define ARPHRD_FCPL 786
#endif
case ARPHRD_FCPL:
#ifndef ARPHRD_FCFABRIC
#define ARPHRD_FCFABRIC 787
#endif
case ARPHRD_FCFABRIC:
/*
* We assume that those all mean RFC 2625 IP-over-
* Fibre Channel, with the RFC 2625 header at
* the beginning of the packet.
*/
handle->linktype = DLT_IP_OVER_FC;
break;
#ifndef ARPHRD_IRDA
#define ARPHRD_IRDA 783
#endif
case ARPHRD_IRDA:
/* Don't expect IP packet out of this interfaces... */
handle->linktype = DLT_LINUX_IRDA;
/* We need to save packet direction for IrDA decoding,
* so let's use "Linux-cooked" mode. Jean II */
//handle->md.cooked = 1;
break;
default:
handle->linktype = -1;
break;
}
}
/* ===== Functions to interface to the newer kernels ================== */
/*
* Try to open a packet socket using the new kernel interface.
* Returns 0 on failure.
* FIXME: 0 uses to mean success (Sebastian)
*/
static int
live_open_new(pcap_t *handle, const char *device, int promisc,
int to_ms, char *ebuf)
{
#ifdef HAVE_PF_PACKET_SOCKETS
int sock_fd = -1, device_id, arptype;
int err;
int fatal_err = 0;
struct packet_mreq mr;
/* One shot loop used for error handling - bail out with break */
do {
/*
* Open a socket with protocol family packet. If a device is
* given we try to open it in raw mode otherwise we use
* the cooked interface.
*/
sock_fd = device ?
socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL))
: socket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_ALL));
if (sock_fd == -1) {
snprintf(ebuf, PCAP_ERRBUF_SIZE, "socket: %s",
pcap_strerror(errno) );
break;
}
/* It seems the kernel supports the new interface. */
handle->md.sock_packet = 0;
/*
* Get the interface index of the loopback device.
* If the attempt fails, don't fail, just set the
* "md.lo_ifindex" to -1.
*
* XXX - can there be more than one device that loops
* packets back, i.e. devices other than "lo"? If so,
* we'd need to find them all, and have an array of
* indices for them, and check all of them in
* "pcap_read_packet()".
*/
handle->md.lo_ifindex = iface_get_id(sock_fd, "lo", ebuf);
/*
* Default value for offset to align link-layer payload
* on a 4-byte boundary.
*/
handle->offset = 0;
/*
* What kind of frames do we have to deal with? Fall back
* to cooked mode if we have an unknown interface type.
*/
if (device) {
/* Assume for now we don't need cooked mode. */
handle->md.cooked = 0;
arptype = iface_get_arptype(sock_fd, device, ebuf);
if (arptype == -1) {
fatal_err = 1;
break;
}
map_arphrd_to_dlt(handle, arptype, 1);
if (handle->linktype == -1 ||
handle->linktype == DLT_LINUX_SLL ||
handle->linktype == DLT_LINUX_IRDA ||
(handle->linktype == DLT_EN10MB &&
(strncmp("isdn", device, 4) == 0 ||
strncmp("isdY", device, 4) == 0))) {
/*
* Unknown interface type (-1), or a
* device we explicitly chose to run
* in cooked mode (e.g., PPP devices),
* or an ISDN device (whose link-layer
* type we can only determine by using
* APIs that may be different on different
* kernels) - reopen in cooked mode.
*/
if (close(sock_fd) == -1) {
snprintf(ebuf, PCAP_ERRBUF_SIZE,
"close: %s", pcap_strerror(errno));
break;
}
sock_fd = socket(PF_PACKET, SOCK_DGRAM,
htons(ETH_P_ALL));
if (sock_fd == -1) {
snprintf(ebuf, PCAP_ERRBUF_SIZE,
"socket: %s", pcap_strerror(errno));
break;
}
handle->md.cooked = 1;
if (handle->linktype == -1) {
/*
* Warn that we're falling back on
* cooked mode; we may want to
* update "map_arphrd_to_dlt()"
* to handle the new type.
*/
snprintf(ebuf, PCAP_ERRBUF_SIZE,
"arptype %d not "
"supported by libpcap - "
"falling back to cooked "
"socket",
arptype);
}
/* IrDA capture is not a real "cooked" capture,
* it's IrLAP frames, not IP packets. */
if(handle->linktype != DLT_LINUX_IRDA)
handle->linktype = DLT_LINUX_SLL;
}
device_id = iface_get_id(sock_fd, device, ebuf);
if (device_id == -1)
break;
if ((err = iface_bind(sock_fd, device_id, ebuf)) < 0) {
if (err == -2)
fatal_err = 1;
break;
}
} else {
/*
* This is cooked mode.
*/
handle->md.cooked = 1;
handle->linktype = DLT_LINUX_SLL;
/*
* XXX - squelch GCC complaints about
* uninitialized variables; if we can't
* select promiscuous mode on all interfaces,
* we should move the code below into the
* "if (device)" branch of the "if" and
* get rid of the next statement.
*/
device_id = -1;
}
/*
* Select promiscuous mode on if "promisc" is set.
*
* Do not turn allmulti mode on if we don't select
* promiscuous mode - on some devices (e.g., Orinoco
* wireless interfaces), allmulti mode isn't supported
* and the driver implements it by turning promiscuous
* mode on, and that screws up the operation of the
* card as a normal networking interface, and on no
* other platform I know of does starting a non-
* promiscuous capture affect which multicast packets
* are received by the interface.
*/
/*
* Hmm, how can we set promiscuous mode on all interfaces?
* I am not sure if that is possible at all.
*/
if (device && promisc) {
memset(&mr, 0, sizeof(mr));
mr.mr_ifindex = device_id;
mr.mr_type = PACKET_MR_PROMISC;
if (setsockopt(sock_fd, SOL_PACKET,
PACKET_ADD_MEMBERSHIP, &mr, sizeof(mr)) == -1)
{
snprintf(ebuf, PCAP_ERRBUF_SIZE,
"setsockopt: %s", pcap_strerror(errno));
break;
}
}
/* Save the socket FD in the pcap structure */
handle->fd = sock_fd;
return 1;
} while(0);
if (sock_fd != -1)
close(sock_fd);
if (fatal_err)
return -2;
else
return 0;
#else
strncpy(ebuf,
"New packet capturing interface not supported by build "
"environment", PCAP_ERRBUF_SIZE);
return 0;
#endif
}
#ifdef HAVE_PF_PACKET_SOCKETS
/*
* Return the index of the given device name. Fill ebuf and return
* -1 on failure.
*/
static int
iface_get_id(int fd, const char *device, char *ebuf)
{
struct ifreq ifr;
memset(&ifr, 0, sizeof(ifr));
strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
if (ioctl(fd, SIOCGIFINDEX, &ifr) == -1) {
snprintf(ebuf, PCAP_ERRBUF_SIZE,
"ioctl: %s", pcap_strerror(errno));
return -1;
}
return ifr.ifr_ifindex;
}
/*
* Bind the socket associated with FD to the given device.
*/
static int
iface_bind(int fd, int ifindex, char *ebuf)
{
struct sockaddr_ll sll;
int err;
socklen_t errlen = sizeof(err);
memset(&sll, 0, sizeof(sll));
sll.sll_family = AF_PACKET;
sll.sll_ifindex = ifindex;
sll.sll_protocol = htons(ETH_P_ALL);
if (bind(fd, (struct sockaddr *) &sll, sizeof(sll)) == -1) {
snprintf(ebuf, PCAP_ERRBUF_SIZE,
"bind: %s", pcap_strerror(errno));
return -1;
}
/* Any pending errors, e.g., network is down? */
if (getsockopt(fd, SOL_SOCKET, SO_ERROR, &err, &errlen) == -1) {
snprintf(ebuf, PCAP_ERRBUF_SIZE,
"getsockopt: %s", pcap_strerror(errno));
return -2;
}
if (err > 0) {
snprintf(ebuf, PCAP_ERRBUF_SIZE,
"bind: %s", pcap_strerror(err));
return -2;
}
return 0;
}
#endif
/* ===== Functions to interface to the older kernels ================== */
/*
* With older kernels promiscuous mode is kind of interesting because we
* have to reset the interface before exiting. The problem can't really
* be solved without some daemon taking care of managing usage counts.
* If we put the interface into promiscuous mode, we set a flag indicating
* that we must take it out of that mode when the interface is closed,
* and, when closing the interface, if that flag is set we take it out
* of promiscuous mode.
*/
/*
* List of pcaps for which we turned promiscuous mode on by hand.
* If there are any such pcaps, we arrange to call "pcap_close_all()"
* when we exit, and have it close all of them to turn promiscuous mode
* off.
*/
static struct pcap *pcaps_to_close;
/*
* TRUE if we've already called "atexit()" to cause "pcap_close_all()" to
* be called on exit.
*/
static int did_atexit;
static void pcap_close_all(void)
{
struct pcap *handle;
while ((handle = pcaps_to_close) != NULL)
pcap_close(handle);
}
static void pcap_close_linux( pcap_t *handle )
{
struct pcap *p, *prevp;
struct ifreq ifr;
if (handle->md.clear_promisc) {
/*
* We put the interface into promiscuous mode; take
* it out of promiscuous mode.
*
* XXX - if somebody else wants it in promiscuous mode,
* this code cannot know that, so it'll take it out
* of promiscuous mode. That's not fixable in 2.0[.x]
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