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Diffstat (limited to 'pcap-bpf.c')
| -rw-r--r-- | pcap-bpf.c | 1158 |
1 files changed, 1158 insertions, 0 deletions
diff --git a/pcap-bpf.c b/pcap-bpf.c new file mode 100644 index 0000000..027913e --- /dev/null +++ b/pcap-bpf.c @@ -0,0 +1,1158 @@ +/* + * Copyright (c) 1993, 1994, 1995, 1996, 1998 + * The Regents of the University of California. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that: (1) source code distributions + * retain the above copyright notice and this paragraph in its entirety, (2) + * distributions including binary code include the above copyright notice and + * this paragraph in its entirety in the documentation or other materials + * provided with the distribution, and (3) all advertising materials mentioning + * features or use of this software display the following acknowledgement: + * ``This product includes software developed by the University of California, + * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of + * the University nor the names of its contributors may be used to endorse + * or promote products derived from this software without specific prior + * written permission. + * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED + * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF + * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. + */ +#ifndef lint +static const char rcsid[] _U_ = + "@(#) $Header: /tcpdump/master/libpcap/pcap-bpf.c,v 1.86.2.12 2007/06/15 17:57:27 guy Exp $ (LBL)"; +#endif + +#ifdef HAVE_CONFIG_H +#include "config.h" +#endif + +#include <sys/param.h> /* optionally get BSD define */ +#include <sys/time.h> +#include <sys/timeb.h> +#include <sys/socket.h> +#include <sys/file.h> +#include <sys/ioctl.h> +#include <sys/utsname.h> + +#include <net/if.h> + +#ifdef _AIX + +/* + * Make "pcap.h" not include "pcap-bpf.h"; we are going to include the + * native OS version, as we need "struct bpf_config" from it. + */ +#define PCAP_DONT_INCLUDE_PCAP_BPF_H + +#include <sys/types.h> + +/* + * Prevent bpf.h from redefining the DLT_ values to their + * IFT_ values, as we're going to return the standard libpcap + * values, not IBM's non-standard IFT_ values. + */ +#undef _AIX +#include <net/bpf.h> +#define _AIX + +#include <net/if_types.h> /* for IFT_ values */ +#include <sys/sysconfig.h> +#include <sys/device.h> +#include <sys/cfgodm.h> +#include <cf.h> + +#ifdef __64BIT__ +#define domakedev makedev64 +#define getmajor major64 +#define bpf_hdr bpf_hdr32 +#else /* __64BIT__ */ +#define domakedev makedev +#define getmajor major +#endif /* __64BIT__ */ + +#define BPF_NAME "bpf" +#define BPF_MINORS 4 +#define DRIVER_PATH "/usr/lib/drivers" +#define BPF_NODE "/dev/bpf" +static int bpfloadedflag = 0; +static int odmlockid = 0; + +#else /* _AIX */ + +#include <net/bpf.h> + +#endif /* _AIX */ + +#include <ctype.h> +#include <errno.h> +#include <netdb.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <unistd.h> + +#include "pcap-int.h" + +#ifdef HAVE_DAG_API +#include "pcap-dag.h" +#endif /* HAVE_DAG_API */ + +#ifdef HAVE_OS_PROTO_H +#include "os-proto.h" +#endif + +#include "gencode.h" /* for "no_optimize" */ + +static int pcap_setfilter_bpf(pcap_t *p, struct bpf_program *fp); +static int pcap_setdirection_bpf(pcap_t *, pcap_direction_t); +static int pcap_set_datalink_bpf(pcap_t *p, int dlt); + +static int +pcap_stats_bpf(pcap_t *p, struct pcap_stat *ps) +{ + struct bpf_stat s; + + /* + * "ps_recv" counts packets handed to the filter, not packets + * that passed the filter. This includes packets later dropped + * because we ran out of buffer space. + * + * "ps_drop" counts packets dropped inside the BPF device + * because we ran out of buffer space. It doesn't count + * packets dropped by the interface driver. It counts + * only packets that passed the filter. + * + * Both statistics include packets not yet read from the kernel + * by libpcap, and thus not yet seen by the application. + */ + if (ioctl(p->fd, BIOCGSTATS, (caddr_t)&s) < 0) { + snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "BIOCGSTATS: %s", + pcap_strerror(errno)); + return (-1); + } + + ps->ps_recv = s.bs_recv; + ps->ps_drop = s.bs_drop; + return (0); +} + +static int +pcap_read_bpf(pcap_t *p, int cnt, pcap_handler callback, u_char *user) +{ + int cc; + int n = 0; + register u_char *bp, *ep; + u_char *datap; + struct bpf_insn *fcode; +#ifdef PCAP_FDDIPAD + register int pad; +#endif + + fcode = p->md.use_bpf ? NULL : p->fcode.bf_insns; + again: + /* + * Has "pcap_breakloop()" been called? + */ + if (p->break_loop) { + /* + * Yes - clear the flag that indicates that it + * has, and return -2 to indicate that we were + * told to break out of the loop. + */ + p->break_loop = 0; + return (-2); + } + cc = p->cc; + if (p->cc == 0) { + cc = read(p->fd, (char *)p->buffer, p->bufsize); + if (cc < 0) { + /* Don't choke when we get ptraced */ + switch (errno) { + + case EINTR: + goto again; + +#ifdef _AIX + case EFAULT: + /* + * Sigh. More AIX wonderfulness. + * + * For some unknown reason the uiomove() + * operation in the bpf kernel extension + * used to copy the buffer into user + * space sometimes returns EFAULT. I have + * no idea why this is the case given that + * a kernel debugger shows the user buffer + * is correct. This problem appears to + * be mostly mitigated by the memset of + * the buffer before it is first used. + * Very strange.... Shaun Clowes + * + * In any case this means that we shouldn't + * treat EFAULT as a fatal error; as we + * don't have an API for returning + * a "some packets were dropped since + * the last packet you saw" indication, + * we just ignore EFAULT and keep reading. + */ + goto again; +#endif + + case EWOULDBLOCK: + return (0); +#if defined(sun) && !defined(BSD) + /* + * Due to a SunOS bug, after 2^31 bytes, the kernel + * file offset overflows and read fails with EINVAL. + * The lseek() to 0 will fix things. + */ + case EINVAL: + if (lseek(p->fd, 0L, SEEK_CUR) + + p->bufsize < 0) { + (void)lseek(p->fd, 0L, SEEK_SET); + goto again; + } + /* fall through */ +#endif + } + snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "read: %s", + pcap_strerror(errno)); + return (-1); + } + bp = p->buffer; + } else + bp = p->bp; + + /* + * Loop through each packet. + */ +#define bhp ((struct bpf_hdr *)bp) + ep = bp + cc; +#ifdef PCAP_FDDIPAD + pad = p->fddipad; +#endif + while (bp < ep) { + register int caplen, hdrlen; + + /* + * Has "pcap_breakloop()" been called? + * If so, return immediately - if we haven't read any + * packets, clear the flag and return -2 to indicate + * that we were told to break out of the loop, otherwise + * leave the flag set, so that the *next* call will break + * out of the loop without having read any packets, and + * return the number of packets we've processed so far. + */ + if (p->break_loop) { + if (n == 0) { + p->break_loop = 0; + return (-2); + } else { + p->bp = bp; + p->cc = ep - bp; + return (n); + } + } + + caplen = bhp->bh_caplen; + hdrlen = bhp->bh_hdrlen; + datap = bp + hdrlen; + /* + * Short-circuit evaluation: if using BPF filter + * in kernel, no need to do it now. + * +#ifdef PCAP_FDDIPAD + * Note: the filter code was generated assuming + * that p->fddipad was the amount of padding + * before the header, as that's what's required + * in the kernel, so we run the filter before + * skipping that padding. +#endif + */ + if (fcode == NULL || + bpf_filter(fcode, datap, bhp->bh_datalen, caplen)) { + struct pcap_pkthdr pkthdr; + + pkthdr.ts.tv_sec = bhp->bh_tstamp.tv_sec; +#ifdef _AIX + /* + * AIX's BPF returns seconds/nanoseconds time + * stamps, not seconds/microseconds time stamps. + */ + pkthdr.ts.tv_usec = bhp->bh_tstamp.tv_usec/1000; +#else + pkthdr.ts.tv_usec = bhp->bh_tstamp.tv_usec; +#endif +#ifdef PCAP_FDDIPAD + if (caplen > pad) + pkthdr.caplen = caplen - pad; + else + pkthdr.caplen = 0; + if (bhp->bh_datalen > pad) + pkthdr.len = bhp->bh_datalen - pad; + else + pkthdr.len = 0; + datap += pad; +#else + pkthdr.caplen = caplen; + pkthdr.len = bhp->bh_datalen; +#endif + (*callback)(user, &pkthdr, datap); + bp += BPF_WORDALIGN(caplen + hdrlen); + if (++n >= cnt && cnt > 0) { + p->bp = bp; + p->cc = ep - bp; + return (n); + } + } else { + /* + * Skip this packet. + */ + bp += BPF_WORDALIGN(caplen + hdrlen); + } + } +#undef bhp + p->cc = 0; + return (n); +} + +static int +pcap_inject_bpf(pcap_t *p, const void *buf, size_t size) +{ + int ret; + + ret = write(p->fd, buf, size); +#ifdef __APPLE__ + if (ret == -1 && errno == EAFNOSUPPORT) { + /* + * In Mac OS X, there's a bug wherein setting the + * BIOCSHDRCMPLT flag causes writes to fail; see, + * for example: + * + * http://cerberus.sourcefire.com/~jeff/archives/patches/macosx/BIOCSHDRCMPLT-10.3.3.patch + * + * So, if, on OS X, we get EAFNOSUPPORT from the write, we + * assume it's due to that bug, and turn off that flag + * and try again. If we succeed, it either means that + * somebody applied the fix from that URL, or other patches + * for that bug from + * + * http://cerberus.sourcefire.com/~jeff/archives/patches/macosx/ + * + * and are running a Darwin kernel with those fixes, or + * that Apple fixed the problem in some OS X release. + */ + u_int spoof_eth_src = 0; + + if (ioctl(p->fd, BIOCSHDRCMPLT, &spoof_eth_src) == -1) { + (void)snprintf(p->errbuf, PCAP_ERRBUF_SIZE, + "send: can't turn off BIOCSHDRCMPLT: %s", + pcap_strerror(errno)); + return (-1); + } + + /* + * Now try the write again. + */ + ret = write(p->fd, buf, size); + } +#endif /* __APPLE__ */ + if (ret == -1) { + snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "send: %s", + pcap_strerror(errno)); + return (-1); + } + return (ret); +} + +#ifdef _AIX +static int +bpf_odminit(char *errbuf) +{ + char *errstr; + + if (odm_initialize() == -1) { + if (odm_err_msg(odmerrno, &errstr) == -1) + errstr = "Unknown error"; + snprintf(errbuf, PCAP_ERRBUF_SIZE, + "bpf_load: odm_initialize failed: %s", + errstr); + return (-1); + } + + if ((odmlockid = odm_lock("/etc/objrepos/config_lock", ODM_WAIT)) == -1) { + if (odm_err_msg(odmerrno, &errstr) == -1) + errstr = "Unknown error"; + snprintf(errbuf, PCAP_ERRBUF_SIZE, + "bpf_load: odm_lock of /etc/objrepos/config_lock failed: %s", + errstr); + return (-1); + } + + return (0); +} + +static int +bpf_odmcleanup(char *errbuf) +{ + char *errstr; + + if (odm_unlock(odmlockid) == -1) { + if (odm_err_msg(odmerrno, &errstr) == -1) + errstr = "Unknown error"; + snprintf(errbuf, PCAP_ERRBUF_SIZE, + "bpf_load: odm_unlock failed: %s", + errstr); + return (-1); + } + + if (odm_terminate() == -1) { + if (odm_err_msg(odmerrno, &errstr) == -1) + errstr = "Unknown error"; + snprintf(errbuf, PCAP_ERRBUF_SIZE, + "bpf_load: odm_terminate failed: %s", + errstr); + return (-1); + } + + return (0); +} + +static int +bpf_load(char *errbuf) +{ + long major; + int *minors; + int numminors, i, rc; + char buf[1024]; + struct stat sbuf; + struct bpf_config cfg_bpf; + struct cfg_load cfg_ld; + struct cfg_kmod cfg_km; + + /* + * This is very very close to what happens in the real implementation + * but I've fixed some (unlikely) bug situations. + */ + if (bpfloadedflag) + return (0); + + if (bpf_odminit(errbuf) != 0) + return (-1); + + major = genmajor(BPF_NAME); + if (major == -1) { + snprintf(errbuf, PCAP_ERRBUF_SIZE, + "bpf_load: genmajor failed: %s", pcap_strerror(errno)); + return (-1); + } + + minors = getminor(major, &numminors, BPF_NAME); + if (!minors) { + minors = genminor("bpf", major, 0, BPF_MINORS, 1, 1); + if (!minors) { + snprintf(errbuf, PCAP_ERRBUF_SIZE, + "bpf_load: genminor failed: %s", + pcap_strerror(errno)); + return (-1); + } + } + + if (bpf_odmcleanup(errbuf)) + return (-1); + + rc = stat(BPF_NODE "0", &sbuf); + if (rc == -1 && errno != ENOENT) { + snprintf(errbuf, PCAP_ERRBUF_SIZE, + "bpf_load: can't stat %s: %s", + BPF_NODE "0", pcap_strerror(errno)); + return (-1); + } + + if (rc == -1 || getmajor(sbuf.st_rdev) != major) { + for (i = 0; i < BPF_MINORS; i++) { + sprintf(buf, "%s%d", BPF_NODE, i); + unlink(buf); + if (mknod(buf, S_IRUSR | S_IFCHR, domakedev(major, i)) == -1) { + snprintf(errbuf, PCAP_ERRBUF_SIZE, + "bpf_load: can't mknod %s: %s", + buf, pcap_strerror(errno)); + return (-1); + } + } + } + + /* Check if the driver is loaded */ + memset(&cfg_ld, 0x0, sizeof(cfg_ld)); + cfg_ld.path = buf; + sprintf(cfg_ld.path, "%s/%s", DRIVER_PATH, BPF_NAME); + if ((sysconfig(SYS_QUERYLOAD, (void *)&cfg_ld, sizeof(cfg_ld)) == -1) || + (cfg_ld.kmid == 0)) { + /* Driver isn't loaded, load it now */ + if (sysconfig(SYS_SINGLELOAD, (void *)&cfg_ld, sizeof(cfg_ld)) == -1) { + snprintf(errbuf, PCAP_ERRBUF_SIZE, + "bpf_load: could not load driver: %s", + strerror(errno)); + return (-1); + } + } + + /* Configure the driver */ + cfg_km.cmd = CFG_INIT; + cfg_km.kmid = cfg_ld.kmid; + cfg_km.mdilen = sizeof(cfg_bpf); + cfg_km.mdiptr = (void *)&cfg_bpf; + for (i = 0; i < BPF_MINORS; i++) { + cfg_bpf.devno = domakedev(major, i); + if (sysconfig(SYS_CFGKMOD, (void *)&cfg_km, sizeof(cfg_km)) == -1) { + snprintf(errbuf, PCAP_ERRBUF_SIZE, + "bpf_load: could not configure driver: %s", + strerror(errno)); + return (-1); + } + } + + bpfloadedflag = 1; + + return (0); +} +#endif + +static inline int +bpf_open(pcap_t *p, char *errbuf) +{ + int fd; +#ifdef HAVE_CLONING_BPF + static const char device[] = "/dev/bpf"; +#else + int n = 0; + char device[sizeof "/dev/bpf0000000000"]; +#endif + +#ifdef _AIX + /* + * Load the bpf driver, if it isn't already loaded, + * and create the BPF device entries, if they don't + * already exist. + */ + if (bpf_load(errbuf) == -1) + return (-1); +#endif + +#ifdef HAVE_CLONING_BPF + if ((fd = open(device, O_RDWR)) == -1 && + (errno != EACCES || (fd = open(device, O_RDONLY)) == -1)) + snprintf(errbuf, PCAP_ERRBUF_SIZE, + "(cannot open device) %s: %s", device, pcap_strerror(errno)); +#else + /* + * Go through all the minors and find one that isn't in use. + */ + do { + (void)snprintf(device, sizeof(device), "/dev/bpf%d", n++); + /* + * Initially try a read/write open (to allow the inject + * method to work). If that fails due to permission + * issues, fall back to read-only. This allows a + * non-root user to be granted specific access to pcap + * capabilities via file permissions. + * + * XXX - we should have an API that has a flag that + * controls whether to open read-only or read-write, + * so that denial of permission to send (or inability + * to send, if sending packets isn't supported on + * the device in question) can be indicated at open + * time. + */ + fd = open(device, O_RDWR); + if (fd == -1 && errno == EACCES) + fd = open(device, O_RDONLY); + } while (fd < 0 && errno == EBUSY); + + /* + * XXX better message for all minors used + */ + if (fd < 0) + snprintf(errbuf, PCAP_ERRBUF_SIZE, "(no devices found) %s: %s", + device, pcap_strerror(errno)); +#endif + + return (fd); +} + +/* + * We include the OS's <net/bpf.h>, not our "pcap-bpf.h", so we probably + * don't get DLT_DOCSIS defined. + */ +#ifndef DLT_DOCSIS +#define DLT_DOCSIS 143 +#endif + +pcap_t * +pcap_open_live(const char *device, int snaplen, int promisc, int to_ms, + char *ebuf) +{ + int fd; + struct ifreq ifr; + struct bpf_version bv; +#ifdef BIOCGDLTLIST + struct bpf_dltlist bdl; +#endif +#if defined(BIOCGHDRCMPLT) && defined(BIOCSHDRCMPLT) + u_int spoof_eth_src = 1; +#endif + u_int v; + pcap_t *p; + struct bpf_insn total_insn; + struct bpf_program total_prog; + struct utsname osinfo; + +#ifdef HAVE_DAG_API + if (strstr(device, "dag")) { + return dag_open_live(device, snaplen, promisc, to_ms, ebuf); + } +#endif /* HAVE_DAG_API */ + +#ifdef BIOCGDLTLIST + memset(&bdl, 0, sizeof(bdl)); +#endif + + p = (pcap_t *)malloc(sizeof(*p)); + if (p == NULL) { + snprintf(ebuf, PCAP_ERRBUF_SIZE, "malloc: %s", + pcap_strerror(errno)); + return (NULL); + } + memset(p, 0, sizeof(*p)); + fd = bpf_open(p, ebuf); + if (fd < 0) + goto bad; + + p->fd = fd; + p->snapshot = snaplen; + + if (ioctl(fd, BIOCVERSION, (caddr_t)&bv) < 0) { + snprintf(ebuf, PCAP_ERRBUF_SIZE, "BIOCVERSION: %s", + pcap_strerror(errno)); + goto bad; + } + if (bv.bv_major != BPF_MAJOR_VERSION || + bv.bv_minor < BPF_MINOR_VERSION) { + snprintf(ebuf, PCAP_ERRBUF_SIZE, + "kernel bpf filter out of date"); + goto bad; + } + + /* + * Try finding a good size for the buffer; 32768 may be too + * big, so keep cutting it in half until we find a size + * that works, or run out of sizes to try. If the default + * is larger, don't make it smaller. + * + * XXX - there should be a user-accessible hook to set the + * initial buffer size. + */ + if ((ioctl(fd, BIOCGBLEN, (caddr_t)&v) < 0) || v < 32768) + v = 32768; + for ( ; v != 0; v >>= 1) { + /* Ignore the return value - this is because the call fails + * on BPF systems that don't have kernel malloc. And if + * the call fails, it's no big deal, we just continue to + * use the standard buffer size. + */ + (void) ioctl(fd, BIOCSBLEN, (caddr_t)&v); + + (void)strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name)); + if (ioctl(fd, BIOCSETIF, (caddr_t)&ifr) >= 0) + break; /* that size worked; we're done */ + + if (errno != ENOBUFS) { + snprintf(ebuf, PCAP_ERRBUF_SIZE, "BIOCSETIF: %s: %s", + device, pcap_strerror(errno)); + goto bad; + } + } + + if (v == 0) { + snprintf(ebuf, PCAP_ERRBUF_SIZE, + "BIOCSBLEN: %s: No buffer size worked", device); + goto bad; + } + + /* Get the data link layer type. */ + if (ioctl(fd, BIOCGDLT, (caddr_t)&v) < 0) { + snprintf(ebuf, PCAP_ERRBUF_SIZE, "BIOCGDLT: %s", + pcap_strerror(errno)); + goto bad; + } +#ifdef _AIX + /* + * AIX's BPF returns IFF_ types, not DLT_ types, in BIOCGDLT. + */ + switch (v) { + + case IFT_ETHER: + case IFT_ISO88023: + v = DLT_EN10MB; + break; + + case IFT_FDDI: + v = DLT_FDDI; + break; + + case IFT_ISO88025: + v = DLT_IEEE802; + break; + + case IFT_LOOP: + v = DLT_NULL; + break; + + default: + /* + * We don't know what to map this to yet. + */ + snprintf(ebuf, PCAP_ERRBUF_SIZE, "unknown interface type %u", + v); + goto bad; + } +#endif +#if _BSDI_VERSION - 0 >= 199510 + /* The SLIP and PPP link layer header changed in BSD/OS 2.1 */ + switch (v) { + + case DLT_SLIP: + v = DLT_SLIP_BSDOS; + break; + + case DLT_PPP: + v = DLT_PPP_BSDOS; + break; + + case 11: /*DLT_FR*/ + v = DLT_FRELAY; + break; + + case 12: /*DLT_C_HDLC*/ + v = DLT_CHDLC; + break; + } +#endif +#ifdef PCAP_FDDIPAD + if (v == DLT_FDDI) + p->fddipad = PCAP_FDDIPAD; + else + p->fddipad = 0; +#endif + p->linktype = v; + +#ifdef BIOCGDLTLIST + /* + * We know the default link type -- now determine all the DLTs + * this interface supports. If this fails with EINVAL, it's + * not fatal; we just don't get to use the feature later. + */ + if (ioctl(fd, BIOCGDLTLIST, (caddr_t)&bdl) == 0) { + u_int i; + int is_ethernet; + + bdl.bfl_list = (u_int *) malloc(sizeof(u_int) * (bdl.bfl_len + 1)); + if (bdl.bfl_list == NULL) { + (void)snprintf(ebuf, PCAP_ERRBUF_SIZE, "malloc: %s", + pcap_strerror(errno)); + goto bad; + } + + if (ioctl(fd, BIOCGDLTLIST, (caddr_t)&bdl) < 0) { + (void)snprintf(ebuf, PCAP_ERRBUF_SIZE, + "BIOCGDLTLIST: %s", pcap_strerror(errno)); + free(bdl.bfl_list); + goto bad; + } + + /* + * OK, for real Ethernet devices, add DLT_DOCSIS to the + * list, so that an application can let you choose it, + * in case you're capturing DOCSIS traffic that a Cisco + * Cable Modem Termination System is putting out onto + * an Ethernet (it doesn't put an Ethernet header onto + * the wire, it puts raw DOCSIS frames out on the wire + * inside the low-level Ethernet framing). + * + * A "real Ethernet device" is defined here as a device + * that has a link-layer type of DLT_EN10MB and that has + * no alternate link-layer types; that's done to exclude + * 802.11 interfaces (which might or might not be the + * right thing to do, but I suspect it is - Ethernet <-> + * 802.11 bridges would probably badly mishandle frames + * that don't have Ethernet headers). + */ + if (p->linktype == DLT_EN10MB) { + is_ethernet = 1; + for (i = 0; i < bdl.bfl_len; i++) { + if (bdl.bfl_list[i] != DLT_EN10MB) { + is_ethernet = 0; + break; + } + } + if (is_ethernet) { + /* + * We reserved one more slot at the end of + * the list. + */ + bdl.bfl_list[bdl.bfl_len] = DLT_DOCSIS; + bdl.bfl_len++; + } + } + p->dlt_count = bdl.bfl_len; + p->dlt_list = bdl.bfl_list; + } else { + if (errno != EINVAL) { + (void)snprintf(ebuf, PCAP_ERRBUF_SIZE, + "BIOCGDLTLIST: %s", pcap_strerror(errno)); + goto bad; + } + } +#endif + + /* + * If this is an Ethernet device, and we don't have a DLT_ list, + * give it a list with DLT_EN10MB and DLT_DOCSIS. (That'd give + * 802.11 interfaces DLT_DOCSIS, which isn't the right thing to + * do, but there's not much we can do about that without finding + * some other way of determining whether it's an Ethernet or 802.11 + * device.) + */ + if (p->linktype == DLT_EN10MB && p->dlt_count == 0) { + p->dlt_list = (u_int *) malloc(sizeof(u_int) * 2); + /* + * If that fails, just leave the list empty. + */ + if (p->dlt_list != NULL) { + p->dlt_list[0] = DLT_EN10MB; + p->dlt_list[1] = DLT_DOCSIS; + p->dlt_count = 2; + } + } + +#if defined(BIOCGHDRCMPLT) && defined(BIOCSHDRCMPLT) + /* + * Do a BIOCSHDRCMPLT, if defined, to turn that flag on, so + * the link-layer source address isn't forcibly overwritten. + * (Should we ignore errors? Should we do this only if + * we're open for writing?) + * + * XXX - I seem to remember some packet-sending bug in some + * BSDs - check CVS log for "bpf.c"? + */ + if (ioctl(fd, BIOCSHDRCMPLT, &spoof_eth_src) == -1) { + (void)snprintf(ebuf, PCAP_ERRBUF_SIZE, + "BIOCSHDRCMPLT: %s", pcap_strerror(errno)); + goto bad; + } +#endif + /* set timeout */ + if (to_ms != 0) { + /* + * XXX - is this seconds/nanoseconds in AIX? + * (Treating it as such doesn't fix the timeout + * problem described below.) + */ + struct timeval to; + to.tv_sec = to_ms / 1000; + to.tv_usec = (to_ms * 1000) % 1000000; + if (ioctl(p->fd, BIOCSRTIMEOUT, (caddr_t)&to) < 0) { + snprintf(ebuf, PCAP_ERRBUF_SIZE, "BIOCSRTIMEOUT: %s", + pcap_strerror(errno)); + goto bad; + } + } + +#ifdef _AIX +#ifdef BIOCIMMEDIATE + /* + * Darren Reed notes that + * + * On AIX (4.2 at least), if BIOCIMMEDIATE is not set, the + * timeout appears to be ignored and it waits until the buffer + * is filled before returning. The result of not having it + * set is almost worse than useless if your BPF filter + * is reducing things to only a few packets (i.e. one every + * second or so). + * + * so we turn BIOCIMMEDIATE mode on if this is AIX. + * + * We don't turn it on for other platforms, as that means we + * get woken up for every packet, which may not be what we want; + * in the Winter 1993 USENIX paper on BPF, they say: + * + * Since a process might want to look at every packet on a + * network and the time between packets can be only a few + * microseconds, it is not possible to do a read system call + * per packet and BPF must collect the data from several + * packets and return it as a unit when the monitoring + * application does a read. + * + * which I infer is the reason for the timeout - it means we + * wait that amount of time, in the hopes that more packets + * will arrive and we'll get them all with one read. + * + * Setting BIOCIMMEDIATE mode on FreeBSD (and probably other + * BSDs) causes the timeout to be ignored. + * + * On the other hand, some platforms (e.g., Linux) don't support + * timeouts, they just hand stuff to you as soon as it arrives; + * if that doesn't cause a problem on those platforms, it may + * be OK to have BIOCIMMEDIATE mode on BSD as well. + * + * (Note, though, that applications may depend on the read + * completing, even if no packets have arrived, when the timeout + * expires, e.g. GUI applications that have to check for input + * while waiting for packets to arrive; a non-zero timeout + * prevents "select()" from working right on FreeBSD and + * possibly other BSDs, as the timer doesn't start until a + * "read()" is done, so the timer isn't in effect if the + * application is blocked on a "select()", and the "select()" + * doesn't get woken up for a BPF device until the buffer + * fills up.) + */ + v = 1; + if (ioctl(p->fd, BIOCIMMEDIATE, &v) < 0) { + snprintf(ebuf, PCAP_ERRBUF_SIZE, "BIOCIMMEDIATE: %s", + pcap_strerror(errno)); + goto bad; + } +#endif /* BIOCIMMEDIATE */ +#endif /* _AIX */ + + if (promisc) { + /* set promiscuous mode, okay if it fails */ + if (ioctl(p->fd, BIOCPROMISC, NULL) < 0) { + snprintf(ebuf, PCAP_ERRBUF_SIZE, "BIOCPROMISC: %s", + pcap_strerror(errno)); + } + } + + if (ioctl(fd, BIOCGBLEN, (caddr_t)&v) < 0) { + snprintf(ebuf, PCAP_ERRBUF_SIZE, "BIOCGBLEN: %s", + pcap_strerror(errno)); + goto bad; + } + p->bufsize = v; + p->buffer = (u_char *)malloc(p->bufsize); + if (p->buffer == NULL) { + snprintf(ebuf, PCAP_ERRBUF_SIZE, "malloc: %s", + pcap_strerror(errno)); + goto bad; + } +#ifdef _AIX + /* For some strange reason this seems to prevent the EFAULT + * problems we have experienced from AIX BPF. */ + memset(p->buffer, 0x0, p->bufsize); +#endif + + /* + * If there's no filter program installed, there's + * no indication to the kernel of what the snapshot + * length should be, so no snapshotting is done. + * + * Therefore, when we open the device, we install + * an "accept everything" filter with the specified + * snapshot length. + */ + total_insn.code = (u_short)(BPF_RET | BPF_K); + total_insn.jt = 0; + total_insn.jf = 0; + total_insn.k = snaplen; + + total_prog.bf_len = 1; + total_prog.bf_insns = &total_insn; + if (ioctl(p->fd, BIOCSETF, (caddr_t)&total_prog) < 0) { + snprintf(ebuf, PCAP_ERRBUF_SIZE, "BIOCSETF: %s", + pcap_strerror(errno)); + goto bad; + } + + /* + * On most BPF platforms, either you can do a "select()" or + * "poll()" on a BPF file descriptor and it works correctly, + * or you can do it and it will return "readable" if the + * hold buffer is full but not if the timeout expires *and* + * a non-blocking read will, if the hold buffer is empty + * but the store buffer isn't empty, rotate the buffers + * and return what packets are available. + * + * In the latter case, the fact that a non-blocking read + * will give you the available packets means you can work + * around the failure of "select()" and "poll()" to wake up + * and return "readable" when the timeout expires by using + * the timeout as the "select()" or "poll()" timeout, putting + * the BPF descriptor into non-blocking mode, and read from + * it regardless of whether "select()" reports it as readable + * or not. + * + * However, in FreeBSD 4.3 and 4.4, "select()" and "poll()" + * won't wake up and return "readable" if the timer expires + * and non-blocking reads return EWOULDBLOCK if the hold + * buffer is empty, even if the store buffer is non-empty. + * + * This means the workaround in question won't work. + * + * Therefore, on FreeBSD 4.3 and 4.4, we set "p->selectable_fd" + * to -1, which means "sorry, you can't use 'select()' or 'poll()' + * here". On all other BPF platforms, we set it to the FD for + * the BPF device; in NetBSD, OpenBSD, and Darwin, a non-blocking + * read will, if the hold buffer is empty and the store buffer + * isn't empty, rotate the buffers and return what packets are + * there (and in sufficiently recent versions of OpenBSD + * "select()" and "poll()" should work correctly). + * + * XXX - what about AIX? + */ + p->selectable_fd = p->fd; /* assume select() works until we know otherwise */ + if (uname(&osinfo) == 0) { + /* + * We can check what OS this is. + */ + if (strcmp(osinfo.sysname, "FreeBSD") == 0) { + if (strncmp(osinfo.release, "4.3-", 4) == 0 || + strncmp(osinfo.release, "4.4-", 4) == 0) + p->selectable_fd = -1; + } + } + + p->read_op = pcap_read_bpf; + p->inject_op = pcap_inject_bpf; + p->setfilter_op = pcap_setfilter_bpf; + p->setdirection_op = pcap_setdirection_bpf; + p->set_datalink_op = pcap_set_datalink_bpf; + p->getnonblock_op = pcap_getnonblock_fd; + p->setnonblock_op = pcap_setnonblock_fd; + p->stats_op = pcap_stats_bpf; + p->close_op = pcap_close_common; + + return (p); + bad: + (void)close(fd); + if (p->dlt_list != NULL) + free(p->dlt_list); + free(p); + return (NULL); +} + +int +pcap_platform_finddevs(pcap_if_t **alldevsp, char *errbuf) +{ +#ifdef HAVE_DAG_API + if (dag_platform_finddevs(alldevsp, errbuf) < 0) + return (-1); +#endif /* HAVE_DAG_API */ + + return (0); +} + +static int +pcap_setfilter_bpf(pcap_t *p, struct bpf_program *fp) +{ + /* + * It looks that BPF code generated by gen_protochain() is not + * compatible with some of kernel BPF code (for example BSD/OS 3.1). + * Take a safer side for now. + */ + if (no_optimize) { + /* + * XXX - what if we already have a filter in the kernel? + */ + if (install_bpf_program(p, fp) < 0) + return (-1); + p->md.use_bpf = 0; /* filtering in userland */ + return (0); + } + + /* + * Free any user-mode filter we might happen to have installed. + */ + pcap_freecode(&p->fcode); + + /* + * Try to install the kernel filter. + */ + if (ioctl(p->fd, BIOCSETF, (caddr_t)fp) < 0) { + snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "BIOCSETF: %s", + pcap_strerror(errno)); + return (-1); + } + p->md.use_bpf = 1; /* filtering in the kernel */ + + /* + * Discard any previously-received packets, as they might have + * passed whatever filter was formerly in effect, but might + * not pass this filter (BIOCSETF discards packets buffered + * in the kernel, so you can lose packets in any case). + */ + p->cc = 0; + return (0); +} + +/* + * Set direction flag: Which packets do we accept on a forwarding + * single device? IN, OUT or both? + */ +static int +pcap_setdirection_bpf(pcap_t *p, pcap_direction_t d) +{ +#if defined(BIOCSDIRECTION) + u_int direction; + + direction = (d == PCAP_D_IN) ? BPF_D_IN : + ((d == PCAP_D_OUT) ? BPF_D_OUT : BPF_D_INOUT); + if (ioctl(p->fd, BIOCSDIRECTION, &direction) == -1) { + (void) snprintf(p->errbuf, sizeof(p->errbuf), + "Cannot set direction to %s: %s", + (d == PCAP_D_IN) ? "PCAP_D_IN" : + ((d == PCAP_D_OUT) ? "PCAP_D_OUT" : "PCAP_D_INOUT"), + strerror(errno)); + return (-1); + } + return (0); +#elif defined(BIOCSSEESENT) + u_int seesent; + + /* + * We don't support PCAP_D_OUT. + */ + if (d == PCAP_D_OUT) { + snprintf(p->errbuf, sizeof(p->errbuf), + "Setting direction to PCAP_D_OUT is not supported on BPF"); + return -1; + } + + seesent = (d == PCAP_D_INOUT); + if (ioctl(p->fd, BIOCSSEESENT, &seesent) == -1) { + (void) snprintf(p->errbuf, sizeof(p->errbuf), + "Cannot set direction to %s: %s", + (d == PCAP_D_INOUT) ? "PCAP_D_INOUT" : "PCAP_D_IN", + strerror(errno)); + return (-1); + } + return (0); +#else + (void) snprintf(p->errbuf, sizeof(p->errbuf), + "This system doesn't support BIOCSSEESENT, so the direction can't be set"); + return (-1); +#endif +} + +static int +pcap_set_datalink_bpf(pcap_t *p, int dlt) +{ +#ifdef BIOCSDLT + if (ioctl(p->fd, BIOCSDLT, &dlt) == -1) { + (void) snprintf(p->errbuf, sizeof(p->errbuf), + "Cannot set DLT %d: %s", dlt, strerror(errno)); + return (-1); + } +#endif + return (0); +} |
