fad-helpers.c

/* -*- Mode: c; tab-width: 8; indent-tabs-mode: 1; c-basic-offset: 8; -*- */
/*
 * Copyright (c) 1994, 1995, 1996, 1997, 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 the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the Computer Systems
 *	Engineering Group at Lawrence Berkeley Laboratory.
 * 4. Neither the name of the University nor of the Laboratory may be used
 *    to endorse or promote products derived from this software without
 *    specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#ifdef _WIN32
#include <pcap-stdinc.h>
#else /* _WIN32 */

#include <sys/param.h>
#ifndef MSDOS
#include <sys/file.h>
#endif
#include <sys/ioctl.h>
#include <sys/socket.h>
#ifdef HAVE_SYS_SOCKIO_H
#include <sys/sockio.h>
#endif

struct mbuf;		/* Squelch compiler warnings on some platforms for */
struct rtentry;		/* declarations in <net/if.h> */
#include <net/if.h>
#include <netinet/in.h>
#endif /* _WIN32 */

#include <ctype.h>
#include <errno.h>
#include <memory.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#if !defined(_WIN32) && !defined(__BORLANDC__)
#include <unistd.h>
#endif /* !_WIN32 && !__BORLANDC__ */
#ifdef HAVE_LIMITS_H
#include <limits.h>
#else
#define INT_MAX		2147483647
#endif

#include "pcap-int.h"

#ifdef HAVE_OS_PROTO_H
#include "os-proto.h"
#endif

#ifndef _WIN32
/* Not all systems have IFF_LOOPBACK */
#ifdef IFF_LOOPBACK
#define ISLOOPBACK(name, flags) ((flags) & IFF_LOOPBACK)
#else
#define ISLOOPBACK(name, flags) ((name)[0] == 'l' && (name)[1] == 'o' && \
    (isdigit((unsigned char)((name)[2])) || (name)[2] == '\0'))
#endif

#ifdef IFF_UP
#define ISUP(flags) ((flags) & IFF_UP)
#else
#define ISUP(flags) 0
#endif

#ifdef IFF_RUNNING
#define ISRUNNING(flags) ((flags) & IFF_RUNNING)
#else
#define ISRUNNING(flags) 0
#endif

/*
 * Map UN*X-style interface flags to libpcap flags.
 */
bpf_u_int32
if_flags_to_pcap_flags(const char *name _U_, u_int if_flags)
{
	bpf_u_int32 pcap_flags;

	pcap_flags = 0;
	if (ISLOOPBACK(name, if_flags))
		pcap_flags |= PCAP_IF_LOOPBACK;
	if (ISUP(if_flags))
		pcap_flags |= PCAP_IF_UP;
	if (ISRUNNING(if_flags))
		pcap_flags |= PCAP_IF_RUNNING;
	return (pcap_flags);
}
#endif

static struct sockaddr *
dup_sockaddr(struct sockaddr *sa, size_t sa_length)
{
	struct sockaddr *newsa;

	if ((newsa = malloc(sa_length)) == NULL)
		return (NULL);
	return (memcpy(newsa, sa, sa_length));
}

/*
 * Construct a "figure of merit" for an interface, for use when sorting
 * the list of interfaces, in which interfaces that are up are superior
 * to interfaces that aren't up, interfaces that are up and running are
 * superior to interfaces that are up but not running, and non-loopback
 * interfaces that are up and running are superior to loopback interfaces,
 * and interfaces with the same flags have a figure of merit that's higher
 * the lower the instance number.
 *
 * The goal is to try to put the interfaces most likely to be useful for
 * capture at the beginning of the list.
 *
 * The figure of merit, which is lower the "better" the interface is,
 * has the uppermost bit set if the interface isn't running, the bit
 * below that set if the interface isn't up, the bit below that set
 * if the interface is a loopback interface, and the interface index
 * in the 29 bits below that.  (Yes, we assume u_int is 32 bits.)
 */
static u_int
get_figure_of_merit(pcap_if_t *dev)
{
	const char *cp;
	u_int n;

	if (strcmp(dev->name, "any") == 0) {
		/*
		 * Give the "any" device an artificially high instance
		 * number, so it shows up after all other non-loopback
		 * interfaces.
		 */
		n = 0x1FFFFFFF;	/* 29 all-1 bits */
	} else {
		/*
		 * A number at the end of the device name string is
		 * assumed to be an instance number.  Add 1 to the
		 * instance number, and use 0 for "no instance
		 * number", so we don't put "no instance number"
		 * devices and "instance 0" devices together.
		 */
		cp = dev->name + strlen(dev->name) - 1;
		while (cp-1 >= dev->name && *(cp-1) >= '0' && *(cp-1) <= '9')
			cp--;
		if (*cp >= '0' && *cp <= '9')
			n = atoi(cp) + 1;
		else
			n = 0;
	}
	if (!(dev->flags & PCAP_IF_RUNNING))
		n |= 0x80000000;
	if (!(dev->flags & PCAP_IF_UP))
		n |= 0x40000000;
	if (dev->flags & PCAP_IF_LOOPBACK)
		n |= 0x20000000;
	return (n);
}

#ifndef _WIN32
/*
 * Try to get a description for a given device.
 * Returns a mallocated description if it could and NULL if it couldn't.
 *
 * XXX - on FreeBSDs that support it, should it get the sysctl named
 * "dev.{adapter family name}.{adapter unit}.%desc" to get a description
 * of the adapter?  Note that "dev.an.0.%desc" is "Aironet PC4500/PC4800"
 * with my Cisco 350 card, so the name isn't entirely descriptive.  The
 * "dev.an.0.%pnpinfo" has a better description, although one might argue
 * that the problem is really a driver bug - if it can find out that it's
 * a Cisco 340 or 350, rather than an old Aironet card, it should use
 * that in the description.
 *
 * Do NetBSD, DragonflyBSD, or OpenBSD support this as well?  FreeBSD
 * and OpenBSD let you get a description, but it's not generated by the OS,
 * it's set with another ioctl that ifconfig supports; we use that to get
 * a description in FreeBSD and OpenBSD, but if there is no such
 * description available, it still might be nice to get some description
 * string based on the device type or something such as that.
 *
 * In OS X, the System Configuration framework can apparently return
 * names in 10.4 and later.
 *
 * It also appears that freedesktop.org's HAL offers an "info.product"
 * string, but the HAL specification says it "should not be used in any
 * UI" and "subsystem/capability specific properties" should be used
 * instead and, in any case, I think HAL is being deprecated in
 * favor of other stuff such as DeviceKit.  DeviceKit doesn't appear
 * to have any obvious product information for devices, but maybe
 * I haven't looked hard enough.
 *
 * Using the System Configuration framework, or HAL, or DeviceKit, or
 * whatever, would require that libpcap applications be linked with
 * the frameworks/libraries in question.  That shouldn't be a problem
 * for programs linking with the shared version of libpcap (unless
 * you're running on AIX - which I think is the only UN*X that doesn't
 * support linking a shared library with other libraries on which it
 * depends, and having an executable linked only with the first shared
 * library automatically pick up the other libraries when started -
 * and using HAL or whatever).  Programs linked with the static
 * version of libpcap would have to use pcap-config with the --static
 * flag in order to get the right linker flags in order to pick up
 * the additional libraries/frameworks; those programs need that anyway
 * for libpcap 1.1 and beyond on Linux, as, by default, it requires
 * -lnl.
 *
 * Do any other UN*Xes, or desktop environments support getting a
 * description?
 */
static char *
get_if_description(const char *name)
{
#ifdef SIOCGIFDESCR
	char *description = NULL;
	int s;
	struct ifreq ifrdesc;
#ifndef IFDESCRSIZE
	size_t descrlen = 64;
#else
	size_t descrlen = IFDESCRSIZE;
#endif /* IFDESCRSIZE */

	/*
	 * Get the description for the interface.
	 */
	memset(&ifrdesc, 0, sizeof ifrdesc);
	strlcpy(ifrdesc.ifr_name, name, sizeof ifrdesc.ifr_name);
	s = socket(AF_INET, SOCK_DGRAM, 0);
	if (s >= 0) {
#ifdef __FreeBSD__
		/*
		 * On FreeBSD, if the buffer isn't big enough for the
		 * description, the ioctl succeeds, but the description
		 * isn't copied, ifr_buffer.length is set to the description
		 * length, and ifr_buffer.buffer is set to NULL.
		 */
		for (;;) {
			free(description);
			if ((description = malloc(descrlen)) != NULL) {
				ifrdesc.ifr_buffer.buffer = description;
				ifrdesc.ifr_buffer.length = descrlen;
				if (ioctl(s, SIOCGIFDESCR, &ifrdesc) == 0) {
					if (ifrdesc.ifr_buffer.buffer ==
					    description)
						break;
					else
						descrlen = ifrdesc.ifr_buffer.length;
				} else {
					/*
					 * Failed to get interface description.
					 */
					free(description);
					description = NULL;
					break;
				}
			} else
				break;
		}
#else /* __FreeBSD__ */
		/*
		 * The only other OS that currently supports
		 * SIOCGIFDESCR is OpenBSD, and it has no way
		 * to get the description length - it's clamped
		 * to a maximum of IFDESCRSIZE.
		 */
		if ((description = malloc(descrlen)) != NULL) {
			ifrdesc.ifr_data = (caddr_t)description;
			if (ioctl(s, SIOCGIFDESCR, &ifrdesc) != 0) {
				/*
				 * Failed to get interface description.
				 */
				free(description);
				description = NULL;
			}
		}
#endif /* __FreeBSD__ */
		close(s);
		if (description != NULL && strlen(description) == 0) {
			/*
			 * Description is empty, so discard it.
			 */
			free(description);
			description = NULL;
		}
	}

#ifdef __FreeBSD__
	/*
	 * For FreeBSD, if we didn't get a description, and this is
	 * a device with a name of the form usbusN, label it as a USB
	 * bus.
	 */
	if (description == NULL) {
		if (strncmp(name, "usbus", 5) == 0) {
			/*
			 * OK, it begins with "usbus".
			 */
			long busnum;
			char *p;

			errno = 0;
			busnum = strtol(name + 5, &p, 10);
			if (errno == 0 && p != name + 5 && *p == '\0' &&
			    busnum >= 0 && busnum <= INT_MAX) {
				/*
				 * OK, it's a valid number that's not
				 * bigger than INT_MAX.  Construct
				 * a description from it.
				 */
				static const char descr_prefix[] = "USB bus number ";
				size_t descr_size;

				/*
				 * Allow enough room for a 32-bit bus number.
				 * sizeof (descr_prefix) includes the
				 * terminating NUL.
				 */
				descr_size = sizeof (descr_prefix) + 10;
				description = malloc(descr_size);
				if (description != NULL) {
					pcap_snprintf(description, descr_size,
					    "%s%ld", descr_prefix, busnum);
				}
			}
		}
	}
#endif
	return (description);
#else /* SIOCGIFDESCR */
	return (NULL);
#endif /* SIOCGIFDESCR */
}

/*
 * Look for a given device in the specified list of devices.
 *
 * If we find it, then, if the specified address isn't null, add it to
 * the list of addresses for the device and return 0.
 *
 * If we don't find it, attempt to add an entry for it, with the specified
 * flags and description, and, if that succeeds, add the specified
 * address to its list of addresses if that address is non-null, and
 * return 0, otherwise return -1 and set errbuf to an error message.
 *
 * (We can get called with a null address because we might get a list
 * of interface name/address combinations from the underlying OS, with
 * the address being absent in some cases, rather than a list of
 * interfaces with each interface having a list of addresses, so this
 * call may be the only call made to add to the list, and we want to
 * add interfaces even if they have no addresses.)
 */
int
add_addr_to_iflist(pcap_if_t **alldevs, const char *name, bpf_u_int32 flags,
    struct sockaddr *addr, size_t addr_size,
    struct sockaddr *netmask, size_t netmask_size,
    struct sockaddr *broadaddr, size_t broadaddr_size,
    struct sockaddr *dstaddr, size_t dstaddr_size,
    char *errbuf)
{
	pcap_if_t *curdev;

	/*
	 * Attempt to find an entry for this device; if we don't find one,
	 * attempt to add one.
	 */
	curdev = find_or_add_dev(alldevs, name, flags, get_if_description(name),
	    errbuf);
	if (curdev == NULL) {
		/*
		 * Error - give up.
		 */
		return (-1);
	}

	if (addr == NULL) {
		/*
		 * There's no address to add; this entry just meant
		 * "here's a new interface".
		 */
		return (0);
	}

	/*
	 * "curdev" is an entry for this interface, and we have an
	 * address for it; add an entry for that address to the
	 * interface's list of addresses.
	 *
	 * Allocate the new entry and fill it in.
	 */
	return (add_addr_to_dev(curdev, addr, addr_size, netmask,
	    netmask_size, broadaddr, broadaddr_size, dstaddr,
	    dstaddr_size, errbuf));
}
#endif /* _WIN32 */

/*
 * Add an entry to the list of addresses for an interface.
 * "curdev" is the entry for that interface.
 * If this is the first IP address added to the interface, move it
 * in the list as appropriate.
 */
int
add_addr_to_dev(pcap_if_t *curdev,
    struct sockaddr *addr, size_t addr_size,
    struct sockaddr *netmask, size_t netmask_size,
    struct sockaddr *broadaddr, size_t broadaddr_size,
    struct sockaddr *dstaddr, size_t dstaddr_size,
    char *errbuf)
{
	pcap_addr_t *curaddr, *prevaddr, *nextaddr;

	curaddr = malloc(sizeof(pcap_addr_t));
	if (curaddr == NULL) {
		(void)pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
		    "malloc: %s", pcap_strerror(errno));
		return (-1);
	}

	curaddr->next = NULL;
	if (addr != NULL) {
		curaddr->addr = dup_sockaddr(addr, addr_size);
		if (curaddr->addr == NULL) {
			(void)pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
			    "malloc: %s", pcap_strerror(errno));
			free(curaddr);
			return (-1);
		}
	} else
		curaddr->addr = NULL;

	if (netmask != NULL) {
		curaddr->netmask = dup_sockaddr(netmask, netmask_size);
		if (curaddr->netmask == NULL) {
			(void)pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
			    "malloc: %s", pcap_strerror(errno));
			if (curaddr->addr != NULL)
				free(curaddr->addr);
			free(curaddr);
			return (-1);
		}
	} else
		curaddr->netmask = NULL;

	if (broadaddr != NULL) {
		curaddr->broadaddr = dup_sockaddr(broadaddr, broadaddr_size);
		if (curaddr->broadaddr == NULL) {
			(void)pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
			    "malloc: %s", pcap_strerror(errno));
			if (curaddr->netmask != NULL)
				free(curaddr->netmask);
			if (curaddr->addr != NULL)
				free(curaddr->addr);
			free(curaddr);
			return (-1);
		}
	} else
		curaddr->broadaddr = NULL;

	if (dstaddr != NULL) {
		curaddr->dstaddr = dup_sockaddr(dstaddr, dstaddr_size);
		if (curaddr->dstaddr == NULL) {
			(void)pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
			    "malloc: %s", pcap_strerror(errno));
			if (curaddr->broadaddr != NULL)
				free(curaddr->broadaddr);
			if (curaddr->netmask != NULL)
				free(curaddr->netmask);
			if (curaddr->addr != NULL)
				free(curaddr->addr);
			free(curaddr);
			return (-1);
		}
	} else
		curaddr->dstaddr = NULL;

	/*
	 * Find the end of the list of addresses.
	 */
	for (prevaddr = curdev->addresses; prevaddr != NULL; prevaddr = nextaddr) {
		nextaddr = prevaddr->next;
		if (nextaddr == NULL) {
			/*
			 * This is the end of the list.
			 */
			break;
		}
	}

	if (prevaddr == NULL) {
		/*
		 * The list was empty; this is the first member.
		 */
		curdev->addresses = curaddr;
	} else {
		/*
		 * "prevaddr" is the last member of the list; append
		 * this member to it.
		 */
		prevaddr->next = curaddr;
	}

	return (0);
}

/*
 * Look for a given device in the specified list of devices.
 *
 * If we find it, return 0 and set *curdev_ret to point to it.
 *
 * If we don't find it, attempt to add an entry for it, with the specified
 * flags and description, and, if that succeeds, return 0, otherwise
 * return -1 and set errbuf to an error message.
 */
pcap_if_t *
find_or_add_dev(pcap_if_t **alldevs, const char *name, bpf_u_int32 flags,
    const char *description, char *errbuf)
{
	pcap_if_t *curdev;

	/*
	 * Is there already an entry in the list for this interface?
	 */
	curdev = find_dev(alldevs, name);
	if (curdev != NULL) {
		/*
		 * Yes, return it.
		 */
		return (curdev);
	}

	/*
	 * No, we didn't find it.  Try to add it to the list of devices.
	 */
	return (add_dev(alldevs, name, flags, description, errbuf));
}

/*
 * Look for a given device in the specified list of devices, and return
 * the entry for it if we find it or NULL if we don't.
 */
pcap_if_t *
find_dev(pcap_if_t **alldevs, const char *name)
{
	pcap_if_t *curdev;

	/*
	 * Is there an entry in the list for this device?
	 */
	for (curdev = *alldevs; curdev != NULL; curdev = curdev->next) {
		if (strcmp(name, curdev->name) == 0) {
			/*
			 * We found it, so, yes, there is.  No need to
			 * add it.  Provide the entry we found to our
			 * caller.
			 */
			return (curdev);
		}
	}

	/*
	 * No.
	 */
	return (NULL);
}

/*
 * Attempt to add an entry for a device, with the specified flags
 * and description, and, if that succeeds, return 0 and return a pointer
 * to the new entry, otherwise return NULL and set errbuf to an error
 * message.
 *
 * If we weren't given a description, try to get one.
 */
pcap_if_t *
add_dev(pcap_if_t **alldevs, const char *name, bpf_u_int32 flags,
    const char *description, char *errbuf)
{
	pcap_if_t *curdev, *prevdev, *nextdev;
	u_int this_figure_of_merit, nextdev_figure_of_merit;

	curdev = malloc(sizeof(pcap_if_t));
	if (curdev == NULL) {
		(void)pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
		    "malloc: %s", pcap_strerror(errno));
		return (NULL);
	}

	/*
	 * Fill in the entry.
	 */
	curdev->next = NULL;
	curdev->name = strdup(name);
	if (curdev->name == NULL) {
		(void)pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
		    "malloc: %s", pcap_strerror(errno));
		free(curdev);
		return (NULL);
	}
	if (description == NULL) {
		/*
		 * We weren't handed a description for the interface.
		 */
		curdev->description = NULL;
	} else {
		/*
		 * We were handed a description; make a copy.
		 */
		curdev->description = strdup(description);
		if (curdev->description == NULL) {
			(void)pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
			    "malloc: %s", pcap_strerror(errno));
			free(curdev->name);
			free(curdev);
			return (NULL);
		}
	}
	curdev->addresses = NULL;	/* list starts out as empty */
	curdev->flags = flags;

	/*
	 * Add it to the list, in the appropriate location.
	 * First, get the "figure of merit" for this interface.
	 */
	this_figure_of_merit = get_figure_of_merit(curdev);

	/*
	 * Now look for the last interface with an figure of merit
	 * less than or equal to the new interface's figure of merit.
	 *
	 * We start with "prevdev" being NULL, meaning we're before
	 * the first element in the list.
	 */
	prevdev = NULL;
	for (;;) {
		/*
		 * Get the interface after this one.
		 */
		if (prevdev == NULL) {
			/*
			 * The next element is the first element.
			 */
			nextdev = *alldevs;
		} else
			nextdev = prevdev->next;

		/*
		 * Are we at the end of the list?
		 */
		if (nextdev == NULL) {
			/*
			 * Yes - we have to put the new entry after "prevdev".
			 */
			break;
		}

		/*
		 * Is the new interface's figure of merit less
		 * than the next interface's figure of merit,
		 * meaning that the new interface is better
		 * than the next interface?
		 */
		nextdev_figure_of_merit = get_figure_of_merit(nextdev);
		if (this_figure_of_merit < nextdev_figure_of_merit) {
			/*
			 * Yes - we should put the new entry
			 * before "nextdev", i.e. after "prevdev".
			 */
			break;
		}

		prevdev = nextdev;
	}

	/*
	 * Insert before "nextdev".
	 */
	curdev->next = nextdev;

	/*
	 * Insert after "prevdev" - unless "prevdev" is null,
	 * in which case this is the first interface.
	 */
	if (prevdev == NULL) {
		/*
		 * This is the first interface.  Pass back a
		 * pointer to it, and put "curdev" before
		 * "nextdev".
		 */
		*alldevs = curdev;
	} else
		prevdev->next = curdev;
	return (curdev);
}

/*
 * Free a list of interfaces.
 */
void
pcap_freealldevs(pcap_if_t *alldevs)
{
	pcap_if_t *curdev, *nextdev;
	pcap_addr_t *curaddr, *nextaddr;

	for (curdev = alldevs; curdev != NULL; curdev = nextdev) {
		nextdev = curdev->next;

		/*
		 * Free all addresses.
		 */
		for (curaddr = curdev->addresses; curaddr != NULL; curaddr = nextaddr) {
			nextaddr = curaddr->next;
			if (curaddr->addr)
				free(curaddr->addr);
			if (curaddr->netmask)
				free(curaddr->netmask);
			if (curaddr->broadaddr)
				free(curaddr->broadaddr);
			if (curaddr->dstaddr)
				free(curaddr->dstaddr);
			free(curaddr);
		}

		/*
		 * Free the name string.
		 */
		free(curdev->name);

		/*
		 * Free the description string, if any.
		 */
		if (curdev->description != NULL)
			free(curdev->description);

		/*
		 * Free the interface.
		 */
		free(curdev);
	}
}