[libpcap] / testprogs / filtertest.c

/*
 * Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 2000
 *      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.
 */

#include "varattrs.h"

#ifndef lint
static const char copyright[] _U_ =
    "@(#) Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 2000\n\
The Regents of the University of California.  All rights reserved.\n";
#endif

#include <config.h>

#include <pcap.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>
#include <limits.h>
#ifdef _WIN32
  #include "getopt.h"
  #include "unix.h"
#else
  #include <unistd.h>
  #include <sysexits.h>
#endif
#include <fcntl.h>
#include <errno.h>
#ifdef _WIN32
  #include <winsock2.h>
  #include <ws2tcpip.h>
#else
  #include <sys/socket.h>
  #include <arpa/inet.h>
#endif
#include <sys/types.h>
#include <sys/stat.h>

#include "pcap/funcattrs.h"

#define MAXIMUM_SNAPLEN         262144
#define MAX_STDIN               (64 * 1024)

#ifdef BDEBUG
/*
 * We have pcap_set_optimizer_debug() and pcap_set_print_dot_graph() in
 * libpcap; declare them (they're not declared by any libpcap header,
 * because they're special hacks, only available if libpcap was configured
 * to include them, and only intended for use by libpcap developers trying
 * to debug the optimizer for filter expressions).
 */
PCAP_API void pcap_set_optimizer_debug(int);
PCAP_API void pcap_set_print_dot_graph(int);
#endif

#ifdef __linux__
#include <linux/filter.h> // SKF_AD_VLAN_TAG_PRESENT
/*
 * pcap-int.h is a private header and should not be included by programs that
 * use libpcap.  This test program uses a special hack because it is the
 * simplest way to test internal code paths that otherwise would require
 * elevated privileges.  Do not do this in normal code.
 */
#include <pcap-int.h>
#endif // __linux__

static char *program_name;

/* Forwards */
static void PCAP_NORETURN usage(FILE *);
static void PCAP_NORETURN error(const int, const char *, ...) PCAP_PRINTFLIKE(2, 3);
static void warn(const char *, ...) PCAP_PRINTFLIKE(1, 2);

/*
 * On Windows, we need to open the file in binary mode, so that
 * we get all the bytes specified by the size we get from "fstat()".
 * On UNIX, that's not necessary.  O_BINARY is defined on Windows;
 * we define it as 0 if it's not defined, so it does nothing.
 */
#ifndef O_BINARY
#define O_BINARY        0
#endif

// Replace "# comment" with spaces.
static void
blank_comments(char *cp, const size_t size)
{
        for (size_t i = 0; i < size; i++) {
                if (cp[i] == '#')
                        while (i < size && cp[i] != '\n')
                                cp[i++] = ' ';
        }
}

static char *
read_infile(char *fname)
{
        int fd, cc;
        register char *cp;
        struct stat buf;

        fd = open(fname, O_RDONLY|O_BINARY);
        if (fd < 0)
                error(EX_NOINPUT, "can't open %s: %s", fname, pcap_strerror(errno));

        if (fstat(fd, &buf) < 0)
                error(EX_NOINPUT, "can't stat %s: %s", fname, pcap_strerror(errno));

        /*
         * _read(), on Windows, has an unsigned int byte count and an
         * int return value, so we can't handle a file bigger than
         * INT_MAX - 1 bytes (and have no reason to do so; a filter *that*
         * big will take forever to compile).  (The -1 is for the '\0' at
         * the end of the string.)
         */
        if (buf.st_size > INT_MAX - 1)
                error(EX_DATAERR, "%s is larger than %d bytes; that's too large", fname,
                    INT_MAX - 1);
        cp = malloc((u_int)buf.st_size + 1);
        if (cp == NULL)
                error(EX_OSERR, "malloc(%d) for %s: %s", (u_int)buf.st_size + 1,
                        fname, pcap_strerror(errno));
        cc = (int)read(fd, cp, (u_int)buf.st_size);
        if (cc < 0)
                error(EX_IOERR, "read %s: %s", fname, pcap_strerror(errno));
        if (cc != buf.st_size)
                error(EX_IOERR, "short read %s (%d != %d)", fname, cc, (int)buf.st_size);

        close(fd);
        blank_comments(cp, (size_t)cc);
        cp[cc] = '\0';
        return (cp);
}

// Copy stdin into a size-limited buffer.
static char *
read_stdin(void)
{
        char *buf = calloc(1, MAX_STDIN + 1);
        if (buf == NULL)
                error(EX_OSERR, "%s: calloc", __func__);
        size_t readsize = fread(buf, 1, MAX_STDIN, stdin);
        if (! feof(stdin)) {
                free(buf);
                error(EX_DATAERR, "received more than %u bytes on stdin", MAX_STDIN);
        }
        if (ferror(stdin)) {
                free(buf);
                error(EX_IOERR, "failed reading from stdin after %zd bytes", readsize);
        }
        fclose(stdin);
        // No error, all data is within the buffer and NUL-terminated.
        blank_comments(buf, readsize);
        return buf;
}

/* VARARGS */
static void
error(const int status, const char *fmt, ...)
{
        va_list ap;

        (void)fprintf(stderr, "%s: ", program_name);
        va_start(ap, fmt);
        (void)vfprintf(stderr, fmt, ap);
        va_end(ap);
        if (*fmt) {
                fmt += strlen(fmt);
                if (fmt[-1] != '\n')
                        (void)fputc('\n', stderr);
        }
        exit(status);
        /* NOTREACHED */
}

/* VARARGS */
static void
warn(const char *fmt, ...)
{
        va_list ap;

        (void)fprintf(stderr, "%s: WARNING: ", program_name);
        va_start(ap, fmt);
        (void)vfprintf(stderr, fmt, ap);
        va_end(ap);
        if (*fmt) {
                fmt += strlen(fmt);
                if (fmt[-1] != '\n')
                        (void)fputc('\n', stderr);
        }
}

/*
 * Copy arg vector into a new buffer, concatenating arguments with spaces.
 */
static char *
copy_argv(register char **argv)
{
        register char **p;
        register size_t len = 0;
        char *buf;
        char *src, *dst;

        p = argv;
        if (*p == 0)
                return 0;

        while (*p)
                len += strlen(*p++) + 1;

        buf = (char *)malloc(len);
        if (buf == NULL)
                error(EX_OSERR, "%s: malloc", __func__);

        p = argv;
        dst = buf;
        while ((src = *p++) != NULL) {
                while ((*dst++ = *src++) != '\0')
                        ;
                dst[-1] = ' ';
        }
        dst[-1] = '\0';

        return buf;
}

int
main(int argc, char **argv)
{
        char *cp;
        int op;
        int dflag = 1;
#ifdef BDEBUG
        int gflag = 0;
#endif
        char *infile = NULL;
        char *insavefile = NULL;
        int Oflag = 1;
#ifdef __linux__
        int lflag = 0;
#endif
        int snaplen = MAXIMUM_SNAPLEN;
        char *p;
        bpf_u_int32 netmask = PCAP_NETMASK_UNKNOWN;
        char *cmdbuf;
        pcap_t *pd;
        struct bpf_program fcode;

#ifdef _WIN32
        WSADATA wsaData;
        if (0 != WSAStartup(MAKEWORD(2, 2), &wsaData))
                return 1;
#endif /* _WIN32 */

        if ((cp = strrchr(argv[0], '/')) != NULL)
                program_name = cp + 1;
        else
                program_name = argv[0];

        opterr = 0;
        while ((op = getopt(argc, argv, "hdF:gm:Os:lr:")) != -1) {
                switch (op) {

                case 'h':
                        usage(stdout);
                        /* NOTREACHED */

                case 'd':
                        ++dflag;
                        break;

                case 'g':
#ifdef BDEBUG
                        ++gflag;
                        break;
#else
                        error(EX_USAGE, "libpcap and filtertest not built with optimizer debugging enabled");
#endif

                case 'F':
                        infile = optarg;
                        break;

                case 'r':
                        insavefile = optarg;
                        break;

                case 'O':
                        Oflag = 0;
                        break;

                case 'm': {
                        bpf_u_int32 addr;

                        switch (inet_pton(AF_INET, optarg, &addr)) {

                        case 0:
                                error(EX_DATAERR, "invalid netmask %s", optarg);

                        case -1:
                                error(EX_DATAERR, "invalid netmask %s: %s", optarg,
                                    pcap_strerror(errno));

                        case 1:
                                // inet_pton(): network byte order, pcap_compile(): host byte order.
                                netmask = ntohl(addr);
                                break;
                        }
                        break;
                }

                case 's': {
                        char *end;
                        long long_snaplen;

                        long_snaplen = strtol(optarg, &end, 0);
                        if (optarg == end || *end != '\0'
                            || long_snaplen < 0
                            || long_snaplen > MAXIMUM_SNAPLEN)
                                error(EX_DATAERR, "invalid snaplen %s", optarg);
                        else {
                                if (snaplen == 0)
                                        snaplen = MAXIMUM_SNAPLEN;
                                else
                                        snaplen = (int)long_snaplen;
                        }
                        break;
                }

                case 'l':
#ifdef __linux__
                        // Enable Linux BPF extensions.
                        lflag = 1;
                        break;
#else
                        error(EX_USAGE, "libpcap and filtertest built without Linux BPF extensions");
#endif

                default:
                        usage(stderr);
                        /* NOTREACHED */
                }
        }

        if (insavefile) {
                if (dflag > 1)
                        warn("-d is a no-op with -r");
#ifdef BDEBUG
                if (gflag)
                        warn("-g is a no-op with -r");
#endif
#ifdef __linux__
                if (lflag)
                        warn("-l is a no-op with -r");
#endif

                char errbuf[PCAP_ERRBUF_SIZE];
                if (NULL == (pd = pcap_open_offline(insavefile, errbuf)))
                        error(EX_NOINPUT, "Failed opening: %s", errbuf);
        } else {
                // Must have at least one command-line argument for the DLT.
                if (optind >= argc) {
                        usage(stderr);
                        /* NOTREACHED */
                }
                int dlt = pcap_datalink_name_to_val(argv[optind]);
                if (dlt < 0) {
                        dlt = (int)strtol(argv[optind], &p, 10);
                        if (p == argv[optind] || *p != '\0')
                                error(EX_DATAERR, "invalid data link type %s", argv[optind]);
                }
                optind++;

                pd = pcap_open_dead(dlt, snaplen);
                if (pd == NULL)
                        error(EX_SOFTWARE, "Can't open fake pcap_t");
#ifdef __linux__
                if (lflag) {
#ifdef SKF_AD_VLAN_TAG_PRESENT
                        /*
                         * Generally speaking, the fact the header defines the
                         * symbol does not necessarily mean the running kernel
                         * supports what is known as [vlanp] and everything
                         * before it, but in this use case the filter program
                         * is not meant for the kernel.
                         */
                        pd->bpf_codegen_flags |= BPF_SPECIAL_VLAN_HANDLING;
#endif // SKF_AD_VLAN_TAG_PRESENT
                        pd->bpf_codegen_flags |= BPF_SPECIAL_BASIC_HANDLING;
                }
#endif // __linux__
#ifdef BDEBUG
                pcap_set_optimizer_debug(dflag);
                pcap_set_print_dot_graph(gflag);
#endif
        }

        if (infile)
                cmdbuf = strcmp(infile, "-") ? read_infile(infile) : read_stdin();
        else
                cmdbuf = copy_argv(&argv[optind]);

        if (pcap_compile(pd, &fcode, cmdbuf, Oflag, netmask) < 0)
                error(EX_DATAERR, "%s", pcap_geterr(pd));

        if (!bpf_validate(fcode.bf_insns, fcode.bf_len))
                warn("Filter doesn't pass validation");

        if (! insavefile) {
#ifdef BDEBUG
                // replace line feed with space
                for (cp = cmdbuf; *cp != '\0'; ++cp) {
                        if (*cp == '\r' || *cp == '\n') {
                                *cp = ' ';
                        }
                }
                // only show machine code if BDEBUG defined, since dflag > 3
                printf("machine codes for filter: %s\n", cmdbuf);
#endif
                bpf_dump(&fcode, dflag);
        } else {
                struct pcap_pkthdr *h;
                const u_char *d;
                int ret;
                while (PCAP_ERROR_BREAK != (ret = pcap_next_ex(pd, &h, &d))) {
                        if (ret == PCAP_ERROR)
                                error(EX_IOERR, "pcap_next_ex() failed: %s", pcap_geterr(pd));
                        if (ret == 1)
                                printf("%d\n", pcap_offline_filter(&fcode, h, d));
                        else
                                error(EX_IOERR, "pcap_next_ex() failed: %d", ret);
                }
        }
        free(cmdbuf);
        pcap_freecode (&fcode);
        pcap_close(pd);
#ifdef _WIN32
        WSACleanup();
#endif
        exit(EX_OK);
}

static void
usage(FILE *f)
{
        (void)fprintf(f, "%s, with %s\n", program_name,
            pcap_lib_version());
        (void)fprintf(f,
            "Usage: %s [-d"
#ifdef BDEBUG
            "g"
#endif
            "O"
#ifdef __linux__
            "l"
#endif
            "] [ -F file ] [ -m netmask] [ -s snaplen ] dlt [ expr ]\n",
            program_name);
        (void)fprintf(f, "       (print the filter program bytecode)\n");
        (void)fprintf(f,
            "  or:  %s [-O] [ -F file ] [ -m netmask] -r file [ expression ]\n",
            program_name);
        (void)fprintf(f, "       (print the filter program result for each packet)\n");
        (void)fprintf(f, "  or:  %s -h\n", program_name);
        (void)fprintf(f, "       (print the detailed help screen)\n");
        if (f == stdout) {
                (void)fprintf(f, "\nOptions specific to %s:\n", program_name);
                (void)fprintf(f, "  <dlt>           a valid DLT name, e.g. 'EN10MB'\n");
                (void)fprintf(f, "  <expr>          a valid filter expression, e.g. 'tcp port 80'\n");
#ifdef __linux__
                (void)fprintf(f, "  -l              allow the use of Linux BPF extensions\n");
#endif
#ifdef BDEBUG
                (void)fprintf(f, "  -g              print Graphviz dot graphs for the optimizer steps\n");
#endif
                (void)fprintf(f, "  -m <netmask>    use this netmask for pcap_compile(), e.g. 255.255.255.0\n");
                (void)fprintf(f, "\n");
                (void)fprintf(f, "Options common with tcpdump:\n");
                (void)fprintf(f, "  -d              change output format (accumulates, one -d is implicit)\n");
                (void)fprintf(f, "  -O              do not optimize the filter program\n");
                (void)fprintf(f, "  -F <file>       read the filter expression from the specified file\n");
                (void)fprintf(f, "                  (\"-\" means stdin and allows at most %u characters)\n", MAX_STDIN);
                (void)fprintf(f, "  -s <snaplen>    set the snapshot length\n");
                (void)fprintf(f, "  -r <file>       read the packets from this savefile\n");
                (void)fprintf(f, "\nIf no filter expression is specified, it defaults to an empty string, which\n");
                (void)fprintf(f, "accepts all packets.  If the -F option is in use, it replaces any filter\n");
                (void)fprintf(f, "expression specified as a command-line argument.\n");
        }
        exit(f == stdout ? EX_OK : EX_USAGE);
}