kernel/modnext: Improve the flow a bit regarding setting 'error'.

[dragonfly.git] / contrib / libpcap / sf-pcap.c

/*
 * Copyright (c) 1993, 1994, 1995, 1996, 1997
 *      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.
 *
 * sf-pcap.c - libpcap-file-format-specific code from savefile.c
 *      Extraction/creation by Jeffrey Mogul, DECWRL
 *      Modified by Steve McCanne, LBL.
 *
 * Used to save the received packet headers, after filtering, to
 * a file, and then read them later.
 * The first record in the file contains saved values for the machine
 * dependent values so we can print the dump file on any architecture.
 */

#ifndef lint
static const char rcsid[] _U_ =
    "@(#) $Header$ (LBL)";
#endif

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

#ifdef WIN32
#include <pcap-stdinc.h>
#else /* WIN32 */
#if HAVE_INTTYPES_H
#include <inttypes.h>
#elif HAVE_STDINT_H
#include <stdint.h>
#endif
#ifdef HAVE_SYS_BITYPES_H
#include <sys/bitypes.h>
#endif
#include <sys/types.h>
#endif /* WIN32 */

#include <errno.h>
#include <memory.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "pcap-int.h"

#include "pcap-common.h"

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

#include "sf-pcap.h"

/*
 * Setting O_BINARY on DOS/Windows is a bit tricky
 */
#if defined(WIN32)
  #define SET_BINMODE(f)  _setmode(_fileno(f), _O_BINARY)
#elif defined(MSDOS)
  #if defined(__HIGHC__)
  #define SET_BINMODE(f)  setmode(f, O_BINARY)
  #else
  #define SET_BINMODE(f)  setmode(fileno(f), O_BINARY)
  #endif
#endif

/*
 * Standard libpcap format.
 */
#define TCPDUMP_MAGIC           0xa1b2c3d4

/*
 * Alexey Kuznetzov's modified libpcap format.
 */
#define KUZNETZOV_TCPDUMP_MAGIC 0xa1b2cd34

/*
 * Reserved for Francisco Mesquita <francisco.mesquita@radiomovel.pt>
 * for another modified format.
 */
#define FMESQUITA_TCPDUMP_MAGIC 0xa1b234cd

/*
 * Navtel Communcations' format, with nanosecond timestamps,
 * as per a request from Dumas Hwang <dumas.hwang@navtelcom.com>.
 */
#define NAVTEL_TCPDUMP_MAGIC    0xa12b3c4d

/*
 * Normal libpcap format, except for seconds/nanoseconds timestamps,
 * as per a request by Ulf Lamping <ulf.lamping@web.de>
 */
#define NSEC_TCPDUMP_MAGIC      0xa1b23c4d

/*
 * Mechanism for storing information about a capture in the upper
 * 6 bits of a linktype value in a capture file.
 *
 * LT_LINKTYPE_EXT(x) extracts the additional information.
 *
 * The rest of the bits are for a value describing the link-layer
 * value.  LT_LINKTYPE(x) extracts that value.
 */
#define LT_LINKTYPE(x)          ((x) & 0x03FFFFFF)
#define LT_LINKTYPE_EXT(x)      ((x) & 0xFC000000)

static int pcap_next_packet(pcap_t *p, struct pcap_pkthdr *hdr, u_char **datap);

/*
 * Check whether this is a pcap savefile and, if it is, extract the
 * relevant information from the header.
 */
int
pcap_check_header(pcap_t *p, bpf_u_int32 magic, FILE *fp, char *errbuf)
{
        struct pcap_file_header hdr;
        size_t amt_read;

        /*
         * Check whether the first 4 bytes of the file are the magic
         * number for a pcap savefile, or for a byte-swapped pcap
         * savefile.
         */
        if (magic != TCPDUMP_MAGIC && magic != KUZNETZOV_TCPDUMP_MAGIC) {
                magic = SWAPLONG(magic);
                if (magic != TCPDUMP_MAGIC && magic != KUZNETZOV_TCPDUMP_MAGIC)
                        return (0);     /* nope */
                p->sf.swapped = 1;
        }

        /*
         * They are.  Put the magic number in the header, and read
         * the rest of the header.
         */
        hdr.magic = magic;
        amt_read = fread(((char *)&hdr) + sizeof hdr.magic, 1,
            sizeof(hdr) - sizeof(hdr.magic), fp);
        if (amt_read != sizeof(hdr) - sizeof(hdr.magic)) {
                if (ferror(fp)) {
                        snprintf(errbuf, PCAP_ERRBUF_SIZE,
                            "error reading dump file: %s",
                            pcap_strerror(errno));
                } else {
                        snprintf(errbuf, PCAP_ERRBUF_SIZE,
                            "truncated dump file; tried to read %lu file header bytes, only got %lu",
                            (unsigned long)sizeof(hdr),
                            (unsigned long)amt_read);
                }
                return (-1);
        }

        /*
         * If it's a byte-swapped capture file, byte-swap the header.
         */
        if (p->sf.swapped) {
                hdr.version_major = SWAPSHORT(hdr.version_major);
                hdr.version_minor = SWAPSHORT(hdr.version_minor);
                hdr.thiszone = SWAPLONG(hdr.thiszone);
                hdr.sigfigs = SWAPLONG(hdr.sigfigs);
                hdr.snaplen = SWAPLONG(hdr.snaplen);
                hdr.linktype = SWAPLONG(hdr.linktype);
        }

        if (hdr.version_major < PCAP_VERSION_MAJOR) {
                snprintf(errbuf, PCAP_ERRBUF_SIZE,
                    "archaic pcap savefile format");
                return (-1);
        }
        p->sf.version_major = hdr.version_major;
        p->sf.version_minor = hdr.version_minor;
        p->tzoff = hdr.thiszone;
        p->snapshot = hdr.snaplen;
        p->linktype = linktype_to_dlt(LT_LINKTYPE(hdr.linktype));
        p->linktype_ext = LT_LINKTYPE_EXT(hdr.linktype);

        p->sf.next_packet_op = pcap_next_packet;

        /*
         * We interchanged the caplen and len fields at version 2.3,
         * in order to match the bpf header layout.  But unfortunately
         * some files were written with version 2.3 in their headers
         * but without the interchanged fields.
         *
         * In addition, DG/UX tcpdump writes out files with a version
         * number of 543.0, and with the caplen and len fields in the
         * pre-2.3 order.
         */
        switch (hdr.version_major) {

        case 2:
                if (hdr.version_minor < 3)
                        p->sf.lengths_swapped = SWAPPED;
                else if (hdr.version_minor == 3)
                        p->sf.lengths_swapped = MAYBE_SWAPPED;
                else
                        p->sf.lengths_swapped = NOT_SWAPPED;
                break;

        case 543:
                p->sf.lengths_swapped = SWAPPED;
                break;

        default:
                p->sf.lengths_swapped = NOT_SWAPPED;
                break;
        }

        if (magic == KUZNETZOV_TCPDUMP_MAGIC) {
                /*
                 * XXX - the patch that's in some versions of libpcap
                 * changes the packet header but not the magic number,
                 * and some other versions with this magic number have
                 * some extra debugging information in the packet header;
                 * we'd have to use some hacks^H^H^H^H^Hheuristics to
                 * detect those variants.
                 *
                 * Ethereal does that, but it does so by trying to read
                 * the first two packets of the file with each of the
                 * record header formats.  That currently means it seeks
                 * backwards and retries the reads, which doesn't work
                 * on pipes.  We want to be able to read from a pipe, so
                 * that strategy won't work; we'd have to buffer some
                 * data ourselves and read from that buffer in order to
                 * make that work.
                 */
                p->sf.hdrsize = sizeof(struct pcap_sf_patched_pkthdr);

                if (p->linktype == DLT_EN10MB) {
                        /*
                         * This capture might have been done in raw mode
                         * or cooked mode.
                         *
                         * If it was done in cooked mode, p->snapshot was
                         * passed to recvfrom() as the buffer size, meaning
                         * that the most packet data that would be copied
                         * would be p->snapshot.  However, a faked Ethernet
                         * header would then have been added to it, so the
                         * most data that would be in a packet in the file
                         * would be p->snapshot + 14.
                         *
                         * We can't easily tell whether the capture was done
                         * in raw mode or cooked mode, so we'll assume it was
                         * cooked mode, and add 14 to the snapshot length.
                         * That means that, for a raw capture, the snapshot
                         * length will be misleading if you use it to figure
                         * out why a capture doesn't have all the packet data,
                         * but there's not much we can do to avoid that.
                         */
                        p->snapshot += 14;
                }
        } else
                p->sf.hdrsize = sizeof(struct pcap_sf_pkthdr);

        /*
         * Allocate a buffer for the packet data.
         */
        p->bufsize = p->snapshot;
        if (p->bufsize <= 0) {
                /*
                 * Bogus snapshot length; use 64KiB as a fallback.
                 */
                p->bufsize = 65536;
        }
        p->buffer = malloc(p->bufsize);
        if (p->buffer == NULL) {
                snprintf(errbuf, PCAP_ERRBUF_SIZE, "out of memory");
                return (-1);
        }

        return (1);
}

/*
 * Read and return the next packet from the savefile.  Return the header
 * in hdr and a pointer to the contents in data.  Return 0 on success, 1
 * if there were no more packets, and -1 on an error.
 */
static int
pcap_next_packet(pcap_t *p, struct pcap_pkthdr *hdr, u_char **data)
{
        struct pcap_sf_patched_pkthdr sf_hdr;
        FILE *fp = p->sf.rfile;
        size_t amt_read;
        bpf_u_int32 t;

        /*
         * Read the packet header; the structure we use as a buffer
         * is the longer structure for files generated by the patched
         * libpcap, but if the file has the magic number for an
         * unpatched libpcap we only read as many bytes as the regular
         * header has.
         */
        amt_read = fread(&sf_hdr, 1, p->sf.hdrsize, fp);
        if (amt_read != p->sf.hdrsize) {
                if (ferror(fp)) {
                        snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
                            "error reading dump file: %s",
                            pcap_strerror(errno));
                        return (-1);
                } else {
                        if (amt_read != 0) {
                                snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
                                    "truncated dump file; tried to read %lu header bytes, only got %lu",
                                    (unsigned long)p->sf.hdrsize,
                                    (unsigned long)amt_read);
                                return (-1);
                        }
                        /* EOF */
                        return (1);
                }
        }

        if (p->sf.swapped) {
                /* these were written in opposite byte order */
                hdr->caplen = SWAPLONG(sf_hdr.caplen);
                hdr->len = SWAPLONG(sf_hdr.len);
                hdr->ts.tv_sec = SWAPLONG(sf_hdr.ts.tv_sec);
                hdr->ts.tv_usec = SWAPLONG(sf_hdr.ts.tv_usec);
        } else {
                hdr->caplen = sf_hdr.caplen;
                hdr->len = sf_hdr.len;
                hdr->ts.tv_sec = sf_hdr.ts.tv_sec;
                hdr->ts.tv_usec = sf_hdr.ts.tv_usec;
        }
        /* Swap the caplen and len fields, if necessary. */
        switch (p->sf.lengths_swapped) {

        case NOT_SWAPPED:
                break;

        case MAYBE_SWAPPED:
                if (hdr->caplen <= hdr->len) {
                        /*
                         * The captured length is <= the actual length,
                         * so presumably they weren't swapped.
                         */
                        break;
                }
                /* FALLTHROUGH */

        case SWAPPED:
                t = hdr->caplen;
                hdr->caplen = hdr->len;
                hdr->len = t;
                break;
        }

        if (hdr->caplen > p->bufsize) {
                /*
                 * This can happen due to Solaris 2.3 systems tripping
                 * over the BUFMOD problem and not setting the snapshot
                 * correctly in the savefile header.  If the caplen isn't
                 * grossly wrong, try to salvage.
                 */
                static u_char *tp = NULL;
                static size_t tsize = 0;

                if (hdr->caplen > 65535) {
                        snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
                            "bogus savefile header");
                        return (-1);
                }

                if (tsize < hdr->caplen) {
                        tsize = ((hdr->caplen + 1023) / 1024) * 1024;
                        if (tp != NULL)
                                free((u_char *)tp);
                        tp = (u_char *)malloc(tsize);
                        if (tp == NULL) {
                                tsize = 0;
                                snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
                                    "BUFMOD hack malloc");
                                return (-1);
                        }
                }
                amt_read = fread((char *)tp, 1, hdr->caplen, fp);
                if (amt_read != hdr->caplen) {
                        if (ferror(fp)) {
                                snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
                                    "error reading dump file: %s",
                                    pcap_strerror(errno));
                        } else {
                                snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
                                    "truncated dump file; tried to read %u captured bytes, only got %lu",
                                    hdr->caplen, (unsigned long)amt_read);
                        }
                        return (-1);
                }
                /*
                 * We can only keep up to p->bufsize bytes.  Since
                 * caplen > p->bufsize is exactly how we got here,
                 * we know we can only keep the first p->bufsize bytes
                 * and must drop the remainder.  Adjust caplen accordingly,
                 * so we don't get confused later as to how many bytes we
                 * have to play with.
                 */
                hdr->caplen = p->bufsize;
                memcpy(p->buffer, (char *)tp, p->bufsize);
        } else {
                /* read the packet itself */
                amt_read = fread(p->buffer, 1, hdr->caplen, fp);
                if (amt_read != hdr->caplen) {
                        if (ferror(fp)) {
                                snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
                                    "error reading dump file: %s",
                                    pcap_strerror(errno));
                        } else {
                                snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
                                    "truncated dump file; tried to read %u captured bytes, only got %lu",
                                    hdr->caplen, (unsigned long)amt_read);
                        }
                        return (-1);
                }
        }
        *data = p->buffer;

        if (p->sf.swapped) {
                /*
                 * Convert pseudo-headers from the byte order of
                 * the host on which the file was saved to our
                 * byte order, as necessary.
                 */
                switch (p->linktype) {

                case DLT_USB_LINUX:
                        swap_linux_usb_header(hdr, *data, 0);
                        break;

                case DLT_USB_LINUX_MMAPPED:
                        swap_linux_usb_header(hdr, *data, 1);
                        break;
                }
        }

        return (0);
}

static int
sf_write_header(FILE *fp, int linktype, int thiszone, int snaplen)
{
        struct pcap_file_header hdr;

        hdr.magic = TCPDUMP_MAGIC;
        hdr.version_major = PCAP_VERSION_MAJOR;
        hdr.version_minor = PCAP_VERSION_MINOR;

        hdr.thiszone = thiszone;
        hdr.snaplen = snaplen;
        hdr.sigfigs = 0;
        hdr.linktype = linktype;

        if (fwrite((char *)&hdr, sizeof(hdr), 1, fp) != 1)
                return (-1);

        return (0);
}

/*
 * Output a packet to the initialized dump file.
 */
void
pcap_dump(u_char *user, const struct pcap_pkthdr *h, const u_char *sp)
{
        register FILE *f;
        struct pcap_sf_pkthdr sf_hdr;

        f = (FILE *)user;
        sf_hdr.ts.tv_sec  = h->ts.tv_sec;
        sf_hdr.ts.tv_usec = h->ts.tv_usec;
        sf_hdr.caplen     = h->caplen;
        sf_hdr.len        = h->len;
        /* XXX we should check the return status */
        (void)fwrite(&sf_hdr, sizeof(sf_hdr), 1, f);
        (void)fwrite(sp, h->caplen, 1, f);
}

static pcap_dumper_t *
pcap_setup_dump(pcap_t *p, int linktype, FILE *f, const char *fname)
{

#if defined(WIN32) || defined(MSDOS)
        /*
         * If we're writing to the standard output, put it in binary
         * mode, as savefiles are binary files.
         *
         * Otherwise, we turn off buffering.
         * XXX - why?  And why not on the standard output?
         */
        if (f == stdout)
                SET_BINMODE(f);
        else
                setbuf(f, NULL);
#endif
        if (sf_write_header(f, linktype, p->tzoff, p->snapshot) == -1) {
                snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "Can't write to %s: %s",
                    fname, pcap_strerror(errno));
                if (f != stdout)
                        (void)fclose(f);
                return (NULL);
        }
        return ((pcap_dumper_t *)f);
}

/*
 * Initialize so that sf_write() will output to the file named 'fname'.
 */
pcap_dumper_t *
pcap_dump_open(pcap_t *p, const char *fname)
{
        FILE *f;
        int linktype;

        /*
         * If this pcap_t hasn't been activated, it doesn't have a
         * link-layer type, so we can't use it.
         */
        if (!p->activated) {
                snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
                    "%s: not-yet-activated pcap_t passed to pcap_dump_open",
                    fname);
                return (NULL);
        }
        linktype = dlt_to_linktype(p->linktype);
        if (linktype == -1) {
                snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
                    "%s: link-layer type %d isn't supported in savefiles",
                    fname, p->linktype);
                return (NULL);
        }
        linktype |= p->linktype_ext;

        if (fname[0] == '-' && fname[1] == '\0') {
                f = stdout;
                fname = "standard output";
        } else {
#if !defined(WIN32) && !defined(MSDOS)
                f = fopen(fname, "w");
#else
                f = fopen(fname, "wb");
#endif
                if (f == NULL) {
                        snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "%s: %s",
                            fname, pcap_strerror(errno));
                        return (NULL);
                }
        }
        return (pcap_setup_dump(p, linktype, f, fname));
}

/*
 * Initialize so that sf_write() will output to the given stream.
 */
pcap_dumper_t *
pcap_dump_fopen(pcap_t *p, FILE *f)
{       
        int linktype;

        linktype = dlt_to_linktype(p->linktype);
        if (linktype == -1) {
                snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
                    "stream: link-layer type %d isn't supported in savefiles",
                    p->linktype);
                return (NULL);
        }
        linktype |= p->linktype_ext;

        return (pcap_setup_dump(p, linktype, f, "stream"));
}

FILE *
pcap_dump_file(pcap_dumper_t *p)
{
        return ((FILE *)p);
}

long
pcap_dump_ftell(pcap_dumper_t *p)
{
        return (ftell((FILE *)p));
}

int
pcap_dump_flush(pcap_dumper_t *p)
{

        if (fflush((FILE *)p) == EOF)
                return (-1);
        else
                return (0);
}

void
pcap_dump_close(pcap_dumper_t *p)
{

#ifdef notyet
        if (ferror((FILE *)p))
                return-an-error;
        /* XXX should check return from fclose() too */
#endif
        (void)fclose((FILE *)p);
}