interface_linux.c

snmp的源代码,已经在我的ubuntu下编译通过

/*
 *  Interface MIB architecture support
 *
 * $Id: interface_linux.c,v 1.20 2004/10/18 03:49:50 rstory Exp $
 */
#include <net-snmp/net-snmp-config.h>
#include <net-snmp/net-snmp-includes.h>
#include "mibII/mibII_common.h"
#include "if-mib/ifTable/ifTable_constants.h"

#include <net-snmp/agent/net-snmp-agent-includes.h>

#if HAVE_SYS_IOCTL_H
#include <sys/ioctl.h>
#else
#error "linux should have sys/ioctl header"
#endif

#include <net-snmp/data_access/interface.h>
#include "if-mib/data_access/interface.h"
#include "interface_ioctl.h"

unsigned int
netsnmp_arch_interface_get_if_speed(int fd, const char *name);

void
netsnmp_arch_interface_init(void)
{
    /*
     * nothing to do
     */
}

/*
 * find the ifIndex for an interface name
 * NOTE: The Linux version is not efficient for large numbers of calls.
 *   consider using netsnmp_access_interface_ioctl_ifindex_get()
 *   for loops which need to look up a lot of indexes.
 *
 * @retval 0 : no index found
 * @retval >0: ifIndex for interface
 */
oid
netsnmp_arch_interface_index_find(const char *name)
{
    return netsnmp_access_interface_ioctl_ifindex_get(-1, name);
}


/*
 *
 * @retval  0 success
 * @retval -1 no container specified
 * @retval -2 could not open /proc/net/dev
 * @retval -3 could not create entry (probably malloc)
 */
int
netsnmp_arch_interface_container_load(netsnmp_container* container,
                                      u_int load_flags)
{
    FILE           *devin;
    char            line[256];
    /*
     * scanline_2_2:
     *  [               IN                        ]
     *   byte pkts errs drop fifo frame cmprs mcst |
     *  [               OUT                               ]
     *   byte pkts errs drop fifo colls carrier compressed
     */
#ifdef SCNuMAX
    uintmax_t       rec_pkt, rec_oct, rec_err, rec_drop, rec_mcast;
    uintmax_t       snd_pkt, snd_oct, snd_err, snd_drop, coll;
    const char     *scan_line_2_2 =
        "%"   SCNuMAX " %"  SCNuMAX " %"  SCNuMAX " %"  SCNuMAX
        " %*" SCNuMAX " %*" SCNuMAX " %*" SCNuMAX " %"  SCNuMAX
        " %"  SCNuMAX " %"  SCNuMAX " %"  SCNuMAX " %"  SCNuMAX
        " %*" SCNuMAX " %"  SCNuMAX;
    const char     *scan_line_2_0 =
        "%"   SCNuMAX " %"  SCNuMAX " %*" SCNuMAX " %*" SCNuMAX
        " %*" SCNuMAX " %"  SCNuMAX " %"  SCNuMAX " %*" SCNuMAX
        " %*" SCNuMAX " %"  SCNuMAX;
#else
    unsigned long   rec_pkt, rec_oct, rec_err, rec_drop, rec_mcast;
    unsigned long   snd_pkt, snd_oct, snd_err, snd_drop, coll;
    const char     *scan_line_2_2 =
        "%lu %lu %lu %lu %*lu %*lu %*lu %lu %lu %lu %lu %lu %*lu %lu";
    const char     *scan_line_2_0 =
        "%lu %lu %*lu %*lu %*lu %lu %lu %*lu %*lu %lu";
#endif
    static const char     *scan_line_to_use = NULL;
    static char     scan_expected;
    int             scan_count, fd;
    netsnmp_interface_entry *entry = NULL;
    struct ifreq ifrq;

    DEBUGMSGTL(("access:interface:container:arch", "load (flags %p)\n",
                load_flags));

    if (NULL == container) {
        snmp_log(LOG_ERR, "no container specified/found for interface\n");
        return -1;
    }

    if (!(devin = fopen("/proc/net/dev", "r"))) {
        DEBUGMSGTL(("access:interface",
                    "Failed to load Interface Table (linux1)\n"));
        snmp_log(LOG_ERR, "cannot open /proc/net/dev ...\n");
        return -2;
    }

    /*
     * create socket for ioctls
     */
    fd = socket(AF_INET, SOCK_DGRAM, 0);
    if(fd < 0) {
        snmp_log(LOG_ERR, "could not create socket\n");
        return -2;
    }

    /*
     * Read the first two lines of the file, containing the header
     * This indicates which version of the kernel we're working with,
     * and hence which statistics are actually available.
     *
     * Wes originally suggested parsing the field names in this header
     * to detect the position of individual fields directly,
     * but I suspect this is probably more trouble than it's worth.
     */
    fgets(line, sizeof(line), devin);
    fgets(line, sizeof(line), devin);
    /*
     * XXX - What's the format for the 2.6 kernel ?
     */
    if( NULL == scan_line_to_use ) {
        if (strstr(line, "compressed")) {
            scan_line_to_use = scan_line_2_2;
            scan_expected = 10;
            DEBUGMSGTL(("access:interface",
                        "using linux 2.2 kernel /proc/net/dev\n"));
        } else {
            scan_line_to_use = scan_line_2_0;
            scan_expected = 5;
            DEBUGMSGTL(("access:interface",
                        "using linux 2.0 kernel /proc/net/dev\n"));
        }
    }

    /*
     * The rest of the file provides the statistics for each interface.
     * Read in each line in turn, isolate the interface name
     *   and retrieve (or create) the corresponding data structure.
     */
    while (fgets(line, sizeof(line), devin)) {
        char           *stats, *ifstart = line;

        if (line[strlen(line) - 1] == '\n')
            line[strlen(line) - 1] = '\0';

        while (*ifstart && *ifstart == ' ')
            ifstart++;

        if ((!*ifstart) || ((stats = strrchr(ifstart, ':')) == NULL)) {
            snmp_log(LOG_ERR,
                     "interface data format error 1, line ==|%s|\n", line);
            continue;
        }
        if ((scan_line_to_use == scan_line_2_2) && ((stats - line) < 6)) {
            snmp_log(LOG_ERR,
                     "interface data format error 2 (%d < 6), line ==|%s|\n",
                     line, stats - line);
        }

        DEBUGMSGTL(("9:access:ifcontainer", "processing '%s'\n", ifstart));

        /*
         * get index via ioctl.
         * If we've met this interface before, use the same index.
         * Otherwise find an unused index value and use that.
         */
        *stats++ = 0; /* null terminate name */
        entry = netsnmp_access_interface_entry_create(ifstart, 0);
        if(NULL == entry) {
            netsnmp_access_interface_container_free(container,
                                                    NETSNMP_ACCESS_INTERFACE_FREE_NOFLAGS);
            fclose(devin);
            close(fd);
            return -3;
        }

        /*
         * OK - we've now got (or created) the data structure for
         *      this interface, including any "static" information.
         * Now parse the rest of the line (i.e. starting from 'stats')
         *      to extract the relevant statistics, and populate
         *      data structure accordingly.
         * Use the ifentry flags field to indicate which counters are valid
         */
        while (*stats == ' ')
            stats++;

        rec_pkt = rec_oct = rec_err = rec_drop = rec_mcast = 0;
        snd_pkt = snd_oct = snd_err = snd_drop = coll = 0;
        if (scan_line_to_use == scan_line_2_2) {
            scan_count = sscanf(stats, scan_line_to_use,
                                &rec_oct, &rec_pkt, &rec_err, &rec_drop, &rec_mcast,
                                &snd_oct, &snd_pkt, &snd_err, &snd_drop,
                                &coll);
            if (scan_count == scan_expected) {
                entry->ns_flags |= NETSNMP_INTERFACE_FLAGS_HAS_BYTES;
                entry->ns_flags |= NETSNMP_INTERFACE_FLAGS_HAS_DROPS;
                /*
                 *  2.4 kernel includes a single multicast (input) counter?
                 */
                entry->ns_flags |= NETSNMP_INTERFACE_FLAGS_HAS_MCAST_PKTS;
                entry->ns_flags |= NETSNMP_INTERFACE_FLAGS_HAS_HIGH_SPEED;
#ifdef SCNuMAX   /* XXX - should be flag for 64-bit variables */
                entry->ns_flags |= NETSNMP_INTERFACE_FLAGS_HAS_HIGH_BYTES;
                entry->ns_flags |= NETSNMP_INTERFACE_FLAGS_HAS_HIGH_PACKETS;
#endif
            }
        } else {
            scan_count = sscanf(stats, scan_line_to_use,
                                &rec_pkt, &rec_err,
                                &snd_pkt, &snd_err, &coll);
            if (scan_count == scan_expected) {
                entry->ns_flags &= ~NETSNMP_INTERFACE_FLAGS_HAS_MCAST_PKTS;
                rec_oct = rec_drop = 0;
                snd_oct = snd_drop = 0;
            }
        }
        if(scan_count != scan_expected) {
            snmp_log(LOG_ERR,
                     "error scanning interface data (expected %d, got %d)\n",