route.c

snmp的源代码,已经在我的ubuntu下编译通过

struct iflist {
    int             index;
    char            name[64];
    struct iflist  *next;
}              *Iflist = NULL;

void
get_ifname(char *name, int ifIndex)
{
    netsnmp_pdu    *pdu, *response;
    netsnmp_variable_list *vp;
    struct iflist  *ip;
    oid             varname[MAX_OID_LEN];
    int             status;

    for (ip = Iflist; ip; ip = ip->next) {
        if (ip->index == ifIndex)
            break;
    }
    if (ip) {
        strcpy(name, ip->name);
        return;
    }
    ip = (struct iflist *) malloc(sizeof(struct iflist));
    if (ip == NULL)
        return;
    ip->next = Iflist;
    Iflist = ip;
    ip->index = ifIndex;
    pdu = snmp_pdu_create(SNMP_MSG_GET);
    memmove(varname, oid_ifdescr, sizeof(oid_ifdescr));
    varname[10] = (oid) ifIndex;
    snmp_add_null_var(pdu, varname, sizeof(oid_ifdescr) / sizeof(oid) + 1);
    status = snmp_synch_response(Session, pdu, &response);
    if (status == STAT_SUCCESS && response->errstat == SNMP_ERR_NOERROR) {
        vp = response->variables;
        if (vp->val_len >= sizeof(ip->name))
            vp->val_len = sizeof(ip->name) - 1;
        memmove(ip->name, vp->val.string, vp->val_len);
        ip->name[vp->val_len] = '\0';
        snmp_free_pdu(response);
    } else {
        sprintf(ip->name, "if%d", ifIndex);
    }
    strcpy(name, ip->name);
}

static          u_long
forgemask(u_long a)
{
    u_long          m;
    if (IN_CLASSA(a))
        m = IN_CLASSA_NET;
    else if (IN_CLASSB(a))
        m = IN_CLASSB_NET;
    else
        m = IN_CLASSC_NET;
    return m;
}

static void
domask(char *dst, u_long addr, u_long mask)
{
    int             b, i;
    if (!mask || forgemask(addr) == mask) {
        *dst = '\0';
        return;
    }
    i = 0;
    for (b = 0; b < 32; b++)
        if (mask & (1 << b)) {
            int             bb;
            i = b;
            for (bb = b + 1; bb < 32; bb++)
                if (!(mask & (1 << bb))) {
                    i = -1;     /* non-contig */
                    break;
                }
            break;
        }
    if (i == -1)
        sprintf(dst, "&0x%lx", mask);
    else
        sprintf(dst, "/%d", 32 - i);
}

char           *
routename(struct in_addr in)
{
    register char  *cp;
    static char     line[MAXHOSTNAMELEN + 1];
    struct hostent *hp;
    static char     domain[MAXHOSTNAMELEN + 1];
    static int      first = 1;

    if (first) {
        first = 0;
        if (gethostname(domain, MAXHOSTNAMELEN) == 0 &&
            (cp = (char *) strchr(domain, '.')))
            (void) strcpy(domain, cp + 1);
        else
            domain[0] = 0;
    }
    cp = 0;
    if (!nflag) {
        hp = gethostbyaddr((char *) &in, sizeof(struct in_addr), AF_INET);
        if (hp) {
            if ((cp = (char *) strchr(hp->h_name, '.')) &&
                !strcmp(cp + 1, domain))
                *cp = 0;
            cp = (char *) hp->h_name;
        }
    }
    if (cp)
        strncpy(line, cp, sizeof(line) - 1);
    else {
#define C(x)	(unsigned)((x) & 0xff)
        in.s_addr = ntohl(in.s_addr);
        sprintf(line, "%u.%u.%u.%u", C(in.s_addr >> 24),
                C(in.s_addr >> 16), C(in.s_addr >> 8), C(in.s_addr));
    }
    return (line);
}

/*
 * Return the name of the network whose address is given.
 * The address is assumed to be that of a net or subnet, not a host.
 */
char           *
netname(struct in_addr in, u_long mask)
{
    char           *cp = NULL;
    static char     line[MAXHOSTNAMELEN + 1];
    struct netent  *np = 0;
    u_long          net, omask;
    u_long          i;
    int             subnetshift;

    i = ntohl(in.s_addr);
    omask = mask = ntohl(mask);
    if (!nflag && i != INADDR_ANY) {
        if (mask == INADDR_ANY) {
            if (IN_CLASSA(i)) {
                mask = IN_CLASSA_NET;
                subnetshift = 8;
            } else if (IN_CLASSB(i)) {
                mask = IN_CLASSB_NET;
                subnetshift = 8;
            } else {
                mask = IN_CLASSC_NET;
                subnetshift = 4;
            }
            /*
             * If there are more bits than the standard mask
             * would suggest, subnets must be in use.
             * Guess at the subnet mask, assuming reasonable
             * width subnet fields.
             */
            while (i & ~mask)
                mask = (long) mask >> subnetshift;
        }
        net = i & mask;
        while ((mask & 1) == 0)
            mask >>= 1, net >>= 1;
        np = getnetbyaddr(net, AF_INET);
        if (np)
            cp = np->n_name;
    }
    if (cp)
        strncpy(line, cp, sizeof(line) - 1);
    else if ((i & 0xffffff) == 0)
        sprintf(line, "%u", C(i >> 24));
    else if ((i & 0xffff) == 0)
        sprintf(line, "%u.%u", C(i >> 24), C(i >> 16));
    else if ((i & 0xff) == 0)
        sprintf(line, "%u.%u.%u", C(i >> 24), C(i >> 16), C(i >> 8));
    else
        sprintf(line, "%u.%u.%u.%u", C(i >> 24),
                C(i >> 16), C(i >> 8), C(i));
    domask(line + strlen(line), i, omask);
    return (line);
}

/*
 * Print routing statistics
 */
void
rt_stats(void)
{
    netsnmp_variable_list *var;

    printf("routing:\n");
    var =
        getvarbyname(Session, oid_ipnoroutes,
                     sizeof(oid_ipnoroutes) / sizeof(oid));
    if (var) {
        printf("\t%lu destination%s found unreachable\n",
               *var->val.integer, plural((int) *var->val.integer));
        snmp_free_var(var);
    } else {
        printf("\tCouldn't get ipOutNoRoutes variable\n");
    }
}

/*
 * Request a variable with a GET REQUEST message on the given
 * session.  If the variable is found, a
 * pointer to a netsnmp_variable_list object will be returned.
 * Otherwise, NULL is returned.  The caller must free the returned
 * variable_list object when done with it.
 */
netsnmp_variable_list *
getvarbyname(netsnmp_session * sp, oid * name, size_t len)
{
    netsnmp_pdu    *request, *response;
    netsnmp_variable_list *var = NULL, *vp;
    int             status;

    request = snmp_pdu_create(SNMP_MSG_GET);

    snmp_add_null_var(request, name, len);

    status = snmp_synch_response(sp, request, &response);

    if (status == STAT_SUCCESS) {
        if (response->errstat == SNMP_ERR_NOERROR) {
            for (var = response->variables; var; var = var->next_variable) {
                if (var->name_length == len
                    && !memcmp(name, var->name, len * sizeof(oid)))
                    break;      /* found our match */
            }
            if (var != NULL) {
                /*
                 * Now unlink this var from pdu chain so it doesn't get freed.
                 * The caller will free the var.
                 */
                if (response->variables == var) {
                    response->variables = var->next_variable;
                } else {
                    for (vp = response->variables; vp;
                         vp = vp->next_variable) {
                        if (vp->next_variable == var) {
                            vp->next_variable = var->next_variable;
                            break;
                        }
                    }
                }
                if (var->type == SNMP_NOSUCHOBJECT ||
                    var->type == SNMP_NOSUCHINSTANCE ||
                    var->type == SNMP_ENDOFMIBVIEW) {
                       snmp_free_var(var);
                       var =  NULL;
                }
            }
        }
    } else if (status != STAT_TIMEOUT)
        snmp_sess_perror("snmpnetstat", sp);
    if (response)
        snmp_free_pdu(response);
    return var;
}