extend.c

开发snmp的开发包有两个开放的SNMP开发库

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

#include "agent/extend.h"
#include "utilities/execute.h"
#include "struct.h"

#ifndef USING_UCD_SNMP_EXTENSIBLE_MODULE
#include "util_funcs.h"
#include "mibdefs.h"
#define SHELLCOMMAND 3
#endif

oid  ns_extend_oid[]    = { 1, 3, 6, 1, 4, 1, 8072, 1, 3, 2 };
oid  extend_count_oid[] = { 1, 3, 6, 1, 4, 1, 8072, 1, 3, 2, 1 };
oid  extend_config_oid[] = { 1, 3, 6, 1, 4, 1, 8072, 1, 3, 2, 2 };
oid  extend_out1_oid[]  = { 1, 3, 6, 1, 4, 1, 8072, 1, 3, 2, 3 };
oid  extend_out2_oid[]  = { 1, 3, 6, 1, 4, 1, 8072, 1, 3, 2, 4 };

typedef struct extend_registration_block_s {
    netsnmp_table_data *dinfo;
    oid                *root_oid;
    size_t              oid_len;
    long                num_entries;
    netsnmp_extend     *ehead;
    netsnmp_handler_registration       *reg[3];
    struct extend_registration_block_s *next;
} extend_registration_block;
extend_registration_block *ereg_head = NULL;


#ifndef USING_UCD_SNMP_EXTENSIBLE_MODULE
typedef struct netsnmp_old_extend_s {
    int idx;
    netsnmp_extend *exec_entry;
    netsnmp_extend *efix_entry;
} netsnmp_old_extend;

int             num_compatability_entries = 0;
int             max_compatability_entries = 50;
netsnmp_old_extend *compatability_entries;

WriteMethod fixExec2Error;
FindVarMethod var_extensible_old;
oid  old_extensible_variables_oid[] = { NETSNMP_UCDAVIS_MIB, NETSNMP_SHELLMIBNUM, 1 };
struct variable2 old_extensible_variables[] = {
    {MIBINDEX,     ASN_INTEGER,   RONLY, var_extensible_old, 1, {MIBINDEX}},
    {ERRORNAME,    ASN_OCTET_STR, RONLY, var_extensible_old, 1, {ERRORNAME}},
    {SHELLCOMMAND, ASN_OCTET_STR, RONLY, var_extensible_old, 1, {SHELLCOMMAND}},
    {ERRORFLAG,    ASN_INTEGER,   RONLY, var_extensible_old, 1, {ERRORFLAG}},
    {ERRORMSG,     ASN_OCTET_STR, RONLY, var_extensible_old, 1, {ERRORMSG}},
    {ERRORFIX,     ASN_INTEGER,  RWRITE, var_extensible_old, 1, {ERRORFIX}},
    {ERRORFIXCMD,  ASN_OCTET_STR, RONLY, var_extensible_old, 1, {ERRORFIXCMD}}
};
#endif


        /*************************
         *
         *  Main initialisation routine
         *
         *************************/

extend_registration_block *
_find_extension_block( oid *name, size_t name_len )
{
    extend_registration_block         *eptr;
    size_t len;
    for ( eptr=ereg_head; eptr; eptr=eptr->next ) {
        len = SNMP_MIN(name_len, eptr->oid_len);
        if (!snmp_oid_compare( name, len, eptr->root_oid, eptr->oid_len))
            return eptr;
    }
    return NULL;
}

extend_registration_block *
_register_extend( oid *base, size_t len )
{
    extend_registration_block         *eptr;
    oid oid_buf[MAX_OID_LEN];

    netsnmp_table_data                *dinfo;
    netsnmp_table_registration_info   *tinfo;
    netsnmp_watcher_info              *winfo;
    netsnmp_handler_registration      *reg;

    for ( eptr=ereg_head; eptr; eptr=eptr->next ) {
        if (!snmp_oid_compare( base, len, eptr->root_oid, eptr->oid_len))
            return eptr;
    }
    if (!eptr) {
        eptr = SNMP_MALLOC_TYPEDEF( extend_registration_block );
        eptr->root_oid = snmp_duplicate_objid( base, len );
        eptr->oid_len  = len;
        eptr->num_entries = 0;
        eptr->ehead       = NULL;
        eptr->dinfo       = netsnmp_create_table_data( "nsExtendTable" );
        eptr->next        = ereg_head;
        ereg_head         = eptr;
    }

    dinfo = eptr->dinfo;
    memcpy( oid_buf, base, len*sizeof(oid) );

        /*
         * Register the configuration table
         */
    tinfo = SNMP_MALLOC_TYPEDEF( netsnmp_table_registration_info );
    netsnmp_table_helper_add_indexes( tinfo, ASN_OCTET_STR, 0 );
    tinfo->min_column = COLUMN_EXTCFG_FIRST_COLUMN;
    tinfo->max_column = COLUMN_EXTCFG_LAST_COLUMN;
    oid_buf[len] = 2;
    reg   = netsnmp_create_handler_registration(
                "nsExtendConfigTable", handle_nsExtendConfigTable, 
                oid_buf, len+1, HANDLER_CAN_RWRITE);
    netsnmp_register_table_data( reg, dinfo, tinfo );
    eptr->reg[0] = reg;

        /*
         * Register the main output table
         *   using the same table_data handle.
         * This is sufficient to link the two tables,
         *   and implement the AUGMENTS behaviour
         */
    tinfo = SNMP_MALLOC_TYPEDEF( netsnmp_table_registration_info );
    netsnmp_table_helper_add_indexes( tinfo, ASN_OCTET_STR, 0 );
    tinfo->min_column = COLUMN_EXTOUT1_FIRST_COLUMN;
    tinfo->max_column = COLUMN_EXTOUT1_LAST_COLUMN;
    oid_buf[len] = 3;
    reg   = netsnmp_create_handler_registration(
                "nsExtendOut1Table", handle_nsExtendOutput1Table, 
                oid_buf, len+1, HANDLER_CAN_RONLY);
    netsnmp_register_table_data( reg, dinfo, tinfo );
    eptr->reg[1] = reg;

        /*
         * Register the multi-line output table
         *   using a simple table helper.
         * This handles extracting the indexes from
         *   the request OID, but leaves most of
         *   the work to our handler routine.
         * Still, it was nice while it lasted...
         */
    tinfo = SNMP_MALLOC_TYPEDEF( netsnmp_table_registration_info );
    netsnmp_table_helper_add_indexes( tinfo, ASN_OCTET_STR, ASN_INTEGER, 0 );
    tinfo->min_column = COLUMN_EXTOUT2_FIRST_COLUMN;
    tinfo->max_column = COLUMN_EXTOUT2_LAST_COLUMN;
    oid_buf[len] = 4;
    reg   = netsnmp_create_handler_registration(
                "nsExtendOut2Table", handle_nsExtendOutput2Table, 
                oid_buf, len+1, HANDLER_CAN_RONLY);
    netsnmp_register_table( reg, tinfo );
    eptr->reg[2] = reg;

        /*
         * Register a watched scalar to keep track of the number of entries
         */
    oid_buf[len] = 1;
    reg   = netsnmp_create_handler_registration(
                "nsExtendNumEntries", NULL, 
                oid_buf, len+1, HANDLER_CAN_RONLY);
    winfo = netsnmp_create_watcher_info(
                &(eptr->num_entries), sizeof(eptr->num_entries),
                ASN_INTEGER, WATCHER_FIXED_SIZE);
    netsnmp_register_watched_scalar( reg, winfo );

    return eptr;
}

int
extend_clear_callback(int majorID, int minorID,
                    void *serverarg, void *clientarg)
{
    extend_registration_block *eptr, *enext = NULL;

    for ( eptr=ereg_head; eptr; eptr=enext ) {
        enext=eptr->next;
        netsnmp_unregister_handler( eptr->reg[0] );
        netsnmp_unregister_handler( eptr->reg[1] );
        netsnmp_unregister_handler( eptr->reg[2] );
        SNMP_FREE(eptr);
    }
    ereg_head = NULL;
    return 0;
}

void init_extend( void )
{
    snmpd_register_config_handler("extend",    extend_parse_config, NULL, NULL);
    snmpd_register_config_handler("extend-sh", extend_parse_config, NULL, NULL);
    snmpd_register_config_handler("extendfix", extend_parse_config, NULL, NULL);
    snmpd_register_config_handler("exec2", extend_parse_config, NULL, NULL);
    snmpd_register_config_handler("sh2",   extend_parse_config, NULL, NULL);
    snmpd_register_config_handler("execFix2", extend_parse_config, NULL, NULL);
    (void)_register_extend( ns_extend_oid, OID_LENGTH(ns_extend_oid));

#ifndef USING_UCD_SNMP_EXTENSIBLE_MODULE
    snmpd_register_config_handler("exec", extend_parse_config, NULL, NULL);
    snmpd_register_config_handler("sh",   extend_parse_config, NULL, NULL);
    snmpd_register_config_handler("execFix", extend_parse_config, NULL, NULL);
    compatability_entries = calloc( max_compatability_entries,
                                    sizeof(netsnmp_old_extend));
    REGISTER_MIB("ucd-extensible", old_extensible_variables,
                 variable2, old_extensible_variables_oid);
#endif

    snmp_register_callback(SNMP_CALLBACK_APPLICATION,
                           SNMPD_CALLBACK_PRE_UPDATE_CONFIG,
                           extend_clear_callback, NULL);
}

        /*************************
         *
         *  Cached-data hooks
         *  see 'cache_handler' helper
         *
         *************************/

int
extend_load_cache(netsnmp_cache *cache, void *magic)
{
    int  out_len = 1024*100;
    char out_buf[ 1024*100 ];
    int  cmd_len = 255*2 + 2;	/* 2 * DisplayStrings */
    char cmd_buf[ 255*2 + 2 ];
    int  ret;
    char *cp;
    char *line_buf[ 1024 ];
    netsnmp_extend *extension = (netsnmp_extend *)magic;

    if (!magic)
        return -1;
    DEBUGMSGTL(( "nsExtendTable:cache", "load %s", extension->token ));
    if ( extension->args )
        snprintf( cmd_buf, cmd_len, "%s %s", extension->command, extension->args );
    else 
        snprintf( cmd_buf, cmd_len, "%s", extension->command );
    if ( extension->flags & NS_EXTEND_FLAGS_SHELL )
        ret = run_shell_command( cmd_buf, extension->input, out_buf, &out_len);
    else
        ret = run_exec_command(  cmd_buf, extension->input, out_buf, &out_len);
    DEBUGMSG(( "nsExtendTable:cache", ": %s : %d\n", cmd_buf, ret));
    if (ret >= 0) {
        if (out_buf[   out_len-1 ] == '\n')
            out_buf[ --out_len   ] =  '\0';	/* Stomp on trailing newline */
        extension->output   = strdup( out_buf );
        extension->out_len  = out_len;
        /*
         * Now we need to pick the output apart into separate lines.
         * Start by counting how many lines we've got, and keeping
         * track of where each line starts in a static buffer
         */
        extension->numlines = 1;
        line_buf[ 0 ] = extension->output;
        for (cp=extension->output; *cp; cp++) {
            if (*cp == '\n') {
                line_buf[ extension->numlines++ ] = cp+1;
            }
        }
        if ( extension->numlines > 1 ) {
            extension->lines = calloc( sizeof(char *), extension->numlines );
            memcpy( extension->lines, line_buf,
                                       sizeof(char *) * extension->numlines );
        } else {
            extension->lines = &extension->output;
        }
    }
    extension->result = ret;
    return ret;
}

void
extend_free_cache(netsnmp_cache *cache, void *magic)
{
    netsnmp_extend *extension = (netsnmp_extend *)magic;
    if (!magic)
        return;

    DEBUGMSGTL(( "nsExtendTable:cache", "free %s\n", extension->token ));
    if (extension->output) {
        SNMP_FREE(extension->output);
        extension->output = NULL;
    }
    if ( extension->numlines > 1 ) {
        SNMP_FREE(extension->lines);
    }
    extension->lines  = NULL;
    extension->out_len  = 0;
    extension->numlines = 0;
}


        /*************************
         *
         *  Utility routines for setting up a new entry
         *  (either via SET requests, or the config file)
         *
         *************************/

void
_free_extension( netsnmp_extend *extension, extend_registration_block *ereg )
{
    netsnmp_extend *eptr  = NULL;
    netsnmp_extend *eprev = NULL;

    if (!extension)
        return;

    if (ereg) {
        /* Unlink from 'ehead' list */
        for (eptr=ereg->ehead; eptr; eptr=eptr->next) {
            if (eptr == extension)
                break;
            eprev = eptr;
        }
        if (!eptr) {
            snmp_log(LOG_ERR,
                     "extend: fell off end of list before finding extension\n");
            return;
        }
        if (eprev)
            eprev->next = eptr->next;
        else
            ereg->ehead = eptr->next;
    }

    netsnmp_table_data_remove_and_delete_row( ereg->dinfo, extension->row);
    SNMP_FREE( extension->token );
    SNMP_FREE( extension->cache );
    SNMP_FREE( extension->command );
    SNMP_FREE( extension->args  );
    SNMP_FREE( extension->input );
    SNMP_FREE( extension );
    return;
}

netsnmp_extend *
_new_extension( char *exec_name, int exec_flags, extend_registration_block *ereg )
{
    netsnmp_extend     *extension;
    netsnmp_table_row  *row;
    netsnmp_extend     *eptr1, *eptr2; 
    netsnmp_table_data *dinfo = ereg->dinfo;

    if (!exec_name)
        return NULL;
    extension = SNMP_MALLOC_TYPEDEF( netsnmp_extend );
    if (!extension)
        return NULL;
    extension->token    = strdup( exec_name );
    extension->flags    = exec_flags;
    extension->cache    = netsnmp_cache_create( 0, extend_load_cache,