request.c

igmp proxy 实现源码

/*
**  igmpproxy - IGMP proxy based multicast router 
**  Copyright (C) 2005 Johnny Egeland <[e-mail]>
**
**  This program is free software; you can redistribute it and/or modify
**  it under the terms of the GNU General Public License as published by
**  the Free Software Foundation; either version 2 of the License, or
**  (at your option) any later version.
**
**  This program is distributed in the hope that it will be useful,
**  but WITHOUT ANY WARRANTY; without even the implied warranty of
**  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
**  GNU General Public License for more details.
**
**  You should have received a copy of the GNU General Public License
**  along with this program; if not, write to the Free Software
**  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
**
**----------------------------------------------------------------------------
**
**  This software is derived work from the following software. The original
**  source code has been modified from it's original state by the author
**  of igmpproxy.
**
**  smcroute 0.92 - Copyright (C) 2001 Carsten Schill <[e-mail]>
**  - Licensed under the GNU General Public License, version 2
**  
**  mrouted 3.9-beta3 - COPYRIGHT 1989 by The Board of Trustees of 
**  Leland Stanford Junior University.
**  - Original license can be found in the "doc/mrouted-LINCESE" file.
**
*/
/**
*   request.c 
*
*   Functions for recieveing and processing IGMP requests.
*
*/

#include "defs.h"

// Prototypes...
void sendGroupSpecificMemberQuery(void *argument);  
    
typedef struct {
    uint32      group;
    uint32      vifAddr;
    short       started;
} GroupVifDesc;


/**
*   Handles incoming membership reports, and
*   appends them to the routing table.
*/
void acceptGroupReport(uint32 src, uint32 group, uint8 type) {
    struct IfDesc  *sourceVif;

    // Sanitycheck the group adress...
    if(!IN_MULTICAST( ntohl(group) )) {
        log(LOG_WARNING, 0, "The group address %s is not a valid Multicast group.",
            inetFmt(group, s1));
        return;
    }

    // Find the interface on which the report was recieved.
    sourceVif = getIfByAddress( src );
    if(sourceVif == NULL) {
        log(LOG_WARNING, 0, "No interfaces found for source %s",
            inetFmt(src,s1));
        return;
    }

    if(sourceVif->InAdr.s_addr == src) {
        log(LOG_NOTICE, 0, "The IGMP message was from myself. Ignoring.");
        return;
    }

    // We have a IF so check that it's an downstream IF.
    if(sourceVif->state == IF_STATE_DOWNSTREAM) {

        IF_DEBUG log(LOG_DEBUG, 0, "Should insert group %s (from: %s) to route table. Vif Ix : %d",
            inetFmt(group,s1), inetFmt(src,s2), sourceVif->index);

        // The membership report was OK... Insert it into the route table..
        insertRoute(group, sourceVif->index);


    } else {
        // Log the state of the interface the report was recieved on.
        log(LOG_INFO, 0, "Mebership report was recieved on %s. Ignoring.",
            sourceVif->state==IF_STATE_UPSTREAM?"the upstream interface":"a disabled interface");
    }

}

/**
*   Recieves and handles a group leave message.
*/
void acceptLeaveMessage(uint32 src, uint32 group) {
    struct IfDesc   *sourceVif;
    
    IF_DEBUG log(LOG_DEBUG, 0, "Got leave message from %s to %s. Starting last member detection.",
                 inetFmt(src, s1), inetFmt(group, s2));

    // Sanitycheck the group adress...
    if(!IN_MULTICAST( ntohl(group) )) {
        log(LOG_WARNING, 0, "The group address %s is not a valid Multicast group.",
            inetFmt(group, s1));
        return;
    }

    // Find the interface on which the report was recieved.
    sourceVif = getIfByAddress( src );
    if(sourceVif == NULL) {
        log(LOG_WARNING, 0, "No interfaces found for source %s",
            inetFmt(src,s1));
        return;
    }

    // We have a IF so check that it's an downstream IF.
    if(sourceVif->state == IF_STATE_DOWNSTREAM) {

        GroupVifDesc   *gvDesc;
        gvDesc = (GroupVifDesc*) malloc(sizeof(GroupVifDesc));

        // Tell the route table that we are checking for remaining members...
        setRouteLastMemberMode(group);

        // Call the group spesific membership querier...
        gvDesc->group = group;
        gvDesc->vifAddr = sourceVif->InAdr.s_addr;
        gvDesc->started = 0;

        sendGroupSpecificMemberQuery(gvDesc);

    } else {
        // just ignore the leave request...
        IF_DEBUG log(LOG_DEBUG, 0, "The found if for %s was not downstream. Ignoring leave request.");
    }
}

/**
*   Sends a group specific member report query until the 
*   group times out...
*/
void sendGroupSpecificMemberQuery(void *argument) {
    struct  Config  *conf = getCommonConfig();

    // Cast argument to correct type...
    GroupVifDesc   *gvDesc = (GroupVifDesc*) argument;

    if(gvDesc->started) {
        // If aging returns false, we don't do any further action...
        if(!lastMemberGroupAge(gvDesc->group)) {
            return;
        }
    } else {
        gvDesc->started = 1;
    }

    // Send a group specific membership query...
    sendIgmp(gvDesc->vifAddr, gvDesc->group, 
             IGMP_MEMBERSHIP_QUERY,
             conf->lastMemberQueryInterval * IGMP_TIMER_SCALE, 
             gvDesc->group, 0);

    IF_DEBUG log(LOG_DEBUG, 0, "Sent membership query from %s to %s. Delay: %d",
        inetFmt(gvDesc->vifAddr,s1), inetFmt(gvDesc->group,s2),
        conf->lastMemberQueryInterval);

    // Set timeout for next round...
    timer_setTimer(conf->lastMemberQueryInterval, sendGroupSpecificMemberQuery, gvDesc);

}


/**
*   Sends a general membership query on downstream VIFs
*/
void sendGeneralMembershipQuery() {
    struct  Config  *conf = getCommonConfig();
    struct  IfDesc  *Dp;
    int             Ix;

    // Loop through all downstream vifs...
    for ( Ix = 0; Dp = getIfByIx( Ix ); Ix++ ) {
        if ( Dp->InAdr.s_addr && ! (Dp->Flags & IFF_LOOPBACK) ) {
            if(Dp->state == IF_STATE_DOWNSTREAM) {
                // Send the membership query...
                sendIgmp(Dp->InAdr.s_addr, allhosts_group, 
                         IGMP_MEMBERSHIP_QUERY,
                         conf->queryResponseInterval * IGMP_TIMER_SCALE, 0, 0);
                
                IF_DEBUG log(LOG_DEBUG, 0, "Sent membership query from %s to %s. Delay: %d",
                    inetFmt(Dp->InAdr.s_addr,s1), inetFmt(allhosts_group,s2),
                    conf->queryResponseInterval);
            }
        }
    }

    // Install timer for aging active routes.
    timer_setTimer(conf->queryResponseInterval, ageActiveRoutes, NULL);

    // Install timer for next general query...
    if(conf->startupQueryCount>0) {
        // Use quick timer...
        timer_setTimer(conf->startupQueryInterval, sendGeneralMembershipQuery, NULL);
        // Decrease startup counter...
        conf->startupQueryCount--;
    } 
    else {
        // Use slow timer...
        timer_setTimer(conf->queryInterval, sendGeneralMembershipQuery, NULL);
    }


}