openvswitch/lib/sflow_receiver.c

/* Copyright (c) 2002-2009 InMon Corp. Licensed under the terms of either the
 *   Sun Industry Standards Source License 1.1, that is available at:
 *    http://host-sflow.sourceforge.net/sissl.html
 * or the InMon sFlow License, that is available at:
 *    http://www.inmon.com/technology/sflowlicense.txt
 */

#ifndef __CHECKER__            /* Don't run sparse on anything in this file. */

#include <assert.h>
#include "sflow_api.h"

static void resetSampleCollector(SFLReceiver *receiver);
static void sendSample(SFLReceiver *receiver);
static void sflError(SFLReceiver *receiver, char *errm);
inline static void putNet32(SFLReceiver *receiver, u_int32_t val);
inline static void putAddress(SFLReceiver *receiver, SFLAddress *addr);
#ifdef SFLOW_DO_SOCKET
static void initSocket(SFLReceiver *receiver);
#endif

/*_________________--------------------------__________________
  _________________    sfl_receiver_init     __________________
  -----------------__________________________------------------
*/

void sfl_receiver_init(SFLReceiver *receiver, SFLAgent *agent)
{
    /* first clear everything */
    memset(receiver, 0, sizeof(*receiver));

    /* now copy in the parameters */
    receiver->agent = agent;

    /* set defaults */
    receiver->sFlowRcvrMaximumDatagramSize = SFL_DEFAULT_DATAGRAM_SIZE;
    receiver->sFlowRcvrPort = SFL_DEFAULT_COLLECTOR_PORT;

#ifdef SFLOW_DO_SOCKET
    /* initialize the socket address */
    initSocket(receiver);
#endif

    /* preset some of the header fields */
    receiver->sampleCollector.datap = receiver->sampleCollector.data;
    putNet32(receiver, SFLDATAGRAM_VERSION5);
    putAddress(receiver, &agent->myIP);
    putNet32(receiver, agent->subId);

    /* prepare to receive the first sample */
    resetSampleCollector(receiver);
}

/*_________________---------------------------__________________
  _________________      reset                __________________
  -----------------___________________________------------------

  called on timeout, or when owner string is cleared
*/

static void reset(SFLReceiver *receiver) {
    // ask agent to tell samplers and pollers to stop sending samples
    sfl_agent_resetReceiver(receiver->agent, receiver);
    // reinitialize
    sfl_receiver_init(receiver, receiver->agent);
}

#ifdef SFLOW_DO_SOCKET
/*_________________---------------------------__________________
  _________________      initSocket           __________________
  -----------------___________________________------------------
*/

static void initSocket(SFLReceiver *receiver) {
    if(receiver->sFlowRcvrAddress.type == SFLADDRESSTYPE_IP_V6) {
	struct sockaddr_in6 *sa6 = &receiver->receiver6;
	sa6->sin6_port = htons((u_int16_t)receiver->sFlowRcvrPort);
	sa6->sin6_family = AF_INET6;
	sa6->sin6_addr = receiver->sFlowRcvrAddress.address.ip_v6;
    }
    else {
	struct sockaddr_in *sa4 = &receiver->receiver4;
	sa4->sin_port = htons((u_int16_t)receiver->sFlowRcvrPort);
	sa4->sin_family = AF_INET;
	sa4->sin_addr = receiver->sFlowRcvrAddress.address.ip_v4;
    }
}
#endif

/*_________________----------------------------------------_____________
  _________________          MIB Vars                      _____________
  -----------------________________________________________-------------
*/

char * sfl_receiver_get_sFlowRcvrOwner(SFLReceiver *receiver) {
    return receiver->sFlowRcvrOwner;
}
void sfl_receiver_set_sFlowRcvrOwner(SFLReceiver *receiver, char *sFlowRcvrOwner) {
    receiver->sFlowRcvrOwner = sFlowRcvrOwner;
    if(sFlowRcvrOwner == NULL || sFlowRcvrOwner[0] == '\0') {
	// reset condition! owner string was cleared
	reset(receiver);
    }
}
time_t sfl_receiver_get_sFlowRcvrTimeout(SFLReceiver *receiver) {
    return receiver->sFlowRcvrTimeout;
}
void sfl_receiver_set_sFlowRcvrTimeout(SFLReceiver *receiver, time_t sFlowRcvrTimeout) {
    receiver->sFlowRcvrTimeout =sFlowRcvrTimeout;
}
u_int32_t sfl_receiver_get_sFlowRcvrMaximumDatagramSize(SFLReceiver *receiver) {
    return receiver->sFlowRcvrMaximumDatagramSize;
}
void sfl_receiver_set_sFlowRcvrMaximumDatagramSize(SFLReceiver *receiver, u_int32_t sFlowRcvrMaximumDatagramSize) {
    u_int32_t mdz = sFlowRcvrMaximumDatagramSize;
    if(mdz < SFL_MIN_DATAGRAM_SIZE) mdz = SFL_MIN_DATAGRAM_SIZE;
    receiver->sFlowRcvrMaximumDatagramSize = mdz;
}
SFLAddress *sfl_receiver_get_sFlowRcvrAddress(SFLReceiver *receiver) {
    return &receiver->sFlowRcvrAddress;
}
void sfl_receiver_set_sFlowRcvrAddress(SFLReceiver *receiver, SFLAddress *sFlowRcvrAddress) {
    if(sFlowRcvrAddress) receiver->sFlowRcvrAddress = *sFlowRcvrAddress; // structure copy
#ifdef SFLOW_DO_SOCKET
    initSocket(receiver);
#endif
}
u_int32_t sfl_receiver_get_sFlowRcvrPort(SFLReceiver *receiver) {
    return receiver->sFlowRcvrPort;
}
void sfl_receiver_set_sFlowRcvrPort(SFLReceiver *receiver, u_int32_t sFlowRcvrPort) {
    receiver->sFlowRcvrPort = sFlowRcvrPort;
    // update the socket structure
#ifdef SFLOW_DO_SOCKET
    initSocket(receiver);
#endif
}

/*_________________---------------------------__________________
  _________________   sfl_receiver_tick       __________________
  -----------------___________________________------------------
*/

void sfl_receiver_tick(SFLReceiver *receiver, time_t now)
{
    // if there are any samples to send, flush them now
    if(receiver->sampleCollector.numSamples > 0) sendSample(receiver);
    // check the timeout
    if(receiver->sFlowRcvrTimeout && (u_int32_t)receiver->sFlowRcvrTimeout != 0xFFFFFFFF) {
	// count down one tick and reset if we reach 0
	if(--receiver->sFlowRcvrTimeout == 0) reset(receiver);
    }
}

/*_________________-----------------------------__________________
  _________________   receiver write utilities  __________________
  -----------------_____________________________------------------
*/

inline static void put32(SFLReceiver *receiver, u_int32_t val)
{
    *receiver->sampleCollector.datap++ = val;
}

inline static void putNet32(SFLReceiver *receiver, u_int32_t val)
{
    *receiver->sampleCollector.datap++ = htonl(val);
}

inline static void putNet32_run(SFLReceiver *receiver, void *obj, size_t quads)
{
    u_int32_t *from = (u_int32_t *)obj;
    while(quads--) putNet32(receiver, *from++);
}

inline static void putNet64(SFLReceiver *receiver, u_int64_t val64)
{
    u_int32_t *firstQuadPtr = receiver->sampleCollector.datap;
    // first copy the bytes in
    memcpy((u_char *)firstQuadPtr, &val64, 8);
    if(htonl(1) != 1) {
	// swap the bytes, and reverse the quads too
	u_int32_t tmp = *receiver->sampleCollector.datap++;
	*firstQuadPtr = htonl(*receiver->sampleCollector.datap);
	*receiver->sampleCollector.datap++ = htonl(tmp);
    }
    else receiver->sampleCollector.datap += 2;
}

inline static void put128(SFLReceiver *receiver, u_char *val)
{
    memcpy(receiver->sampleCollector.datap, val, 16);
    receiver->sampleCollector.datap += 4;
}

inline static void putString(SFLReceiver *receiver, SFLString *s)
{
    putNet32(receiver, s->len);
    memcpy(receiver->sampleCollector.datap, s->str, s->len);
    receiver->sampleCollector.datap += (s->len + 3) / 4; /* pad to 4-byte boundary */
}

inline static u_int32_t stringEncodingLength(SFLString *s) {
    // answer in bytes,  so remember to mulitply by 4 after rounding up to nearest 4-byte boundary
    return 4 + (((s->len + 3) / 4) * 4);
}

inline static void putAddress(SFLReceiver *receiver, SFLAddress *addr)
{
    // encode unspecified addresses as IPV4:0.0.0.0 - or should we flag this as an error?
    if(addr->type == 0) {
	putNet32(receiver, SFLADDRESSTYPE_IP_V4);
	put32(receiver, 0);
    }
    else {
	putNet32(receiver, addr->type);
	if(addr->type == SFLADDRESSTYPE_IP_V4) put32(receiver, addr->address.ip_v4.addr);
	else put128(receiver, addr->address.ip_v6.addr);
    }
}

inline static u_int32_t addressEncodingLength(SFLAddress *addr) {
    return (addr->type == SFLADDRESSTYPE_IP_V6) ? 20 : 8;  // type + address (unspecified == IPV4)
}

inline static void putMACAddress(SFLReceiver *receiver, u_int8_t *mac)
{
    memcpy(receiver->sampleCollector.datap, mac, 6);
    receiver->sampleCollector.datap += 2;
}

inline static void putSwitch(SFLReceiver *receiver, SFLExtended_switch *sw)
{
    putNet32(receiver, sw->src_vlan);
    putNet32(receiver, sw->src_priority);
    putNet32(receiver, sw->dst_vlan);
    putNet32(receiver, sw->dst_priority);
}

inline static void putRouter(SFLReceiver *receiver, SFLExtended_router *router)
{
    putAddress(receiver, &router->nexthop);
    putNet32(receiver, router->src_mask);
    putNet32(receiver, router->dst_mask);
}

inline static u_int32_t routerEncodingLength(SFLExtended_router *router) {
    return addressEncodingLength(&router->nexthop) + 8;
}

inline static void putGateway(SFLReceiver *receiver, SFLExtended_gateway *gw)
{
    putAddress(receiver, &gw->nexthop);
    putNet32(receiver, gw->as);
    putNet32(receiver, gw->src_as);
    putNet32(receiver, gw->src_peer_as);
    putNet32(receiver, gw->dst_as_path_segments);
    {
	u_int32_t seg = 0;
	for(; seg < gw->dst_as_path_segments; seg++) {
	    putNet32(receiver, gw->dst_as_path[seg].type);
	    putNet32(receiver, gw->dst_as_path[seg].length);
	    putNet32_run(receiver, gw->dst_as_path[seg].as.seq, gw->dst_as_path[seg].length);
	}
    }
    putNet32(receiver, gw->communities_length);
    putNet32_run(receiver, gw->communities, gw->communities_length);
    putNet32(receiver, gw->localpref);
}

inline static u_int32_t gatewayEncodingLength(SFLExtended_gateway *gw) {
    u_int32_t elemSiz = addressEncodingLength(&gw->nexthop);
    u_int32_t seg = 0;
    elemSiz += 16; // as, src_as, src_peer_as, dst_as_path_segments
    for(; seg < gw->dst_as_path_segments; seg++) {
	elemSiz += 8; // type, length
	elemSiz += 4 * gw->dst_as_path[seg].length; // set/seq bytes
    }
    elemSiz += 4; // communities_length
    elemSiz += 4 * gw->communities_length; // communities
    elemSiz += 4; // localpref
    return elemSiz;
}

inline static void putUser(SFLReceiver *receiver, SFLExtended_user *user)
{
    putNet32(receiver, user->src_charset);
    putString(receiver, &user->src_user);
    putNet32(receiver, user->dst_charset);
    putString(receiver, &user->dst_user);
}

inline static u_int32_t userEncodingLength(SFLExtended_user *user) {
    return 4
	+ stringEncodingLength(&user->src_user)
	+ 4
	+ stringEncodingLength(&user->dst_user);
}

inline static void putUrl(SFLReceiver *receiver, SFLExtended_url *url)
{
    putNet32(receiver, url->direction);
    putString(receiver, &url->url);
    putString(receiver, &url->host);
}

inline static u_int32_t urlEncodingLength(SFLExtended_url *url) {
    return 4
	+ stringEncodingLength(&url->url)
	+ stringEncodingLength(&url->host);
}

inline static void putLabelStack(SFLReceiver *receiver, SFLLabelStack *labelStack)
{
    putNet32(receiver, labelStack->depth);
    putNet32_run(receiver, labelStack->stack, labelStack->depth);
}

inline static u_int32_t labelStackEncodingLength(SFLLabelStack *labelStack) {
    return 4 + (4 * labelStack->depth);
}

inline static void putMpls(SFLReceiver *receiver, SFLExtended_mpls *mpls)
{
    putAddress(receiver, &mpls->nextHop);
    putLabelStack(receiver, &mpls->in_stack);
    putLabelStack(receiver, &mpls->out_stack);
}

inline static u_int32_t mplsEncodingLength(SFLExtended_mpls *mpls) {
    return addressEncodingLength(&mpls->nextHop)
	+ labelStackEncodingLength(&mpls->in_stack)
	+ labelStackEncodingLength(&mpls->out_stack);
}

inline static void putNat(SFLReceiver *receiver, SFLExtended_nat *nat)
{
    putAddress(receiver, &nat->src);
    putAddress(receiver, &nat->dst);
}

inline static u_int32_t natEncodingLength(SFLExtended_nat *nat) {
    return addressEncodingLength(&nat->src)
	+ addressEncodingLength(&nat->dst);
}

inline static void putMplsTunnel(SFLReceiver *receiver, SFLExtended_mpls_tunnel *tunnel)
{
    putString(receiver, &tunnel->tunnel_lsp_name);
    putNet32(receiver, tunnel->tunnel_id);
    putNet32(receiver, tunnel->tunnel_cos);
}

inline static u_int32_t mplsTunnelEncodingLength(SFLExtended_mpls_tunnel *tunnel) {
    return stringEncodingLength(&tunnel->tunnel_lsp_name) + 8;
}

inline static void putMplsVc(SFLReceiver *receiver, SFLExtended_mpls_vc *vc)
{
    putString(receiver, &vc->vc_instance_name);
    putNet32(receiver, vc->vll_vc_id);
    putNet32(receiver, vc->vc_label_cos);
}

inline static u_int32_t mplsVcEncodingLength(SFLExtended_mpls_vc *vc) {
    return stringEncodingLength( &vc->vc_instance_name) + 8;
}

inline static void putMplsFtn(SFLReceiver *receiver, SFLExtended_mpls_FTN *ftn)
{
    putString(receiver, &ftn->mplsFTNDescr);
    putNet32(receiver, ftn->mplsFTNMask);
}

inline static u_int32_t mplsFtnEncodingLength(SFLExtended_mpls_FTN *ftn) {
    return stringEncodingLength( &ftn->mplsFTNDescr) + 4;
}

inline static void putMplsLdpFec(SFLReceiver *receiver, SFLExtended_mpls_LDP_FEC *ldpfec)
{
    putNet32(receiver, ldpfec->mplsFecAddrPrefixLength);
}

inline static u_int32_t mplsLdpFecEncodingLength(SFLExtended_mpls_LDP_FEC *ldpfec) {
    return 4;
}

inline static void putVlanTunnel(SFLReceiver *receiver, SFLExtended_vlan_tunnel *vlanTunnel)
{
    putLabelStack(receiver, &vlanTunnel->stack);
}

inline static u_int32_t vlanTunnelEncodingLength(SFLExtended_vlan_tunnel *vlanTunnel) {
    return labelStackEncodingLength(&vlanTunnel->stack);
}


inline static void putGenericCounters(SFLReceiver *receiver, SFLIf_counters *counters)
{
    putNet32(receiver, counters->ifIndex);
    putNet32(receiver, counters->ifType);
    putNet64(receiver, counters->ifSpeed);
    putNet32(receiver, counters->ifDirection);
    putNet32(receiver, counters->ifStatus);
    putNet64(receiver, counters->ifInOctets);
    putNet32(receiver, counters->ifInUcastPkts);
    putNet32(receiver, counters->ifInMulticastPkts);
    putNet32(receiver, counters->ifInBroadcastPkts);
    putNet32(receiver, counters->ifInDiscards);
    putNet32(receiver, counters->ifInErrors);
    putNet32(receiver, counters->ifInUnknownProtos);
    putNet64(receiver, counters->ifOutOctets);
    putNet32(receiver, counters->ifOutUcastPkts);
    putNet32(receiver, counters->ifOutMulticastPkts);
    putNet32(receiver, counters->ifOutBroadcastPkts);
    putNet32(receiver, counters->ifOutDiscards);
    putNet32(receiver, counters->ifOutErrors);
    putNet32(receiver, counters->ifPromiscuousMode);
}


/*_________________-----------------------------__________________
  _________________      computeFlowSampleSize  __________________
  -----------------_____________________________------------------
*/

static int computeFlowSampleSize(SFLReceiver *receiver, SFL_FLOW_SAMPLE_TYPE *fs)
{
    SFLFlow_sample_element *elem = fs->elements;
#ifdef SFL_USE_32BIT_INDEX
    u_int siz = 52; /* tag, length, sequence_number, ds_class, ds_index, sampling_rate,
		       sample_pool, drops, inputFormat, input, outputFormat, output, number of elements */
#else
    u_int siz = 40; /* tag, length, sequence_number, source_id, sampling_rate,
		       sample_pool, drops, input, output, number of elements */
#endif

    fs->num_elements = 0; /* we're going to count them again even if this was set by the client */
    for(; elem != NULL; elem = elem->nxt) {
	u_int elemSiz = 0;
	fs->num_elements++;
	siz += 8; /* tag, length */
	switch(elem->tag) {
	case SFLFLOW_HEADER:
	    elemSiz = 16; /* header_protocol, frame_length, stripped, header_length */
	    elemSiz += ((elem->flowType.header.header_length + 3) / 4) * 4; /* header, rounded up to nearest 4 bytes */
	    break;
	case SFLFLOW_ETHERNET: elemSiz = sizeof(SFLSampled_ethernet); break;
	case SFLFLOW_IPV4: elemSiz = sizeof(SFLSampled_ipv4); break;
	case SFLFLOW_IPV6: elemSiz = sizeof(SFLSampled_ipv6); break;
	case SFLFLOW_EX_SWITCH: elemSiz = sizeof(SFLExtended_switch); break;
	case SFLFLOW_EX_ROUTER: elemSiz = routerEncodingLength(&elem->flowType.router); break;
	case SFLFLOW_EX_GATEWAY: elemSiz = gatewayEncodingLength(&elem->flowType.gateway); break;
	case SFLFLOW_EX_USER: elemSiz = userEncodingLength(&elem->flowType.user); break;
	case SFLFLOW_EX_URL: elemSiz = urlEncodingLength(&elem->flowType.url); break;
	case SFLFLOW_EX_MPLS: elemSiz = mplsEncodingLength(&elem->flowType.mpls); break;
	case SFLFLOW_EX_NAT: elemSiz = natEncodingLength(&elem->flowType.nat); break;
	case SFLFLOW_EX_MPLS_TUNNEL: elemSiz = mplsTunnelEncodingLength(&elem->flowType.mpls_tunnel); break;
	case SFLFLOW_EX_MPLS_VC: elemSiz = mplsVcEncodingLength(&elem->flowType.mpls_vc); break;
	case SFLFLOW_EX_MPLS_FTN: elemSiz = mplsFtnEncodingLength(&elem->flowType.mpls_ftn); break;
	case SFLFLOW_EX_MPLS_LDP_FEC: elemSiz = mplsLdpFecEncodingLength(&elem->flowType.mpls_ldp_fec); break;
	case SFLFLOW_EX_VLAN_TUNNEL: elemSiz = vlanTunnelEncodingLength(&elem->flowType.vlan_tunnel); break;
	default:
	    sflError(receiver, "unexpected packet_data_tag");
	    return -1;
	    break;
	}
	// cache the element size, and accumulate it into the overall FlowSample size
	elem->length = elemSiz;
	siz += elemSiz;
    }

    return siz;
}

/*_________________-------------------------------__________________
  _________________ sfl_receiver_writeFlowSample  __________________
  -----------------_______________________________------------------
*/

int sfl_receiver_writeFlowSample(SFLReceiver *receiver, SFL_FLOW_SAMPLE_TYPE *fs)
{
    int packedSize;
    if(fs == NULL) return -1;
    if((packedSize = computeFlowSampleSize(receiver, fs)) == -1) return -1;

    // check in case this one sample alone is too big for the datagram
    // in fact - if it is even half as big then we should ditch it. Very
    // important to avoid overruning the packet buffer.
    if(packedSize > (int)(receiver->sFlowRcvrMaximumDatagramSize / 2)) {
	sflError(receiver, "flow sample too big for datagram");
	return -1;
    }

    // if the sample pkt is full enough so that this sample might put
    // it over the limit, then we should send it now before going on.
    if((receiver->sampleCollector.pktlen + packedSize) >= receiver->sFlowRcvrMaximumDatagramSize)
	sendSample(receiver);

    receiver->sampleCollector.numSamples++;

#ifdef SFL_USE_32BIT_INDEX
    putNet32(receiver, SFLFLOW_SAMPLE_EXPANDED);
#else
    putNet32(receiver, SFLFLOW_SAMPLE);
#endif

    putNet32(receiver, packedSize - 8); // don't include tag and len
    putNet32(receiver, fs->sequence_number);

#ifdef SFL_USE_32BIT_INDEX
    putNet32(receiver, fs->ds_class);
    putNet32(receiver, fs->ds_index);
#else
    putNet32(receiver, fs->source_id);
#endif

    putNet32(receiver, fs->sampling_rate);
    putNet32(receiver, fs->sample_pool);
    putNet32(receiver, fs->drops);

#ifdef SFL_USE_32BIT_INDEX
    putNet32(receiver, fs->inputFormat);
    putNet32(receiver, fs->input);
    putNet32(receiver, fs->outputFormat);
    putNet32(receiver, fs->output);
#else
    putNet32(receiver, fs->input);
    putNet32(receiver, fs->output);
#endif

    putNet32(receiver, fs->num_elements);

    {
	SFLFlow_sample_element *elem = fs->elements;
	for(; elem != NULL; elem = elem->nxt) {

	    putNet32(receiver, elem->tag);
	    putNet32(receiver, elem->length); // length cached in computeFlowSampleSize()

	    switch(elem->tag) {
	    case SFLFLOW_HEADER:
		putNet32(receiver, elem->flowType.header.header_protocol);
		putNet32(receiver, elem->flowType.header.frame_length);
		putNet32(receiver, elem->flowType.header.stripped);
		putNet32(receiver, elem->flowType.header.header_length);
		/* the header */
		memcpy(receiver->sampleCollector.datap, elem->flowType.header.header_bytes, elem->flowType.header.header_length);
		/* round up to multiple of 4 to preserve alignment */
		receiver->sampleCollector.datap += ((elem->flowType.header.header_length + 3) / 4);
		break;
	    case SFLFLOW_ETHERNET:
		putNet32(receiver, elem->flowType.ethernet.eth_len);
		putMACAddress(receiver, elem->flowType.ethernet.src_mac);
		putMACAddress(receiver, elem->flowType.ethernet.dst_mac);
		putNet32(receiver, elem->flowType.ethernet.eth_type);
		break;
	    case SFLFLOW_IPV4:
		putNet32(receiver, elem->flowType.ipv4.length);
		putNet32(receiver, elem->flowType.ipv4.protocol);
		put32(receiver, elem->flowType.ipv4.src_ip.addr);
		put32(receiver, elem->flowType.ipv4.dst_ip.addr);
		putNet32(receiver, elem->flowType.ipv4.src_port);
		putNet32(receiver, elem->flowType.ipv4.dst_port);
		putNet32(receiver, elem->flowType.ipv4.tcp_flags);
		putNet32(receiver, elem->flowType.ipv4.tos);
		break;
	    case SFLFLOW_IPV6:
		putNet32(receiver, elem->flowType.ipv6.length);
		putNet32(receiver, elem->flowType.ipv6.protocol);
		put128(receiver, elem->flowType.ipv6.src_ip.addr);
		put128(receiver, elem->flowType.ipv6.dst_ip.addr);
		putNet32(receiver, elem->flowType.ipv6.src_port);
		putNet32(receiver, elem->flowType.ipv6.dst_port);
		putNet32(receiver, elem->flowType.ipv6.tcp_flags);
		putNet32(receiver, elem->flowType.ipv6.priority);
		break;
	    case SFLFLOW_EX_SWITCH: putSwitch(receiver, &elem->flowType.sw); break;
	    case SFLFLOW_EX_ROUTER: putRouter(receiver, &elem->flowType.router); break;
	    case SFLFLOW_EX_GATEWAY: putGateway(receiver, &elem->flowType.gateway); break;
	    case SFLFLOW_EX_USER: putUser(receiver, &elem->flowType.user); break;
	    case SFLFLOW_EX_URL: putUrl(receiver, &elem->flowType.url); break;
	    case SFLFLOW_EX_MPLS: putMpls(receiver, &elem->flowType.mpls); break;
	    case SFLFLOW_EX_NAT: putNat(receiver, &elem->flowType.nat); break;
	    case SFLFLOW_EX_MPLS_TUNNEL: putMplsTunnel(receiver, &elem->flowType.mpls_tunnel); break;
	    case SFLFLOW_EX_MPLS_VC: putMplsVc(receiver, &elem->flowType.mpls_vc); break;
	    case SFLFLOW_EX_MPLS_FTN: putMplsFtn(receiver, &elem->flowType.mpls_ftn); break;
	    case SFLFLOW_EX_MPLS_LDP_FEC: putMplsLdpFec(receiver, &elem->flowType.mpls_ldp_fec); break;
	    case SFLFLOW_EX_VLAN_TUNNEL: putVlanTunnel(receiver, &elem->flowType.vlan_tunnel); break;
	    default:
		sflError(receiver, "unexpected packet_data_tag");
		return -1;
		break;
	    }
	}
    }

    // sanity check
    assert(((u_char *)receiver->sampleCollector.datap
	    - (u_char *)receiver->sampleCollector.data
	    - receiver->sampleCollector.pktlen)  == (u_int32_t)packedSize);

    // update the pktlen
    receiver->sampleCollector.pktlen = (u_char *)receiver->sampleCollector.datap - (u_char *)receiver->sampleCollector.data;
    return packedSize;
}

/*_________________-----------------------------__________________
  _________________ computeCountersSampleSize   __________________
  -----------------_____________________________------------------
*/

static int computeCountersSampleSize(SFLReceiver *receiver, SFL_COUNTERS_SAMPLE_TYPE *cs)
{
    SFLCounters_sample_element *elem = cs->elements;
#ifdef SFL_USE_32BIT_INDEX
    u_int siz = 24; /* tag, length, sequence_number, ds_class, ds_index, number of elements */
#else
    u_int siz = 20; /* tag, length, sequence_number, source_id, number of elements */
#endif

    cs->num_elements = 0; /* we're going to count them again even if this was set by the client */
    for(; elem != NULL; elem = elem->nxt) {
	u_int elemSiz = 0;
	cs->num_elements++;
	siz += 8; /* tag, length */
	switch(elem->tag) {
	case SFLCOUNTERS_GENERIC:  elemSiz = sizeof(elem->counterBlock.generic); break;
	case SFLCOUNTERS_ETHERNET: elemSiz = sizeof(elem->counterBlock.ethernet); break;
	case SFLCOUNTERS_TOKENRING: elemSiz = sizeof(elem->counterBlock.tokenring); break;
	case SFLCOUNTERS_VG: elemSiz = sizeof(elem->counterBlock.vg); break;
	case SFLCOUNTERS_VLAN: elemSiz = sizeof(elem->counterBlock.vlan); break;
	default:
	    sflError(receiver, "unexpected counters_tag");
	    return -1;
	    break;
	}
	// cache the element size, and accumulate it into the overall FlowSample size
	elem->length = elemSiz;
	siz += elemSiz;
    }
    return siz;
}

/*_________________----------------------------------__________________
  _________________ sfl_receiver_writeCountersSample __________________
  -----------------__________________________________------------------
*/

int sfl_receiver_writeCountersSample(SFLReceiver *receiver, SFL_COUNTERS_SAMPLE_TYPE *cs)
{
    int packedSize;
    if(cs == NULL) return -1;
    // if the sample pkt is full enough so that this sample might put
    // it over the limit, then we should send it now.
    if((packedSize = computeCountersSampleSize(receiver, cs)) == -1) return -1;

    // check in case this one sample alone is too big for the datagram
    // in fact - if it is even half as big then we should ditch it. Very
    // important to avoid overruning the packet buffer.
    if(packedSize > (int)(receiver->sFlowRcvrMaximumDatagramSize / 2)) {
	sflError(receiver, "counters sample too big for datagram");
	return -1;
    }

    if((receiver->sampleCollector.pktlen + packedSize) >= receiver->sFlowRcvrMaximumDatagramSize)
	sendSample(receiver);

    receiver->sampleCollector.numSamples++;

#ifdef SFL_USE_32BIT_INDEX
    putNet32(receiver, SFLCOUNTERS_SAMPLE_EXPANDED);
#else
    putNet32(receiver, SFLCOUNTERS_SAMPLE);
#endif

    putNet32(receiver, packedSize - 8); // tag and length not included
    putNet32(receiver, cs->sequence_number);

#ifdef SFL_USE_32BIT_INDEX
    putNet32(receiver, cs->ds_class);
    putNet32(receiver, cs->ds_index);
#else
    putNet32(receiver, cs->source_id);
#endif

    putNet32(receiver, cs->num_elements);

    {
	SFLCounters_sample_element *elem = cs->elements;
	for(; elem != NULL; elem = elem->nxt) {

	    putNet32(receiver, elem->tag);
	    putNet32(receiver, elem->length); // length cached in computeCountersSampleSize()

	    switch(elem->tag) {
	    case SFLCOUNTERS_GENERIC:
		putGenericCounters(receiver, &(elem->counterBlock.generic));
		break;
	    case SFLCOUNTERS_ETHERNET:
		// all these counters are 32-bit
		putNet32_run(receiver, &elem->counterBlock.ethernet, sizeof(elem->counterBlock.ethernet) / 4);
		break;
	    case SFLCOUNTERS_TOKENRING:
		// all these counters are 32-bit
		putNet32_run(receiver, &elem->counterBlock.tokenring, sizeof(elem->counterBlock.tokenring) / 4);
		break;
	    case SFLCOUNTERS_VG:
		// mixed sizes
		putNet32(receiver, elem->counterBlock.vg.dot12InHighPriorityFrames);
		putNet64(receiver, elem->counterBlock.vg.dot12InHighPriorityOctets);
		putNet32(receiver, elem->counterBlock.vg.dot12InNormPriorityFrames);
		putNet64(receiver, elem->counterBlock.vg.dot12InNormPriorityOctets);
		putNet32(receiver, elem->counterBlock.vg.dot12InIPMErrors);
		putNet32(receiver, elem->counterBlock.vg.dot12InOversizeFrameErrors);
		putNet32(receiver, elem->counterBlock.vg.dot12InDataErrors);
		putNet32(receiver, elem->counterBlock.vg.dot12InNullAddressedFrames);
		putNet32(receiver, elem->counterBlock.vg.dot12OutHighPriorityFrames);
		putNet64(receiver, elem->counterBlock.vg.dot12OutHighPriorityOctets);
		putNet32(receiver, elem->counterBlock.vg.dot12TransitionIntoTrainings);
		putNet64(receiver, elem->counterBlock.vg.dot12HCInHighPriorityOctets);
		putNet64(receiver, elem->counterBlock.vg.dot12HCInNormPriorityOctets);
		putNet64(receiver, elem->counterBlock.vg.dot12HCOutHighPriorityOctets);
		break;
	    case SFLCOUNTERS_VLAN:
		// mixed sizes
		putNet32(receiver, elem->counterBlock.vlan.vlan_id);
		putNet64(receiver, elem->counterBlock.vlan.octets);
		putNet32(receiver, elem->counterBlock.vlan.ucastPkts);
		putNet32(receiver, elem->counterBlock.vlan.multicastPkts);
		putNet32(receiver, elem->counterBlock.vlan.broadcastPkts);
		putNet32(receiver, elem->counterBlock.vlan.discards);
		break;
	    default:
		sflError(receiver, "unexpected counters_tag");
		return -1;
		break;
	    }
	}
    }
    // sanity check
    assert(((u_char *)receiver->sampleCollector.datap
	    - (u_char *)receiver->sampleCollector.data
	    - receiver->sampleCollector.pktlen)  == (u_int32_t)packedSize);

    // update the pktlen
    receiver->sampleCollector.pktlen = (u_char *)receiver->sampleCollector.datap - (u_char *)receiver->sampleCollector.data;
    return packedSize;
}

/*_________________---------------------------------__________________
  _________________ sfl_receiver_samplePacketsSent  __________________
  -----------------_________________________________------------------
*/

u_int32_t sfl_receiver_samplePacketsSent(SFLReceiver *receiver)
{
    return receiver->sampleCollector.packetSeqNo;
}

/*_________________---------------------------__________________
  _________________     sendSample            __________________
  -----------------___________________________------------------
*/

static void sendSample(SFLReceiver *receiver)
{
    /* construct and send out the sample, then reset for the next one... */
    /* first fill in the header with the latest values */
    /* version, agent_address and sub_agent_id were pre-set. */
    u_int32_t hdrIdx = (receiver->agent->myIP.type == SFLADDRESSTYPE_IP_V6) ? 7 : 4;
    receiver->sampleCollector.data[hdrIdx++] = htonl(++receiver->sampleCollector.packetSeqNo); /* seq no */
    receiver->sampleCollector.data[hdrIdx++] = htonl((receiver->agent->now - receiver->agent->bootTime) * 1000); /* uptime */
    receiver->sampleCollector.data[hdrIdx++] = htonl(receiver->sampleCollector.numSamples); /* num samples */
    /* send */
    if(receiver->agent->sendFn) (*receiver->agent->sendFn)(receiver->agent->magic,
							   receiver->agent,
							   receiver,
							   (u_char *)receiver->sampleCollector.data,
							   receiver->sampleCollector.pktlen);
    else {
#ifdef SFLOW_DO_SOCKET
	/* send it myself */
	if (receiver->sFlowRcvrAddress.type == SFLADDRESSTYPE_IP_V6) {
	    u_int32_t soclen = sizeof(struct sockaddr_in6);
	    int result = sendto(receiver->agent->receiverSocket6,
				receiver->sampleCollector.data,
				receiver->sampleCollector.pktlen,
				0,
				(struct sockaddr *)&receiver->receiver6,
				soclen);
	    if(result == -1 && errno != EINTR) sfl_agent_sysError(receiver->agent, "receiver", "IPv6 socket sendto error");
	    if(result == 0) sfl_agent_error(receiver->agent, "receiver", "IPv6 socket sendto returned 0");
	}
	else {
	    u_int32_t soclen = sizeof(struct sockaddr_in);
	    int result = sendto(receiver->agent->receiverSocket4,
				receiver->sampleCollector.data,
				receiver->sampleCollector.pktlen,
				0,
				(struct sockaddr *)&receiver->receiver4,
				soclen);
	    if(result == -1 && errno != EINTR) sfl_agent_sysError(receiver->agent, "receiver", "socket sendto error");
	    if(result == 0) sfl_agent_error(receiver->agent, "receiver", "socket sendto returned 0");
	}
#endif
    }

    /* reset for the next time */
    resetSampleCollector(receiver);
}

/*_________________---------------------------__________________
  _________________   resetSampleCollector    __________________
  -----------------___________________________------------------
*/

static void resetSampleCollector(SFLReceiver *receiver)
{
    receiver->sampleCollector.pktlen = 0;
    receiver->sampleCollector.numSamples = 0;
    /* point the datap to just after the header */
    receiver->sampleCollector.datap = (receiver->agent->myIP.type == SFLADDRESSTYPE_IP_V6) ?
	(receiver->sampleCollector.data + 10) :  (receiver->sampleCollector.data + 7);

    receiver->sampleCollector.pktlen = (u_char *)receiver->sampleCollector.datap - (u_char *)receiver->sampleCollector.data;
}

/*_________________---------------------------__________________
  _________________         sflError          __________________
  -----------------___________________________------------------
*/

static void sflError(SFLReceiver *receiver, char *msg)
{
    sfl_agent_error(receiver->agent, "receiver", msg);
    resetSampleCollector(receiver);
}

#endif  /* !__CHECKER__ */