teems/Enclave/route.cpp

#include "Enclave_t.h"
#include "config.hpp"
#include "utils.hpp"
#include "sort.hpp"
#include "comms.hpp"
#include "obliv.hpp"
#include "storage.hpp"
#include "route.hpp"

#define PROFILE_ROUTING

enum RouteStep {
    ROUTE_NOT_STARTED,
    ROUTE_ROUND_1,
    ROUTE_ROUND_2
};

// The ingbuf MsgBuffer stores messages an ingestion node ingests while
// waiting for round 1 to start, which will be sorted and sent out in
// round 1.  The round1 MsgBuffer stores messages a routing node
// receives in round 1, which will be padded, sorted, and sent out in
// round 2.  The round2 MsgBuffer stores messages a storage node
// receives in round 2.

static struct RouteState {
    MsgBuffer ingbuf;
    MsgBuffer round1;
    MsgBuffer round2;
    RouteStep step;
    uint32_t tot_msg_per_ing;
    uint32_t max_msg_to_each_stg;
    uint32_t max_round2_msgs;
    uint32_t max_stg_msgs;
    void *cbpointer;
} route_state;

// Computes ceil(x/y) where x and y are integers, x>=0, y>0.

#define CEILDIV(x,y) (((x)+(y)-1)/(y))

// Call this near the end of ecall_config_load, but before
// comms_init_nodestate. Returns true on success, false on failure.
bool route_init()
{
    // Compute the maximum number of messages we could receive by direct
    // ingestion

    // Each ingestion node will have at most
    // ceil(user_count/num_ingestion_nodes) users, and each user will
    // send at most m_priv_out messages.
    uint32_t users_per_ing = CEILDIV(g_teems_config.user_count,
        g_teems_config.num_ingestion_nodes);
    uint32_t tot_msg_per_ing = users_per_ing * g_teems_config.m_priv_out;

    // Compute the maximum number of messages we could receive in round 1
    // Each ingestion node will send us an our_weight/tot_weight
    // fraction of the messages they hold
    uint32_t max_msg_from_each_ing = CEILDIV(tot_msg_per_ing,
        g_teems_config.tot_weight) * g_teems_config.my_weight;

    // And the maximum number we can receive in total is that times the
    // number of ingestion nodes
    uint32_t max_round1_msgs = max_msg_from_each_ing *
        g_teems_config.num_ingestion_nodes;

    // Compute the maximum number of messages we could send in round 2

    // Each storage node has at most this many users
    uint32_t users_per_stg = CEILDIV(g_teems_config.user_count,
        g_teems_config.num_storage_nodes);

    // And so can receive at most this many messages
    uint32_t tot_msg_per_stg = users_per_stg *
        g_teems_config.m_priv_in;

    // Which will be at most this many from us
    uint32_t max_msg_to_each_stg = CEILDIV(tot_msg_per_stg,
        g_teems_config.tot_weight) * g_teems_config.my_weight;

    // But we can't send more messages to each storage server than we
    // could receive in total
    if (max_msg_to_each_stg > max_round1_msgs) {
        max_msg_to_each_stg = max_round1_msgs;
    }

    // And the max total number of outgoing messages in round 2 is then
    uint32_t max_round2_msgs = max_msg_to_each_stg *
        g_teems_config.num_storage_nodes;

    // In case we have a weird configuration where users can send more
    // messages per epoch than they can receive, ensure the round 2
    // buffer is large enough to hold the incoming messages as well
    if (max_round2_msgs < max_round1_msgs) {
        max_round2_msgs = max_round1_msgs;
    }

    // The max number of messages that can arrive at a storage server
    uint32_t max_stg_msgs = tot_msg_per_stg + g_teems_config.tot_weight;

    /*
    printf("users_per_ing=%u, tot_msg_per_ing=%u, max_msg_from_each_ing=%u, max_round1_msgs=%u, users_per_stg=%u, tot_msg_per_stg=%u, max_msg_to_each_stg=%u, max_round2_msgs=%u, max_stg_msgs=%u\n", users_per_ing, tot_msg_per_ing, max_msg_from_each_ing, max_round1_msgs, users_per_stg, tot_msg_per_stg, max_msg_to_each_stg, max_round2_msgs, max_stg_msgs);
    */

    // Create the route state
    uint8_t my_roles = g_teems_config.roles[g_teems_config.my_node_num];
    try {
        if (my_roles & ROLE_INGESTION) {
            route_state.ingbuf.alloc(tot_msg_per_ing);
        }
        if (my_roles & ROLE_ROUTING) {
            route_state.round1.alloc(max_round2_msgs);
        }
        if (my_roles & ROLE_STORAGE) {
            route_state.round2.alloc(max_stg_msgs);
            if (!storage_init(users_per_stg, max_stg_msgs)) {
                return false;
            }
        }
    } catch (std::bad_alloc&) {
        printf("Memory allocation failed in route_init\n");
        return false;
    }
    route_state.step = ROUTE_NOT_STARTED;
    route_state.tot_msg_per_ing = tot_msg_per_ing;
    route_state.max_msg_to_each_stg = max_msg_to_each_stg;
    route_state.max_round2_msgs = max_round2_msgs;
    route_state.max_stg_msgs = max_stg_msgs;
    route_state.cbpointer = NULL;

    threadid_t nthreads = g_teems_config.nthreads;
#ifdef PROFILE_ROUTING
    unsigned long start = printf_with_rtclock("begin precompute evalplans (%u,%hu) (%u,%hu)\n", tot_msg_per_ing, nthreads, max_round2_msgs, nthreads);
#endif
    sort_precompute_evalplan(tot_msg_per_ing, nthreads);
    sort_precompute_evalplan(max_round2_msgs, nthreads);
#ifdef PROFILE_ROUTING
    printf_with_rtclock_diff(start, "end precompute evalplans\n");
#endif
    return true;
}

// Precompute the WaksmanNetworks needed for the sorts.  If you pass -1,
// it will return the number of different sizes it needs to regenerate.
// If you pass [0,sizes-1], it will compute one WaksmanNetwork with that
// size index and return the number of available WaksmanNetworks of that
// size.  If you pass anything else, it will return the number of
// different sizes it needs at all.

// The list of sizes that need refilling, updated when you pass -1
static std::vector<uint32_t> used_sizes;

size_t ecall_precompute_sort(int sizeidx)
{
    size_t ret = 0;

    if (sizeidx == -1) {
        used_sizes = sort_get_used();
        ret = used_sizes.size();
    } else if (sizeidx >= 0 && sizeidx < used_sizes.size()) {
        uint32_t size = used_sizes[sizeidx];
#ifdef PROFILE_ROUTING
        unsigned long start = printf_with_rtclock("begin precompute WaksmanNetwork (%u)\n", size);
#endif
        ret = sort_precompute(size);
#ifdef PROFILE_ROUTING
        printf_with_rtclock_diff(start, "end precompute Waksman Network (%u)\n", size);
#endif
    } else {
        uint8_t my_roles = g_teems_config.roles[g_teems_config.my_node_num];

        if (my_roles & ROLE_INGESTION) {
            used_sizes.push_back(route_state.tot_msg_per_ing);
        }
        if (my_roles & ROLE_ROUTING) {
            used_sizes.push_back(route_state.max_round2_msgs);
        }
        if (my_roles & ROLE_STORAGE) {
            used_sizes.push_back(route_state.max_stg_msgs);
        }
        ret = used_sizes.size();
    }
    return ret;
}

static uint8_t* msgbuffer_get_buf(MsgBuffer &msgbuf,
        NodeCommState &, uint32_t tot_enc_chunk_size)
{
    uint16_t msg_size = g_teems_config.msg_size;

    // Chunks will be encrypted and have a MAC tag attached which will
    // not correspond to plaintext bytes, so we can trim them.

    // The minimum number of chunks needed to transmit this message
    uint32_t min_num_chunks =
        (tot_enc_chunk_size + (FRAME_SIZE-1)) / FRAME_SIZE;
    // The number of plaintext bytes this message could contain
    uint32_t plaintext_bytes = tot_enc_chunk_size -
        SGX_AESGCM_MAC_SIZE * min_num_chunks;

    assert ((plaintext_bytes % uint32_t(msg_size)) == 0);

    uint32_t num_msgs = plaintext_bytes/uint32_t(msg_size);

    pthread_mutex_lock(&msgbuf.mutex);
    uint32_t start = msgbuf.reserved;
    if (start + num_msgs > msgbuf.bufsize) {
        pthread_mutex_unlock(&msgbuf.mutex);
        printf("Max %u messages exceeded\n", msgbuf.bufsize);
        return NULL;
    }
    msgbuf.reserved += num_msgs;
    pthread_mutex_unlock(&msgbuf.mutex);

    return msgbuf.buf + start * msg_size;
}

static void round2_received(NodeCommState &nodest,
    uint8_t *data, uint32_t plaintext_len, uint32_t);

// A round 1 message was received by a routing node from an ingestion
// node; we put it into the round 2 buffer for processing in round 2
static void round1_received(NodeCommState &nodest,
    uint8_t *data, uint32_t plaintext_len, uint32_t)
{
    uint16_t msg_size = g_teems_config.msg_size;
    assert((plaintext_len % uint32_t(msg_size)) == 0);
    uint32_t num_msgs = plaintext_len / uint32_t(msg_size);
    uint8_t our_roles = g_teems_config.roles[g_teems_config.my_node_num];
    uint8_t their_roles = g_teems_config.roles[nodest.node_num];

    pthread_mutex_lock(&route_state.round1.mutex);
    route_state.round1.inserted += num_msgs;
    route_state.round1.nodes_received += 1;
    nodenum_t nodes_received = route_state.round1.nodes_received;
    bool completed_prev_round = route_state.round1.completed_prev_round;
    pthread_mutex_unlock(&route_state.round1.mutex);

    // What is the next message we expect from this node?
    if ((our_roles & ROLE_STORAGE) && (their_roles & ROLE_ROUTING)) {
        nodest.in_msg_get_buf = [&](NodeCommState &commst,
                uint32_t tot_enc_chunk_size) {
            return msgbuffer_get_buf(route_state.round2, commst,
                tot_enc_chunk_size);
        };
        nodest.in_msg_received = round2_received;
    }
    // Otherwise, it's just the next round 1 message, so don't change
    // the handlers.

    if (nodes_received == g_teems_config.num_ingestion_nodes &&
            completed_prev_round) {
        route_state.step = ROUTE_ROUND_1;
        void *cbpointer = route_state.cbpointer;
        route_state.cbpointer = NULL;
        ocall_routing_round_complete(cbpointer, 1);
    }
}

// A round 2 message was received by a storage node from a routing node
static void round2_received(NodeCommState &nodest,
    uint8_t *data, uint32_t plaintext_len, uint32_t)
{
    uint16_t msg_size = g_teems_config.msg_size;
    assert((plaintext_len % uint32_t(msg_size)) == 0);
    uint32_t num_msgs = plaintext_len / uint32_t(msg_size);
    uint8_t our_roles = g_teems_config.roles[g_teems_config.my_node_num];
    uint8_t their_roles = g_teems_config.roles[nodest.node_num];

    pthread_mutex_lock(&route_state.round2.mutex);
    route_state.round2.inserted += num_msgs;
    route_state.round2.nodes_received += 1;
    nodenum_t nodes_received = route_state.round2.nodes_received;
    bool completed_prev_round = route_state.round2.completed_prev_round;
    pthread_mutex_unlock(&route_state.round2.mutex);

    // What is the next message we expect from this node?
    if ((our_roles & ROLE_ROUTING) && (their_roles & ROLE_INGESTION)) {
        nodest.in_msg_get_buf = [&](NodeCommState &commst,
                uint32_t tot_enc_chunk_size) {
            return msgbuffer_get_buf(route_state.round1, commst,
                tot_enc_chunk_size);
        };
        nodest.in_msg_received = round1_received;
    }
    // Otherwise, it's just the next round 2 message, so don't change
    // the handlers.

    if (nodes_received == g_teems_config.num_routing_nodes &&
            completed_prev_round) {
        route_state.step = ROUTE_ROUND_2;
        void *cbpointer = route_state.cbpointer;
        route_state.cbpointer = NULL;
        ocall_routing_round_complete(cbpointer, 2);
    }
}

// For a given other node, set the received message handler to the first
// message we would expect from them, given their roles and our roles.
void route_init_msg_handler(nodenum_t node_num)
{
    // Our roles and their roles
    uint8_t our_roles = g_teems_config.roles[g_teems_config.my_node_num];
    uint8_t their_roles = g_teems_config.roles[node_num];

    // The node communication state
    NodeCommState &nodest = g_commstates[node_num];

    // If we are a routing node (possibly among other roles) and they
    // are an ingestion node (possibly among other roles), a round 1
    // routing message is the first thing we expect from them.  We put
    // these messages into the round1 buffer for processing.
    if ((our_roles & ROLE_ROUTING) && (their_roles & ROLE_INGESTION)) {
        nodest.in_msg_get_buf = [&](NodeCommState &commst,
                uint32_t tot_enc_chunk_size) {
            return msgbuffer_get_buf(route_state.round1, commst,
                tot_enc_chunk_size);
        };
        nodest.in_msg_received = round1_received;
    }
    // Otherwise, if we are a storage node (possibly among other roles)
    // and they are a routing node (possibly among other roles), a round
    // 2 routing message is the first thing we expect from them
    else if ((our_roles & ROLE_STORAGE) && (their_roles & ROLE_ROUTING)) {
        nodest.in_msg_get_buf = [&](NodeCommState &commst,
                uint32_t tot_enc_chunk_size) {
            return msgbuffer_get_buf(route_state.round2, commst,
                tot_enc_chunk_size);
        };
        nodest.in_msg_received = round2_received;
    }
    // Otherwise, we don't expect a message from this node. Set the
    // unknown message handler.
    else {
        nodest.in_msg_get_buf = default_in_msg_get_buf;
        nodest.in_msg_received = unknown_in_msg_received;
    }
}

// Directly ingest a buffer of num_msgs messages into the ingbuf buffer.
// Return true on success, false on failure.
bool ecall_ingest_raw(uint8_t *msgs, uint32_t num_msgs)
{
    uint16_t msg_size = g_teems_config.msg_size;
    MsgBuffer &ingbuf = route_state.ingbuf;

    pthread_mutex_lock(&ingbuf.mutex);
    uint32_t start = ingbuf.reserved;
    if (start + num_msgs > route_state.tot_msg_per_ing) {
        pthread_mutex_unlock(&ingbuf.mutex);
        printf("Max %u messages exceeded\n",
            route_state.tot_msg_per_ing);
        return false;
    }
    ingbuf.reserved += num_msgs;
    pthread_mutex_unlock(&ingbuf.mutex);

    memmove(ingbuf.buf + start * msg_size,
        msgs, num_msgs * msg_size);

    pthread_mutex_lock(&ingbuf.mutex);
    ingbuf.inserted += num_msgs;
    pthread_mutex_unlock(&ingbuf.mutex);

    return true;
}

// Send the round 1 messages.  Note that N here is not private.
static void send_round1_msgs(const uint8_t *msgs, const UidKey *indices,
    uint32_t N)
{
    uint16_t msg_size = g_teems_config.msg_size;
    uint16_t tot_weight = g_teems_config.tot_weight;
    nodenum_t my_node_num = g_teems_config.my_node_num;

    uint32_t full_rows = N / uint32_t(tot_weight);
    uint32_t last_row = N % uint32_t(tot_weight);

    for (auto &routing_node: g_teems_config.routing_nodes) {
        uint8_t weight =
            g_teems_config.weights[routing_node].weight;
        if (weight == 0) {
            // This shouldn't happen, but just in case
            continue;
        }
        uint16_t start_weight =
            g_teems_config.weights[routing_node].startweight;

        // The number of messages headed for this routing node from the
        // full rows
        uint32_t num_msgs_full_rows = full_rows * uint32_t(weight);
        // The number of messages headed for this routing node from the
        // incomplete last row is:
        // 0 if last_row < start_weight
        // last_row-start_weight if start_weight <= last_row < start_weight + weight
        // weight if start_weight + weight <= last_row
        uint32_t num_msgs_last_row = 0;
        if (start_weight <= last_row && last_row < start_weight + weight) {
            num_msgs_last_row = last_row-start_weight;
        } else if (start_weight + weight <= last_row) {
            num_msgs_last_row = weight;
        }
        // The total number of messages headed for this routing node
        uint32_t num_msgs = num_msgs_full_rows + num_msgs_last_row;

        if (routing_node == my_node_num) {
            // Special case: we're sending to ourselves; just put the
            // messages in our own round1 buffer
            MsgBuffer &round1 = route_state.round1;

            pthread_mutex_lock(&round1.mutex);
            uint32_t start = round1.reserved;
            if (start + num_msgs > round1.bufsize) {
                pthread_mutex_unlock(&round1.mutex);
                printf("Max %u messages exceeded\n", round1.bufsize);
                return;
            }
            round1.reserved += num_msgs;
            pthread_mutex_unlock(&round1.mutex);
            uint8_t *buf = round1.buf + start * msg_size;

            for (uint32_t i=0; i<full_rows; ++i) {
                const UidKey *idxp = indices + i*tot_weight + start_weight;
                for (uint32_t j=0; j<weight; ++j) {
                    memmove(buf, msgs + idxp[j].index()*msg_size, msg_size);
                    buf += msg_size;
                }
            }
            const UidKey *idxp = indices + full_rows*tot_weight + start_weight;
            for (uint32_t j=0; j<num_msgs_last_row; ++j) {
                memmove(buf, msgs + idxp[j].index()*msg_size, msg_size);
                buf += msg_size;
            }

            pthread_mutex_lock(&round1.mutex);
            round1.inserted += num_msgs;
            round1.nodes_received += 1;
            pthread_mutex_unlock(&round1.mutex);

        } else {
            NodeCommState &nodecom = g_commstates[routing_node];
            nodecom.message_start(num_msgs * msg_size);
            for (uint32_t i=0; i<full_rows; ++i) {
                const UidKey *idxp = indices + i*tot_weight + start_weight;
                for (uint32_t j=0; j<weight; ++j) {
                    nodecom.message_data(msgs + idxp[j].index()*msg_size, msg_size);
                }
            }
            const UidKey *idxp = indices + full_rows*tot_weight + start_weight;
            for (uint32_t j=0; j<num_msgs_last_row; ++j) {
                nodecom.message_data(msgs + idxp[j].index()*msg_size, msg_size);
            }
        }
    }
}

// Send the round 2 messages from the round 1 buffer, which are already
// padded and shuffled, so this can be done non-obliviously.  tot_msgs
// is the total number of messages in the input buffer, which may
// include padding messages added by the shuffle.  Those messages are
// not sent anywhere.  There are num_msgs_per_stg messages for each
// storage node labelled for that node.
static void send_round2_msgs(uint32_t tot_msgs, uint32_t num_msgs_per_stg)
{
    uint16_t msg_size = g_teems_config.msg_size;
    MsgBuffer &round1 = route_state.round1;
    const uint8_t* buf = round1.buf;
    nodenum_t num_storage_nodes = g_teems_config.num_storage_nodes;
    nodenum_t my_node_num = g_teems_config.my_node_num;
    uint8_t *myself_buf = NULL;

    for (nodenum_t i=0; i<num_storage_nodes; ++i) {
        nodenum_t node = g_teems_config.storage_nodes[i];
        if (node != my_node_num) {
            g_commstates[node].message_start(msg_size * num_msgs_per_stg);
        } else {
            MsgBuffer &round2 = route_state.round2;
            pthread_mutex_lock(&round2.mutex);
            uint32_t start = round2.reserved;
            if (start + num_msgs_per_stg > round2.bufsize) {
                pthread_mutex_unlock(&round2.mutex);
                printf("Max %u messages exceeded\n", round2.bufsize);
                return;
            }
            round2.reserved += num_msgs_per_stg;
            pthread_mutex_unlock(&round2.mutex);
            myself_buf = round2.buf + start * msg_size;
        }
    }

    while (tot_msgs) {
        nodenum_t storage_node_id =
            nodenum_t((*(const uint32_t *)buf)>>DEST_UID_BITS);
        if (storage_node_id < num_storage_nodes) {
            nodenum_t node = g_teems_config.storage_map[storage_node_id];
            if (node == my_node_num) {
                memmove(myself_buf, buf, msg_size);
                myself_buf += msg_size;
            } else {
                g_commstates[node].message_data(buf, msg_size);
            }
        }

        buf += msg_size;
        --tot_msgs;
    }

    if (myself_buf) {
        MsgBuffer &round2 = route_state.round2;
        pthread_mutex_lock(&round2.mutex);
        round2.inserted += num_msgs_per_stg;
        round2.nodes_received += 1;
        pthread_mutex_unlock(&round2.mutex);
    }
}

// Perform the next round of routing.  The callback pointer will be
// passed to ocall_routing_round_complete when the round is complete.
void ecall_routing_proceed(void *cbpointer)
{
    uint8_t my_roles = g_teems_config.roles[g_teems_config.my_node_num];

    if (route_state.step == ROUTE_NOT_STARTED) {
        if (my_roles & ROLE_INGESTION) {
            route_state.cbpointer = cbpointer;
            MsgBuffer &ingbuf = route_state.ingbuf;

            pthread_mutex_lock(&ingbuf.mutex);
            // Ensure there are no pending messages currently being inserted
            // into the buffer
            while (ingbuf.reserved != ingbuf.inserted) {
                pthread_mutex_unlock(&ingbuf.mutex);
                pthread_mutex_lock(&ingbuf.mutex);
            }
            // Sort the messages we've received
#ifdef PROFILE_ROUTING
            uint32_t inserted = ingbuf.inserted;
            unsigned long start_round1 = printf_with_rtclock("begin round1 processing (%u)\n", inserted);
            unsigned long start_sort = printf_with_rtclock("begin oblivious sort (%u,%u)\n", inserted, route_state.tot_msg_per_ing);
#endif
            sort_mtobliv<UidKey>(g_teems_config.nthreads, ingbuf.buf,
                g_teems_config.msg_size, ingbuf.inserted,
                route_state.tot_msg_per_ing, send_round1_msgs);
#ifdef PROFILE_ROUTING
            printf_with_rtclock_diff(start_sort, "end oblivious sort (%u,%u)\n", inserted, route_state.tot_msg_per_ing);
            printf_with_rtclock_diff(start_round1, "end round1 processing (%u)\n", inserted);
#endif
            ingbuf.reset();
            pthread_mutex_unlock(&ingbuf.mutex);
        }
        if (my_roles & ROLE_ROUTING) {
            MsgBuffer &round1 = route_state.round1;

            pthread_mutex_lock(&round1.mutex);
            round1.completed_prev_round = true;
            nodenum_t nodes_received = round1.nodes_received;
            pthread_mutex_unlock(&round1.mutex);

            if (nodes_received == g_teems_config.num_ingestion_nodes) {
                route_state.step = ROUTE_ROUND_1;
                route_state.cbpointer = NULL;
                ocall_routing_round_complete(cbpointer, 1);
            }
        } else {
            route_state.step = ROUTE_ROUND_1;
            route_state.round1.completed_prev_round = true;
            ocall_routing_round_complete(cbpointer, 1);
        }
    } else if (route_state.step == ROUTE_ROUND_1) {
        if (my_roles & ROLE_ROUTING) {
            route_state.cbpointer = cbpointer;
            MsgBuffer &round1 = route_state.round1;

            pthread_mutex_lock(&round1.mutex);
            // Ensure there are no pending messages currently being inserted
            // into the buffer
            while (round1.reserved != round1.inserted) {
                pthread_mutex_unlock(&round1.mutex);
                pthread_mutex_lock(&round1.mutex);
            }

            // If the _total_ number of messages we received in round 1
            // is less than the max number of messages we could send to
            // _each_ storage node, then cap the number of messages we
            // will send to each storage node to that number.
            uint32_t msgs_per_stg = route_state.max_msg_to_each_stg;
            if (round1.inserted < msgs_per_stg) {
                msgs_per_stg = round1.inserted;
            }

            // Note: at this point, it is required that each message in
            // the round1 buffer have a _valid_ storage node id field.

            // Obliviously tally the number of messages we received in
            // round1 destined for each storage node
#ifdef PROFILE_ROUTING
            uint32_t inserted = round1.inserted;
            unsigned long start_round2 = printf_with_rtclock("begin round2 processing (%u,%u)\n", inserted, round1.bufsize);
            unsigned long start_tally = printf_with_rtclock("begin tally (%u)\n", inserted);
#endif
            uint16_t msg_size = g_teems_config.msg_size;
            nodenum_t num_storage_nodes = g_teems_config.num_storage_nodes;
            std::vector<uint32_t> tally = obliv_tally_stg(
                round1.buf, msg_size, round1.inserted, num_storage_nodes);
#ifdef PROFILE_ROUTING
            printf_with_rtclock_diff(start_tally, "end tally (%u)\n", inserted);
#endif

            // Note: tally contains private values!  It's OK to
            // non-obliviously check for an error condition, though.
            // While we're at it, obliviously change the tally of
            // messages received to a tally of padding messages
            // required.
            uint32_t tot_padding = 0;
            for (nodenum_t i=0; i<num_storage_nodes; ++i) {
                if (tally[i] > msgs_per_stg) {
                    printf("Received too many messages for storage node %u\n", i);
                    assert(tally[i] <= msgs_per_stg);
                }
                tally[i] = msgs_per_stg - tally[i];
                tot_padding += tally[i];
            }

            round1.reserved += tot_padding;
            assert(round1.reserved <= round1.bufsize);

            // Obliviously add padding for each storage node according
            // to the (private) padding tally.
#ifdef PROFILE_ROUTING
            unsigned long start_pad = printf_with_rtclock("begin pad (%u)\n", tot_padding);
#endif
            obliv_pad_stg(round1.buf + round1.inserted * msg_size,
                msg_size, tally, tot_padding);
#ifdef PROFILE_ROUTING
            printf_with_rtclock_diff(start_pad, "end pad (%u)\n", tot_padding);
#endif

            round1.inserted += tot_padding;

            // Obliviously shuffle the messages
#ifdef PROFILE_ROUTING
            unsigned long start_shuffle = printf_with_rtclock("begin shuffle (%u,%u)\n", round1.inserted, round1.bufsize);
#endif
            uint32_t num_shuffled = shuffle_mtobliv(g_teems_config.nthreads,
                round1.buf, msg_size, round1.inserted, round1.bufsize);
#ifdef PROFILE_ROUTING
            printf_with_rtclock_diff(start_shuffle, "end shuffle (%u,%u)\n", round1.inserted, round1.bufsize);
            printf_with_rtclock_diff(start_round2, "end round2 processing (%u,%u)\n", inserted, round1.bufsize);
#endif

            // Now we can handle the messages non-obliviously, since we
            // know there will be exactly msgs_per_stg messages to each
            // storage node, and the oblivious shuffle broke the
            // connection between where each message came from and where
            // it's going.
            send_round2_msgs(num_shuffled, msgs_per_stg);

            round1.reset();
            pthread_mutex_unlock(&round1.mutex);

        }
        if (my_roles & ROLE_STORAGE) {
            route_state.cbpointer = cbpointer;
            MsgBuffer &round2 = route_state.round2;

            pthread_mutex_lock(&round2.mutex);
            round2.completed_prev_round = true;
            nodenum_t nodes_received = round2.nodes_received;
            pthread_mutex_unlock(&round2.mutex);

            if (nodes_received == g_teems_config.num_routing_nodes) {
                route_state.step = ROUTE_ROUND_2;
                route_state.cbpointer = NULL;
                ocall_routing_round_complete(cbpointer, 2);
            }
        } else {
            route_state.step = ROUTE_ROUND_2;
            route_state.round2.completed_prev_round = true;
            ocall_routing_round_complete(cbpointer, 2);
        }
    } else if (route_state.step == ROUTE_ROUND_2) {
        if (my_roles & ROLE_STORAGE) {
            MsgBuffer &round2 = route_state.round2;

            pthread_mutex_lock(&round2.mutex);
            // Ensure there are no pending messages currently being inserted
            // into the buffer
            while (round2.reserved != round2.inserted) {
                pthread_mutex_unlock(&round2.mutex);
                pthread_mutex_lock(&round2.mutex);
            }

#ifdef PROFILE_ROUTING
            unsigned long start = printf_with_rtclock("begin storage processing (%u)\n", round2.inserted);
#endif
            storage_received(round2);
#ifdef PROFILE_ROUTING
            printf_with_rtclock_diff(start, "end storage processing (%u)\n", round2.inserted);
#endif

            // We're done
            route_state.step = ROUTE_NOT_STARTED;
            ocall_routing_round_complete(cbpointer, 0);
        } else {
            // We're done
            route_state.step = ROUTE_NOT_STARTED;
            ocall_routing_round_complete(cbpointer, 0);
        }
    }
}