#include "uplink.h"
#include "helper.h"
#include "locks.h"
#include "image.h"
#include "altservers.h"
#include "../shared/sockhelper.h"
#include "../shared/protocol.h"
#include "../shared/timing.h"
#include "../shared/crc32.h"
#include <assert.h>
#include <inttypes.h>
#include <fcntl.h>
#include <poll.h>
#include <unistd.h>
#include <stdatomic.h>
#define FILE_BYTES_PER_MAP_BYTE ( DNBD3_BLOCK_SIZE * 8 )
#define MAP_BYTES_PER_HASH_BLOCK (int)( HASH_BLOCK_SIZE / FILE_BYTES_PER_MAP_BYTE )
#define MAP_INDEX_HASH_START_MASK ( ~(int)( MAP_BYTES_PER_HASH_BLOCK - 1 ) )
#define REP_NONE ( (uint64_t)0xffffffffffffffff )
static atomic_uint_fast64_t totalBytesReceived = 0;
static void* uplink_mainloop(void *data);
static void uplink_sendRequests(dnbd3_connection_t *link, bool newOnly);
static int uplink_findNextIncompleteHashBlock(dnbd3_connection_t *link, const int lastBlockIndex);
static void uplink_handleReceive(dnbd3_connection_t *link);
static int uplink_sendKeepalive(const int fd);
static void uplink_addCrc32(dnbd3_connection_t *uplink);
static void uplink_sendReplicationRequest(dnbd3_connection_t *link);
static bool uplink_reopenCacheFd(dnbd3_connection_t *link, const bool force);
static bool uplink_saveCacheMap(dnbd3_connection_t *link);
static bool uplink_connectionShouldShutdown(dnbd3_connection_t *link);
static void uplink_connectionFailed(dnbd3_connection_t *link, bool findNew);
// ############ uplink connection handling
void uplink_globalsInit()
{
}
uint64_t uplink_getTotalBytesReceived()
{
return (uint64_t)totalBytesReceived;
}
/**
* Create and initialize an uplink instance for the given
* image. Uplinks run in their own thread.
* Locks on: _images[].lock
*/
bool uplink_init(dnbd3_image_t *image, int sock, dnbd3_host_t *host, int version)
{
if ( !_isProxy || _shutdown ) return false;
dnbd3_connection_t *link = NULL;
assert( image != NULL );
spin_lock( &image->lock );
if ( image->uplink != NULL && !image->uplink->shutdown ) {
spin_unlock( &image->lock );
if ( sock >= 0 ) close( sock );
return true; // There's already an uplink, so should we consider this success or failure?
}
if ( image->cache_map == NULL ) {
logadd( LOG_WARNING, "Uplink was requested for image %s, but it is already complete", image->name );
goto failure;
}
link = image->uplink = calloc( 1, sizeof(dnbd3_connection_t) );
spin_init( &link->queueLock, PTHREAD_PROCESS_PRIVATE );
spin_init( &link->rttLock, PTHREAD_PROCESS_PRIVATE );
link->image = image;
link->bytesReceived = 0;
link->idleTime = 0;
link->queueLen = 0;
link->fd = -1;
link->cacheFd = -1;
link->signal = NULL;
link->replicationHandle = REP_NONE;
spin_lock( &link->rttLock );
link->cycleDetected = false;
if ( sock >= 0 ) {
link->betterFd = sock;
link->betterServer = *host;
link->rttTestResult = RTT_DOCHANGE;
link->betterVersion = version;
} else {
link->betterFd = -1;
link->rttTestResult = RTT_IDLE;
}
spin_unlock( &link->rttLock );
link->recvBufferLen = 0;
link->shutdown = false;
if ( 0 != thread_create( &(link->thread), NULL, &uplink_mainloop, (void *)link ) ) {
logadd( LOG_ERROR, "Could not start thread for new uplink." );
goto failure;
}
spin_unlock( &image->lock );
return true;
failure: ;
if ( link != NULL ) {
free( link );
link = image->uplink = NULL;
}
spin_unlock( &image->lock );
return false;
}
/**
* Locks on image.lock, uplink.lock
* Calling it multiple times, even concurrently, will
* not break anything.
*/
void uplink_shutdown(dnbd3_image_t *image)
{
bool join = false;
pthread_t thread;
assert( image != NULL );
spin_lock( &image->lock );
if ( image->uplink == NULL ) {
spin_unlock( &image->lock );
return;
}
dnbd3_connection_t * const uplink = image->uplink;
spin_lock( &uplink->queueLock );
if ( !uplink->shutdown ) {
uplink->shutdown = true;
signal_call( uplink->signal );
thread = uplink->thread;
join = true;
}
spin_unlock( &uplink->queueLock );
bool wait = image->uplink != NULL;
spin_unlock( &image->lock );
if ( join ) thread_join( thread, NULL );
while ( wait ) {
usleep( 5000 );
spin_lock( &image->lock );
wait = image->uplink != NULL && image->uplink->shutdown;
spin_unlock( &image->lock );
}
}
/**
* Remove given client from uplink request queue
* Locks on: uplink.queueLock
*/
void uplink_removeClient(dnbd3_connection_t *uplink, dnbd3_client_t *client)
{
spin_lock( &uplink->queueLock );
for (int i = uplink->queueLen - 1; i >= 0; --i) {
if ( uplink->queue[i].client == client ) {
uplink->queue[i].client = NULL;
uplink->queue[i].status = ULR_FREE;
}
if ( uplink->queue[i].client == NULL && uplink->queueLen == i + 1 ) uplink->queueLen--;
}
spin_unlock( &uplink->queueLock );
}
/**
* Request a chunk of data through an uplink server
* Locks on: image.lock, uplink.queueLock
*/
bool uplink_request(dnbd3_client_t *client, uint64_t handle, uint64_t start, uint32_t length, uint8_t hops)
{
if ( client == NULL || client->image == NULL ) return false;
if ( length > (uint32_t)_maxPayload ) {
logadd( LOG_WARNING, "Cannot relay request by client; length of %" PRIu32 " exceeds maximum payload", length );
return false;
}
spin_lock( &client->image->lock );
if ( client->image->uplink == NULL ) {
spin_unlock( &client->image->lock );
logadd( LOG_DEBUG1, "Uplink request for image with no uplink" );
return false;
}
dnbd3_connection_t * const uplink = client->image->uplink;
if ( uplink->shutdown ) {
spin_unlock( &client->image->lock );
logadd( LOG_DEBUG1, "Uplink request for image with uplink shutting down" );
return false;
}
// Check if the client is the same host as the uplink. If so assume this is a circular proxy chain
// This might be a false positive if there are multiple instances running on the same host (IP)
if ( hops != 0 && isSameAddress( &uplink->currentServer, &client->host ) ) {
spin_unlock( &client->image->lock );
logadd( LOG_WARNING, "Proxy cycle detected (same host)." );
spin_lock( &uplink->rttLock );
uplink->cycleDetected = true;
spin_unlock( &uplink->rttLock );
signal_call( uplink->signal );
return false;
}
int foundExisting = -1; // Index of a pending request that is a superset of our range, -1 otherwise
int existingType = -1; // ULR_* type of existing request
int i;
int freeSlot = -1;
bool requestLoop = false;
const uint64_t end = start + length;
spin_lock( &uplink->queueLock );
spin_unlock( &client->image->lock );
for (i = 0; i < uplink->queueLen; ++i) {
if ( freeSlot == -1 && uplink->queue[i].status == ULR_FREE ) {
freeSlot = i;
continue;
}
if ( uplink->queue[i].status != ULR_PENDING && uplink->queue[i].status != ULR_NEW ) continue;
if ( uplink->queue[i].from <= start && uplink->queue[i].to >= end ) {
if ( hops > uplink->queue[i].hopCount && uplink->queue[i].from == start && uplink->queue[i].to == end ) {
requestLoop = true;
break;
}
if ( foundExisting == -1 || existingType == ULR_PENDING ) {
foundExisting = i;
existingType = uplink->queue[i].status;
if ( freeSlot != -1 ) break;
}
}
}
if ( requestLoop ) {
spin_unlock( &uplink->queueLock );
logadd( LOG_WARNING, "Rejecting relay of request to upstream proxy because of possible cyclic proxy chain. Incoming hop-count is %" PRIu8 ".", hops );
spin_lock( &uplink->rttLock );
uplink->cycleDetected = true;
spin_unlock( &uplink->rttLock );
signal_call( uplink->signal );
return false;
}
if ( freeSlot == -1 ) {
if ( uplink->queueLen >= SERVER_MAX_UPLINK_QUEUE ) {
spin_unlock( &uplink->queueLock );
logadd( LOG_WARNING, "Uplink queue is full, consider increasing SERVER_MAX_UPLINK_QUEUE. Dropping client..." );
return false;
}
freeSlot = uplink->queueLen++;
}
// Do not send request to uplink server if we have a matching pending request AND the request either has the
// status ULR_NEW OR we found a free slot with LOWER index than the one we attach to. Otherwise
// explicitly send this request to the uplink server. The second condition mentioned here is to prevent
// a race condition where the reply for the outstanding request already arrived and the uplink thread
// is currently traversing the request queue. As it is processing the queue from highest to lowest index, it might
// already have passed the index of the free slot we determined, but not reached the existing request we just found above.
if ( foundExisting != -1 && existingType != ULR_NEW && freeSlot > foundExisting ) foundExisting = -1; // -1 means "send request"
#ifdef _DEBUG
if ( foundExisting != -1 ) {
logadd( LOG_DEBUG2, "%p (%s) Found existing request of type %s at slot %d, attaching in slot %d.\n", (void*)uplink, uplink->image->name, existingType == ULR_NEW ? "ULR_NEW" : "ULR_PENDING", foundExisting, freeSlot );
logadd( LOG_DEBUG2, "Original %" PRIu64 "-%" PRIu64 " (%p)\n"
"New %" PRIu64 "-%" PRIu64 " (%p)\n",
uplink->queue[foundExisting].from, uplink->queue[foundExisting].to, (void*)uplink->queue[foundExisting].client,
start, end, (void*)client );
}
#endif
// Fill structure
uplink->queue[freeSlot].from = start;
uplink->queue[freeSlot].to = end;
uplink->queue[freeSlot].handle = handle;
uplink->queue[freeSlot].client = client;
//int old = uplink->queue[freeSlot].status;
uplink->queue[freeSlot].status = (foundExisting == -1 ? ULR_NEW : ULR_PENDING);
uplink->queue[freeSlot].hopCount = hops;
#ifdef _DEBUG
timing_get( &uplink->queue[freeSlot].entered );
//logadd( LOG_DEBUG2 %p] Inserting request at slot %d, was %d, now %d, handle %" PRIu64 ", Range: %" PRIu64 "-%" PRIu64 "\n", (void*)uplink, freeSlot, old, uplink->queue[freeSlot].status, uplink->queue[freeSlot, ".handle, start, end );
#endif
spin_unlock( &uplink->queueLock );
if ( foundExisting == -1 ) { // Only wake up uplink thread if the request needs to be relayed
if ( signal_call( uplink->signal ) == SIGNAL_ERROR ) {
logadd( LOG_WARNING, "Cannot wake up uplink thread; errno=%d", (int)errno );
}
}
return true;
}
/**
* Uplink thread.
* Locks are irrelevant as this is never called from another function
*/
static void* uplink_mainloop(void *data)
{
#define EV_SIGNAL (0)
#define EV_SOCKET (1)
#define EV_COUNT (2)
struct pollfd events[EV_COUNT];
dnbd3_connection_t * const link = (dnbd3_connection_t*)data;
int numSocks, i, waitTime;
int altCheckInterval = SERVER_RTT_INTERVAL_INIT;
uint32_t discoverFailCount = 0;
uint32_t unsavedSeconds = 0;
ticks nextAltCheck, lastKeepalive;
char buffer[200];
memset( events, 0, sizeof(events) );
timing_get( &nextAltCheck );
lastKeepalive = nextAltCheck;
//
assert( link != NULL );
setThreadName( "idle-uplink" );
blockNoncriticalSignals();
// Make sure file is open for writing
if ( !uplink_reopenCacheFd( link, false ) ) {
// It might have failed - still offer proxy mode, we just can't cache
logadd( LOG_WARNING, "Cannot open cache file %s for writing (errno=%d); will just proxy traffic without caching!", link->image->path, errno );
}
//
link->signal = signal_new();
if ( link->signal == NULL ) {
logadd( LOG_WARNING, "error creating signal. Uplink unavailable." );
goto cleanup;
}
events[EV_SIGNAL].events = POLLIN;
events[EV_SIGNAL].fd = signal_getWaitFd( link->signal );
events[EV_SOCKET].fd = -1;
while ( !_shutdown && !link->shutdown ) {
// poll()
spin_lock( &link->rttLock );
waitTime = link->rttTestResult == RTT_DOCHANGE ? 0 : -1;
spin_unlock( &link->rttLock );
if ( waitTime == 0 ) {
// Nothing
} else if ( link->fd == -1 && !uplink_connectionShouldShutdown( link ) ) {
waitTime = 1000;
} else {
declare_now;
waitTime = (int)timing_diffMs( &now, &nextAltCheck );
if ( waitTime < 100 ) waitTime = 100;
if ( waitTime > 5000 ) waitTime = 5000;
}
events[EV_SOCKET].fd = link->fd;
numSocks = poll( events, EV_COUNT, waitTime );
if ( _shutdown || link->shutdown ) goto cleanup;
if ( numSocks == -1 ) { // Error?
if ( errno == EINTR ) continue;
logadd( LOG_DEBUG1, "poll() error %d", (int)errno );
usleep( 10000 );
continue;
}
// Check if server switch is in order
spin_lock( &link->rttLock );
if ( link->rttTestResult != RTT_DOCHANGE ) {
spin_unlock( &link->rttLock );
} else {
link->rttTestResult = RTT_IDLE;
// The rttTest worker thread has finished our request.
// And says it's better to switch to another server
const int fd = link->fd;
link->fd = link->betterFd;
link->betterFd = -1;
link->currentServer = link->betterServer;
link->version = link->betterVersion;
link->cycleDetected = false;
spin_unlock( &link->rttLock );
discoverFailCount = 0;
if ( fd != -1 ) close( fd );
link->replicationHandle = REP_NONE;
link->image->working = true;
link->replicatedLastBlock = false; // Reset this to be safe - request could've been sent but reply was never received
buffer[0] = '@';
if ( host_to_string( &link->currentServer, buffer + 1, sizeof(buffer) - 1 ) ) {
logadd( LOG_DEBUG1, "(Uplink %s) Now connected to %s\n", link->image->name, buffer + 1 );
setThreadName( buffer );
}
// If we don't have a crc32 list yet, see if the new server has one
if ( link->image->crc32 == NULL ) {
uplink_addCrc32( link );
}
// Re-send all pending requests
uplink_sendRequests( link, false );
uplink_sendReplicationRequest( link );
events[EV_SOCKET].events = POLLIN | POLLRDHUP;
timing_gets( &nextAltCheck, altCheckInterval );
// The rtt worker already did the handshake for our image, so there's nothing
// more to do here
}
// Check events
// Signal
if ( (events[EV_SIGNAL].revents & (POLLERR | POLLHUP | POLLRDHUP | POLLNVAL)) ) {
logadd( LOG_WARNING, "poll error on signal in uplink_mainloop!" );
goto cleanup;
} else if ( (events[EV_SIGNAL].revents & POLLIN) ) {
// signal triggered -> pending requests
if ( signal_clear( link->signal ) == SIGNAL_ERROR ) {
logadd( LOG_WARNING, "Errno on signal on uplink for %s! Things will break!", link->image->name );
}
if ( link->fd != -1 ) {
// Uplink seems fine, relay requests to it...
uplink_sendRequests( link, true );
} else { // No uplink; maybe it was shutdown since it was idle for too long
link->idleTime = 0;
}
}
// Uplink socket
if ( (events[EV_SOCKET].revents & (POLLERR | POLLHUP | POLLRDHUP | POLLNVAL)) ) {
uplink_connectionFailed( link, true );
logadd( LOG_DEBUG1, "Uplink gone away, panic!\n" );
setThreadName( "panic-uplink" );
} else if ( (events[EV_SOCKET].revents & POLLIN) ) {
uplink_handleReceive( link );
if ( _shutdown || link->shutdown ) goto cleanup;
}
declare_now;
uint32_t timepassed = timing_diff( &lastKeepalive, &now );
if ( timepassed >= SERVER_UPLINK_KEEPALIVE_INTERVAL ) {
lastKeepalive = now;
link->idleTime += timepassed;
unsavedSeconds += timepassed;
if ( unsavedSeconds > 240 || ( unsavedSeconds > 60 && link->idleTime >= 20 && link->idleTime <= 70 ) ) {
// fsync/save every 4 minutes, or every 60 seconds if link is idle
unsavedSeconds = 0;
uplink_saveCacheMap( link );
}
// Keep-alive
if ( link->fd != -1 && link->replicationHandle == REP_NONE ) {
// Send keep-alive if nothing is happening
if ( uplink_sendKeepalive( link->fd ) ) {
// Re-trigger periodically, in case it requires a minimum user count
uplink_sendReplicationRequest( link );
} else {
uplink_connectionFailed( link, true );
logadd( LOG_DEBUG1, "Error sending keep-alive, panic!\n" );
setThreadName( "panic-uplink" );
}
}
// Don't keep link established if we're idle for too much
if ( link->fd != -1 && uplink_connectionShouldShutdown( link ) ) {
close( link->fd );
link->fd = events[EV_SOCKET].fd = -1;
link->cycleDetected = false;
if ( link->recvBufferLen != 0 ) {
link->recvBufferLen = 0;
free( link->recvBuffer );
link->recvBuffer = NULL;
}
logadd( LOG_DEBUG1, "Closing idle uplink for image %s:%d", link->image->name, (int)link->image->rid );
setThreadName( "idle-uplink" );
}
}
// See if we should trigger an RTT measurement
spin_lock( &link->rttLock );
const int rttTestResult = link->rttTestResult;
spin_unlock( &link->rttLock );
if ( rttTestResult == RTT_IDLE || rttTestResult == RTT_DONTCHANGE ) {
if ( timing_reached( &nextAltCheck, &now ) || ( link->fd == -1 && !uplink_connectionShouldShutdown( link ) ) || link->cycleDetected ) {
// It seems it's time for a check
if ( image_isComplete( link->image ) ) {
// Quit work if image is complete
logadd( LOG_INFO, "Replication of %s complete.", link->image->name );
setThreadName( "finished-uplink" );
goto cleanup;
} else if ( !uplink_connectionShouldShutdown( link ) ) {
// Not complete - do measurement
altservers_findUplink( link ); // This will set RTT_INPROGRESS (synchronous)
if ( _backgroundReplication == BGR_FULL && link->nextReplicationIndex == -1 ) {
link->nextReplicationIndex = 0;
}
}
altCheckInterval = MIN(altCheckInterval + 1, SERVER_RTT_INTERVAL_MAX);
timing_set( &nextAltCheck, &now, altCheckInterval );
}
} else if ( rttTestResult == RTT_NOT_REACHABLE ) {
spin_lock( &link->rttLock );
link->rttTestResult = RTT_IDLE;
spin_unlock( &link->rttLock );
discoverFailCount++;
timing_set( &nextAltCheck, &now, (discoverFailCount < SERVER_RTT_BACKOFF_COUNT ? altCheckInterval : SERVER_RTT_INTERVAL_FAILED) );
}
#ifdef _DEBUG
if ( link->fd != -1 && !link->shutdown ) {
bool resend = false;
ticks deadline;
timing_set( &deadline, &now, -10 );
spin_lock( &link->queueLock );
for (i = 0; i < link->queueLen; ++i) {
if ( link->queue[i].status != ULR_FREE && timing_reached( &link->queue[i].entered, &deadline ) ) {
snprintf( buffer, sizeof(buffer), "[DEBUG %p] Starving request slot %d detected:\n"
"%s\n(from %" PRIu64 " to %" PRIu64 ", status: %d)\n", (void*)link, i, link->queue[i].client->image->name,
link->queue[i].from, link->queue[i].to, link->queue[i].status );
link->queue[i].entered = now;
#ifdef _DEBUG_RESEND_STARVING
link->queue[i].status = ULR_NEW;
resend = true;
#endif
spin_unlock( &link->queueLock );
logadd( LOG_WARNING, "%s", buffer );
spin_lock( &link->queueLock );
}
}
spin_unlock( &link->queueLock );
if ( resend )
uplink_sendRequests( link, true );
}
#endif
}
cleanup: ;
altservers_removeUplink( link );
uplink_saveCacheMap( link );
spin_lock( &link->image->lock );
if ( link->image->uplink == link ) {
link->image->uplink = NULL;
}
spin_lock( &link->queueLock );
const int fd = link->fd;
const dnbd3_signal_t* signal = link->signal;
link->fd = -1;
link->signal = NULL;
if ( !link->shutdown ) {
link->shutdown = true;
thread_detach( link->thread );
}
// Do not access link->image after unlocking, since we set
// image->uplink to NULL. Acquire with image_lock first,
// like done below when checking whether to re-init uplink
spin_unlock( &link->image->lock );
spin_unlock( &link->queueLock );
if ( fd != -1 ) close( fd );
if ( signal != NULL ) signal_close( signal );
// Wait for the RTT check to finish/fail if it's in progress
while ( link->rttTestResult == RTT_INPROGRESS )
usleep( 10000 );
if ( link->betterFd != -1 ) {
close( link->betterFd );
}
spin_destroy( &link->queueLock );
spin_destroy( &link->rttLock );
free( link->recvBuffer );
link->recvBuffer = NULL;
if ( link->cacheFd != -1 ) {
close( link->cacheFd );
}
dnbd3_image_t *image = image_lock( link->image );
free( link ); // !!!
if ( image != NULL ) {
if ( !_shutdown && image->cache_map != NULL ) {
// Ingegrity checker must have found something in the meantime
uplink_init( image, -1, NULL, 0 );
}
image_release( image );
}
return NULL ;
}
static void uplink_sendRequests(dnbd3_connection_t *link, bool newOnly)
{
// Scan for new requests
int j;
spin_lock( &link->queueLock );
for (j = 0; j < link->queueLen; ++j) {
if ( link->queue[j].status != ULR_NEW && (newOnly || link->queue[j].status != ULR_PENDING) ) continue;
link->queue[j].status = ULR_PENDING;
uint8_t hops = link->queue[j].hopCount;
const uint64_t reqStart = link->queue[j].from & ~(uint64_t)(DNBD3_BLOCK_SIZE - 1);
const uint32_t reqSize = (uint32_t)(((link->queue[j].to + DNBD3_BLOCK_SIZE - 1) & ~(uint64_t)(DNBD3_BLOCK_SIZE - 1)) - reqStart);
/*
logadd( LOG_DEBUG2, "[%p] Sending slot %d, now %d, handle %" PRIu64 ", Range: %" PRIu64 "-%" PRIu64 " (%" PRIu64 "-%" PRIu64 ")",
(void*)link, j, link->queue[j].status, link->queue[j].handle, link->queue[j].from, link->queue[j].to, reqStart, reqStart+reqSize );
*/
spin_unlock( &link->queueLock );
if ( hops < 200 ) ++hops;
const int ret = dnbd3_get_block( link->fd, reqStart, reqSize, reqStart, COND_HOPCOUNT( link->version, hops ) );
if ( !ret ) {
// Non-critical - if the connection dropped or the server was changed
// the thread will re-send this request as soon as the connection
// is reestablished.
logadd( LOG_DEBUG1, "Error forwarding request to uplink server!\n" );
altservers_serverFailed( &link->currentServer );
return;
}
spin_lock( &link->queueLock );
}
spin_unlock( &link->queueLock );
}
/**
* Send a block request to an uplink server without really having
* any client that needs that data. This will be used for background replication.
*
* We'll go through the cache map of the image and look for bytes that don't have
* all bits set. We then request the corresponding 8 blocks of 4kb from the uplink
* server. This means we might request data we already have, but it makes
* the code simpler. Worst case would be only one bit is zero, which means
* 4kb are missing, but we will request 32kb.
*/
static void uplink_sendReplicationRequest(dnbd3_connection_t *link)
{
if ( link == NULL || link->fd == -1 ) return;
if ( _backgroundReplication == BGR_DISABLED || link->cacheFd == -1 ) return; // Don't do background replication
if ( link->nextReplicationIndex == -1 || link->replicationHandle != REP_NONE )
return;
dnbd3_image_t * const image = link->image;
if ( image->virtualFilesize < DNBD3_BLOCK_SIZE ) return;
spin_lock( &image->lock );
if ( image == NULL || image->cache_map == NULL || image->users < _bgrMinClients ) {
// No cache map (=image complete), or replication pending, or not enough users, do nothing
spin_unlock( &image->lock );
return;
}
const int mapBytes = IMGSIZE_TO_MAPBYTES( image->virtualFilesize );
const int lastBlockIndex = mapBytes - 1;
int endByte;
if ( _backgroundReplication == BGR_FULL ) { // Full mode: consider all blocks
endByte = link->nextReplicationIndex + mapBytes;
} else { // Hashblock based: Only look for match in current hash block
endByte = ( link->nextReplicationIndex + MAP_BYTES_PER_HASH_BLOCK ) & MAP_INDEX_HASH_START_MASK;
if ( endByte > mapBytes ) {
endByte = mapBytes;
}
}
int replicationIndex = -1;
for ( int j = link->nextReplicationIndex; j < endByte; ++j ) {
const int i = j % ( mapBytes ); // Wrap around for BGR_FULL
if ( image->cache_map[i] != 0xff && ( i != lastBlockIndex || !link->replicatedLastBlock ) ) {
// Found incomplete one
replicationIndex = i;
break;
}
}
spin_unlock( &image->lock );
if ( replicationIndex == -1 && _backgroundReplication == BGR_HASHBLOCK ) {
// Nothing left in current block, find next one
replicationIndex = uplink_findNextIncompleteHashBlock( link, endByte );
}
if ( replicationIndex == -1 ) {
// Replication might be complete, uplink_mainloop should take care....
link->nextReplicationIndex = -1;
return;
}
const uint64_t offset = (uint64_t)replicationIndex * FILE_BYTES_PER_MAP_BYTE;
link->replicationHandle = offset;
const uint32_t size = (uint32_t)MIN( image->virtualFilesize - offset, FILE_BYTES_PER_MAP_BYTE );
if ( !dnbd3_get_block( link->fd, offset, size, link->replicationHandle, COND_HOPCOUNT( link->version, 1 ) ) ) {
logadd( LOG_DEBUG1, "Error sending background replication request to uplink server!\n" );
return;
}
if ( replicationIndex == lastBlockIndex ) {
link->replicatedLastBlock = true; // Special treatment, last byte in map could represent less than 8 blocks
}
link->nextReplicationIndex = replicationIndex + 1; // Remember last incomplete offset for next time so we don't play Schlemiel the painter
if ( _backgroundReplication == BGR_HASHBLOCK
&& link->nextReplicationIndex % MAP_BYTES_PER_HASH_BLOCK == 0 ) {
// Just crossed a hash block boundary, look for new candidate starting at this very index
link->nextReplicationIndex = uplink_findNextIncompleteHashBlock( link, link->nextReplicationIndex );
}
}
/**
* find next index into cache_map that corresponds to the beginning
* of a hash block which is neither completely empty nor completely
* replicated yet. Returns -1 if no match.
*/
static int uplink_findNextIncompleteHashBlock(dnbd3_connection_t *link, const int startMapIndex)
{
int retval = -1;
spin_lock( &link->image->lock );
const int mapBytes = IMGSIZE_TO_MAPBYTES( link->image->virtualFilesize );
const uint8_t *cache_map = link->image->cache_map;
if ( cache_map != NULL ) {
int j;
const int start = ( startMapIndex & MAP_INDEX_HASH_START_MASK );
for (j = 0; j < mapBytes; ++j) {
const int i = ( start + j ) % mapBytes;
const bool isFull = cache_map[i] == 0xff || ( i + 1 == mapBytes && link->replicatedLastBlock );
const bool isEmpty = cache_map[i] == 0;
if ( !isEmpty && !isFull ) {
// Neither full nor empty, replicate
if ( retval == -1 ) {
retval = i;
}
break;
}
if ( ( i & MAP_INDEX_HASH_START_MASK ) == i ) {
// Reset state if we just crossed into the next hash chunk
retval = ( isEmpty ) ? ( i ) : ( -1 );
} else if ( isFull ) {
if ( retval != -1 ) {
// It's a full one, previous one was empty -> replicate
break;
}
} else if ( isEmpty ) {
if ( retval == -1 ) { // Previous one was full -> replicate
retval = i;
break;
}
}
}
if ( j == mapBytes ) { // Nothing found, loop ran until end
retval = -1;
}
}
spin_unlock( &link->image->lock );
return retval;
}
/**
* Receive data from uplink server and process/dispatch
* Locks on: link.lock, images[].lock
*/
static void uplink_handleReceive(dnbd3_connection_t *link)
{
dnbd3_reply_t inReply, outReply;
int ret, i;
for (;;) {
ret = dnbd3_read_reply( link->fd, &inReply, false );
if ( unlikely( ret == REPLY_INTR ) && likely( !_shutdown && !link->shutdown ) ) continue;
if ( ret == REPLY_AGAIN ) break;
if ( unlikely( ret == REPLY_CLOSED ) ) {
logadd( LOG_INFO, "Uplink: Remote host hung up (%s)", link->image->path );
goto error_cleanup;
}
if ( unlikely( ret == REPLY_WRONGMAGIC ) ) {
logadd( LOG_WARNING, "Uplink server's packet did not start with dnbd3_packet_magic (%s)", link->image->path );
goto error_cleanup;
}
if ( unlikely( ret != REPLY_OK ) ) {
logadd( LOG_INFO, "Uplink: Connection error %d (%s)", ret, link->image->path );
goto error_cleanup;
}
if ( unlikely( inReply.size > (uint32_t)_maxPayload ) ) {
logadd( LOG_WARNING, "Pure evil: Uplink server sent too much payload (%" PRIu32 ") for %s", inReply.size, link->image->path );
goto error_cleanup;
}
if ( unlikely( link->recvBufferLen < inReply.size ) ) {
link->recvBufferLen = MIN((uint32_t)_maxPayload, inReply.size + 65536);
link->recvBuffer = realloc( link->recvBuffer, link->recvBufferLen );
if ( link->recvBuffer == NULL ) {
logadd( LOG_ERROR, "Out of memory when trying to allocate receive buffer for uplink" );
exit( 1 );
}
}
if ( unlikely( (uint32_t)sock_recv( link->fd, link->recvBuffer, inReply.size ) != inReply.size ) ) {
logadd( LOG_INFO, "Lost connection to uplink server of %s (payload)", link->image->path );
goto error_cleanup;
}
// Payload read completely
// Bail out if we're not interested
if ( unlikely( inReply.cmd != CMD_GET_BLOCK ) ) continue;
// Is a legit block reply
struct iovec iov[2];
const uint64_t start = inReply.handle;
const uint64_t end = inReply.handle + inReply.size;
totalBytesReceived += inReply.size;
link->bytesReceived += inReply.size;
// 1) Write to cache file
if ( unlikely( link->cacheFd == -1 ) ) {
uplink_reopenCacheFd( link, false );
}
if ( likely( link->cacheFd != -1 ) ) {
int err = 0;
bool tryAgain = true; // Allow one retry in case we run out of space or the write fd became invalid
uint32_t done = 0;
ret = 0;
while ( done < inReply.size ) {
ret = (int)pwrite( link->cacheFd, link->recvBuffer + done, inReply.size - done, start + done );
if ( unlikely( ret == -1 ) ) {
err = errno;
if ( err == EINTR ) continue;
if ( err == ENOSPC || err == EDQUOT ) {
// try to free 256MiB
if ( !tryAgain || !image_ensureDiskSpaceLocked( 256ull * 1024 * 1024, true ) ) break;
tryAgain = false;
continue; // Success, retry write
}
if ( err == EBADF || err == EINVAL || err == EIO ) {
if ( !tryAgain || !uplink_reopenCacheFd( link, true ) )
break;
tryAgain = false;
continue; // Write handle to image successfully re-opened, try again
}
logadd( LOG_DEBUG1, "Error trying to cache data for %s:%d -- errno=%d", link->image->name, (int)link->image->rid, err );
break;
}
if ( unlikely( ret <= 0 || (uint32_t)ret > inReply.size - done ) ) {
logadd( LOG_WARNING, "Unexpected return value %d from pwrite to %s:%d", ret, link->image->name, (int)link->image->rid );
break;
}
done += (uint32_t)ret;
}
if ( likely( done > 0 ) ) {
image_updateCachemap( link->image, start, start + done, true );
}
if ( unlikely( ret == -1 && ( err == EBADF || err == EINVAL || err == EIO ) ) ) {
logadd( LOG_WARNING, "Error writing received data for %s:%d (errno=%d); disabling caching.",
link->image->name, (int)link->image->rid, err );
}
}
// 2) Figure out which clients are interested in it
spin_lock( &link->queueLock );
for (i = 0; i < link->queueLen; ++i) {
dnbd3_queued_request_t * const req = &link->queue[i];
assert( req->status != ULR_PROCESSING );
if ( req->status != ULR_PENDING && req->status != ULR_NEW ) continue;
assert( req->client != NULL );
if ( req->from >= start && req->to <= end ) { // Match :-)
req->status = ULR_PROCESSING;
}
}
// 3) Send to interested clients - iterate backwards so request collaboration works, and
// so we can decrease queueLen on the fly while iterating. Should you ever change this to start
// from 0, you also need to change the "attach to existing request"-logic in uplink_request()
outReply.magic = dnbd3_packet_magic;
bool served = false;
for ( i = link->queueLen - 1; i >= 0; --i ) {
dnbd3_queued_request_t * const req = &link->queue[i];
if ( req->status == ULR_PROCESSING ) {
size_t bytesSent = 0;
assert( req->from >= start && req->to <= end );
dnbd3_client_t * const client = req->client;
outReply.cmd = CMD_GET_BLOCK;
outReply.handle = req->handle;
outReply.size = (uint32_t)( req->to - req->from );
iov[0].iov_base = &outReply;
iov[0].iov_len = sizeof outReply;
iov[1].iov_base = link->recvBuffer + (req->from - start);
iov[1].iov_len = outReply.size;
fixup_reply( outReply );
req->status = ULR_FREE;
req->client = NULL;
served = true;
pthread_mutex_lock( &client->sendMutex );
spin_unlock( &link->queueLock );
if ( client->sock != -1 ) {
ssize_t sent = writev( client->sock, iov, 2 );
if ( sent > (ssize_t)sizeof outReply ) {
bytesSent = (size_t)sent - sizeof outReply;
}
}
pthread_mutex_unlock( &client->sendMutex );
if ( bytesSent != 0 ) {
client->bytesSent += bytesSent;
}
spin_lock( &link->queueLock );
}
if ( req->status == ULR_FREE && i == link->queueLen - 1 ) link->queueLen--;
}
spin_unlock( &link->queueLock );
#ifdef _DEBUG
if ( !served && start != link->replicationHandle ) {
logadd( LOG_DEBUG2, "%p, %s -- Unmatched reply: %" PRIu64 " to %" PRIu64, (void*)link, link->image->name, start, end );
}
#endif
if ( start == link->replicationHandle ) {
// Was our background replication
link->replicationHandle = REP_NONE;
// Try to remove from fs cache if no client was interested in this data
if ( !served && link->cacheFd != -1 ) {
posix_fadvise( link->cacheFd, start, inReply.size, POSIX_FADV_DONTNEED );
}
}
if ( served ) {
// Was some client -- reset idle counter
link->idleTime = 0;
// Re-enable replication if disabled
if ( link->nextReplicationIndex == -1 ) {
link->nextReplicationIndex = (int)( start / FILE_BYTES_PER_MAP_BYTE ) & MAP_INDEX_HASH_START_MASK;
}
}
}
if ( link->replicationHandle == REP_NONE ) {
spin_lock( &link->queueLock );
const bool rep = ( link->queueLen == 0 );
spin_unlock( &link->queueLock );
if ( rep ) uplink_sendReplicationRequest( link );
}
return;
// Error handling from failed receive or message parsing
error_cleanup: ;
uplink_connectionFailed( link, true );
}
static void uplink_connectionFailed(dnbd3_connection_t *link, bool findNew)
{
if ( link->fd == -1 )
return;
altservers_serverFailed( &link->currentServer );
close( link->fd );
link->fd = -1;
link->replicationHandle = REP_NONE;
if ( _backgroundReplication == BGR_FULL && link->nextReplicationIndex == -1 ) {
link->nextReplicationIndex = 0;
}
if ( !findNew )
return;
spin_lock( &link->rttLock );
bool bail = link->rttTestResult == RTT_INPROGRESS || link->betterFd != -1;
spin_unlock( &link->rttLock );
if ( bail )
return;
altservers_findUplink( link );
}
/**
* Send keep alive request to server
*/
static int uplink_sendKeepalive(const int fd)
{
static dnbd3_request_t request = { 0 };
if ( request.magic == 0 ) {
request.magic = dnbd3_packet_magic;
request.cmd = CMD_KEEPALIVE;
fixup_request( request );
}
return send( fd, &request, sizeof(request), MSG_NOSIGNAL ) == sizeof(request);
}
static void uplink_addCrc32(dnbd3_connection_t *uplink)
{
dnbd3_image_t *image = uplink->image;
if ( image == NULL || image->virtualFilesize == 0 ) return;
size_t bytes = IMGSIZE_TO_HASHBLOCKS( image->virtualFilesize ) * sizeof(uint32_t);
uint32_t masterCrc;
uint32_t *buffer = malloc( bytes );
if ( !dnbd3_get_crc32( uplink->fd, &masterCrc, buffer, &bytes ) || bytes == 0 ) {
free( buffer );
return;
}
uint32_t lists_crc = crc32( 0, NULL, 0 );
lists_crc = crc32( lists_crc, (uint8_t*)buffer, bytes );
lists_crc = net_order_32( lists_crc );
if ( lists_crc != masterCrc ) {
logadd( LOG_WARNING, "Received corrupted crc32 list from uplink server (%s)!", uplink->image->name );
free( buffer );
return;
}
uplink->image->masterCrc32 = masterCrc;
uplink->image->crc32 = buffer;
const size_t len = strlen( uplink->image->path ) + 30;
char path[len];
snprintf( path, len, "%s.crc", uplink->image->path );
const int fd = open( path, O_WRONLY | O_CREAT, 0644 );
if ( fd >= 0 ) {
write( fd, &masterCrc, sizeof(uint32_t) );
write( fd, buffer, bytes );
close( fd );
}
}
/**
* Open the given image's main image file in
* rw mode, assigning it to the cacheFd struct member.
*
* @param force If cacheFd was previously assigned a file descriptor (not == -1),
* it will be closed first. Otherwise, nothing will happen and true will be returned
* immediately.
*/
static bool uplink_reopenCacheFd(dnbd3_connection_t *link, const bool force)
{
if ( link->cacheFd != -1 ) {
if ( !force ) return true;
close( link->cacheFd );
}
link->cacheFd = open( link->image->path, O_WRONLY | O_CREAT, 0644 );
return link->cacheFd != -1;
}
/**
* Saves the cache map of the given image.
* Return true on success.
* Locks on: imageListLock, image.lock
*/
static bool uplink_saveCacheMap(dnbd3_connection_t *link)
{
dnbd3_image_t *image = link->image;
assert( image != NULL );
if ( link->cacheFd != -1 ) {
if ( fsync( link->cacheFd ) == -1 ) {
// A failing fsync means we have no guarantee that any data
// since the last fsync (or open if none) has been saved. Apart
// from keeping the cache_map from the last successful fsync
// around and restoring it there isn't much we can do to recover
// a consistent state. Bail out.
logadd( LOG_ERROR, "fsync() on image file %s failed with errno %d", image->path, errno );
logadd( LOG_ERROR, "Bailing out immediately" );
exit( 1 );
}
}
if ( image->cache_map == NULL ) return true;
logadd( LOG_DEBUG2, "Saving cache map of %s:%d", image->name, (int)image->rid );
spin_lock( &image->lock );
// Lock and get a copy of the cache map, as it could be freed by another thread that is just about to
// figure out that this image's cache copy is complete
if ( image->cache_map == NULL || image->virtualFilesize < DNBD3_BLOCK_SIZE ) {
spin_unlock( &image->lock );
return true;
}
const size_t size = IMGSIZE_TO_MAPBYTES(image->virtualFilesize);
uint8_t *map = malloc( size );
memcpy( map, image->cache_map, size );
// Unlock. Use path and cacheFd without locking. path should never change after initialization of the image,
// cacheFd is owned by the uplink thread and we don't want to hold a spinlock during I/O
spin_unlock( &image->lock );
assert( image->path != NULL );
char mapfile[strlen( image->path ) + 4 + 1];
strcpy( mapfile, image->path );
strcat( mapfile, ".map" );
int fd = open( mapfile, O_WRONLY | O_CREAT, 0644 );
if ( fd == -1 ) {
const int err = errno;
free( map );
logadd( LOG_WARNING, "Could not open file to write cache map to disk (errno=%d) file %s", err, mapfile );
return false;
}
size_t done = 0;
while ( done < size ) {
const ssize_t ret = write( fd, map, size - done );
if ( ret == -1 ) {
if ( errno == EINTR ) continue;
logadd( LOG_WARNING, "Could not write cache map (errno=%d) file %s", errno, mapfile );
break;
}
if ( ret <= 0 ) {
logadd( LOG_WARNING, "Unexpected return value %d for write() to %s", (int)ret, mapfile );
break;
}
done += (size_t)ret;
}
if ( fsync( fd ) == -1 ) {
logadd( LOG_WARNING, "fsync() on image map %s failed with errno %d", mapfile, errno );
}
close( fd );
free( map );
return true;
}
static bool uplink_connectionShouldShutdown(dnbd3_connection_t *link)
{
return ( link->idleTime > SERVER_UPLINK_IDLE_TIMEOUT && _backgroundReplication != BGR_FULL );
}