#include "uplink.h"
#include "locks.h"
#include "memlog.h"
#include "sockhelper.h"
#include "image.h"
#include "helper.h"
#include "altservers.h"
#include <pthread.h>
#include <sys/socket.h>
#include <string.h>
#include <sys/epoll.h>
#include <sys/errno.h>
#include <assert.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <inttypes.h>
static void* uplink_mainloop(void *data);
static void uplink_send_requests(dnbd3_connection_t *link, int newOnly);
static void uplink_handle_receive(dnbd3_connection_t *link);
// ############ uplink connection handling
/**
* Create and initialize an uplink instance for the given
* image. Uplinks run in their own thread.
* Locks on: _images[].lock
*/
int uplink_init(dnbd3_image_t *image)
{
dnbd3_connection_t *link = NULL;
assert( image != NULL );
spin_lock( &image->lock );
assert( image->uplink == NULL );
if ( image->cache_map == NULL ) {
memlogf( "[WARNING] Uplink was requested for image %s, but it is already complete", image->lower_name );
goto failure;
}
link = image->uplink = calloc( 1, sizeof(dnbd3_connection_t) );
link->image = image;
link->queueLen = 0;
link->fd = -1;
link->signal = -1;
link->betterFd = -1;
link->rttTestResult = RTT_IDLE;
link->recvBufferLen = 0;
link->shutdown = FALSE;
spin_init( &link->queueLock, PTHREAD_PROCESS_PRIVATE );
if ( 0 != pthread_create( &(link->thread), NULL, &uplink_mainloop, (void *)(uintptr_t)link ) ) {
memlogf( "[ERROR] Could not start thread for new client." );
goto failure;
}
spin_unlock( &image->lock );
return TRUE;
failure: ;
if ( link != NULL ) free( link );
link = image->uplink = NULL;
spin_unlock( &image->lock );
return FALSE;
}
void uplink_shutdown(dnbd3_image_t *image)
{
assert( image != NULL );
if ( image->uplink == NULL || image->uplink->shutdown ) return;
dnbd3_connection_t * const uplink = image->uplink;
spin_lock( &uplink->queueLock );
image->uplink = NULL;
uplink->shutdown = TRUE;
spin_unlock( &uplink->queueLock );
spin_destroy( &uplink->queueLock );
if ( uplink->signal != -1 ) write( uplink->signal, "", 1 );
if ( uplink->image != NULL ) {
pthread_join( uplink->thread, NULL );
}
free( uplink->recvBuffer );
free( uplink );
}
/**
* Request a chunk of data through an uplink server
*/
int uplink_request(dnbd3_client_t *client, uint64_t handle, uint64_t start, uint32_t length)
{
if ( client == NULL || client->image == NULL ) return FALSE;
spin_lock( &client->image->lock );
if ( client->image->uplink == NULL ) {
spin_unlock( &client->image->lock );
return FALSE;
}
dnbd3_connection_t * const uplink = client->image->uplink;
int foundExisting = FALSE; // Is there a pending request that is a superset of our range?
int i;
int freeSlot = -1;
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;
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 ) {
foundExisting = TRUE;
break;
}
}
if ( freeSlot == -1 ) {
if ( uplink->queueLen >= SERVER_MAX_UPLINK_QUEUE ) {
spin_unlock( &uplink->queueLock );
memlogf( "[WARNING] Uplink queue is full, consider increasing SERVER_MAX_UPLINK_QUEUE. Dropping client..." );
return FALSE;
}
freeSlot = uplink->queueLen++;
}
uplink->queue[freeSlot].from = start;
uplink->queue[freeSlot].to = end;
uplink->queue[freeSlot].handle = handle;
uplink->queue[freeSlot].client = client;
uplink->queue[freeSlot].status = (foundExisting ? ULR_PENDING : ULR_NEW);
spin_unlock( &uplink->queueLock );
if ( !foundExisting ) {
write( uplink->signal, "", 1 );
}
return TRUE;
}
/**
* Uplink thread.
* Locks are irrelevant as this is never called from another function
*/
static void* uplink_mainloop(void *data)
{
const int MAXEVENTS = 3;
struct epoll_event ev, events[MAXEVENTS];
dnbd3_connection_t *link = (dnbd3_connection_t*)data;
int fdEpoll = -1, fdPipe = -1;
int numSocks, i, waitTime;
int altCheckInterval = SERVER_RTT_DELAY_INIT;
int bFree = FALSE;
time_t nextAltCheck = 0;
char buffer[100];
//
assert( link != NULL );
assert( link->queueLen == 0 );
//
fdEpoll = epoll_create( 2 );
if ( fdEpoll == -1 ) {
memlogf( "[WARNING] epoll_create failed. Uplink unavailable." );
goto cleanup;
}
{
int pipes[2];
if ( pipe( pipes ) < 0 ) {
memlogf( "[WARNING] error creating pipe. Uplink unavailable." );
goto cleanup;
}
sock_set_nonblock( pipes[0] );
sock_set_nonblock( pipes[1] );
fdPipe = pipes[0];
link->signal = pipes[1];
memset( &ev, 0, sizeof(ev) );
ev.events = EPOLLIN;
ev.data.fd = fdPipe;
if ( epoll_ctl( fdEpoll, EPOLL_CTL_ADD, fdPipe, &ev ) < 0 ) {
memlogf( "[WARNING] adding signal-pipe to epoll set failed" );
goto cleanup;
}
}
while ( !_shutdown && !link->shutdown ) {
// epoll()
if ( link->fd == -1 ) {
waitTime = 1500;
} else {
waitTime = (time( NULL ) - nextAltCheck) * 1000;
if ( waitTime < 1500 ) waitTime = 1500;
}
numSocks = epoll_wait( fdEpoll, events, MAXEVENTS, waitTime );
if ( _shutdown || link->shutdown ) goto cleanup;
if ( numSocks < 0 ) { // Error?
memlogf( "[DEBUG] epoll_wait() error %d", (int)errno);
usleep( 10000 );
continue;
}
for (i = 0; i < numSocks; ++i) { // Check all events
if ( (events[i].events & (EPOLLERR | EPOLLHUP)) || !(events[i].events & EPOLLIN) ) {
if ( events[i].data.fd == fdPipe ) {
memlogf( "[WARNING] epoll error on signal-pipe!" );
goto cleanup;
}
if ( events[i].data.fd == link->fd ) {
link->fd = -1;
close( events[i].data.fd );
printf( "[DEBUG] Uplink gone away, panic!\n" );
nextAltCheck = 0;
} else {
printf( "[DEBUG] Error on unknown FD in uplink epoll" );
close( events[i].data.fd );
}
continue;
}
// No error, handle normally
if ( events[i].data.fd == fdPipe ) {
int ret;
do {
ret = read( fdPipe, buffer, sizeof buffer );
} while ( ret > 0 ); // Throw data away, this is just used for waking this thread up
if ( ret == 0 ) {
memlogf( "[WARNING] Signal pipe of uplink for %s closed! Things will break!", link->image->lower_name );
}
ret = errno;
if ( ret != EAGAIN && ret != EWOULDBLOCK && ret != EBUSY && ret != EINTR ) {
memlogf( "[WARNING] Errno %d on pipe-read on uplink for %s! Things will break!", ret, link->image->lower_name );
}
if ( link->fd != -1 ) {
uplink_send_requests( link, TRUE );
}
} else if ( events[i].data.fd == link->fd ) {
uplink_handle_receive( link );
if ( link->fd == -1 ) nextAltCheck = 0;
if ( _shutdown || link->shutdown ) goto cleanup;
} else {
printf( "[DEBUG] Sanity check: unknown FD ready on epoll! Closing...\n" );
close( events[i].data.fd );
}
}
// Done handling epoll sockets
// Check if server switch is in order
if ( link->rttTestResult == RTT_DOCHANGE ) {
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;
if ( fd != -1 ) close( fd );
// Re-send all pending requests
uplink_send_requests( link, FALSE );
link->betterFd = -1;
link->currentServer = link->betterServer;
link->image->working = TRUE;
if ( host_to_string( &link->currentServer, buffer, sizeof buffer ) ) {
printf( "[DEBUG] Now connected to %s\n", buffer );
}
memset( &ev, 0, sizeof(ev) );
ev.events = EPOLLIN;
ev.data.fd = link->fd;
if ( epoll_ctl( fdEpoll, EPOLL_CTL_ADD, link->fd, &ev ) < 0 ) {
memlogf( "[WARNING] adding uplink to epoll set failed" );
goto cleanup;
}
nextAltCheck = time( NULL ) + altCheckInterval;
// The rtt worker already did the handshake for our image, so there's nothing
// more to do here
}
// See if we should trigger a RTT measurement
if ( link->rttTestResult == RTT_IDLE || link->rttTestResult == RTT_DONTCHANGE ) {
const time_t now = time( NULL );
if ( nextAltCheck - now > SERVER_RTT_DELAY_MAX ) {
// This probably means the system time was changed - handle this case properly by capping the timeout
nextAltCheck = now + SERVER_RTT_DELAY_MAX;
} else if ( now >= nextAltCheck ) {
// It seems it's time for a check
if ( image_is_complete( link->image ) ) {
// Quit work if image is complete
if ( spin_trylock( &link->image->lock ) == 0 ) {
if ( link->image->cache_map != NULL ) {
free( link->image->cache_map );
link->image->cache_map = NULL;
}
link->image->uplink = NULL;
link->shutdown = TRUE;
free( link->recvBuffer );
link->recvBuffer = NULL;
bFree = TRUE;
spin_lock( &link->queueLock );
spin_unlock( &link->queueLock );
spin_destroy( &link->queueLock );
spin_unlock( &link->image->lock );
pthread_detach( link->thread );
goto cleanup;
}
} else {
// Not complete- do measurement
altserver_find_uplink( link ); // This will set RTT_INPROGRESS (synchronous)
}
altCheckInterval = MIN(altCheckInterval + 1, SERVER_RTT_DELAY_MAX);
nextAltCheck = now + altCheckInterval;
}
}
}
cleanup: ;
const int fd = link->fd;
const int signal = link->signal;
link->fd = -1;
link->signal = -1;
if ( fd != -1 ) close( fd );
if ( signal != -1 ) close( signal );
if ( fdPipe != -1 ) close( fdPipe );
if ( fdEpoll != -1 ) close( fdEpoll );
// 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 );
if ( bFree ) free( link );
return NULL ;
}
static void uplink_send_requests(dnbd3_connection_t *link, int newOnly)
{
// Scan for new requests
int j;
dnbd3_request_t request;
request.magic = dnbd3_packet_magic;
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;
request.handle = link->queue[j].from; // HACK: Store offset in handle too, as it won't be included in the reply
request.cmd = CMD_GET_BLOCK;
request.offset = link->queue[j].from;
request.size = link->queue[j].to - link->queue[j].from;
spin_unlock( &link->queueLock );
fixup_request( request );
const int ret = write( link->fd, &request, sizeof request );
if ( ret != sizeof(request) ) {
// 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.
printf( "[DEBUG] Error sending request to uplink server!" );
}
spin_lock( &link->queueLock );
}
spin_unlock( &link->queueLock );
}
/**
* Receive data from uplink server and process/dispatch
* Locks on: link.lock, indirectly on images[].lock
*/
static void uplink_handle_receive(dnbd3_connection_t *link)
{
dnbd3_reply_t reply;
int ret, i;
ret = recv( link->fd, &reply, sizeof reply, MSG_WAITALL );
if ( ret != sizeof reply ) {
memlogf( "[INFO] Lost connection to uplink server for %s", link->image->path );
goto error_cleanup;
}
fixup_reply( reply );
if ( reply.magic != dnbd3_packet_magic ) {
memlogf( "[WARNING] Uplink server's packet did not start with dnbd3_packet_magic (%s)", link->image->path );
goto error_cleanup;
}
if ( reply.size > 9000000 ) {
memlogf( "[WARNING] Pure evil: Uplink server sent too much payload for %s", link->image->path );
goto error_cleanup;
}
if ( link->recvBufferLen < reply.size ) {
if ( link->recvBuffer != NULL ) free( link->recvBuffer );
link->recvBufferLen = MIN(9000000, reply.size + 8192);
link->recvBuffer = malloc( link->recvBufferLen );
}
uint32_t done = 0;
while ( done < reply.size ) {
ret = recv( link->fd, link->recvBuffer + done, reply.size - done, 0 );
if ( ret <= 0 ) {
memlogf( "[INFO] Lost connection to uplink server of", link->image->path );
goto error_cleanup;
}
done += ret;
}
// Payload read completely
// Bail out if we're not interested
if ( reply.cmd != CMD_GET_BLOCK ) return;
// Is a legit block reply
const uint64_t start = reply.handle;
const uint64_t end = reply.handle + reply.size;
// 1) Write to cache file
assert( link->image->cacheFd != -1 );
if ( lseek( link->image->cacheFd, start, SEEK_SET ) != start ) {
memlogf( "[ERROR] lseek() failed when writing to cache for %s", link->image->path );
} else {
ret = (int)write( link->image->cacheFd, link->recvBuffer, reply.size );
if ( ret > 0 ) image_update_cachemap( link->image, start, start + ret, TRUE );
}
// 2) Figure out which clients are interested in it
struct iovec iov[2];
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 ) continue;
if ( req->from >= start && req->to <= end ) { // Match :-)
req->status = ULR_PROCESSING;
}
}
// 3) Send to interested clients
reply.magic = dnbd3_packet_magic; // !! re-using reply struct - do not read from it after here
for (i = link->queueLen - 1; i >= 0; --i) {
dnbd3_queued_request_t * const req = &link->queue[i];
if ( req->status != ULR_PROCESSING ) continue;
assert( req->from >= start && req->to <= end );
reply.cmd = CMD_GET_BLOCK;
reply.handle = req->handle;
reply.size = req->to - req->from;
iov[0].iov_base = &reply;
iov[0].iov_len = sizeof reply;
iov[1].iov_base = link->recvBuffer + (req->from - start);
iov[1].iov_len = reply.size;
fixup_reply( reply );
spin_unlock( &link->queueLock );
// send: Don't care about errors here, let the client
// connection thread deal with it if something goes wrong
pthread_mutex_lock( &req->client->sendMutex );
writev( req->client->sock, iov, 2 );
pthread_mutex_unlock( &req->client->sendMutex );
spin_lock( &link->queueLock );
req->status = ULR_FREE;
if ( i > 20 && i == link->queueLen - 1 ) link->queueLen--;
}
spin_unlock( &link->queueLock );
return;
error_cleanup: ;
const int fd = link->fd;
link->fd = -1;
if ( fd != -1 ) close( fd );
return;
}
