src/workprover/Readme.md

@@ -0,0 +1,42 @@
+Please keep this module independent from the outside code, so that it can be reused in other applications.
+
+If you are going to use it, you should wrap your program's main file in this:
+
+```python
+import workprover.dumbsolver
+
+workprover.dumbsolver.libcrypto = ...
+
+if __name__ == "__main__":
+    import multiprocessing
+
+    multiprocessing.freeze_support()
+
+    ...
+```
+
+See the `multiprocessing` module documentation for explaination.
+
+Build fast solver
+-----------------
+
+On Linux, BSDs or MacOS: `make -C fastsolver`.
+
+On Windows:
+
+- Install OpenSSL. Build it yourself or install [third-party](https://wiki.openssl.org/index.php/Binaries) prebuilt binaries.
+
+- Install MSVC as part of Visual Studio or standalone. Official offline installer: https://aka.ms/vcpython27.
+
+- Open its command line and go to the `fastsolver` directory.
+
+- Add OpenSSL paths to environment variables:
+
+```bat
+set INCLUDE=C:\OpenSSL-Win64\include;%INCLUDE%
+set LIB=C:\OpenSSL-Win64\lib;%LIB%
+```
+
+- Do `cl @options.txt`.
+
+- Append the `-32` or `-64` suffix to the DLL file name.

src/workprover/__init__.py

@@ -0,0 +1,238 @@
+import sys
+import multiprocessing
+import time
+import struct
+import threading
+import Queue
+import collections
+
+import utils
+import dumbsolver
+import forkingsolver
+import fastsolver
+import gpusolver
+
+timeout = .5
+
+class Stop(Exception):
+    pass
+
+class Task(object):
+    previous = None
+    next = None
+
+    def __init__(self, headlessPayload, TTL, expiryTime, target):
+        self.headlessPayload = headlessPayload
+        self.TTL = TTL
+        self.expiryTime = expiryTime
+        self.target = target
+
+class WorkProver(threading.Thread):
+    def __init__(self, codePath, GPUVendors, seed, statusUpdated):
+        super(self.__class__, self).__init__()
+
+        self.availableSolvers = {
+            "dumb": dumbsolver.DumbSolver(codePath)
+        }
+
+        # Comment from the previous version:
+
+        # on my (Peter Surda) Windows 10, Windows Defender
+        # does not like this and fights with PyBitmessage
+        # over CPU, resulting in very slow PoW
+        # added on 2015-11-29: multiprocesing.freeze_support() doesn't help
+
+        if not hasattr(sys, "frozen") or sys.frozen == "macosx_app":
+            self.availableSolvers["forking"] = forkingsolver.ForkingSolver(codePath)
+
+        try:
+            self.availableSolvers["fast"] = fastsolver.FastSolver(codePath)
+        except:
+            pass
+
+        try:
+            self.availableSolvers["gpu"] = gpusolver.GPUSolver(codePath, GPUVendors)
+        except:
+            pass
+
+        try:
+            self.defaultParallelism = multiprocessing.cpu_count()
+        except NotImplementedError:
+            self.defaultParallelism = 1
+
+        self.seed = seed
+        self.roundsCounter = 0
+        self.statusUpdated = statusUpdated
+
+        self.commandsQueue = Queue.Queue()
+        self.resultsQueue = Queue.Queue()
+
+        self.solverName = None
+        self.solver = None
+
+        self.lastTime = utils.getTimePoint()
+        self.timedIntervals = collections.deque()
+        self.speed = 0
+
+        self.tasks = {}
+        self.currentTaskID = None
+
+    def notifyStatus(self):
+        if self.statusUpdated is None:
+            return
+
+        if self.solver is None:
+            parallelism = 0
+        else:
+            parallelism = self.solver.parallelism
+
+        self.statusUpdated((self.solverName, parallelism, self.speed))
+
+    def setSolver(self, name, parallelism):
+        if name is None and self.solverName is None:
+            pass
+        elif name == self.solverName:
+            if self.solver.parallelism != parallelism:
+                self.solver.setParallelism(parallelism)
+        else:
+            if self.solver is not None:
+                self.solver.setParallelism(0)
+                self.solverName = None
+                self.solver = None
+
+            if name is not None:
+                if name not in self.availableSolvers:
+                    name, parallelism = "dumb", 1
+
+                self.solverName = name
+                self.solver = self.availableSolvers[name]
+                self.solver.setParallelism(parallelism)
+
+        self.notifyStatus()
+
+    def updateSpeed(self, iterationsCount):
+        currentTime = utils.getTimePoint()
+        duration = currentTime - self.lastTime
+        self.lastTime = currentTime
+
+        self.timedIntervals.append((currentTime, iterationsCount, duration))
+
+        for i in xrange(len(self.timedIntervals)):
+            time, iterationsCount, duration = self.timedIntervals[0]
+
+            if time + duration < currentTime - 3:
+                self.timedIntervals.popleft()
+
+        totalDuration = 0
+        totalIterationsCount = 0
+
+        for time, iterationsCount, duration in self.timedIntervals:
+            totalIterationsCount += iterationsCount
+            totalDuration += duration
+
+        if totalDuration < .25:
+            self.speed = 0
+        else:
+            self.speed = totalIterationsCount / totalDuration
+
+        self.notifyStatus()
+
+    def addTask(self, ID, headlessPayload, TTL, expiryTime, byteDifficulty, lengthExtension):
+        target = utils.calculateTarget(8 + 8 + len(headlessPayload), TTL, byteDifficulty, lengthExtension)
+
+        task = Task(headlessPayload, TTL, expiryTime, target)
+
+        self.tasks[ID] = task
+
+        if self.currentTaskID is None:
+            task.previous = ID
+            task.next = ID
+
+            self.currentTaskID = ID
+        else:
+            task.previous = self.currentTaskID
+            task.next = self.tasks[self.currentTaskID].next
+
+            self.tasks[task.previous].next = ID
+            self.tasks[task.next].previous = ID
+
+    def cancelTask(self, ID):
+        if ID not in self.tasks:
+            return
+
+        task = self.tasks.pop(ID)
+
+        if len(self.tasks) == 0:
+            self.currentTaskID = None
+        else:
+            self.tasks[task.previous].next = task.next
+            self.tasks[task.next].previous = task.previous
+
+            if self.currentTaskID == ID:
+                self.currentTaskID = task.next
+
+    def nextTask(self):
+        self.currentTaskID = self.tasks[self.currentTaskID].next
+
+    def shutdown(self):
+        self.setSolver(None, 0)
+
+        for i in self.tasks.keys():
+            self.cancelTask(i)
+
+        raise Stop()
+
+    def processCommand(self, command, *arguments):
+        getattr(self, command)(*arguments)
+
+    def round(self):
+        while True:
+            try:
+                self.processCommand(*self.commandsQueue.get_nowait())
+            except Queue.Empty:
+                break
+
+        while self.solver is None or self.currentTaskID is None:
+            try:
+                self.processCommand(*self.commandsQueue.get(True, timeout))
+            except Queue.Empty:
+                self.updateSpeed(0)
+
+        task = self.tasks[self.currentTaskID]
+
+        if task.expiryTime is None:
+            expiryTime = int(time.time() + task.TTL)
+        else:
+            expiryTime = task.expiryTime
+
+        initialPayload = struct.pack(">Q", expiryTime) + task.headlessPayload
+        initialHash = utils.calculateInitialHash(initialPayload)
+
+        appendedSeed = self.seed + struct.pack(">Q", self.roundsCounter)
+        self.roundsCounter += 1
+
+        try:
+            nonce, iterationsCount = self.solver.search(initialHash, task.target, appendedSeed, timeout)
+        except gpusolver.GPUSolverError:
+            self.setSolver("dumb", 1)
+            self.availableSolvers.pop("gpu")
+
+            nonce, iterationsCount = None, 0
+
+        self.updateSpeed(iterationsCount)
+
+        if nonce is None:
+            self.nextTask()
+        else:
+            self.resultsQueue.put(("taskDone", self.currentTaskID, nonce, expiryTime))
+
+            self.cancelTask(self.currentTaskID)
+
+    def run(self):
+        try:
+            while True:
+                self.round()
+        except Stop:
+            return
+        except Exception as exception:
+            self.resultsQueue.put(exception)

src/workprover/dumbsolver.py

@@ -0,0 +1,70 @@
+import ctypes
+import struct
+import hashlib
+
+import utils
+
+libcrypto = None
+
+class DumbSolver(object):
+    def __init__(self, codePath):
+        libcrypto.SHA512.restype = ctypes.c_void_p
+
+        self.prefixes = [chr(i) for i in xrange(256)]
+
+        if ctypes.c_size_t is ctypes.c_uint:
+            self.proofLength = 8 + 64
+            self.hashLength = 64
+        else:
+            # Using the wrapper instead of a clear number slows the work down, but otherwise seems to be unsafe
+
+            self.proofLength = ctypes.c_size_t(8 + 64)
+            self.hashLength = ctypes.c_size_t(64)
+
+        self.firstHash = ctypes.create_string_buffer(64)
+        self.secondHash = ctypes.create_string_buffer(64)
+
+        self.parallelism = 1
+
+    def search(self, initialHash, target, seed, timeout):
+        startTime = utils.getTimePoint()
+
+        sha512 = libcrypto.SHA512
+
+        prefixes = self.prefixes
+        proofLength = self.proofLength
+        hashLength = self.hashLength
+        firstHash = self.firstHash
+        secondHash = self.secondHash
+
+        encodedTarget = struct.pack(">Q", target)
+
+        solutions = []
+        i = 0
+
+        while True:
+            randomness = hashlib.sha512(seed + struct.pack(">Q", i)).digest()
+            i += 1
+
+            suffix = randomness[: 7] + initialHash
+
+            for j in prefixes:
+                proof = j + suffix
+
+                sha512(j + suffix, proofLength, firstHash)
+                sha512(firstHash, hashLength, secondHash)
+
+                if secondHash[: 8] <= encodedTarget:
+                    solutions.append(proof[: 8])
+
+            if len(solutions) != 0:
+                index, = struct.unpack(">Q", randomness[7: 15])
+                nonce = solutions[index % len(solutions)]
+
+                return nonce, 256 * i
+
+            if utils.getTimePoint() - startTime >= timeout:
+                return None, 256 * i
+
+    def setParallelism(self, parallelism):
+        pass

src/workprover/fastsolver.py

@@ -0,0 +1,71 @@
+import sys
+import os.path
+import platform
+import subprocess
+import ctypes
+
+def loadFastSolver(codePath):
+    if hasattr(sys, "winver"):
+        suffix = "-32"
+
+        if platform.architecture()[0] == "64bit":
+            suffix = "-64"
+
+        path = os.path.join(codePath, "fastsolver/libfastsolver{}.dll".format(suffix))
+
+        return ctypes.WinDLL(path)
+
+    makePath = os.path.join(codePath, "fastsolver")
+    path = os.path.join(codePath, "fastsolver/libfastsolver.so")
+
+    try:
+        return ctypes.CDLL(path)
+    except:
+        if not hasattr(sys, "frozen"):
+            subprocess.call(["make", "-C", makePath])
+
+            return ctypes.CDLL(path)
+        else:
+            raise Exception()
+
+class FastSolver(object):
+    def __init__(self, codePath):
+        self.libfastsolver = loadFastSolver(codePath)
+
+        self.libfastsolver.fastsolver_add.restype = ctypes.c_size_t
+        self.libfastsolver.fastsolver_add.argtypes = []
+
+        self.libfastsolver.fastsolver_remove.restype = ctypes.c_size_t
+        self.libfastsolver.fastsolver_remove.argtypes = [ctypes.c_size_t]
+
+        self.libfastsolver.fastsolver_search.restype = ctypes.c_int
+
+        self.libfastsolver.fastsolver_search.argtypes = [
+            ctypes.c_void_p, ctypes.c_void_p,
+            ctypes.c_void_p, ctypes.c_ulonglong, ctypes.c_void_p, ctypes.c_ulonglong
+        ]
+
+        self.nonce = ctypes.create_string_buffer(8)
+        self.iterationsCount = ctypes.c_ulonglong()
+
+        self.parallelism = 0
+
+    def search(self, initialHash, target, seed, timeout):
+        found = self.libfastsolver.fastsolver_search(
+            self.nonce, ctypes.byref(self.iterationsCount),
+            initialHash, target, seed, long(1000000000 * timeout)
+        )
+
+        if found == 1:
+            return self.nonce.raw, self.iterationsCount.value
+        else:
+            return None, self.iterationsCount.value
+
+    def setParallelism(self, parallelism):
+        parallelism = min(4096, parallelism)
+
+        for i in xrange(self.parallelism, parallelism):
+            self.parallelism = self.libfastsolver.fastsolver_add()
+
+        if parallelism < self.parallelism:
+            self.parallelism = self.libfastsolver.fastsolver_remove(self.parallelism - parallelism)

src/workprover/fastsolver/common.c

@@ -0,0 +1,100 @@
+#include <string.h>
+
+#include <openssl/sha.h>
+
+#include "common.h"
+
+volatile int run;
+
+const char *initial_hash;
+unsigned long long target;
+const char *seed;
+
+static void encode_big_endian(char *result, unsigned long long number) {
+    result[0] = number >> 56;
+    result[1] = number >> 48 & 0xff;
+    result[2] = number >> 40 & 0xff;
+    result[3] = number >> 32 & 0xff;
+    result[4] = number >> 24 & 0xff;
+    result[5] = number >> 16 & 0xff;
+    result[6] = number >> 8 & 0xff;
+    result[7] = number & 0xff;
+}
+
+static unsigned long long decode_big_endian(const char *encoded) {
+    return (
+        (unsigned long long) encoded[0] << 56 |
+        (unsigned long long) encoded[1] << 48 |
+        (unsigned long long) encoded[2] << 40 |
+        (unsigned long long) encoded[3] << 32 |
+        (unsigned long long) encoded[4] << 24 |
+        (unsigned long long) encoded[5] << 16 |
+        (unsigned long long) encoded[6] << 8 |
+        (unsigned long long) encoded[7]
+    );
+}
+
+int work(char *nonce, unsigned long long *iterations_count, size_t thread_number) {
+    unsigned long long i;
+
+    char proof[8 + 64];
+    char appended_seed[SEED_LENGTH + 8 + 8];
+
+    memcpy(proof + 8, initial_hash, 64);
+    memcpy(appended_seed, seed, SEED_LENGTH);
+    encode_big_endian(appended_seed + SEED_LENGTH, thread_number);
+
+    for (i = 0; run; ++i) {
+        char randomness[64];
+
+        size_t solutions_count = 0;
+        char solutions[256];
+
+        size_t j;
+
+        encode_big_endian(appended_seed + SEED_LENGTH + 8, i);
+
+        SHA512((unsigned char *) appended_seed, SEED_LENGTH + 8 + 8, (unsigned char *) randomness);
+
+        memcpy(proof + 1, randomness, 7);
+
+        for (j = 0; j < 256; ++j) {
+            unsigned long long trial;
+
+            SHA512_CTX context;
+
+            char first_hash[64];
+            char second_hash[64];
+
+            proof[0] = j;
+
+            SHA512_Init(&context);
+            SHA512_Update(&context, (unsigned char *) proof, 8 + 64);
+            SHA512_Final((unsigned char *) first_hash, &context);
+
+            SHA512_Init(&context);
+            SHA512_Update(&context, (unsigned char *) first_hash, 64);
+            SHA512_Final((unsigned char *) second_hash, &context);
+
+            trial = decode_big_endian(second_hash);
+
+            if (trial <= target) {
+                solutions[solutions_count] = j;
+                ++solutions_count;
+            }
+
+            ++*iterations_count;
+        }
+
+        if (solutions_count != 0) {
+            unsigned long long index = decode_big_endian(randomness + 7);
+
+            nonce[0] = solutions[index % solutions_count];
+            memcpy(nonce + 1, proof + 1, 7);
+
+            return 1;
+        }
+    }
+
+    return 0;
+}

src/workprover/fastsolver/common.h

@@ -0,0 +1,13 @@
+#ifndef COMMON_H
+    #define COMMON_H
+
+    extern volatile int run;
+
+    #define SEED_LENGTH (32 + 8)
+
+    extern const char *initial_hash;
+    extern unsigned long long target;
+    extern const char *seed;
+
+    int work(char *nonce, unsigned long long *iterations_count, size_t thread_number);
+#endif

src/workprover/fastsolver/main.map

@@ -0,0 +1,4 @@
+{
+    global: fastsolver_*;
+    local: *;
+};

src/workprover/fastsolver/makefile

@@ -0,0 +1,11 @@
+CFLAGS += -std=gnu99 -Wall -Wextra -pedantic -O3 -fPIC
+LDFLAGS += -shared -lpthread -lcrypto -Wl,-version-script=main.map
+
+libfastsolver.so: main.map common.o pthread.o
+	$(CC) $(LDFLAGS) -o $@ common.o pthread.o
+
+common.o: common.h common.c
+pthread.o: common.h pthread.c
+
+clean:
+	rm -f common.o pthread.o libfastsolver.so

src/workprover/fastsolver/options.txt

@@ -0,0 +1 @@
+/Ox /MD common.c winapi.c /link /DLL /OUT:libfastsolver.dll /EXPORT:fastsolver_add /EXPORT:fastsolver_remove /EXPORT:fastsolver_search libcrypto.lib

src/workprover/fastsolver/pthread.c

@@ -0,0 +1,214 @@
+#include <string.h>
+#include <time.h>
+
+#include <pthread.h>
+
+#include "common.h"
+
+static int initialized;
+
+#define MAXIMUM_THREADS_COUNT 4096
+
+static size_t threads_count;
+static pthread_t threads[MAXIMUM_THREADS_COUNT];
+
+static pthread_mutex_t lock;
+static pthread_cond_t start;
+static pthread_cond_t done;
+
+static size_t running_threads_count;
+
+static int found;
+static char best_nonce[8];
+static unsigned long long total_iterations_count;
+
+static void *thread_function(void *argument) {
+    size_t thread_number = (pthread_t *) argument - threads;
+
+    while (1) {
+        char nonce[8];
+        unsigned long long iterations_count = 0;
+        int result;
+
+        pthread_mutex_lock(&lock);
+
+        while (!run && threads_count > thread_number) {
+            pthread_cond_wait(&start, &lock);
+        }
+
+        if (threads_count <= thread_number) {
+            pthread_mutex_unlock(&lock);
+
+            return NULL;
+        }
+
+        ++running_threads_count;
+
+        pthread_mutex_unlock(&lock);
+
+        result = work(nonce, &iterations_count, thread_number);
+
+        pthread_mutex_lock(&lock);
+
+        if (result == 1) {
+            found = 1;
+            memcpy(best_nonce, nonce, 8);
+        }
+
+        total_iterations_count += iterations_count;
+
+        run = 0;
+        --running_threads_count;
+
+        pthread_cond_signal(&done);
+        pthread_mutex_unlock(&lock);
+    }
+}
+
+static int initialize(void) {
+    pthread_condattr_t done_attributes;
+
+    if (initialized == 1) {
+        return 1;
+    }
+
+    if (pthread_mutex_init(&lock, NULL) != 0) {
+        goto error_lock;
+    }
+
+    if (pthread_cond_init(&start, NULL) != 0) {
+        goto error_start;
+    }
+
+    if (pthread_condattr_init(&done_attributes) != 0) {
+        goto error_done_attributes;
+    }
+
+    #ifndef __APPLE__
+        pthread_condattr_setclock(&done_attributes, CLOCK_MONOTONIC);
+    #endif
+
+    if (pthread_cond_init(&done, &done_attributes) != 0) {
+        goto error_done;
+    }
+
+    pthread_condattr_destroy(&done_attributes);
+
+    initialized = 1;
+
+    return 1;
+
+    error_done: pthread_condattr_destroy(&done_attributes);
+    error_done_attributes: pthread_cond_destroy(&start);
+    error_start: pthread_mutex_destroy(&lock);
+    error_lock: return 0;
+}
+
+size_t fastsolver_add(void) {
+    #ifdef SCHED_IDLE
+        int policy = SCHED_IDLE;
+    #else
+        int policy = SCHED_OTHER;
+    #endif
+
+    struct sched_param parameters;
+
+    if (initialize() == 0) {
+        return threads_count;
+    }
+
+    pthread_mutex_lock(&lock);
+
+    if (pthread_create(&threads[threads_count], NULL, thread_function, &threads[threads_count]) != 0) {
+        pthread_mutex_unlock(&lock);
+
+        return threads_count;
+    }
+
+    parameters.sched_priority = sched_get_priority_min(policy);
+    pthread_setschedparam(threads[threads_count], policy, &parameters);
+
+    ++threads_count;
+
+    pthread_mutex_unlock(&lock);
+
+    return threads_count;
+}
+
+size_t fastsolver_remove(size_t count) {
+    size_t i;
+
+    pthread_mutex_lock(&lock);
+
+    threads_count -= count;
+
+    pthread_cond_broadcast(&start);
+    pthread_mutex_unlock(&lock);
+
+    for (i = 0; i < count; ++i) {
+        void *result;
+
+        pthread_join(threads[threads_count + i], &result);
+    }
+
+    return threads_count;
+}
+
+int fastsolver_search(
+    char *local_nonce,
+    unsigned long long *local_iterations_count,
+    const char *local_initial_hash,
+    unsigned long long local_target,
+    const char *local_seed,
+    unsigned long long timeout
+) {
+    struct timespec wait_time;
+    unsigned long long nanoseconds;
+
+    initial_hash = local_initial_hash;
+    target = local_target;
+    seed = local_seed;
+
+    found = 0;
+    total_iterations_count = 0;
+
+    #ifdef __APPLE__
+        wait_time.tv_sec = 0;
+        wait_time.tv_nsec = 0;
+    #else
+        clock_gettime(CLOCK_MONOTONIC, &wait_time);
+    #endif
+
+    nanoseconds = wait_time.tv_nsec + timeout;
+
+    wait_time.tv_sec += nanoseconds / 1000000000;
+    wait_time.tv_nsec = nanoseconds % 1000000000;
+
+    pthread_mutex_lock(&lock);
+
+    run = 1;
+
+    pthread_cond_broadcast(&start);
+
+    #ifdef __APPLE__
+        pthread_cond_timedwait_relative_np(&done, &lock, &wait_time);
+    #else
+        pthread_cond_timedwait(&done, &lock, &wait_time);
+    #endif
+
+    run = 0;
+
+    while (running_threads_count != 0) {
+        pthread_cond_wait(&done, &lock);
+    }
+
+    pthread_mutex_unlock(&lock);
+
+    if (found) {
+        memcpy(local_nonce, best_nonce, 8);
+    }
+
+    *local_iterations_count = total_iterations_count;
+
+    return found;
+}

src/workprover/fastsolver/winapi.c

@@ -0,0 +1,160 @@
+#include <string.h>
+
+#include <Windows.h>
+
+#include "common.h"
+
+static int initialized;
+
+#define MAXIMUM_THREADS_COUNT 4096
+
+static size_t threads_count;
+static HANDLE threads[MAXIMUM_THREADS_COUNT];
+
+static CRITICAL_SECTION lock;
+static CONDITION_VARIABLE start = CONDITION_VARIABLE_INIT;
+static CONDITION_VARIABLE done = CONDITION_VARIABLE_INIT;
+
+static size_t running_threads_count;
+
+static int found;
+static char best_nonce[8];
+static unsigned long long total_iterations_count;
+
+DWORD WINAPI thread_function(LPVOID argument) {
+    size_t thread_number = (HANDLE *) argument - threads;
+
+    while (1) {
+        char nonce[8];
+        unsigned long long iterations_count = 0;
+        int result;
+
+        EnterCriticalSection(&lock);
+
+        while (!run && threads_count > thread_number) {
+            SleepConditionVariableCS(&start, &lock, INFINITE);
+        }
+
+        if (threads_count <= thread_number) {
+            LeaveCriticalSection(&lock);
+
+            return 0;
+        }
+
+        ++running_threads_count;
+
+        LeaveCriticalSection(&lock);
+
+        result = work(nonce, &iterations_count, thread_number);
+
+        EnterCriticalSection(&lock);
+
+        if (result == 1) {
+            found = 1;
+            memcpy(best_nonce, nonce, 8);
+        }
+
+        total_iterations_count += iterations_count;
+
+        run = 0;
+        --running_threads_count;
+
+        WakeConditionVariable(&done);
+        LeaveCriticalSection(&lock);
+    }
+}
+
+static int initialize(void) {
+    if (initialized == 1) {
+        return 1;
+    }
+
+    InitializeCriticalSection(&lock);
+
+    initialized = 1;
+
+    return 1;
+}
+
+size_t fastsolver_add(void) {
+    if (initialize() == 0) {
+        return threads_count;
+    }
+
+    EnterCriticalSection(&lock);
+
+    threads[threads_count] = CreateThread(NULL, 0, thread_function, &threads[threads_count], 0, NULL);
+
+    if (threads[threads_count] == NULL) {
+        LeaveCriticalSection(&lock);
+
+        return threads_count;
+    }
+
+    SetThreadPriority(threads[threads_count], THREAD_PRIORITY_IDLE);
+
+    ++threads_count;
+
+    LeaveCriticalSection(&lock);
+
+    return threads_count;
+}
+
+size_t fastsolver_remove(size_t count) {
+    size_t i;
+
+    EnterCriticalSection(&lock);
+
+    threads_count -= count;
+
+    WakeAllConditionVariable(&start);
+    LeaveCriticalSection(&lock);
+
+    WaitForMultipleObjects(count, threads + threads_count, TRUE, INFINITE);
+
+    for (i = 0; i < count; ++i) {
+        CloseHandle(threads[threads_count + i]);
+    }
+
+    return threads_count;
+}
+
+int fastsolver_search(
+    char *local_nonce,
+    unsigned long long *local_iterations_count,
+    const char *local_initial_hash,
+    unsigned long long local_target,
+    const char *local_seed,
+    unsigned long long timeout
+) {
+    initial_hash = local_initial_hash;
+    target = local_target;
+    seed = local_seed;
+
+    found = 0;
+    total_iterations_count = 0;
+
+    EnterCriticalSection(&lock);
+
+    run = 1;
+
+    WakeAllConditionVariable(&start);
+
+    SleepConditionVariableCS(&done, &lock, timeout / 1000);
+
+    run = 0;
+
+    while (running_threads_count != 0) {
+        SleepConditionVariableCS(&done, &lock, INFINITE);
+    }
+
+    LeaveCriticalSection(&lock);
+
+    if (found) {
+        memcpy(local_nonce, best_nonce, 8);
+    }
+
+    *local_iterations_count = total_iterations_count;
+
+    return found;
+}

src/workprover/forkingsolver.py

@@ -0,0 +1,106 @@
+import os
+import multiprocessing
+import struct
+
+import dumbsolver
+
+def setIdle():
+    try:
+        import psutil
+
+        psutil.Process().nice(psutil.IDLE_PRIORITY_CLASS)
+
+        return
+    except:
+        pass
+
+    try:
+        import win32api
+        import win32con
+        import win32process
+
+        PID = win32api.GetCurrentProcessId()
+        handle = win32api.OpenProcess(win32con.PROCESS_ALL_ACCESS, True, PID)
+
+        win32process.SetPriorityClass(handle, win32process.IDLE_PRIORITY_CLASS)
+
+        return
+    except:
+        pass
+
+    if hasattr(os, "nice"):
+        os.nice(40)
+
+def threadFunction(local, remote, codePath, threadNumber):
+    remote.close()
+    setIdle()
+
+    solver = dumbsolver.DumbSolver(codePath)
+
+    while True:
+        received = local.recv()
+
+        command = received[0]
+        arguments = received[1: ]
+
+        if command == "search":
+            initialHash, target, seed, timeout = arguments
+            appendedSeed = seed + struct.pack(">Q", threadNumber)
+
+            nonce, iterationsCount = solver.search(initialHash, target, appendedSeed, timeout)
+
+            local.send(("done", nonce, iterationsCount))
+        elif command == "shutdown":
+            local.close()
+
+            return
+
+class ForkingSolver(object):
+    def __init__(self, codePath):
+        self.pipes = []
+        self.processes = []
+
+        self.parallelism = 0
+
+        self.codePath = codePath
+
+    def search(self, initialHash, target, seed, timeout):
+        for i in self.pipes:
+            i.send(("search", initialHash, target, seed, timeout))
+
+        bestNonce, totalIterationsCount = None, 0
+
+        for i in self.pipes:
+            event, nonce, iterationsCount = i.recv()
+
+            if nonce is not None:
+                bestNonce = nonce
+
+            totalIterationsCount += iterationsCount
+
+        return bestNonce, totalIterationsCount
+
+    def setParallelism(self, parallelism):
+        parallelism = min(4096, parallelism)
+
+        for i in xrange(self.parallelism, parallelism):
+            local, remote = multiprocessing.Pipe()
+
+            process = multiprocessing.Process(target = threadFunction, args = (remote, local, self.codePath, i))
+            process.start()
+
+            remote.close()
+
+            self.pipes.append(local)
+            self.processes.append(process)
+
+        for i in xrange(parallelism, self.parallelism):
+            pipe = self.pipes.pop()
+
+            pipe.send(("shutdown", ))
+            pipe.close()
+
+        for i in xrange(parallelism, self.parallelism):
+            self.processes.pop().join()
+
+        self.parallelism = parallelism

src/workprover/gpusolver.cl

@@ -0,0 +1,136 @@
+constant ulong k[80] = {
+    0x428a2f98d728ae22, 0x7137449123ef65cd, 0xb5c0fbcfec4d3b2f, 0xe9b5dba58189dbbc,
+    0x3956c25bf348b538, 0x59f111f1b605d019, 0x923f82a4af194f9b, 0xab1c5ed5da6d8118,
+    0xd807aa98a3030242, 0x12835b0145706fbe, 0x243185be4ee4b28c, 0x550c7dc3d5ffb4e2,
+    0x72be5d74f27b896f, 0x80deb1fe3b1696b1, 0x9bdc06a725c71235, 0xc19bf174cf692694,
+    0xe49b69c19ef14ad2, 0xefbe4786384f25e3, 0x0fc19dc68b8cd5b5, 0x240ca1cc77ac9c65,
+    0x2de92c6f592b0275, 0x4a7484aa6ea6e483, 0x5cb0a9dcbd41fbd4, 0x76f988da831153b5,
+    0x983e5152ee66dfab, 0xa831c66d2db43210, 0xb00327c898fb213f, 0xbf597fc7beef0ee4,
+    0xc6e00bf33da88fc2, 0xd5a79147930aa725, 0x06ca6351e003826f, 0x142929670a0e6e70,
+    0x27b70a8546d22ffc, 0x2e1b21385c26c926, 0x4d2c6dfc5ac42aed, 0x53380d139d95b3df,
+    0x650a73548baf63de, 0x766a0abb3c77b2a8, 0x81c2c92e47edaee6, 0x92722c851482353b,
+    0xa2bfe8a14cf10364, 0xa81a664bbc423001, 0xc24b8b70d0f89791, 0xc76c51a30654be30,
+    0xd192e819d6ef5218, 0xd69906245565a910, 0xf40e35855771202a, 0x106aa07032bbd1b8,
+    0x19a4c116b8d2d0c8, 0x1e376c085141ab53, 0x2748774cdf8eeb99, 0x34b0bcb5e19b48a8,
+    0x391c0cb3c5c95a63, 0x4ed8aa4ae3418acb, 0x5b9cca4f7763e373, 0x682e6ff3d6b2b8a3,
+    0x748f82ee5defb2fc, 0x78a5636f43172f60, 0x84c87814a1f0ab72, 0x8cc702081a6439ec,
+    0x90befffa23631e28, 0xa4506cebde82bde9, 0xbef9a3f7b2c67915, 0xc67178f2e372532b,
+    0xca273eceea26619c, 0xd186b8c721c0c207, 0xeada7dd6cde0eb1e, 0xf57d4f7fee6ed178,
+    0x06f067aa72176fba, 0x0a637dc5a2c898a6, 0x113f9804bef90dae, 0x1b710b35131c471b,
+    0x28db77f523047d84, 0x32caab7b40c72493, 0x3c9ebe0a15c9bebc, 0x431d67c49c100d4c,
+    0x4cc5d4becb3e42b6, 0x597f299cfc657e2a, 0x5fcb6fab3ad6faec, 0x6c44198c4a475817
+};
+
+constant ulong h[8] = {
+    0x6a09e667f3bcc908, 0xbb67ae8584caa73b, 0x3c6ef372fe94f82b, 0xa54ff53a5f1d36f1,
+    0x510e527fade682d1, 0x9b05688c2b3e6c1f, 0x1f83d9abfb41bd6b, 0x5be0cd19137e2179
+};
+
+#define ROTATE(x, n) ((x) >> (n) | (x) << 64 - (n))
+
+#define C(x, y, z) ((x) & (y) ^ ~(x) & (z))
+#define M(x, y, z) ((x) & (y) ^ (x) & (z) ^ (y) & (z))
+#define S0(x) (ROTATE((x), 28) ^ ROTATE((x), 34) ^ ROTATE((x), 39))
+#define S1(x) (ROTATE((x), 14) ^ ROTATE((x), 18) ^ ROTATE((x), 41))
+#define s0(x) (ROTATE((x), 1) ^ ROTATE((x), 8) ^ (x) >> 7)
+#define s1(x) (ROTATE((x), 19) ^ ROTATE((x), 61) ^ (x) >> 6)
+
+void sha512_process_block(ulong *state, ulong *block) {
+    ulong a = state[0];
+    ulong b = state[1];
+    ulong c = state[2];
+    ulong d = state[3];
+    ulong e = state[4];
+    ulong f = state[5];
+    ulong g = state[6];
+    ulong h = state[7];
+
+    ulong *w = block;
+
+    #pragma unroll
+
+    for (size_t i = 0; i < 16; i++) {
+        ulong t = k[i] + w[i & 15] + h + S1(e) + C(e, f, g);
+
+        h = g;
+        g = f;
+        f = e;
+        e = d + t;
+        t += M(a, b, c) + S0(a);
+        d = c;
+        c = b;
+        b = a;
+        a = t;
+    }
+
+    #pragma unroll 16
+
+    for (size_t i = 16; i < 80; i++) {
+        w[i & 15] += s0(w[i + 1 & 15]) + s1(w[i + 14 & 15]) + w[i + 9 & 15];
+
+        ulong t = k[i] + w[i & 15] + h + S1(e) + C(e, f, g);
+
+        h = g;
+        g = f;
+        f = e;
+        e = d + t;
+        t += M(a, b, c) + S0(a);
+        d = c;
+        c = b;
+        b = a;
+        a = t;
+    }
+
+    state[0] += a;
+    state[1] += b;
+    state[2] += c;
+    state[3] += d;
+    state[4] += e;
+    state[5] += f;
+    state[6] += g;
+    state[7] += h;
+}
+
+ulong compute_trial(ulong nonce, global const ulong *initial_hash) {
+    ulong fisrt_block[16] = {
+        nonce,
+        initial_hash[0], initial_hash[1], initial_hash[2], initial_hash[3],
+        initial_hash[4], initial_hash[5], initial_hash[6], initial_hash[7],
+        0x8000000000000000, 0, 0, 0, 0, 0, 8 * (8 + 64)
+    };
+
+    ulong second_block[16] = {
+        h[0], h[1], h[2], h[3],
+        h[4], h[5], h[6], h[7],
+        0x8000000000000000, 0, 0, 0, 0, 0, 0, 8 * 64
+    };
+
+    ulong double_hash[8] = {
+        h[0], h[1], h[2], h[3],
+        h[4], h[5], h[6], h[7]
+    };
+
+    sha512_process_block(second_block, fisrt_block);
+    sha512_process_block(double_hash, second_block);
+
+    return double_hash[0];
+}
+
+kernel void search(global unsigned int *output, global ulong *input) {
+    size_t thread_number = get_global_id(0);
+
+    global unsigned int *solutions_count = output;
+    global unsigned int *solutions = output + 1;
+
+    global ulong *nonce = input;
+    global ulong *initial_hash = input + 1;
+    global ulong *target = input + 9;
+
+    ulong trial = compute_trial(*nonce + thread_number, initial_hash);
+
+    if (trial <= *target) {
+        unsigned int index = atom_inc(solutions_count);
+
+        solutions[index] = thread_number;
+    }
+}

src/workprover/gpusolver.py

@@ -0,0 +1,103 @@
+import hashlib
+import struct
+import os.path
+
+import utils
+
+pyopencl = None
+numpy = None
+
+class GPUSolverError(Exception):
+    pass
+
+class GPUSolver(object):
+    def __init__(self, codePath, vendors = None):
+        global pyopencl, numpy
+
+        import pyopencl
+        import numpy
+
+        device = None
+
+        for i in pyopencl.get_platforms():
+            if vendors is not None and i.vendor not in vendors:
+                continue
+
+            devices = i.get_devices(device_type = pyopencl.device_type.GPU)
+
+            if len(devices) != 0:
+                device = devices[0]
+
+                break
+        else:
+            raise Exception()
+
+        context = pyopencl.Context(devices = [device])
+
+        computeUnitsCount = device.get_info(pyopencl.device_info.MAX_COMPUTE_UNITS)
+        workGroupSize = device.get_info(pyopencl.device_info.MAX_WORK_GROUP_SIZE)
+
+        self.parallelism = workGroupSize * computeUnitsCount
+        self.batchSize = self.parallelism * 256
+
+        self.queue = pyopencl.CommandQueue(context, device)
+
+        with open(os.path.join(codePath, "gpusolver.cl")) as file:
+            source = file.read()
+
+        program = pyopencl.Program(context, source).build()
+
+        self.hostOutput = numpy.zeros(1 + self.batchSize, numpy.uint32)
+        self.hostInput = numpy.zeros(1 + 8 + 1, numpy.uint64)
+
+        self.output = pyopencl.Buffer(context, pyopencl.mem_flags.READ_WRITE, 4 * (1 + self.batchSize))
+        self.input = pyopencl.Buffer(context, pyopencl.mem_flags.READ_ONLY, 8 * (1 + 8 + 1))
+
+        self.kernel = program.search
+        self.kernel.set_args(self.output, self.input)
+
+    def search(self, initialHash, target, seed, timeout):
+        startTime = utils.getTimePoint()
+
+        self.hostOutput[0] = 0
+
+        for i in xrange(8):
+            self.hostInput[1 + i], = struct.unpack(">Q", initialHash[8 * i: 8 * (i + 1)])
+
+        self.hostInput[9] = target
+
+        pyopencl.enqueue_copy(self.queue, self.output, self.hostOutput[: 1])
+
+        i = 0
+
+        while True:
+            randomness = hashlib.sha512(seed + struct.pack(">Q", i)).digest()
+            i += 1
+
+            self.hostInput[0], = struct.unpack(">Q", randomness[: 8])
+
+            pyopencl.enqueue_copy(self.queue, self.input, self.hostInput)
+            pyopencl.enqueue_nd_range_kernel(self.queue, self.kernel, (self.batchSize, ), None)
+            self.queue.finish()
+            pyopencl.enqueue_copy(self.queue, self.hostOutput[: 1], self.output)
+
+            solutionsCount = long(self.hostOutput[0])
+
+            if solutionsCount != 0:
+                pyopencl.enqueue_copy(self.queue, self.hostOutput[0: 1 + solutionsCount], self.output)
+
+                index, = struct.unpack(">Q", randomness[8: 16])
+                threadNumber = self.hostOutput[1 + index % solutionsCount]
+
+                nonce = struct.pack(">Q", long(self.hostInput[0]) + threadNumber)
+
+                if not utils.checkProof(nonce, initialHash, target):
+                    raise GPUSolverError()
+
+                return nonce, self.batchSize * i
+
+            if utils.getTimePoint() - startTime >= timeout:
+                return None, self.batchSize * i
+
+    def setParallelism(self, parallelism):
+        pass

src/workprover/test.py

@@ -0,0 +1,205 @@
+#!/usr/bin/env python2.7
+
+import unittest
+import os.path
+import binascii
+import struct
+import ctypes
+import ctypes.util
+import sys
+
+import __init__
+import utils
+import dumbsolver
+import forkingsolver
+import fastsolver
+import gpusolver
+
+codePath = os.path.dirname(__file__)
+
+if hasattr(sys, "winver"):
+	dumbsolver.libcrypto = ctypes.WinDLL("libcrypto.dll")
+else:
+	dumbsolver.libcrypto = ctypes.CDLL(ctypes.util.find_library("crypto"))
+
+nonce = binascii.unhexlify("9ca6790a249679f8")
+expiryTime = 1525845600
+
+headlessPayload = binascii.unhexlify("000000000001")
+initialPayload = struct.pack(">Q", expiryTime) + headlessPayload
+payload = nonce + initialPayload
+
+initialHash = binascii.unhexlify(
+    "1e87a288a10454dea0d3a9b606cc538db1b8b47fe8a21a37b8e57da3db6928eb"
+    "d854fd22aed3e1849c4a1c596fe0bfec266c05900a862c5b356a6b7e51a4b510"
+)
+
+doubleHash = binascii.unhexlify(
+    "16cdf04b739412bea1bf58d6c5a53ec92e7d4aab180213405bf10d615354d417"
+    "00f8b1510d0844a4b7c7b7434e6c115b52fcec5c591e96c31f4b8769ee683552"
+)
+
+TTL = 3600
+byteDifficulty = 1000
+lengthExtension = 1000
+
+target = 0x00000f903320b7f6
+
+seed = binascii.unhexlify("3941c24a1256660a8f65d962954c406dab7bc449317fa087c4a3f1a3ca7d95fd")
+timeout = .5
+
+class TestUtils(unittest.TestCase):
+    def testCalculateInitialHash(self):
+        self.assertEqual(utils.calculateInitialHash(initialPayload), initialHash)
+
+    def testCalculateDoubleHash(self):
+        self.assertEqual(utils.calculateDoubleHash(payload), doubleHash)
+
+    def testCalculateTarget(self):
+        self.assertEqual(utils.calculateTarget(1000, 1015, 1000, 1000), 0x00000843bf57fed2)
+        self.assertEqual(utils.calculateTarget(1000, 1016, 1000, 1000), 0x00000842b4a960c2)
+
+    def testCheckProof(self):
+        self.assertFalse(utils.checkProof(nonce, initialHash, 0x000002fe91eba355))
+        self.assertTrue(utils.checkProof(nonce, initialHash, 0x000002fe91eba356))
+
+    def testCheckWorkSufficient(self):
+        originalTime = utils.time.time
+
+        utils.time.time = lambda: expiryTime - 293757.5
+        self.assertFalse(utils.checkWorkSufficient(payload, byteDifficulty, lengthExtension))
+
+        utils.time.time = lambda: expiryTime - 293757
+        self.assertTrue(utils.checkWorkSufficient(payload, byteDifficulty, lengthExtension))
+
+        utils.time.time = originalTime
+
+    def testEstimateMaximumIterationsCount(self):
+        self.assertEqual(utils.estimateMaximumIterationsCount(0x000fffffffffffff, .1), 512)
+        self.assertEqual(utils.estimateMaximumIterationsCount(target, .8), 1735168)
+
+class TestSolver(unittest.TestCase):
+    def setUp(self):
+        self.solver = self.Solver(codePath)
+        self.solver.setParallelism(1)
+
+    def testSearch(self):
+        nonce = None
+
+        i = 0
+
+        while nonce is None:
+            appendedSeed = seed + struct.pack(">Q", i)
+            i += 1
+
+            nonce, iterationsCount = self.solver.search(initialHash, target, appendedSeed, timeout)
+
+        self.assertTrue(utils.checkProof(nonce, initialHash, target))
+
+    def tearDown(self):
+        self.solver.setParallelism(0)
+
+class TestDumbSolver(TestSolver):
+    Solver = dumbsolver.DumbSolver
+
+class TestForkingSolver(TestSolver):
+    Solver = forkingsolver.ForkingSolver
+
+class TestFastSolver(TestSolver):
+    Solver = fastsolver.FastSolver
+
+class TestGPUSolver(TestSolver):
+    Solver = gpusolver.GPUSolver
+
+class TestWorkProver(unittest.TestCase):
+    def setUp(self):
+        self.thread = __init__.WorkProver(codePath, None, seed, None)
+        self.thread.start()
+
+    def checkTaskLinks(self):
+        IDs = set(self.thread.tasks.keys())
+
+        if len(IDs) == 0:
+            return
+
+        self.assertIn(self.thread.currentTaskID, IDs)
+
+        linkID = next(iter(IDs))
+
+        for i in xrange(len(IDs)):
+            self.assertIn(linkID, IDs)
+
+            IDs.remove(linkID)
+
+            nextLinkID = self.thread.tasks[linkID].next
+
+            self.assertEqual(self.thread.tasks[nextLinkID].previous, linkID)
+
+            linkID = nextLinkID
+
+    def testTasks(self):
+        self.thread.addTask(0, headlessPayload, TTL, None, byteDifficulty, lengthExtension)
+
+        self.checkTaskLinks()
+
+        self.thread.addTask(1, headlessPayload, TTL, None, byteDifficulty, lengthExtension)
+        self.thread.addTask(2, headlessPayload, TTL, None, byteDifficulty, lengthExtension)
+
+        self.checkTaskLinks()
+
+        self.thread.cancelTask(self.thread.currentTaskID)
+        self.thread.nextTask()
+        self.thread.nextTask()
+        self.thread.nextTask()
+        self.thread.addTask(3, headlessPayload, TTL, None, byteDifficulty, lengthExtension)
+
+        self.checkTaskLinks()
+
+    def testSearch(self):
+        self.thread.commandsQueue.put((
+            "addTask", 0,
+            headlessPayload, TTL, None, byteDifficulty, lengthExtension
+        ))
+
+        self.thread.commandsQueue.put((
+            "addTask", 1,
+            headlessPayload, TTL, None, byteDifficulty, lengthExtension
+        ))
+
+        self.thread.commandsQueue.put((
+            "addTask", 2,
+            headlessPayload, TTL * 100, expiryTime, byteDifficulty, lengthExtension
+        ))
+
+        self.thread.commandsQueue.put(("setSolver", "dumb", 1))
+
+        for i in xrange(3):
+            event, ID, nonce, localExpiryTime = self.thread.resultsQueue.get()
+
+            initialPayload = struct.pack(">Q", localExpiryTime) + headlessPayload
+            initialHash = utils.calculateInitialHash(initialPayload)
+
+            self.assertTrue(utils.checkProof(nonce, initialHash, target))
+
+    def tearDown(self):
+        self.thread.commandsQueue.put(("shutdown", ))
+        self.thread.join()
+
+loader = unittest.TestLoader()
+
+suite = unittest.TestSuite([
+    loader.loadTestsFromTestCase(TestUtils),
+    loader.loadTestsFromTestCase(TestDumbSolver),
+    loader.loadTestsFromTestCase(TestForkingSolver),
+    loader.loadTestsFromTestCase(TestFastSolver),
+    loader.loadTestsFromTestCase(TestGPUSolver),
+    loader.loadTestsFromTestCase(TestWorkProver)
+])
+
+if __name__ == "__main__":
+    import multiprocessing
+
+    multiprocessing.freeze_support()
+
+    runner = unittest.TextTestRunner()
+    runner.run(suite)

src/workprover/utils.py

@@ -0,0 +1,51 @@
+import hashlib
+import struct
+import time
+import math
+import sys
+import os
+
+def calculateInitialHash(initialPayload):
+    return hashlib.sha512(initialPayload).digest()
+
+def calculateDoubleHash(data):
+    return hashlib.sha512(hashlib.sha512(data).digest()).digest()
+
+# Length including nonce
+
+def calculateTarget(length, TTL, byteDifficulty, lengthExtension):
+    adjustedLength = length + lengthExtension
+    timeEquivalent = TTL * adjustedLength / 2 ** 16
+
+    difficulty = byteDifficulty * (adjustedLength + timeEquivalent)
+
+    return 2 ** 64 / difficulty
+
+def checkProof(nonce, initialHash, target):
+    proof = nonce + initialHash
+    trial, = struct.unpack(">Q", calculateDoubleHash(proof)[: 8])
+
+    return trial <= target
+
+def checkWorkSufficient(payload, byteDifficulty, lengthExtension):
+    expiryTime, = struct.unpack(">Q", payload[8: 16])
+    minimumTTL = max(300, expiryTime - int(time.time()))
+
+    nonce = payload[: 8]
+    initialHash = calculateInitialHash(payload[8: ])
+
+    target = calculateTarget(len(payload), minimumTTL, byteDifficulty, lengthExtension)
+
+    return checkProof(nonce, initialHash, target)
+
+def estimateMaximumIterationsCount(target, probability):
+    coefficient = -math.log(1 - probability)
+    difficulty = 2. ** 64 / target
+
+    return int(coefficient * difficulty + 255) / 256 * 256
+
+if hasattr(sys, "winver"):
+    getTimePoint = time.clock
+else:
+    def getTimePoint():
+        return os.times()[4]