A3

A3/python/filegen/filegen.py

@@ -0,0 +1,64 @@
+#!/bin/python3
+
+import argparse
+import hashlib
+import os
+import shutil
+import struct
+
+
+def gen_cascade_file(sourcefile, targetfile, cascade_file, blocksize):
+    with open(sourcefile, 'rb') as src:
+        # Place entire file in memory :)
+        data = src.read()
+        fullsize = len(data)
+        fullhash = hashlib.sha256(data).digest()
+
+    with open(cascade_file, 'wb') as dst:
+        # Header part
+        dst.write(bytes('CASCADE1', 'ascii')) # Magic signature
+        dst.write(struct.pack('!Q', 0)) # Reserved
+        dst.write(struct.pack('!Q', fullsize)) # File length
+        dst.write(struct.pack('!Q', blocksize)) # Block size
+        dst.write(fullhash)
+
+        with open(sourcefile, 'rb') as src:
+            while True:
+                data = src.read(blocksize)
+                if not data:
+                    break
+                dst.write(hashlib.sha256(data).digest())
+
+    if not os.path.exists(targetfile):
+        shutil.copy(sourcefile, targetfile)
+
+blocksizes = [
+    (1024, '1kib'), 
+    (10240, '10kib'), 
+    (102400, '100kib'), 
+    (1048576, '1mib'), 
+    (10485760, '10mib')
+]
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser()
+    parser.add_argument("source", help="The file to generate the cascade file for")
+    args = parser.parse_args()
+
+    sourcefile = os.path.abspath(args.source)
+    if not os.path.isfile(sourcefile):
+        print(f"Source file not found: {sourcefile}")
+        exit(1)
+
+    for bs in blocksizes:
+        basename, ext = os.path.splitext(sourcefile)
+        targetfile = f"{basename}.{bs[1]}{ext}"
+        cascade_file = f"{targetfile}.cascade"
+        if os.path.isfile(targetfile):
+            print(f"File already exists, deleting: {targetfile}")
+            os.unlink(targetfile)
+
+        print(f"Generating file: {targetfile}")
+        gen_cascade_file(sourcefile, targetfile, cascade_file, bs[0])
+
+    print("Done!")

A3/python/peer/peer.py

@@ -0,0 +1,435 @@
+#!/bin/python3
+
+import argparse
+import os
+import hashlib
+import struct
+import math
+import random
+import socket
+import time
+import socketserver
+import threading
+from typing import Any, List, Union
+
+HASH_LENGTH=32
+
+# Helper method to mask network package fragmentation
+def readbytes(s, count) -> bytes:
+    res = bytearray()
+    while count > 0:
+        msg = s.recv(count)
+        if not msg:
+            raise Exception('Server did not respond')
+        res.extend(msg)
+        count -= len(msg)
+
+    return bytes(res)
+
+
+class CascadeBlock(object):
+    def __init__(self, index: int, offset: int, length: int, hash: bytes) -> None:
+        self.index = index
+        self.offset = offset
+        self.length = length
+        self.hash = hash
+        if len(self.hash) != HASH_LENGTH:
+            raise Exception(f'Hash length should be {HASH_LENGTH} but was {len(self.hash)} (offset: {self.offset})')
+        self.completed = False
+
+class CascadeFile(object):
+    def __init__(self, path: str, destination: str = None) -> None:
+        self.destination = destination
+        with open(path, 'rb') as f:
+            self.cascadehash = hashlib.sha256(f.read()).digest()
+
+        with open(path, 'rb') as f:
+            self.header = f.read(64)
+            if bytes('CASCADE1', 'ascii') != self.header[:8]:
+                raise Exception(f'Signature in file header is invalid: {path}')
+            self.targetsize = struct.unpack('!Q', self.header[16:24])[0]
+            self.blocksize = struct.unpack('!Q', self.header[24:32])[0]
+            self.targethash = self.header[32:64]
+            self.trailblocksize = self.targetsize % self.blocksize
+            if self.trailblocksize == 0: # In case the file size is evenly divisible with the block size
+                self.trailblocksize = self.blocksize 
+                
+            blockcount = math.ceil(self.targetsize /  self.blocksize)
+
+            self.blocks = []
+            for n in range(blockcount):
+                hash = f.read(HASH_LENGTH)
+                if not hash:
+                    raise Exception(f'Incorrect number of hashes in file: {path}, got {n}, but expected {blockcount}')
+
+                self.blocks.append(
+                    CascadeBlock(
+                        n,
+                        n * self.blocksize, 
+                        self.trailblocksize if n == blockcount - 1 else self.blocksize,
+                        hash
+                    )
+                )
+
+            if destination is not None:
+                self.prepare_download(destination)
+
+    def prepare_download(self, destination: str) -> None:
+        # Make sure the target exists
+        if not os.path.isfile(destination):
+            with open(destination, 'wb'):
+                pass
+
+        # Check existing blocks for completion
+        with open(destination, 'rb') as f:
+            for n in range(len(self.blocks)):
+                size = self.blocksize if n != len(self.blocks) - 1 else self.trailblocksize
+                data = f.read(size)
+                if not data:
+                    break
+                if len(data) != size:
+                    break
+                if hashlib.sha256(data).digest() == self.blocks[n].hash:
+                    self.blocks[n].completed = True
+
+        # Create a queue of missing blocks
+        self.queue = list([x for x in self.blocks if not x.completed])
+
+
+class Peer(object):
+    def __init__(self, ip: str, port: int, timestamp: int, good: bool):
+        self.ip = ip 
+        self.port = port
+        self.timestamp = timestamp
+        self.good = good
+
+    def download_block(self, cascadehash, blockno, blocksize) -> bytes:
+        req = bytearray(bytes('CASCADE1', 'ascii'))
+        req.extend(struct.pack('!Q', 0))
+        req.extend(struct.pack('!Q', 0))
+        req.extend(struct.pack('!Q', blockno))
+        req.extend(cascadehash)
+
+        with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
+            s.connect((self.ip, self.port))
+            s.sendall(req)
+            data = s.recv(9)
+            size = struct.unpack('!Q', data[1:9])[0]
+
+            if data[0] == 0:
+                if size != blocksize:
+                    raise Exception(f'The reported block size was {size} but {blocksize} was expected')
+                return readbytes(s, size)
+            elif data[0] == 1:
+                msg = readbytes(s, size).decode('utf-8')
+                raise Exception(f'Client does not have file: {msg}')
+            elif data[0] == 2:
+                msg = readbytes(s, size).decode('utf-8')
+                print(f'Client does not have block {blockno}: {msg}')
+                return None
+            elif data[0] == 3:
+                msg = readbytes(s, size).decode('utf-8')
+                raise Exception(f'Client reported blockno was out-of-bounds: {msg}')
+            elif data[0] == 4:
+                msg = readbytes(s, size).decode('utf-8')
+                raise Exception(f'Client reported invalid request: {msg}')
+            else:
+                raise Exception(f'Client gave unsupported error code: {data[0]}')
+
+
+class Tracker(object):
+    def __init__(self, ip: str, port: int):
+        self.ip = ip
+        self.port = port
+    
+    def list(self, hash: bytes, ip: Union[bytes, str], port: int) -> List[Peer]:
+        return self.send_to_server(self.build_request(1, hash, ip, port))
+
+    def subscribe(self, hash: bytes, ip: Union[bytes, str], port: int) -> List[Peer]:
+        return self.send_to_server(self.build_request(2, hash, ip, port))
+
+    def build_request(self, command: int, hash: bytes, ip: Union[bytes, str], port: int) -> bytes:
+        if isinstance(ip, bytes) or isinstance(ip, bytearray):
+            ipbytes = ip
+        else:
+            ipbytes = bytes(map(int, ip.split('.')))
+
+        if len(ipbytes) != 4:
+            raise Exception('Incorrect IP address?')
+
+        req = bytearray(bytes('CASC', 'ascii'))
+        req.extend(struct.pack('!I', 1))
+        req.extend(struct.pack('!I', command))
+        req.extend(struct.pack('!I', len(hash) + 4 + 2))
+        req.extend(hash)
+        req.extend(ipbytes)
+        req.extend(struct.pack('!H', port))
+
+        return req
+
+
+    def unparse_peer(self, data: bytes) -> Peer:
+        return Peer(
+            '.'.join([str(x) for x in data[0:4]]), 
+            struct.unpack('!H', data[4:6])[0], 
+            struct.unpack('!I', data[6:10])[0], 
+            True if data[10] == 1 else False
+        )
+
+    def send_to_server(self, request: bytes) -> List[Peer]:
+        with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
+            s.connect((self.ip, self.port))
+            s.sendall(request)
+            data = s.recv(5)
+            if not data:
+                raise Exception('Server did not respond')
+            if len(data) != 5:
+                raise Exception('Network protocol error')
+
+            size = struct.unpack('!I', data[1:5])[0]
+            if size > 1024 * 1024:
+                raise Exception(f'Too big server response: {size}')
+            if data[0] != 0:
+                msg = readbytes(s, size).decode('utf-8')
+                raise Exception(f'Tracker gave error: {msg}')
+            else:
+                if size % 12 != 0:
+                    raise Exception('Tracker gave a peer list with a size not a modulo of two')
+                
+                blob = readbytes(s, size)
+                peers = size // 12
+                return list([self.unparse_peer(blob[x*12:(x+1)*12]) for x in range(peers)])
+
+
+class CascadePeerServe(socketserver.StreamRequestHandler):
+    activefiles = {}
+    activefileslock = threading.Lock()
+    HEADER_LENGTH = 8+16+8+HASH_LENGTH
+
+    def handle(self) -> None:
+        while True:
+            try:
+                header = self.request.recv(self.HEADER_LENGTH)
+            except:
+                return
+
+            if header is None:
+                return
+                
+            if len(header) != self.HEADER_LENGTH:
+                self.reporterror(4, f'Invalid header length, got {len(header)} but expected {self.HEADER_LENGTH}')
+                return
+            
+            if header[:8] != bytes('CASCADE1', 'ascii'):
+                self.reporterror(4, f'Invalid header, should start with "CASCADE1", got {header[:8].hex()}')
+                return
+
+            blockno = struct.unpack('!Q', header[24:32])[0]
+            hash = header[32:64]
+
+            file = None
+            with self.activefileslock:
+                if hash in self.activefiles:
+                    file = self.activefiles[hash]
+
+            if file is None:
+                self.reporterror(1, f'Not serving file with hash: {hash.hex()}')
+                return
+
+            if blockno >= len(file.blocks):
+                self.reporterror(3, f'File has {len(file.blocks)} blocks, but {blockno} was requested')
+                return
+
+            block = file.blocks[blockno]
+            if not block.completed:
+                self.reporterror(2, f'{blockno} is not currently held by this peer')
+                continue
+
+            with open(file.destination, 'rb') as f:
+                if f.seek(block.offset) != block.offset:
+                    self.reporterror(2, f'{blockno} is not currently held by this peer (corrupt state)')
+                    return
+
+                data = f.read(block.length)
+                if len(data) != block.length:
+                    self.reporterror(2, f'{blockno} is not currently held by this peer (corrupt state)')
+                    return
+
+                resp = bytearray()
+                resp.extend(struct.pack('!B', 0))
+                resp.extend(struct.pack('!Q', block.length))
+                resp.extend(data)
+
+                self.request.sendall(resp)
+
+    def reporterror(self, code: int, msg: str) -> None:
+        msgdata = bytes(msg, 'utf-8')
+        data = bytearray(struct.pack('!B', code))
+        data.extend(struct.pack('!Q', len(msgdata)))
+        data.extend(msgdata)
+
+        self.request.sendall(data)
+
+class P2PServer(object):
+    def __init__(self, tracker, ip, port) -> None:
+        self.tracker = tracker
+        self.ip = ip
+        self.ipbytes = bytes(map(int, selfaddr.split('.')))
+        self.port = port
+        self.stopped = False
+        self.refreshsemaphore = threading.Semaphore(0)
+        self.peers = {}
+
+        self.serverthread = threading.Thread(target=self.run_peer_server, daemon=True)
+        self.refreshthread = threading.Thread(target=self.run_peer_subscribe, daemon=True)
+        self.serverthread.start()
+        self.refreshthread.start()
+
+    def resubscribe(self) -> None:
+        self.refreshsemaphore.release()
+
+    def join(self) -> None:
+        self.serverthread.join()
+
+    def stop(self) -> None:
+        self.stopped = True
+        self.server.shutdown()
+        self.refreshsemaphore.release()
+        self.refreshthread.join()
+        self.serverthread.join()
+
+    def run_peer_server(self) -> None:
+        print(f"Running peer server on {self.ip}:{self.port}")
+        with socketserver.ThreadingTCPServer((self.ip, self.port), CascadePeerServe) as server:
+            self.server = server
+            server.serve_forever(poll_interval=10)
+
+    def run_peer_subscribe(self) -> None:
+        while not self.stopped:
+            with CascadePeerServe.activefileslock:
+                hashes = list(CascadePeerServe.activefiles)
+
+            for h in hashes:
+                try:
+                    self.peers[h] = self.tracker.subscribe(h, self.ipbytes, self.port)
+                except Exception as e:
+                    print(f"Tracker register failed: {e}")
+
+            self.refreshsemaphore.acquire(timeout=60*10)
+
+def run_peer_download(tracker: Tracker, source: str, localip: str, localport: int, server:P2PServer = None, output:str = None, randomseq:bool =True) -> None:
+    if not os.path.isfile(source):
+        print("File not found: {args.source}")
+        exit(1)
+
+    if output is None:
+        output = os.path.splitext(source)[0]
+
+    print(f"Preparing download of {source} to {output}")
+    file = CascadeFile(source, output)
+
+    if len(file.queue) != 0:
+        print(f"Download will require {len(file.queue)} blocks of size {file.blocksize}")
+
+    with CascadePeerServe.activefileslock:
+        CascadePeerServe.activefiles[file.cascadehash] = file
+
+    if server is not None:
+        server.resubscribe() # Trigger server subscription with new file
+
+    peers = []
+    last_peer_update = 0
+    while len(file.queue) > 0:        
+
+        # Ensure we have peers
+        while len(peers) == 0 or time.time() - last_peer_update > 60*5:
+            if time.time() - last_peer_update < 30:
+                print(f'Throttling peer update; wait for 30s')
+                time.sleep(30)
+
+            try:
+                peers = tracker.list(file.cascadehash, localip, localport)
+            except Exception as e:
+                print(f"Tracker error: {e}")
+            finally:
+                last_peer_update = time.time()
+
+
+            if len(peers) == 0:
+                print(f"We have no peers, sleeping 10s before trying again")
+                time.sleep(10)
+            else:
+                print(f"We got {len(peers)} peer{'s' if len(peers) == 1 else ''}")
+
+        # Pick a block
+        blockid = 0 if not randomseq else random.randrange(0, len(file.queue))
+        peerid = 0 if not randomseq else random.randrange(0, len(peers))
+        block = file.queue[blockid]
+        peer = peers[peerid]
+
+        # Grab it
+        print(f"Attempting to fetch block {block.index} from {peer.ip}:{peer.port}")
+        print(f"Attempting to fetch block with hash {file.cascadehash}")
+        try:
+            data = peer.download_block(file.cascadehash, block.index, block.length)
+            if data is None:
+                raise Exception('Peer did not have the requested block')
+
+            datahash = hashlib.sha256(data).digest()                
+            if datahash != block.hash:
+                print(f"Invalid hash for block {block.index} from {peer.ip}:{peer.port}. Got {datahash.hex()} but expected {block.hash.hex()}")
+                raise Exception('Downloaded block was incorrect')
+
+            with open(output, 'r+b') as f:
+                f.seek(block.offset)
+                f.write(data)
+
+            block.completed = True
+            file.queue.remove(block)
+            print(f"Retrieved block {block.index}")
+
+        except Exception as e:
+            peers.remove(peer)
+            print(f"Download failure ignoring peer. {e}")
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser()
+    parser.add_argument("source", help="The cascade source file(s) with information about the download")
+    parser.add_argument("tracker", help="The tracker ip and port, eg: localhost:8888", default="127.0.0.1:8888")
+    parser.add_argument("self", help="The address to report serving files from, e.g.: 1.2.3.4:5555", default="127.0.0.1:7777")
+    parser.add_argument("-o", "--output", help="The target output file(s)", required=False)
+    parser.add_argument("-r", "--random", help="Download blocks in random order from random peers", type=bool, required=False, default=True)
+    parser.add_argument("-c", "--clientonly", help="Flag to set client-only mode (i.e. no serving)", type=bool, required=False, default=False)
+    args = parser.parse_args()
+
+    tracker = Tracker(args.tracker.split(':')[0], int(args.tracker.split(':')[1]))
+    selfaddr, selfport = args.self.split(':')    
+    selfport = int(selfport)
+
+    server = None
+    if not args.clientonly:
+        server = P2PServer(tracker, selfaddr, selfport)
+
+    source_files = args.source.split(os.pathsep)
+    if args.output is None:
+        target_files = []
+    else:
+        target_files = args.output.split(os.pathsep)
+
+    for ix, f in zip(range(len(source_files)), source_files):
+        target = None
+        if ix < len(target_files):
+            target = target_files[ix]
+        run_peer_download(tracker, f, selfaddr, selfport, server, target, args.random)
+
+    if args.clientonly:
+        print("Download complete in client mode, stopping")
+    else:
+        print("Download complete serving forever ...")
+        server.join()
+
+
+
+
+

A3/python/tracker/config.json

@@ -0,0 +1,14 @@
+{
+    "port": 8888,
+    "ban-private": false,
+    "allowedhashes": [
+        "713a203b7e89753a8893f7d452e8bcc19de65024595f50ddf7899f1da9d95fff",
+        "e29fcee1b3fbd186ae430f39e66661d7e0aec549998d63df438b51736fcf7a8e",
+        "28bccac30019632135bed1e273d259b3c31ad135d92b9db907f120a1c801b40c",
+        "729578b33120e7c9ba3c8a88cc6820cda3162adf8ce5294888ed62b435c5da7f",
+        "81b831d167d74a11d4a95fd11c41e895edbec56d79e5a29b162217a805b539a6"
+    ],
+    "good-ips": [
+        "127.0.0.1"
+    ]
+}

A3/python/tracker/tracker.py

@@ -0,0 +1,193 @@
+#!/bin/python3
+
+import os
+import argparse
+import struct
+import socketserver
+import json
+import time
+import random
+import threading
+import ipaddress
+
+HEADER_LENGTH=16
+HASH_LENGTH=32
+CMD_LENGTH=HASH_LENGTH + 4 + 2
+IP_LENGTH=4
+PORT_LENGTH=2
+MAX_PEERS_REPORTED=20
+MAX_PEER_AGE_SECONDS=1800
+
+def is_good_client(ip, goods):
+    return len([x for x in goods if ip == x]) > 0
+
+class TrackerServer(socketserver.StreamRequestHandler):
+    active_clients = {}
+    lock = threading.Lock()
+    last_cleanup = 0
+
+    def handle(self):
+        # self.request is the TCP socket connected to the client
+        header = self.request.recv(HEADER_LENGTH)
+        if len(header) != HEADER_LENGTH:
+            self.respond_error(f'Header must be at least {HEADER_LENGTH} bytes, got {len(header)}')
+            return
+        
+        if header[:4] != bytes('CASC', 'ascii'):
+            self.respond_error(f'Header must start with CASC ({bytes("CASC", "ascii").hex()}), got: {header[:4].hex()}')
+            return
+
+        protocol_version = struct.unpack('!I', header[4:8])[0]
+        command = struct.unpack('!I', header[8:12])[0]
+        datalen = struct.unpack('!I', header[12:16])[0]
+        if protocol_version != 1:
+            self.respond_error(f'Protocol version must be 1, got: {protocol_version}')
+            return
+
+        if command == 1 or command == 2:
+            if datalen != CMD_LENGTH:
+                self.respond_error(f'Data for command=1 must be of length {CMD_LENGTH}, got {datalen}')
+                return
+                
+            data = self.request.recv(CMD_LENGTH)
+            if len(data) != CMD_LENGTH:
+                self.respond_error(f'Data from socket had length {len(data)}, expected {CMD_LENGTH}')
+                return
+
+            hash = data[:32]
+            hashhex = hash.hex()
+            ipportkey = data[32:].hex()
+
+            with self.lock:
+                hashfound = hashhex in self.active_clients
+
+            if not hashfound:
+                self.respond_error(f"The supplied hash '{hashhex}' is not tracked by this tracker")
+                return
+
+            if command == 2:
+                # For local testing you may need to remove this check
+#                if data[32:36] == b'\0\0\0\0':
+#                    self.respond_error(f'The IP {({".".join([str(x) for x in data[32:36]])})} is not supported')
+#                    return
+
+                if self.banprivateips and ipaddress.IPv4Address(data[32:36]).is_private:
+                    self.respond_error(f'The IP reported to the tracker ({".".join([str(x) for x in data[32:36]])}) appears to be a private IP')
+                    return
+
+                # Avoid peers registering as good peers without approval
+                if is_good_client(data[32:36], self.goodips):
+                    if str(ipaddress.IPv4Address(data[32:36])) == self.client_address[0]:
+                        print("Registering a good client")
+                    else:
+                        self.respond_error(f'The IP reported to the tracker ({".".join([str(x) for x in data[32:36]])}) is a reserved IP')
+                        return
+                else:
+                    print("Not a good client")
+
+                with self.lock:
+                    self.active_clients[hashhex][ipportkey] = int(time.time())
+
+            self.report_clients(hash.hex(), ipportkey)
+
+        else:
+            self.respond_error(f'Only commands (list=1, subscribe=2) supported, got: {command}')
+            return
+
+    def report_clients(self, hashhex, selfipport=None):
+        now = int(time.time())
+
+        with self.lock:
+            # Perform cleanup, if required
+            if self.last_cleanup == 0:
+                self.last_cleanup = now
+            elif now - self.last_cleanup > (MAX_PEER_AGE_SECONDS * 2):
+                self.last_cleanup = now
+                for h in self.active_clients:
+                    for x in list([n for n in h if now - n > MAX_PEER_AGE_SECONDS]):
+                        del h[x]
+
+            # Build list of peers
+            d = self.active_clients[hashhex]
+            peers = list([(
+                bytes.fromhex(x)[:IP_LENGTH], # Ip is tupple item 0
+                bytes.fromhex(x)[IP_LENGTH:IP_LENGTH+PORT_LENGTH], # Port is tupple item 1
+                d[x], # Timestamp is tupple item 2
+                is_good_client(bytes.fromhex(x)[:IP_LENGTH], self.goodips) # Good flag is tupple item 3
+                ) for x in d if now - d[x] < MAX_PEER_AGE_SECONDS and x != selfipport])
+
+        # Random order
+        random.shuffle(peers)
+        peers.sort(key=lambda x: x[3] != 1) # Keep good ones at top
+
+        # Build response
+        result = bytearray()
+        for n,ix in zip(peers, range(MAX_PEERS_REPORTED)):
+            result.extend(n[0]) # ip
+            result.extend(n[1]) # port
+            result.extend(struct.pack('!l', n[2])) #timestamp
+            result.extend(struct.pack('!B', 1 if n[3] else 0)) # Good flag
+            result.extend(struct.pack('!B', 0)) # reserved
+
+        header = bytearray()
+        header.extend(struct.pack('!B', 0))
+        header.extend(struct.pack('!I', len(result)))
+        header.extend(result)
+
+        self.request.sendall(header)
+
+    def respond_error(self, msg):
+        msgdata = bytes(msg, 'utf-8')
+        data = bytearray(struct.pack('!B', 1))
+        data.extend(struct.pack('!I', len(msgdata)))
+        data.extend(msgdata)
+
+        self.request.sendall(data)
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser()
+    parser.add_argument("config", help="The configuration file")
+    args = parser.parse_args()
+
+    if not os.path.isfile(args.config):
+        print(f"Config file not found: {args.config}")
+
+    with open(args.config) as jf:
+        config = json.load(jf)
+    if not "port" in config:
+        print("Config is missing port")
+        exit(1)
+    if not "allowedhashes" in config:
+        print("Config is missing allowedhashes")
+        exit(1)
+
+    if len(config["allowedhashes"]) <= 0:
+        print("Need at least one allowed hash")
+        exit(1)
+
+    if not "good-ips" in config:
+        config["good-ips"] = []
+
+    HOST, PORT = "0.0.0.0", int(config['port'])
+    hashes = list(bytes.fromhex(x) for x in config['allowedhashes'])
+    invalids = [x for x in hashes if len(x) != 32]
+    if len(invalids) > 0:
+        print(f"Invalid hashes: {', '.join([x.hex() for x in invalids])}")
+        exit(1)
+
+    goodips = list([bytes(map(int, ip.split('.'))) for ip in config["good-ips"]])
+    invalids = [x for x in goodips if len(x) != 4]
+    if len(invalids) > 0:
+        print(f"Invalid IPs: {', '.join(['.'.join([str(x) for x in ip]) for ip in invalids])}")
+        exit(1)
+
+    TrackerServer.active_clients = dict(zip([x.hex() for x in hashes], [{} for x in range(len(hashes))]))
+    TrackerServer.goodips = goodips
+    TrackerServer.banprivateips = False
+    if 'ban-private' in config:
+        TrackerServer.banprivateips = config['ban-private']
+
+    with socketserver.ThreadingTCPServer((HOST, PORT), TrackerServer) as server:
+        server.serve_forever()
+

A3/src/Makefile

@@ -0,0 +1,29 @@
+GCC=gcc -O3 -g -Wall -Wextra -pedantic -std=gnu11
+LD_FLAGS= -lpthread
+
+all: peer name_server cascade
+
+rebuild: clean all
+
+csapp.o: csapp.c csapp.h
+	$(GCC) -c $< -o $@
+
+common.o: common.c common.h
+	$(GCC) -c $< -o $@
+
+cascade: cascade.c cascade.h common.o csapp.o sha256.o
+	$(GCC) $< *.o -o $@ $(LD_FLAGS)
+
+name_server: name_server.c name_server.h common.o csapp.o
+	$(CC) $(CFLAGS) $< *.o -o $@ $(LD_FLAGS)
+
+sha256.o : sha256.c sha256.h
+	$(CC) $(CFLAGS) -c $< -o $@
+
+zip: ../src.zip
+
+../src.zip: clean
+	cd .. && zip -r src.zip src/Makefile src/*.c src/*.h src/tests/*
+
+clean:
+	rm -rf *.o peer name_server cascade sha256 vgcore*

A3/src/cascade.c

@@ -0,0 +1,450 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <netdb.h>
+#include <sys/socket.h>
+#include <arpa/inet.h>
+#include <endian.h>
+#include <string.h>
+
+#include "./cascade.h"
+#include "./sha256.h"
+
+char tracker_ip[IP_LEN];
+char tracker_port[PORT_LEN];
+char my_ip[IP_LEN];
+char my_port[PORT_LEN];
+
+struct csc_file *casc_file;
+csc_block_t** queue;
+csc_peer_t* peers;
+
+void free_resources()
+{
+    free(queue);
+    free(peers);
+    csc_free_file(casc_file);
+}
+
+unsigned char* get_file_sha(const char* sourcefile, csc_file_t* res, char* hash, int size)
+{
+    int n;
+    int casc_file_size;
+
+    FILE* fp = fopen(sourcefile, "rb");
+    if (fp == 0)
+    {
+        printf("Failed to open source: %s\n", sourcefile);
+        return NULL;
+    }
+    
+    fseek(fp, 0L, SEEK_END);
+    casc_file_size = ftell(fp);
+    fseek(fp, 0L, SEEK_SET);
+
+    char buffer[casc_file_size];
+    fread(buffer, casc_file_size, 1, fp); 
+    fclose(fp);
+    
+    SHA256_CTX shactx;
+    unsigned char shabuffer[size];
+    sha256_init(&shactx);
+    sha256_update(&shactx, buffer, casc_file_size);
+    sha256_final(&shactx, &shabuffer);
+    
+    for (int i=0; i<size; i++)
+    {
+        hash[i] = shabuffer[i];
+    }
+}
+
+void download_only_peer(char *cascade_file)
+{
+    printf("Managing download only for: %s\n", cascade_file);    
+    if (access(cascade_file, F_OK ) != 0 ) 
+    {
+        fprintf(stderr, ">> File %s does not exist\n", cascade_file);
+        exit(EXIT_FAILURE);
+    }
+
+    char output_file[strlen(cascade_file)]; 
+    memcpy(output_file, cascade_file, strlen(cascade_file));
+    char* r = strstr(cascade_file, "cascade");
+    int cutoff = r - cascade_file ;
+    output_file[cutoff-1] = '\0';
+    printf("Downloading to: %s\n", output_file);
+       
+    casc_file = csc_parse_file(cascade_file, output_file);
+    
+    /*
+    TODO Create a list of missing blocks
+    */
+    
+    /*
+    TODO Compute the hash of the cascade file
+    HINT: Do not implement hashing from scratch. Use the provided 'get_file_sha' function
+    */
+
+    int peercount = 0;
+    while (peercount == 0)
+    {
+        peercount = get_peers_list(&peers, hash_buf, tracker_ip, tracker_port);
+        if (peercount == 0)
+        {
+            printf("No peers were found. Will try again in %d seconds\n", PEER_REQUEST_DELAY);
+            fflush(stdout);
+            sleep(PEER_REQUEST_DELAY);
+        }
+        else
+        {
+            printf("Found %d peer(s)\n", peercount);
+        }
+    }
+    
+    csc_peer_t peer = (peers[0]);
+    // Get a good peer if one is available
+    for (int i=0; i<peercount; i++)
+    {
+        if (peers[i].good)
+        {
+            peer = peers[i];
+        }
+    }
+
+    for (int i=0; i<uncomp_count; i++)
+    {
+        get_block(queue[i], peer, hash_buf, output_file);
+    }
+    
+    free_resources();
+}
+
+int count_occurences(char string[], char c)
+{
+    int i=0;
+    int count=0;
+    for(i=0; i<strlen(string); i++)  
+    {
+        if(string[i] == c)
+        {
+            count++;
+        }
+    }
+    return count;
+}
+
+// Adapted from: https://stackoverflow.com/a/35452093/
+uint8_t* hex_to_bytes(const char* string) {
+
+    if(string == NULL) 
+       return NULL;
+
+    size_t slength = strlen(string);
+    if((slength % 2) != 0) // must be even
+       return NULL;
+
+    size_t dlength = slength / 2;
+
+    uint8_t* data = malloc(dlength);
+    memset(data, 0, dlength);
+
+    size_t index = 0;
+    while (index < slength) {
+        char c = string[index];
+        int value = 0;
+        if(c >= '0' && c <= '9')
+          value = (c - '0');
+        else if (c >= 'A' && c <= 'F') 
+          value = (10 + (c - 'A'));
+        else if (c >= 'a' && c <= 'f')
+          value = (10 + (c - 'a'));
+        else {
+          free(data);
+          return NULL;
+        }
+
+        data[(index/2)] += value << (((index + 1) % 2) * 4);
+
+        index++;
+    }
+
+    return data;
+}
+
+/*
+ * Parses a cascade file, given the sourcepath input and destination, which may or may not exist.
+ * Returns a pointer to a datastructure describing the file, or NULL if the file could not be parsed
+ */
+csc_file_t* csc_parse_file(const char* sourcefile, const char* destination)
+{
+    FILE* fp = fopen(sourcefile, "rb");
+    if (fp == 0)
+    {
+        printf("Failed to open source: %s\n", sourcefile);
+        return NULL;
+    }
+
+    const int FILE_HEADER_SIZE = 8+8+8+8+32;
+
+    char header[FILE_HEADER_SIZE];
+    if (fread(header, 1, FILE_HEADER_SIZE, fp) != FILE_HEADER_SIZE)
+    {
+        printf("Failed to read magic 8 bytes header from file\n");
+        fclose(fp);
+        return NULL;
+    }
+
+    if (memcmp(header, "CASCADE1", 8) != 0)
+    {
+        printf("File does not contain magic 8 bytes in header\n");
+        fclose(fp);
+        return NULL;
+    }
+
+    csc_file_t* casc_file_data = (csc_file_t*)malloc(sizeof(csc_file_t));
+
+    /*
+    TODO Parse the cascade file and store the data in an appropriate data structure    
+    
+    HINT Use the definition of the 'csc_file' struct in cascade.h, as well as the 
+    assignment handout for guidance on what each attribute is and where it is stored 
+    in the files header/body.
+    */
+    
+    fclose(fp);
+
+    fp = fopen(destination, "a+w");
+    if (fp == NULL)
+    {
+        printf("Failed to open destination file %s\n", destination);
+        csc_free_file(casc_file_data);
+        return NULL;
+    }
+    
+    void* buffer = malloc(casc_file_data->blocksize);
+    if (buffer == NULL)
+    {
+        printf("No block buffer asigned: %d\n", casc_file_data->blocksize);
+        csc_free_file(casc_file_data);
+        fclose(fp);
+        return NULL;
+    }
+    
+    SHA256_CTX shactx;
+    for(unsigned long long i = 0; i < casc_file_data->blockcount; i++)
+    {
+        char shabuffer[SHA256_HASH_SIZE];
+        unsigned long long size = casc_file_data->blocks[i].length;        
+        if (fread(buffer, size, 1, fp) != 1)
+        {
+            break;
+        }
+
+        sha256_init(&shactx);
+        sha256_update(&shactx, buffer, size);
+        sha256_final(&shactx, &shabuffer);
+        
+        /*
+        TODO Compare the hashes taken from the Cascade file with those of the local data 
+        file and keep a record of any missing blocks
+        
+        HINT The code above takes a hash of each block of data in the local file in turn 
+        and stores it in the 'shabuffer' variable. You can compare then compare 'shabuffer'
+        directly to the hashes of each block you have hopefully already assigned as part 
+        of the 'casc_file_data' struct
+        */
+    }
+    fclose(fp);
+
+    return casc_file_data;
+}
+
+/*
+ * Releases the memory allocated by a file datastructure
+ */
+void csc_free_file(csc_file_t* file)
+{
+    free(file->blocks);
+    file->blocks = NULL;
+    free(file);
+}
+
+size_t readbytes(int sock, void* buffer, size_t count)
+{
+    size_t remaining = count;
+    while(remaining > 0)
+    {
+        size_t read = recv(sock, buffer, remaining, NULL);
+        if (read == 0)
+            return 0;
+        buffer += read;
+        remaining -= read;
+    }
+
+    return count;
+}
+
+void get_block(csc_block_t* block, csc_peer_t peer, unsigned char* hash, char* output_file)
+{
+    printf("Attempting to get block %d from %s:%s for %s\n", block->index, peer.ip, peer.port, output_file);
+    
+    rio_t rio;    
+    char rio_buf[MAX_LINE];
+    int peer_socket;
+    
+    /*
+    TODO Request a block from a peer
+    */
+    
+    FILE* fp = fopen(output_file, "rb+");
+    if (fp == 0)
+    {
+        printf("Failed to open destination: %s\n", output_file);
+        Close(peer_socket);
+        return NULL;
+    }
+
+    /*
+    TODO Write the block into the data file
+    */
+    
+    printf("Got block %d. Wrote from %d to %d\n", block->index, block->offset, block->offset+write_count-1);
+    Close(peer_socket);
+    fclose(fp);
+}
+
+int get_peers_list(csc_peer_t** peers, unsigned char* hash, char* tracker_ip, char* tracker_port, char* my_ip, char* my_port)
+{
+    rio_t rio;    
+    char rio_buf[MAX_LINE];
+    int tracker_socket;
+    
+    /*
+    TODO Setup a connection to the tracker
+    */
+
+    struct RequestHeader request_header;
+    strncpy(request_header.protocol, "CASC", 4);
+    request_header.version = htonl(1);
+    request_header.command = htonl(1);
+    request_header.length = htonl(BODY_SIZE);
+    memcpy(rio_buf, &request_header, HEADER_SIZE);
+
+    /*
+    TODO Complete the peer list request and 
+    HINT The header has been provided above as a guide
+    */
+    
+    Rio_writen(tracker_socket, rio_buf, MESSAGE_SIZE);
+
+    Rio_readnb(&rio, rio_buf, MAXLINE);
+    
+    char reply_header[REPLY_HEADER_SIZE];
+    memcpy(reply_header, rio_buf, REPLY_HEADER_SIZE);  
+
+    uint32_t msglen = ntohl(*(uint32_t*)&reply_header[1]);
+    if (msglen == 0)
+    {
+        Close(tracker_socket);
+        return 0;        
+    }
+    
+    if (reply_header[0] != 0) 
+    {
+        char* error_buf = malloc(msglen + 1);
+        if (error_buf == NULL)
+        {
+            printf("Tracker error %d and out-of-memory reading error\n", reply_header[0]);
+            Close(tracker_socket);
+            return NULL;
+        }
+        memset(error_buf, 0, msglen + 1);
+        memcpy(reply_header, error_buf, msglen);
+        printf("Tracker gave error: %d - %s\n", reply_header[0], error_buf);
+        free(error_buf);
+        Close(tracker_socket);
+        return NULL;
+    }
+
+    if (msglen % 12 != 0)
+    {
+        printf("LIST response from tracker was length %llu but should be evenly divisible by 12\n", msglen);
+        Close(tracker_socket);
+        return NULL;
+    }
+    
+    /*
+    TODO Parse the body of the response to get a list of peers
+    
+    HINT Some of the later provided code expects the peers to be stored in the ''peers' variable, which 
+    is an array of 'csc_peer's, as defined in cascade.h
+    */
+
+    Close(tracker_socket);
+    return peercount;
+}
+
+int main(int argc, char **argv) 
+{
+    if (argc != MAIN_ARGNUM + 1) 
+    {
+        fprintf(stderr, "Usage: %s <cascade file(s)> <tracker server ip> <tracker server port> <peer ip> <peer port>.\n", argv[0]);
+        exit(EXIT_FAILURE);
+    } 
+    else if (!is_valid_ip(argv[2])) 
+    {
+        fprintf(stderr, ">> Invalid tracker IP: %s\n", argv[2]);
+        exit(EXIT_FAILURE);
+    } 
+    else if (!is_valid_port(argv[3])) 
+    {
+        fprintf(stderr, ">> Invalid tracker port: %s\n", argv[3]);
+        exit(EXIT_FAILURE);
+    } 
+    else if (!is_valid_ip(argv[4])) 
+    {
+        fprintf(stderr, ">> Invalid peer IP: %s\n", argv[4]);
+        exit(EXIT_FAILURE);
+    } 
+    else if (!is_valid_port(argv[5])) 
+    {
+        fprintf(stderr, ">> Invalid peer port: %s\n", argv[5]);
+        exit(EXIT_FAILURE);
+    }
+
+    snprintf(tracker_ip,   IP_LEN,   argv[2]);
+    snprintf(tracker_port, PORT_LEN, argv[3]);
+    snprintf(my_ip,   IP_LEN,   argv[4]);
+    snprintf(my_port, PORT_LEN, argv[5]);
+    
+    char cas_str[strlen(argv[1])];
+    snprintf(cas_str, strlen(argv[1])+1, argv[1]);
+    char delim[] = ":";
+
+    int casc_count = count_occurences(argv[1], ':') + 1;
+    char *cascade_files[casc_count];
+
+    char *ptr = strtok(cas_str, delim);
+    int i = 0;
+
+    while (ptr != NULL)
+    {
+        if (strstr(ptr, ".cascade") != NULL)
+        {
+            cascade_files[i++] = ptr;
+            ptr = strtok(NULL, delim);
+        }
+        else
+        {
+            printf("Abort on %s\n", ptr);   
+            fprintf(stderr, ">> Invalid cascade file: %s\n", ptr);
+            exit(EXIT_FAILURE);
+        }
+    }
+
+    for (int j=0; j<casc_count; j++)
+    {
+        download_only_peer(cascade_files[j]);
+    }
+
+    exit(EXIT_SUCCESS);
+}

A3/src/cascade.h

@@ -0,0 +1,115 @@
+
+#pragma once
+#include "common.h"
+
+#ifndef CASCADE_H
+#define CASCADE_H
+#define MAIN_ARGNUM                 5   // number of command line arguments to main().
+#define BODY_SIZE                   38
+#define HEADER_SIZE                 16
+#define MESSAGE_SIZE                54
+#define REPLY_HEADER_SIZE           5
+#define PEER_REQUEST_DELAY          10
+#define PEER_REQUEST_HEADER_SIZE    64
+#define PEER_RESPONSE_HEADER_SIZE   9
+#define MAX_LINE                    128
+
+
+struct RequestHeader
+{
+  char protocol[4];
+  unsigned int version; 
+  unsigned int command; 
+  unsigned int length; 
+};
+
+struct RequestBody
+{
+  char hash[32];
+  struct in_addr ip;
+  unsigned short port;
+};
+
+struct ClientRequest
+{
+    char protocol[8];
+    char reserved[12];
+    uint64_t block_num;
+    char hash[32];
+};
+
+struct ClientResponseHeader
+{
+    char error[1];
+    uint64_t length; 
+};
+
+#include <stdint.h>
+
+typedef struct csc_hashdata { uint8_t x[32]; } csc_hashdata_t;
+
+typedef struct csc_ipport { 
+    uint32_t ip; 
+    uint16_t port;
+} csc_ipport_t;
+
+typedef struct csc_block {
+    uint64_t index;             // The index of this block in the data file
+    uint64_t offset;            // Number of bytes the start of this block is offset from the start of the file
+    uint64_t length;            // Number of bytes within this block
+    uint8_t completed;          // Flag of if this block is present in local file system or not
+    csc_hashdata_t hash;        // Hash of this blocks bytes
+} csc_block_t;
+
+typedef struct csc_file {
+    uint64_t targetsize;        // Size of completed data file
+    uint64_t blocksize;         // Size of individual blocks data is divided into
+    csc_hashdata_t targethash;  // Hash of complete data file
+    uint64_t trailblocksize;    // Size of last block. Will differ from standard block size if data does not evenly divide amoungst blocks
+    uint64_t blockcount;        // Number of blocks data is divided into
+    csc_block_t* blocks;        // Pointer to array of all blocks
+} csc_file_t;
+
+typedef struct csc_peer { 
+    char ip[16];                // IP of a peer
+    char port[8];               // Port of a peer
+    uint32_t lastseen;          // Timestamp of last time Tracker saw this Peer
+    uint8_t good;               // Flag for if this is 'Good' peer. e.g. Always provides valid responses according to protocol
+} csc_peer_t;
+
+typedef struct csc_server {
+} csc_server_t;
+
+/*
+ * Parses a hex-string and returns the bytes corresponding to the value
+ */
+uint8_t* hex_to_bytes(const char* string);
+
+/*
+ * Parses a cascade file, given the sourcepath input and destination, which may or may not exist.
+ * Returns a pointer to a datastructure describing the file, or NULL if the file could not be parsed
+ */
+csc_file_t* csc_parse_file(const char* sourcefile, const char* destination);
+
+/*
+ * Releases the memory allocated by a file datastructure
+ */
+void csc_free_file(csc_file_t* sourcefile);
+
+/*
+ * Attempts to get a list of peers from the tracker.
+ * The peers should contain a pre-allocated set of memory that can hold at least peercount elements.
+ * If the function is successful, the return code is zero and the value of peercount has been updated to contain the number of peers.
+ * If the function fails, the return code is non-zero
+ */
+int csc_get_peers(csc_ipport_t tracker, csc_hashdata_t cascadehash, csc_ipport_t localaddress, uint8_t subscribe, uint32_t* peercount, csc_peer_t* peers);
+
+/*
+ * Downloads a block of data from a client.
+ * The supplied buffer should be at least large enough to contain blocklength-bytes.
+ * If the function is successful, the return code is zero, and the buffer contains data of the size requested by blocklength.
+ * If the function fails, the return code is non-zero, and will reflect the peer statuscode (if given).
+ */
+int csc_download_block(csc_ipport_t client, csc_hashdata_t cascadehash, uint64_t blockno, uint64_t blocklength, void* buffer);
+
+#endif

A3/src/common.c

@@ -0,0 +1,97 @@
+#include "common.h"
+
+/*
+ * below two utility functions are for parsing user input.
+ * YOU ONLY NEED A WORKING UNDERSTANDING OF parse_command,
+ * and how it stores parsed arguments (see common.h).
+ */
+command_t parse_command(char  *user_input,
+                        args_t args) {
+
+  for (int i = 0; i < MAX_USER_ARGNUM; i++)
+    args[i] = NULL;
+
+  char *saveptr;
+  char *command_str = strtok_r(user_input, " \n", &saveptr);
+  if (command_str == NULL) return ERROR;
+
+  if (string_equal(command_str, "/msg")) {             // if command_str is /msg, recipient username
+    args[0] = strtok_r(NULL, " \n",   &saveptr);       // and actual message will be stored in
+    args[1] = strtok_r(NULL, "\n\x0", &saveptr);       // first two arguments, respectively.
+
+    if (args[0] == NULL || args[1] == NULL) return ERROR;
+    else return MSG;
+  }
+
+  unsigned int num_args = extract_args(saveptr, args); // args now contains arguments to command_str.
+
+  return string_equal(command_str, "/login")  && num_args == 4 ? LOGIN
+       : string_equal(command_str, "/lookup") && num_args <= 1 ? LOOKUP
+       : string_equal(command_str, "/show")   && num_args <= 1 ? SHOW
+       : string_equal(command_str, "/logout") && num_args == 0 ? LOGOUT
+       : string_equal(command_str, "/exit")   && num_args == 0 ? EXIT
+       : ERROR;
+}
+
+/*
+ * auxiliary function used by parse_command.
+ */
+inline size_t extract_args(char  *input,
+                           args_t args) {
+
+  char *saveptr;
+  size_t num_args = 0;
+  while ((input = strtok_r(input, " \n\x0", &saveptr)) != NULL) { // and still tokens left to extract
+
+    num_args++;
+    if (num_args > MAX_USER_ARGNUM)
+      break;
+
+    args[num_args-1] = input;
+    input = NULL;     // strtok needs to be called with a null pointer to keep searching.
+  }
+  return num_args;
+}
+
+
+/*
+ * returns 1 if ip_string is a valid IP address; else 0
+ */
+int is_valid_ip(char *ip_string) {
+  int ip[4];
+  int num_parsed = sscanf(ip_string, "%d.%d.%d.%d", ip+0, ip+1, ip+2, ip+3);
+  printf("ip_string: a%sa\n", ip_string);
+
+  if (num_parsed < 0) {
+    fprintf(stderr, "sscanf() error: %s\n", strerror(errno));
+    exit(EXIT_FAILURE);
+  } 
+
+  else if (num_parsed != 4)
+    return string_equal(ip_string, "localhost");
+
+  for (int i = 0; i < 4; i++)
+    if (ip[i] > 255 || ip[i] < 0)
+      return 0;
+
+  return 1;
+}
+
+
+/*
+ * returns 1 if port_string is a valid port number; else 0
+ */
+int is_valid_port(char *port_string) {
+  int port;
+  int num_parsed = sscanf(port_string, "%d", &port);
+
+  if (num_parsed < 0) {
+    fprintf(stderr, "sscanf() error: %s\n", strerror(errno));
+    exit(EXIT_FAILURE);
+  }
+
+  else if (num_parsed != 1 || port < 0 || port > 65535)
+    return 0;
+
+  return 1;
+}

A3/src/common.h

@@ -0,0 +1,67 @@
+#pragma once
+#include <stdlib.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <string.h>
+#include <assert.h>
+#include "csapp.h"
+
+/*
+ * add macros and function declarations which should be 
+ * common between the name server and peer programs in this file.
+ */
+
+#define USERNAME_LEN       32   // max length of a valid username.
+#define MAX_LINE           128  // max length of a line of user input.
+#define MAX_USER_ARGNUM 4       // max number of arguments to peer commands.
+
+#define IP_LEN             16
+#define PORT_LEN           8
+
+/* slightly less awkward string equality check */
+#define string_equal(x, y) (strncmp((x), (y), strlen(y)) == 0)
+
+/* enum type used to represent client commands */
+typedef enum command_t {
+  LOGIN,
+  LOGOUT,
+  EXIT,
+  LOOKUP,
+  MSG,
+  SHOW,
+  ERROR
+} command_t;
+
+/* string array type of size MAX_USER_ARGNUM used to hold arguments to a command */
+typedef char *args_t[MAX_USER_ARGNUM];
+
+
+/*
+ * given "input", a newline- or NULL-terminated line of
+ * user input containing command, followed by 0 or more
+ * space-separated arguments, and "args", an args_t array:
+ * - parses command and stores arguments sequentially in args.
+ * - returns a command_t code representing the command.
+ * - on an invalid number of arguments, ERROR is returned.
+ *
+ *   example: if command is "/login anders topsecret 130.225.245.178 1337", then
+ *   args is the array ["anders", "topsecret", "130.225.245.178", "1337"],
+ *   and the function returns LOGIN.
+ *   (if command is a /msg, then recipient username and actual message stored in args[0..1]).
+ */
+command_t parse_command(char *input,
+                        args_t args);
+
+/*
+ * extract arguments from a line of user input and store in args.
+ */
+size_t extract_args(char *input,
+                    args_t args);
+
+
+/*
+ * naive validity checks of IP addresses and port numbers given as strings,
+ * eg. at command line. both return zero on invalid IP/port, else non-zero.
+ */
+int is_valid_ip(char *ip_string);
+int is_valid_port(char *port_string);

A3/src/csapp.h

@@ -0,0 +1,199 @@
+/*
+ * csapp.h - prototypes and definitions for the CS:APP3e book
+ */
+/* $begin csapp.h */
+#ifndef __CSAPP_H__
+#define __CSAPP_H__
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdarg.h>
+#include <unistd.h>
+#include <string.h>
+#include <ctype.h>
+#include <setjmp.h>
+#include <signal.h>
+#include <dirent.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <sys/mman.h>
+#include <errno.h>
+#include <math.h>
+#include <pthread.h>
+#include <semaphore.h>
+#include <sys/socket.h>
+#include <netdb.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+
+/* Default file permissions are DEF_MODE & ~DEF_UMASK */
+/* $begin createmasks */
+#define DEF_MODE   S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP|S_IROTH|S_IWOTH
+#define DEF_UMASK  S_IWGRP|S_IWOTH
+/* $end createmasks */
+
+/* Simplifies calls to bind(), connect(), and accept() */
+/* $begin sockaddrdef */
+typedef struct sockaddr SA;
+/* $end sockaddrdef */
+
+/* Persistent state for the robust I/O (Rio) package */
+/* $begin rio_t */
+#define RIO_BUFSIZE 8192
+typedef struct {
+    int rio_fd;                /* Descriptor for this internal buf */
+    int rio_cnt;               /* Unread bytes in internal buf */
+    char *rio_bufptr;          /* Next unread byte in internal buf */
+    char rio_buf[RIO_BUFSIZE]; /* Internal buffer */
+} rio_t;
+/* $end rio_t */
+
+/* External variables */
+extern int h_errno;    /* Defined by BIND for DNS errors */ 
+extern char **environ; /* Defined by libc */
+
+/* Misc constants */
+#define	MAXLINE	 8192  /* Max text line length */
+#define MAXBUF   8192  /* Max I/O buffer size */
+#define LISTENQ  1024  /* Second argument to listen() */
+
+/* Our own error-handling functions */
+void unix_error(char *msg);
+void posix_error(int code, char *msg);
+void dns_error(char *msg);
+void gai_error(int code, char *msg);
+void app_error(char *msg);
+
+/* Process control wrappers */
+pid_t Fork(void);
+void Execve(const char *filename, char *const argv[], char *const envp[]);
+pid_t Wait(int *status);
+pid_t Waitpid(pid_t pid, int *iptr, int options);
+void Kill(pid_t pid, int signum);
+unsigned int Sleep(unsigned int secs);
+void Pause(void);
+unsigned int Alarm(unsigned int seconds);
+void Setpgid(pid_t pid, pid_t pgid);
+pid_t Getpgrp();
+
+/* Signal wrappers */
+typedef void handler_t(int);
+handler_t *Signal(int signum, handler_t *handler);
+void Sigprocmask(int how, const sigset_t *set, sigset_t *oldset);
+void Sigemptyset(sigset_t *set);
+void Sigfillset(sigset_t *set);
+void Sigaddset(sigset_t *set, int signum);
+void Sigdelset(sigset_t *set, int signum);
+int Sigismember(const sigset_t *set, int signum);
+int Sigsuspend(const sigset_t *set);
+
+/* Sio (Signal-safe I/O) routines */
+ssize_t sio_puts(char s[]);
+ssize_t sio_putl(long v);
+void sio_error(char s[]);
+
+/* Sio wrappers */
+ssize_t Sio_puts(char s[]);
+ssize_t Sio_putl(long v);
+void Sio_error(char s[]);
+
+/* Unix I/O wrappers */
+int Open(const char *pathname, int flags, mode_t mode);
+ssize_t Read(int fd, void *buf, size_t count);
+ssize_t Write(int fd, const void *buf, size_t count);
+off_t Lseek(int fildes, off_t offset, int whence);
+void Close(int fd);
+int Select(int  n, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, 
+	   struct timeval *timeout);
+int Dup2(int fd1, int fd2);
+void Stat(const char *filename, struct stat *buf);
+void Fstat(int fd, struct stat *buf) ;
+
+/* Directory wrappers */
+DIR *Opendir(const char *name);
+struct dirent *Readdir(DIR *dirp);
+int Closedir(DIR *dirp);
+
+/* Memory mapping wrappers */
+void *Mmap(void *addr, size_t len, int prot, int flags, int fd, off_t offset);
+void Munmap(void *start, size_t length);
+
+/* Standard I/O wrappers */
+void Fclose(FILE *fp);
+FILE *Fdopen(int fd, const char *type);
+char *Fgets(char *ptr, int n, FILE *stream);
+FILE *Fopen(const char *filename, const char *mode);
+void Fputs(const char *ptr, FILE *stream);
+size_t Fread(void *ptr, size_t size, size_t nmemb, FILE *stream);
+void Fwrite(const void *ptr, size_t size, size_t nmemb, FILE *stream);
+
+/* Dynamic storage allocation wrappers */
+void *Malloc(size_t size);
+void *Realloc(void *ptr, size_t size);
+void *Calloc(size_t nmemb, size_t size);
+void Free(void *ptr);
+
+/* Sockets interface wrappers */
+int Socket(int domain, int type, int protocol);
+void Setsockopt(int s, int level, int optname, const void *optval, int optlen);
+void Bind(int sockfd, struct sockaddr *my_addr, int addrlen);
+void Listen(int s, int backlog);
+int Accept(int s, struct sockaddr *addr, socklen_t *addrlen);
+void Connect(int sockfd, struct sockaddr *serv_addr, int addrlen);
+
+/* Protocol independent wrappers */
+void Getaddrinfo(const char *node, const char *service, 
+                 const struct addrinfo *hints, struct addrinfo **res);
+void Getnameinfo(const struct sockaddr *sa, socklen_t salen, char *host, 
+                 size_t hostlen, char *serv, size_t servlen, int flags);
+void Freeaddrinfo(struct addrinfo *res);
+void Inet_ntop(int af, const void *src, char *dst, socklen_t size);
+void Inet_pton(int af, const char *src, void *dst); 
+
+/* DNS wrappers */
+struct hostent *Gethostbyname(const char *name);
+struct hostent *Gethostbyaddr(const char *addr, int len, int type);
+
+/* Pthreads thread control wrappers */
+void Pthread_create(pthread_t *tidp, pthread_attr_t *attrp, 
+		    void * (*routine)(void *), void *argp);
+void Pthread_join(pthread_t tid, void **thread_return);
+void Pthread_cancel(pthread_t tid);
+void Pthread_detach(pthread_t tid);
+void Pthread_exit(void *retval);
+pthread_t Pthread_self(void);
+void Pthread_once(pthread_once_t *once_control, void (*init_function)());
+
+/* POSIX semaphore wrappers */
+void Sem_init(sem_t *sem, int pshared, unsigned int value);
+void P(sem_t *sem);
+void V(sem_t *sem);
+
+/* Rio (Robust I/O) package */
+ssize_t rio_readn(int fd, void *usrbuf, size_t n);
+ssize_t rio_writen(int fd, void *usrbuf, size_t n);
+void rio_readinitb(rio_t *rp, int fd); 
+ssize_t	rio_readnb(rio_t *rp, void *usrbuf, size_t n);
+ssize_t	rio_readlineb(rio_t *rp, void *usrbuf, size_t maxlen);
+
+/* Wrappers for Rio package */
+ssize_t Rio_readn(int fd, void *usrbuf, size_t n);
+void Rio_writen(int fd, void *usrbuf, size_t n);
+void Rio_readinitb(rio_t *rp, int fd); 
+ssize_t Rio_readnb(rio_t *rp, void *usrbuf, size_t n);
+ssize_t Rio_readlineb(rio_t *rp, void *usrbuf, size_t maxlen);
+
+/* Reentrant protocol-independent client/server helpers */
+int open_clientfd(char *hostname, char *port);
+int open_listenfd(char *port);
+
+/* Wrappers for reentrant protocol-independent client/server helpers */
+int Open_clientfd(char *hostname, char *port);
+int Open_listenfd(char *port);
+
+
+#endif /* __CSAPP_H__ */
+/* $end csapp.h */

A3/src/sha256.c

@@ -0,0 +1,480 @@
+/*-
+ * Copyright (c) 2001-2003 Allan Saddi <allan@saddi.com>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY ALLAN SADDI AND HIS CONTRIBUTORS ``AS IS''
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL ALLAN SADDI OR HIS CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ * $Id: sha256.c 680 2003-07-25 21:57:49Z asaddi $
+ */
+
+/*
+ * Define WORDS_BIGENDIAN if compiling on a big-endian architecture.
+ *
+ * Define SHA256_TEST to test the implementation using the NIST's
+ * sample messages. The output should be:
+ *
+ *   ba7816bf 8f01cfea 414140de 5dae2223 b00361a3 96177a9c b410ff61 f20015ad
+ *   248d6a61 d20638b8 e5c02693 0c3e6039 a33ce459 64ff2167 f6ecedd4 19db06c1
+ *   cdc76e5c 9914fb92 81a1c7e2 84d73e67 f1809a48 a497200e 046d39cc c7112cd0
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "clamav-config.h"
+#endif /* HAVE_CONFIG_H */
+
+#if HAVE_INTTYPES_H
+# include <inttypes.h>
+#else
+# if HAVE_STDINT_H
+#  include <stdint.h>
+# endif
+#endif
+
+#include <string.h>
+
+#include "sha256.h"
+
+#ifndef lint
+static const char rcsid[] =
+	"$Id: sha256.c 680 2003-07-25 21:57:49Z asaddi $";
+#endif /* !lint */
+
+#define ROTL(x, n) (((x) << (n)) | ((x) >> (32 - (n))))
+#define ROTR(x, n) (((x) >> (n)) | ((x) << (32 - (n))))
+
+#define Ch(x, y, z) ((z) ^ ((x) & ((y) ^ (z))))
+#define Maj(x, y, z) (((x) & ((y) | (z))) | ((y) & (z)))
+#define SIGMA0(x) (ROTR((x), 2) ^ ROTR((x), 13) ^ ROTR((x), 22))
+#define SIGMA1(x) (ROTR((x), 6) ^ ROTR((x), 11) ^ ROTR((x), 25))
+#define sigma0(x) (ROTR((x), 7) ^ ROTR((x), 18) ^ ((x) >> 3))
+#define sigma1(x) (ROTR((x), 17) ^ ROTR((x), 19) ^ ((x) >> 10))
+
+#define DO_ROUND() { \
+  t1 = h + SIGMA1(e) + Ch(e, f, g) + *(Kp++) + *(W++); \
+  t2 = SIGMA0(a) + Maj(a, b, c); \
+  h = g; \
+  g = f; \
+  f = e; \
+  e = d + t1; \
+  d = c; \
+  c = b; \
+  b = a; \
+  a = t1 + t2; \
+}
+
+static const uint32_t K[64] = {
+  0x428a2f98L, 0x71374491L, 0xb5c0fbcfL, 0xe9b5dba5L,
+  0x3956c25bL, 0x59f111f1L, 0x923f82a4L, 0xab1c5ed5L,
+  0xd807aa98L, 0x12835b01L, 0x243185beL, 0x550c7dc3L,
+  0x72be5d74L, 0x80deb1feL, 0x9bdc06a7L, 0xc19bf174L,
+  0xe49b69c1L, 0xefbe4786L, 0x0fc19dc6L, 0x240ca1ccL,
+  0x2de92c6fL, 0x4a7484aaL, 0x5cb0a9dcL, 0x76f988daL,
+  0x983e5152L, 0xa831c66dL, 0xb00327c8L, 0xbf597fc7L,
+  0xc6e00bf3L, 0xd5a79147L, 0x06ca6351L, 0x14292967L,
+  0x27b70a85L, 0x2e1b2138L, 0x4d2c6dfcL, 0x53380d13L,
+  0x650a7354L, 0x766a0abbL, 0x81c2c92eL, 0x92722c85L,
+  0xa2bfe8a1L, 0xa81a664bL, 0xc24b8b70L, 0xc76c51a3L,
+  0xd192e819L, 0xd6990624L, 0xf40e3585L, 0x106aa070L,
+  0x19a4c116L, 0x1e376c08L, 0x2748774cL, 0x34b0bcb5L,
+  0x391c0cb3L, 0x4ed8aa4aL, 0x5b9cca4fL, 0x682e6ff3L,
+  0x748f82eeL, 0x78a5636fL, 0x84c87814L, 0x8cc70208L,
+  0x90befffaL, 0xa4506cebL, 0xbef9a3f7L, 0xc67178f2L
+};
+
+#ifndef RUNTIME_ENDIAN
+
+#if WORDS_BIGENDIAN == 1 
+
+#define BYTESWAP(x) (x)
+#define BYTESWAP64(x) (x)
+
+#else /* WORDS_BIGENDIAN */
+
+#define BYTESWAP(x) ((ROTR((x), 8) & 0xff00ff00L) | \
+		     (ROTL((x), 8) & 0x00ff00ffL))
+#define BYTESWAP64(x) _byteswap64(x)
+
+static inline uint64_t _byteswap64(uint64_t x)
+{
+  uint32_t a = x >> 32;
+  uint32_t b = (uint32_t) x;
+  return ((uint64_t) BYTESWAP(b) << 32) | (uint64_t) BYTESWAP(a);
+}
+
+#endif /* WORDS_BIGENDIAN */
+
+#else /* !RUNTIME_ENDIAN */
+
+#define BYTESWAP(x) _byteswap(sc->littleEndian, x)
+#define BYTESWAP64(x) _byteswap64(sc->littleEndian, x)
+
+#define _BYTESWAP(x) ((ROTR((x), 8) & 0xff00ff00L) | \
+		      (ROTL((x), 8) & 0x00ff00ffL))
+#define _BYTESWAP64(x) __byteswap64(x)
+
+static inline uint64_t __byteswap64(uint64_t x)
+{
+  uint32_t a = x >> 32;
+  uint32_t b = (uint32_t) x;
+  return ((uint64_t) _BYTESWAP(b) << 32) | (uint64_t) _BYTESWAP(a);
+}
+
+static inline uint32_t _byteswap(int littleEndian, uint32_t x)
+{
+  if (!littleEndian)
+    return x;
+  else
+    return _BYTESWAP(x);
+}
+
+static inline uint64_t _byteswap64(int littleEndian, uint64_t x)
+{
+  if (!littleEndian)
+    return x;
+  else
+    return _BYTESWAP64(x);
+}
+
+static inline void setEndian(int *littleEndianp)
+{
+  union {
+    uint32_t w;
+    uint8_t b[4];
+  } endian;
+
+  endian.w = 1L;
+  *littleEndianp = endian.b[0] != 0;
+}
+
+#endif /* !RUNTIME_ENDIAN */
+
+static const uint8_t padding[64] = {
+  0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
+};
+
+void
+sha256_init (SHA256_CTX *sc)
+{
+#ifdef RUNTIME_ENDIAN
+  setEndian (&sc->littleEndian);
+#endif /* RUNTIME_ENDIAN */
+
+  sc->totalLength = 0LL;
+  sc->hash[0] = 0x6a09e667L;
+  sc->hash[1] = 0xbb67ae85L;
+  sc->hash[2] = 0x3c6ef372L;
+  sc->hash[3] = 0xa54ff53aL;
+  sc->hash[4] = 0x510e527fL;
+  sc->hash[5] = 0x9b05688cL;
+  sc->hash[6] = 0x1f83d9abL;
+  sc->hash[7] = 0x5be0cd19L;
+  sc->bufferLength = 0L;
+}
+
+static void
+burnStack (int size)
+{
+  char buf[128];
+
+  memset (buf, 0, sizeof (buf));
+  size -= sizeof (buf);
+  if (size > 0)
+    burnStack (size);
+}
+
+static void
+SHA256Guts (SHA256_CTX *sc, const uint32_t *cbuf)
+{
+  uint32_t buf[64];
+  uint32_t *W, *W2, *W7, *W15, *W16;
+  uint32_t a, b, c, d, e, f, g, h;
+  uint32_t t1, t2;
+  const uint32_t *Kp;
+  int i;
+
+  W = buf;
+
+  for (i = 15; i >= 0; i--) {
+    *(W++) = BYTESWAP(*cbuf);
+    cbuf++;
+  }
+
+  W16 = &buf[0];
+  W15 = &buf[1];
+  W7 = &buf[9];
+  W2 = &buf[14];
+
+  for (i = 47; i >= 0; i--) {
+    *(W++) = sigma1(*W2) + *(W7++) + sigma0(*W15) + *(W16++);
+    W2++;
+    W15++;
+  }
+
+  a = sc->hash[0];
+  b = sc->hash[1];
+  c = sc->hash[2];
+  d = sc->hash[3];
+  e = sc->hash[4];
+  f = sc->hash[5];
+  g = sc->hash[6];
+  h = sc->hash[7];
+
+  Kp = K;
+  W = buf;
+
+#ifndef SHA256_UNROLL
+#define SHA256_UNROLL 4
+#endif /* !SHA256_UNROLL */
+
+#if SHA256_UNROLL == 1
+  for (i = 63; i >= 0; i--)
+    DO_ROUND();
+#elif SHA256_UNROLL == 2
+  for (i = 31; i >= 0; i--) {
+    DO_ROUND(); DO_ROUND();
+  }
+#elif SHA256_UNROLL == 4
+  for (i = 15; i >= 0; i--) {
+    DO_ROUND(); DO_ROUND(); DO_ROUND(); DO_ROUND();
+  }
+#elif SHA256_UNROLL == 8
+  for (i = 7; i >= 0; i--) {
+    DO_ROUND(); DO_ROUND(); DO_ROUND(); DO_ROUND();
+    DO_ROUND(); DO_ROUND(); DO_ROUND(); DO_ROUND();
+  }
+#elif SHA256_UNROLL == 16
+  for (i = 3; i >= 0; i--) {
+    DO_ROUND(); DO_ROUND(); DO_ROUND(); DO_ROUND();
+    DO_ROUND(); DO_ROUND(); DO_ROUND(); DO_ROUND();
+    DO_ROUND(); DO_ROUND(); DO_ROUND(); DO_ROUND();
+    DO_ROUND(); DO_ROUND(); DO_ROUND(); DO_ROUND();
+  }
+#elif SHA256_UNROLL == 32
+  for (i = 1; i >= 0; i--) {
+    DO_ROUND(); DO_ROUND(); DO_ROUND(); DO_ROUND();
+    DO_ROUND(); DO_ROUND(); DO_ROUND(); DO_ROUND();
+    DO_ROUND(); DO_ROUND(); DO_ROUND(); DO_ROUND();
+    DO_ROUND(); DO_ROUND(); DO_ROUND(); DO_ROUND();
+    DO_ROUND(); DO_ROUND(); DO_ROUND(); DO_ROUND();
+    DO_ROUND(); DO_ROUND(); DO_ROUND(); DO_ROUND();
+    DO_ROUND(); DO_ROUND(); DO_ROUND(); DO_ROUND();
+    DO_ROUND(); DO_ROUND(); DO_ROUND(); DO_ROUND();
+  }
+#elif SHA256_UNROLL == 64
+  DO_ROUND(); DO_ROUND(); DO_ROUND(); DO_ROUND();
+  DO_ROUND(); DO_ROUND(); DO_ROUND(); DO_ROUND();
+  DO_ROUND(); DO_ROUND(); DO_ROUND(); DO_ROUND();
+  DO_ROUND(); DO_ROUND(); DO_ROUND(); DO_ROUND();
+  DO_ROUND(); DO_ROUND(); DO_ROUND(); DO_ROUND();
+  DO_ROUND(); DO_ROUND(); DO_ROUND(); DO_ROUND();
+  DO_ROUND(); DO_ROUND(); DO_ROUND(); DO_ROUND();
+  DO_ROUND(); DO_ROUND(); DO_ROUND(); DO_ROUND();
+  DO_ROUND(); DO_ROUND(); DO_ROUND(); DO_ROUND();
+  DO_ROUND(); DO_ROUND(); DO_ROUND(); DO_ROUND();
+  DO_ROUND(); DO_ROUND(); DO_ROUND(); DO_ROUND();
+  DO_ROUND(); DO_ROUND(); DO_ROUND(); DO_ROUND();
+  DO_ROUND(); DO_ROUND(); DO_ROUND(); DO_ROUND();
+  DO_ROUND(); DO_ROUND(); DO_ROUND(); DO_ROUND();
+  DO_ROUND(); DO_ROUND(); DO_ROUND(); DO_ROUND();
+  DO_ROUND(); DO_ROUND(); DO_ROUND(); DO_ROUND();
+#else
+#error "SHA256_UNROLL must be 1, 2, 4, 8, 16, 32, or 64!"
+#endif
+
+  sc->hash[0] += a;
+  sc->hash[1] += b;
+  sc->hash[2] += c;
+  sc->hash[3] += d;
+  sc->hash[4] += e;
+  sc->hash[5] += f;
+  sc->hash[6] += g;
+  sc->hash[7] += h;
+}
+
+void
+sha256_update (SHA256_CTX *sc, const void *vdata, uint32_t len)
+{
+  const uint8_t *data = vdata;
+  uint32_t bufferBytesLeft;
+  uint32_t bytesToCopy;
+  int needBurn = 0;
+#ifdef SHA256_FAST_COPY
+  if (sc->bufferLength) {
+    bufferBytesLeft = 64L - sc->bufferLength;
+
+    bytesToCopy = bufferBytesLeft;
+    if (bytesToCopy > len)
+      bytesToCopy = len;
+
+    memcpy (&sc->buffer.bytes[sc->bufferLength], data, bytesToCopy);
+
+    sc->totalLength += bytesToCopy * 8L;
+
+    sc->bufferLength += bytesToCopy;
+    data += bytesToCopy;
+    len -= bytesToCopy;
+
+    if (sc->bufferLength == 64L) {
+      SHA256Guts (sc, sc->buffer.words);
+      needBurn = 1;
+      sc->bufferLength = 0L;
+    }
+  }
+
+  while (len > 63L) {
+    sc->totalLength += 512L;
+
+    SHA256Guts (sc, data);
+    needBurn = 1;
+
+    data += 64L;
+    len -= 64L;
+  }
+
+  if (len) {
+    memcpy (&sc->buffer.bytes[sc->bufferLength], data, len);
+
+    sc->totalLength += len * 8L;
+
+    sc->bufferLength += len;
+  }
+#else /* SHA256_FAST_COPY */
+  while (len) {
+    bufferBytesLeft = 64L - sc->bufferLength;
+
+    bytesToCopy = bufferBytesLeft;
+    if (bytesToCopy > len)
+      bytesToCopy = len;
+
+    memcpy (&sc->buffer.bytes[sc->bufferLength], data, bytesToCopy);
+
+    sc->totalLength += bytesToCopy * 8L;
+
+    sc->bufferLength += bytesToCopy;
+    data += bytesToCopy;
+    len -= bytesToCopy;
+
+    if (sc->bufferLength == 64L) {
+      SHA256Guts (sc, sc->buffer.words);
+      needBurn = 1;
+      sc->bufferLength = 0L;
+    }
+  }
+#endif /* SHA256_FAST_COPY */
+
+  if (needBurn)
+    burnStack (sizeof (uint32_t[74]) + sizeof (uint32_t *[6]) + sizeof (int));
+}
+
+void
+sha256_final (SHA256_CTX *sc, uint8_t hash[SHA256_HASH_SIZE])
+{
+  uint32_t bytesToPad;
+  uint64_t lengthPad;
+  int i;
+
+  bytesToPad = 120L - sc->bufferLength;
+  if (bytesToPad > 64L)
+    bytesToPad -= 64L;
+
+  lengthPad = BYTESWAP64(sc->totalLength);
+
+  sha256_update (sc, padding, bytesToPad);
+  sha256_update (sc, &lengthPad, 8L);
+
+  if (hash) {
+    for (i = 0; i < SHA256_HASH_WORDS; i++) {
+#ifdef SHA256_FAST_COPY
+      *((uint32_t *) hash) = BYTESWAP(sc->hash[i]);
+#else /* SHA256_FAST_COPY */
+      hash[0] = (uint8_t) (sc->hash[i] >> 24);
+      hash[1] = (uint8_t) (sc->hash[i] >> 16);
+      hash[2] = (uint8_t) (sc->hash[i] >> 8);
+      hash[3] = (uint8_t) sc->hash[i];
+#endif /* SHA256_FAST_COPY */
+      hash += 4;
+    }
+  }
+}
+
+#ifdef SHA256_TEST
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+int
+main (int argc, char *argv[])
+{
+  SHA256_CTX foo;
+  uint8_t hash[SHA256_HASH_SIZE];
+  char buf[1000];
+  int i;
+
+  sha256_init (&foo);
+  sha256_update (&foo, "abc", 3);
+  sha256_final (&foo, hash);
+
+  for (i = 0; i < SHA256_HASH_SIZE;) {
+    printf ("%02x", hash[i++]);
+    if (!(i % 4))
+      printf (" ");
+  }
+  printf ("\n");
+
+  sha256_init (&foo);
+  sha256_update (&foo,
+		"abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq",
+		56);
+  sha256_final (&foo, hash);
+
+  for (i = 0; i < SHA256_HASH_SIZE;) {
+    printf ("%02x", hash[i++]);
+    if (!(i % 4))
+      printf (" ");
+  }
+  printf ("\n");
+
+  sha256_init (&foo);
+  memset (buf, 'a', sizeof (buf));
+  for (i = 0; i < 1000; i++)
+    sha256_update (&foo, buf, sizeof (buf));
+  sha256_final (&foo, hash);
+
+  for (i = 0; i < SHA256_HASH_SIZE;) {
+    printf ("%02x", hash[i++]);
+    if (!(i % 4))
+      printf (" ");
+  }
+  printf ("\n");
+
+  exit (0);
+}
+
+#endif /* SHA256_TEST */

A3/src/sha256.h

@@ -0,0 +1,66 @@
+/*-
+ * Copyright (c) 2001-2003 Allan Saddi <allan@saddi.com>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY ALLAN SADDI AND HIS CONTRIBUTORS ``AS IS''
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL ALLAN SADDI OR HIS CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ * $Id: sha256.h 348 2003-02-23 22:12:06Z asaddi $
+ */
+
+#ifndef _SHA256_H
+#define _SHA256_H
+
+#include <stdint.h>
+
+#define SHA256_HASH_SIZE 32
+
+/* Hash size in 32-bit words */
+#define SHA256_HASH_WORDS 8
+
+struct _SHA256Context {
+  uint64_t totalLength;
+  uint32_t hash[SHA256_HASH_WORDS];
+  uint32_t bufferLength;
+  union {
+    uint32_t words[16];
+    uint8_t bytes[64];
+  } buffer;
+#ifdef RUNTIME_ENDIAN
+  int littleEndian;
+#endif /* RUNTIME_ENDIAN */
+};
+
+typedef struct _SHA256Context SHA256_CTX;
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+void sha256_init (SHA256_CTX *sc);
+void sha256_update (SHA256_CTX *sc, const void *data, uint32_t len);
+void sha256_final (SHA256_CTX *sc, uint8_t hash[SHA256_HASH_SIZE]);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* !_SHA256_H */