Multithreaded-HTTP-Server/server.py at main · codejasleen/Multithreaded-HTTP-Server · GitHub

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import socket, threading, queue, os, argparse, time, json, random, string, posixpath
from urllib.parse import unquote
from email.utils import formatdate
from datetime import datetime

#  config
host = "127.0.0.1"
port = 8080
threads = 10
backlog = 50
header_max = 8192
keepalive_timeout = 30
keepalive_max = 100
server_name = "Multi-threaded HTTP Server"
allowed_exts = {"html","txt","png","jpg","jpeg"}

# resolve resources dir safely
try:
    BASE_DIR = os.path.dirname(os.path.abspath(__file__))
except NameError:
    BASE_DIR = os.getcwd()
resources_dir = os.path.join(BASE_DIR, "resources")

# tiny logs
def nowstamp(): return datetime.now().strftime("%Y-%m-%d %H:%M:%S")
def log(x): print(f"[{nowstamp()}] {x}", flush=True)
def tlog(x): print(f"[{nowstamp()}] [{threading.current_thread().name}] {x}", flush=True)

# http helpers
def http_date(): return formatdate(usegmt=True)
def reason(code):
    m = {200:"OK",201:"Created",400:"Bad Request",403:"Forbidden",404:"Not Found",
         405:"Method Not Allowed",411:"Length Required",413:"Payload Too Large",
         415:"Unsupported Media Type",500:"Internal Server Error",503:"Service Unavailable"}
    return m.get(code, "OK")

def send_resp(sock, code, headers=None, body=b""):
    h = {} if headers is None else dict(headers)
    h.setdefault("Date", http_date())
    h.setdefault("Server", server_name)
    if body is not None:
        h["Content-Length"] = str(len(body))
    start = f"HTTP/1.1 {code} {reason(code)}\r\n"
    head = "".join(f"{k}: {v}\r\n" for k,v in h.items())
    sock.sendall(start.encode("ascii") + head.encode("ascii") + b"\r\n" + (body or b""))

def send_err(sock, code, msg="", common=None):
    b = (f"<!doctype html><html><head><meta charset='utf-8'><title>{code} {reason(code)}</title></head>"
         f"<body><h1>{code} {reason(code)}</h1><p>{msg}</p></body></html>").encode("utf-8")
    hh = {"Content-Type":"text/html; charset=utf-8"}
    if common: hh.update(common)
    send_resp(sock, code, hh, b)
    tlog(f"Response: {code} {reason(code)} ({len(b)} bytes transferred)")

# request reading
def read_headers(sock, limit=header_max):
    data = b""
    while b"\r\n\r\n" not in data:
        chunk = sock.recv(1024)
        if not chunk: break
        data += chunk
        if len(data) > limit:
            return None, b""
    if b"\r\n\r\n" not in data:
        return None, b""
    head, leftover = data.split(b"\r\n\r\n", 1)
    return head, leftover

def parse_head(head_bytes):
    try:
        txt = head_bytes.decode("iso-8859-1")
        lines = txt.split("\r\n")
        p0 = lines[0].split()
        if len(p0) != 3: return None
        method, path, ver = p0
        H = {}
        for ln in lines[1:]:
            if not ln.strip(): continue
            if ":" not in ln: return None
            k, v = ln.split(":", 1)
            H[k.strip().lower()] = v.strip()
        return method, path, ver, H
    except:
        return None

def conn_policy(ver, H):
    c = H.get("connection","").lower()
    if ver == "HTTP/1.1":
        return "keep-alive" if c != "close" else "close"
    else:
        return "keep-alive" if c == "keep-alive" else "close"

# security + path helpers
def host_ok(host_header, bind_host, bind_port):
    ok = {f"localhost:{bind_port}", f"127.0.0.1:{bind_port}"}
    if bind_host not in ("0.0.0.0","",None):
        ok.add(f"{bind_host}:{bind_port}")
    return host_header in ok

def decode_and_norm(pth):
    d = unquote(pth or "")
    n = posixpath.normpath(d if d else "/")
    if not n.startswith("/"): n = "/" + n
    return d, n

def looks_bad(decoded_path):
    s = decoded_path.lower()
    if ("\\" in s or s.startswith("//") or "/./" in s or s.endswith("/.")
        or s.startswith("./") or ".." in s):
        return True
    return False

def safe_join(nrm):
    rel = nrm.lstrip("/")
    want = os.path.realpath(os.path.join(resources_dir, rel))
    base = os.path.realpath(resources_dir)
    if not want.startswith(base + os.sep) and want != base:
        return None
    return want

#  handlers
def handle_get(sock, raw_path, common):
    dec, nrm = decode_and_norm(raw_path)
    if looks_bad(dec):
        tlog(f"Security: traversal in path '{dec}' → 403")
        send_err(sock, 403, "Path traversal blocked.", common); return
    if nrm == "/":
        nrm = "/index.html"
    fp = safe_join(nrm)
    if not fp:
        tlog(f"Security: canonicalization escaped resources for '{dec}' → 403")
        send_err(sock, 403, "Forbidden.", common); return
    if not (os.path.exists(fp) and os.path.isfile(fp)):
        send_err(sock, 404, "File not found.", common); return
    ext = os.path.splitext(fp)[1].lstrip(".").lower()
    if ext not in allowed_exts:
        tlog(f"Security: unsupported extension requested ({ext}) → 415")
        send_err(sock, 415, "Only .html, .txt, .png, .jpg/.jpeg allowed.", common); return

    size = os.path.getsize(fp)
    if ext == "html":
        hh = {"Content-Type":"text/html; charset=utf-8"}; hh.update(common)
        with open(fp, "rb") as f: body = f.read()
        send_resp(sock, 200, hh, body)
        tlog(f"Response: 200 OK ({len(body)} bytes transferred)")
        tlog(f"Connection: {common.get('Connection','')}")
    else:
        hh = {"Content-Type":"application/octet-stream",
              "Content-Disposition": f'attachment; filename="{os.path.basename(fp)}"'}
        hh.update(common)
        head = f"HTTP/1.1 200 {reason(200)}\r\n" + "".join(
            f"{k}: {v}\r\n" for k,v in {**hh,"Content-Length":str(size)}.items()
        ) + "\r\n"
        tlog(f"Sending binary file: {os.path.basename(fp)} ({size} bytes)")
        sock.sendall(head.encode("ascii"))
        sent = 0
        with open(fp, "rb") as f:
            while True:
                chunk = f.read(8192)
                if not chunk: break
                sock.sendall(chunk); sent += len(chunk)
        tlog(f"Response: 200 OK ({sent} bytes transferred)")
        tlog(f"Connection: {common.get('Connection','')}")

def handle_post(sock, raw_path, ver, H, leftover, common):
    dec, nrm = decode_and_norm(raw_path)
    tlog(f"POST target: {dec}")
    if nrm != "/upload":
        send_err(sock, 404, "Not Found.", common); return

    ct = H.get("content-type","").split(";")[0].strip().lower()
    if ct != "application/json":
        tlog("Security: wrong Content-Type for POST → 415")
        send_err(sock, 415, "Only application/json accepted.", common); return

    if "content-length" not in H:
        send_err(sock, 411, "Content-Length required.", common); return
    try: L = int(H["content-length"])
    except: L = -1
    if L < 0 or L > 5*1024*1024:
        send_err(sock, 413, "Payload Too Large.", common); return

    tlog(f"POST Content-Length: {L}")

    body = leftover
    while len(body) < L:
        x = sock.recv(min(8192, L - len(body)))
        if not x: break
        body += x

    try:
        json.loads(body.decode("utf-8"))
    except:
        send_err(sock, 400, "Invalid JSON.", common); return

    up = os.path.join(resources_dir, "uploads"); os.makedirs(up, exist_ok=True)
    tstr = time.strftime("%Y%m%d_%H%M%S", time.localtime())
    rid = "".join(random.choice(string.ascii_lowercase+string.digits) for _ in range(4))
    fname = f"upload_{tstr}_{rid}.json"
    with open(os.path.join(up, fname), "wb") as f: f.write(body)

    out = {"status":"success","message":"File created successfully","filepath":f"/uploads/{fname}"}
    jj = json.dumps(out).encode("utf-8")
    hh = {"Content-Type":"application/json"}; hh.update(common)
    send_resp(sock, 201, hh, jj)
    tlog(f"Response: 201 Created ({len(jj)} bytes transferred)")
    tlog(f"Connection: {common.get('Connection','')}")

# per-connection loop
def serve_client(conn, addr, bind_host, bind_port):
    conn.settimeout(keepalive_timeout)
    reqs = 0
    try:
        while True:
            head, rest = read_headers(conn, header_max)
            if head is None: return
            parsed = parse_head(head)
            if not parsed:
                send_err(conn, 400, "Malformed request."); return

            method, path, ver, H = parsed
            tlog(f"Request: {method} {path} {ver}")

            hv = H.get("host")
            if not hv:
                tlog("Host validation: (missing) ✗")
                send_err(conn, 400, "Missing Host header."); return
            if not host_ok(hv, bind_host, bind_port):
                tlog(f"Host validation: {hv} ✗")
                send_err(conn, 403, "Invalid Host header."); return
            tlog(f"Host validation: {hv} ✓")

            policy = conn_policy(ver, H)
            common = {"Connection": policy, "Keep-Alive": f"timeout={keepalive_timeout}, max={keepalive_max}"}

            try:
                if method == "GET":
                    handle_get(conn, path, common)
                elif method == "POST":
                    handle_post(conn, path, ver, H, rest, common)
                else:
                    send_err(conn, 405, "Only GET and POST are allowed.", common)
            except:
                send_err(conn, 500, "Server error.", common); return

            reqs += 1
            if policy != "keep-alive" or reqs >= keepalive_max:
                return
    except socket.timeout:
        tlog("idle timeout")
    except:
        pass
    finally:
        try: conn.close()
        except: pass

# fixed-size ThreadPool
class ThreadPool:
    def __init__(self, n, qmax=100):
        self.q = queue.Queue(maxsize=qmax)
        self.n = n
        self.busy = set()
        self.alive = True
        self.lock = threading.Lock()
        self.workers = []
        for i in range(n):
            t = threading.Thread(target=self.work, name=f"Thread-{i+1}", daemon=True)
            t.start(); self.workers.append(t)
        self.mon = threading.Thread(target=self.watch, name="PoolMonitor", daemon=True)
        self.mon.start()

    def work(self):
        while self.alive:
            try:
                c, a, bh, bp = self.q.get(timeout=0.5)
            except queue.Empty:
                continue
            nm = threading.current_thread().name
            tlog(f"Connection dequeued, assigned to {nm}")
            tlog(f"Connection from {a[0]}:{a[1]}")
            with self.lock: self.busy.add(nm)
            try:
                serve_client(c, a, bh, bp)
            finally:
                with self.lock: self.busy.discard(nm)
                self.q.task_done()

    def push(self, item):
        try:
            if self.count() >= self.n:
                log("Warning: Thread pool saturated, queuing connection")
            self.q.put_nowait(item)
            log("Connection queued")
            return True
        except queue.Full:
            return False

    def count(self):
        with self.lock: return len(self.busy)

    def watch(self):
        while self.alive:
            time.sleep(30)
            log(f"Thread pool status: {self.count()}/{self.n} active")

    def stop(self):
        self.alive = False
        for t in self.workers:
            t.join(timeout=1.0)

#  main / accept loop
def main():
    ap = argparse.ArgumentParser()
    ap.add_argument("port", nargs="?", type=int, default=port)
    ap.add_argument("host", nargs="?", default=host)
    ap.add_argument("threads", nargs="?", type=int, default=threads)
    args = ap.parse_args()

    bind_host = args.host
    bind_port = args.port
    max_threads = args.threads if args.threads > 0 else threads

    os.makedirs(resources_dir, exist_ok=True)
    log(f"HTTP Server started on http://{bind_host}:{bind_port}")
    log(f"Thread pool size: {max_threads}")
    log(f"Serving files from 'resources' directory")
    log(f"Press Ctrl+C to stop the server")

    pool = ThreadPool(max_threads)
    with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
        s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
        s.bind((bind_host, bind_port)); s.listen(backlog)
        while True:
            try:
                c, ainfo = s.accept()
                if not pool.push((c, ainfo, bind_host, bind_port)):
                    log("Warning: Thread pool saturated, returning 503")
                    hdrs = {"Content-Type":"text/html; charset=utf-8","Connection":"close","Retry-After":"1"}
                    bod = (b"<!doctype html><html><body><h1>503 Service Unavailable</h1>"
                           b"<p>Server is busy. Please try again.</p></body></html>")
                    try: send_resp(c, 503, hdrs, bod)
                    except: pass
                    try: c.close()
                    except: pass
            except KeyboardInterrupt:
                break
            except:
                continue
    pool.stop()

if __name__ == "__main__":
    main()