130 lines
7.0 KiB
PHP
130 lines
7.0 KiB
PHP
<?php
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/**
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* login_confirm.php — Step 2 of 2-factor login: OTP verification + session creation
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*
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* Called by: login page AJAX after the user submits the OTP from their email.
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* Input: $data['otp'] (the 6-digit code the user typed in)
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* All other data is sourced from $_SESSION (set by login_otp.php).
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*
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* This is the second and final step of the login flow. It re-derives the
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* expected OTP from the user's stored password hash, compares it against the
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* submitted value, checks the 5-minute expiry window, and — on success —
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* creates the authenticated login session.
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*
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* Full flow:
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* 1. Load credentials and user_id from session (written by login_otp.php).
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* 2. Fetch the user's full row by user_id to get the current password hash.
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* 3. Re-derive the expected OTP using the same HMAC-SHA1 algorithm as
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* login_otp.php (same secret key = password hash, same time_step = 180s).
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* Uses $_SESSION['otpTime'] as the reference timestamp so the counter
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* matches the one used when the OTP was generated.
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* 4. Check both conditions that must be true for the OTP to be valid:
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* a. The submitted OTP matches the re-derived expected value.
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* b. The elapsed time since otpTime is ≤ 5 minutes.
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* Fail either → return "Wrong OTP! Please try again."
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* 5. On success:
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* a. session_regenerate_id(true) — prevents session fixation attack by
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* issuing a new session ID and deleting the old one.
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* b. Generate a fresh CSRF token and store in session.
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* c. Write the authenticated login session keys:
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* login_status=1, login_username, login_name, login_surname,
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* login_company_id (from user's default_company).
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* 6. Return { success: 1, message: "Login Complete!" }.
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*
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* Why OTP is re-derived rather than compared against $_SESSION['otp']:
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* Re-deriving from the password hash ensures the OTP is still valid even if
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* the session was tampered with — an attacker who can write to $_SESSION
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* cannot forge a valid OTP without also knowing the password hash.
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*
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* Session keys read:
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* login_data['username'], login_data['password'], login_user_id, otpTime
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*
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* Session keys written:
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* login_status, login_username, login_name, login_surname, login_company_id,
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* csrf_token
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*
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* Response JSON:
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* On success: { "success": 1, "message": "Login Complete!" }
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* On failure: { "message": "Wrong OTP! Please try again. (Our OTP is valid for 5 minute)" }
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*/
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require '../../../session.php';
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require '../../../config.php';
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require '../../../preset.php';
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require '../../../assets/utils/db_auth.php';
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// ── Step 1: Load session state written by login_otp.php ───────────────────────
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$data["username"] = $_SESSION["login_data"]['username'];
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$data["password"] = $_SESSION["login_data"]['password'];
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$user_id = $_SESSION["login_user_id"];
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// ── Step 2: Fetch user record — need password hash to re-derive the OTP ───────
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$sth = $pdo1->prepare("select * from user where user_id = :user_id limit 1;");
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$sth->execute([":user_id" => $user_id]);
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$temp = $sth->fetch(PDO::FETCH_ASSOC);
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// ── Step 3: Re-derive expected OTP ────────────────────────────────────────────
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// Uses $_SESSION['otpTime'] (set when the OTP was generated) as the TOTP
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// counter base. This is the same algorithm used in login_otp.php and
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// request_new_otp.php — any change to one must be reflected in all three.
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function generateOTP($sercet_key, $time_step = 180, $length = 6) {
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$counter = floor($_SESSION["otpTime"] / $time_step);
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$data = pack("NN", 0, $counter);
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$hash = hash_hmac('sha1', $data, $sercet_key, true);
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$offset = ord(substr($hash, -1)) & 0x0F;
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$value = unpack("N", substr($hash, $offset, 4));
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$otp = ($value[1] & 0x7FFFFFFF) % pow(10, $length);
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return str_pad(strval($otp), $length, '0', STR_PAD_LEFT);
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}
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$otp = generateOTP($temp["password"]);
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// ── Step 3b: Calculate elapsed time since OTP was issued ──────────────────────
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// otpTime is the Unix timestamp stored by login_otp.php when the OTP was sent.
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// The diff is computed in minutes for the 5-minute validity window check.
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$otp_time = isset($_SESSION['otpTime']) ? (int)$_SESSION['otpTime'] : 0;
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$now = time();
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$otp_diff_seconds = max(0, $now - $otp_time);
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$otp_diff_minutes = $otp_diff_seconds / 60.0;
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// Store for debug convenience — visible in $_SESSION on the session inspect page
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$_SESSION["now"] = $now;
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$_SESSION["diff"] = $otp_diff_minutes;
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// ── Step 4: Validate OTP value and expiry ─────────────────────────────────────
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// Fails if either the code doesn't match OR more than 5 minutes have elapsed
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// since the OTP was issued. The two conditions are intentionally combined in one
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// error message to avoid leaking whether the code was correct but expired.
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if ($data["otp"] != $otp || $otp_diff_minutes > 5) {
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$answer["message"] = "Wrong OTP! Please try again. (Our OTP is valid for 5 minute)";
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exit(json_encode($answer));
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}
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// ── Step 5a: Regenerate session ID ────────────────────────────────────────────
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// session_regenerate_id(true) issues a brand-new session ID and deletes the old
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// session file, preventing session fixation attacks where an attacker pre-sets
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// a session ID before the user logs in.
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session_regenerate_id(true);
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// ── Step 5b: Issue CSRF token ─────────────────────────────────────────────────
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// A fresh 256-bit token is generated here and stored in session. All subsequent
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// POST requests from the authenticated app must include this token in the
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// X-CSRF-Token header (validated by individual engine endpoints).
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$_SESSION['csrf_token'] = bin2hex(random_bytes(32));
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// ── Step 5c: Write authenticated login session ────────────────────────────────
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// These keys are read by db_auth.php on every subsequent request to gate access.
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// login_company_id is the user's default_company — used to scope all DB queries.
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$_SESSION["login_status"] = 1;
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$_SESSION["login_user_id"] = (int)$temp["user_id"];
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$_SESSION["login_username"] = $temp["username"];
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$_SESSION["login_name"] = $temp["name"];
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$_SESSION["login_surname"] = $temp["surname"];
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$_SESSION["login_company_id"] = $temp["default_company"];
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$_SESSION["login_profile_picture"] = $temp["profile_picture"] ?? '';
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// ── Step 6: Respond ───────────────────────────────────────────────────────────
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$answer["success"] = 1;
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$answer["message"] = "Login Complete!";
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exit(json_encode($answer)); |