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Examples: safer Flask and FastAPI defaults #7

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Merged
boxlinknet merged 1 commit into from
Nov 8, 2026
Merged

Examples: safer Flask and FastAPI defaults #7

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22 changes: 14 additions & 8 deletions examples/08-flask.py
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Original file line number Diff line number Diff line change
Expand Up @@ -22,10 +22,16 @@

from __future__ import annotations

import os
import secrets
import time
from typing import Dict


def _one_line(value: object) -> str:
"""Log-safe text: CR and LF removed so a value cannot forge log lines (2026-11-08 example hardening)."""
return str(value).replace("\r", " ").replace("\n", " ")

# ── Flask application factory ────────────────────────────────────────────────

try:
Expand Down Expand Up @@ -83,7 +89,9 @@ def health():
ok, balance, error = get_sms().verify()
if ok:
return jsonify({"ok": True, "balance": balance})
return jsonify({"ok": False, "error": error}), 503
# 2026-11-08 13:38 +03: details stay in the server log, the client gets a generic message (CodeQL stack-trace-exposure)
app.logger.error("kwtSMS verify failed: %s", _one_line(error))
return jsonify({"ok": False, "error": "SMS gateway unavailable"}), 503

@app.post("/otp/send")
def otp_send():
Expand Down Expand Up @@ -111,7 +119,7 @@ def otp_send():

if result["result"] != "OK":
# Log the error server-side, but never expose raw API codes to clients
app.logger.error("kwtSMS send failed: %s", result)
app.logger.error("kwtSMS send failed: %s", _one_line(result)) # 2026-11-08 13:38 +03: no newlines in logs
return jsonify({"error": "Could not send verification code. Try again."}), 500

_otp_store[phone] = {
Expand Down Expand Up @@ -187,11 +195,9 @@ def sms_send():
"balance_after": result.get("balance-after"),
})

return jsonify({
"ok": False,
"code": result.get("code"),
"error": result.get("description"),
}), 500
# 2026-11-08 13:38 +03: API error details go to the server log only (CodeQL stack-trace-exposure)
app.logger.error("kwtSMS send failed: %s", _one_line(result))
return jsonify({"ok": False, "error": "Could not send the SMS. Try again."}), 500

return app

Expand All @@ -209,4 +215,4 @@ def sms_send():
print(" POST /otp/send (send OTP)")
print(" POST /otp/verify (verify OTP)")
print(" POST /sms/send (send arbitrary SMS)")
app.run(debug=True)
app.run(debug=os.environ.get("FLASK_DEBUG") == "1") # 2026-11-08 13:38 +03: never debug by default
2 changes: 1 addition & 1 deletion examples/09-fastapi.py
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Original file line number Diff line number Diff line change
Expand Up @@ -134,7 +134,7 @@ def otp_send(body: OTPSendRequest):
if result["result"] != "OK":
# Log full error server-side; never expose raw API codes to clients
import logging
logging.error("kwtSMS send failed: %s", result)
logging.error("kwtSMS send failed: %s", str(result).replace("\r", " ").replace("\n", " ")) # 2026-11-08 13:38 +03: no newlines in logs
raise HTTPException(status_code=500, detail="Could not send verification code. Try again.")

_otp_store[phone] = {
Expand Down
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