Add local settings management

Add cellular-first ntfy delivery with WiFi fallback and safe SIM868 HTTP header framing.

Co-authored-by: Copilot <[email protected]>

modules/app_cellular.py

@@ -28,15 +28,11 @@ AT interface has a small internal buffer unsuited to multi-MB bodies.
 import os
 import time
 
-from modules import app_gps
-
-APN = os.getenv("YARIS_CELLULAR_APN", "")
-APN_USER = os.getenv("YARIS_CELLULAR_APN_USER", "")
-APN_PASS = os.getenv("YARIS_CELLULAR_APN_PASS", "")
-ENABLED = os.getenv("YARIS_CELLULAR_ENABLED", "") == "1"
+from modules import app_gps, app_sql
 
 GPRS_BRINGUP_TIMEOUT = 30   # seconds to wait for AT+CIICR / AT+CIFSR
 HTTP_ACTION_TIMEOUT = 60    # seconds to wait for the +HTTPACTION URC (2G/3G can be slow)
+HTTP_USERDATA_MAX_BYTES = 1024
 
 _gprs_context_up = False
 
@@ -48,9 +44,19 @@ class CellularError(Exception):
 
 def is_configured():
     """True once the user has filled in an APN and flipped the enabled flag
-    in db/upload_creds.env. Off by default - nothing cellular-related runs
-    unless explicitly opted into."""
-    return ENABLED and bool(APN)
+    in the Settings page or legacy environment configuration. Off by default -
+    nothing cellular-related runs unless explicitly opted into."""
+    enabled = app_sql.get_setting(
+        "cellular_enabled",
+        "1" if os.getenv("YARIS_CELLULAR_ENABLED", "") == "1" else "0",
+    )
+    return enabled == "1" and bool(get_apn())
+
+
+def get_apn():
+    return app_sql.get_setting(
+        "cellular_apn", os.getenv("YARIS_CELLULAR_APN", "")
+    )
 
 
 def _read_until(ser, terminators, timeout):
@@ -104,7 +110,16 @@ def _ensure_gprs_context():
 
         _at(ser, "AT+CGATT=1", timeout=10)
 
-        apn_cmd = f'AT+CSTT="{APN}","{APN_USER}","{APN_PASS}"'
+        apn = _validate_http_parameter(get_apn(), "APN")
+        apn_user = _validate_http_parameter(
+            os.getenv("YARIS_CELLULAR_APN_USER", ""),
+            "APN username",
+        )
+        apn_password = _validate_http_parameter(
+            os.getenv("YARIS_CELLULAR_APN_PASS", ""),
+            "APN password",
+        )
+        apn_cmd = f'AT+CSTT="{apn}","{apn_user}","{apn_password}"'
         _at(ser, apn_cmd, timeout=10)
 
         _at(ser, "AT+CIICR", timeout=GPRS_BRINGUP_TIMEOUT)
@@ -116,8 +131,22 @@ def _ensure_gprs_context():
         _gprs_context_up = True
 
 
-def http_post_json(url, body_bytes, extra_headers, timeout=HTTP_ACTION_TIMEOUT):
-    """POST a small JSON body to `url` via the modem's built-in HTTP client.
+def _validate_http_parameter(value, label):
+    if not isinstance(value, str) or any(
+        char in value for char in ('"', "\r", "\n")
+    ):
+        raise CellularError(f"{label} contains unsupported characters")
+    return value
+
+
+def http_post(
+    url,
+    body_bytes,
+    extra_headers,
+    content_type="application/json",
+    timeout=HTTP_ACTION_TIMEOUT,
+):
+    """POST a small body to `url` via the modem's built-in HTTP client.
 
     Returns (status_code, response_body_bytes). Raises CellularError on any
     failure (modem not responding, no network attach, HTTP-layer failure,
@@ -126,6 +155,18 @@ def http_post_json(url, body_bytes, extra_headers, timeout=HTTP_ACTION_TIMEOUT):
     """
     if not is_configured():
         raise CellularError("cellular fallback not configured (APN/enabled flag not set)")
+    _validate_http_parameter(url, "URL")
+    _validate_http_parameter(content_type, "Content type")
+    for name, value in extra_headers.items():
+        _validate_http_parameter(name, "Header name")
+        _validate_http_parameter(value, f"{name} header")
+    header_lines = r"\r\n".join(
+        f"{name}: {value}" for name, value in extra_headers.items()
+    )
+    if header_lines:
+        header_lines += r"\r\n"
+    if len(header_lines.encode("utf-8")) > HTTP_USERDATA_MAX_BYTES:
+        raise CellularError("HTTP headers exceed the modem's 1024-byte limit")
 
     _ensure_gprs_context()
 
@@ -153,10 +194,14 @@ def http_post_json(url, body_bytes, extra_headers, timeout=HTTP_ACTION_TIMEOUT):
                         "cellular is unavailable on this firmware. Consider a "
                         "plain-HTTP router port-forward path for cellular use."
                     )
-            _at(ser, 'AT+HTTPPARA="CONTENT","application/json"', timeout=5)
+            _at(ser, f'AT+HTTPPARA="CONTENT","{content_type}"', timeout=5)
 
-            header_lines = "".join(f"{k}: {v}\r\n" for k, v in extra_headers.items())
-            _at(ser, f'AT+HTTPPARA="USERDATA","{header_lines}"', timeout=5)
+            if header_lines:
+                _at(
+                    ser,
+                    f'AT+HTTPPARA="USERDATA","{header_lines}"',
+                    timeout=5,
+                )
 
             _at(
                 ser,
@@ -192,3 +237,13 @@ def http_post_json(url, body_bytes, extra_headers, timeout=HTTP_ACTION_TIMEOUT):
                 _at(ser, "AT+HTTPTERM", timeout=5)
             except CellularError:
                 pass
+
+
+def http_post_json(url, body_bytes, extra_headers, timeout=HTTP_ACTION_TIMEOUT):
+    return http_post(
+        url,
+        body_bytes,
+        extra_headers,
+        content_type="application/json",
+        timeout=timeout,
+    )