fix(capture): make printer-byte parsing binary-safe

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@fieldlens/print",
-  "version": "0.1.4",
+  "version": "0.1.5",
   "private": true,
   "type": "module",
   "scripts": {

src-tauri/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "fieldlens-print"
-version = "0.1.4"
+version = "0.1.5"
 description = "FieldLens print-stream barcode capture companion"
 authors = ["Arrowstack"]
 edition = "2021"

src-tauri/src/capture.rs

@@ -391,7 +391,14 @@ fn process_payload(
     error: Option<String>,
 ) {
     let id = Uuid::new_v4().to_string();
-    let barcodes = extract_barcodes(&bytes);
+    let (barcodes, parse_error) = match std::panic::catch_unwind(|| extract_barcodes(&bytes)) {
+        Ok(found) => (found, None),
+        Err(_) => (
+            Vec::new(),
+            Some("barcode parser failed; print bytes were still captured and forwarded".to_string()),
+        ),
+    };
+    let error = error.or(parse_error);
 
     for barcode in &barcodes {
         state.queue_scan(

src-tauri/src/zpl.rs

@@ -1,12 +1,14 @@
 use crate::model::DecodedBarcode;
 
 pub fn extract_barcodes(bytes: &[u8]) -> Vec<DecodedBarcode> {
-    let text = String::from_utf8_lossy(bytes);
-    extract_from_zpl(&text)
+    extract_from_zpl_bytes(bytes)
 }
 
 pub fn extract_from_zpl(input: &str) -> Vec<DecodedBarcode> {
-    let bytes = input.as_bytes();
+    extract_from_zpl_bytes(input.as_bytes())
+}
+
+fn extract_from_zpl_bytes(bytes: &[u8]) -> Vec<DecodedBarcode> {
     let mut index = 0usize;
     let mut pending_format: Option<String> = None;
     let mut barcodes = Vec::new();
@@ -18,7 +20,7 @@ pub fn extract_from_zpl(input: &str) -> Vec<DecodedBarcode> {
         }
 
         let command_start = index;
-        let command = &input[index + 1..index + 3];
+        let command = &bytes[index + 1..index + 3];
         index += 3;
 
         if let Some(format) = barcode_format(command) {
@@ -26,14 +28,13 @@ pub fn extract_from_zpl(input: &str) -> Vec<DecodedBarcode> {
             continue;
         }
 
-        if command == "FD" {
-            let end = input[index..]
-                .find("^FS")
+        if command == b"FD" {
+            let end = find_bytes(&bytes[index..], b"^FS")
                 .map(|offset| index + offset)
-                .unwrap_or(input.len());
+                .unwrap_or(bytes.len());
             if let Some(format) = pending_format.take() {
-                let raw = input[index..end].trim();
-                let value = normalize_field_data(raw);
+                let raw = String::from_utf8_lossy(&bytes[index..end]);
+                let value = normalize_field_data(raw.trim());
                 if !value.is_empty() {
                     barcodes.push(DecodedBarcode { format, value });
                 }
@@ -42,7 +43,7 @@ pub fn extract_from_zpl(input: &str) -> Vec<DecodedBarcode> {
             continue;
         }
 
-        if command == "FS" || command == "XZ" {
+        if command == b"FS" || command == b"XZ" {
             pending_format = None;
         }
 
@@ -54,23 +55,30 @@ pub fn extract_from_zpl(input: &str) -> Vec<DecodedBarcode> {
     barcodes
 }
 
-fn barcode_format(command: &str) -> Option<&'static str> {
+fn barcode_format(command: &[u8]) -> Option<&'static str> {
     match command {
-        "BC" => Some("CODE_128"),
-        "B3" => Some("CODE_39"),
-        "BE" => Some("EAN_13"),
-        "B8" => Some("EAN_8"),
-        "BU" => Some("UPC_A"),
-        "B9" => Some("UPC_E"),
-        "B2" => Some("ITF"),
-        "BQ" => Some("QR_CODE"),
-        "BX" => Some("DATA_MATRIX"),
-        "B7" => Some("PDF_417"),
-        "BA" => Some("CODE_93"),
+        b"BC" => Some("CODE_128"),
+        b"B3" => Some("CODE_39"),
+        b"BE" => Some("EAN_13"),
+        b"B8" => Some("EAN_8"),
+        b"BU" => Some("UPC_A"),
+        b"B9" => Some("UPC_E"),
+        b"B2" => Some("ITF"),
+        b"BQ" => Some("QR_CODE"),
+        b"BX" => Some("DATA_MATRIX"),
+        b"B7" => Some("PDF_417"),
+        b"BA" => Some("CODE_93"),
         _ => None,
     }
 }
 
+fn find_bytes(haystack: &[u8], needle: &[u8]) -> Option<usize> {
+    if needle.is_empty() {
+        return Some(0);
+    }
+    haystack.windows(needle.len()).position(|window| window == needle)
+}
+
 fn normalize_field_data(raw: &str) -> String {
     let mut value = raw.to_string();
 
@@ -124,4 +132,15 @@ mod tests {
         let zpl = "^XA^FO10,10^A0N,30,30^FDNOT-A-BARCODE^FS^XZ";
         assert!(extract_from_zpl(zpl).is_empty());
     }
+
+    #[test]
+    fn arbitrary_binary_printer_data_never_panics() {
+        let payload = [
+            0x1b, b'@', 0xff, 0x00, 0xfe, b'^', 0xff, 0xfd, 0x1b, b'(', b'G',
+            0x10, 0x00, 0x80, 0x81, 0x82, b'^', b'F', b'D', 0xf0, 0x9f, 0x92,
+            0xa9, b'^', b'F', b'S',
+        ];
+        let found = extract_barcodes(&payload);
+        assert!(found.is_empty());
+    }
 }

src-tauri/tauri.conf.json

@@ -1,7 +1,7 @@
 {
   "$schema": "https://schema.tauri.app/config/2",
   "productName": "FieldLens Print",
-  "version": "0.1.4",
+  "version": "0.1.5",
   "identifier": "dev.arrowstack.fieldlens.print",
   "build": {
     "beforeDevCommand": "npm run dev",

src/main.ts

@@ -85,7 +85,7 @@ let config: AppConfig
 let jobs: Job[] = []
 let status: Status
 let loginTimer: number | undefined
-let currentVersion = '0.1.4'
+let currentVersion = '0.1.5'
 let bundleType: BundleType | null = null
 let availableUpdate: Update | null = null
 let availableManualUpdate: ManualUpdate | null = null