add configurable size limit, allow arbitrary data if content-type is passed

index.js

@@ -9,6 +9,7 @@ const bodyParser = require('body-parser')
 const PORT = Number(process.env.PRINTSERVANT_PORT) || 3199
 const CONFIG = JSON.parse(process.env.PRINTSERVANT_CONFIG || 'null')
 const SECRET = process.env.PRINTSERVANT_SECRET || ''
+const MAX_SIZE_MB = Number(process.env.PRINTSERVANT_MAX_SIZE_MB) || 10
 
 if (!(PORT && CONFIG)) {
   throw new Error("PRINTSERVANT_PORT and PRINTSERVANT_CONFIG environment variables must be set")
@@ -59,10 +60,11 @@ app.get('/', (req, res) => {
       - Prints IPP attributes
     - GET /printers/:name/jobs
       - Prints IPP jobs
-    - POST /print?printer=:name (body: application/pdf or image/png)
+    - POST /print?printer=:name
       - Prints a PDF
       - ?printer= printer name or alias (case insensitive)
       - ?copies= (optional) number of copies (1-10 allowed)
+      - Body: PDF or PNG data; *or* any data if Content-Type header is passed
       - Response: 200 OK if sent to printer successfully (not necessarily printed), 4xx/5xx otherwise
   </pre>`)
 })
@@ -107,9 +109,9 @@ app.get('/printers/:name/jobs', (req, res) => {
 
 // --- Print API ---
 
-app.post('/print', bodyParser.raw({ type: '*/*', limit: 10_000_000 }), (req, res) => {
+app.post('/print', bodyParser.raw({ type: '*/*', limit: MAX_SIZE_MB * 1_000_000 }), (req, res) => {
-  const { body, query } = req
+  const { body, query, headers } = req
-  console.log("Received print job: ", { body, query })
+  console.log("Received print job: ", { body, query, headers })
 
   // validate query params
   const { printer: printerName, copies: copiesParam, ...otherParams } = query
@@ -130,15 +132,21 @@ app.post('/print', bodyParser.raw({ type: '*/*', limit: 10_000_000 }), (req, res
 
   // validate body
   if (!body || !body.length) {
-    res.status(400).send("No data received, please send a PDF")
+    res.status(400).send("No data received")
     return
   }
 
+  const contentType = headers['content-type']
+  const hasValidContentType = contentType
+    && contentType !== 'application/octet-stream'
+    && contentType !== 'application/x-www-form-urlencoded'
+
   const isPDF = body.subarray(0, 4).toString() === "%PDF"
   const isPNG = body.subarray(0, 8).equals(Buffer.from([0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a]))
 
-  if (!isPDF && !isPNG) {
+  const hasValidFormat = isPDF || isPNG || hasValidContentType
-    res.status(415).send("Unsupported media type, only PDF and PNG are supported")
+  if (!hasValidFormat) {
+    res.status(415).send("Unknown media type. Pass a PDF or PNG file, or set Content-Type header to print something else.")
     return
   }
 
@@ -152,7 +160,12 @@ app.post('/print', bodyParser.raw({ type: '*/*', limit: 10_000_000 }), (req, res
   // send print job
   const msg = {
     "operation-attributes-tag": {
-      "document-format": isPNG ? "image/png" : "application/pdf",
+      "document-format": (() => {
+        if (isPDF) return "application/pdf"
+        if (isPNG) return "image/png"
+        if (contentType) return contentType
+        throw new Error('unreachable')
+      })(),
     },
     "job-attributes-tag": {
       "copies": copies,