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Example script for PDF Highlighter that gets document path from database and obfuscates document access URL

Getting document path from database and obfuscating access URL

Requirements for this exercise are:

  • Access PDF documents using GUID identifiers.
  • GUIDs are stored in MuSQL database and point to PDF files on accessible via server file system.
  • Users should not be able to get direct URL to PDF file.

The approach used to address the requirements:

  • We extend PDF Highlighter functionality with a custom script.
  • Document highlighting URLs composed by search application will send GUID as "uri" parameter.
  • When handling the highlighting request, PDF Highlighter server invokes our script function "uriToFile" that queries the database, stores file path to short term cache and returns the file to Highlighter.
  • We override result document serving path so that HTML5 PDF viewer gets file from PDF Highlighter's "/cached-document" endpoint, passing request "uri" (which is our GUID).
  • When handling the "/cached-document" request, PDF Highlighter invokes our "cachedFile" function.
  • cachedFile will lookup for file path in cache and return if available. Access to file after the expiration time results with 404 error.
highlighter {
service {
scripting {
files = ["D:/project-data/my-script.groovy"]
uriFilterFn = "uriToFile" # hook to our function that transforms uri paramete to PDF file path
cachedDocumentProviderFn = "cachedFile" # hook to function responsible for locating
}
}
# override default document serving paths so that document is requested from "/cached-document/" endpoint
serveViewerHighlightedPdf = "{serviceUrl}/viewer/?file=/cached-document/{request.uri:urlencoded}&highlightsFile={serviceUrl:urlencoded}{/hits/:urlencoded}{hitsRef:urlencoded}&nativePrint={viewerUseBrowserPdfPrint}#page={firstHitPage}"
serveOriginalPdfInViewer = "{serviceUrl}/viewer/?file=/cached-document/{request.uri:urlencoded}&nativePrint={viewerUseBrowserPdfPrint}"
# override default rules so we use HTML5 PDF viewer for all user agents
documentServingPathRules = []
documentServingPath = serveViewerHighlightedPdf
# ... other settings ...
}
import groovy.sql.Sql
import groovy.transform.Field
import java.util.concurrent.TimeUnit
import com.google.common.cache.Cache
import com.google.common.cache.CacheBuilder
/*
PDF Highlighter initializes global scope with:
scriptPath - path used to load the script
log - an instance of org.slf4j.Logger
*/
// global variables
@Field Sql sql
@Field Cache idToFileCache
def init() {
log.info("Init script {}", scriptPath)
// init cache for file paths
idToFileCache = CacheBuilder.newBuilder()
.maximumSize(1000)
.expireAfterWrite(60, TimeUnit.SECONDS)
.expireAfterAccess(30, TimeUnit.SECONDS)
.build()
// open database connection (keeping it open while the script is loaded)
dbConnect()
}
def destroy() {
log.info("Unloading script {}", scriptPath)
try {
if (sql != null)
sql.close()
} catch (Exception e) {
log.info(e.message)
}
}
def dbConnect() {
def url = 'jdbc:mysql://localhost:3306/your_database'
def user = 'root'
def password = ''
def driver = 'com.mysql.jdbc.Driver'
sql = Sql.newInstance(url, user, password, driver)
log.info('Connected to {}', url)
}
def uriToFile(uri) {
log.debug("requested pdf for {}", uri)
def docId = uri, docRow
// TODO: query your database
//docRow = sql.firstRow('SELECT file_path FROM documents WHERE id = ?', [docId])
if (docRow) {
String path = docRow.file_path
log.info("PDF path from db: {}", path)
idToFileCache.put(docId, path)
// At this point we could return document 'path' (string) and PDF Highlighter would pass it
// through regex mapping rules (if setup).
// However, if we return a File instance, Highlighter will use it without further filtering.
return new File(path)
}
else {
log.warn('Not found file for {} (uri:{})', docId, uri)
}
}
def cachedFile(id) {
String path = idToFileCache.getIfPresent(id)
log.info('File path for {}: {}', id, path)
if (path != null) {
return new File(path)
}
}
@jobjects

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@jobjects jobjects commented Jul 21, 2018

Note that PDF Highlighter doesn't come with JDBC drivers. To make database driver available to PDF Highlighter, copy jdbc jar file (e.g. mysql-connector-java-5.1.41-bin.jar) to "lib" folder below your script location (e.g. "D:/project-data/lib" for the above example).

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