1 files changed, 56 insertions, 0 deletions

diff --git a/client/src/assets/player/p2p-media-loader/segment-validator.ts b/client/src/assets/player/p2p-media-loader/segment-validator.ts
new file mode 100644
index 000000000..8f4922daa
--- /dev/null
+++ b/client/src/assets/player/p2p-media-loader/segment-validator.ts
@@ -0,0 +1,56 @@
+import { Segment } from 'p2p-media-loader-core'
+import { basename } from 'path'
+
+function segmentValidatorFactory (segmentsSha256Url: string) {
+  const segmentsJSON = fetchSha256Segments(segmentsSha256Url)
+
+  return async function segmentValidator (segment: Segment) {
+    const segmentName = basename(segment.url)
+
+    const hashShouldBe = (await segmentsJSON)[segmentName]
+    if (hashShouldBe === undefined) {
+      throw new Error(`Unknown segment name ${segmentName} in segment validator`)
+    }
+
+    const calculatedSha = bufferToEx(await sha256(segment.data))
+    if (calculatedSha !== hashShouldBe) {
+      throw new Error(`Hashes does not correspond for segment ${segmentName} (expected: ${hashShouldBe} instead of ${calculatedSha})`)
+    }
+  }
+}
+
+// ---------------------------------------------------------------------------
+
+export {
+  segmentValidatorFactory
+}
+
+// ---------------------------------------------------------------------------
+
+function fetchSha256Segments (url: string) {
+  return fetch(url)
+    .then(res => res.json())
+    .catch(err => {
+      console.error('Cannot get sha256 segments', err)
+      return {}
+    })
+}
+
+function sha256 (data?: ArrayBuffer) {
+  if (!data) return undefined
+
+  return window.crypto.subtle.digest('SHA-256', data)
+}
+
+// Thanks: https://stackoverflow.com/a/53307879
+function bufferToEx (buffer?: ArrayBuffer) {
+  if (!buffer) return ''
+
+  let s = ''
+  const h = '0123456789abcdef'
+  const o = new Uint8Array(buffer)
+
+  o.forEach((v: any) => s += h[ v >> 4 ] + h[ v & 15 ])
+
+  return s
+}