adds torrent parser to support native torrent files when downloading

codex/bittorrent/torrentparser.nim

@@ -0,0 +1,41 @@
+import std/strutils
+import std/re
+
+import pkg/questionable/results
+import pkg/stew/byteutils
+import pkg/stew/base10
+
+import ../errors
+
+proc extractInfoFromTorrent*(torrentBytes: seq[byte]): ?!seq[byte] =
+  ## Extract the info from a torrent file
+  ##
+  ## params:
+  ##   torrentBytes: the torrent file bytes
+  ##
+  ## returns: the bytes containing only the content of the info dictionary
+  ##          or a failure if info is not found or invalid
+  let torrentStr = string.fromBytes(torrentBytes)
+  if torrentStr.contains("file tree") or torrentStr.contains("piece layers"):
+    return failure("Torrent v2 provided. Only v1 is currently supported.")
+  let infoKeyPos = torrentStr.find("info")
+  if infoKeyPos == -1:
+    return failure("Torrent file does not contain info dictionary.")
+  let infoStartPos = infoKeyPos + "info".len
+  if torrentStr[infoStartPos] != 'd':
+    return failure("Torrent file does not contain valid info dictionary.")
+
+  var matches = newSeq[tuple[first, last: int]](1)
+  let (_, piecesEndIndex) = torrentStr.findBounds(re"pieces(\d+):", matches)
+  if matches.len == 1:
+    let (first, last) = matches[0]
+    let piecesLenStr = torrentStr[first .. last]
+    without piecesLen =? Base10.decode(uint, piecesLenStr).mapFailure, err:
+      return failure("Error decoding pieces length: " & err.msg)
+    let piecesEndMarkerPos = piecesEndIndex + 1 + piecesLen.int
+    if torrentStr[piecesEndMarkerPos] != 'e':
+      return failure("Torrent file does not contain valid pieces.")
+    let infoDirStr = torrentStr[infoStartPos .. piecesEndMarkerPos]
+    infoDirStr.toBytes().success
+  else:
+    return failure("Torrent file does not contain valid pieces.")

codex/rest/api.nim

@@ -43,6 +43,7 @@ import ../utils/options
 import ../bittorrent/manifest
 import ../bittorrent/torrentdownloader
 import ../bittorrent/magnetlink
+import ../bittorrent/torrentparser
 
 import ../tarballs/[directorymanifest, directorydownloader, tarballnodeextensions]
 
@@ -681,6 +682,57 @@ proc initDataApi(node: CodexNodeRef, repoStore: RepoStore, router: var RestRoute
         Http422, "The magnet link does not contain a valid info hash."
       )
     await node.retrieveInfoHash(infoHash, resp = resp)
+    # return
+    #   RestApiResponse.response($magnetLink, Http200, "text/plain")
+
+  router.api(MethodOptions, "/api/codex/v1/torrent/torrent-file") do(
+    resp: HttpResponseRef
+  ) -> RestApiResponse:
+    if corsOrigin =? allowedOrigin:
+      resp.setCorsHeaders("POST", corsOrigin)
+      resp.setHeader(
+        "Access-Control-Allow-Headers", "content-type, content-disposition"
+      )
+
+    resp.status = Http204
+    await resp.sendBody("")
+
+  router.api(MethodPost, "/api/codex/v1/torrent/torrent-file") do(
+    contentBody: Option[ContentBody], resp: HttpResponseRef
+  ) -> RestApiResponse:
+    let mimeType = request.headers.getString(ContentTypeHeader)
+    echo "mimeType: ", mimeType
+    if mimeType != "application/json" and mimeType != "application/octet-stream":
+      return RestApiResponse.error(
+        Http422,
+        "Missing \"Content-Type\" header: expected either \"application/json\" or \"application/octet-stream\".",
+      )
+    without torrentBytes =? contentBody .? data:
+      return RestApiResponse.error(Http422, "No torrent file content provided.")
+    var infoBytes: seq[byte]
+    if mimeType == "application/json":
+      without torrentManifest =? BitTorrentManifest.fromJson(torrentBytes):
+        return RestApiResponse.error(Http422, "Invalid torrent JSON file content.")
+      echo "torrentManifest: ", torrentManifest
+      let torrentInfo = torrentManifest.info
+      # very basic validation for now
+      if torrentInfo.length == 0 or torrentInfo.pieceLength == 0 or
+          torrentInfo.pieces.len == 0:
+        return
+          RestApiResponse.error(Http422, "The torrent file is invalid or incomplete.")
+      # return RestApiResponse.response($torrentInfo, contentType = "text/plain")
+      infoBytes = bencode(torrentInfo)
+    else:
+      without infoBencoded =? extractInfoFromTorrent(torrentBytes), err:
+        return RestApiResponse.error(
+          Http422, "Failed extracting info directory from the torrent file."
+        )
+      infoBytes = infoBencoded
+    without infoHash =? MultiHash.digest($Sha1HashCodec, infoBytes).mapFailure, err:
+      return RestApiResponse.error(
+        Http422, "The torrent file does not contain a valid info hash."
+      )
+    return await node.retrieveInfoHash(infoHash, resp = resp)
 
   router.api(MethodGet, "/api/codex/v1/torrent/{infoHash}/network/stream") do(
     infoHash: MultiHash, resp: HttpResponseRef

tests/codex/bittorrent/testtorrentparser.nim

@@ -0,0 +1,48 @@
+import std/sequtils
+
+import pkg/unittest2
+
+import pkg/libp2p/[multicodec, multihash]
+import pkg/questionable/results
+import pkg/stew/byteutils
+
+import ../examples
+
+import pkg/codex/bittorrent/manifest/manifest
+import pkg/codex/bittorrent/torrentParser
+
+suite "torrentParser":
+  test "extracts info directory bytes from the torrent binary data":
+    let pieces = @[
+      "21FEBA308CD51E9ACF88417193A9EA60F0F84646",
+      "3D4A8279853DA2DA355A574740217D446506E8EB",
+      "1AD686B48B9560B15B8843FD00E7EC1B59624B09",
+      "5015E7DA0C40350624C6B5A1FED1DB39720B726C",
+    ].map(
+      proc(hash: string): MultiHash =
+        let bytes = hash.hexToSeqByte.catch.tryGet()
+        MultiHash.init($Sha1HashCodec, bytes).mapFailure.tryGet()
+    )
+
+    let info = BitTorrentInfo(
+      length: 1048576, pieceLength: 262144, pieces: pieces, name: some("data1M.bin")
+    )
+    let encodedInfo = info.bencode()
+    let infoHash = MultiHash.digest($Sha1HashCodec, encodedInfo).mapFailure.tryGet()
+    let torrentBytes = ("d4:info" & string.fromBytes(encodedInfo) & "e").toBytes()
+    # let torrentBytesHex = byteutils.toHex(torrentBytes)
+
+    # check torrentBytesHex == "64343a696e666f64363a6c656e677468693130343835373665343a6e616d6531303a64617461314d2e62696e31323a7069656365206c656e6774686932363231343465363a70696563657338303a21feba308cd51e9acf88417193a9ea60f0f846463d4a8279853da2da355a574740217d446506e8eb1ad686b48b9560b15b8843fd00e7ec1b59624b095015e7da0c40350624c6b5a1fed1db39720b726c6565"
+
+    let infoBytes = extractInfoFromTorrent(torrentBytes).tryGet()
+
+    # echo string.fromBytes(infoBytes)
+
+    # let infoBytesHex = byteutils.toHex(infoBytes)
+
+    # check infoBytesHex == "64363a6c656e677468693130343835373665343a6e616d6531303a64617461314d2e62696e31323a7069656365206c656e6774686932363231343465363a70696563657338303a21feba308cd51e9acf88417193a9ea60f0f846463d4a8279853da2da355a574740217d446506e8eb1ad686b48b9560b15b8843fd00e7ec1b59624b095015e7da0c40350624c6b5a1fed1db39720b726c65"
+
+    let extractedInfoHash =
+      MultiHash.digest($Sha1HashCodec, infoBytes).mapFailure.tryGet()
+
+    check extractedInfoHash == infoHash