// handleOptionalParameters parses the optional parameters as described in BEP
// 41 and updates an announce with the values parsed.
func handleOptionalParameters(packet []byte) (bittorrent.Params, error) {
if len(packet) == 0 {
return bittorrent.ParseURLData("")
}
var buf = newBuffer()
defer buf.free()
for i := 0; i < len(packet); {
option := packet[i]
switch option {
case optionEndOfOptions:
return bittorrent.ParseURLData(buf.String())
case optionNOP:
i++
case optionURLData:
if i+1 >= len(packet) {
return nil, errMalformedPacket
}
length := int(packet[i+1])
if i+2+length > len(packet) {
return nil, errMalformedPacket
}
n, err := buf.Write(packet[i+2 : i+2+length])
if err != nil {
return nil, err
}
if n != length {
return nil, fmt.Errorf("expected to write %d bytes, wrote %d", length, n)
}
i += 2 + length
default:
return nil, errUnknownOptionType
}
}
return bittorrent.ParseURLData(buf.String())
}
// ParseScrape parses an bittorrent.ScrapeRequest from an http.Request.
func ParseScrape(r *http.Request) (*bittorrent.ScrapeRequest, error) {
qp, err := bittorrent.ParseURLData(r.RequestURI)
if err != nil {
return nil, err
}
infoHashes := qp.InfoHashes()
if len(infoHashes) < 1 {
return nil, bittorrent.ClientError("no info_hash parameter supplied")
}
request := &bittorrent.ScrapeRequest{
InfoHashes: infoHashes,
Params: qp,
}
return request, nil
}
// ParseAnnounce parses an bittorrent.AnnounceRequest from an http.Request.
//
// If allowIPSpoofing is true, IPs provided via params will be used.
// If realIPHeader is not empty string, the first value of the HTTP Header with
// that name will be used.
func ParseAnnounce(r *http.Request, realIPHeader string, allowIPSpoofing bool) (*bittorrent.AnnounceRequest, error) {
qp, err := bittorrent.ParseURLData(r.RequestURI)
if err != nil {
return nil, err
}
request := &bittorrent.AnnounceRequest{Params: qp}
eventStr, _ := qp.String("event")
request.Event, err = bittorrent.NewEvent(eventStr)
if err != nil {
return nil, bittorrent.ClientError("failed to provide valid client event")
}
compactStr, _ := qp.String("compact")
request.Compact = compactStr != "" && compactStr != "0"
infoHashes := qp.InfoHashes()
if len(infoHashes) < 1 {
return nil, bittorrent.ClientError("no info_hash parameter supplied")
}
if len(infoHashes) > 1 {
return nil, bittorrent.ClientError("multiple info_hash parameters supplied")
}
request.InfoHash = infoHashes[0]
peerID, ok := qp.String("peer_id")
if !ok {
return nil, bittorrent.ClientError("failed to parse parameter: peer_id")
}
if len(peerID) != 20 {
return nil, bittorrent.ClientError("failed to provide valid peer_id")
}
request.Peer.ID = bittorrent.PeerIDFromString(peerID)
request.Left, err = qp.Uint64("left")
if err != nil {
return nil, bittorrent.ClientError("failed to parse parameter: left")
}
request.Downloaded, err = qp.Uint64("downloaded")
if err != nil {
return nil, bittorrent.ClientError("failed to parse parameter: downloaded")
}
request.Uploaded, err = qp.Uint64("uploaded")
if err != nil {
return nil, bittorrent.ClientError("failed to parse parameter: uploaded")
}
numwant, err := qp.Uint64("numwant")
if err != nil {
return nil, bittorrent.ClientError("failed to parse parameter: numwant")
}
request.NumWant = uint32(numwant)
port, err := qp.Uint64("port")
if err != nil {
return nil, bittorrent.ClientError("failed to parse parameter: port")
}
request.Peer.Port = uint16(port)
request.Peer.IP = requestedIP(r, qp, realIPHeader, allowIPSpoofing)
if request.Peer.IP == nil {
return nil, bittorrent.ClientError("failed to parse peer IP address")
}
// Sanitize IPv4 addresses to 4 bytes.
if ip := request.Peer.IP.To4(); ip != nil {
request.Peer.IP = ip
}
return request, nil
}