// ParseAnnounce parses an AnnounceRequest from a UDP request.
//
// If allowIPSpoofing is true, IPs provided via params will be used.
//
// If v6 is true the announce will be parsed as an IPv6 announce "the
// opentracker way", see
// http://opentracker.blog.h3q.com/2007/12/28/the-ipv6-situation/
func ParseAnnounce(r Request, allowIPSpoofing, v6 bool) (*bittorrent.AnnounceRequest, error) {
ipEnd := 84 + net.IPv4len
if v6 {
ipEnd = 84 + net.IPv6len
}
if len(r.Packet) < ipEnd+10 {
return nil, errMalformedPacket
}
infohash := r.Packet[16:36]
peerID := r.Packet[36:56]
downloaded := binary.BigEndian.Uint64(r.Packet[56:64])
left := binary.BigEndian.Uint64(r.Packet[64:72])
uploaded := binary.BigEndian.Uint64(r.Packet[72:80])
eventID := int(r.Packet[83])
if eventID >= len(eventIDs) {
return nil, errMalformedEvent
}
ip := r.IP
ipbytes := r.Packet[84:ipEnd]
if allowIPSpoofing {
// Make sure the bytes are copied to a new slice.
copy(ip, net.IP(ipbytes))
}
if !allowIPSpoofing && r.IP == nil {
// We have no IP address to fallback on.
return nil, errMalformedIP
}
numWant := binary.BigEndian.Uint32(r.Packet[ipEnd+4 : ipEnd+8])
port := binary.BigEndian.Uint16(r.Packet[ipEnd+8 : ipEnd+10])
params, err := handleOptionalParameters(r.Packet[ipEnd+10:])
if err != nil {
return nil, err
}
return &bittorrent.AnnounceRequest{
Event: eventIDs[eventID],
InfoHash: bittorrent.InfoHashFromBytes(infohash),
NumWant: uint32(numWant),
Left: left,
Downloaded: downloaded,
Uploaded: uploaded,
Peer: bittorrent.Peer{
ID: bittorrent.PeerIDFromBytes(peerID),
IP: ip,
Port: port,
},
Params: params,
}, nil
}
// ParseScrape parses a ScrapeRequest from a UDP request.
func ParseScrape(r Request) (*bittorrent.ScrapeRequest, error) {
// If a scrape isn't at least 36 bytes long, it's malformed.
if len(r.Packet) < 36 {
return nil, errMalformedPacket
}
// Skip past the initial headers and check that the bytes left equal the
// length of a valid list of infohashes.
r.Packet = r.Packet[16:]
if len(r.Packet)%20 != 0 {
return nil, errMalformedPacket
}
// Allocate a list of infohashes and append it to the list until we're out.
var infohashes []bittorrent.InfoHash
for len(r.Packet) >= 20 {
infohashes = append(infohashes, bittorrent.InfoHashFromBytes(r.Packet[:20]))
r.Packet = r.Packet[20:]
}
return &bittorrent.ScrapeRequest{
InfoHashes: infohashes,
}, nil
}
