67 lines
1.4 KiB
Go
67 lines
1.4 KiB
Go
package core
|
|
|
|
func fragUDPMessage(m udpMessage, maxSize int) []udpMessage {
|
|
if m.Size() <= maxSize {
|
|
return []udpMessage{m}
|
|
}
|
|
fullPayload := m.Data
|
|
maxPayloadSize := maxSize - m.HeaderSize()
|
|
off := 0
|
|
fragID := uint8(0)
|
|
fragCount := uint8((len(fullPayload) + maxPayloadSize - 1) / maxPayloadSize) // round up
|
|
var frags []udpMessage
|
|
for off < len(fullPayload) {
|
|
payloadSize := len(fullPayload) - off
|
|
if payloadSize > maxPayloadSize {
|
|
payloadSize = maxPayloadSize
|
|
}
|
|
frag := m
|
|
frag.FragID = fragID
|
|
frag.FragCount = fragCount
|
|
frag.DataLen = uint16(payloadSize)
|
|
frag.Data = fullPayload[off : off+payloadSize]
|
|
frags = append(frags, frag)
|
|
off += payloadSize
|
|
fragID++
|
|
}
|
|
return frags
|
|
}
|
|
|
|
type defragger struct {
|
|
msgID uint16
|
|
frags []*udpMessage
|
|
count uint8
|
|
}
|
|
|
|
func (d *defragger) Feed(m udpMessage) *udpMessage {
|
|
if m.FragCount <= 1 {
|
|
return &m
|
|
}
|
|
if m.FragID >= m.FragCount {
|
|
// wtf is this?
|
|
return nil
|
|
}
|
|
if m.MsgID != d.msgID {
|
|
// new message, clear previous state
|
|
d.msgID = m.MsgID
|
|
d.frags = make([]*udpMessage, m.FragCount)
|
|
d.count = 1
|
|
d.frags[m.FragID] = &m
|
|
} else if d.frags[m.FragID] == nil {
|
|
d.frags[m.FragID] = &m
|
|
d.count++
|
|
if int(d.count) == len(d.frags) {
|
|
// all fragments received, assemble
|
|
var data []byte
|
|
for _, frag := range d.frags {
|
|
data = append(data, frag.Data...)
|
|
}
|
|
m.DataLen = uint16(len(data))
|
|
m.Data = data
|
|
m.FragID = 0
|
|
m.FragCount = 1
|
|
return &m
|
|
}
|
|
}
|
|
return nil
|
|
}
|