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https://github.com/ossrs/srs.git
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5a420ece3b
01. Support GB config as StreamCaster. 02. Support disable GB by --gb28181=off. 03. Add utests for SIP examples. 04. Wireshark plugin to decode TCP/9000 as rtp.rfc4571 05. Support MPEGPS program stream codec. 06. Add utest for PS stream codec. 07. Decode MPEGPS packet stream. 08. Carry RTP and PS packet as helper in PS message. 09. Support recover from error mode. 10. Support process by a pack of PS/TS messages. 11. Add statistic for recovered and msgs dropped. 12. Recover from err position fastly. 13. Define state machine for GB session. 14. Bind context to GB session. 15. Re-invite when media disconnected. 16. Update GitHub actions with GB28181. 17. Support parse CANDIDATE by env or pip. 18. Support mux GB28181 to RTMP. 19. Support regression test by srs-bench.
61 lines
1.8 KiB
Go
61 lines
1.8 KiB
Go
package ws
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import (
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"encoding/binary"
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)
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// Cipher applies XOR cipher to the payload using mask.
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// Offset is used to cipher chunked data (e.g. in io.Reader implementations).
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//
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// To convert masked data into unmasked data, or vice versa, the following
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// algorithm is applied. The same algorithm applies regardless of the
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// direction of the translation, e.g., the same steps are applied to
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// mask the data as to unmask the data.
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func Cipher(payload []byte, mask [4]byte, offset int) {
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n := len(payload)
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if n < 8 {
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for i := 0; i < n; i++ {
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payload[i] ^= mask[(offset+i)%4]
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}
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return
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}
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// Calculate position in mask due to previously processed bytes number.
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mpos := offset % 4
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// Count number of bytes will processed one by one from the beginning of payload.
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ln := remain[mpos]
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// Count number of bytes will processed one by one from the end of payload.
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// This is done to process payload by 8 bytes in each iteration of main loop.
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rn := (n - ln) % 8
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for i := 0; i < ln; i++ {
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payload[i] ^= mask[(mpos+i)%4]
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}
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for i := n - rn; i < n; i++ {
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payload[i] ^= mask[(mpos+i)%4]
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}
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// NOTE: we use here binary.LittleEndian regardless of what is real
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// endianess on machine is. To do so, we have to use binary.LittleEndian in
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// the masking loop below as well.
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var (
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m = binary.LittleEndian.Uint32(mask[:])
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m2 = uint64(m)<<32 | uint64(m)
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)
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// Skip already processed right part.
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// Get number of uint64 parts remaining to process.
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n = (n - ln - rn) >> 3
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for i := 0; i < n; i++ {
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var (
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j = ln + (i << 3)
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chunk = payload[j : j+8]
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)
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p := binary.LittleEndian.Uint64(chunk)
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p = p ^ m2
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binary.LittleEndian.PutUint64(chunk, p)
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}
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}
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// remain maps position in masking key [0,4) to number
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// of bytes that need to be processed manually inside Cipher().
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var remain = [4]int{0, 3, 2, 1}
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