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f40f94670e
to compress the entire IMAP connection. tested with thunderbird, meli, k9, ios mail. the initial implementation had interoperability issues with some of these clients: if they write the deflate stream and flush in "partial mode", the go stdlib flate reader does not return any data (until there is an explicit zero-length "sync flush" block, or until the history/sliding window is full), blocking progress, resulting in clients closing the seemingly stuck connection after considering the connection timed out. this includes a coy of the flate package with a new reader that returns partially flushed blocks earlier. this also adds imap trace logging to imapclient.Conn, which was useful for debugging.
98 lines
3.6 KiB
Go
98 lines
3.6 KiB
Go
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package flate
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const (
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// 2 bits: type 0 = literal 1=EOF 2=Match 3=Unused
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// 8 bits: xlength = length - MIN_MATCH_LENGTH
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// 22 bits xoffset = offset - MIN_OFFSET_SIZE, or literal
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lengthShift = 22
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offsetMask = 1<<lengthShift - 1
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typeMask = 3 << 30
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literalType = 0 << 30
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matchType = 1 << 30
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)
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// The length code for length X (MIN_MATCH_LENGTH <= X <= MAX_MATCH_LENGTH)
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// is lengthCodes[length - MIN_MATCH_LENGTH]
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var lengthCodes = [...]uint32{
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0, 1, 2, 3, 4, 5, 6, 7, 8, 8,
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9, 9, 10, 10, 11, 11, 12, 12, 12, 12,
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13, 13, 13, 13, 14, 14, 14, 14, 15, 15,
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15, 15, 16, 16, 16, 16, 16, 16, 16, 16,
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17, 17, 17, 17, 17, 17, 17, 17, 18, 18,
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18, 18, 18, 18, 18, 18, 19, 19, 19, 19,
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19, 19, 19, 19, 20, 20, 20, 20, 20, 20,
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20, 20, 20, 20, 20, 20, 20, 20, 20, 20,
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21, 21, 21, 21, 21, 21, 21, 21, 21, 21,
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21, 21, 21, 21, 21, 21, 22, 22, 22, 22,
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22, 22, 22, 22, 22, 22, 22, 22, 22, 22,
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22, 22, 23, 23, 23, 23, 23, 23, 23, 23,
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23, 23, 23, 23, 23, 23, 23, 23, 24, 24,
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24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
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24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
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24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
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25, 25, 25, 25, 25, 25, 25, 25, 25, 25,
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25, 25, 25, 25, 25, 25, 25, 25, 25, 25,
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25, 25, 25, 25, 25, 25, 25, 25, 25, 25,
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25, 25, 26, 26, 26, 26, 26, 26, 26, 26,
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26, 26, 26, 26, 26, 26, 26, 26, 26, 26,
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26, 26, 26, 26, 26, 26, 26, 26, 26, 26,
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26, 26, 26, 26, 27, 27, 27, 27, 27, 27,
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27, 27, 27, 27, 27, 27, 27, 27, 27, 27,
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27, 27, 27, 27, 27, 27, 27, 27, 27, 27,
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27, 27, 27, 27, 27, 28,
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}
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var offsetCodes = [...]uint32{
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0, 1, 2, 3, 4, 4, 5, 5, 6, 6, 6, 6, 7, 7, 7, 7,
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8, 8, 8, 8, 8, 8, 8, 8, 9, 9, 9, 9, 9, 9, 9, 9,
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10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10,
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11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11,
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12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12,
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12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12,
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13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13,
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13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13,
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14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14,
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14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14,
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14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14,
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14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14,
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15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,
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15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,
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15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,
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15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,
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}
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type token uint32
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// Convert a literal into a literal token.
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func literalToken(literal uint32) token { return token(literalType + literal) }
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// Convert a < xlength, xoffset > pair into a match token.
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func matchToken(xlength uint32, xoffset uint32) token {
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return token(matchType + xlength<<lengthShift + xoffset)
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}
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// Returns the literal of a literal token.
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func (t token) literal() uint32 { return uint32(t - literalType) }
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// Returns the extra offset of a match token.
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func (t token) offset() uint32 { return uint32(t) & offsetMask }
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func (t token) length() uint32 { return uint32((t - matchType) >> lengthShift) }
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func lengthCode(len uint32) uint32 { return lengthCodes[len] }
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// Returns the offset code corresponding to a specific offset.
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func offsetCode(off uint32) uint32 {
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if off < uint32(len(offsetCodes)) {
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return offsetCodes[off]
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}
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if off>>7 < uint32(len(offsetCodes)) {
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return offsetCodes[off>>7] + 14
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}
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return offsetCodes[off>>14] + 28
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}
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