53 lines
1.8 KiB
Go
53 lines
1.8 KiB
Go
package qtls
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import (
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"crypto/tls"
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"fmt"
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"unsafe"
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)
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//go:linkname cipherSuitesTLS13 crypto/tls.cipherSuitesTLS13
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var cipherSuitesTLS13 []unsafe.Pointer
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//go:linkname defaultCipherSuitesTLS13 crypto/tls.defaultCipherSuitesTLS13
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var defaultCipherSuitesTLS13 []uint16
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//go:linkname defaultCipherSuitesTLS13NoAES crypto/tls.defaultCipherSuitesTLS13NoAES
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var defaultCipherSuitesTLS13NoAES []uint16
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var cipherSuitesModified bool
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// SetCipherSuite modifies the cipherSuiteTLS13 slice of cipher suites inside qtls
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// such that it only contains the cipher suite with the chosen id.
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// The reset function returned resets them back to the original value.
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func SetCipherSuite(id uint16) (reset func()) {
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if cipherSuitesModified {
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panic("cipher suites modified multiple times without resetting")
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}
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cipherSuitesModified = true
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origCipherSuitesTLS13 := append([]unsafe.Pointer{}, cipherSuitesTLS13...)
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origDefaultCipherSuitesTLS13 := append([]uint16{}, defaultCipherSuitesTLS13...)
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origDefaultCipherSuitesTLS13NoAES := append([]uint16{}, defaultCipherSuitesTLS13NoAES...)
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// The order is given by the order of the slice elements in cipherSuitesTLS13 in qtls.
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switch id {
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case tls.TLS_AES_128_GCM_SHA256:
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cipherSuitesTLS13 = cipherSuitesTLS13[:1]
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case tls.TLS_CHACHA20_POLY1305_SHA256:
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cipherSuitesTLS13 = cipherSuitesTLS13[1:2]
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case tls.TLS_AES_256_GCM_SHA384:
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cipherSuitesTLS13 = cipherSuitesTLS13[2:]
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default:
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panic(fmt.Sprintf("unexpected cipher suite: %d", id))
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}
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defaultCipherSuitesTLS13 = []uint16{id}
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defaultCipherSuitesTLS13NoAES = []uint16{id}
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return func() {
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cipherSuitesTLS13 = origCipherSuitesTLS13
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defaultCipherSuitesTLS13 = origDefaultCipherSuitesTLS13
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defaultCipherSuitesTLS13NoAES = origDefaultCipherSuitesTLS13NoAES
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cipherSuitesModified = false
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}
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}
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