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echo/middleware/util.go

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2.8 KiB
Go
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package middleware
import (
"bufio"
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"crypto/rand"
"io"
"strings"
"sync"
)
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const (
_ = int64(1 << (10 * iota)) // ignore first value by assigning to blank identifier
// KB is 1 KiloByte = 1024 bytes
KB
// MB is 1 Megabyte = 1_048_576 bytes
MB
// GB is 1 Gigabyte = 1_073_741_824 bytes
GB
// TB is 1 Terabyte = 1_099_511_627_776 bytes
TB
// PB is 1 Petabyte = 1_125_899_906_842_624 bytes
PB
// EB is 1 Exabyte = 1_152_921_504_606_847_000 bytes
EB
)
func matchScheme(domain, pattern string) bool {
didx := strings.Index(domain, ":")
pidx := strings.Index(pattern, ":")
return didx != -1 && pidx != -1 && domain[:didx] == pattern[:pidx]
}
// matchSubdomain compares authority with wildcard
func matchSubdomain(domain, pattern string) bool {
if !matchScheme(domain, pattern) {
return false
}
didx := strings.Index(domain, "://")
pidx := strings.Index(pattern, "://")
if didx == -1 || pidx == -1 {
return false
}
domAuth := domain[didx+3:]
// to avoid long loop by invalid long domain
if len(domAuth) > 253 {
return false
}
patAuth := pattern[pidx+3:]
domComp := strings.Split(domAuth, ".")
patComp := strings.Split(patAuth, ".")
for i := len(domComp)/2 - 1; i >= 0; i-- {
opp := len(domComp) - 1 - i
domComp[i], domComp[opp] = domComp[opp], domComp[i]
}
for i := len(patComp)/2 - 1; i >= 0; i-- {
opp := len(patComp) - 1 - i
patComp[i], patComp[opp] = patComp[opp], patComp[i]
}
for i, v := range domComp {
if len(patComp) <= i {
return false
}
p := patComp[i]
if p == "*" {
return true
}
if p != v {
return false
}
}
return false
}
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func createRandomStringGenerator(length uint8) func() string {
return func() string {
return randomString(length)
}
}
// https://tip.golang.org/doc/go1.19#:~:text=Read%20no%20longer%20buffers%20random%20data%20obtained%20from%20the%20operating%20system%20between%20calls
var randomReaderPool = sync.Pool{New: func() interface{} {
return bufio.NewReader(rand.Reader)
}}
const randomStringCharset = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
const randomStringCharsetLen = 52 // len(randomStringCharset)
const randomStringMaxByte = 255 - (256 % randomStringCharsetLen)
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func randomString(length uint8) string {
reader := randomReaderPool.Get().(*bufio.Reader)
defer randomReaderPool.Put(reader)
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b := make([]byte, length)
r := make([]byte, length+(length/4)) // perf: avoid read from rand.Reader many times
var i uint8 = 0
for {
_, err := io.ReadFull(reader, r)
if err != nil {
panic("unexpected error happened when reading from bufio.NewReader(crypto/rand.Reader)")
}
for _, rb := range r {
if rb > randomStringMaxByte {
// Skip this number to avoid bias.
continue
}
b[i] = randomStringCharset[rb%randomStringCharsetLen]
i++
if i == length {
return string(b)
}
}
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}
}