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echo/middleware/util.go

104 lines
2.7 KiB
Go

// SPDX-License-Identifier: MIT
// SPDX-FileCopyrightText: © 2015 LabStack LLC and Echo contributors
package middleware
import (
"bufio"
"crypto/rand"
"io"
"strings"
"sync"
)
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
}
// 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)
func randomString(length uint8) string {
reader := randomReaderPool.Get().(*bufio.Reader)
defer randomReaderPool.Put(reader)
b := make([]byte, length)
r := make([]byte, length+(length/4)) // perf: avoid read from rand.Reader many times
var i uint8 = 0
// security note:
// we can't just simply do b[i]=randomStringCharset[rb%len(randomStringCharset)],
// len(len(randomStringCharset)) is 52, and rb is [0, 255], 256 = 52 * 4 + 48.
// make the first 48 characters more possibly to be generated then others.
// So we have to skip bytes when rb > randomStringMaxByte
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)
}
}
}
}