82 lines
2.0 KiB
Go
82 lines
2.0 KiB
Go
package ingest
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import (
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"crypto/sha256"
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"encoding/binary"
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"strings"
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)
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// 以下 Feistel + base62 编码与后台 internal/pkg/hashid 完全一致，
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// 仅实现编码侧（爬虫只需把品牌数字主键编码为 brand_uid 上送，无需解码）。
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// 盐值必须 == 后台 HASHID_SECRET，否则生成的 brand_uid 后台解码不出正确主键。
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const (
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hidAlphabet = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
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hidBase = 62
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hidMinLen = 8
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)
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var hidKeys [4]uint32
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// InitHashID 用与后台 HASHID_SECRET 相同的盐值初始化编码密钥。
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// secret 为空时回落后台内置默认盐（仅防顺序枚举，不安全）。
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func InitHashID(secret string) {
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if secret == "" {
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secret = "fashion-archive-default-salt-change-me"
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}
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h := sha256.Sum256([]byte(secret))
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for i := 0; i < 4; i++ {
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hidKeys[i] = binary.BigEndian.Uint32(h[i*4 : i*4+4])
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}
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}
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// hidFeistel 32-bit 平衡 Feistel 网络，encrypt=true 加密。
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func hidFeistel(v uint32, encrypt bool) uint32 {
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const rounds = 8
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l, r := uint16(v>>16), uint16(v&0xffff)
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for i := 0; i < rounds; i++ {
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idx := i
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if !encrypt {
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idx = rounds - 1 - i
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}
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round := func(h uint16) uint16 {
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f := uint32(h)*0x9E3779B1 + hidKeys[idx%4]
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return uint16((f ^ (f >> 16)) & 0xffff)
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}
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if encrypt {
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nl, nr := r, uint16(l)^round(r)
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l, r = nl, nr
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} else {
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nl, nr := uint16(l)^round(l), l
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l, r = nl, nr
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}
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}
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return uint32(l)<<16 | uint32(r)
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}
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func encodeNum(n uint32) string {
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x := hidFeistel(n, true)
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var sb strings.Builder
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for x > 0 {
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sb.WriteByte(hidAlphabet[x%hidBase])
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x /= hidBase
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}
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if sb.Len() == 0 {
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sb.WriteByte(hidAlphabet[0])
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}
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runes := []rune(sb.String())
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for i, j := 0, len(runes)-1; i < j; i, j = i+1, j-1 {
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runes[i], runes[j] = runes[j], runes[i]
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}
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out := string(runes)
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if len(out) < hidMinLen {
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out = strings.Repeat("0", hidMinLen-len(out)) + out
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}
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return out
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}
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// EncodeBrand 把品牌数字主键编码为 hashid 串（与后台 brand_uid 同算法）。
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func EncodeBrand(id uint32) string {
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return encodeNum(id)
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}
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