feat(11-03): re-authorize every Centrifugo subscribe through a namespace registry
- lighthouse: Registry of namespace authorizers (Result, Allowed, Denied), ParseChannel, ChannelID with PHP (int)-cast semantics (PHPInt, pinned by a php -r table test), FormatChannels, WithClientID/ClientID - centrifugo: ProxyHandler (constant-time X-Centrifugo-Secret, HTTP 200 generic deny, info [] on allow, presence allow/override merge, 64 KiB body cap) mounted as the ServerToServer subscribe route - README: proxy contract, registry and channel rules
This commit is contained in:
Jakub Zych
172
modules/lighthouse/channel.go
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172
modules/lighthouse/channel.go
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@@ -0,0 +1,172 @@
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package lighthouse
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import (
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"context"
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"math"
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"strconv"
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"strings"
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)
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// presencePrefix marks a presence channel.
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const presencePrefix = "presence:"
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// ParseChannel returns the authorizer namespace of channel, the WinterCMS
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// parseChannel rule:
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//
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// - a "presence:presence:" prefix yields "" (deny);
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// - one "presence:" prefix is stripped, and presence is reported true;
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// - more than three ":"-separated segments yield "" (deny);
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// - otherwise the namespace is the first segment.
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//
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// The lookup is byte-exact: no case folding or Unicode normalization.
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func ParseChannel(channel string) (namespace string, presence bool) {
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presence = strings.HasPrefix(channel, presencePrefix)
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if strings.HasPrefix(channel, presencePrefix+presencePrefix) {
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return "", presence
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}
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name := strings.TrimPrefix(channel, presencePrefix)
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parts := strings.Split(name, ":")
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if len(parts) > 3 {
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return "", presence
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}
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return parts[0], presence
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}
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// ChannelID returns segment 1 of channel (0 when it is missing) converted
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// with PHP's (int) cast, as the WinterCMS authorizers read
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// explode(':', $channel)[1]. "5abc" is 5, "abc" is 0, "1e3" is 1000, and
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// out-of-range values saturate. For "presence:collection:5" segment 1 is
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// "collection", so the id is 0.
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func ChannelID(channel string) int64 {
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parts := strings.SplitN(channel, ":", 3)
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if len(parts) < 2 {
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return 0
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}
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return PHPInt(parts[1])
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}
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// PHPInt converts s the way PHP 8's (int) cast converts a string: leading
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// whitespace and a sign are allowed, the longest numeric prefix (digits,
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// an optional fraction and exponent) is used, integers saturate at the
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// int64 bounds, and non-finite floats become 0.
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func PHPInt(s string) int64 {
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i := 0
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for i < len(s) && isPHPSpace(s[i]) {
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i++
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}
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start := i
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if i < len(s) && (s[i] == '+' || s[i] == '-') {
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i++
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}
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digitsStart := i
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for i < len(s) && isDigit(s[i]) {
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i++
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}
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intDigits := i - digitsStart
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isFloat := false
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if i < len(s) && s[i] == '.' {
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j := i + 1
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for j < len(s) && isDigit(s[j]) {
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j++
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}
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if intDigits > 0 || j > i+1 {
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isFloat = true
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i = j
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}
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}
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if intDigits == 0 && !isFloat {
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return 0
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}
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if i < len(s) && (s[i] == 'e' || s[i] == 'E') {
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j := i + 1
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if j < len(s) && (s[j] == '+' || s[j] == '-') {
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j++
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}
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k := j
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for k < len(s) && isDigit(s[k]) {
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k++
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}
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if k > j {
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isFloat = true
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i = k
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}
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}
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num := s[start:i]
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if !isFloat {
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n, err := strconv.ParseInt(num, 10, 64)
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if err != nil {
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if strings.HasPrefix(num, "-") {
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return math.MinInt64
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}
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return math.MaxInt64
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}
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return n
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}
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f, _ := strconv.ParseFloat(num, 64)
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switch {
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case math.IsInf(f, 0) || math.IsNaN(f):
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return 0
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case f >= math.MaxInt64:
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return math.MaxInt64
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case f <= math.MinInt64:
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return math.MinInt64
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default:
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return int64(f)
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}
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}
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func isPHPSpace(c byte) bool {
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return c == ' ' || c == '\t' || c == '\n' || c == '\r' || c == '\v' || c == '\f'
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}
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func isDigit(c byte) bool { return c >= '0' && c <= '9' }
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// FormatChannels lowercases each channel (ASCII, as PHP strtolower) and
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// prefixes lowercase(namespace)+":" unless the namespace is empty or the
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// channel already starts with that prefix.
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func FormatChannels(namespace string, channels []string) []string {
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out := make([]string, len(channels))
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prefix := ""
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if namespace != "" && namespace != "0" {
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prefix = asciiLower(namespace) + ":"
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}
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for i, ch := range channels {
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name := asciiLower(ch)
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if prefix != "" && !strings.HasPrefix(name, prefix) {
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name = prefix + name
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}
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out[i] = name
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}
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return out
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}
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func asciiLower(s string) string {
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b := []byte(s)
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for i, c := range b {
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if c >= 'A' && c <= 'Z' {
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b[i] = c + ('a' - 'A')
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}
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}
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return string(b)
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}
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type clientIDKey struct{}
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// WithClientID returns ctx carrying the realtime client id of a subscribe
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// request. Drivers call it before invoking an Authorizer.
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func WithClientID(ctx context.Context, id string) context.Context {
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if ctx == nil {
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ctx = context.Background()
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}
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return context.WithValue(ctx, clientIDKey{}, id)
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}
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// ClientID returns the realtime client id placed in ctx by the driver, or
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// "" outside a subscribe request.
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func ClientID(ctx context.Context) string {
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if ctx == nil {
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return ""
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}
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id, _ := ctx.Value(clientIDKey{}).(string)
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return id
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}
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