Documentation
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Overview ¶
Package hashprefix defines a storage of hashes of domain names used for filtering and serving TXT records with domain-name hashes.
Index ¶
Constants ¶
const ( // PrefixLen is the length of the hash prefix of the filtered hostname. PrefixLen = 2 // PrefixEncLen is the encoded length of the hash prefix. Two text // bytes per one binary byte. PrefixEncLen = PrefixLen * 2 )
Hash and hash part length constants.
const IDPrefix = "filters/hashprefix"
IDPrefix is a common prefix for cache IDs, logging, and refreshes of hashprefix filters.
TODO(a.garipov): Consider better names.
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type Filter ¶
type Filter struct {
// contains filtered or unexported fields
}
Filter is a filter that matches hosts by their hashes based on a hash-prefix table. It should be initially refreshed with Filter.RefreshInitial.
func NewFilter ¶
func NewFilter(c *FilterConfig) (f *Filter, err error)
NewFilter returns a new hash-prefix filter. It also adds the caches with IDs [FilterListIDAdultBlocking], [FilterListIDSafeBrowsing], and [FilterListIDNewRegDomains] to the cache manager. c must not be nil.
func (*Filter) FilterRequest ¶
func (f *Filter) FilterRequest( ctx context.Context, req *internal.Request, ) (r internal.Result, err error)
FilterRequest implements the internal.RequestFilter interface for *Filter. It modifies the request or response if host matches f.
func (*Filter) ID ¶
ID implements the internal.RequestFilter interface for *Filter.
func (*Filter) Refresh ¶
Refresh implements the agdservice.Refresher interface for *Filter.
type FilterConfig ¶
type FilterConfig struct {
// Logger is used for logging the operation of the filter.
Logger *slog.Logger
// Cloner is used to clone messages taken from filtering-result cache.
Cloner *dnsmsg.Cloner
// CacheManager is the global cache manager. CacheManager must not be nil.
CacheManager agdcache.Manager
// Hashes are the hostname hashes for this filter.
Hashes *Storage
// URL is the URL used to update the filter.
URL *url.URL
// ErrColl is used to collect non-critical and rare errors.
ErrColl errcoll.Interface
// Metrics are the metrics for the hashprefix filter.
//
// TODO(a.garipov): Create a separate interface to also handle the
// hashprefix-specific metrics.
Metrics internal.Metrics
// ID is the ID of this hash storage for logging and error reporting.
ID internal.ID
// CachePath is the path to the file containing the cached filtered
// hostnames, one per line.
CachePath string
// ReplacementHost is the replacement host for this filter. Queries matched
// by the filter receive a response with the IP addresses of this host. If
// ReplacementHost contains a valid IP, that IP is used. Otherwise, it
// should be a valid domain name.
ReplacementHost string
// Staleness is the time after which a file is considered stale.
Staleness time.Duration
// CacheTTL is the time-to-live value used to cache the results of the
// filter.
//
// TODO(a.garipov): Currently unused. See AGDNS-398.
CacheTTL time.Duration
// RefreshTimeout is the timeout for the filter update operation.
RefreshTimeout time.Duration
// CacheCount is the count of the elements in the filter's result cache.
CacheCount int
// MaxSize is the maximum size of the downloadable rule-list.
MaxSize datasize.ByteSize
}
FilterConfig is the hash-prefix filter configuration structure.
type Matcher ¶
type Matcher struct {
// contains filtered or unexported fields
}
Matcher is a hash-prefix matcher that uses the hash-prefix storages as the source of its data.
func NewMatcher ¶
NewMatcher returns a new hash-prefix matcher. storages is a mapping of domain-name suffixes to the storage containing hashes for this domain. If storages is empty, m.MatchByPrefix always returns nil, false, and nil.
func (*Matcher) MatchByPrefix ¶
func (m *Matcher) MatchByPrefix( _ context.Context, host string, ) (hashes []string, matched bool, err error)
MatchByPrefix implements the [filter.HashMatcher] interface for *Matcher. It returns the matched hashes if the host matched one of the domain names in m's storages.
TODO(a.garipov): Use the context for logging etc.
type Prefix ¶
Prefix is the type of the SHA256 hash prefix used to match against the domain-name database.
type Storage ¶
type Storage struct {
// contains filtered or unexported fields
}
Storage stores hashes of the filtered hostnames. All methods are safe for concurrent use.
TODO(a.garipov): See if we could unexport this.
func NewStorage ¶
NewStorage returns a new hash storage containing hashes of the domain names listed in hostnames, one domain name per line, requirements are described in Storage.Reset. Empty string causes no errors.
func (*Storage) Hashes ¶
Hashes returns all hashes starting with the given prefixes, if any. The resulting slice shares storage for all underlying strings.
TODO(a.garipov): This currently doesn't take duplicates into account.
Source Files