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query_logging_resolver.go
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/
query_logging_resolver.go
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package resolver
import (
"fmt"
"time"
"github.com/0xERR0R/blocky/config"
"github.com/0xERR0R/blocky/model"
"github.com/0xERR0R/blocky/querylog"
"github.com/0xERR0R/blocky/util"
"github.com/avast/retry-go/v4"
"github.com/miekg/dns"
)
const (
cleanUpRunPeriod = 12 * time.Hour
queryLoggingResolverPrefix = "query_logging_resolver"
logChanCap = 1000
defaultFlushPeriod = 30 * time.Second
)
// QueryLoggingResolver writes query information (question, answer, duration, ...)
type QueryLoggingResolver struct {
NextResolver
target string
logRetentionDays uint64
logChan chan *querylog.LogEntry
writer querylog.Writer
logType config.QueryLogType
fields []config.QueryLogField
}
// NewQueryLoggingResolver returns a new resolver instance
func NewQueryLoggingResolver(cfg config.QueryLogConfig) ChainedResolver {
var writer querylog.Writer
logType := cfg.Type
err := retry.Do(
func() error {
var err error
switch logType {
case config.QueryLogTypeCsv:
writer, err = querylog.NewCSVWriter(cfg.Target, false, cfg.LogRetentionDays)
case config.QueryLogTypeCsvClient:
writer, err = querylog.NewCSVWriter(cfg.Target, true, cfg.LogRetentionDays)
case config.QueryLogTypeMysql:
writer, err = querylog.NewDatabaseWriter("mysql", cfg.Target, cfg.LogRetentionDays, defaultFlushPeriod)
case config.QueryLogTypePostgresql:
writer, err = querylog.NewDatabaseWriter("postgresql", cfg.Target, cfg.LogRetentionDays, defaultFlushPeriod)
case config.QueryLogTypeConsole:
writer = querylog.NewLoggerWriter()
case config.QueryLogTypeNone:
writer = querylog.NewNoneWriter()
}
return err
},
retry.Attempts(uint(cfg.CreationAttempts)),
retry.DelayType(retry.FixedDelay),
retry.Delay(time.Duration(cfg.CreationCooldown)),
retry.OnRetry(func(n uint, err error) {
logger(queryLoggingResolverPrefix).Warnf("Error occurred on query writer creation, "+
"retry attempt %d/%d: %v", n+1, cfg.CreationAttempts, err)
}))
if err != nil {
logger(queryLoggingResolverPrefix).Error("can't create query log writer, using console as fallback: ", err)
writer = querylog.NewLoggerWriter()
logType = config.QueryLogTypeConsole
}
logChan := make(chan *querylog.LogEntry, logChanCap)
resolver := QueryLoggingResolver{
target: cfg.Target,
logRetentionDays: cfg.LogRetentionDays,
logChan: logChan,
writer: writer,
logType: logType,
fields: resolveQueryLogFields(cfg),
}
go resolver.writeLog()
if cfg.LogRetentionDays > 0 {
go resolver.periodicCleanUp()
}
return &resolver
}
func resolveQueryLogFields(cfg config.QueryLogConfig) []config.QueryLogField {
var fields []config.QueryLogField
if len(cfg.Fields) == 0 {
// no fields defined, use all fields as fallback
for _, v := range config.QueryLogFieldNames() {
qlt, err := config.ParseQueryLogField(v)
util.LogOnError("ignoring unknown query log field", err)
fields = append(fields, qlt)
}
} else {
fields = cfg.Fields
}
return fields
}
// triggers periodically cleanup of old log files
func (r *QueryLoggingResolver) periodicCleanUp() {
ticker := time.NewTicker(cleanUpRunPeriod)
defer ticker.Stop()
for {
<-ticker.C
r.doCleanUp()
}
}
func (r *QueryLoggingResolver) doCleanUp() {
r.writer.CleanUp()
}
// Resolve logs the query, duration and the result
func (r *QueryLoggingResolver) Resolve(request *model.Request) (*model.Response, error) {
logger := withPrefix(request.Log, queryLoggingResolverPrefix)
start := time.Now()
resp, err := r.next.Resolve(request)
duration := time.Since(start).Milliseconds()
if err == nil {
select {
case r.logChan <- r.createLogEntry(request, resp, start, duration):
default:
logger.Error("query log writer is too slow, log entry will be dropped")
}
}
return resp, err
}
func (r *QueryLoggingResolver) createLogEntry(request *model.Request, response *model.Response,
start time.Time, durationMs int64) *querylog.LogEntry {
entry := querylog.LogEntry{
Start: start,
ClientIP: "0.0.0.0",
ClientNames: []string{"none"},
}
for _, f := range r.fields {
switch f {
case config.QueryLogFieldClientIP:
entry.ClientIP = request.ClientIP.String()
case config.QueryLogFieldClientName:
entry.ClientNames = request.ClientNames
case config.QueryLogFieldResponseReason:
entry.ResponseReason = response.Reason
entry.ResponseType = response.RType.String()
entry.ResponseCode = dns.RcodeToString[response.Res.Rcode]
case config.QueryLogFieldResponseAnswer:
entry.Answer = util.AnswerToString(response.Res.Answer)
case config.QueryLogFieldQuestion:
entry.QuestionName = request.Req.Question[0].Name
entry.QuestionType = dns.TypeToString[request.Req.Question[0].Qtype]
case config.QueryLogFieldDuration:
entry.DurationMs = durationMs
}
}
return &entry
}
// write entry: if log directory is configured, write to log file
func (r *QueryLoggingResolver) writeLog() {
for logEntry := range r.logChan {
start := time.Now()
r.writer.Write(logEntry)
halfCap := cap(r.logChan) / 2 //nolint:gomnd
// if log channel is > 50% full, this could be a problem with slow writer (external storage over network etc.)
if len(r.logChan) > halfCap {
logger(queryLoggingResolverPrefix).WithField("channel_len",
len(r.logChan)).Warnf("query log writer is too slow, write duration: %d ms", time.Since(start).Milliseconds())
}
}
}
// Configuration returns the current resolver configuration
func (r *QueryLoggingResolver) Configuration() (result []string) {
result = append(result, fmt.Sprintf("type: \"%s\"", r.logType))
result = append(result, fmt.Sprintf("target: \"%s\"", r.target))
result = append(result, fmt.Sprintf("logRetentionDays: %d", r.logRetentionDays))
result = append(result, fmt.Sprintf("fields: %s", r.fields))
return
}