cert-checker: use config log level and handle nil mariadb response (#6066)

- Fix cert-checker to use the syslog and stdout logging facilities it
reads from the config file instead of having them hard-coded to zero.
- Fix cert-checker to handle a nil response from mariadb if no records
are found.
- Fix comment in log.go to correctly describe when the initialize function
and therefore default values would be used.

Fixes #6067

cmd/cert-checker/main.go

@@ -4,7 +4,9 @@ import (
 	"bytes"
 	"context"
 	"crypto/x509"
+	"database/sql"
 	"encoding/json"
+	"errors"
 	"flag"
 	"fmt"
 	"log/syslog"
@@ -80,7 +82,7 @@ type reportEntry struct {
 // out the saDbMap implementation.
 type certDB interface {
 	Select(i interface{}, query string, args ...interface{}) ([]interface{}, error)
-	SelectInt(query string, args ...interface{}) (int64, error)
+	SelectNullInt(query string, args ...interface{}) (sql.NullInt64, error)
 }
 
 type certChecker struct {
@@ -118,13 +120,19 @@ func (c *certChecker) getCerts(unexpiredOnly bool) error {
 		args["now"] = c.clock.Now()
 	}
 
-	initialID, err := c.dbMap.SelectInt(
+	sni, err := c.dbMap.SelectNullInt(
 		"SELECT MIN(id) FROM certificates WHERE issued >= :issued AND expires >= :now",
 		args,
 	)
 	if err != nil {
 		return err
 	}
+	if !sni.Valid {
+		// a nil response was returned by the DB, so return error and fail
+		return errors.New("the SELECT query resulted in a NULL response from the DB")
+	}
+
+	initialID := sni.Int64
 	if initialID > 0 {
 		// decrement the initial ID so that we select below as we aren't using >=
 		initialID -= 1
@@ -368,8 +376,12 @@ func main() {
 	syslogger, err := syslog.Dial("", "", syslog.LOG_INFO|syslog.LOG_LOCAL0, "")
 	cmd.FailOnError(err, "Failed to dial syslog")
 
-	logger, err := blog.New(syslogger, 0, 0)
-	cmd.FailOnError(err, "Failed to construct logger")
+	syslogLevel := int(syslog.LOG_INFO)
+	if config.Syslog.SyslogLevel != 0 {
+		syslogLevel = config.Syslog.SyslogLevel
+	}
+	logger, err := blog.New(syslogger, config.Syslog.StdoutLevel, syslogLevel)
+	cmd.FailOnError(err, "Could not connect to Syslog")
 
 	err = blog.Set(logger)
 	cmd.FailOnError(err, "Failed to set audit logger")

cmd/cert-checker/main_test.go

@@ -9,6 +9,7 @@ import (
 	"crypto/rsa"
 	"crypto/x509"
 	"crypto/x509/pkix"
+	"database/sql"
 	"encoding/asn1"
 	"encoding/pem"
 	"io/ioutil"
@@ -380,8 +381,12 @@ type mismatchedCountDB struct{}
 // `getCerts` calls `SelectInt` first to determine how many rows there are
 // matching the `getCertsCountQuery` criteria. For this mock we return
 // a non-zero number
-func (db mismatchedCountDB) SelectInt(_ string, _ ...interface{}) (int64, error) {
-	return 99999, nil
+func (db mismatchedCountDB) SelectNullInt(_ string, _ ...interface{}) (sql.NullInt64, error) {
+	return sql.NullInt64{
+			Int64: 99999,
+			Valid: true,
+		},
+		nil
 }
 
 // `getCerts` then calls `Select` to retrieve the Certificate rows. We pull
@@ -422,6 +427,33 @@ func TestGetCertsEmptyResults(t *testing.T) {
 	test.AssertNotError(t, err, "Failed to retrieve certificates")
 }
 
+// emptyDB is a certDB object with methods used for testing that 'null'
+// responses received from the database are handled properly.
+type emptyDB struct {
+	certDB
+}
+
+// SelectNullInt is a method that returns a false sql.NullInt64 struct to
+// mock a null DB response
+func (db emptyDB) SelectNullInt(_ string, _ ...interface{}) (sql.NullInt64, error) {
+	return sql.NullInt64{Valid: false},
+		nil
+}
+
+// TestGetCertsNullResults tests that a null response from the database will
+// be handled properly. It uses the emptyDB above to mock the response
+// expected if the DB finds no certificates to match the SELECT query and
+// should return an error.
+func TestGetCertsNullResults(t *testing.T) {
+	saDbMap, err := sa.NewDbMap(vars.DBConnSA, sa.DbSettings{})
+	test.AssertNotError(t, err, "Couldn't connect to database")
+	checker := newChecker(saDbMap, clock.NewFake(), pa, kp, time.Hour, testValidityDurations)
+	checker.dbMap = emptyDB{}
+
+	err = checker.getCerts(false)
+	test.AssertError(t, err, "Should have gotten error from empty DB")
+}
+
 func TestSaveReport(t *testing.T) {
 	r := report{
 		begin:     time.Time{},

log/log.go

@@ -65,10 +65,9 @@ func New(log *syslog.Writer, stdoutLogLevel int, syslogLogLevel int) (Logger, er
 	}, nil
 }
 
-// initialize should only be used in unit tests.
+// initialize is used in unit tests and called by `Get` before the logger
+// is fully set up.
 func initialize() {
-	// defaultPriority is never used because we always use specific priority-based
-	// logging methods.
 	const defaultPriority = syslog.LOG_INFO | syslog.LOG_LOCAL0
 	syslogger, err := syslog.Dial("", "", defaultPriority, "test")
 	if err != nil {