refactor(geoip): ParseConf takes a string, not a file path

The old ParseConf opened the file itself, which the name did not
convey. Now it parses the config text directly, matching
encoding/json.Unmarshal-style conventions: callers read the file (or
source the string however they like) and pass it in. Also introduce
errors.ErrMissingCredentials for the credential-missing case so callers
can branch on it.

cmd/check-ip/main.go

@@ -104,7 +104,11 @@ func main() {
 		}
 	}
 	if cfg.GeoIPConfPath != "" {
-		conf, err := geoip.ParseConf(cfg.GeoIPConfPath)
+		data, err := os.ReadFile(cfg.GeoIPConfPath)
+		if err != nil {
+			log.Fatalf("geoip-conf: %v", err)
+		}
+		conf, err := geoip.ParseConf(string(data))
 		if err != nil {
 			log.Fatalf("geoip-conf: %v", err)
 		}

net/geoip/cmd/geoip-update/main.go

@@ -17,7 +17,12 @@ func main() {
 	freshDays := flag.Int("fresh-days", 3, "skip download if file is younger than N days")
 	flag.Parse()
 
-	cfg, err := geoip.ParseConf(*configPath)
+	data, err := os.ReadFile(*configPath)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "error: %v\n", err)
+		os.Exit(1)
+	}
+	cfg, err := geoip.ParseConf(string(data))
 	if err != nil {
 		fmt.Fprintf(os.Stderr, "error: %v\n", err)
 		os.Exit(1)

net/geoip/conf.go

@@ -2,8 +2,7 @@ package geoip
 
 import (
 	"bufio"
-	"fmt"
+	"errors"
-	"os"
 	"strings"
 )
 
@@ -15,18 +14,16 @@ type Conf struct {
 	DatabaseDirectory string
 }
 
-// ParseConf reads a geoipupdate-style config file (whitespace-separated
+// ErrMissingCredentials is returned by ParseConf when AccountID or LicenseKey
-// key/value pairs, # comments). Compatible with GeoIP.conf files used by
+// is absent from the input.
-// the official geoipupdate tool.
+var ErrMissingCredentials = errors.New("AccountID and LicenseKey are required")
-func ParseConf(path string) (*Conf, error) {
-	f, err := os.Open(path)
-	if err != nil {
-		return nil, err
-	}
-	defer f.Close()
 
+// ParseConf parses a geoipupdate-style config (whitespace-separated key/value
+// pairs, # comments). Compatible with GeoIP.conf files used by the official
+// geoipupdate tool.
+func ParseConf(s string) (*Conf, error) {
 	kv := make(map[string]string)
-	scanner := bufio.NewScanner(f)
+	scanner := bufio.NewScanner(strings.NewReader(s))
 	for scanner.Scan() {
 		line := strings.TrimSpace(scanner.Text())
 		if line == "" || strings.HasPrefix(line, "#") {
@@ -45,7 +42,7 @@ func ParseConf(path string) (*Conf, error) {
 		DatabaseDirectory: kv["DatabaseDirectory"],
 	}
 	if c.AccountID == "" || c.LicenseKey == "" {
-		return nil, fmt.Errorf("AccountID and LicenseKey are required in %s", path)
+		return nil, ErrMissingCredentials
 	}
 	if ids := kv["EditionIDs"]; ids != "" {
 		c.EditionIDs = strings.Fields(ids)

net/geoip/geoip_integration_test.go

@@ -31,8 +31,8 @@ func geoipConf(t *testing.T) *geoip.Conf {
 	dir, _ := filepath.Abs(".")
 	for {
 		p := filepath.Join(dir, "GeoIP.conf")
-		if _, err := os.Stat(p); err == nil {
+		if data, err := os.ReadFile(p); err == nil {
-			cfg, err := geoip.ParseConf(p)
+			cfg, err := geoip.ParseConf(string(data))
 			if err != nil {
 				t.Fatalf("GeoIP.conf: %v", err)
 			}