Store permanent errors

main.go

@@ -6,8 +6,10 @@ import (
 	"log"
 	"sort"
 	"time"
+	"bufio"
 	"errors"
 	"context"
+	"strconv"
 	"strings"
 	"net/url"
 	"crypto/x509"
@@ -21,6 +23,8 @@ import (
 var (
 	hosts     tofu.KnownHosts
 	hostsfile *tofu.HostWriter
+	predirs   map[string]*url.URL
+	perrors   map[string]PError
 )
 
 func xdgDataHome() string {
@@ -41,6 +45,154 @@ func init() {
 	if err != nil {
 		log.Fatal(err)
 	}
+
+	err = populatePRedirs()
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	err = populatePErrors()
+	if err != nil {
+		log.Fatal(err)
+	}
+}
+
+func populatePRedirs() error {
+	file, err := os.OpenFile(filepath.Join(xdgDataHome(), "konbata", "predirs"), os.O_RDONLY|os.O_CREATE, 0600)
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+	scanner := bufio.NewScanner(file)
+	predirs = make(map[string]*url.URL)
+	for scanner.Scan() {
+		urls := strings.Split(scanner.Text(), " ")
+		if len(urls) != 2 {
+			continue
+		}
+		url0, err := url.Parse(urls[0])
+		if err != nil {
+			continue
+		}
+		if url0.Scheme != "gemini" {
+			continue
+		}
+		url1, err := url.Parse(urls[1])
+		if err != nil {
+			continue
+		}
+		if url1.Scheme != "gemini" {
+			continue
+		}
+		predirs[url0.String()] = url1
+	}
+	return nil
+}
+
+func savePRedirs() error {
+	file, err := os.OpenFile(filepath.Join(xdgDataHome(), "konbata", "predirs"), os.O_WRONLY|os.O_CREATE, 0600)
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+	err = file.Truncate(0)
+	if err != nil {
+		return err
+	}
+	writer := bufio.NewWriter(file)
+	for url0, url1 := range predirs {
+		_, err = writer.WriteString(url0)
+		if err != nil {
+			return err
+		}
+		_, err = writer.WriteRune(' ')
+		if err != nil {
+			return err
+		}
+		_, err = writer.WriteString(url1.String())
+		if err != nil {
+			return err
+		}
+		_, err = writer.WriteRune('\n')
+		if err != nil {
+			return err
+		}
+	}
+	return writer.Flush()
+}
+
+func populatePErrors() error {
+	file, err := os.OpenFile(filepath.Join(xdgDataHome(), "konbata", "perrors"), os.O_RDONLY|os.O_CREATE, 0600)
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+	scanner := bufio.NewScanner(file)
+	perrors = make(map[string]PError)
+	unescaper := strings.NewReplacer("\\n", "\n", "\\\\", "\\")
+	for scanner.Scan() {
+		values := strings.SplitN(scanner.Text(), " ", 3)
+		if len(values) != 3 {
+			continue
+		}
+		url, err := url.Parse(values[0])
+		if err != nil {
+			continue
+		}
+		if url.Scheme != "gemini" {
+			continue
+		}
+		code, err := strconv.Atoi(values[1])
+		if err != nil {
+			continue
+		}
+		perrors[url.String()] = PError{
+			code: gemini.Status(code),
+			message: unescaper.Replace(values[2]),
+		}
+	}
+	return nil
+}
+
+func savePErrors() error {
+	file, err := os.OpenFile(filepath.Join(xdgDataHome(), "konbata", "perrors"), os.O_WRONLY|os.O_CREATE, 0600)
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+	err = file.Truncate(0)
+	if err != nil {
+		return err
+	}
+	writer := bufio.NewWriter(file)
+	escaper := strings.NewReplacer("\\", "\\\\", "\n", "\\n")
+	for url, perror := range perrors {
+		_, err = writer.WriteString(url)
+		if err != nil {
+			return err
+		}
+		_, err = writer.WriteRune(' ')
+		if err != nil {
+			return err
+		}
+		_, err = writer.WriteString(strconv.Itoa(int(perror.code)))
+		if err != nil {
+			return err
+		}
+		_, err = writer.WriteRune(' ')
+		if err != nil {
+			return err
+		}
+		_, err = escaper.WriteString(writer, perror.message)
+		if err != nil {
+			return err
+		}
+		_, err = writer.WriteRune('\n')
+		if err != nil {
+			return err
+		}
+	}
+	return writer.Flush()
 }
 
 func trustCertificate(hostname string, cert *x509.Certificate) error {
@@ -59,16 +211,50 @@ func trustCertificate(hostname string, cert *x509.Certificate) error {
 	return nil
 }
 
-func do(req *gemini.Request, via []*gemini.Request) (*gemini.Response, *gemini.Request, error) {
-	client := gemini.Client{
-		TrustCertificate: trustCertificate,
+func do(client gemini.Client, ctx context.Context, req *gemini.Request, via []*gemini.Request) (*gemini.Response, *gemini.Request, error) {
+	if target, exists := predirs[req.URL.String()]; exists {
+		via = append(via, req)
+		if len(via) > 5 {
+			return nil, req, errors.New("too many redirects")
+		}
+
+		redirect := *req
+		redirect.URL = target
+		return do(client, ctx, &redirect, via)
+	}
+	if perror, exists := perrors[req.URL.String()]; exists {
+		return nil, req, errors.New(fmt.Sprintf("%d %s", perror.code, perror.message))
 	}
-	ctx := context.Background()
 	resp, err := client.Do(ctx, req)
 	if err != nil {
 		return resp, req, err
 	}
 
+	if resp.Status == gemini.StatusPermanentRedirect {
+		target, err := url.Parse(resp.Meta)
+		if err != nil {
+			return resp, req, err
+		}
+		if target.Scheme != "gemini" && target.Scheme != "" {
+			return resp, req, errors.New(fmt.Sprintf("tried to redirect to scheme %s", target.Scheme))
+		}
+		target = req.URL.ResolveReference(target)
+		predirs[req.URL.String()] = target
+		err = savePRedirs()
+		if err != nil {
+			return resp, req, err
+		}
+	}
+	if resp.Status.Class() == gemini.StatusPermanentFailure {
+		perrors[req.URL.String()] = PError{
+			code: resp.Status,
+			message: resp.Meta,
+		}
+		err = savePErrors()
+		if err != nil {
+			return resp, req, err
+		}
+	}
 	if resp.Status.Class() == gemini.StatusRedirect {
 		via = append(via, req)
 		if len(via) > 5 {
@@ -85,7 +271,10 @@ func do(req *gemini.Request, via []*gemini.Request) (*gemini.Response, *gemini.R
 		target = req.URL.ResolveReference(target)
 		redirect := *req
 		redirect.URL = target
-		return do(&redirect, via)
+		return do(client, ctx, &redirect, via)
+	}
+	if resp.Status.Class() != gemini.StatusSuccess {
+		return resp, req, errors.New(fmt.Sprintf("%d %s", resp.Status, resp.Meta))
 	}
 
 	return resp, req, err
@@ -106,15 +295,16 @@ func main() {
 		log.Fatal(err)
 	}
 
-	resp, req, err := do(req, nil)
+	client := gemini.Client{
+		TrustCertificate: trustCertificate,
+	}
+	ctx := context.Background()
+	resp, req, err := do(client, ctx, req, nil)
 	if err != nil {
 		log.Fatal(err)
 	}
 	defer resp.Body.Close()
 
-	if resp.Status.Class() != gemini.StatusSuccess {
-		log.Fatalf("%d %s", resp.Status, resp.Meta)
-	}
 	if resp.Meta != "text/gemini" && !strings.HasPrefix(resp.Meta, "text/gemini;") {
 		log.Fatal("mime type is not text/gemini")
 	}
@@ -208,6 +398,11 @@ func (a ByTime) Swap(i, j int) {
 	a[i], a[j] = a[j], a[i]
 }
 
+type PError struct {
+	code    gemini.Status
+	message string
+}
+
 type AtomWriter struct {
 	Title string
 	Items []FeedItem