From 67571c49c119993ce553bec68c87e59332b5e03c Mon Sep 17 00:00:00 2001
From: Feuerfuchs <git@feuerfuchs.dev>
Date: Sat, 16 Nov 2019 09:59:03 +0100
Subject: Gemini: Add support for charset MIME parameter

---
 go.mod         |  2 ++
 go.sum         |  1 +
 gopherproxy.go | 48 +++++++++++++++++++++++++++++-------------------
 libgemini.go   | 14 ++++++++------
 4 files changed, 40 insertions(+), 25 deletions(-)

diff --git a/go.mod b/go.mod
index b8e8baf..503bb87 100644
--- a/go.mod
+++ b/go.mod
@@ -7,6 +7,8 @@ require (
 	github.com/nfnt/resize v0.0.0-20180221191011-83c6a9932646
 	github.com/prologic/go-gopher v0.0.0-20181230133552-0c68ed5f58b0
 	github.com/temoto/robotstxt v0.0.0-20180810133444-97ee4a9ee6ea
+	golang.org/x/net v0.0.0-20190311183353-d8887717615a
+	golang.org/x/text v0.3.0
 )
 
 go 1.13
diff --git a/go.sum b/go.sum
index 544eee6..7f255e0 100644
--- a/go.sum
+++ b/go.sum
@@ -83,6 +83,7 @@ golang.org/x/sync v0.0.0-20190412183630-56d357773e84/go.mod h1:RxMgew5VJxzue5/jJ
 golang.org/x/sys v0.0.0-20180905080454-ebe1bf3edb33/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a h1:1BGLXjeY4akVXGgbC9HugT3Jv3hCI0z56oJR5vAMgBU=
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/text v0.3.0 h1:g61tztE5qeGQ89tm6NTjjM9VPIm088od1l6aSorWRWg=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/tools v0.0.0-20190329151228-23e29df326fe/go.mod h1:LCzVGOaR6xXOjkQ3onu1FJEFr0SW1gC7cKk1uF8kGRs=
 golang.org/x/tools v0.0.0-20190404132500-923d25813098 h1:MtqjsZmyGRgMmLUgxnmMJ6RYdvd2ib8ipiayHhqSxs4=
diff --git a/gopherproxy.go b/gopherproxy.go
index ab8e906..65c8f89 100644
--- a/gopherproxy.go
+++ b/gopherproxy.go
@@ -10,11 +10,15 @@ import (
 	"io"
 	"io/ioutil"
 	"log"
+	"mime"
 	"net/http"
 	"net/url"
 	"regexp"
 	"strings"
 
+	"golang.org/x/net/html/charset"
+	"golang.org/x/text/transform"
+
 	"github.com/temoto/robotstxt"
 
 	"github.com/prologic/go-gopher"
@@ -133,7 +137,7 @@ func renderGopherDirectory(w http.ResponseWriter, tpl *template.Template, assetL
 	}{title, fmt.Sprintf("%s/%s", hostport, uri), assetList, out, "", false, "gopher"})
 }
 
-func parseGeminiDocument(response *GeminiResponse, uri string, hostport string) (items []Item) {
+func parseGeminiDocument(body *bytes.Buffer, uri string, hostport string) (items []Item) {
 	baseUrl, err := url.Parse(fmt.Sprintf(
 		"gemini://%s/%s",
 		hostport,
@@ -143,8 +147,7 @@ func parseGeminiDocument(response *GeminiResponse, uri string, hostport string)
 		return []Item{}
 	}
 
-	scanner := bufio.NewScanner(response.Body)
-	scanner.Split(bufio.ScanLines)
+	scanner := bufio.NewScanner(body)
 
 	for scanner.Scan() {
 		line := strings.Trim(scanner.Text(), "\r\n")
@@ -380,25 +383,32 @@ func GeminiHandler(tpl *template.Template, robotsdata *robotstxt.RobotsData, ass
 		}
 
 		if strings.HasPrefix(res.Header.Meta, "text/") {
-			// TODO: Handle encoding
-			// https://stackoverflow.com/questions/32518432/how-to-convert-from-an-encoding-to-utf-8-in-go
+			buf := new(bytes.Buffer)
+
+			_, params, err := mime.ParseMediaType(res.Header.Meta)
+			if err != nil {
+				buf.ReadFrom(res.Body)
+			} else {
+				encoding, _ := charset.Lookup(params["charset"])
+				readbuf := new(bytes.Buffer)
+				readbuf.ReadFrom(res.Body)
+
+				writer := transform.NewWriter(buf, encoding.NewDecoder())
+				writer.Write(readbuf.Bytes())
+				writer.Close()
+			}
+
+			var (
+				rawText string
+				items   []Item
+			)
 
 			if strings.HasPrefix(res.Header.Meta, MIME_GEMINI) {
-				items := parseGeminiDocument(res, uri, hostport)
-				tpl.Execute(w, struct {
-					Title    string
-					URI      string
-					Assets   AssetList
-					RawText  string
-					Lines    []Item
-					Error    bool
-					Protocol string
-				}{uri, fmt.Sprintf("%s/%s", hostport, uri), assetList, "", items, false, "gemini"})
-				return
+				items = parseGeminiDocument(buf, uri, hostport)
+			} else {
+				rawText = buf.String()
 			}
 
-			buf := new(bytes.Buffer)
-			buf.ReadFrom(res.Body)
 			tpl.Execute(w, struct {
 				Title    string
 				URI      string
@@ -407,7 +417,7 @@ func GeminiHandler(tpl *template.Template, robotsdata *robotstxt.RobotsData, ass
 				Lines    []Item
 				Error    bool
 				Protocol string
-			}{uri, fmt.Sprintf("%s/%s", hostport, uri), assetList, buf.String(), nil, false, "gemini"})
+			}{uri, fmt.Sprintf("%s/%s", hostport, uri), assetList, rawText, items, false, "gemini"})
 		} else {
 			io.Copy(w, res.Body)
 		}
diff --git a/libgemini.go b/libgemini.go
index 56e1463..20fc137 100644
--- a/libgemini.go
+++ b/libgemini.go
@@ -5,6 +5,7 @@ import (
 	"crypto/tls"
 	"errors"
 	"io"
+	"mime"
 	"net/url"
 	"regexp"
 	"strconv"
@@ -134,13 +135,14 @@ func ParseGeminiHeader(line string) (header *GeminiHeader, err error) {
 	meta := matches[2]
 
 	if int(status/10) == 2 {
-		if meta == "" {
-			meta = DEFAULT_MIME + ";charset=" + DEFAULT_CHARSET
-		}
+		mediaType, params, err := mime.ParseMediaType(meta)
 
-		mimeType := MimeTypePattern.FindString(meta)
-		if strings.HasPrefix(mimeType, "text/") && MimeCharsetPattern.FindString(meta) == "" {
-			meta += ";charset=" + DEFAULT_CHARSET
+		if err != nil {
+			meta = DEFAULT_MIME + ";charset=" + DEFAULT_CHARSET
+		} else if strings.HasPrefix(mediaType, "text/") {
+			if _, ok := params["charset"]; !ok {
+				meta += ";charset=" + DEFAULT_CHARSET
+			}
 		}
 	}
 
-- 
cgit v1.2.3-70-g09d2