From 9bed6157351eea6fdbccff69aba5cc967a0b2a56 Mon Sep 17 00:00:00 2001
From: Feuerfuchs <git@feuerfuchs.dev>
Date: Sat, 16 Nov 2019 00:55:25 +0100
Subject: Initial Gemini support

---
 libgemini.go | 153 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 153 insertions(+)
 create mode 100644 libgemini.go

(limited to 'libgemini.go')

diff --git a/libgemini.go b/libgemini.go
new file mode 100644
index 0000000..05321ef
--- /dev/null
+++ b/libgemini.go
@@ -0,0 +1,153 @@
+package gopherproxy
+
+import (
+	"bufio"
+	"crypto/tls"
+	"errors"
+	"io"
+	"net/url"
+	"regexp"
+	"strconv"
+	"strings"
+)
+
+const (
+	CRLF = "\r\n"
+)
+
+const (
+	STATUS_INPUT                  = 10
+	STATUS_SUCCESS                = 20
+	STATUS_SUCCESS_CERT           = 21
+	STATUS_REDIRECT_TEMP          = 30
+	STATUS_REDIRECT_PERM          = 31
+	STATUS_TEMP_FAILURE           = 40
+	STATUS_SERVER_UNAVAILABLE     = 41
+	STATUS_CGI_ERROR              = 42
+	STATUS_PROXY_ERROR            = 43
+	STATUS_SLOW_DOWN              = 44
+	STATUS_PERM_FAILURE           = 50
+	STATUS_NOT_FOUND              = 51
+	STATUS_GONE                   = 52
+	STATUS_PROXY_REFUSED          = 53
+	STATUS_BAD_REQUEST            = 59
+	STATUS_CLIENT_CERT_EXPIRED    = 60
+	STATUS_TRANSIENT_CERT_REQUEST = 61
+	STATUS_AUTH_CERT_REQUIRED     = 62
+	STATUS_CERT_REJECTED          = 63
+	STATUS_FUTURE_CERT_REJECTED   = 64
+	STATUS_EXPIRED_CERT_REJECTED  = 65
+)
+
+const (
+	MIME_GEMINI     = "text/gemini"
+	DEFAULT_MIME    = MIME_GEMINI
+	DEFAULT_CHARSET = "utf-8"
+)
+
+var (
+	HeaderPattern      = regexp.MustCompile("^(\\d\\d)[ \\t]+(.*)$")
+	MimeTypePattern    = regexp.MustCompile("^[-\\w.]+/[-\\w.]+")
+	MimeCharsetPattern = regexp.MustCompile("charset=([^ ;]+)")
+	GeminiLinkPattern  = regexp.MustCompile("^=>[ \\t]*([^ ]+)(?:[ \\t]+(.*))?$")
+)
+
+type GeminiHeader struct {
+	Status int
+	Meta   string
+}
+
+type GeminiResponse struct {
+	Header *GeminiHeader
+	Body   io.Reader
+}
+
+func GeminiGet(uri string) (*GeminiResponse, error) {
+	u, err := url.Parse(uri)
+	if err != nil {
+		return nil, err
+	}
+
+	if u.Scheme != "gemini" {
+		return nil, errors.New("invalid scheme for uri")
+	}
+
+	var (
+		host string
+		port int
+	)
+
+	hostport := strings.Split(u.Host, ":")
+	if len(hostport) == 2 {
+		host = hostport[0]
+		n, err := strconv.ParseInt(hostport[1], 10, 32)
+		if err != nil {
+			return nil, err
+		}
+		port = int(n)
+	} else {
+		host, port = hostport[0], 1965
+	}
+
+	conn, err := tls.Dial("tcp", host+":"+strconv.Itoa(port), &tls.Config{
+		MinVersion:         tls.VersionTLS12,
+		InsecureSkipVerify: true,
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	_, err = conn.Write([]byte(u.String() + CRLF))
+	if err != nil {
+		conn.Close()
+		return nil, err
+	}
+
+	reader := bufio.NewReader(conn)
+
+	line, _, err := reader.ReadLine()
+	if err != nil {
+		conn.Close()
+		return nil, err
+	}
+
+	header, err := ParseGeminiHeader(string(line))
+	if err != nil {
+		conn.Close()
+		return nil, err
+	}
+
+	return &GeminiResponse{
+		Header: header,
+		Body:   reader,
+	}, nil
+}
+
+func ParseGeminiHeader(line string) (header *GeminiHeader, err error) {
+	matches := HeaderPattern.FindStringSubmatch(line)
+
+	status, err := strconv.Atoi(matches[1])
+	if err != nil {
+		return nil, err
+	}
+
+	meta := matches[2]
+
+	if int(status/10) == 2 {
+		if meta == "" {
+			meta = DEFAULT_MIME + ";charset=" + DEFAULT_CHARSET
+		}
+
+		mimeType := MimeTypePattern.FindString(meta)
+		if strings.HasPrefix(mimeType, "text/") && MimeCharsetPattern.FindString(meta) == "" {
+			meta += ";charset=" + DEFAULT_CHARSET
+		}
+	}
+
+	header = &GeminiHeader{
+		Status: status,
+		Meta:   meta,
+	}
+
+	return
+}
-- 
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