Initial commit

1 files changed, 107 insertions, 0 deletions

diff --git a/client.go b/client.go
new file mode 100644
index 0000000..d529b60
--- /dev/null
+++ b/client.go
@@ -0,0 +1,107 @@
+package gemini
+
+import (
+	"bytes"
+	"crypto/tls"
+	"fmt"
+	"io"
+	"net/url"
+	"strconv"
+	"strings"
+)
+
+// Response represent the response from a Gemini server.
+type Response struct {
+	Status int
+	Meta   string
+	Body   io.ReadCloser
+}
+
+type header struct {
+	status int
+	meta   string
+}
+
+// Fetch a resource from a Gemini server with the given URL
+func Fetch(url string) (res Response, err error) {
+	conn, err := connectByURL(url)
+	if err != nil {
+		return Response{}, fmt.Errorf("failed to connect to the server: %v", err)
+	}
+
+	err = sendRequest(conn, url)
+	if err != nil {
+		conn.Close()
+		return Response{}, err
+	}
+
+	return getResponse(conn)
+}
+
+func connectByURL(rawURL string) (io.ReadWriteCloser, error) {
+	parsedURL, err := url.Parse(rawURL)
+	if err != nil {
+		return nil, fmt.Errorf("failed to parse given URL: %v", err)
+	}
+
+	conf := &tls.Config{
+		InsecureSkipVerify: true,
+	}
+
+	return tls.Dial("tcp", parsedURL.Host, conf)
+}
+
+func sendRequest(conn io.Writer, requestURL string) error {
+	_, err := fmt.Fprintf(conn, "%s\r\n", requestURL)
+	if err != nil {
+		return fmt.Errorf("could not send request to the server: %v", err)
+	}
+
+	return nil
+}
+
+func getResponse(conn io.ReadCloser) (Response, error) {
+	header, err := getHeader(conn)
+	if err != nil {
+		conn.Close()
+		return Response{}, fmt.Errorf("failed to get header: %v", err)
+	}
+
+	return Response{header.status, header.meta, conn}, nil
+}
+
+func getHeader(conn io.Reader) (header, error) {
+	line, err := readHeader(conn)
+	if err != nil {
+		return header{}, fmt.Errorf("failed to read header: %v", err)
+	}
+
+	fields := strings.Fields(string(line))
+	status, err := strconv.Atoi(fields[0])
+	if err != nil {
+		return header{}, fmt.Errorf("unexpected status value %v: %v", fields[0], err)
+	}
+
+	meta := strings.Join(fields[1:], " ")
+
+	return header{status, meta}, nil
+}
+
+func readHeader(conn io.Reader) ([]byte, error) {
+	var line []byte
+	delim := []byte("\r\n")
+	// A small buffer is inefficient but the maximum length of the header is small so it's okay
+	buf := make([]byte, 1)
+
+	for {
+		_, err := conn.Read(buf)
+		if err != nil {
+			return []byte{}, err
+		}
+
+		line = append(line, buf...)
+		if bytes.HasSuffix(line, delim) {
+			return line[:len(line)-len(delim)], nil
+		}
+	}
+}