icecast: implement the icecast Source connection without net/http

net/http seems to really want to read the whole response if you use
the functions provided to read a response from an arbitrary reader.
But because we don't actually send any body from the proxy it just
hangs instead. This is probably a fault in the proxy but haven't
figured out how to fix that yet.

streamer/icecast/metadata.go

@@ -14,7 +14,7 @@ type MetadataFunc func(ctx context.Context, metadata string) error
 
 // MetadataURL takes an URL as passed to DialURL and creates a function
 // that can be called to send metadata to icecast for that DialURL
-func MetadataURL(u *url.URL, opts ...Option) (MetadataFunc, error) {
+func MetadataURL(u *url.URL, opts ...Option) MetadataFunc {
 	uc, _ := url.Parse(u.String())
 	mount := uc.Path
 
@@ -30,7 +30,7 @@ func MetadataURL(u *url.URL, opts ...Option) (MetadataFunc, error) {
 
 		req, err := http.NewRequestWithContext(ctx, http.MethodGet, uc.String(), nil)
 		if err != nil {
-			return fmt.Errorf("MetadataURL: failed to create request: %w", err)
+			return fmt.Errorf("MetadataFunc: failed to create request: %w", err)
 		}
 		for _, opt := range opts {
 			opt(req)
@@ -39,21 +39,21 @@ func MetadataURL(u *url.URL, opts ...Option) (MetadataFunc, error) {
 
 		resp, err := DefaultClient.Do(req)
 		if err != nil {
-			return fmt.Errorf("MetadataURL: failed Do: %w", err)
+			return fmt.Errorf("MetadataFunc: failed Do: %w", err)
 		}
 
 		if resp.StatusCode != http.StatusOK {
-			return fmt.Errorf("MetadataURL: status not ok: %w", errors.New(resp.Status))
+			return fmt.Errorf("MetadataFunc: status not ok: %w", errors.New(resp.Status))
 		}
 
 		return nil
-	}, nil
+	}
 }
 
 func Metadata(u string, opts ...Option) (MetadataFunc, error) {
 	uri, err := url.Parse(u)
 	if err != nil {
 		return nil, err
 	}
-	return MetadataURL(uri)
+	return MetadataURL(uri), nil
 }

streamer/icecast/source.go

@@ -7,7 +7,9 @@ import (
 	"fmt"
 	"net"
 	"net/http"
+	"net/textproto"
 	"net/url"
+	"strings"
 )
 
 var Dialer net.Dialer
@@ -141,14 +143,25 @@ func dial(ctx context.Context, u *url.URL, opts ...Option) (net.Conn, error) {
 	}
 
 	rdr := bufio.NewReader(conn)
-	resp, err := http.ReadResponse(rdr, req)
+	line, err := textproto.NewReader(rdr).ReadLine()
 	if err != nil {
-		return conn, fmt.Errorf("failed to read request: %w", err)
+		return conn, fmt.Errorf("failed to read response: %w", err)
 	}
-	resp.Body.Close()
 
-	if resp.StatusCode != http.StatusOK {
-		return conn, fmt.Errorf("status not ok: %w", errors.New(resp.Status))
+	_, status, ok := strings.Cut(line, " ")
+	if !ok {
+		return conn, fmt.Errorf("malformed HTTP response: %s", line)
+	}
+
+	status = strings.TrimLeft(status, " ")
+
+	statusCode, _, _ := strings.Cut(status, " ")
+	if len(statusCode) != 3 {
+		return conn, fmt.Errorf("malformed HTTP status code: %s", statusCode)
+	}
+
+	if statusCode != "200" {
+		return conn, fmt.Errorf("status not ok: %w", errors.New(status))
 	}
 
 	return conn, nil