bearer: add a package to add/extract a HTTP Authorisation bearer header

toolkit/server/bearer/bearer.go

@@ -0,0 +1,64 @@
+package bearer
+
+import (
+	"fmt"
+	"net/http"
+	"strings"
+
+	"github.com/ucan-wg/go-ucan/pkg/container"
+)
+
+var ErrNoUcan = fmt.Errorf("no ucan")
+var ErrContainerMalformed = fmt.Errorf("malformed container")
+
+// ExtractBearerContainer extract a full UCAN container from an HTTP "Authorization: Bearer" header.
+// It can return:
+// - ErrNoUcan if no such HTTP header is found
+// - ErrContainerMalformed if the container or token can't be decoded or if a token is invalid (bad signature ...)
+func ExtractBearerContainer(h http.Header) (container.Reader, error) {
+	header := h.Get("Authorization")
+	if header == "" {
+		return nil, ErrNoUcan
+	}
+
+	if !strings.HasPrefix(header, "Bearer ") {
+		return nil, ErrNoUcan
+	}
+
+	// skip prefix
+	reader := strings.NewReader(header[len("Bearer "):])
+
+	// read container from any supported format
+	ctn, err := container.FromReader(reader)
+	if err != nil {
+		return nil, fmt.Errorf("%w: %v", ErrContainerMalformed, err)
+	}
+
+	return ctn, nil
+}
+
+// AddBearerContainer adds the given UCAN container into an `Authorization: Bearer` HTTP header.
+//
+// You should use this with HTTP/2 or HTTP/3, as both of those already compress their header.
+func AddBearerContainer(h http.Header, container container.Writer) error {
+	str, err := container.ToBase64StdPadding()
+	if err != nil {
+		return err
+	}
+
+	h.Set("Authorization", fmt.Sprintf("Bearer %s", str))
+	return nil
+}
+
+// AddBearerContainerCompressed adds the given UCAN container into an `Authorization: Bearer` HTTP header.
+//
+// You should use this with HTTP/1, as it doesn't compress its headers.
+func AddBearerContainerCompressed(h http.Header, container container.Writer) error {
+	str, err := container.ToBase64StdPaddingGzipped()
+	if err != nil {
+		return err
+	}
+
+	h.Set("Authorization", fmt.Sprintf("Bearer %s", str))
+	return nil
+}