errors: add errors coder (#946)

* add errors coder

* rename internal http to httputil

* add errors proto

internal/httputil/http.go

@@ -0,0 +1,109 @@
+package httputil
+
+import (
+	"net/http"
+	"strings"
+
+	"google.golang.org/grpc/codes"
+)
+
+const (
+	baseContentType = "application"
+)
+
+// ContentType returns the content-type with base prefix.
+func ContentType(subtype string) string {
+	return strings.Join([]string{baseContentType, subtype}, "/")
+}
+
+// ContentSubtype returns the content-subtype for the given content-type.  The
+// given content-type must be a valid content-type that starts with
+// but no content-subtype will be returned.
+// according rfc7231.
+// contentType is assumed to be lowercase already.
+func ContentSubtype(contentType string) string {
+	left := strings.Index(contentType, "/")
+	if left == -1 {
+		return ""
+	}
+	right := strings.Index(contentType, ";")
+	if right == -1 {
+		right = len(contentType)
+	}
+	if right < left {
+		return ""
+	}
+	return contentType[left+1 : right]
+}
+
+// GRPCCodeFromStatus converts a HTTP error code into the corresponding gRPC response status.
+// See: https://github.com/googleapis/googleapis/blob/master/google/rpc/code.proto
+func GRPCCodeFromStatus(code int) codes.Code {
+	switch code {
+	case http.StatusOK:
+		return codes.OK
+	case http.StatusBadRequest:
+		return codes.InvalidArgument
+	case http.StatusUnauthorized:
+		return codes.Unauthenticated
+	case http.StatusForbidden:
+		return codes.PermissionDenied
+	case http.StatusNotFound:
+		return codes.NotFound
+	case http.StatusConflict:
+		return codes.Aborted
+	case http.StatusTooManyRequests:
+		return codes.ResourceExhausted
+	case http.StatusInternalServerError:
+		return codes.Internal
+	case http.StatusNotImplemented:
+		return codes.Unimplemented
+	case http.StatusServiceUnavailable:
+		return codes.Unavailable
+	case http.StatusGatewayTimeout:
+		return codes.DeadlineExceeded
+	}
+	return codes.Unknown
+}
+
+// StatusFromGRPCCode converts a gRPC error code into the corresponding HTTP response status.
+// See: https://github.com/googleapis/googleapis/blob/master/google/rpc/code.proto
+func StatusFromGRPCCode(code codes.Code) int {
+	switch code {
+	case codes.OK:
+		return http.StatusOK
+	case codes.Canceled:
+		return http.StatusRequestTimeout
+	case codes.Unknown:
+		return http.StatusInternalServerError
+	case codes.InvalidArgument:
+		return http.StatusBadRequest
+	case codes.DeadlineExceeded:
+		return http.StatusGatewayTimeout
+	case codes.NotFound:
+		return http.StatusNotFound
+	case codes.AlreadyExists:
+		return http.StatusConflict
+	case codes.PermissionDenied:
+		return http.StatusForbidden
+	case codes.Unauthenticated:
+		return http.StatusUnauthorized
+	case codes.ResourceExhausted:
+		return http.StatusTooManyRequests
+	case codes.FailedPrecondition:
+		return http.StatusBadRequest
+	case codes.Aborted:
+		return http.StatusConflict
+	case codes.OutOfRange:
+		return http.StatusBadRequest
+	case codes.Unimplemented:
+		return http.StatusNotImplemented
+	case codes.Internal:
+		return http.StatusInternalServerError
+	case codes.Unavailable:
+		return http.StatusServiceUnavailable
+	case codes.DataLoss:
+		return http.StatusInternalServerError
+	}
+	return http.StatusInternalServerError
+}

internal/httputil/http_test.go

@@ -0,0 +1,27 @@
+package httputil
+
+import "testing"
+
+func TestContentSubtype(t *testing.T) {
+	tests := []struct {
+		contentType string
+		want        string
+	}{
+		{"text/html; charset=utf-8", "html"},
+		{"multipart/form-data; boundary=something", "form-data"},
+		{"application/json; charset=utf-8", "json"},
+		{"application/json", "json"},
+		{"application/xml", "xml"},
+		{"text/xml", "xml"},
+		{";text/xml", ""},
+		{"application", ""},
+	}
+	for _, test := range tests {
+		t.Run(test.contentType, func(t *testing.T) {
+			got := ContentSubtype(test.contentType)
+			if got != test.want {
+				t.Fatalf("want %v got %v", test.want, got)
+			}
+		})
+	}
+}