return a custom error when body size limit is exceeded (#5675)

internal/api/api_config_global.go

@@ -1,7 +1,6 @@
 package api //nolint:revive
 
 import (
-	"io"
 	"net/http"
 
 	"github.com/bluenviron/mediamtx/internal/conf"
@@ -19,7 +18,7 @@ func (a *API) onConfigGlobalGet(ctx *gin.Context) {
 
 func (a *API) onConfigGlobalPatch(ctx *gin.Context) {
 	var c conf.OptionalGlobal
-	err := jsonwrapper.Decode(io.LimitReader(ctx.Request.Body, maxInboundConfigSize), &c)
+	err := jsonwrapper.Decode(&customLimitReader{ctx.Request.Body, maxInboundConfigSize}, &c)
 	if err != nil {
 		a.writeError(ctx, http.StatusBadRequest, err)
 		return

internal/api/api_config_pathdefaults.go

@@ -1,7 +1,6 @@
 package api //nolint:revive
 
 import (
-	"io"
 	"net/http"
 
 	"github.com/bluenviron/mediamtx/internal/conf"
@@ -19,7 +18,7 @@ func (a *API) onConfigPathDefaultsGet(ctx *gin.Context) {
 
 func (a *API) onConfigPathDefaultsPatch(ctx *gin.Context) {
 	var p conf.OptionalPath
-	err := jsonwrapper.Decode(io.LimitReader(ctx.Request.Body, maxInboundConfigSize), &p)
+	err := jsonwrapper.Decode(&customLimitReader{ctx.Request.Body, maxInboundConfigSize}, &p)
 	if err != nil {
 		a.writeError(ctx, http.StatusBadRequest, err)
 		return

internal/api/api_config_paths.go

@@ -3,7 +3,6 @@ package api //nolint:revive
 import (
 	"errors"
 	"fmt"
-	"io"
 	"net/http"
 
 	"github.com/bluenviron/mediamtx/internal/conf"
@@ -64,7 +63,7 @@ func (a *API) onConfigPathsAdd(ctx *gin.Context) { //nolint:dupl
 	}
 
 	var p conf.OptionalPath
-	err := jsonwrapper.Decode(io.LimitReader(ctx.Request.Body, maxInboundConfigSize), &p)
+	err := jsonwrapper.Decode(&customLimitReader{ctx.Request.Body, maxInboundConfigSize}, &p)
 	if err != nil {
 		a.writeError(ctx, http.StatusBadRequest, err)
 		return
@@ -101,7 +100,7 @@ func (a *API) onConfigPathsPatch(ctx *gin.Context) { //nolint:dupl
 	}
 
 	var p conf.OptionalPath
-	err := jsonwrapper.Decode(io.LimitReader(ctx.Request.Body, maxInboundConfigSize), &p)
+	err := jsonwrapper.Decode(&customLimitReader{ctx.Request.Body, maxInboundConfigSize}, &p)
 	if err != nil {
 		a.writeError(ctx, http.StatusBadRequest, err)
 		return
@@ -142,7 +141,7 @@ func (a *API) onConfigPathsReplace(ctx *gin.Context) { //nolint:dupl
 	}
 
 	var p conf.OptionalPath
-	err := jsonwrapper.Decode(io.LimitReader(ctx.Request.Body, maxInboundConfigSize), &p)
+	err := jsonwrapper.Decode(&customLimitReader{ctx.Request.Body, maxInboundConfigSize}, &p)
 	if err != nil {
 		a.writeError(ctx, http.StatusBadRequest, err)
 		return

internal/api/custom_limit_reader.go

@@ -0,0 +1,26 @@
+package api
+
+import (
+	"fmt"
+	"io"
+)
+
+var errSizeExceeded = fmt.Errorf("size exceeds maximum allowed")
+
+// like io.LimitReader, but returns a dedicated error if the limit is exceeded.
+type customLimitReader struct {
+	r io.Reader
+	n int64
+}
+
+func (l *customLimitReader) Read(p []byte) (n int, err error) {
+	if l.n <= 0 {
+		return 0, errSizeExceeded
+	}
+	if int64(len(p)) > l.n {
+		p = p[0:l.n]
+	}
+	n, err = l.r.Read(p)
+	l.n -= int64(n)
+	return
+}

internal/auth/custom_limit_reader.go

@@ -0,0 +1,26 @@
+package auth
+
+import (
+	"fmt"
+	"io"
+)
+
+var errSizeExceeded = fmt.Errorf("size exceeds maximum allowed")
+
+// like io.LimitReader, but returns a dedicated error if the limit is exceeded.
+type customLimitReader struct {
+	r io.Reader
+	n int64
+}
+
+func (l *customLimitReader) Read(p []byte) (n int, err error) {
+	if l.n <= 0 {
+		return 0, errSizeExceeded
+	}
+	if int64(len(p)) > l.n {
+		p = p[0:l.n]
+	}
+	n, err = l.r.Read(p)
+	l.n -= int64(n)
+	return
+}

internal/auth/manager.go

@@ -235,7 +235,7 @@ func (m *Manager) authenticateHTTP(req *Request, token string) (string, error) {
 	defer res.Body.Close()
 
 	if res.StatusCode < 200 || res.StatusCode > 299 {
-		resBody, err2 := io.ReadAll(io.LimitReader(res.Body, maxInboundBodySize))
+		resBody, err2 := io.ReadAll(&customLimitReader{res.Body, maxInboundBodySize})
 		if err2 == nil && len(resBody) != 0 {
 			return "", fmt.Errorf("server replied with code %d: %s", res.StatusCode, string(resBody))
 		}
@@ -306,7 +306,7 @@ func (m *Manager) pullJWTJWKS() (jwt.Keyfunc, error) {
 		defer res.Body.Close()
 
 		var raw json.RawMessage
-		err = json.NewDecoder(io.LimitReader(res.Body, maxInboundBodySize)).Decode(&raw)
+		err = json.NewDecoder(&customLimitReader{res.Body, maxInboundBodySize}).Decode(&raw)
 		if err != nil {
 			return nil, err
 		}

internal/protocols/whip/client.go

@@ -264,7 +264,7 @@ func (c *Client) postOffer(
 		return nil, fmt.Errorf("ETag is missing")
 	}
 
-	sdp, err := io.ReadAll(io.LimitReader(res.Body, maxInboundSDPSize))
+	sdp, err := io.ReadAll(&customLimitReader{res.Body, maxInboundSDPSize})
 	if err != nil {
 		return nil, err
 	}

internal/protocols/whip/custom_limit_reader.go

@@ -0,0 +1,26 @@
+package whip
+
+import (
+	"fmt"
+	"io"
+)
+
+var errSizeExceeded = fmt.Errorf("size exceeds maximum allowed")
+
+// like io.LimitReader, but returns a dedicated error if the limit is exceeded.
+type customLimitReader struct {
+	r io.Reader
+	n int64
+}
+
+func (l *customLimitReader) Read(p []byte) (n int, err error) {
+	if l.n <= 0 {
+		return 0, errSizeExceeded
+	}
+	if int64(len(p)) > l.n {
+		p = p[0:l.n]
+	}
+	n, err = l.r.Read(p)
+	l.n -= int64(n)
+	return
+}

internal/servers/hls/hlsjsdownloader/custom_limit_reader.go

@@ -0,0 +1,26 @@
+package main
+
+import (
+	"fmt"
+	"io"
+)
+
+var errSizeExceeded = fmt.Errorf("size exceeds maximum allowed")
+
+// like io.LimitReader, but returns a dedicated error if the limit is exceeded.
+type customLimitReader struct {
+	r io.Reader
+	n int64
+}
+
+func (l *customLimitReader) Read(p []byte) (n int, err error) {
+	if l.n <= 0 {
+		return 0, errSizeExceeded
+	}
+	if int64(len(p)) > l.n {
+		p = p[0:l.n]
+	}
+	n, err = l.r.Read(p)
+	l.n -= int64(n)
+	return
+}

internal/servers/hls/hlsjsdownloader/main.go

@@ -38,7 +38,7 @@ func do() error {
 		return fmt.Errorf("bad status code: %v", res.StatusCode)
 	}
 
-	zipBuf, err := io.ReadAll(io.LimitReader(res.Body, maxInboundHLSJSSize))
+	zipBuf, err := io.ReadAll(&customLimitReader{res.Body, maxInboundHLSJSSize})
 	if err != nil {
 		return err
 	}

internal/servers/webrtc/custom_limit_reader.go

@@ -0,0 +1,26 @@
+package webrtc
+
+import (
+	"fmt"
+	"io"
+)
+
+var errSizeExceeded = fmt.Errorf("size exceeds maximum allowed")
+
+// like io.LimitReader, but returns a dedicated error if the limit is exceeded.
+type customLimitReader struct {
+	r io.Reader
+	n int64
+}
+
+func (l *customLimitReader) Read(p []byte) (n int, err error) {
+	if l.n <= 0 {
+		return 0, errSizeExceeded
+	}
+	if int64(len(p)) > l.n {
+		p = p[0:l.n]
+	}
+	n, err = l.r.Read(p)
+	l.n -= int64(n)
+	return
+}

internal/servers/webrtc/http_server.go

@@ -194,7 +194,7 @@ func (s *httpServer) onWHIPPost(ctx *gin.Context, pathName string, publish bool)
 		return
 	}
 
-	offer, err := io.ReadAll(io.LimitReader(ctx.Request.Body, maxInboundSDPSize))
+	offer, err := io.ReadAll(&customLimitReader{ctx.Request.Body, maxInboundSDPSize})
 	if err != nil {
 		return
 	}
@@ -260,7 +260,7 @@ func (s *httpServer) onWHIPPatch(ctx *gin.Context, pathName string, rawSecret st
 		return
 	}
 
-	byts, err := io.ReadAll(io.LimitReader(ctx.Request.Body, maxInboundSDPSize))
+	byts, err := io.ReadAll(&customLimitReader{ctx.Request.Body, maxInboundSDPSize})
 	if err != nil {
 		return
 	}

internal/staticsources/rpicamera/mtxrpicamdownloader/custom_limit_reader.go

@@ -0,0 +1,26 @@
+package main
+
+import (
+	"fmt"
+	"io"
+)
+
+var errSizeExceeded = fmt.Errorf("size exceeds maximum allowed")
+
+// like io.LimitReader, but returns a dedicated error if the limit is exceeded.
+type customLimitReader struct {
+	r io.Reader
+	n int64
+}
+
+func (l *customLimitReader) Read(p []byte) (n int, err error) {
+	if l.n <= 0 {
+		return 0, errSizeExceeded
+	}
+	if int64(len(p)) > l.n {
+		p = p[0:l.n]
+	}
+	n, err = l.r.Read(p)
+	l.n -= int64(n)
+	return
+}

internal/staticsources/rpicamera/mtxrpicamdownloader/main.go

@@ -79,7 +79,7 @@ func doSingle(version string, f string) error {
 		return fmt.Errorf("bad status code: %v", res.StatusCode)
 	}
 
-	buf, err := io.ReadAll(io.LimitReader(res.Body, maxInboundRPICameraSize))
+	buf, err := io.ReadAll(&customLimitReader{res.Body, maxInboundRPICameraSize})
 	if err != nil {
 		return err
 	}