ci(sec): improve type safety and server organization in HTTP middleware (#4437)

- Update linting configuration to exclude G115 gosec check instead of including specific checks
- Add the safeInt8 helper for safer type conversions and use it to prevent int8 overflow in middleware handler execution
- Group related constants and variables together for better organization in gin.go
- Refactor HTTP server instantiation to use a dedicated http.Server object for all Run methods
- Add the safeUint16 helper and use it to safely handle conversions in tree node functions to prevent uint16 overflow

Signed-off-by: appleboy <appleboy.tw@gmail.com>

.golangci.yml

@@ -18,15 +18,8 @@ linters:
     - wastedassign
   settings:
     gosec:
-      includes:
-        - G102
-        - G106
-        - G108
-        - G109
-        - G111
-        - G112
-        - G201
-        - G203
+      excludes:
+        - G115
     perfsprint:
       int-conversion: true
       err-error: true

context.go

@@ -55,6 +55,14 @@ const ContextRequestKey ContextKeyType = 0
 // abortIndex represents a typical value used in abort functions.
 const abortIndex int8 = math.MaxInt8 >> 1
 
+// safeInt8 converts int to int8 safely, capping at math.MaxInt8
+func safeInt8(n int) int8 {
+	if n > math.MaxInt8 {
+		return math.MaxInt8
+	}
+	return int8(n)
+}
+
 // Context is the most important part of gin. It allows us to pass variables between middleware,
 // manage the flow, validate the JSON of a request and render a JSON response for example.
 type Context struct {
@@ -186,7 +194,7 @@ func (c *Context) FullPath() string {
 // See example in GitHub.
 func (c *Context) Next() {
 	c.index++
-	for c.index < int8(len(c.handlers)) {
+	for c.index < safeInt8(len(c.handlers)) {
 		if c.handlers[c.index] != nil {
 			c.handlers[c.index](c)
 		}

gin.go

@@ -23,10 +23,12 @@ import (
 	"golang.org/x/net/http2/h2c"
 )
 
-const defaultMultipartMemory = 32 << 20 // 32 MB
-const escapedColon = "\\:"
-const colon = ":"
-const backslash = "\\"
+const (
+	defaultMultipartMemory = 32 << 20 // 32 MB
+	escapedColon           = "\\:"
+	colon                  = ":"
+	backslash              = "\\"
+)
 
 var (
 	default404Body = []byte("404 page not found")
@@ -46,8 +48,10 @@ var defaultTrustedCIDRs = []*net.IPNet{
 	},
 }
 
-var regSafePrefix = regexp.MustCompile("[^a-zA-Z0-9/-]+")
-var regRemoveRepeatedChar = regexp.MustCompile("/{2,}")
+var (
+	regSafePrefix         = regexp.MustCompile("[^a-zA-Z0-9/-]+")
+	regRemoveRepeatedChar = regexp.MustCompile("/{2,}")
+)
 
 // HandlerFunc defines the handler used by gin middleware as return value.
 type HandlerFunc func(*Context)
@@ -537,7 +541,11 @@ func (engine *Engine) Run(addr ...string) (err error) {
 	engine.updateRouteTrees()
 	address := resolveAddress(addr)
 	debugPrint("Listening and serving HTTP on %s\n", address)
-	err = http.ListenAndServe(address, engine.Handler())
+	server := &http.Server{ // #nosec G112
+		Addr:    address,
+		Handler: engine.Handler(),
+	}
+	err = server.ListenAndServe()
 	return
 }
 
@@ -553,7 +561,11 @@ func (engine *Engine) RunTLS(addr, certFile, keyFile string) (err error) {
 			"Please check https://github.com/gin-gonic/gin/blob/master/docs/doc.md#dont-trust-all-proxies for details.")
 	}
 
-	err = http.ListenAndServeTLS(addr, certFile, keyFile, engine.Handler())
+	server := &http.Server{ // #nosec G112
+		Addr:    addr,
+		Handler: engine.Handler(),
+	}
+	err = server.ListenAndServeTLS(certFile, keyFile)
 	return
 }
 
@@ -576,7 +588,10 @@ func (engine *Engine) RunUnix(file string) (err error) {
 	defer listener.Close()
 	defer os.Remove(file)
 
-	err = http.Serve(listener, engine.Handler())
+	server := &http.Server{ // #nosec G112
+		Handler: engine.Handler(),
+	}
+	err = server.Serve(listener)
 	return
 }
 
@@ -630,7 +645,10 @@ func (engine *Engine) RunListener(listener net.Listener) (err error) {
 			"Please check https://github.com/gin-gonic/gin/blob/master/docs/doc.md#dont-trust-all-proxies for details.")
 	}
 
-	err = http.Serve(listener, engine.Handler())
+	server := &http.Server{ // #nosec G112
+		Handler: engine.Handler(),
+	}
+	err = server.Serve(listener)
 	return
 }
 

tree.go

@@ -5,6 +5,7 @@
 package gin
 
 import (
+	"math"
 	"net/url"
 	"strings"
 	"unicode"
@@ -77,14 +78,22 @@ func (n *node) addChild(child *node) {
 	}
 }
 
+// safeUint16 converts int to uint16 safely, capping at math.MaxUint16
+func safeUint16(n int) uint16 {
+	if n > math.MaxUint16 {
+		return math.MaxUint16
+	}
+	return uint16(n)
+}
+
 func countParams(path string) uint16 {
 	colons := strings.Count(path, ":")
 	stars := strings.Count(path, "*")
-	return uint16(colons + stars)
+	return safeUint16(colons + stars)
 }
 
 func countSections(path string) uint16 {
-	return uint16(strings.Count(path, "/"))
+	return safeUint16(strings.Count(path, "/"))
 }
 
 type nodeType uint8