reliability: treat zero http.Client timeouts as unbounded

internal/codeguard/checks/reliability/reliability_go_helpers.go

@@ -3,6 +3,8 @@ package reliability
 import (
 	"fmt"
 	"go/ast"
+	"go/token"
+	"math/big"
 	"strings"
 )
 
@@ -195,7 +197,7 @@ func isHTTPClientWithTimeout(expr ast.Expr, aliases map[string]struct{}) bool {
 				continue
 			}
 			if key, ok := kv.Key.(*ast.Ident); ok && key.Name == "Timeout" {
-				return true
+				return !isZeroDuration(kv.Value)
 			}
 		}
 	case *ast.CallExpr:
@@ -204,6 +206,32 @@ func isHTTPClientWithTimeout(expr ast.Expr, aliases map[string]struct{}) bool {
 	return false
 }
 
+func isZeroDuration(expr ast.Expr) bool {
+	switch n := expr.(type) {
+	case *ast.ParenExpr:
+		return isZeroDuration(n.X)
+	case *ast.UnaryExpr:
+		return (n.Op == token.ADD || n.Op == token.SUB) && isZeroDuration(n.X)
+	case *ast.BasicLit:
+		if n.Kind != token.INT {
+			return false
+		}
+		value, ok := new(big.Int).SetString(strings.ReplaceAll(n.Value, "_", ""), 0)
+		return ok && value.Sign() == 0
+	case *ast.CallExpr:
+		// Duration conversions, such as time.Duration(0), preserve zero.
+		return len(n.Args) == 1 && isZeroDuration(n.Args[0])
+	case *ast.BinaryExpr:
+		if n.Op == token.MUL {
+			return isZeroDuration(n.X) || isZeroDuration(n.Y)
+		}
+		if n.Op == token.ADD || n.Op == token.SUB {
+			return isZeroDuration(n.X) && isZeroDuration(n.Y)
+		}
+	}
+	return false
+}
+
 func isHTTPClientType(expr ast.Expr, aliases map[string]struct{}) bool {
 	selector, ok := expr.(*ast.SelectorExpr)
 	if !ok || selector.Sel.Name != "Client" {

tests/checks/reliability_test.go

@@ -162,3 +162,31 @@ func Fetch(ctx context.Context, url string) error {
 	assertFindingRuleAbsent(t, report, "Reliability", "reliability.missing-timeout")
 	assertFindingRuleAbsent(t, report, "Reliability", "reliability.resource-leak")
 }
+
+func TestReliabilityGoFlagsZeroClientTimeout(t *testing.T) {
+	for _, timeout := range []string{"0", "time.Duration(0)", "0 * time.Second"} {
+		t.Run(timeout, func(t *testing.T) {
+			dir := t.TempDir()
+			writeFile(t, filepath.Join(dir, "client.go"), `package sample
+
+import (
+	"net/http"
+	"time"
+)
+
+func Fetch(req *http.Request) error {
+	client := &http.Client{Timeout: `+timeout+`}
+	_, err := client.Do(req)
+	return err
+}
+`)
+
+			report, err := codeguard.Run(context.Background(), reliabilityConfig("reliability-zero-timeout", dir))
+			if err != nil {
+				t.Fatalf("run: %v", err)
+			}
+
+			assertFindingRulePresent(t, report, "Reliability", "reliability.missing-timeout")
+		})
+	}
+}