fix(attrs): use base-10 only for int parsing - prevent hex/octal coercion (#24)

strconv.ParseInt with base 0 auto-detects hex (0x), octal (0o), and
binary (0b) prefixes, causing attribute values like "0x0" and "0xFF"
to silently parse as integers instead of remaining strings. Users
passing hex strings as attribute values got unexpected type coercion.

Fixes #373

🤖 Claude <claude@anthropic.com>

Author: tobert

otlpclient/protobuf_span.go

@@ -164,8 +164,9 @@ func StringMapAttrsToProtobuf(attributes map[string]string) []*commonpb.KeyValue
 	for k, v := range attributes {
 		av := new(commonpb.AnyValue)
 
-		// try to parse as numbers, and fall through to string
-		if i, err := strconv.ParseInt(v, 0, 64); err == nil {
+		// try to parse as decimal numbers, and fall through to string
+		// base 10 only: base 0 would auto-detect hex/octal prefixes (#373)
+		if i, err := strconv.ParseInt(v, 10, 64); err == nil {
 			av.Value = &commonpb.AnyValue_IntValue{IntValue: i}
 		} else if f, err := strconv.ParseFloat(v, 64); err == nil {
 			av.Value = &commonpb.AnyValue_DoubleValue{DoubleValue: f}

otlpclient/protobuf_span_test.go

@@ -192,6 +192,9 @@ func TestCliAttrsToOtel(t *testing.T) {
 		"test 5 - bool, false": "false",
 		"test 6 - bool, True":  "True",
 		"test 7 - bool, False": "False",
+		"test 8 - hex string":  "0x0",
+		"test 9 - hex string2": "0xFF",
+		"test 10 - octal str":  "0o777",
 	}
 
 	otelAttrs := StringMapAttrsToProtobuf(testAttrs)
@@ -228,6 +231,21 @@ func TestCliAttrsToOtel(t *testing.T) {
 			if attr.Value.GetBoolValue() != false {
 				t.Errorf("expected value '%s' for key '%s' but got %t", testAttrs[key], key, attr.Value.GetBoolValue())
 			}
+		case "test 8 - hex string":
+			// #373: 0x0 should be treated as a string, not parsed as hex int
+			if attr.Value.GetStringValue() != "0x0" {
+				t.Errorf("expected string value '0x0' for key '%s' but got parsed as different type", key)
+			}
+		case "test 9 - hex string2":
+			// #373: 0xFF should be treated as a string, not parsed as hex int
+			if attr.Value.GetStringValue() != "0xFF" {
+				t.Errorf("expected string value '0xFF' for key '%s' but got parsed as different type", key)
+			}
+		case "test 10 - octal str":
+			// 0o777 should be treated as a string, not parsed as octal int
+			if attr.Value.GetStringValue() != "0o777" {
+				t.Errorf("expected string value '0o777' for key '%s' but got parsed as different type", key)
+			}
 		}
 	}
 }