Files
moby/daemon/libnetwork/internal/nftables/nft_cgo_linux.go
2025-09-24 18:27:17 +01:00

79 lines
2.0 KiB
Go

//go:build cgo && !static_build
package nftables
import (
"context"
"errors"
"fmt"
"unsafe"
"github.com/containerd/log"
"go.opentelemetry.io/otel"
)
// #cgo pkg-config: libnftables
// #cgo nocallback nft_run_cmd_from_buffer
// #cgo nocallback nft_ctx_get_output_buffer
// #cgo nocallback nft_ctx_get_error_buffer
// #include <stdlib.h>
// #include <nftables/libnftables.h>
import "C"
type nftHandle = *C.struct_nft_ctx
// nftApply calls libnftables to execute the nftables commands in nftCmd.
// Acquire t.applyLock before calling this function.
func (t *table) nftApply(ctx context.Context, nftCmd []byte) error {
ctx, span := otel.Tracer("").Start(ctx, spanPrefix+".nftApply.cgo")
defer span.End()
if t.nftHandle == nil {
handle, err := newNftHandle()
if err != nil {
return err
}
t.nftHandle = handle
}
cCmd := C.CString(string(nftCmd))
defer C.free(unsafe.Pointer(cCmd))
ret := C.nft_run_cmd_from_buffer(t.nftHandle, cCmd)
stdout := C.GoString(C.nft_ctx_get_output_buffer(t.nftHandle))
stderr := C.GoString(C.nft_ctx_get_error_buffer(t.nftHandle))
if ret != 0 {
return fmt.Errorf("libnftables: failed to apply commands (code %d), stderr: %s", int(ret), stderr)
}
log.G(ctx).WithFields(log.Fields{"stdout": stdout, "stderr": stderr}).Debug("nftables: updated via libnftables")
return nil
}
func newNftHandle() (_ *C.struct_nft_ctx, retErr error) {
handle := C.nft_ctx_new(C.NFT_CTX_DEFAULT)
if handle == nil {
return nil, errors.New("libnftables: failed to create new nft handle")
}
defer func() {
if retErr != nil {
C.nft_ctx_free(handle)
}
}()
if ret := C.nft_ctx_buffer_output(handle); ret != 0 {
return nil, fmt.Errorf("libnftables: failed to set output buffer (code %d)", int(ret))
}
if ret := C.nft_ctx_buffer_error(handle); ret != 0 {
return nil, fmt.Errorf("libnftables: failed to set error buffer (code %d)", int(ret))
}
return handle, nil
}
func (t *table) closeNftHandle() {
t.applyLock.Lock()
defer t.applyLock.Unlock()
if t.nftHandle != nil {
C.nft_ctx_free(t.nftHandle)
t.nftHandle = nil
}
}