cli: auto detect libxdp at build time & fixes

Makefile

@@ -33,6 +33,11 @@ else ifeq ($(MODE), release)
 CFLAGS += -O2
 endif
 
+ifeq ($(USE_LIBXDP),)
+ifeq ($(shell pkg-config --exists 'libxdp >= 1' 'libxdp < 2' >/dev/null 2>&1; echo $$?),0)
+USE_LIBXDP := 1
+endif
+endif
 ifeq ($(USE_LIBXDP),1)
 BPF_CFLAGS += -DMIMIC_USE_LIBXDP
 CFLAGS += -DMIMIC_USE_LIBXDP

src/libxdp.c

@@ -4,7 +4,7 @@
 #include <errno.h>
 #include <xdp/libxdp.h>
 
-#include "common/try.h"
+#include "common/log.h"
 #include "libxdp.h"
 
 static void *libxdp_dl = NULL;
@@ -25,7 +25,10 @@ static int dlsym_many_or_warnv(void *dl, va_list ap) {
     symbol = va_arg(ap, typeof(symbol));
 
     tfn = (typeof(tfn))dlsym(dl, symbol);
-    if (!tfn) ret(-ELIBBAD, "can't find symbol '%s': %s", symbol, dlerror());
+    if (!tfn) {
+      log_warn(_("cannot find symbol '%s': %s"), symbol, dlerror());
+      return -ELIBBAD;
+    }
     *fn = tfn;
   }
 
@@ -39,7 +42,10 @@ static int dlopen_many_sym_or_warn_sentinel(void **dlp, const char *filename, ..
   if (*dlp) return 0;
 
   dl = dlopen(filename, RTLD_NOW | RTLD_NODELETE);
-  if (!dl) ret(-EOPNOTSUPP, "%s is not installed: %s", filename, dlerror());
+  if (!dl) {
+    log_warn(_("%s is not installed: %s"), filename, dlerror());
+    return -EOPNOTSUPP;
+  }
 
   log_debug("loaded '%s' via dlopen()", filename);
 

src/run.c

@@ -766,8 +766,12 @@ int subcmd_run(struct run_args* args) {
   libbpf_set_print(libbpf_print_fn);
 #ifdef MIMIC_USE_LIBXDP
   if (args->use_libxdp) {
-    dlopen_libxdp();
-    sym_libxdp_set_print((libxdp_print_fn_t)libbpf_print_fn);
+    if (dlopen_libxdp() < 0) {
+      log_warn(_("fall back to using libbpf for loading XDP programs"));
+      args->use_libxdp = false;
+    } else {
+      sym_libxdp_set_print((libxdp_print_fn_t)libbpf_print_fn);
+    }
   }
 #endif
   retcode = run_bpf(args, lock_fd, args->ifname, ifindex);