Use the new libc_random_u32() in ncmlib to replace random_xid().

ncmlib/random.c

@@ -0,0 +1,38 @@
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+#include <time.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include "log.h"
+#include "io.h"
+
+// Generate a 32-bit pseudorandom number using libc rand()
+uint32_t libc_random_u32(void)
+{
+    static int initialized;
+    if (initialized)
+        return rand();
+
+    uint32_t seed;
+    int fd = open("/dev/urandom", O_RDONLY);
+    if (fd != -1) {
+        int r = safe_read(fd, (char *)&seed, sizeof seed);
+        if (r == -1) {
+            log_warning("Could not read /dev/urandom: %s", strerror(errno));
+            close(fd);
+            seed = time(0);
+        }
+    } else {
+        log_warning("Could not open /dev/urandom: %s", strerror(errno));
+        seed = time(0);
+    }
+    srand(seed);
+    initialized = 1;
+    return rand();
+}
+
+