1 files changed, 45 insertions, 0 deletions
diff --git a/src/dnsstub/dns_sortip.c b/src/dnsstub/dns_sortip.c
new file mode 100644
index 0000000..38f5df2
--- /dev/null
+++ b/src/dnsstub/dns_sortip.c
@@ -0,0 +1,45 @@
+#include "byte.h"
+#include "ip.h"
+#include "dnsresolv.h"
+
+/**
+	* @file dns_sortip.c
+	* @authors djb, fefe, feh
+	* @ref ucspi-tcp6
+	* @brief random sort of DNS servers per IP
+  */
+
+/* XXX: sort servers by configurable notion of closeness? */
+/* XXX: pay attention to competence of each server? */
+/* XXX: pay attention to qualification (DNSSec, DNSCurve) of each server? */
+/* YYY: we use a randomly sorted list of NS; not depending on answer */
+
+void dns_sortip4(char *s,unsigned int n)
+{
+  unsigned int i;
+  char tmp[4];
+
+  n >>= 2;	/* 4 byte per IPv4 address */
+  while (n > 1) {
+    i = dns_random(n);
+    --n;
+    byte_copy(tmp,4,s + (i << 2));
+    byte_copy(s + (i << 2),4,s + (n << 2));
+    byte_copy(s + (n << 2),4,tmp);
+  }
+}
+
+void dns_sortip6(char *s,unsigned int n)
+{
+  unsigned int i;
+  char tmp[16];
+
+  n >>= 4;	/* 16 byte per IPv4 address */
+  while (n > 1) {
+    i = dns_random(n);
+    --n;
+    byte_copy(tmp,16,s + (i << 4));
+    byte_copy(s + (i << 4),16,s + (n << 4));
+    byte_copy(s + (n << 4),16,tmp);
+  }
+}