1 files changed, 32 insertions, 0 deletions
diff --git a/daemon/src/checksum.c b/daemon/src/checksum.c
new file mode 100644
index 0000000..41866ff
--- /dev/null
+++ b/daemon/src/checksum.c
@@ -0,0 +1,32 @@
+/* 
+ * Extracted from RFC 1071 with some minor changes to fix compilation on GCC,
+ * this can probably be improved
+ * 					--pablo 11/feb/07
+ */
+
+#include <conntrackd.h>
+
+unsigned short do_csum(const void *addr, unsigned int count)
+{
+	unsigned int sum = 0;
+
+	/* checksumming disabled, just skip */
+	if (CONFIG(flags) & DONT_CHECKSUM)
+		return 0;
+
+	while(count > 1)  {
+		/*  This is the inner loop */
+		sum += *((unsigned short *) addr++);
+		count -= 2;
+	}
+
+	/*  Add left-over byte, if any */
+	if(count > 0)
+		sum += *((unsigned char *) addr);
+
+	/*  Fold 32-bit sum to 16 bits */
+	while (sum>>16)
+		sum = (sum & 0xffff) + (sum >> 16);
+
+	return ~sum;
+}