Code cleanup

src/ip.h

@@ -0,0 +1,39 @@
+#pragma once
+
+#include <stdint.h>
+
+struct ip_common {
+    uint8_t version;
+    uint8_t proto;
+    uint8_t hdr_size;
+    uint16_t size;
+};
+
+_pure_
+static inline uint8_t ip_get_version (const uint8_t *data, size_t size)
+{
+    if (size<20)
+        return 0;
+
+    return data[0]>>4;
+}
+
+static inline int ip_get_common (struct ip_common *ic, const uint8_t *data, size_t size)
+{
+    ic->version = ip_get_version(data, size);
+
+    switch (ic->version) {
+    case 4:
+        ic->proto = data[9];
+        ic->hdr_size = (data[0]&0xF)<<2;
+        ic->size = ((data[2]<<8)|data[3]);
+        return 0;
+    case 6:
+        ic->proto = data[6];
+        ic->hdr_size = 40;
+        ic->size = ((data[4]<<8)|data[5])+40;
+        return 0;
+    }
+
+    return -1;
+}