Add ip_get_proto()

src/ip-static.h

@@ -2,6 +2,7 @@
 
 #include <stdint.h>
 
+_pure_
 static inline int ip_get_version (const uint8_t *data, size_t size)
 {
     if (size<20)   // XXX
@@ -10,6 +11,7 @@ static inline int ip_get_version (const uint8_t *data, size_t size)
     return data[0]>>4;
 }
 
+_pure_
 static inline ssize_t ip_get_size (const uint8_t *data, size_t size)
 {
     switch (ip_get_version(data, size)) {
@@ -23,3 +25,18 @@ static inline ssize_t ip_get_size (const uint8_t *data, size_t size)
 
     return 0;
 }
+
+_pure_
+static inline ssize_t ip_get_proto (const uint8_t *data, size_t size)
+{
+    switch (ip_get_version(data, size)) {
+    case 4:
+        return data[9];
+    case 6:
+        return data[6];
+    case -1:
+        return -1;
+    }
+
+    return 0;
+}