Add ipv4 helpers

src/packet/ipv4_helpers.h

@@ -0,0 +1,71 @@
+#ifndef _IPV4_HELPERS_H
+#define _IPV4_HELPERS_H
+
+#ifdef __cpluscplus
+extern "C"
+{
+#endif
+
+#include <arpa/inet.h>
+#include <netinet/ip.h>
+
+static inline uint16_t ipv4_hdr_get_ipid(const struct ip *hdr)
+{
+    return ntohs(hdr->ip_id);
+}
+
+static inline uint8_t ipv4_hdr_get_flags(const struct ip *hdr)
+{
+    return (ntohs(hdr->ip_off) & IP_OFFMASK) >> 13;
+}
+
+static inline uint16_t ipv4_hdr_get_frag_offset(const struct ip *hdr)
+{
+    return ntohs(hdr->ip_off) & IP_OFFMASK;
+}
+
+static inline uint8_t ipv4_hdr_get_ttl(const struct ip *hdr)
+{
+    return hdr->ip_ttl;
+}
+
+static inline uint8_t ipv4_hdr_get_protocol(const struct ip *hdr)
+{
+    return hdr->ip_p;
+}
+
+static inline uint16_t ipv4_hdr_get_checksum(const struct ip *hdr)
+{
+    return ntohs(hdr->ip_sum);
+}
+
+static inline uint32_t ipv4_hdr_get_src(const struct ip *hdr)
+{
+    return ntohl(hdr->ip_src.s_addr);
+}
+
+static inline uint32_t ipv4_hdr_get_dst(const struct ip *hdr)
+{
+    return ntohl(hdr->ip_dst.s_addr);
+}
+
+static inline bool ipv4_hdr_has_flag_rf(const struct ip *hdr)
+{
+    return (ntohs(hdr->ip_off) & IP_RF) != 0;
+}
+
+static inline bool ipv4_hdr_has_flag_df(const struct ip *hdr)
+{
+    return (ntohs(hdr->ip_off) & IP_DF) != 0;
+}
+
+static inline bool ipv4_hdr_has_flag_mf(const struct ip *hdr)
+{
+    return (ntohs(hdr->ip_off) & IP_MF) != 0;
+}
+
+#ifdef __cpluscplus
+}
+#endif
+
+#endif

src/packet/test/CMakeLists.txt

@@ -10,6 +10,11 @@ add_executable(gtest_packet_helpers gtest_packet_helpers.cpp)
 target_include_directories(gtest_packet_helpers PUBLIC ${CMAKE_CURRENT_LIST_DIR})
 target_link_libraries(gtest_packet_helpers packet gtest)
 
+add_executable(gtest_ipv4_helpers gtest_ipv4_helpers.cpp)
+target_include_directories(gtest_ipv4_helpers PUBLIC ${CMAKE_CURRENT_LIST_DIR})
+target_link_libraries(gtest_ipv4_helpers packet gtest)
+
 include(GoogleTest)
 gtest_discover_tests(gtest_packet)
 gtest_discover_tests(gtest_packet_helpers)
+gtest_discover_tests(gtest_ipv4_helpers)

src/packet/test/gtest_ipv4_helpers.cpp

@@ -0,0 +1,51 @@
+#include <gtest/gtest.h>
+
+#include "ipv4_helpers.h"
+
+/*
+ * Internet Protocol Version 4, Src: 192.168.36.103, Dst: 192.168.40.137
+ *     0100 .... = Version: 4
+ *     .... 0101 = Header Length: 20 bytes (5)
+ *     Differentiated Services Field: 0x00 (DSCP: CS0, ECN: Not-ECT)
+ *         0000 00.. = Differentiated Services Codepoint: Default (0)
+ *         .... ..00 = Explicit Congestion Notification: Not ECN-Capable Transport (0)
+ *     Total Length: 44
+ *     Identification: 0xffff (65535)
+ *     001. .... = Flags: 0x1, More fragments
+ *         0... .... = Reserved bit: Not set
+ *         .0.. .... = Don't fragment: Not set
+ *         ..1. .... = More fragments: Set
+ *     ...0 0000 0000 0000 = Fragment Offset: 0
+ *     Time to Live: 127
+ *     Protocol: TCP (6)
+ *     Header Checksum: 0x4d8b [correct]
+ *     [Header checksum status: Good]
+ *     [Calculated Checksum: 0x4d8b]
+ *     Source Address: 192.168.36.103
+ *     Destination Address: 192.168.40.137
+ *     [Reassembled IPv4 in frame: 5]
+ * Data (24 bytes)
+ */
+
+unsigned char hdr[] = {0x45, 0x00, 0x00, 0x2c, 0xff, 0xff, 0x20, 0x00, 0x7f, 0x06, 0x4d, 0x8b, 0xc0, 0xa8, 0x24, 0x67, 0xc0, 0xa8, 0x28, 0x89};
+
+TEST(IPV4_HELPERS, GET)
+{
+    EXPECT_TRUE(ipv4_hdr_get_ipid((struct ip *)hdr) == 65535);
+    EXPECT_TRUE(ipv4_hdr_get_flags((struct ip *)hdr) == 1);
+    EXPECT_TRUE(ipv4_hdr_get_frag_offset((struct ip *)hdr) == 0);
+    EXPECT_TRUE(ipv4_hdr_get_ttl((struct ip *)hdr) == 127);
+    EXPECT_TRUE(ipv4_hdr_get_protocol((struct ip *)hdr) == 6);
+    EXPECT_TRUE(ipv4_hdr_get_checksum((struct ip *)hdr) == 0x4d8b);
+    EXPECT_TRUE(ipv4_hdr_get_src((struct ip *)hdr) == 0xc0a82467);
+    EXPECT_TRUE(ipv4_hdr_get_dst((struct ip *)hdr) == 0xc0a82889);
+    EXPECT_TRUE(ipv4_hdr_has_flag_rf((struct ip *)hdr) == false);
+    EXPECT_TRUE(ipv4_hdr_has_flag_df((struct ip *)hdr) == false);
+    EXPECT_TRUE(ipv4_hdr_has_flag_mf((struct ip *)hdr) == true);
+}
+
+int main(int argc, char **argv)
+{
+    ::testing::InitGoogleTest(&argc, argv);
+    return RUN_ALL_TESTS();
+}