sockaddr_compare: handle v4-mapped sockaddr_in6

Current implementation of resolve_addrinfo defaults to v4-mapped ipv6
addresses even for dotted decimal.

Author: MartinPulec

src/utils/net.c

@@ -518,16 +518,48 @@ get_sockaddr(const char *hostport, int mode)
         return ret;
 }
 
+/**
+ * If addr6 is not a v4-mapped address, return it.
+ * Otherwise convert to sockaddr_in AF_INET address.
+ */
+static const struct sockaddr *
+v4_unmap(const struct sockaddr_in6 *addr6, struct sockaddr_in *buf4)
+{
+        if (!IN6_IS_ADDR_V4MAPPED(&addr6->sin6_addr)) {
+                return (const struct sockaddr *) addr6;
+        }
+        buf4->sin_family = AF_INET;
+        buf4->sin_port = addr6->sin6_port;
+        union {
+                uint8_t bytes[4];
+                uint32_t word;
+        } u;
+        for (int i = 0; i < 4; ++i) {
+                u.bytes[i] = addr6->sin6_addr.s6_addr[12 + i];
+        }
+        buf4->sin_addr.s_addr = u.word;
+        return (struct sockaddr *) buf4;
+}
+
 /**
  * @retval <0 struct represents "smaller" address (port)
  * @retval 0  addresses equal
  * @retval >0 struct represents "bigger" address (port)
  * @note
- * v4-mapped ports are not handled
+ * v4-mapped ipv6 address is considered eqaul to corresponding AF_INET addr
  */
 int
 sockaddr_compare(const struct sockaddr *x, const struct sockaddr *y)
 {
+        struct sockaddr_in tmp1;
+        if (x->sa_family == AF_INET6) {
+                x = v4_unmap((const struct sockaddr_in6 *) x, &tmp1);
+        }
+        struct sockaddr_in tmp2;
+        if (y->sa_family == AF_INET6) {
+                y = v4_unmap((const struct sockaddr_in6 *) y, &tmp2);
+        }
+
         if (x->sa_family != y->sa_family) {
                 return y->sa_family - x->sa_family;
         }
@@ -564,7 +596,7 @@ sockaddr_compare(const struct sockaddr *x, const struct sockaddr *y)
                                                                            : 1;
                 }
 
-                return ntohs(sin_y->sin6_port) - sin_x->sin6_port;
+                return ntohs(sin_y->sin6_port) - ntohs(sin_x->sin6_port);
         }
         MSG(ERROR, "Unsupported address class %d!", (int) x->sa_family);
         abort();

test/misc_test.cpp

@@ -14,9 +14,10 @@
 
 extern "C" {
 int misc_test_color_coeff_range();
+int misc_test_net_getsockaddr();
+int misc_test_net_sockaddr_compare_v4_mapped();
 int misc_test_replace_all();
 int misc_test_video_desc_io_op_symmetry();
-int misc_test_net_getsockaddr();
 }
 
 using namespace std;
@@ -108,6 +109,15 @@ misc_test_net_getsockaddr()
         return 0;
 }
 
+int misc_test_net_sockaddr_compare_v4_mapped() {
+        struct sockaddr_storage v4 = get_sockaddr("10.0.0.1:10", 4);
+        struct sockaddr_storage v4mapped = get_sockaddr("10.0.0.1:10", 0);
+        ASSERT_MESSAGE("V4 mapped address doesn't equal plain V4",
+                       sockaddr_compare((struct sockaddr *) &v4,
+                                        (struct sockaddr *) &v4mapped) == 0);
+        return 0;
+}
+
 #ifdef __clang__
 #pragma clang diagnostic ignored "-Wstring-concatenation"
 #endif

test/run_tests.c

@@ -88,6 +88,7 @@ DECLARE_TEST(gpujpeg_test_simple);
 DECLARE_TEST(libavcodec_test_get_decoder_from_uv_to_uv);
 DECLARE_TEST(misc_test_color_coeff_range);
 DECLARE_TEST(misc_test_net_getsockaddr);
+DECLARE_TEST(misc_test_net_sockaddr_compare_v4_mapped);
 DECLARE_TEST(misc_test_replace_all);
 DECLARE_TEST(misc_test_video_desc_io_op_symmetry);
 
@@ -123,6 +124,7 @@ struct {
         DEFINE_TEST(libavcodec_test_get_decoder_from_uv_to_uv),
         DEFINE_TEST(misc_test_color_coeff_range),
         DEFINE_TEST(misc_test_net_getsockaddr),
+        DEFINE_TEST(misc_test_net_sockaddr_compare_v4_mapped),
         DEFINE_TEST(misc_test_replace_all),
         DEFINE_TEST(misc_test_video_desc_io_op_symmetry),
 };