aplay/mixer: factor out sockaddr_compare

Author: MartinPulec

src/audio/playback/mixer.cpp

@@ -89,40 +89,8 @@ using namespace std::chrono;
 class sockaddr_storage_less {
 public:
         bool operator() (const sockaddr_storage & x, const sockaddr_storage & y) const {
-                if (x.ss_family != y.ss_family) {
-                        return x.ss_family < y.ss_family;
-                }
-
-                if (x.ss_family == AF_INET) {
-                        const auto &sin_x =
-                            reinterpret_cast<const sockaddr_in &>(x);
-                        const auto &sin_y =
-                            reinterpret_cast<const sockaddr_in &>(y);
-
-                        if (sin_x.sin_addr.s_addr != sin_y.sin_addr.s_addr) {
-                                return sin_x.sin_addr.s_addr < sin_y.sin_addr.s_addr;
-                        }
-                        return sin_x.sin_port < sin_y.sin_port;
-                } else if (x.ss_family == AF_INET6) {
-                        const auto &sin_x =
-                            reinterpret_cast<const sockaddr_in6 &>(x);
-                        const auto &sin_y =
-                            reinterpret_cast<const sockaddr_in6 &>(y);
-
-                        for (int i = 0; i < 16; ++i) {
-                                if (sin_x.sin6_addr.s6_addr[i] != sin_y.sin6_addr.s6_addr[i]) {
-                                        return sin_x.sin6_addr.s6_addr[i] < sin_y.sin6_addr.s6_addr[i];
-                                }
-                        }
-
-                        if (IN6_IS_ADDR_LINKLOCAL(&sin_x.sin6_addr) &&
-                            sin_x.sin6_scope_id != sin_y.sin6_scope_id) {
-                                return sin_x.sin6_scope_id < sin_y.sin6_scope_id;
-                        }
-
-                        return sin_x.sin6_port < sin_y.sin6_port;
-                }
-                abort();
+                return sockaddr_compare((const sockaddr *) &x,
+                                        (const sockaddr *) &y) < 0;
         }
 };
 

src/utils/net.c

@@ -518,6 +518,58 @@ get_sockaddr(const char *hostport, int mode)
         return ret;
 }
 
+/**
+ * @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
+ */
+int
+sockaddr_compare(const struct sockaddr *x, const struct sockaddr *y)
+{
+        if (x->sa_family != y->sa_family) {
+                return y->sa_family - x->sa_family;
+        }
+
+        if (x->sa_family == AF_INET) {
+                const struct sockaddr_in *sin_x = (const void *) x;
+                const struct sockaddr_in *sin_y = (const void *) y;
+
+                if (sin_x->sin_addr.s_addr != sin_y->sin_addr.s_addr) {
+                        return ntohl(sin_x->sin_addr.s_addr) <
+                                       ntohl(sin_y->sin_addr.s_addr)
+                                   ? -1
+                                   : 1;
+                }
+                return ntohs(sin_y->sin_port) - ntohs(sin_x->sin_port);
+        }
+        if (x->sa_family == AF_INET6) {
+                const struct sockaddr_in6 *sin_x = (const void *) x;
+                const struct sockaddr_in6 *sin_y = (const void *) y;
+
+                for (int i = 0; i < 16; ++i) {
+                        if (sin_x->sin6_addr.s6_addr[i] !=
+                            sin_y->sin6_addr.s6_addr[i]) {
+                                return sin_y->sin6_addr.s6_addr[i] -
+                                       sin_x->sin6_addr.s6_addr[i];
+                        }
+                }
+
+                // sin6_scope_id is opaque so do not cope with endianity
+                // (actually it is host order on both Linux and Windows)
+                if (IN6_IS_ADDR_LINKLOCAL(&sin_x->sin6_addr) &&
+                    sin_x->sin6_scope_id != sin_y->sin6_scope_id) {
+                        return sin_x->sin6_scope_id < sin_y->sin6_scope_id ? -1
+                                                                           : 1;
+                }
+
+                return ntohs(sin_y->sin6_port) - sin_x->sin6_port;
+        }
+        MSG(ERROR, "Unsupported address class %d!", (int) x->sa_family);
+        abort();
+}
+
 const char *ug_gai_strerror(int errcode)
 {
 #ifdef _WIN32

src/utils/net.h

@@ -91,6 +91,7 @@ char *get_sockaddr_str(const struct sockaddr *sa, unsigned sa_len, char *buf,
                        size_t n);
 struct sockaddr_storage get_sockaddr(const char *hostport, int mode);
 const char *ug_gai_strerror(int errcode);
+int sockaddr_compare(const struct sockaddr *x, const struct sockaddr *y);
 
 #ifdef _WIN32
 #define CLOSESOCKET closesocket