socket-util: introduce port argument in sockaddr_port()

sockaddr_port() either returns a >= 0 port number or a negative errno.
This works for AF_INET and AF_INET6 because port ranges are only 16-bit.

In AF_VSOCK ports are 32-bit so an int cannot represent all port number
and negative errnos.  Separate the port and the return code.

2 files changed, 4 insertions, 3 deletions

diff --git a/src/basic/socket-util.c b/src/basic/socket-util.c
index 1d43a48ae..151586479 100644
--- a/src/basic/socket-util.c
+++ b/src/basic/socket-util.c
@@ -481,7 +481,7 @@ bool socket_address_matches_fd(const SocketAddress *a, int fd) {
         return socket_address_equal(a, &b);
 }
 
-int sockaddr_port(const struct sockaddr *_sa) {
+int sockaddr_port(const struct sockaddr *_sa, unsigned *port) {
         union sockaddr_union *sa = (union sockaddr_union*) _sa;
 
         assert(sa);
@@ -489,7 +489,8 @@ int sockaddr_port(const struct sockaddr *_sa) {
         if (!IN_SET(sa->sa.sa_family, AF_INET, AF_INET6))
                 return -EAFNOSUPPORT;
 
-        return be16toh(sa->sa.sa_family == AF_INET6 ? sa->in6.sin6_port : sa->in.sin_port);
+        *port = be16toh(sa->sa.sa_family == AF_INET6 ? sa->in6.sin6_port : sa->in.sin_port);
+        return 0;
 }
 
 int sockaddr_pretty(const struct sockaddr *_sa, socklen_t salen, bool translate_ipv6, bool include_port, char **ret) {
diff --git a/src/basic/socket-util.h b/src/basic/socket-util.h
index 718de9ba3..b17c14189 100644
--- a/src/basic/socket-util.h
+++ b/src/basic/socket-util.h
@@ -103,7 +103,7 @@ const char* socket_address_get_path(const SocketAddress *a);
 bool socket_ipv6_is_supported(void);
 
 #if 0 /// UNNEEDED by elogind
-int sockaddr_port(const struct sockaddr *_sa) _pure_;
+int sockaddr_port(const struct sockaddr *_sa, unsigned *port) _pure_;
 
 int sockaddr_pretty(const struct sockaddr *_sa, socklen_t salen, bool translate_ipv6, bool include_port, char **ret);
 int getpeername_pretty(int fd, bool include_port, char **ret);