libhw: net.h: Clarify UDP truncation behavior

2 files changed, 7 insertions, 1 deletions

diff --git a/libhw/common_include/libhw/generic/net.h b/libhw/common_include/libhw/generic/net.h
index 8dedaea..e23dcda 100644
--- a/libhw/common_include/libhw/generic/net.h
+++ b/libhw/common_include/libhw/generic/net.h
@@ -106,6 +106,11 @@ struct net_packet_conn_vtable {
 	ssize_t (*sendto  )(implements_net_packet_conn *self,
 	                    void *buf, size_t len,
 	                    struct net_ip4_addr node, uint16_t port);
+	/**
+	 * @return The full length of the message, which may be more
+	 * than the given `len` (as if the Linux MSG_TRUNC flag were
+	 * given).
+	 */
 	ssize_t (*recvfrom)(implements_net_packet_conn *self,
 	                    void *buf, size_t len,
 	                    struct net_ip4_addr *ret_node, uint16_t *ret_port);
diff --git a/libhw/host_net.c b/libhw/host_net.c
index 27df2e2..75486aa 100644
--- a/libhw/host_net.c
+++ b/libhw/host_net.c
@@ -457,7 +457,8 @@ static void *hostnet_pthread_recvfrom(void *_args) {
 	if (*(args->ret_size) < 0)
 		goto end;
 
-	*(args->ret_size) = recvfrom(args->connfd, args->buf, args->count, 0, &addr.gen, &addr_size);
+	*(args->ret_size) = recvfrom(args->connfd, args->buf, args->count,
+	                             MSG_TRUNC, &addr.gen, &addr_size);
 	if (*(args->ret_size) < 0)
 		goto end;