sd-bus: add sd_bus_message.verify_destination_id and .destination_ptr

kdbus learned to accept both a numerical destination ID as well as a
well-known-name. In that case, kdbus makes sure that the numerical ID is in
fact the owner of the provided name and fails otherwise.

This allows for race-free assertion of a bus name owner while sending a
message, which is a requirement for bus-proxyd.

Add two new fields to sd_bus_message, and set the numerical ID to
verify_destination_id if bus_message_setup_kmsg() is called for a
message with a well-known name.

Also, set the destination's name in the kdbus item to .destination_ptr
if it is non-NULL.

Normal users should not touch these fields, and they're not publicy
accessible.

1 files changed, 2 insertions, 0 deletions

diff --git a/src/libsystemd/sd-bus/bus-message.h b/src/libsystemd/sd-bus/bus-message.h
index df792945b0..8aa71fa1d8 100644
--- a/src/libsystemd/sd-bus/bus-message.h
+++ b/src/libsystemd/sd-bus/bus-message.h
@@ -100,6 +100,7 @@ struct sd_bus_message {
         usec_t realtime;
         uint64_t seqnum;
         int64_t priority;
+        uint64_t verify_destination_id;
 
         bool sealed:1;
         bool dont_send:1;
@@ -143,6 +144,7 @@ struct sd_bus_message {
 
         char sender_buffer[3 + DECIMAL_STR_MAX(uint64_t) + 1];
         char destination_buffer[3 + DECIMAL_STR_MAX(uint64_t) + 1];
+        char *destination_ptr;
 
         size_t header_offsets[_BUS_MESSAGE_HEADER_MAX];
         unsigned n_header_offsets;