Bind bug in irserver's server.c
Posted: Mon 25. Jan 2010, 07:12There is a nasty bug in server.c for irserver where bind to a local socket is performed.
The line:
> if (bind (local_socket, (struct sockaddr *)&serv_addr_un, sizeof(serv_addr)) == -1
should be:
> if (bind (local_socket, (struct sockaddr *)&serv_addr_un, sizeof(serv_addr_un)) == -1
This because the serv_addr is actually of type sockaddr_in and is only used later in the code for binding to a tcp socket. The actual UNIX socket being used has an address of type sockaddr_un (albeit cast to struct sockaddr).
This bug becomes very apparent if you change the constant LIRCD definition to "/var/run/lirc/lircd" which is what default lirc clients expect these days (because on modern linux systems /dev is not really the appropriate place for applications to create filesystem sockets any more). If you do use "/var/run/lirc/lircd" then you will get a "Could not open IP socket" error. This is because the sizeof(serv_addr) is 16 and after subtracting the 4 bytes for sa_family this only leaves 12 bytes for the path. The proper sizeof(serv_addr_un) is 100 bytes.
The line:
> if (bind (local_socket, (struct sockaddr *)&serv_addr_un, sizeof(serv_addr)) == -1
should be:
> if (bind (local_socket, (struct sockaddr *)&serv_addr_un, sizeof(serv_addr_un)) == -1
This because the serv_addr is actually of type sockaddr_in and is only used later in the code for binding to a tcp socket. The actual UNIX socket being used has an address of type sockaddr_un (albeit cast to struct sockaddr).
This bug becomes very apparent if you change the constant LIRCD definition to "/var/run/lirc/lircd" which is what default lirc clients expect these days (because on modern linux systems /dev is not really the appropriate place for applications to create filesystem sockets any more). If you do use "/var/run/lirc/lircd" then you will get a "Could not open IP socket" error. This is because the sizeof(serv_addr) is 16 and after subtracting the 4 bytes for sa_family this only leaves 12 bytes for the path. The proper sizeof(serv_addr_un) is 100 bytes.