Hi Marcel, Piotr, I completely agree with Piotr points. By the way, in my obexd patches, only when I start L2CAP connection or listen on L2CAP sock, I set the io mode to L2CAP_MODE_ERTM and the transfer mode to SOCK_SEQPACKET. When start RFCOMM connection or listen on RFCOMM sock, the io mode is still L2CAP_MODE_BASIC and the transfer mode is still SOCK_SEQPACKET. My patches support both OBEX OVER L2CAP and OBEX OVER RFCOMM. Best wishes. Nami -----Original Message----- From: linux-bluetooth-owner@xxxxxxxxxxxxxxx [mailto:linux-bluetooth-owner@xxxxxxxxxxxxxxx] On Behalf Of piotr.zgorecki@xxxxxxxxxxxxx Sent: 2011å6æ15æ 20:48 To: linux-bluetooth@xxxxxxxxxxxxxxx Cc: tim.howes@xxxxxxxxxxxxx Subject: RE: [PATCH 2/2] Bluetooth: FTP and OPP over L2CAP Hi Tim, Marcel, >> +enum obex_transport_format{ >> + OBEX_MT_STREAM , >> + OBEX_MT_SEQPACKET >> +}; >> + >> And more important, I have no idea why are you doing this anyway. >> Even with L2CAP this should run over SOCK_STREAM. > >Is that really so? I expect exposing L2CAP ERTM as a stream could break protocols above that >expect datagram-boundary preservation (eg RTP). Or can break protocols that mandate that >only one higher-layer packet exists in each L2CAP SDU. For these the socket needs to be >packet based. > >So, my surprise is that ERTM is exposed as SOCK_STREAM. So I do have an idea why the patch >mentions sequenced packet... > >> I assumed that OPP and FTP over L2CAP are requiring eL2CAP actually >> which is re-presented as a stream. > >Yes, OBEX over L2CAP requires enhanced retransmission mode. >From the Core Specification, Vol. 3, Part A, Pt. 7.3 Encapsulation of SDUs: "It is assumed that SDU boundaries shall be preserved between peer upper layer entities." SDU is by definition an abstraction exposed to the upper layer. This assumption permeates all of Bluetooth and breaking it can have dire consequences both for profiles assuming their messages map 1:1 to SDUs. Cheers, Piotr This message is for the designated recipient only and may contain privileged, proprietary, or otherwise private information. If you have received it in error, please notify the sender immediately and delete the original. Any other use of the email by you is prohibited. N r y b X Çv ^ )Þ{.n + { n[ - ) w*jg Ýj/ z Þ 2 Þ & )ß a G h j:+v w Ù ÿô.nlj·Ÿ®‰†+%ŠË±é¥Šwÿº{.nlj·¥Š{±ý¶ â^n‡r¡öë¨è&£ûz¹Þúzf£¢·hšˆ§~††Ûÿÿïÿ‘ê_èæ+v‰¨þ)ßø
