tcpdump mailing list archives
Re: DLT_ request
From: Scott Deandrea <sdeandrea () apple com>
Date: Thu, 05 Jan 2017 21:59:01 -0800
The ioLength for a submitted request will the the amount of data requested in the data stage. The ioLength for a completed request will be the actual amount of data transferred in the data stage. It’s quite similar to any other data pipe. Just to note, it may be acceptable for a device to send less than the amount requested so the values may differ between a submit and a complete. For example, a usb ethernet driver could always perform reads of MTU sizes but the actual amount read will usually be less. —scott
On Jan 5, 2017, at 9:32 PM, Guy Harris <guy () alum mit edu> wrote: On Dec 9, 2016, at 1:37 PM, Scott Deandrea <sdeandrea () apple com> wrote:The link-layer header format is as follows: struct { // Control information uint16_t bcdVersion; // version of this structure uint8_t headerLength; // length of this structure uint8_t requestType; // tAppleUSBHostPacketFilterRequestType // Transfer information uint32_t ioLength; // amount of data requested/transferredSo, for a completed request - or a submitted request to the Default Control Pipe - does this have any relationship to the number of bytes of payload, or is the number of bytes of payload just "the on-the-wire length from the pcap/pcapng header minus the link-layer header length"? I.e., would checking that value against the actual number of bytes of payload in the packet, for completed requests and submitted request to the Default Control Pipe - be a useful error check, or should we just print that value without any interpretation or checking?
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Current thread:
- Re: DLT_ request, (continued)
- Re: DLT_ request Guy Harris (Jan 05)
- Re: DLT_ request Scott Deandrea (Jan 05)
- Re: DLT_ request Guy Harris (Jan 05)
- Re: DLT_ request Scott Deandrea (Jan 05)
- Re: DLT_ request Scott Deandrea (Jan 05)
- Re: DLT_ request Guy Harris (Jan 05)
- Re: DLT_ request Scott Deandrea (Jan 05)
- Re: DLT_ request Guy Harris (Jan 05)
- Re: DLT_ request Scott Deandrea (Jan 05)
- Re: DLT_ request Guy Harris (Jan 05)
- Re: DLT_ request Scott Deandrea (Jan 05)
- Re: DLT_ request Guy Harris (Jan 05)
- Re: DLT_ request Scott Deandrea (Jan 05)
- Re: DLT_ request Guy Harris (Jan 05)
- Re: DLT_ request Scott Deandrea (Jan 05)
- Re: DLT_ request Guy Harris (Jan 06)
- Re: DLT_ request Scott Deandrea (Jan 06)
- Re: DLT_ request Scott Deandrea (Jan 08)