| /* |
| * Copyright (c) 1993, 1994, 1995, 1996, 1997 |
| * The Regents of the University of California. All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that: (1) source code distributions |
| * retain the above copyright notice and this paragraph in its entirety, (2) |
| * distributions including binary code include the above copyright notice and |
| * this paragraph in its entirety in the documentation or other materials |
| * provided with the distribution, and (3) all advertising materials mentioning |
| * features or use of this software display the following acknowledgement: |
| * ``This product includes software developed by the University of California, |
| * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of |
| * the University nor the names of its contributors may be used to endorse |
| * or promote products derived from this software without specific prior |
| * written permission. |
| * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED |
| * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF |
| * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. |
| * |
| * pcap-usb-linux-common.h - common code for everything that needs to |
| * deal with Linux USB captures, whether live or in a capture file; |
| * the later means that this is *not* Linux-only. |
| */ |
| |
| #include <limits.h> |
| |
| /* |
| * Return the sum of the two u_int arguments if that sum fits in a u_int, |
| * and return UINT_MAX otherwise. |
| */ |
| static inline u_int |
| u_int_sum(u_int a, u_int b) |
| { |
| return (((b) <= UINT_MAX - (a)) ? (a) + (b) : UINT_MAX); |
| } |
| |
| /* |
| * Is this a completion event for an isochronous transfer? |
| */ |
| static inline int |
| is_isochronous_transfer_completion(const pcap_usb_header_mmapped *hdr) |
| { |
| return (hdr->transfer_type == URB_ISOCHRONOUS && |
| hdr->event_type == URB_COMPLETE && |
| (hdr->endpoint_number & URB_TRANSFER_IN)); |
| } |
| |
| /* |
| * Total length of the pseudo-header, including the isochronous |
| * descriptors. |
| */ |
| static inline uint32_t |
| iso_pseudo_header_len(const pcap_usb_header_mmapped *usb_hdr) |
| { |
| return (sizeof(pcap_usb_header_mmapped) + |
| usb_hdr->ndesc * sizeof (usb_isodesc)); |
| } |
| |
| /* |
| * Calculate the packet length for a "this is complete" incoming |
| * isochronous transfer event. |
| * |
| * Calculating that from hdr->urb_len is not correct, because the |
| * data is not contiguous, and the isochroous descriptors show how |
| * it's scattered. |
| */ |
| static inline u_int |
| incoming_isochronous_transfer_completed_len(struct pcap_pkthdr *phdr, |
| const u_char *bp) |
| { |
| const pcap_usb_header_mmapped *hdr; |
| u_int bytes_left; |
| const usb_isodesc *descs; |
| u_int pre_truncation_data_len; |
| |
| /* |
| * All callers of this routine must ensure that pkth->caplen is |
| * >= sizeof (pcap_usb_header_mmapped). |
| */ |
| bytes_left = phdr->caplen; |
| bytes_left -= sizeof (pcap_usb_header_mmapped); |
| |
| hdr = (const pcap_usb_header_mmapped *) bp; |
| descs = (const usb_isodesc *) (bp + sizeof(pcap_usb_header_mmapped)); |
| |
| /* |
| * Find the end of the last chunk of data in the buffer |
| * referred to by the isochronous descriptors; that indicates |
| * how far into the buffer the data would have gone. |
| * |
| * Make sure we don't run past the end of the captured data |
| * while processing the isochronous descriptors. |
| */ |
| pre_truncation_data_len = 0; |
| for (uint32_t desc = 0; |
| desc < hdr->ndesc && bytes_left >= sizeof (usb_isodesc); |
| desc++, bytes_left -= sizeof (usb_isodesc)) { |
| u_int desc_end; |
| |
| if (descs[desc].len != 0) { |
| /* |
| * Compute the end offset of the data |
| * for this descriptor, i.e. the offset |
| * of the byte after the data. Clamp |
| * the sum at UINT_MAX, so that it fits |
| * in a u_int. |
| */ |
| desc_end = u_int_sum(descs[desc].offset, |
| descs[desc].len); |
| if (desc_end > pre_truncation_data_len) |
| pre_truncation_data_len = desc_end; |
| } |
| } |
| |
| /* |
| * Return the sum of the total header length (memory-mapped |
| * header and ISO descriptors) and the data length, clamped |
| * to UINT_MAX. |
| * |
| * We've made sure that the number of descriptors is |
| * <= USB_MAXDESC, so we know that the total size, |
| * in bytes, of the descriptors fits in a 32-bit |
| * integer. |
| */ |
| return (u_int_sum(iso_pseudo_header_len(hdr), pre_truncation_data_len)); |
| } |