projects / dragonfly.git / blame
| Commit | Line | Data |
|---|---|---|
| 984263bc MD |
1 | /* |
| 2 | * | |
| 3 | * =================================== | |
| 4 | * HARP | Host ATM Research Platform | |
| 5 | * =================================== | |
| 6 | * | |
| 7 | * | |
| 8 | * This Host ATM Research Platform ("HARP") file (the "Software") is | |
| 9 | * made available by Network Computing Services, Inc. ("NetworkCS") | |
| 10 | * "AS IS". NetworkCS does not provide maintenance, improvements or | |
| 11 | * support of any kind. | |
| 12 | * | |
| 13 | * NETWORKCS MAKES NO WARRANTIES OR REPRESENTATIONS, EXPRESS OR IMPLIED, | |
| 14 | * INCLUDING, BUT NOT LIMITED TO, IMPLIED WARRANTIES OF MERCHANTABILITY | |
| 15 | * AND FITNESS FOR A PARTICULAR PURPOSE, AS TO ANY ELEMENT OF THE | |
| 16 | * SOFTWARE OR ANY SUPPORT PROVIDED IN CONNECTION WITH THIS SOFTWARE. | |
| 17 | * In no event shall NetworkCS be responsible for any damages, including | |
| 18 | * but not limited to consequential damages, arising from or relating to | |
| 19 | * any use of the Software or related support. | |
| 20 | * | |
| 21 | * Copyright 1994-1998 Network Computing Services, Inc. | |
| 22 | * | |
| 23 | * Copies of this Software may be made, however, the above copyright | |
| 24 | * notice must be reproduced on all copies. | |
| 25 | * | |
| 26 | * @(#) $FreeBSD: src/lib/libatm/ip_checksum.c,v 1.3.2.1 2001/09/28 16:52:10 dillon Exp $ | |
| 27 | * | |
| 28 | */ | |
| 29 | ||
| 984263bc MD |
30 | /* |
| 31 | * User Space Library Functions | |
| 32 | * ---------------------------- | |
| 33 | * | |
| 34 | * IP checksum computation | |
| 35 | * | |
| 36 | */ | |
| 37 | ||
| 38 | #include <sys/types.h> | |
| 39 | #include <sys/param.h> | |
| 40 | #include <sys/socket.h> | |
| 41 | #include <net/if.h> | |
| 42 | #include <netinet/in.h> | |
| 43 | #include <netatm/port.h> | |
| 44 | #include <netatm/atm.h> | |
| 45 | #include <netatm/atm_if.h> | |
| 46 | #include <netatm/atm_sap.h> | |
| 47 | #include <netatm/atm_sys.h> | |
| 48 | #include <netatm/atm_ioctl.h> | |
| 49 | ||
| 50 | #include "libatm.h" | |
| 51 | ||
| 52 | /* | |
| 53 | * Compute an IP checksum | |
| 54 | * | |
| 55 | * This code was taken from RFC 1071. | |
| 56 | * | |
| 57 | * "The following "C" code algorithm computes the checksum with an inner | |
| 58 | * loop that sums 16 bits at a time in a 32-bit accumulator." | |
| 59 | * | |
| 60 | * Arguments: | |
| 61 | * addr pointer to the buffer whose checksum is to be computed | |
| 62 | * count number of bytes to include in the checksum | |
| 63 | * | |
| 64 | * Returns: | |
| 65 | * the computed checksum | |
| 66 | * | |
| 67 | */ | |
| 68 | short | |
| d797dc5d | 69 | ip_checksum(char *addr, int count) |
| 984263bc MD |
70 | { |
| 71 | /* Compute Internet Checksum for "count" bytes | |
| 72 | * beginning at location "addr". | |
| 73 | */ | |
| 660c873b | 74 | long sum = 0; |
| 984263bc MD |
75 | |
| 76 | while( count > 1 ) { | |
| 77 | /* This is the inner loop */ | |
| 78 | sum += ntohs(* (unsigned short *) addr); | |
| 79 | addr += sizeof(unsigned short); | |
| 80 | count -= sizeof(unsigned short); | |
| 81 | } | |
| 82 | ||
| 83 | /* Add left-over byte, if any */ | |
| 84 | if( count > 0 ) | |
| 85 | sum += * (unsigned char *) addr; | |
| 86 | ||
| 87 | /* Fold 32-bit sum to 16 bits */ | |
| 88 | while (sum>>16) | |
| 89 | sum = (sum & 0xffff) + (sum >> 16); | |
| 90 | ||
| 91 | return((short)~sum); | |
| 92 | } |