[openbeosnetteam] Re: PPP & so on...
- From: "Nathan Whitehorn" <nathan.whitehorn@xxxxxxxxxxx>
- To: openbeosnetteam@xxxxxxxxxxxxx
- Date: Sat, 18 May 2002 14:47:52 EDT (-0400)
> BTW, if you have HDLC code then posting it here or a link to it would
> be a
> nice thing to do :)
But of course :) It's small, so I'll just attach it to the e-mail.
-Nathan
#include <string.h>
#include <debugger.h>
#include <stdio.h>
#include <SupportDefs.h>
#include "ppp_packet.h"
#include "fcs.h"
#include <ByteOrder.h>
#if ASSERTIONS
#include <assert.h>
#endif
#define verbose_assert(test,var)\
if (test) {\
char message[255];\
sprintf(message,"Test %s failed on line %d of file %s. Value of
%s is %d.",#test,__LINE__,__FILE__,#var,var);\
debugger(message);\
}
void PPPPacket::SetToAsyncFrame(const void *frame,size_t length,int32 clamp) {
uint8 *edit_buffer = new uint8[4096];
static int packets = 0;
int32 g = 0;
//verbose_assert(length < 5/*minimum PPP packet len*/,length);
for (int32 i = 4; i < length; i++) {
//----------Unescape----------
if (((uint8 *)(frame))[i] == 0x7e) {
if (g < 2)
return;
g -= 2;
break;
}
if (((uint8 *)(frame))[i] == 0x7d) {
i++;
edit_buffer[g] = ((uint8 *)(frame))[i] ^ 0x20;
} else
edit_buffer[g] = ((uint8 *)(frame))[i];
g++;
}
//verbose_assert((g < 2) || (g > 4096),g);
#if REM_MTU
if ((edit_buffer[0] == 0xc0) && (edit_buffer[1] == 0x21) &&
((edit_buffer[2] == 1) || (edit_buffer[2] == 3)) && (clamp > 0) && (packets <
20 /* If it doesn't stick after two packets, give up */)) {
uint8 payload [] = {0x01, 4, 0x00, 0x00};
uint16 len;
uint16 mru;
bool all_done = false;
memcpy(&len,&(edit_buffer[4]),2);
len = ntohs(len);
mru = htons(clamp);
memcpy(&(payload[2]),&mru,2);
#if ASSERTIONS
assert( len < g );
#endif
for (int32 i = 4; i < len; ) {
if (edit_buffer[i+2] == 1) {
memcpy(&(edit_buffer[i+4]),&mru,2);
all_done = true;
break;
}
i += edit_buffer[i+3];
}
if ((!all_done) && (edit_buffer[2] == 1)) {
memcpy(&(edit_buffer[len + 2]),payload,4);
len = htons(len + 4);
memcpy(&(edit_buffer[4]),&len,2);
g += 4;
}
packets++;
}
#endif
SetData(edit_buffer,g,0);
delete [] edit_buffer;
#if ASSERTIONS
assert(g < 4096);
#endif
}
size_t PPPPacket::GetAsyncFrame(const void *frame,size_t length,int32 clamp) {
uint8 *data = (uint8 *)(frame);
size_t size;
uint8 *edit_buffer = RawData(&size);
data[0] = 0x7e; //-----MagicCookies
data[1] = 0xff; //-----|
data[2] = 0x7d; //-----|
data[3] = 0x23; //-----|
uint8 little[2] = {0xff,0x03};
uint16 fcs = pppfcs16(PPPINITFCS16,little,2);
fcs = pppfcs16(fcs,edit_buffer,size);
fcs ^= 0xffff;
little[0] = fcs & 0x00ff;
little[1] = (fcs >> 8) & 0x00ff;
int32 g = 4;
for (int32 i = 0; i < size; i++) {
if ((edit_buffer[i] == 0x7e) || (edit_buffer[i] == 0x7d) ||
(edit_buffer[i] < 0x20)) {
data[g] = 0x7d;
g++;
data[g] = edit_buffer[i] ^ 0x20;
} else {
data[g] = edit_buffer[i];
}
g++;
}
for (int32 i = 0; i < 2; i++) {
if ((little[i] == 0x7e) || (little[i] == 0x7d) || (little[i] <
0x20)) {
data[g] = 0x7d;
g++;
data[g] = little[i] ^ 0x20;
} else {
data[g] = little[i];
}
g++;
}
size = g+1;
data[g] = 0x7e; //-----Frame termination
#if ASSERTIONS
assert(size < 4096);
#endif
return size;
}/*-----Lifted from RFC 1662,
PPP in HDLC-like Framing------------
http://www.faqs.org/rfcs/rfc1662.html
*/
/*
* u16 represents an unsigned 16-bit number. Adjust the typedef for
* your hardware.
*/
typedef uint16 u16;
/*
* FCS lookup table as calculated by the table generator.
*/
static u16 fcstab[256] = {
0x0000, 0x1189, 0x2312, 0x329b, 0x4624, 0x57ad, 0x6536, 0x74bf,
0x8c48, 0x9dc1, 0xaf5a, 0xbed3, 0xca6c, 0xdbe5, 0xe97e, 0xf8f7,
0x1081, 0x0108, 0x3393, 0x221a, 0x56a5, 0x472c, 0x75b7, 0x643e,
0x9cc9, 0x8d40, 0xbfdb, 0xae52, 0xdaed, 0xcb64, 0xf9ff, 0xe876,
0x2102, 0x308b, 0x0210, 0x1399, 0x6726, 0x76af, 0x4434, 0x55bd,
0xad4a, 0xbcc3, 0x8e58, 0x9fd1, 0xeb6e, 0xfae7, 0xc87c, 0xd9f5,
0x3183, 0x200a, 0x1291, 0x0318, 0x77a7, 0x662e, 0x54b5, 0x453c,
0xbdcb, 0xac42, 0x9ed9, 0x8f50, 0xfbef, 0xea66, 0xd8fd, 0xc974,
0x4204, 0x538d, 0x6116, 0x709f, 0x0420, 0x15a9, 0x2732, 0x36bb,
0xce4c, 0xdfc5, 0xed5e, 0xfcd7, 0x8868, 0x99e1, 0xab7a, 0xbaf3,
0x5285, 0x430c, 0x7197, 0x601e, 0x14a1, 0x0528, 0x37b3, 0x263a,
0xdecd, 0xcf44, 0xfddf, 0xec56, 0x98e9, 0x8960, 0xbbfb, 0xaa72,
0x6306, 0x728f, 0x4014, 0x519d, 0x2522, 0x34ab, 0x0630, 0x17b9,
0xef4e, 0xfec7, 0xcc5c, 0xddd5, 0xa96a, 0xb8e3, 0x8a78, 0x9bf1,
0x7387, 0x620e, 0x5095, 0x411c, 0x35a3, 0x242a, 0x16b1, 0x0738,
0xffcf, 0xee46, 0xdcdd, 0xcd54, 0xb9eb, 0xa862, 0x9af9, 0x8b70,
0x8408, 0x9581, 0xa71a, 0xb693, 0xc22c, 0xd3a5, 0xe13e, 0xf0b7,
0x0840, 0x19c9, 0x2b52, 0x3adb, 0x4e64, 0x5fed, 0x6d76, 0x7cff,
0x9489, 0x8500, 0xb79b, 0xa612, 0xd2ad, 0xc324, 0xf1bf, 0xe036,
0x18c1, 0x0948, 0x3bd3, 0x2a5a, 0x5ee5, 0x4f6c, 0x7df7, 0x6c7e,
0xa50a, 0xb483, 0x8618, 0x9791, 0xe32e, 0xf2a7, 0xc03c, 0xd1b5,
0x2942, 0x38cb, 0x0a50, 0x1bd9, 0x6f66, 0x7eef, 0x4c74, 0x5dfd,
0xb58b, 0xa402, 0x9699, 0x8710, 0xf3af, 0xe226, 0xd0bd, 0xc134,
0x39c3, 0x284a, 0x1ad1, 0x0b58, 0x7fe7, 0x6e6e, 0x5cf5, 0x4d7c,
0xc60c, 0xd785, 0xe51e, 0xf497, 0x8028, 0x91a1, 0xa33a, 0xb2b3,
0x4a44, 0x5bcd, 0x6956, 0x78df, 0x0c60, 0x1de9, 0x2f72, 0x3efb,
0xd68d, 0xc704, 0xf59f, 0xe416, 0x90a9, 0x8120, 0xb3bb, 0xa232,
0x5ac5, 0x4b4c, 0x79d7, 0x685e, 0x1ce1, 0x0d68, 0x3ff3, 0x2e7a,
0xe70e, 0xf687, 0xc41c, 0xd595, 0xa12a, 0xb0a3, 0x8238, 0x93b1,
0x6b46, 0x7acf, 0x4854, 0x59dd, 0x2d62, 0x3ceb, 0x0e70, 0x1ff9,
0xf78f, 0xe606, 0xd49d, 0xc514, 0xb1ab, 0xa022, 0x92b9, 0x8330,
0x7bc7, 0x6a4e, 0x58d5, 0x495c, 0x3de3, 0x2c6a, 0x1ef1, 0x0f78
};
#define PPPINITFCS16 0xffff /* Initial FCS value */
#define PPPGOODFCS16 0xf0b8 /* Good final FCS value */
/*
* Calculate a new fcs given the current fcs and the new data.
*/
u16 pppfcs16(u16 fcs, unsigned char *cp, int len)
{
while (len--)
fcs = (fcs >> 8) ^ fcstab[(fcs ^ *cp++) & 0xff];
return (fcs);
}
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