On Fri, 12 Apr 2002, Edouard Gomez wrote:
>
> Hi,
>
> I'll take a look at the code this week end and will try to merge
> both sync and async stuff using a switch and function pointers.
> If you can do that before i hack it myself, it would be great :-)
>
Untested - done in my lunchbreak at work.
(IMO this needs some tidying up. Some of the #defines ought to
be moved into a separate header file. Maybe the FCS16 calc should
be in crc.c together with the fcstab (opinions?)
The static unsigned char header[4000]={FRAME_ADDR, FRAME_CTRL};
in ppp_write is a hack. It ought to be done better -
I think that the maximum size of this buffer is
n*2 + 2 + 4(ppp header) +2(FCS)
It is possible to have an MTU >1500 and this could probably be
exploited in a particularly perverse setup although it wouldn't
corrupt the stack so "standard" stack smashing attacks wouldn't
work.
Also, this is unlikely to look pretty in your editor.
I _always_ have my tabstop at 8 but I have my indent size at 4.
You will probably want to reindent my code to use tabs.
(I could do it but it's a principle thing ;-)
(seriously, I port code between dozens of systems at work and
unless you stick to fairly strict rules - tabs 8, indent 4,
lines <80 characters you can end up with code that is almost
impossible to edit on some systems - and I don't always get
the privilege of installing an editor - trying to edit code
via an intermittent dial up link to yugoslavia brings a whole
new meaning to the word difficult :-)
Tim.
Index: pppoa3.c
===================================================================
RCS file: /cvsroot/speedtouch/speedtouch/src/pppoa3.c,v
retrieving revision 1.20
diff -u -r1.20 pppoa3.c
--- pppoa3.c 20 Mar 2002 09:26:46 -0000 1.20
+++ pppoa3.c 12 Apr 2002 11:43:08 -0000
@@ -82,6 +82,78 @@
/* Some constants */
#include "pppoa3.h"
+static unsigned short 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
+};
+
+/**********************************************************************
+*%FUNCTION: pppFCS16
+*%ARGUMENTS:
+* fcs -- current fcs
+* cp -- a buffer's worth of data
+* len -- length of buffer "cp"
+*%RETURNS:
+* A new FCS
+*%DESCRIPTION:
+* Updates the PPP FCS.
+***********************************************************************/
+static unsigned short pppFCS16(unsigned short fcs,
+ unsigned char * cp,
+ int len)
+{
+ while (len--)
+ fcs = (fcs >> 8) ^ fcstab[(fcs ^ *cp++) & 0xff];
+
+ return (fcs);
+}
+
+/* States for scanning PPP frames */
+#define STATE_WAITFOR_FRAME_ADDR 0
+#define STATE_DROP_PROTO 1
+#define STATE_BUILDING_PACKET 2
+
+/* Special PPP frame characters */
+#define FRAME_ESC 0x7D
+#define FRAME_FLAG 0x7E
+#define FRAME_ADDR 0xFF
+#define FRAME_CTRL 0x03
+#define FRAME_ENC 0x20
+
+#define PPPINITFCS16 0xffff /* Initial FCS value */
+
+#define ASYNC_BUF_SIZE 1024
+
/******************************************************************************
* Local Prototypes
******************************************************************************/
@@ -208,8 +280,9 @@
/* Used when a thread needs to report a message in the logfile */
static pthread_mutex_t report_mutex;
+static int syncHDLC=1;
+
/* Reading and writing buffers */
-#define syncHDLC 1
#define BUFFER_SIZE (64*1024)
#define HDLC_HEADER_SIZE 2
@@ -490,6 +563,7 @@
if(isatty(STDIN_FILENO)) {
#ifdef N_HDLC
+ if(syncHDLC) {
int disc = N_HDLC;
if(ioctl(STDIN_FILENO, TIOCSETD, &disc) < 0) {
@@ -497,7 +571,7 @@
return(-1);
}
report(2, REPORT_DEBUG|REPORT_DATE, "N_HDLC line set up\n");
-
+ }
#elif defined TTYDISC
int disc = TTYDISC;
@@ -1065,8 +1139,6 @@
* sends to us. I use some code from rp-pppoe
*/
- int r;
-
if(size > BUFFER_SIZE) {
report(0, REPORT_ERROR|REPORT_DATE, "Error %d bytes requested but the
buffer is %d bytes long\n", size, BUFFER_SIZE);
return(0);
@@ -1074,20 +1146,22 @@
for(;;) {
- do {
- r = read(fd, buffer, size);
- } while(r < 0 && errno == EINTR);
+ /* supress leading 2 bytes */
+ if(syncHDLC) {
- if(r < 0) {
- report(0, REPORT_ERROR|REPORT_DATE|REPORT_PERROR, "Error
reading from pppd\n");
- return(-1);
- }
+ int r;
- if(!r)
- return(0);
+ do {
+ r = read(fd, buffer, size);
+ } while(r < 0 && errno == EINTR);
+
+ if(r < 0) {
+ report(0, REPORT_ERROR|REPORT_DATE|REPORT_PERROR,
+"Error reading from pppd\n");
+ return(-1);
+ }
- /* supress leading 2 bytes */
- if(syncHDLC) {
+ if(!r)
+ return(0);
if(r < 3) {
report(0, REPORT_ERROR|REPORT_DATE, "Read from ppp
short on data, r=%d => ignored\n", r);
@@ -1103,13 +1177,73 @@
}
else {
+ static int data=0;
+ static unsigned char async_buf[ASYNC_BUF_SIZE];
+ static unsigned char* ptr = async_buf;
+ static int PPPState=STATE_WAITFOR_FRAME_ADDR;
+ static int PPPPacketSize=0;
+ static int PPPXorValue=0;
+
+ if(!data) {
+ ptr = async_buf;
+
+ do {
+ data = read(fd, async_buf, ASYNC_BUF_SIZE);
+ } while(data < 0 && errno == EINTR);
+
+ if(data < 0) {
+ report(0, REPORT_ERROR|REPORT_DATE|REPORT_PERROR, "Error
+reading from pppd\n");
+ return(-1);
+ }
- report( 0, REPORT_ERROR|REPORT_DATE, "async HDLC not
handled\n");
+ if(!data)
+ return(0);
+ report(2, REPORT_DEBUG|REPORT_DATE|REPORT_DUMP, "PPP packet
+read from ppp(d) (%d bytes long)\n", async_buf, data, data);
+ }
+
+ /* ASSERT data>0 here */
+ --data;
+
+ if(PPPState == STATE_WAITFOR_FRAME_ADDR) {
+ if (*ptr++ == FRAME_ADDR) {
+ PPPState = STATE_DROP_PROTO;
+ PPPPacketSize = 0;
+ PPPXorValue = 0;
+ }
+ }
+
+ if(PPPState == STATE_DROP_PROTO) {
+ if (*ptr++ == (FRAME_CTRL ^ FRAME_ENC)) {
+ PPPState = STATE_BUILDING_PACKET;
+ }
+ }
+ /* Start building frame */
+ if(PPPState == STATE_BUILDING_PACKET) {
+ unsigned char c = *ptr++;
+ switch(c) {
+ case FRAME_ESC:
+ PPPXorValue = FRAME_ENC;
+ break;
+ case FRAME_FLAG:
+ PPPState = STATE_WAITFOR_FRAME_ADDR;
+ if (PPPPacketSize < 2) {
+ report(0, REPORT_ERROR|REPORT_DATE, "Read from ppp
+short on data, PPPPacketSize=%d => ignored\n", PPPPacketSize);
+ break;
+ }
+ return PPPPacketSize-2;
+ default:
+ if(PPPPacketSize == BUFFER_SIZE-HDLC_HEADER_SIZE) {
+ report(0, REPORT_ERROR|REPORT_DATE, "Read from ppp too
+much data, PPPPacketSize=%d => ignored\n", PPPPacketSize);
+ PPPState = STATE_WAITFOR_FRAME_ADDR;
+ break;
+ }
+ buffer[2+PPPPacketSize++] = c ^ PPPXorValue;
+ PPPXorValue = 0;
+ }
+ }
}
- break;
-
}
}
@@ -1164,7 +1298,53 @@
return(r);
}
else {
- report(0, REPORT_ERROR|REPORT_DATE, "async HDLC not handled\n");
+ static unsigned char header[4000]={FRAME_ADDR, FRAME_CTRL};
+ unsigned char tail[2];
+ unsigned char* ptr = header+2;
+ unsigned short fcs;
+ int i;
+ unsigned char c;
+ /* Compute FCS */
+ fcs = pppFCS16(PPPINITFCS16, header, 2);
+ fcs = pppFCS16(fcs, buffer+2, n-2) ^ 0xffff;
+ tail[0] = fcs & 0x00ff;
+ tail[1] = (fcs >> 8) & 0x00ff;
+
+ /* Build a buffer to send to PPP */
+ *ptr++ = FRAME_FLAG;
+ *ptr++ = FRAME_ADDR;
+ *ptr++ = FRAME_ESC;
+ *ptr++ = FRAME_CTRL ^ FRAME_ENC;
+
+ for (i=2; i<n; i++) {
+ c = buffer[i];
+ if (c == FRAME_FLAG || c == FRAME_ADDR || c == FRAME_ESC || c < 0x20) {
+ *ptr++ = FRAME_ESC;
+ *ptr++ = c ^ FRAME_ENC;
+ } else {
+ *ptr++ = c;
+ }
+ }
+ for (i=0; i<2; i++) {
+ c = tail[i];
+ if (c == FRAME_FLAG || c == FRAME_ADDR || c == FRAME_ESC || c < 0x20) {
+ *ptr++ = FRAME_ESC;
+ *ptr++ = c ^ FRAME_ENC;
+ } else {
+ *ptr++ = c;
+ }
+ }
+ *ptr++ = FRAME_FLAG;
+
+ /* Ship it out */
+ if ((r = write(fd, header, (ptr-header))) < 0) {
+ report(0, REPORT_ERROR|REPORT_DATE|REPORT_PERROR, "Error writing to
+ppp(d)\n");
+ }
+ else {
+ report(2, REPORT_DEBUG|REPORT_DATE|REPORT_DUMP, "PPP packet sent
+(%d)\n",header,(ptr-header),(ptr-header));
+ }
+
+ return r;
}
return(-1);
@@ -1508,6 +1688,9 @@
else if(strcmp(argv[i], "--pipehelp") == 0 || strcmp(argv[i], "-ph")
== 0) {
app_pipe_usage = 1;
app_exit = 1;
+ }
+ else if(strcmp(argv[i], "--async") == 0 || strcmp(argv[i], "-a") == 0)
+{
+ syncHDLC = 0;
}
else if(strcmp(argv[i], "--help") == 0 || strcmp(argv[i], "-h") == 0) {
app_usage = 1;
--
God said, "div D = rho, div B = 0, curl E = - @B/@t, curl H = J + @D/@t,"
and there was light.
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