/**************************************************************************** * apps/netutils/pppd/ahdlc.c * Ahdlc receive and transmit processor for PPP engine. * * Version: 0.1 Original Version Jan 11, 1998 * Copyright (C) 1998, Mycal Labs www.mycal.com * Copyright (c) 2003, Mike Johnson, Mycal Labs, www.mycal.net * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by Mike Johnson/Mycal Labs * www.mycal.net. * 4. The name of the author may not be used to endorse or promote * products derived from this software without specific prior * written permission. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. * ****************************************************************************/ /**************************************************************************** * Included Files ****************************************************************************/ #include "ppp_conf.h" #include "ppp.h" /**************************************************************************** * Pre-processor Definitions ****************************************************************************/ #if PPP_DEBUG # define DEBUG1(x) debug_printf x # define PACKET_TX_DEBUG 1 #else # define DEBUG1(x) # define PACKET_TX_DEBUG 0 #endif /**************************************************************************** * Private Functions ****************************************************************************/ /**************************************************************************** * Simple and fast CRC16 routine for embedded processors. * * Just slightly slower than the table lookup method but consumes * almost no space. Much faster and smaller than the loop and * shift method that is widely used in the embedded space. * Can be optimized even more in .ASM * * data = (crcvalue ^ inputchar) & 0xff; * data = (data ^ (data << 4)) & 0xff; * crc = (crc >> 8) ^ ((data << 8) ^ (data <<3) ^ (data >> 4)) * ****************************************************************************/ static uint16_t crcadd(uint16_t crcvalue, uint8_t c) { uint16_t b; b = (crcvalue ^ c) & 0xFF; b = (b ^ (b << 4)) & 0xFF; b = (b << 8) ^ (b << 3) ^ (b >> 4); return ((crcvalue >> 8) ^ b); } /**************************************************************************** * Public Functions ****************************************************************************/ /**************************************************************************** * ahdlc_init(buffer, buffersize) - this initializes the ahdlc engine to * allow for rx frames. * ****************************************************************************/ void ahdlc_init(struct ppp_context_s *ctx) { ctx->ahdlc_flags = PPP_RX_ASYNC_MAP; ctx->ahdlc_rx_count = 0; ctx->ahdlc_tx_offline = 0; #ifdef PPP_STATISTICS ctx->ahdlc_crc_error = 0; ctx->ahdlc_rx_tobig_error = 0; #endif } /**************************************************************************** * ahdlc_rx_ready() - resets the ahdlc engine to the beginning of frame * state. * ****************************************************************************/ void ahdlc_rx_ready(struct ppp_context_s *ctx) { ctx->ahdlc_rx_count = 0; ctx->ahdlc_rx_crc = 0xffff; ctx->ahdlc_flags |= PPP_RX_READY; } /**************************************************************************** * ahdlc receive function - This routine processes incoming bytes and tries * to build a PPP frame. * * Two possible reasons that ahdlc_rx will not process characters: * o Buffer is locked - in this case ahdlc_rx returns 1, char * sending routing should retry. * ****************************************************************************/ uint8_t ahdlc_rx(FAR struct ppp_context_s *ctx, uint8_t c) { /* Check to see if PPP packet is useable, we should have hardware flow * control set, but if host ignores it and sends us a char when the PPP * Receive packet is in use, discard the character. */ if ((ctx->ahdlc_flags & PPP_RX_READY) != 0) { /* Check to see if character is less than 0x20 hex we really should set * AHDLC_RX_ASYNC_MAP on by default and only turn it off when it is * negotiated off to handle some buggy stacks. */ if ((c < 0x20) && ((ctx->ahdlc_flags & PPP_RX_ASYNC_MAP) == 0)) { /* Discard character */ DEBUG1(("Discard because char is < 0x20 hex and asysnc map is 0\n")); return 0; } /* Are we in escaped mode? */ if ((ctx->ahdlc_flags & PPP_ESCAPED) != 0) { /* Set escaped to FALSE */ ctx->ahdlc_flags &= ~PPP_ESCAPED; /* If value is 0x7e then silently discard and reset receive packet */ if (c == 0x7e) { ahdlc_rx_ready(ctx); return 0; } /* Incoming char = itself xor 20 */ c = c ^ 0x20; } else if (c == 0x7e) { /* Handle frame end */ if (ctx->ahdlc_rx_crc == CRC_GOOD_VALUE) { DEBUG1(("\nReceiving packet with good crc value, len %d\n", ctx->ahdlc_rx_count)); /* we have a good packet, turn off CTS until we are done with this * packet */ /* CTS_OFF(); */ #if PPP_STATISTICS /* Update statistics */ ++ctx->ppp_rx_frame_count; #endif /* Remove CRC bytes from packet */ ctx->ahdlc_rx_count -= 2; /* Lock PPP buffer */ ctx->ahdlc_flags &= ~PPP_RX_READY; /* upcall routine must fully process frame before return as * returning signifies that buffer belongs to AHDLC again. */ if ((ctx->ahdlc_rx_buffer[0] & 0x1) != 0 && (ctx->ahdlc_flags & PPP_PFC) != 0) { /* Send up packet */ ppp_upcall(ctx, (uint16_t)ctx->ahdlc_rx_buffer[0], (FAR uint8_t *) & ctx->ahdlc_rx_buffer[1], (uint16_t)(ctx->ahdlc_rx_count - 1)); } else { /* Send up packet */ ppp_upcall(ctx, (uint16_t)(ctx->ahdlc_rx_buffer[0] << 8 | ctx-> ahdlc_rx_buffer[1]), (FAR uint8_t *) & ctx->ahdlc_rx_buffer[2], (uint16_t)(ctx->ahdlc_rx_count - 2)); } ctx->ahdlc_tx_offline = 0; /* The remote side is alive */ ahdlc_rx_ready(ctx); return 0; } else if (ctx->ahdlc_rx_count > 3) { DEBUG1(("\nReceiving packet with bad crc value, was 0x%04x len %d\n", ctx->ahdlc_rx_crc, ctx->ahdlc_rx_count)); #ifdef PPP_STATISTICS ++ctx->ahdlc_crc_error; #endif /* Shouldn't we dump the packet and not pass it up? */ /* ppp_upcall((uint16_t)ahdlc_rx_buffer[0], (FAR uint8_t * *)&ahdlc_rx_buffer[0], (uint16_t)(ahdlc_rx_count+2)); * dump_ppp_packet(&ahdlc_rx_buffer[0],ahdlc_rx_count); */ } ahdlc_rx_ready(ctx); return 0; } else if (c == 0x7d) { /* Handle escaped chars */ ctx->ahdlc_flags |= PPP_ESCAPED; return 0; } /* Try to store char if not too big */ if (ctx->ahdlc_rx_count >= PPP_RX_BUFFER_SIZE) { #ifdef PPP_STATISTICS ++ctx->ahdlc_rx_tobig_error; #endif ahdlc_rx_ready(ctx); } else { /* Add CRC in */ ctx->ahdlc_rx_crc = crcadd(ctx->ahdlc_rx_crc, c); /* Do auto ACFC, if packet len is zero discard 0xff and 0x03 */ if (ctx->ahdlc_rx_count == 0) { if ((c == 0xff) || (c == 0x03)) { return 0; } } /* Store char */ ctx->ahdlc_rx_buffer[ctx->ahdlc_rx_count++] = c; } } else { /* we are busy and didn't process the character. */ DEBUG1(("Busy/not active\n")); return 1; } return 0; } /**************************************************************************** * ahdlc_tx_char(char) - write a character to the serial device, * escape if necessary. * * Relies on local global vars : ahdlc_tx_crc, ahdlc_flags. * Modifies local global vars : ahdlc_tx_crc. * ****************************************************************************/ void ahdlc_tx_char(struct ppp_context_s *ctx, uint16_t protocol, uint8_t c) { /* Add in crc */ ctx->ahdlc_tx_crc = crcadd(ctx->ahdlc_tx_crc, c); /* See if we need to escape char, we always escape 0x7d and 0x7e, in the case * of char < 0x20 we only support async map of default or none, so escape if * ASYNC map is not set. We may want to modify this to support a bitmap set * ASYNC map. */ if ((c == 0x7d) || (c == 0x7e) || ((c < 0x20) && ((protocol == LCP) || (ctx-> ahdlc_flags & PPP_TX_ASYNC_MAP) == 0))) { /* Send escape char and xor byte by 0x20 */ ppp_arch_putchar(ctx, 0x7d); c ^= 0x20; } ppp_arch_putchar(ctx, c); } /**************************************************************************** * ahdlc_tx(protocol,buffer,len) - Transmit a PPP frame. * * Buffer contains protocol data, ahdlc_tx adds address, control and * protocol data. * * Relies on local global vars : ahdlc_tx_crc, ahdlc_flags. * Modifies local global vars : ahdlc_tx_crc. * ****************************************************************************/ uint8_t ahdlc_tx(struct ppp_context_s *ctx, uint16_t protocol, FAR uint8_t * header, FAR uint8_t * buffer, uint16_t headerlen, uint16_t datalen) { uint16_t i; uint8_t c; DEBUG1(("\nAHDLC_TX - transmit frame, protocol 0x%04x, length %d offline %d\n", protocol, datalen + headerlen, ctx->ahdlc_tx_offline)); if (AHDLC_TX_OFFLINE && (ctx->ahdlc_tx_offline++ > AHDLC_TX_OFFLINE)) { ctx->ahdlc_tx_offline = 0; DEBUG1(("\nAHDLC_TX to many outstanding TX packets => ppp_reconnect()\n")); ppp_reconnect(ctx); return 0; } #if PACKET_TX_DEBUG DEBUG1(("\n")); for (i = 0; i < headerlen; ++i) { DEBUG1(("0x%02x ", header[i])); } for (i = 0; i < datalen; ++i) { DEBUG1(("0x%02x ", buffer[i])); } DEBUG1(("\n\n")); #endif /* Check to see that physical layer is up, we can assume is some cases */ /* Write leading 0x7e */ ppp_arch_putchar(ctx, 0x7e); /* Set initial CRC value */ ctx->ahdlc_tx_crc = 0xffff; /* send HDLC control and address if not disabled or of LCP frame type */ /* if ((0==(ahdlc_flags & PPP_ACFC)) || ((0xc0==buffer[0]) && * (0x21==buffer[1]))) */ if ((0 == (ctx->ahdlc_flags & PPP_ACFC)) || (protocol == LCP)) { ahdlc_tx_char(ctx, protocol, 0xff); ahdlc_tx_char(ctx, protocol, 0x03); } /* Write Protocol */ ahdlc_tx_char(ctx, protocol, (uint8_t)(protocol >> 8)); ahdlc_tx_char(ctx, protocol, (uint8_t)(protocol & 0xff)); /* Write header if it exists */ for (i = 0; i < headerlen; ++i) { /* Get next byte from buffer */ c = header[i]; /* Write it... */ ahdlc_tx_char(ctx, protocol, c); } /* Write frame bytes */ for (i = 0; i < datalen; ++i) { /* Get next byte from buffer */ c = buffer[i]; /* Write it... */ ahdlc_tx_char(ctx, protocol, c); } /* Send crc, lsb then msb */ i = ctx->ahdlc_tx_crc ^ 0xffff; ahdlc_tx_char(ctx, protocol, (uint8_t)(i & 0xff)); ahdlc_tx_char(ctx, protocol, (uint8_t)((i >> 8) & 0xff)); /* Write trailing 0x7e, probably not needed but it doesn't hurt */ ppp_arch_putchar(ctx, 0x7e); #if PPP_STATISTICS /* Update statistics */ ++ctx->ppp_tx_frame_count; #endif return 0; }