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serval-dna/slip.c
gardners 2252fdcaa7 created tool for automatically finding IN()s without matching 
OUT()s or where return() is used instead of RETURN().
Added OUT() to end of all functions using IN() that lacked it to
make it easier to statically analyse this invariant.
Fixed several return instead of RETURNs detected through use of
this tool. #49
2013-02-20 16:18:56 +10:30

444 lines
14 KiB
C
Raw Blame History

#include "serval.h"
#include "conf.h"
#include "log.h"
/* SLIP-style escape characters used for serial packet radio interfaces */
#define SLIP_END 0xc0
#define SLIP_ESC 0xdb
#define SLIP_0a 0x0a
#define SLIP_0d 0x0d
#define SLIP_0f 0x0f
#define SLIP_1b 0x1b
#define SLIP_ESC_END 0xdc
#define SLIP_ESC_ESC 0xdd
#define SLIP_ESC_0a 0x7a
#define SLIP_ESC_0d 0x7d
#define SLIP_ESC_0f 0x7f
#define SLIP_ESC_1b 0x6b
/* interface decoder state bits */
#define DC_VALID 1
#define DC_ESC 2
int slip_encode(int format,
unsigned char *src, int src_bytes, unsigned char *dst, int dst_len)
{
switch(format) {
case SLIP_FORMAT_SLIP:
{
int offset=0;
int i;
if (offset+2>dst_len)
return WHY("Dest buffer full");
dst[offset++]=SLIP_END;
uint32_t crc=Crc32_ComputeBuf( 0, src, src_bytes);
// (I'm assuming there are 4 extra bytes in memory here, which is very naughty...)
write_uint32(src+src_bytes, crc);
for (i=0;i<src_bytes+4;i++){
if (offset+3>dst_len)
return WHY("Dest buffer full");
switch(src[i]) {
case SLIP_END:
dst[offset++]=SLIP_ESC;
dst[offset++]=SLIP_ESC_END;
break;
case SLIP_ESC:
dst[offset++]=SLIP_ESC;
dst[offset++]=SLIP_ESC_ESC;
break;
case SLIP_0a:
dst[offset++]=SLIP_ESC;
dst[offset++]=SLIP_ESC_0a;
break;
case SLIP_0d:
dst[offset++]=SLIP_ESC;
dst[offset++]=SLIP_ESC_0d;
break;
case SLIP_0f:
dst[offset++]=SLIP_ESC;
dst[offset++]=SLIP_ESC_0f;
break;
case SLIP_1b:
dst[offset++]=SLIP_ESC;
dst[offset++]=SLIP_ESC_1b;
break;
default:
dst[offset++]=src[i];
}
}
dst[offset++]=SLIP_END;
return offset;
}
case SLIP_FORMAT_UPPER7:
/*
The purpose of this encoder is to work nicely with the RFD900 radios,
including allowing the reception of RSSI information in the middle of
packets.
RSSI reports look like:
L/R RSSI: 48/0 L/R noise: 62/0 pkts: 0 txe=0 rxe=0 stx=0 srx=0 ecc=0/0 temp=21 dco=0
So we are using 0x80-0xff to hold data, and { and } to frame packets.
*/
if (config.debug.slip)
dump("pre-slipped packet",src,src_bytes);
{
if (src_bytes<1) return 0;
if (src_bytes>0x3fff)
return WHYF("UPPER7 SLIP encoder packets must be <=0x3fff bytes");
if (dst_len<(9+src_bytes+(src_bytes/7)+1))
return WHYF("UPPER7 SLIP encoder requires 9+(8/7)*bytes to encode");
int i,j;
int out_len=0;
// Start of packet marker
dst[out_len++]='{';
// Length of (unencoded) packet
dst[out_len++]=0x80+((src_bytes>>7)&0x7f);
dst[out_len++]=0x80+((src_bytes>>0)&0x7f);
// Add 32-bit CRC
// (putting the CRC at the front allows it to be calculated progressively
// on the receiver side, if we decide to support that)
unsigned long crc=Crc32_ComputeBuf( 0, src, src_bytes);
dst[out_len++]=0x80|((crc>>25)&0x7f);
dst[out_len++]=0x80|((crc>>(25-7))&0x7f);
dst[out_len++]=0x80|((crc>>(25-7-7))&0x7f);
dst[out_len++]=0x80|((crc>>(25-7-7-7))&0x7f);
dst[out_len++]=0x80|((crc>>0)&0x7f);
for(i=0;i<src_bytes;i+=7)
{
// Create 8 bytes of output consisting of 8x7 bits
// Generate vector of 7 bytes to encode
unsigned char v[7];
for(j=0;j<7&&i+j<src_bytes;j++) v[j]=src[i+j];
for(;j<7;j++) v[j]=0;
if (out_len+8>dst_len)
return WHYF("Ran out of space in UPPER7 SLIP encoder (used all %d bytes after encoding %d of %d bytes)",
dst_len,i,src_bytes);
// We could use a nice for loop to do this, but for 8 bytes, let's
// just do it explicitly.
dst[out_len++]=0x80| (v[0]>>1);
dst[out_len++]=0x80|((v[0]&0x01)<<6)|(v[1]>>2);
dst[out_len++]=0x80|((v[1]&0x03)<<5)|(v[2]>>3);
dst[out_len++]=0x80|((v[2]&0x07)<<4)|(v[3]>>4);
dst[out_len++]=0x80|((v[3]&0x0f)<<3)|(v[4]>>5);
dst[out_len++]=0x80|((v[4]&0x1f)<<2)|(v[5]>>6);
dst[out_len++]=0x80|((v[5]&0x3f)<<1)|(v[6]>>7);
dst[out_len++]=0x80|((v[6]&0x7f)<<0);
}
// Mark end of packet
dst[out_len++]='}';
// Detect fatal miscalculations on byte counts
if (out_len>dst_len) {
FATALF("overran output buffer in SLIP UPPER7 encapsulation of packet (used %d of %d bytes)",out_len,dst_len);
}
return out_len;
}
default:
return WHYF("Unsupported slip encoding #%d",format);
}
}
unsigned long long last_rssi_time=0;
int last_radio_rssi=-999;
int last_radio_temperature=-999;
int parse_rfd900_rssi(char *s)
{
int lrssi,rrssi,lnoise,rnoise,temp;
// L/R RSSI: 48/0 L/R noise: 62/0 pkts: 0 txe=0 rxe=0 stx=0 srx=0 ecc=0/0 temp=21 dco=0
if (sscanf(s,"L/R RSSI: %d/%d L/R noise: %d/%d pkts: %*d txe=%*d rxe=%*d stx=%*d srx=%*d ecc=%*d/%*d temp=%d dco=%*d",
&lrssi,&rrssi,&lnoise,&rnoise,&temp)==5)
{
int lmargin=(lrssi-lnoise)/1.9;
int rmargin=(lrssi-lnoise)/1.9;
int maxmargin=lmargin; if (rmargin>maxmargin) maxmargin=rmargin;
last_radio_rssi=maxmargin;
last_radio_temperature=temp;
if (config.debug.packetradio||(gettime_ms()-last_rssi_time>30000)) {
INFOF("Link budget = %+ddB, temperature=%dC",maxmargin,temp);
last_rssi_time=gettime_ms();
}
}
return 0;
}
#define UPPER7_STATE_NOTINPACKET 0
#define UPPER7_STATE_L1 1
#define UPPER7_STATE_L2 2
#define UPPER7_STATE_C1 3
#define UPPER7_STATE_C2 4
#define UPPER7_STATE_C3 5
#define UPPER7_STATE_C4 6
#define UPPER7_STATE_C5 7
#define UPPER7_STATE_D0 8
#define UPPER7_STATE_D1 9
#define UPPER7_STATE_D2 10
#define UPPER7_STATE_D3 11
#define UPPER7_STATE_D4 12
#define UPPER7_STATE_D5 13
#define UPPER7_STATE_D6 14
#define UPPER7_STATE_D7 15
int u7d_calls=0;
int upper7_decode(struct slip_decode_state *state,unsigned char byte)
{
IN()
u7d_calls++;
if (config.debug.slipdecode)
snprintf(crash_handler_clue,1024,
"upper7_decode() call #%d: state=%d, byte=0x%02x, rssi_len=%d, dst_offset=%d",
u7d_calls,state->state,byte,state->rssi_len,state->dst_offset);
// Parse out inline RSSI reports
if (byte=='{') {
state->state=UPPER7_STATE_L1;
state->packet_length=0;
RETURN(0);
} else if (byte=='}') {
// End of packet marker -- report end of received packet to caller
// for CRC verification etc.
state->state=UPPER7_STATE_NOTINPACKET; RETURN(1);
} else if (byte>=' '&&byte<=0x7f) {
if (state->rssi_len<0) state->rssi_len=0;
if (state->rssi_len<RSSI_TEXT_SIZE)
state->rssi_text[state->rssi_len++]=byte;
RETURN(0);
} else if (byte=='\r'||byte=='\n') {
if (state->rssi_len>=RSSI_TEXT_SIZE) state->rssi_len=RSSI_TEXT_SIZE-1;
if (state->rssi_len<0) state->rssi_len=0;
state->rssi_text[state->rssi_len]=0;
parse_rfd900_rssi(state->rssi_text);
state->rssi_len=0;
}
// Non-data bytes (none currently used, but we need to catch them before
// moving onto processing data bytes)
if (byte<0x80) {
RETURN(0);
}
// Data bytes and packet fields
byte&=0x7f;
if (state->packet_length>=OVERLAY_INTERFACE_RX_BUFFER_SIZE
||(state->dst_offset+7)>=OVERLAY_INTERFACE_RX_BUFFER_SIZE
||state->dst_offset<0)
{
WARNF("state=%p, state->dst_offset=%d, ->packet_length=%d, ->state=%d. State reset.",
state,state->dst_offset,state->packet_length,state->state);
state->state=UPPER7_STATE_NOTINPACKET;
state->dst_offset=0;
state->packet_length=0;
RETURN(0);
}
switch(state->state) {
case UPPER7_STATE_NOTINPACKET: RETURN(0);
case UPPER7_STATE_L1: state->packet_length=byte<<7; state->state++; RETURN(0);
case UPPER7_STATE_L2: state->packet_length|=byte;
// Make sure packet length can fit in RX buffer, including that we might
// need upto 7 bytes extra temporary space due to blocking
if ((state->packet_length+7)<OVERLAY_INTERFACE_RX_BUFFER_SIZE) {
state->state++;
state->dst_offset=0;
} else {
if (config.debug.packetradio)
DEBUGF("Ignoring jumbo packet of %d bytes",state->packet_length);
state->state=UPPER7_STATE_NOTINPACKET;
}
RETURN(0);
case UPPER7_STATE_C1: state->crc=byte<<25; state->state++; RETURN(0);
case UPPER7_STATE_C2: state->crc|=byte<<(25-7); state->state++; RETURN(0);
case UPPER7_STATE_C3: state->crc|=byte<<(25-7-7); state->state++; RETURN(0);
case UPPER7_STATE_C4: state->crc|=byte<<(25-7-7-7); state->state++; RETURN(0);
case UPPER7_STATE_C5: state->crc|=byte<<0; state->state++; RETURN(0);
case UPPER7_STATE_D0:
if (state->packet_length>=OVERLAY_INTERFACE_RX_BUFFER_SIZE
||(state->dst_offset+7)>=OVERLAY_INTERFACE_RX_BUFFER_SIZE
||state->dst_offset<0)
{
WARNF("state->dst_offset=%d, ->packet_length=%d, ->state=%d. State reset (again).",
state->dst_offset,state->packet_length,state->state);
state->state=UPPER7_STATE_NOTINPACKET;
state->dst_offset=0;
state->packet_length=0;
RETURN(0);
}
state->dst[state->dst_offset]=byte<<1;
state->state++;
RETURN(0);
case UPPER7_STATE_D1:
state->dst[state->dst_offset+0]|=(byte>>6)&0x01;
state->dst[state->dst_offset+1]=(byte<<2);
state->state++;
RETURN(0);
case UPPER7_STATE_D2:
state->dst[state->dst_offset+1]|=(byte>>5)&0x03;
state->dst[state->dst_offset+2]=(byte<<3);
state->state++;
RETURN(0);
case UPPER7_STATE_D3:
state->dst[state->dst_offset+2]|=(byte>>4)&0x07;
state->dst[state->dst_offset+3]=(byte<<4);
state->state++;
RETURN(0);
case UPPER7_STATE_D4:
state->dst[state->dst_offset+3]|=(byte>>3)&0x0f;
state->dst[state->dst_offset+4]=(byte<<5);
state->state++;
RETURN(0);
case UPPER7_STATE_D5:
state->dst[state->dst_offset+4]|=(byte>>2)&0x1f;
state->dst[state->dst_offset+5]=(byte<<6);
state->state++;
RETURN(0);
case UPPER7_STATE_D6:
state->dst[state->dst_offset+5]|=(byte>>1)&0x3f;
state->dst[state->dst_offset+6]=(byte<<7);
state->state++;
RETURN(0);
case UPPER7_STATE_D7:
state->dst[state->dst_offset+6]|=(byte>>0)&0x7f;
state->dst_offset+=7;
state->state=UPPER7_STATE_D0;
RETURN(0);
default:
state->state=UPPER7_STATE_NOTINPACKET;
RETURN(0);
}
OUT();
}
/* state->src and state->src_size contain the freshly read bytes
we must accumulate any partial state between calls.
*/
int slip_decode(struct slip_decode_state *state)
{
switch(state->encapsulator) {
case SLIP_FORMAT_SLIP:
{
/*
Examine received bytes for end of packet marker.
The challenge is that we need to make sure that the packet encapsulation
is self-synchronising in the event that a data error occurs (including
failure to receive an arbitrary number of bytes).
*/
while(state->src_offset < state->src_size){
// clear the valid bit flag if we hit the end of the destination buffer
if (state->dst_offset>=sizeof(state->dst))
state->state&=~DC_VALID;
if (state->state&DC_ESC){
// clear escape bit
state->state&=~DC_ESC;
switch(state->src[state->src_offset]) {
case SLIP_ESC_END: // escaped END byte
state->dst[state->dst_offset++]=SLIP_END;
break;
case SLIP_ESC_ESC: // escaped escape character
state->dst[state->dst_offset++]=SLIP_ESC;
break;
case SLIP_ESC_0a:
state->dst[state->dst_offset++]=SLIP_0a;
break;
case SLIP_ESC_0d:
state->dst[state->dst_offset++]=SLIP_0d;
break;
case SLIP_ESC_0f:
state->dst[state->dst_offset++]=SLIP_0f;
break;
case SLIP_ESC_1b:
state->dst[state->dst_offset++]=SLIP_1b;
break;
default: /* Unknown escape character. This is an error. */
if (config.debug.packetradio)
WARNF("Packet radio stream contained illegal escaped byte 0x%02x -- resetting parser.",state->src[state->src_offset]);
state->dst_offset=0;
// skip everything until the next SLIP_END
state->state=0;
}
}else{
// non-escape character
switch(state->src[state->src_offset]) {
case SLIP_ESC:
// set escape bit
state->state|=DC_ESC;
break;
case SLIP_END:
if (state->dst_offset>4){
uint32_t src_crc = read_uint32(state->dst + state->dst_offset -4);
uint32_t crc=Crc32_ComputeBuf( 0, state->dst, state->dst_offset -4);
if (src_crc != crc){
DEBUGF("Dropping frame due to CRC failure (%08x vs %08x)", src_crc, crc);
dump("frame", state->dst, state->dst_offset);
state->dst_offset=0;
state->state=0;
break;
}
// return once we've successfully parsed a valid packet that isn't empty
state->packet_length=state->dst_offset -4;
return 1;
}
// set the valid flag to begin parsing the next packet
state->state=DC_VALID;
break;
default:
if (state->state&DC_VALID)
state->dst[state->dst_offset++]=state->src[state->src_offset];
}
}
state->src_offset++;
}
return 0;
}
case SLIP_FORMAT_UPPER7:
{
if (config.debug.slip) {
if (state->rssi_len<0) state->rssi_len=0;
if (state->rssi_len>=RSSI_TEXT_SIZE) state->rssi_len=RSSI_TEXT_SIZE-1;
state->rssi_text[state->rssi_len]=0;
DEBUGF("RX state=%d, rssi_len=%d, rssi_text='%s',src=%p, src_size=%d",
state->state,state->rssi_len,state->rssi_text,
state->src,state->src_size);
}
while(state->src_offset<state->src_size) {
if (upper7_decode(state,state->src[state->src_offset++])==1) {
if (config.debug.slip) {
dump("de-slipped packet",state->dst,state->packet_length);
}
// Check that CRC matches
uint32_t crc=Crc32_ComputeBuf( 0, state->dst, state->packet_length);
if (crc!=state->crc) {
if (config.debug.packetradio||config.debug.rejecteddata)
DEBUGF("Rejected packet of %d bytes due to CRC mis-match (%08x vs %08x)",
state->packet_length,crc,state->crc);
if (config.debug.rejecteddata) {
dump("bad packet",state->dst,state->packet_length);
}
} else {
if (config.debug.packetradio)
DEBUGF("Accepted packet of %d bytes (CRC ok)",state->packet_length);
return 1;
}
}
}
}
return 0;
default:
return WHYF("Unknown SLIP encapsulation format #%d",state->encapsulator);
}
}
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