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tio/src/xymodem.c
Martin Lund 51300cc4f0 Add timeout feature to expect()
2024-04-13 15:30:14 +02:00

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/*
* Minimalistic implementation of the xmodem-1k and ymodem sender protocol.
* https://en.wikipedia.org/wiki/XMODEM
* https://en.wikipedia.org/wiki/YMODEM
*
* SPDX-License-Identifier: GPL-2.0-or-later OR MIT-0
*
*/
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <sys/poll.h>
#include <termios.h>
#include "xymodem.h"
#include "print.h"
#define SOH 0x01
#define STX 0x02
#define ACK 0x06
#define NAK 0x15
#define CAN 0x18
#define EOT "\004"
#define OK 0
#define ERR (-1)
#define min(a, b) ((a) < (b) ? (a) : (b))
struct xpacket_1k {
uint8_t type;
uint8_t seq;
uint8_t nseq;
uint8_t data[1024];
uint8_t crc_hi;
uint8_t crc_lo;
} __attribute__((packed));
struct xpacket {
uint8_t type;
uint8_t seq;
uint8_t nseq;
uint8_t data[128];
uint8_t crc_hi;
uint8_t crc_lo;
} __attribute__((packed));
/* See https://en.wikipedia.org/wiki/Computation_of_cyclic_redundancy_checks */
static uint16_t crc16(const uint8_t *data, uint16_t size)
{
uint16_t crc, s;
for (crc = 0; size > 0; size--) {
s = *data++ ^ (crc >> 8);
s ^= (s >> 4);
crc = (crc << 8) ^ s ^ (s << 5) ^ (s << 12);
}
return crc;
}
static int xmodem_1k(int sio, const void *data, size_t len, int seq)
{
struct xpacket_1k packet;
const uint8_t *buf = data;
char resp = 0;
int rc, crc;
/* Drain pending characters from serial line. Insist on the
* last drained character being 'C'.
*/
while(1) {
if (key_hit)
return -1;
rc = read_poll(sio, &resp, 1, 50);
if (rc == 0) {
if (resp == 'C') break;
if (resp == CAN) return ERR;
continue;
}
else if (rc < 0) {
tio_error_print("Read sync from serial failed");
return ERR;
}
}
/* Always work with 1K packets */
packet.seq = seq;
packet.type = STX;
while (len) {
size_t sz, z = 0;
char *from, status;
/* Build next packet, pad with 0 to full seq */
z = min(len, sizeof(packet.data));
memcpy(packet.data, buf, z);
memset(packet.data + z, 0, sizeof(packet.data) - z);
crc = crc16(packet.data, sizeof(packet.data));
packet.crc_hi = crc >> 8;
packet.crc_lo = crc;
packet.nseq = 0xff - packet.seq;
/* Send packet */
from = (char *) &packet;
sz = sizeof(packet);
while (sz) {
if (key_hit)
return ERR;
if ((rc = write(sio, from, sz)) < 0 ) {
if (errno == EWOULDBLOCK) {
usleep(1000);
continue;
}
tio_error_print("Write packet to serial failed");
return ERR;
}
from += rc;
sz -= rc;
}
/* Clear response */
resp = 0;
/* 'lrzsz' does not ACK ymodem's fin packet */
if (seq == 0 && packet.data[0] == 0) resp = ACK;
/* Read receiver response, timeout 1 s */
for(int n=0; n < 20; n++) {
if (key_hit)
return ERR;
rc = read_poll(sio, &resp, 1, 50);
if (rc < 0) {
tio_error_print("Read ack/nak from serial failed");
return ERR;
} else if(rc > 0) {
break;
}
}
/* Update "progress bar" */
switch (resp) {
case NAK: status = 'N'; break;
case ACK: status = '.'; break;
case 'C': status = 'C'; break;
case CAN: status = '!'; return ERR;
default: status = '?';
}
write(STDOUT_FILENO, &status, 1);
/* Move to next block after ACK */
if (resp == ACK) {
packet.seq++;
len -= z;
buf += z;
}
}
/* Send EOT at 1 Hz until ACK or CAN received */
while (seq) {
if (key_hit)
return ERR;
if (write(sio, EOT, 1) < 0) {
tio_error_print("Write EOT to serial failed");
return ERR;
}
write(STDOUT_FILENO, "|", 1);
/* 1s timeout */
rc = read_poll(sio, &resp, 1, 1000);
if (rc < 0) {
tio_error_print("Read from serial failed");
return ERR;
} else if(rc == 0) {
continue;
}
if (resp == ACK || resp == CAN) {
write(STDOUT_FILENO, "\r\n", 2);
return (resp == ACK) ? OK : ERR;
}
}
return 0; /* not reached */
}
static int xmodem(int sio, const void *data, size_t len)
{
struct xpacket packet;
const uint8_t *buf = data;
char resp = 0;
int rc, crc;
/* Drain pending characters from serial line. Insist on the
* last drained character being 'C'.
*/
while(1) {
if (key_hit)
return -1;
rc = read_poll(sio, &resp, 1, 50);
if (rc == 0) {
if (resp == 'C') break;
if (resp == CAN) return ERR;
continue;
}
else if (rc < 0) {
tio_error_print("Read sync from serial failed");
return ERR;
}
}
/* Always work with 128b packets */
packet.seq = 1;
packet.type = SOH;
while (len) {
size_t sz, z = 0;
char *from, status;
/* Build next packet, pad with 0 to full seq */
z = min(len, sizeof(packet.data));
memcpy(packet.data, buf, z);
memset(packet.data + z, 0, sizeof(packet.data) - z);
crc = crc16(packet.data, sizeof(packet.data));
packet.crc_hi = crc >> 8;
packet.crc_lo = crc;
packet.nseq = 0xff - packet.seq;
/* Send packet */
from = (char *) &packet;
sz = sizeof(packet);
while (sz) {
if (key_hit)
return ERR;
if ((rc = write(sio, from, sz)) < 0 ) {
if (errno == EWOULDBLOCK) {
usleep(1000);
continue;
}
tio_error_print("Write packet to serial failed");
return ERR;
}
from += rc;
sz -= rc;
}
/* Clear response */
resp = 0;
/* Read receiver response, timeout 1 s */
for(int n=0; n < 20; n++) {
if (key_hit)
return ERR;
rc = read_poll(sio, &resp, 1, 50);
if (rc < 0) {
tio_error_print("Read ack/nak from serial failed");
return ERR;
} else if(rc > 0) {
break;
}
}
/* Update "progress bar" */
switch (resp) {
case NAK: status = 'N'; break;
case ACK: status = '.'; break;
case 'C': status = 'C'; break;
case CAN: status = '!'; return ERR;
default: status = '?';
}
write(STDOUT_FILENO, &status, 1);
/* Move to next block after ACK */
if (resp == ACK) {
packet.seq++;
len -= z;
buf += z;
}
}
/* Send EOT at 1 Hz until ACK or CAN received */
while (1) {
if (key_hit)
return ERR;
if (write(sio, EOT, 1) < 0) {
tio_error_print("Write EOT to serial failed");
return ERR;
}
write(STDOUT_FILENO, "|", 1);
/* 1s timeout */
rc = read_poll(sio, &resp, 1, 1000);
if (rc < 0) {
tio_error_print("Read from serial failed");
return ERR;
} else if(rc == 0) {
continue;
}
if (resp == ACK || resp == CAN) {
write(STDOUT_FILENO, "\r\n", 2);
return (resp == ACK) ? OK : ERR;
}
}
return 0; /* not reached */
}
int xymodem_send(int sio, const char *filename, modem_mode_t mode)
{
size_t len;
int rc, fd;
struct stat stat;
const uint8_t *buf;
/* Open file, map into memory */
fd = open(filename, O_RDONLY);
if (fd < 0) {
tio_error_print("Could not open file");
return ERR;
}
fstat(fd, &stat);
len = stat.st_size;
buf = mmap(NULL, len, PROT_READ, MAP_PRIVATE, fd, 0);
if (!buf) {
close(fd);
tio_error_print("Could not mmap file");
return ERR;
}
/* Do transfer */
key_hit = 0;
if (mode == XMODEM_1K) {
rc = xmodem_1k(sio, buf, len, 1);
}
else if (mode == XMODEM_CRC) {
rc = xmodem(sio, buf, len);
}
else {
/* Ymodem: hdr + file + fin */
while(1) {
char hdr[1024], *p;
rc = -1;
if (strlen(filename) > 977) break; /* hdr block overrun */
p = stpcpy(hdr, filename) + 1;
p += sprintf(p, "%ld %lo %o", len, stat.st_mtime, stat.st_mode);
if (xmodem_1k(sio, hdr, p - hdr, 0) < 0) break; /* hdr with metadata */
if (xmodem_1k(sio, buf, len, 1) < 0) break; /* xmodem file */
if (xmodem_1k(sio, "", 1, 0) < 0) break; /* empty hdr = fin */
rc = 0; break;
}
}
key_hit = 0xff;
/* Flush serial and release resources */
tcflush(sio, TCIOFLUSH);
munmap((void *)buf, len);
close(fd);
return rc;
}
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