Added support to receive XMODEM-CRC files from the connected serial port.

src/tty.c

@@ -692,7 +692,7 @@ void handle_command_sequence(char input_char, char *output_char, bool *forward)
                         {
                             tio_printf("Sending file '%s'  ", line);
                             tio_printf("Press any key to abort transfer");
-                            tio_printf("%s", xymodem_send(device_fd, line, XMODEM_CRC) < 0 ? "Aborted" : "Done");
+                            tio_printf("%s", xymodem_send(device_fd, line, XMODEM_1K) < 0 ? "Aborted" : "Done");
                         }
                         break;
 
@@ -707,6 +707,17 @@ void handle_command_sequence(char input_char, char *output_char, bool *forward)
                         }
                         break;
 
+                    case KEY_2:
+                        tio_printf("Receive file with XMODEM-CRC");
+                        tio_printf_raw("Enter file name: ");
+                        if (tio_readln())
+                        {
+                            tio_printf("Ready to receiving file '%s'  ", line);
+                            tio_printf("Press any key to abort transfer");
+                            tio_printf("%s", xymodem_receive(device_fd, line, XMODEM_CRC) < 0 ? "Aborted" : "Done");
+                        }
+                        break;
+
                     default:
                         tio_error_print("Invalid protocol option");
                         break;
@@ -758,7 +769,7 @@ void handle_command_sequence(char input_char, char *output_char, bool *forward)
                 tio_printf(" ctrl-%c t       Toggle line timestamp mode", option.prefix_key);
                 tio_printf(" ctrl-%c U       Toggle conversion to uppercase on output", option.prefix_key);
                 tio_printf(" ctrl-%c v       Show version", option.prefix_key);
-                tio_printf(" ctrl-%c x       Send file via Xmodem", option.prefix_key);
+                tio_printf(" ctrl-%c x       Send/Receive file via Xmodem", option.prefix_key);
                 tio_printf(" ctrl-%c y       Send file via Ymodem", option.prefix_key);
                 tio_printf(" ctrl-%c ctrl-%c  Send ctrl-%c character", option.prefix_key, option.prefix_key, option.prefix_key);
                 break;
@@ -956,8 +967,9 @@ void handle_command_sequence(char input_char, char *output_char, bool *forward)
 
             case KEY_X:
                 tio_printf("Please enter which X modem protocol to use:");
-                tio_printf(" (0) XMODEM-1K");
-                tio_printf(" (1) XMODEM-CRC");
+                tio_printf(" (0) XMODEM-1K send");
+                tio_printf(" (1) XMODEM-CRC send");
+                tio_printf(" (2) XMODEM-CRC receive");
                 // Process next input character as sub command
                 sub_command = SUBCOMMAND_XMODEM;
                 break;

src/xymodem.c

@@ -13,6 +13,7 @@
 #include <termios.h>
 #include <sys/stat.h>
 #include <sys/mman.h>
+#include <poll.h>
 #include "xymodem.h"
 #include "print.h"
 #include "misc.h"
@@ -22,10 +23,20 @@
 #define ACK 0x06
 #define NAK 0x15
 #define CAN 0x18
-#define EOT "\004"
+#define EOT 0x04
+
+#define SOH_STR "\001"
+#define ACK_STR "\006"
+#define NAK_STR "\025"
+#define CAN_STR "\030"
+#define EOT_STR "\004"
 
 #define OK  0
 #define ERR (-1)
+#define ERR_FATAL (-2)
+#define USER_CAN  (-5)
+
+#define RX_IGNORE 5
 
 #define min(a, b)       ((a) < (b) ? (a) : (b))
 
@@ -161,7 +172,7 @@ static int xmodem_1k(int sio, const void *data, size_t len, int seq)
     while (seq) {
         if (key_hit)
             return ERR;
-        if (write(sio, EOT, 1) < 0) {
+        if (write(sio, EOT_STR, 1) < 0) {
             tio_error_print("Write EOT to serial failed");
             return ERR;
         }
@@ -280,7 +291,7 @@ static int xmodem(int sio, const void *data, size_t len)
     while (1) {
         if (key_hit)
             return ERR;
-        if (write(sio, EOT, 1) < 0) {
+        if (write(sio, EOT_STR, 1) < 0) {
             tio_error_print("Write EOT to serial failed");
             return ERR;
         }
@@ -301,6 +312,345 @@ static int xmodem(int sio, const void *data, size_t len)
     return 0; /* not reached */
 }
 
+int start_receive(int sio)
+{
+    int rc;
+    struct pollfd fds;
+    fds.events = POLLIN;
+    fds.fd = sio;
+    for (int n = 0; n < 20; n++)
+    {
+        /* Send the 'C' byte until the sender of the file responds with
+           something.  The start character will be sent once a second for a number of
+           seconds.  If nothing is received in that time then return false to indicate
+           that the transfer did not start. */
+        rc = write(sio, "C", 1);
+        if (rc < 0) {
+            if (errno ==  EWOULDBLOCK) {
+                usleep(1000);
+                continue;
+            }
+            tio_error_print("Write packet to serial failed");
+            return ERR;
+        }
+        /* Wait until data is available */
+        rc = poll(&fds, 1, 3000);
+        if (rc < 0)
+        {
+            tio_error_print("%s", strerror(errno));
+            return rc;
+        }
+        else if (rc > 0)
+        {
+            if (fds.revents & POLLIN)
+            {
+                return rc;
+            }
+        }
+        if (key_hit)
+            return USER_CAN;
+    }
+    return rc;
+}
+
+uint16_t update_CRC(uint16_t crc, char data_char) 
+{
+    uint8_t data = data_char;
+    crc = crc ^ ((uint16_t)data << 8);
+    for (int ix = 0; (ix < 8); ix++)
+    {
+        if (crc & 0x8000)
+        {
+            crc = (crc << 1) ^ 0x1021;
+        }
+        else
+        {
+            crc <<= 1;
+        }
+    }
+    return crc;
+}
+
+int receive_packet(int sio, struct xpacket packet, int fd)
+{
+    char rxSeq1, rxSeq2 = 0;
+    char resp = 0;
+    uint16_t calcCrc = 0;
+    uint16_t rxCrc = 0;
+    int rc;
+
+    struct pollfd fds;
+    fds.events = POLLIN;
+    fds.fd = sio;
+
+    /* Read seq bytes*/
+    rc = read_poll(sio, &rxSeq1, 1, 3000);
+    if (rc == 0) {
+        tio_error_print("Timeout waiting for first seq byte");
+        return ERR;
+    } else if (rc < 0) {
+        tio_error_print("Error reading first seq byte")
+        return ERR_FATAL;
+    }
+    rc = read_poll(sio, &rxSeq2, 1, 3000);
+    if (rc == 0) {
+        tio_error_print("Timeout waiting for second seq byte");
+        return ERR;
+    } else if (rc < 0) {
+        tio_error_print("Error reading second seq byte")
+        return ERR_FATAL;
+    }
+    if (key_hit)
+            return USER_CAN;
+
+    /* Read packet Data */
+    for (unsigned ix = 0; (ix < sizeof(packet.data)); ix++)
+    {
+        rc = read_poll(sio, &resp, 1, 3000);
+        /* If the read times out or fails then fail this packet. */ 
+        if (rc == 0)
+        {
+            tio_error_print("Timeout waiting for next packet char");
+            rc = write(sio, CAN_STR, 1);
+            if (rc < 0) {
+                tio_error_print("Write cancel packet to serial failed");
+                return ERR_FATAL;
+            }
+            return ERR;
+        } else if (rc < 0) {
+            tio_error_print("Error reading next packet char")
+            rc = write(sio, CAN_STR, 1);
+            if (rc < 0) {
+                tio_error_print("Write cancel packet to serial failed");
+            }
+            return ERR_FATAL;
+        }
+        packet.data[ix] = (uint8_t) resp;
+        calcCrc = update_CRC(calcCrc, resp);
+        if (key_hit)
+            return USER_CAN;
+    }
+
+    /* Read CRC */
+    rc = read_poll(sio, &resp, 1, 3000);
+    if (rc == 0) {
+        tio_error_print("Timeout waiting for first CRC byte");
+        return ERR;
+    } else if (rc < 0) {
+        tio_error_print("Error reading first CRC byte")
+        return ERR_FATAL;
+    }
+
+    uint8_t uresp = resp;
+    uint16_t uresp16 = uresp;
+    rxCrc  = uresp16 << 8;
+
+    rc = read_poll(sio, &resp, 1, 3000);
+    if (rc == 0) {
+        tio_error_print("Timeout waiting for second CRC byte");
+        return ERR;
+    } else if (rc < 0) {
+        tio_error_print("Error reading second CRC byte")
+        return ERR_FATAL;
+    }
+    
+    uresp = resp;
+    uresp16 = uresp;
+    rxCrc |= uresp16;
+
+    if (key_hit)
+            return USER_CAN;
+
+    /* At this point in the code, there should not be anything in the receive buffer
+    because the sender has just sent a complete packet and is waiting on a response. */
+    rc = poll(&fds, 1, 10);
+    if (rc < 0)
+    {
+        tio_error_print("%s", strerror(errno));
+        tio_error_print("Poll check error after packet finish");
+        rc = write(sio, CAN_STR, 1);
+        if (rc < 0) {
+            tio_error_print("Write cancel packet to serial failed");
+        }
+        return ERR_FATAL;
+    }
+    else if (rc > 0)
+    {
+        if (fds.revents & POLLIN)
+        {
+            tio_error_print("RX sync error");
+            char dummy = 0;
+            /* Drain buffer */
+            while (read_poll(sio, &dummy, 1, 100) > 0) {}
+            return ERR;
+        }
+    }
+
+    uint8_t tester = 0xff;
+    uint8_t seq1 = rxSeq1;
+    uint8_t seq2 = rxSeq2;
+
+    if ((calcCrc == rxCrc) && (seq1 == packet.seq - 1) && ((seq1 ^ seq2) == tester))
+    {
+        /* Resend of previously processed packet. */
+        rc = write(sio, ACK_STR, 1);
+        if (rc < 0) {
+            tio_error_print("Write acknowlegdement packet to serial failed");
+            return ERR_FATAL;
+        }
+        return RX_IGNORE;
+    }
+    else if ((calcCrc != rxCrc) || (seq1 != packet.seq) || ((seq1 ^ seq2) != tester))
+    {
+        /* Fail if the CRC or sequence number is not correct or if the two received
+           sequence numbers are not the complement of one another. */
+        tio_error_print("Bad CRC or sequence number");
+        tio_debug_printf("CRC read: %u", rxCrc);
+        tio_debug_printf("CRC calculated: %u", calcCrc);
+        tio_debug_printf("Seq read: %hhu", rxSeq1);
+        tio_debug_printf("Seq should be: %hhu", packet.seq);
+        tio_debug_printf("inv seq: %hhu", rxSeq2);
+        return ERR;
+    }
+    else
+    {
+        /* The data is good.  Process the packet then ACK it to the sender. */
+        rc = write(fd, packet.data, sizeof(packet.data));
+        if (rc < 0)
+        {
+            tio_error_print("Problem writing to file");
+            rc = write(sio, CAN_STR, 1);
+            if (rc < 0) {
+                tio_error_print("Write cancel packet to serial failed");
+            }
+            return ERR_FATAL;
+        }
+        rc = write(sio, ACK_STR, 1);
+        if (rc < 0)
+        {
+            tio_error_print("Write acknowlegdement packet to serial failed");
+            return ERR_FATAL;
+        }
+    }
+
+    return OK;
+}
+
+int xmodem_receive(int sio, int fd)
+{
+    struct xpacket  packet;
+    char            resp = 0;
+    int             rc;
+    bool complete = false;
+    char status;
+
+    /* Drain pending characters from serial line.*/
+    while(1) {
+        if (key_hit)
+            return -1;
+        rc = read_poll(sio, &resp, 1, 50);
+        if (rc == 0) {
+            if (resp == CAN) return ERR;
+            break;
+        }
+        else if (rc < 0) {
+            if (rc != USER_CAN) {
+                tio_error_print("Read sync from serial failed");
+            }
+            return ERR;
+        }
+    }
+
+    /* Always work with 128b packets */
+    packet.seq  = 1;
+    packet.type = SOH;
+
+    /* Start Receive*/
+    rc = start_receive(sio);
+    if (rc == 0)
+    {
+        tio_error_print("Timeout waiting for transfer to start");
+        return ERR;
+    } else if (rc < 0) {
+        tio_error_print("Error starting XMODEM receive");
+        return ERR;
+    }
+
+    while (!complete) {
+        /* Poll for 1 new byte for 3 seconds */
+        rc = read_poll(sio, &resp, 1, 3000);
+        if (rc == 0) {
+            tio_error_print("Timeout waiting for start of next packet");
+            return ERR;
+        } else if (rc < 0) {
+            tio_error_print("Error reading start of next packet")
+            return ERR;
+        }
+        if (key_hit)
+            return USER_CAN;
+
+        switch(resp)
+        {
+            case SOH:
+            /* Start of a packet */
+            rc = receive_packet(sio, packet, fd);
+            if (rc == OK) {
+                packet.seq++;
+                status = '.';
+            } else if (rc == ERR) {
+                rc = write(sio, NAK_STR, 1);
+                if (rc < 0) {
+                    tio_error_print("Writing not acknowledge packet to serial failed");
+                    return ERR;
+                }
+                status = 'N';
+            } else if (rc == ERR_FATAL) {
+                tio_error_print("Receive cancelled due to fatal error");
+                return ERR;
+            } else if (rc == USER_CAN) {
+                rc = write(sio, CAN_STR, 1);
+                if (rc < 0) {
+                    tio_error_print("Writing cancel to serial failed");
+                    return ERR;
+                }
+                return USER_CAN;
+            } else if (rc == RX_IGNORE) {
+                status = ':';
+            }
+            break;
+
+            case EOT:
+            /* End of Transfer */
+            rc = write(sio, ACK_STR, 1);
+            if (rc < 0)
+            {
+                tio_error_print("Write acknowlegdement packet to serial failed");
+                return ERR;
+            }
+            complete = true;
+            status = '\0';
+            write(STDOUT_FILENO, "|\r\n", 3);
+            break;
+
+            case CAN:
+            /* Cancel from sender */
+            tio_error_print("Transmission cancelled from sender");
+            return ERR;
+            break;
+
+            default:
+            tio_error_print("Unexpected character received waiting for next packet");
+            return ERR;
+            break;
+        }
+        
+
+        /* Update "progress bar" */
+        write(STDOUT_FILENO, &status, 1);
+    }
+    return OK;
+}
+
 int xymodem_send(int sio, const char *filename, modem_mode_t mode)
 {
     size_t         len;
@@ -355,3 +705,35 @@ int xymodem_send(int sio, const char *filename, modem_mode_t mode)
     close(fd);
     return rc;
 }
+
+int xymodem_receive(int sio, const char *filename, modem_mode_t mode)
+{
+    int            rc, fd;
+
+    /* Create new file */
+    fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC);
+    if (fd < 0) {
+        tio_error_print("Could not open file");
+        return ERR;
+    }
+
+    /* Do transfer */
+    key_hit = 0;
+    if (mode == XMODEM_1K) {
+        tio_error_print("Not supported");
+        rc = -1;
+    }
+    else if (mode == XMODEM_CRC) {
+        rc = xmodem_receive(sio, fd);
+    }
+    else {
+        tio_error_print("Not supported");
+        rc = -1;
+    }
+    key_hit = 0xff;
+
+    /* Flush serial and release resources */
+    tcflush(sio, TCIOFLUSH);
+    close(fd);
+    return rc;
+}

src/xymodem.h

@@ -30,3 +30,5 @@ typedef enum {
 extern char key_hit;
 
 int xymodem_send(int sio, const char *filename, modem_mode_t mode);
+
+int xymodem_receive(int sio, const char *filename, modem_mode_t mode);