Refactor patty_kiss_tnc_recv()
Refactor patty_kiss_tnc_recv() to be much more compact and correct; ensure the KISS command byte is absolutely required, and that consecutive frame end markers are handled without error
This commit is contained in:
XANTRONIX Development
XANTRONIX Industrial
parent
06fe62ed7b
commit
ede262397b
2 changed files with 111 additions and 175 deletions
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@ -35,20 +35,15 @@ int patty_kiss_tnc_fd_unix(patty_kiss_tnc *tnc);
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void patty_kiss_tnc_close(patty_kiss_tnc *tnc);
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void patty_kiss_tnc_drop(patty_kiss_tnc *tnc);
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size_t patty_kiss_tnc_dropped(patty_kiss_tnc *tnc);
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void patty_kiss_tnc_flush(patty_kiss_tnc *tnc, size_t len);
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ssize_t patty_kiss_tnc_buffer(patty_kiss_tnc *tnc);
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ssize_t patty_kiss_tnc_decode(patty_kiss_tnc *tnc, void *frame, size_t *len, int *port);
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ssize_t patty_kiss_tnc_recv(patty_kiss_tnc *tnc,
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void **frame, int *port);
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void **frame,
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int *port);
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ssize_t patty_kiss_tnc_send(patty_kiss_tnc *tnc,
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const void *frame, size_t len, int port);
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const void *frame,
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size_t len,
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int port);
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#endif /* _PATTY_KISS_H */
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265
src/kiss.c
265
src/kiss.c
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@ -11,9 +11,10 @@
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#include <patty/kiss.h>
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enum kiss_flags {
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KISS_NONE = 0x00,
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KISS_FRAME = 0x01,
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KISS_ESCAPE = 0x02
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KISS_NONE = 0,
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KISS_FRAME = 1 << 0,
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KISS_COMMAND = 1 << 1,
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KISS_ESCAPE = 1 << 2
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};
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struct _patty_kiss_tnc {
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@ -21,8 +22,8 @@ struct _patty_kiss_tnc {
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int fd;
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void *frame,
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*buf;
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void *buf,
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*frame;
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size_t bufsz,
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buflen,
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@ -79,132 +80,35 @@ void patty_kiss_tnc_close(patty_kiss_tnc *tnc) {
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free(tnc);
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}
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ssize_t patty_kiss_tnc_buffer(patty_kiss_tnc *tnc) {
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size_t fillsz = tnc->bufsz - tnc->buflen;
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ssize_t readlen = 0;
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static ssize_t tnc_buffer(patty_kiss_tnc *tnc) {
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ssize_t readlen;
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/*
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* If the buffer needs to be filled, then fill it.
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*/
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if (fillsz) {
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void *dest = ((uint8_t *)tnc->buf) + tnc->buflen;
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if (tnc->buflen == tnc->bufsz) {
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goto full;
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}
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if ((readlen = read(tnc->fd, dest, fillsz)) < 0) {
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errno = EIO;
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goto error_io;
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if ((readlen = read(tnc->fd, tnc->buf, tnc->bufsz - tnc->buflen)) < 0) {
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goto error_read;
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}
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tnc->buflen += readlen;
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}
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return readlen;
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error_io:
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return -1;
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}
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ssize_t patty_kiss_tnc_decode(patty_kiss_tnc *tnc, void *frame, size_t *len, int *port) {
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size_t i, b;
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enum kiss_flags flags = KISS_NONE;
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/*
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* The default port is always zero, unless a command byte issued from the
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* TNC in the first byte of the frame body.
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*/
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*port = 0;
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/*
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* Ah, yes, the icky state machine wherein we unescape things off the wire
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* and whatnot.
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*/
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for (i=0, b=0; i<tnc->buflen; i++) {
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uint8_t c = ((uint8_t *)tnc->buf)[i];
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if (i == 0) {
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if (c != PATTY_KISS_FEND) {
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/*
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* If the first byte is not a frame end, then that's a bad thing.
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*/
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errno = EIO;
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goto error_io;
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}
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} else if (i == 1) {
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if (PATTY_KISS_COMMAND(c) != PATTY_KISS_DATA) {
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errno = EIO;
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goto error_io;
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}
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*port = PATTY_KISS_COMMAND_PORT(c);
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continue;
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}
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if ((flags & KISS_FRAME) == 0) {
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if (c == PATTY_KISS_FEND) {
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flags |= KISS_FRAME;
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continue;
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}
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errno = EIO;
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goto error_io;
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}
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if (flags & KISS_ESCAPE) {
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if (c == PATTY_KISS_TFEND) {
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((uint8_t *)frame)[b++] = PATTY_KISS_FEND;
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} else if (c == PATTY_KISS_TFESC) {
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((uint8_t *)frame)[b++] = PATTY_KISS_FESC;
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} else {
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errno = EIO;
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goto error_io;
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}
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flags &= ~KISS_ESCAPE;
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continue;
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}
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if (flags & KISS_FRAME) {
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if (c == PATTY_KISS_FESC) {
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flags |= KISS_ESCAPE;
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continue;
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} else if (c == PATTY_KISS_FEND) {
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break;
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}
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((uint8_t *)frame)[b++] = c;
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}
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}
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/*
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* Return empty-handed if we do not have a fully book-ended frame.
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*/
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if ((flags & KISS_FRAME) == 0) {
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*len = 0;
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*port = 0;
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full:
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return 0;
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}
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*len = b;
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return i;
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error_io:
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error_read:
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return -1;
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}
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void patty_kiss_tnc_drop(patty_kiss_tnc *tnc) {
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memset(tnc->buf, '\0', tnc->bufsz);
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memset(tnc->frame, '\0', tnc->bufsz);
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static void tnc_flush(patty_kiss_tnc *tnc, size_t len) {
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memmove(tnc->buf, ((uint8_t *)tnc->buf) + len, tnc->buflen - len);
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tnc->buflen -= len;
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}
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static void tnc_drop(patty_kiss_tnc *tnc) {
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tnc->buflen = 0;
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tnc->dropped++;
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}
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@ -213,63 +117,97 @@ size_t patty_kiss_tnc_dropped(patty_kiss_tnc *tnc) {
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return tnc->dropped;
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}
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void patty_kiss_tnc_flush(patty_kiss_tnc *tnc, size_t len) {
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/*
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* Move everything from the buffer not processed up to this point, to the
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* beginning of the buffer.
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*/
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memmove(tnc->buf, ((uint8_t *)tnc->buf) + len, tnc->buflen - len);
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ssize_t patty_kiss_tnc_recv(patty_kiss_tnc *tnc,
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void **frame,
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int *port) {
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size_t i = 0,
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b = 0;
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/*
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* Then, decrement the buffer length by the number of bytes already
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* processed.
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*/
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tnc->buflen -= len;
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}
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enum kiss_flags flags = KISS_NONE;
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ssize_t patty_kiss_tnc_recv(patty_kiss_tnc *tnc, void **frame, int *port) {
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ssize_t buffered, decoded;
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size_t framelen;
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/*
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* Initialize the frame to be returned to the caller.
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*/
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memset(tnc->frame, '\0', tnc->bufsz);
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do {
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/*
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* Fill the buffer with something to parse.
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*/
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if ((buffered = patty_kiss_tnc_buffer(tnc)) < 0) {
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if (tnc_buffer(tnc) < 0) {
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goto error_io;
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}
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/*
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* Try to decode the TNC buffer into the frame.
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*/
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if ((decoded = patty_kiss_tnc_decode(tnc, tnc->frame, &framelen, port)) < 0) {
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patty_kiss_tnc_drop(tnc);
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while (i < tnc->buflen) {
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uint8_t c = ((uint8_t *)tnc->buf)[i++];
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if (!(flags & KISS_FRAME)) {
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if (c == PATTY_KISS_FEND) {
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flags |= KISS_FRAME;
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continue;
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} else {
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errno = EIO;
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goto error_io;
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}
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} else {
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if (c == PATTY_KISS_FEND) {
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if (b > 0) {
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flags &= ~KISS_FRAME;
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goto done;
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}
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continue;
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}
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}
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if (!(flags & KISS_COMMAND)) {
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if (PATTY_KISS_COMMAND(c) != PATTY_KISS_DATA) {
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errno = EIO;
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goto error_io;
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}
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/*
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* If we can no longer buffer nor decode any data, then drop the whole
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* frame.
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*/
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if (decoded == 0 && buffered == 0) {
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patty_kiss_tnc_drop(tnc);
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}
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} while (decoded == 0);
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*port = PATTY_KISS_COMMAND_PORT(c);
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/*
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* Flush the buffer up to the point of the next frame start.
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*/
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patty_kiss_tnc_flush(tnc, decoded);
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flags |= KISS_COMMAND;
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continue;
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}
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if (!(flags & KISS_ESCAPE)) {
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if (c == PATTY_KISS_FESC) {
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flags |= KISS_ESCAPE;
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continue;
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}
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} else {
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switch (c) {
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case PATTY_KISS_TFEND:
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((uint8_t *)tnc->frame)[b++] = PATTY_KISS_FEND;
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flags &= ~KISS_ESCAPE;
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continue;
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case PATTY_KISS_TFESC:
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((uint8_t *)tnc->frame)[b++] = PATTY_KISS_FESC;
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flags &= ~KISS_ESCAPE;
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continue;
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default:
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errno = EIO;
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goto error_io;
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}
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}
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((uint8_t *)tnc->frame)[b++] = c;
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}
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done:
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if (flags & KISS_FRAME) {
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tnc_drop(tnc);
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*frame = NULL;
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} else {
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tnc_flush(tnc, i);
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*frame = tnc->frame;
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}
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return framelen;
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return (ssize_t)b;
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error_io:
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return -1;
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@ -286,7 +224,10 @@ static inline ssize_t write_command(int fd, int command, int port) {
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static uint8_t escape_fend[2] = { PATTY_KISS_FESC, PATTY_KISS_TFEND };
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static uint8_t escape_fesc[2] = { PATTY_KISS_FESC, PATTY_KISS_TFESC };
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ssize_t patty_kiss_tnc_send(patty_kiss_tnc *tnc, const void *buf, size_t len, int port) {
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ssize_t patty_kiss_tnc_send(patty_kiss_tnc *tnc,
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const void *buf,
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size_t len,
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int port) {
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size_t i, start = 0, end = 0;
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if (write_byte(tnc->fd, PATTY_KISS_FEND) < 0) {
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