• Matthias Goebl's avatar
    [ISDN]: i4l: Fix DLE handling for i4l-audio · 7fde4d77
    Matthias Goebl authored
    The DLE handling in i4l-audio seems to be broken.
    It produces spurious DLEs so asterisk 1.2.24 with chan_modem_i4l
    gets irritated, the error message is:
    "chan_modem_i4l.c:450 i4l_read: Value of escape is ^ (17)".
    -> There shouldn't be a DLE-^.
    If a spurious DLE-ETX occurs, the audio connection even dies.
    I use a "AVM Fritz!PCI" isdn card.
    I found two issues that only appear if ISDN_AUDIO_SKB_DLECOUNT(skb) > 0:
    - The loop in isdn_tty.c:isdn_tty_try_read() doesn't escape a DLE if it's
      the last character.
    - The loop in isdn_common.c:isdn_readbchan_tty() doesn't copy its characters,
      it only remembers the last one ("last = *p;").
      Compare it with the loop in isdn_common.c:isdn_readbchan(), that *does*
      copy them ("*cp++ = *p;") correctly.
      The special handling of the "last" character made it more difficult.
      I compared it to linux-2.4.19: There was no "last"-handling and both loops
      did escape and copy all characters correctly.
    Signed-off-by: default avatarMatthias Goebl <matthias.goebl@goebl.net>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
isdn_tty.c 94.7 KB