SSH to a Cisco Switch - Processing "More" Responses

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Demonstrates connecting to a Cisco switch, entering privileged mode with the ena command, and running a command whose response is paged. Each page ends with --More-- and requires a SPACE character to request the next page.

Note: QuickShell allocates a PTY, which is what a network device console expects. The device presents an interactive prompt, and each command's output is read up to the next prompt.

load ./chilkat.dll

set success 0

#  This example requires the Chilkat API to have been previously unlocked.
#  See Global Unlock Sample for sample code.

#  Demonstrates connecting to a Cisco switch, entering privileged mode, and running a command
#  whose response is paged -- each page ends with "--More--" and requires a SPACE character to
#  request the next page.

set ssh [new_CkSsh]

set port 22
set success [CkSsh_Connect $ssh "172.16.16.100" $port]
if {$success == 0} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkSsh $ssh
    exit
}

#  Normally you would not hard-code the password in source.  You should instead obtain it
#  from an interactive prompt, environment variable, or a secrets vault.
set password "mySshPassword"

set success [CkSsh_AuthenticatePw $ssh "mySshLogin" $password]
if {$success == 0} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkSsh $ssh
    exit
}

set channelNum [CkSsh_QuickShell $ssh]
if {$channelNum < 0} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkSsh $ssh
    exit
}

#  IMPORTANT: Set a read timeout before receiving until a match.  ReadTimeoutMs defaults to 0,
#  which means no limit -- without it, this call waits forever if the received data never
#  contains a match.
CkSsh_put_ReadTimeoutMs $ssh 15000

set caseSensitive 1

#  In unprivileged mode the switch prompt ends with ">".
set success [CkSsh_ChannelReceiveUntilMatch $ssh $channelNum ">" "utf-8" $caseSensitive]
if {$success == 0} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkSsh $ssh
    exit
}

set received [CkSsh_getReceivedText $ssh $channelNum "utf-8"]
if {[CkSsh_get_LastMethodSuccess $ssh] == 0} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkSsh $ssh
    exit
}

puts "$received"

#  Send "ena" to enter privileged mode.  Cisco devices expect a bare CR to terminate a command.
set success [CkSsh_ChannelSendString $ssh $channelNum "ena\r" "utf-8"]
if {$success == 0} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkSsh $ssh
    exit
}

set success [CkSsh_ChannelReceiveUntilMatch $ssh $channelNum "Password:" "utf-8" $caseSensitive]
if {$success == 0} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkSsh $ssh
    exit
}

set received [CkSsh_getReceivedText $ssh $channelNum "utf-8"]
if {[CkSsh_get_LastMethodSuccess $ssh] == 0} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkSsh $ssh
    exit
}

puts "$received"

#  The enable password is separate from the login password, and likewise should come from a
#  secure source rather than being hard-coded.
set enablePassword "myEnablePassword"
set success [CkSsh_ChannelSendString $ssh $channelNum $enablePassword "utf-8"]
if {$success == 0} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkSsh $ssh
    exit
}

set success [CkSsh_ChannelSendString $ssh $channelNum "\r" "utf-8"]
if {$success == 0} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkSsh $ssh
    exit
}

#  In privileged mode the prompt ends with "#" instead of ">".
set success [CkSsh_ChannelReceiveUntilMatch $ssh $channelNum "#" "utf-8" $caseSensitive]
if {$success == 0} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkSsh $ssh
    exit
}

set received [CkSsh_getReceivedText $ssh $channelNum "utf-8"]
if {[CkSsh_get_LastMethodSuccess $ssh] == 0} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkSsh $ssh
    exit
}

puts "$received"

#  Run a command whose output is delivered a page at a time.
set success [CkSsh_ChannelSendString $ssh $channelNum "show running-config\r" "utf-8"]
if {$success == 0} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkSsh $ssh
    exit
}

#  Each read ends either at the device prompt (output complete) or at "--More--" (another page
#  is waiting).  Match the full prompt rather than a bare "#", because "#" also appears inside
#  configuration text and would match too early.
set saMatch [new_CkStringArray]

CkStringArray_Append $saMatch "MySwitchName#"
CkStringArray_Append $saMatch "--More--"

set sbReceived [new_CkStringBuilder]

set moreComing 1

while {$moreComing} {
    set success [CkSsh_ChannelReceiveUntilMatchN $ssh $channelNum $saMatch "utf-8" $caseSensitive]
    if {$success == 0} then {
        puts [CkSsh_lastErrorText $ssh]
        delete_CkSsh $ssh
        delete_CkStringArray $saMatch
        delete_CkStringBuilder $sbReceived
        exit
    }

    CkStringBuilder_Clear $sbReceived
    set pageText [CkSsh_getReceivedText $ssh $channelNum "utf-8"]
    if {[CkSsh_get_LastMethodSuccess $ssh] == 0} then {
        puts [CkSsh_lastErrorText $ssh]
        delete_CkSsh $ssh
        delete_CkStringArray $saMatch
        delete_CkStringBuilder $sbReceived
        exit
    }

    CkStringBuilder_Append $sbReceived $pageText
    puts "$pageText"

    #  If this page ended with "--More--", send a SPACE to request the next page.
    set moreComing [CkStringBuilder_Contains $sbReceived "--More--" $caseSensitive]
    if {$moreComing} then {
        set success [CkSsh_ChannelSendString $ssh $channelNum " " "utf-8"]
        if {$success == 0} then {
            puts [CkSsh_lastErrorText $ssh]
            delete_CkSsh $ssh
            delete_CkStringArray $saMatch
            delete_CkStringBuilder $sbReceived
            exit
        }

    }

}

CkSsh_Disconnect $ssh

delete_CkSsh $ssh
delete_CkStringArray $saMatch
delete_CkStringBuilder $sbReceived