Connect line implementation (and show line output change) (sonic-net#295)

Author: cawand

connect/main.py

@@ -3,6 +3,7 @@
 import click
 import errno
 import os
+import pexpect
 import subprocess
 import sys
 from click_default_group import DefaultGroup
@@ -85,18 +86,8 @@ def run_command(command, display_cmd=False):
     if display_cmd:
         click.echo(click.style("Command: ", fg='cyan') + click.style(command, fg='green'))
 
-    proc = subprocess.Popen(command, shell=True, stdout=subprocess.PIPE)
-
-    while True:
-        output = proc.stdout.readline()
-        if output == "" and proc.poll() is not None:
-            break
-        elif output:
-            click.echo(output.rstrip('\n'))
-
-    rc = proc.poll()
-    if rc != 0:
-        sys.exit(rc)
+    proc = pexpect.spawn(command)
+    proc.interact()
 
 CONTEXT_SETTINGS = dict(help_option_names=['-h', '--help', '-?'])
 
@@ -116,9 +107,19 @@ def connect():
 @connect.command('line')
 @click.argument('linenum')
 def line(linenum):
-    """Connect to line via serial connection"""
-    # TODO: Stub
-    return
+    """Connect to line LINENUM via serial connection"""
+    cmd = "consutil connect " + linenum
+    run_command(cmd)
+
+#
+# 'device' command ("connect device")
+#
+@connect.command('device')
+@click.argument('devicename')
+def device(devicename):
+    """Connect to device DEVICENAME via serial connection"""
+    cmd = "consutil connect -d " + devicename
+    run_command(cmd)
 
 if __name__ == '__main__':
     connect()

consutil/lib.py

@@ -8,6 +8,7 @@
 try:
     import click
     import re
+    import swsssdk
     import subprocess
     import sys
 except ImportError as e: 
@@ -18,6 +19,22 @@
 ERR_CMD = 1
 ERR_DEV = 2
 
+CONSOLE_PORT_TABLE = "CONSOLE_PORT"
+BAUD_KEY = "baud_rate"
+DEVICE_KEY = "remote_device"
+FLOW_KEY = "flow_control"
+DEFAULT_BAUD = "9600"
+
+# QUIET == True => picocom will not output any messages, and pexpect will wait for console
+#                  switch login or command line to let user interact with shell
+#        Downside: if console switch output ever does not match DEV_READY_MSG, program will think connection failed
+# QUIET == False => picocom will output messages - welcome message is caught by pexpect, so successful
+#                   connection will always lead to user interacting with shell
+#         Downside: at end of session, picocom will print exit message, exposing picocom to user
+QUIET = False
+DEV_READY_MSG = r"([Ll]ogin:|[Pp]assword:|[$>#])" # login prompt or command line prompt
+TIMEOUT_SEC = 0.2
+
 # runs command, exit if stderr is written to, returns stdout otherwise
 # input: cmd (str), output: output of cmd (str)
 def run_command(cmd):
@@ -57,8 +74,8 @@ def getBusyDevices():
 
     # matches any number of spaces then any number of digits
     regexPid = r" *(\d+)"
-    # matches anything of form: Xxx Xxx 00 00:00:00 0000
-    regexDate = r"([A-Z][a-z]{2} [A-Z][a-z]{2} \d{2} \d{2}:\d{2}:\d{2} \d{4})"
+    # matches anything of form: Xxx Xxx ( 0)or(00) 00:00:00 0000
+    regexDate = r"([A-Z][a-z]{2} [A-Z][a-z]{2} [\d ]\d \d{2}:\d{2}:\d{2} \d{4})"
     # matches any non-whitespace characters ending in minicom or picocom, 
     # then a space and any chars followed by /dev/ttyUSB<any digits>, 
     # then a space and any chars
@@ -75,16 +92,41 @@ def getBusyDevices():
             busyDevices[linenum_key] = (pid, date)
     return busyDevices
 
-# returns baud rate of device corresponding to line number
-# input: linenum (str)
-def getBaud(linenum):
-    checkDevice(linenum)
-    cmd = "sudo stty -F " + DEVICE_PREFIX + str(linenum)
-    output = run_command(cmd)
+# returns actual baud rate, configured baud rate,
+# and flow control settings of device corresponding to line number
+# input: linenum (str), output: (actual baud (str), configured baud (str), flow control (bool))
+def getConnectionInfo(linenum):
+    config_db = ConfigDBConnector()
+    config_db.connect()
+    entry = config_db.get_entry(CONSOLE_PORT_TABLE, str(linenum)) 
+    
+    conf_baud = "-" if BAUD_KEY not in entry else entry[BAUD_KEY]
+    act_baud = DEFAULT_BAUD if conf_baud == "-" else conf_baud
+    flow_control = False
+    if FLOW_KEY in entry and entry[FLOW_KEY] == "1":
+        flow_control = True
+
+    return (act_baud, conf_baud, flow_control)
+
+# returns the line number corresponding to target, or exits if line number cannot be found
+# if deviceBool, interprets target as device name
+# otherwise interprets target as line number
+# input: target (str), deviceBool (bool), output: linenum (str)
+def getLineNumber(target, deviceBool):
+    if not deviceBool:
+        return target
+
+    config_db = ConfigDBConnector()
+    config_db.connect()
 
-    match = re.match(r"^speed (\d+) baud;", output)
-    if match != None:
-        return match.group(1)
-    else:
-        click.echo("Unable to determine baud rate")
-        return ""
+    devices = getAllDevices()
+    linenums = list(map(lambda dev: dev[len(DEVICE_PREFIX):], devices))
+
+    for linenum in linenums:
+        entry = config_db.get_entry(CONSOLE_PORT_TABLE, linenum)
+        if DEVICE_KEY in entry and entry[DEVICE_KEY] == target:
+            return linenum
+
+    click.echo("Device {} does not exist".format(target))
+    sys.exit(ERR_DEV)
+    return ""

consutil/main.py

@@ -7,6 +7,8 @@
 
 try:
     import click
+    import os
+    import pexpect
     import re
     import subprocess
     from tabulate import tabulate
@@ -15,7 +17,7 @@
 
 @click.group()
 def consutil():
-    """consutil - Command-line utility for interacting with switchs via console device"""
+    """consutil - Command-line utility for interacting with switches via console device"""
 
     if os.geteuid() != 0:
         print "Root privileges are required for this operation"
@@ -28,7 +30,7 @@ def show():
     devices = getAllDevices()
     busyDevices = getBusyDevices()
 
-    header = ["Line", "Baud", "PID", "Start Time"]
+    header = ["Line", "Actual/Configured Baud", "PID", "Start Time"]
     body = []
     for device in devices:
         lineNum = device[11:]
@@ -38,10 +40,13 @@ def show():
         if lineNum in busyDevices:
             pid, date = busyDevices[lineNum]
             busy = "*"
-        baud = getBaud(lineNum)
+        actBaud, confBaud, _ = getConnectionInfo(lineNum)
+        # repeated "~" will be replaced by spaces - hacky way to align the "/"s
+        baud = "{}/{}{}".format(actBaud, confBaud, "~"*(15-len(confBaud)))
         body.append([busy+lineNum, baud, pid, date])
 
-    click.echo(tabulate(body, header, stralign="right"))
+    # replace repeated "~" with spaces - hacky way to align the "/"s
+    click.echo(tabulate(body, header, stralign="right").replace('~', ' ')) 
 
 # 'clear' subcommand
 @consutil.command()
@@ -62,10 +67,42 @@ def clear(linenum):
 
 # 'connect' subcommand
 @consutil.command()
-@click.argument('linenum')
-def connect(linenum):
-    """Connect to switch via console device"""
-    click.echo("connect linenum")
+@click.argument('target')
+@click.option('--devicename', '-d', is_flag=True, help="connect by name - if flag is set, interpret linenum as device name instead")
+def connect(target, devicename):
+    """Connect to switch via console device - TARGET is line number or device name of switch"""
+    lineNumber = getLineNumber(target, devicename)
+    checkDevice(lineNumber)
+    lineNumber = str(lineNumber)
+
+    # build and start picocom command
+    actBaud, _, flowBool = getConnectionInfo(lineNumber)
+    flowCmd = "h" if flowBool else "n"
+    quietCmd = "-q" if QUIET else ""
+    cmd = "sudo picocom -b {} -f {} {} {}{}".format(actBaud, flowCmd, quietCmd, DEVICE_PREFIX, lineNumber)
+    proc = pexpect.spawn(cmd)
+    proc.send("\n")
+
+    if QUIET:
+        readyMsg = DEV_READY_MSG
+    else:
+        readyMsg = "Terminal ready" # picocom ready message
+    busyMsg = "Resource temporarily unavailable" # picocom busy message
+
+    # interact with picocom or print error message, depending on pexpect output
+    index = proc.expect([readyMsg, busyMsg, pexpect.EOF, pexpect.TIMEOUT], timeout=TIMEOUT_SEC)
+    if index == 0: # terminal ready
+        click.echo("Successful connection to line {}\nPress ^A ^X to disconnect".format(lineNumber))
+        if QUIET:
+            # prints picocom output up to and including readyMsg
+            click.echo(proc.before + proc.match.group(0), nl=False) 
+        proc.interact()
+        if QUIET:
+            click.echo("\nTerminating...")
+    elif index == 1: # resource is busy
+        click.echo("Cannot connect: line {} is busy".format(lineNumber))
+    else: # process reached EOF or timed out
+        click.echo("Cannot connect: unable to open picocom process")
 
 if __name__ == '__main__':
     consutil()