Improve address and connection handling

* improve address checking
+ add ipv6 capabilities

Change-Id: I5369336bec449c27d79d857018f319266dfd4d0e
Reviewed-on: https://forge.frm2.tum.de/review/c/secop/frappy/+/30885
Tested-by: Jenkins Automated Tests <pedersen+jenkins@frm2.tum.de>
Reviewed-by: Alexander Zaft <a.zaft@fz-juelich.de>

frappy/lib/__init__.py

@@ -21,9 +21,9 @@
 # *****************************************************************************
 """Define helpers"""
 
-import re
 import importlib
 import linecache
+import re
 import socket
 import sys
 import threading
@@ -295,50 +295,68 @@ def formatException(cut=0, exc_info=None, verbose=False):
     return ''.join(res)
 
 
-HOSTNAMEPAT = re.compile(r'[a-z0-9_.-]+$', re.IGNORECASE)  # roughly checking for a valid hostname or ip address
+HOSTNAMEPART = re.compile(r'^(?!-)[a-z0-9-]{1,63}(?<!-)$', re.IGNORECASE)
+
+def validate_hostname(host):
+    """checks if the rules for valid hostnames are adhered to"""
+    if len(host) > 255:
+        return False
+    for part in host.split('.'):
+        if not HOSTNAMEPART.match(part):
+            return False
+    return True
 
 
-def parseHostPort(host, defaultport):
-    """Parse host[:port] string and tuples
+def validate_ipv4(addr):
+    """check if v4 address is valid."""
+    try:
+        socket.inet_aton(addr)
+    except OSError:
+        return False
+    return True
 
-    Specify 'host[:port]' or a (host, port) tuple for the mandatory argument.
-    If the port specification is missing, the value of the defaultport is used.
 
-    raises TypeError in case host is neither a string nor an iterable
-    raises ValueError in other cases of invalid arguments
+def validate_ipv6(addr):
+    """check if v6 address is valid."""
+    try:
+        socket.inet_pton(socket.AF_INET6, addr)
+    except OSError:
+        return False
+    return True
+
+
+def parse_ipv6_host_and_port(addr, defaultport=10767):
+    """ Parses IPv6 addresses with optional port. See parse_host_port for valid formats"""
+    if ']' in addr:
+        host, port = addr.rsplit(':', 1)
+        return host[1:-1], int(port)
+    if '.' in addr:
+        host, port = addr.rsplit('.', 1)
+        return host, int(port)
+    return (host, defaultport)
+
+def parse_host_port(host, defaultport=10767):
+    """Parses hostnames and IP (4/6) addressses.
+
+    The accepted formats are:
+    - a standard hostname
+    - base IPv6 or 4 addresses
+    - 'hostname:port'
+    - IPv4 addresses in the form of 'IPv4:port'
+    - IPv6 addresses in the forms '[IPv6]:port' or 'IPv6.port'
     """
-    if isinstance(host, str):
-        host, sep, port = host.partition(':')
-        if sep:
-            port = int(port)
-        else:
-            port = defaultport
-    else:
-        host, port = host
-    if not HOSTNAMEPAT.match(host):
-        raise ValueError(f'illegal host name {host!r}')
-    if 0 < port < 65536:
-        return host, port
-    raise ValueError(f'illegal port number: {port!r}')
-
-
-def tcpSocket(host, defaultport, timeout=None):
-    """Helper for opening a TCP client socket to a remote server.
-
-    Specify 'host[:port]' or a (host, port) tuple for the mandatory argument.
-    If the port specification is missing, the value of the defaultport is used.
-    If timeout is set to a number, the timout of the connection is set to this
-    number, else the socket stays in blocking mode.
-    """
-    host, port = parseHostPort(host, defaultport)
-
-    # open socket and set options
-    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
-    if timeout:
-        s.settimeout(timeout)
-    # connect
-    s.connect((host, int(port)))
-    return s
+    colons = host.count(':')
+    if colons == 0: # hostname/ipv4 wihtout port
+        port = defaultport
+    elif colons == 1: # hostname or ipv4 with port
+        host, port = host.split(':')
+        port = int(port)
+    else: # ipv6
+        host, port = parse_ipv6_host_and_port(host, defaultport)
+    if (validate_ipv4(host) or validate_hostname(host) or validate_ipv6(host)) \
+        and 0 < port < 65536:
+        return (host, port)
+    raise ValueError(f'invalid host {host!r} or port {port}')
 
 
 # keep a reference to socket to avoid (interpreter) shut-down problems