mirror of
https://gitlab.isc.org/isc-projects/bind9
synced 2025-08-30 14:07:59 +00:00
Add various dig/host tests for TCP/UDP socket error handling cases
Rework the "ans8" server in the "digdelv" system test to support various modes of operations using a control channel. The supported modes are: 1. `silent` (do not respond) 2. `close` (UDP: same as `silent`; TCP: also close the connection) 3. `servfail` (always respond with `SERVFAIL`) 4. `unstable` (constantly switch between `silent` and `servfail`) Add multiple tests to check the handling of both TCP and UDP socket error scenarios in dig/host.
This commit is contained in:
Aram Sargsyan
@@ -20,7 +20,27 @@ import struct
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import dns, dns.message
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from dns.rcode import *
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def create_response(msg):
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modes = [
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b"silent", # Do not respond
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b"close", # UDP: same as silent; TCP: also close the connection
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b"servfail", # Always respond with SERVFAIL
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b"unstable", # Constantly switch between "silent" and "servfail"
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]
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mode = modes[0]
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n = 0
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def ctrl_channel(msg):
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global modes, mode, n
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msg = msg.splitlines().pop(0)
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print("Received control message: %s" % msg)
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if msg in modes:
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mode = msg
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n = 0
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print("New mode: %s" % str(mode))
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def create_servfail(msg):
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m = dns.message.from_wire(msg)
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qname = m.question[0].name.to_text()
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rrtype = m.question[0].rdtype
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@@ -45,6 +65,9 @@ ip4 = "10.53.0.8"
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try: port=int(os.environ["PORT"])
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except: port=5300
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try: ctrlport=int(os.environ['EXTRAPORT1'])
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except: ctrlport=5300
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query4_udp = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
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query4_udp.bind((ip4, port))
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@@ -53,6 +76,11 @@ query4_tcp.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
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query4_tcp.bind((ip4, port))
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query4_tcp.listen(100)
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ctrl4_tcp = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
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ctrl4_tcp.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
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ctrl4_tcp.bind((ip4, ctrlport))
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ctrl4_tcp.listen(100)
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signal.signal(signal.SIGTERM, sigterm)
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f = open("ans.pid", "w")
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@@ -63,12 +91,11 @@ f.close()
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running = True
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print ("Listening on %s port %d" % (ip4, port))
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print ("Listening on %s port %d" % (ip4, ctrlport))
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print ("Ctrl-c to quit")
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input = [query4_udp, query4_tcp]
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input = [query4_udp, query4_tcp, ctrl4_tcp]
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n_udp = 0
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n_tcp = 0
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hung_conns = []
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while running:
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@@ -83,54 +110,79 @@ while running:
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for s in inputready:
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if s == query4_udp:
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n = n + 1
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print("UDP query received on %s" % ip4, end=" ")
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n_udp = n_udp + 1
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msg = s.recvfrom(65535)
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# Do not response to every other query.
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if n_udp % 2 == 1:
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print("NO RESPONSE")
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if mode == b"silent" or mode == b"close" or (mode == b"unstable" and n % 2 == 1):
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# Do not respond.
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print("NO RESPONSE (%s)" % str(mode))
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continue
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rsp = create_response(msg[0])
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if rsp:
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print(dns.rcode.to_text(rsp.rcode()))
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s.sendto(rsp.to_wire(), msg[1])
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elif mode == b"servfail" or (mode == b"unstable" and n % 2 == 0):
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rsp = create_servfail(msg[0])
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if rsp:
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print(dns.rcode.to_text(rsp.rcode()))
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s.sendto(rsp.to_wire(), msg[1])
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else:
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print("NO RESPONSE (can not create a response)")
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else:
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print("NO RESPONSE")
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raise(Exception("unsupported mode: %s" % mode))
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elif s == query4_tcp:
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n = n + 1
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print("TCP query received on %s" % ip4, end=" ")
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n_tcp = n_tcp + 1
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conn = None
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try:
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conn, addr = s.accept()
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# Do not response to every other query, hang the connection.
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if n_tcp % 2 == 1:
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print("NO RESPONSE")
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if mode == b"silent" or (mode == b"unstable" and n % 2 == 1):
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conn, addr = s.accept()
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# Do not respond and hang the connection.
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print("NO RESPONSE (%s)" % str(mode))
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hung_conns.append(conn)
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conn = None
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continue
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else:
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elif mode == b"close":
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conn, addr = s.accept()
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# Do not respond and close the connection.
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print("NO RESPONSE (%s)" % str(mode))
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conn.close()
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continue
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elif mode == b"servfail" or (mode == b"unstable" and n % 2 == 0):
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conn, addr = s.accept()
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# get TCP message length
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msg = conn.recv(2)
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if len(msg) != 2:
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print("NO RESPONSE")
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print("NO RESPONSE (can not read the message length)")
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conn.close()
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continue
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length = struct.unpack('>H', msg[:2])[0]
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msg = conn.recv(length)
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if len(msg) != length:
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print("NO RESPONSE")
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print("NO RESPONSE (can not read the message)")
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conn.close()
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continue
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rsp = create_response(msg)
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rsp = create_servfail(msg)
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if rsp:
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print(dns.rcode.to_text(rsp.rcode()))
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wire = rsp.to_wire()
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conn.send(struct.pack('>H', len(wire)))
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conn.send(wire)
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else:
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print("NO RESPONSE")
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except:
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print("NO RESPONSE")
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print("NO RESPONSE (can not create a response)")
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else:
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raise(Exception("unsupported mode: %s" % mode))
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except socket.error as e:
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print("NO RESPONSE (error: %s)" % str(e))
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if conn:
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conn.close()
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elif s == ctrl4_tcp:
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print("Control channel connected")
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conn = None
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try:
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# Handle control channel input
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conn, addr = s.accept()
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msg = conn.recv(1024)
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if msg:
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ctrl_channel(msg)
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conn.close()
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except s.timeout:
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pass
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if conn:
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conn.close()
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@@ -1001,6 +1001,8 @@ if [ -x "$DIG" ] ; then
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# See [GL #3020] for more information
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n=$((n+1))
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echo_i "check that dig handles UDP timeout followed by a SERVFAIL correctly ($n)"
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# Ask ans8 to be in "unstable" mode (switching between "silent" and "servfail" modes)
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echo "unstable" | sendcmd 10.53.0.8
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ret=0
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dig_with_opts +timeout=1 +nofail @10.53.0.8 a.example > dig.out.test$n 2>&1 || ret=1
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grep "status: SERVFAIL" dig.out.test$n > /dev/null || ret=1
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@@ -1009,6 +1011,8 @@ if [ -x "$DIG" ] ; then
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n=$((n+1))
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echo_i "check that dig handles TCP timeout followed by a SERVFAIL correctly ($n)"
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# Ask ans8 to be in "unstable" mode (switching between "silent" and "servfail" modes)
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echo "unstable" | sendcmd 10.53.0.8
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ret=0
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dig_with_opts +timeout=1 +nofail +tcp @10.53.0.8 a.example > dig.out.test$n 2>&1 || ret=1
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grep "status: SERVFAIL" dig.out.test$n > /dev/null || ret=1
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@@ -1016,19 +1020,54 @@ if [ -x "$DIG" ] ; then
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status=$((status+ret))
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n=$((n+1))
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echo_i "check that dig tries the next server after a connection error ($n)"
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echo_i "check that dig tries the next server after a UDP socket read error ($n)"
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ret=0
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dig_with_opts -d @10.53.0.99 @10.53.0.3 a.example > dig.out.test$n 2>&1 || ret=1
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dig_with_opts @10.53.0.99 @10.53.0.3 a.example > dig.out.test$n 2>&1 || ret=1
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grep "status: NOERROR" dig.out.test$n > /dev/null || ret=1
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if [ $ret -ne 0 ]; then echo_i "failed"; fi
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status=$((status+ret))
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n=$((n+1))
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echo_i "check that dig tries the next server after timeouts ($n)"
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# Ask ans4 to not respond to queries
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echo "//" | sendcmd 10.53.0.4
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echo_i "check that dig tries the next server after a TCP socket read error ($n)"
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# Ask ans8 to be in "close" mode, which closes the connection after accepting it
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echo "close" | sendcmd 10.53.0.8
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ret=0
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dig_with_opts -d @10.53.0.4 @10.53.0.3 a.example > dig.out.test$n 2>&1 || ret=1
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dig_with_opts +tcp @10.53.0.8 @10.53.0.3 a.example > dig.out.test$n 2>&1 || ret=1
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grep "status: NOERROR" dig.out.test$n > /dev/null || ret=1
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if [ $ret -ne 0 ]; then echo_i "failed"; fi
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status=$((status+ret))
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# Note that we combine TCP socket "connection error" and "timeout" cases in
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# one, because it is not trivial to simulate the timeout case in a system test
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# in Linux without a firewall, but the code which handles error cases during
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# the connection establishment time does not differentiate between timeout and
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# other types of errors (unlike during reading), so this one check should be
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# sufficient for both cases.
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n=$((n+1))
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echo_i "check that dig tries the next server after a TCP socket connection error/timeout ($n)"
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ret=0
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dig_with_opts +tcp @10.53.0.99 @10.53.0.3 a.example > dig.out.test$n 2>&1 || ret=1
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test $(grep "connection refused\|timed out" dig.out.test$n | wc -l) -eq 3 || ret=1
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grep "status: NOERROR" dig.out.test$n > /dev/null || ret=1
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if [ $ret -ne 0 ]; then echo_i "failed"; fi
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status=$((status+ret))
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n=$((n+1))
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echo_i "check that dig tries the next server after UDP socket read timeouts ($n)"
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# Ask ans8 to be in "silent" mode
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echo "silent" | sendcmd 10.53.0.8
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ret=0
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dig_with_opts +timeout=1 @10.53.0.8 @10.53.0.3 a.example > dig.out.test$n 2>&1 || ret=1
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grep "status: NOERROR" dig.out.test$n > /dev/null || ret=1
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if [ $ret -ne 0 ]; then echo_i "failed"; fi
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status=$((status+ret))
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n=$((n+1))
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echo_i "check that dig tries the next server after TCP socket read timeouts ($n)"
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# Ask ans8 to be in "silent" mode
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echo "silent" | sendcmd 10.53.0.8
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ret=0
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dig_with_opts +timeout=1 +tcp @10.53.0.8 @10.53.0.3 a.example > dig.out.test$n 2>&1 || ret=1
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grep "status: NOERROR" dig.out.test$n > /dev/null || ret=1
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if [ $ret -ne 0 ]; then echo_i "failed"; fi
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status=$((status+ret))
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