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[ruby/resolv] Add an explicit with_udp_and_tcp helper to test_dns.rb
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This helper tries to bind UDP and TCP sockets to the same port, by
retrying the bind if the randomly-assinged UDP port is already taken in
TCP. This fixes a flaky test.

[Bug #20403]

ruby/resolv@3d135f99d9
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@KJTsanaktsidis @matzbot
KJTsanaktsidis authored and matzbot committed Mar 31, 2024
1 parent e02a06f commit 80bda10
Showing 1 changed file with 188 additions and 146 deletions.
334 changes: 188 additions & 146 deletions test/resolv/test_dns.rb
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Expand Up @@ -64,6 +64,50 @@ def with_udp(host, port)
end
end

def with_udp_and_tcp(host, port)
if port == 0
# Automatic port; we might need to retry until we find a port which is free on both UDP _and_ TCP.
retries_remaining = 5
t = nil
u = nil
begin
begin
u = UDPSocket.new
u.bind(host, 0)
_, udp_port, _, _ = u.addr
t = TCPServer.new(host, udp_port)
t.listen(1)
rescue Errno::EADDRINUSE, Errno::EACCES
# ADDRINUSE is what should get thrown if we try and bind a port which is already bound on UNIXen,
# but windows can sometimes throw EACCESS.
# See: https://stackoverflow.com/questions/48478869/cannot-bind-to-some-ports-due-to-permission-denied
retries_remaining -= 1
if retries_remaining > 0
t&.close
t = nil
u&.close
u = nil
retry
end
raise
end

# If we get to this point, we have a valid t & u socket
yield u, t
ensure
t&.close
u&.close
end
else
# Explicitly specified port, don't retry the bind.
with_udp(host, port) do |u|
with_tcp(host, port) do |t|
yield u, t
end
end
end
end

# [ruby-core:65836]
def test_resolve_with_2_ndots
conf = Resolv::DNS::Config.new :nameserver => ['127.0.0.1'], :ndots => 2
Expand Down Expand Up @@ -176,156 +220,154 @@ def test_query_ipv4_address_truncated_tcp_fallback

num_records = 50

with_udp('127.0.0.1', 0) {|u|
with_udp_and_tcp('127.0.0.1', 0) {|u, t|
_, server_port, _, server_address = u.addr
with_tcp('127.0.0.1', server_port) {|t|
client_thread = Thread.new {
Resolv::DNS.open(:nameserver_port => [[server_address, server_port]]) {|dns|
dns.getresources("foo.example.org", Resolv::DNS::Resource::IN::A)
}
}
udp_server_thread = Thread.new {
msg, (_, client_port, _, client_address) = Timeout.timeout(5) {u.recvfrom(4096)}
id, word2, qdcount, ancount, nscount, arcount = msg.unpack("nnnnnn")
qr = (word2 & 0x8000) >> 15
opcode = (word2 & 0x7800) >> 11
aa = (word2 & 0x0400) >> 10
tc = (word2 & 0x0200) >> 9
rd = (word2 & 0x0100) >> 8
ra = (word2 & 0x0080) >> 7
z = (word2 & 0x0070) >> 4
rcode = word2 & 0x000f
rest = msg[12..-1]
assert_equal(0, qr) # 0:query 1:response
assert_equal(0, opcode) # 0:QUERY 1:IQUERY 2:STATUS
assert_equal(0, aa) # Authoritative Answer
assert_equal(0, tc) # TrunCation
assert_equal(1, rd) # Recursion Desired
assert_equal(0, ra) # Recursion Available
assert_equal(0, z) # Reserved for future use
assert_equal(0, rcode) # 0:No-error 1:Format-error 2:Server-failure 3:Name-Error 4:Not-Implemented 5:Refused
assert_equal(1, qdcount) # number of entries in the question section.
assert_equal(0, ancount) # number of entries in the answer section.
assert_equal(0, nscount) # number of entries in the authority records section.
assert_equal(0, arcount) # number of entries in the additional records section.
name = [3, "foo", 7, "example", 3, "org", 0].pack("Ca*Ca*Ca*C")
assert_operator(rest, :start_with?, name)
rest = rest[name.length..-1]
assert_equal(4, rest.length)
qtype, _ = rest.unpack("nn")
assert_equal(1, qtype) # A
assert_equal(1, qtype) # IN
id = id
qr = 1
opcode = opcode
aa = 0
tc = 1
rd = rd
ra = 1
z = 0
rcode = 0
qdcount = 0
ancount = num_records
nscount = 0
arcount = 0
word2 = (qr << 15) |
(opcode << 11) |
(aa << 10) |
(tc << 9) |
(rd << 8) |
(ra << 7) |
(z << 4) |
rcode
msg = [id, word2, qdcount, ancount, nscount, arcount].pack("nnnnnn")
type = 1
klass = 1
ttl = 3600
rdlength = 4
num_records.times do |i|
rdata = [192,0,2,i].pack("CCCC") # 192.0.2.x (TEST-NET address) RFC 3330
rr = [name, type, klass, ttl, rdlength, rdata].pack("a*nnNna*")
msg << rr
end
u.send(msg[0...512], 0, client_address, client_port)
}
tcp_server_thread = Thread.new {
ct = t.accept
msg = ct.recv(512)
msg.slice!(0..1) # Size (only for TCP)
id, word2, qdcount, ancount, nscount, arcount = msg.unpack("nnnnnn")
qr = (word2 & 0x8000) >> 15
opcode = (word2 & 0x7800) >> 11
aa = (word2 & 0x0400) >> 10
tc = (word2 & 0x0200) >> 9
rd = (word2 & 0x0100) >> 8
ra = (word2 & 0x0080) >> 7
z = (word2 & 0x0070) >> 4
rcode = word2 & 0x000f
rest = msg[12..-1]
assert_equal(0, qr) # 0:query 1:response
assert_equal(0, opcode) # 0:QUERY 1:IQUERY 2:STATUS
assert_equal(0, aa) # Authoritative Answer
assert_equal(0, tc) # TrunCation
assert_equal(1, rd) # Recursion Desired
assert_equal(0, ra) # Recursion Available
assert_equal(0, z) # Reserved for future use
assert_equal(0, rcode) # 0:No-error 1:Format-error 2:Server-failure 3:Name-Error 4:Not-Implemented 5:Refused
assert_equal(1, qdcount) # number of entries in the question section.
assert_equal(0, ancount) # number of entries in the answer section.
assert_equal(0, nscount) # number of entries in the authority records section.
assert_equal(0, arcount) # number of entries in the additional records section.
name = [3, "foo", 7, "example", 3, "org", 0].pack("Ca*Ca*Ca*C")
assert_operator(rest, :start_with?, name)
rest = rest[name.length..-1]
assert_equal(4, rest.length)
qtype, _ = rest.unpack("nn")
assert_equal(1, qtype) # A
assert_equal(1, qtype) # IN
id = id
qr = 1
opcode = opcode
aa = 0
tc = 0
rd = rd
ra = 1
z = 0
rcode = 0
qdcount = 0
ancount = num_records
nscount = 0
arcount = 0
word2 = (qr << 15) |
(opcode << 11) |
(aa << 10) |
(tc << 9) |
(rd << 8) |
(ra << 7) |
(z << 4) |
rcode
msg = [id, word2, qdcount, ancount, nscount, arcount].pack("nnnnnn")
type = 1
klass = 1
ttl = 3600
rdlength = 4
num_records.times do |i|
rdata = [192,0,2,i].pack("CCCC") # 192.0.2.x (TEST-NET address) RFC 3330
rr = [name, type, klass, ttl, rdlength, rdata].pack("a*nnNna*")
msg << rr
end
msg = "#{[msg.bytesize].pack("n")}#{msg}" # Prefix with size
ct.send(msg, 0)
ct.close
client_thread = Thread.new {
Resolv::DNS.open(:nameserver_port => [[server_address, server_port]]) {|dns|
dns.getresources("foo.example.org", Resolv::DNS::Resource::IN::A)
}
result, _ = assert_join_threads([client_thread, udp_server_thread, tcp_server_thread])
assert_instance_of(Array, result)
assert_equal(50, result.length)
result.each_with_index do |rr, i|
assert_instance_of(Resolv::DNS::Resource::IN::A, rr)
assert_instance_of(Resolv::IPv4, rr.address)
assert_equal("192.0.2.#{i}", rr.address.to_s)
assert_equal(3600, rr.ttl)
}
udp_server_thread = Thread.new {
msg, (_, client_port, _, client_address) = Timeout.timeout(5) {u.recvfrom(4096)}
id, word2, qdcount, ancount, nscount, arcount = msg.unpack("nnnnnn")
qr = (word2 & 0x8000) >> 15
opcode = (word2 & 0x7800) >> 11
aa = (word2 & 0x0400) >> 10
tc = (word2 & 0x0200) >> 9
rd = (word2 & 0x0100) >> 8
ra = (word2 & 0x0080) >> 7
z = (word2 & 0x0070) >> 4
rcode = word2 & 0x000f
rest = msg[12..-1]
assert_equal(0, qr) # 0:query 1:response
assert_equal(0, opcode) # 0:QUERY 1:IQUERY 2:STATUS
assert_equal(0, aa) # Authoritative Answer
assert_equal(0, tc) # TrunCation
assert_equal(1, rd) # Recursion Desired
assert_equal(0, ra) # Recursion Available
assert_equal(0, z) # Reserved for future use
assert_equal(0, rcode) # 0:No-error 1:Format-error 2:Server-failure 3:Name-Error 4:Not-Implemented 5:Refused
assert_equal(1, qdcount) # number of entries in the question section.
assert_equal(0, ancount) # number of entries in the answer section.
assert_equal(0, nscount) # number of entries in the authority records section.
assert_equal(0, arcount) # number of entries in the additional records section.
name = [3, "foo", 7, "example", 3, "org", 0].pack("Ca*Ca*Ca*C")
assert_operator(rest, :start_with?, name)
rest = rest[name.length..-1]
assert_equal(4, rest.length)
qtype, _ = rest.unpack("nn")
assert_equal(1, qtype) # A
assert_equal(1, qtype) # IN
id = id
qr = 1
opcode = opcode
aa = 0
tc = 1
rd = rd
ra = 1
z = 0
rcode = 0
qdcount = 0
ancount = num_records
nscount = 0
arcount = 0
word2 = (qr << 15) |
(opcode << 11) |
(aa << 10) |
(tc << 9) |
(rd << 8) |
(ra << 7) |
(z << 4) |
rcode
msg = [id, word2, qdcount, ancount, nscount, arcount].pack("nnnnnn")
type = 1
klass = 1
ttl = 3600
rdlength = 4
num_records.times do |i|
rdata = [192,0,2,i].pack("CCCC") # 192.0.2.x (TEST-NET address) RFC 3330
rr = [name, type, klass, ttl, rdlength, rdata].pack("a*nnNna*")
msg << rr
end
u.send(msg[0...512], 0, client_address, client_port)
}
tcp_server_thread = Thread.new {
ct = t.accept
msg = ct.recv(512)
msg.slice!(0..1) # Size (only for TCP)
id, word2, qdcount, ancount, nscount, arcount = msg.unpack("nnnnnn")
qr = (word2 & 0x8000) >> 15
opcode = (word2 & 0x7800) >> 11
aa = (word2 & 0x0400) >> 10
tc = (word2 & 0x0200) >> 9
rd = (word2 & 0x0100) >> 8
ra = (word2 & 0x0080) >> 7
z = (word2 & 0x0070) >> 4
rcode = word2 & 0x000f
rest = msg[12..-1]
assert_equal(0, qr) # 0:query 1:response
assert_equal(0, opcode) # 0:QUERY 1:IQUERY 2:STATUS
assert_equal(0, aa) # Authoritative Answer
assert_equal(0, tc) # TrunCation
assert_equal(1, rd) # Recursion Desired
assert_equal(0, ra) # Recursion Available
assert_equal(0, z) # Reserved for future use
assert_equal(0, rcode) # 0:No-error 1:Format-error 2:Server-failure 3:Name-Error 4:Not-Implemented 5:Refused
assert_equal(1, qdcount) # number of entries in the question section.
assert_equal(0, ancount) # number of entries in the answer section.
assert_equal(0, nscount) # number of entries in the authority records section.
assert_equal(0, arcount) # number of entries in the additional records section.
name = [3, "foo", 7, "example", 3, "org", 0].pack("Ca*Ca*Ca*C")
assert_operator(rest, :start_with?, name)
rest = rest[name.length..-1]
assert_equal(4, rest.length)
qtype, _ = rest.unpack("nn")
assert_equal(1, qtype) # A
assert_equal(1, qtype) # IN
id = id
qr = 1
opcode = opcode
aa = 0
tc = 0
rd = rd
ra = 1
z = 0
rcode = 0
qdcount = 0
ancount = num_records
nscount = 0
arcount = 0
word2 = (qr << 15) |
(opcode << 11) |
(aa << 10) |
(tc << 9) |
(rd << 8) |
(ra << 7) |
(z << 4) |
rcode
msg = [id, word2, qdcount, ancount, nscount, arcount].pack("nnnnnn")
type = 1
klass = 1
ttl = 3600
rdlength = 4
num_records.times do |i|
rdata = [192,0,2,i].pack("CCCC") # 192.0.2.x (TEST-NET address) RFC 3330
rr = [name, type, klass, ttl, rdlength, rdata].pack("a*nnNna*")
msg << rr
end
msg = "#{[msg.bytesize].pack("n")}#{msg}" # Prefix with size
ct.send(msg, 0)
ct.close
}
result, _ = assert_join_threads([client_thread, udp_server_thread, tcp_server_thread])
assert_instance_of(Array, result)
assert_equal(50, result.length)
result.each_with_index do |rr, i|
assert_instance_of(Resolv::DNS::Resource::IN::A, rr)
assert_instance_of(Resolv::IPv4, rr.address)
assert_equal("192.0.2.#{i}", rr.address.to_s)
assert_equal(3600, rr.ttl)
end
}
end

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