tests/multi_net: Add test coverage for socket recv flag MSG_PEEK.

Adds TCP and UDP multi_net test cases.

This work was funded through GitHub Sponsors.

Signed-off-by: Angus Gratton <angus@redyak.com.au>

tests/multi_net/tcp_recv_peek.py

@@ -0,0 +1,46 @@
+# Test TCP recv with MSG_PEEK
+#
+# Note that bare metal LWIP only returns at most one packet's worth of TCP data
+# in any recv() call - including when peeking - so can't be too clever with
+# different recv() combinations
+import socket
+import random
+
+
+# Server
+def instance0():
+    PORT = random.randrange(10000, 50000)
+    multitest.globals(IP=multitest.get_network_ip(), PORT=PORT)
+    s = socket.socket()
+    s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+    s.bind(socket.getaddrinfo("0.0.0.0", PORT)[0][-1])
+    s.listen()
+    multitest.next()
+    s2, _ = s.accept()
+    print(s2.recv(8, socket.MSG_PEEK))
+    print(s2.recv(8))
+    s2.send(b"1234567890")
+    multitest.broadcast("0-sent")
+    multitest.wait("1-sent")
+    print(s2.recv(5, socket.MSG_PEEK))
+    print(s2.recv(5, socket.MSG_PEEK))
+    multitest.broadcast("0-recved")
+    multitest.wait("1-recved")  # sync here necessary as MP sends RST if closing TCP early
+    s2.close()
+    s.close()
+
+
+# Client
+def instance1():
+    multitest.next()
+    s = socket.socket()
+    s.connect(socket.getaddrinfo(IP, PORT)[0][-1])
+    s.send(b"abcdefgh")
+    multitest.broadcast("1-sent")
+    multitest.wait("0-sent")
+    s.send(b"klmnopqr")
+    print(s.recv(5, socket.MSG_PEEK))
+    print(s.recv(10))
+    multitest.broadcast("1-recved")
+    multitest.wait("0-recved")
+    s.close()

tests/multi_net/udp_recv_peek.py

@@ -0,0 +1,36 @@
+# Test UDP recv and recvfrom with MSG_PEEK
+import random
+import socket
+import time
+
+
+# Server
+def instance0():
+    PORT = random.randrange(10000, 50000)
+    multitest.globals(IP=multitest.get_network_ip(), PORT=PORT)
+    s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+    s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+    s.bind(socket.getaddrinfo("0.0.0.0", PORT)[0][-1])
+    multitest.next()
+    peek_bytes, peek_addr = s.recvfrom(8, socket.MSG_PEEK)
+    print(peek_bytes)
+    real_bytes, real_addr = s.recvfrom(8)
+    print(real_bytes)
+    print(peek_addr == real_addr)  # source addr should be the same for each
+    res = s.sendto(b"1234567890", peek_addr)
+    print(res)
+    print(s.recv(5, socket.MSG_PEEK))
+    print(s.recv(5, socket.MSG_PEEK))
+    s.close()
+
+
+# Client
+def instance1():
+    multitest.next()
+    s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+    s.connect(socket.getaddrinfo(IP, PORT)[0][-1])
+    s.send(b"abcdefgh")
+    s.send(b"klmnopqr")
+    print(s.recv(5, socket.MSG_PEEK))
+    print(s.recv(10))
+    s.close()