Add echoserver.pyx and client.pyx demo

src/client.pyx

+from stdlib.string cimport Str
+from stdlib.socket cimport getaddrinfo, socket, AF_UNSPEC, SOCK_STREAM, AI_PASSIVE, MSG_WAITALL, SHUT_WR, SHUT_RD
+
+from libc.stdio cimport puts, printf
+
+
+def main():
+    cdef const char * arg
+    cdef Str recv
+
+    loop = True
+
+    while loop:
+        b = input("Message to send:\n").encode()
+        arg = b
+        with nogil:
+            a = getaddrinfo(NULL, Str("3490"), AF_UNSPEC, SOCK_STREAM, 0, AI_PASSIVE)[0]
+
+            s = socket(a.family, a.socktype, a.protocol)
+
+            s.connect(a.sockaddr)
+
+            msg = Str(arg)
+            s.sendall(msg)
+
+            s.shutdown(SHUT_WR)
+
+            recv = s.recvall()
+            printf('received: %s\n\n', Str.to_c_str(recv))
+
+            s.close()
+
+            if msg != recv:
+                puts('sent and received are different')
+
+            if msg == Str('quit'):
+                loop = False
+
+main()

src/echoserver.pyx

+from stdlib.string cimport Str
+from stdlib.socket cimport getaddrinfo, socket, AF_UNSPEC, SOCK_STREAM, AI_PASSIVE, SHUT_RD, SHUT_WR
+
+from libc.stdio cimport puts, printf
+
+
+def main():
+    cdef Str recv
+    with nogil:
+        a = getaddrinfo(NULL, Str("3490"), AF_UNSPEC, SOCK_STREAM, 0, AI_PASSIVE)[0]
+
+        s = socket(a.family, a.socktype, a.protocol)
+
+        s.bind(a.sockaddr)
+
+        s.listen(5)
+
+        loop = True
+
+        while loop:
+            s1 = s.accept()
+
+            recv = s1.recvall()
+            printf('received: %s\n\n', Str.to_c_str(recv))
+
+            if recv == Str('quit'):
+                loop = False
+
+            s1.shutdown(SHUT_RD)
+
+            s1.sendall(recv)
+
+            s1.shutdown(SHUT_WR)
+
+            s1.close()
+
+        s.close()
+
+
+main()

src/stdlib/_socket.pxd

@@ -105,6 +105,13 @@ cdef extern from "<netinet/in.h>" nogil:
     enum: INET6_ADDRSTRLEN
 
 
+    unsigned long htonl(unsigned long hostlong)
+    unsigned short htons(unsigned short hostshort)
+    unsigned long ntohl(unsigned long netlong)
+    unsigned short ntohs(unsigned short netshort)
+
+
+
 cdef extern from "<arpa/inet.h>" nogil:
 
     const char  *inet_ntop(int af, const void *src, char *dst, socklen_t size)