A simple example of a HTTP client. Addresses #872

examples/simple-http-example.py

@@ -0,0 +1,67 @@
+#!/usr/bin/env python3
+
+"""A simple Python program to show the use of the pyOpenSSL
+library. We connect to a HTTPS server and retrieve its home page. (Of
+course, for this specific task, pyCurl would be a better solution but
+the goal is to demonstrate pyOpenSSL.)"""
+
+PORT = 443 # Hardwired
+PATH = "/" # Hardwired
+
+# https://www.pyopenssl.org/
+# https://pyopenssl.readthedocs.io/
+import OpenSSL
+
+import socket
+import sys
+
+if len(sys.argv) != 2:
+    raise Exception("Usage: %s hostname" % sys.argv[0])
+host = sys.argv[1]
+
+addrinfo = socket.getaddrinfo(host, PORT, 0)
+
+# We should loop over the IP addresses instead of taking only the first one…
+sock = socket.socket(addrinfo[0][0], socket.SOCK_STREAM)
+addr = addrinfo[0][4]
+print("Connecting to %s ..." % str(addr))
+
+context = OpenSSL.SSL.Context(OpenSSL.SSL.TLSv1_2_METHOD)
+
+# Use the OS' default CAs
+context.set_default_verify_paths()
+
+# Ask for a certificate check. Warning, this does not check the host
+# name, just the path from the CA, the expiration, may be the CRLs…
+context.set_verify(OpenSSL.SSL.VERIFY_PEER | OpenSSL.SSL.VERIFY_FAIL_IF_NO_PEER_CERT | \
+                   OpenSSL.SSL.VERIFY_CLIENT_ONCE,
+                   lambda conn, cert, errno, depth, preverify_ok: preverify_ok)
+
+session = OpenSSL.SSL.Connection(context, sock)
+session.set_tlsext_host_name(host.encode()) # Server Name Indication (SNI)
+
+# TCP
+session.connect((addr))
+
+# TLS
+session.do_handshake()
+cert = session.get_peer_certificate()
+print("Connected, its certificate is for \"%s\", delivered by \"%s\"" % \
+      (cert.get_subject().commonName,
+       cert.get_issuer().commonName))
+
+# HTTP
+request = """GET %s HTTP/1.1
+Host: %s
+Connection: close
+
+"""  % (PATH, host)
+session.write(request.replace("\n","\r\n"))
+
+# A real program must loop to read all the data
+data = session.read(4096)
+print("Got %i bytes, the first ones are: \"%s...\"" % (len(data),
+                                                       data[:256].decode()))
+
+session.close()
+sock.close()