Initial commit

client/api.py

@@ -0,0 +1,52 @@
+import requests
+
+class APIError(Exception):
+    "A custom error we'll use when something goes wrong with the API"
+
+class SubRosaAPI:
+    """An API for the SubRosa server.
+    """
+
+    def __init__(self, url):
+        self.url = url
+
+    def get_user(self, username):
+        route = "/users"
+        params = {'name': username}
+        return self.get(route, params)
+
+    def create_user(self, username, public_key):
+        route = "/users/new"
+        params = {'name': username, 'public_key': public_key}
+        return self.post(route, params)
+
+    def get_messages(self, username):
+        route = "/messages"
+        params = {'name': username}
+        return self.get(route, params)
+
+    def send_message(self, sender, recipient, ciphertext, time_sent, time_sent_signature):
+        route = "/messages/send"
+        params = {
+            'sender': sender, 
+            'recipient': recipient,
+            'ciphertext': ciphertext,
+            'time_sent': time_sent,
+            'time_sent_signature': time_sent_signature,
+        }
+        return self.get(route, params)
+
+    def get(self, route, params):
+        response = requests.get(self.url + route, json=params)
+        if response.ok:
+            return response.json()
+        else:
+            raise APIError(response.json()['error'])
+
+    def post(self, route, params):
+        response = requests.post(self.url + route, json=params)
+        if response.ok:
+            return response.json()
+        else:
+            raise APIError(response.json()['error'])
+

client/user_interface.py

@@ -0,0 +1,106 @@
+from pathlib import Path
+from api import SubRosaAPI, APIError
+from datetime import datetime
+import sys
+sys.path.insert(0, ".")
+from encryption import PrivateKey, PublicKey
+
+class SubRosaUI:
+    """A user interface to the SubRosa chat system.
+    """
+    def __init__(self, private_key_file, url):
+        self.api = SubRosaAPI(url)
+        if Path(private_key_file).exists():
+            self.private_key = PrivateKey.load(private_key_file)
+        else:
+            self.private_key = PrivateKey.generate()
+            self.private_key.save(private_key_file)
+        self.public_key = self.private_key.get_public_key()
+
+    def run(self, username):
+        """Runs the client UI.
+        """
+        self.username = username
+        self.user = self.get_or_create_user(username)
+        print("Welcome to SubRosa.")
+        while True:
+            choice = self.choose_action_from_menu()
+            if choice == 'VIEW':
+                self.show_messages()
+            elif choice == 'SEND':
+                self.send_message()
+            print("=" * 80)
+
+    def get_or_create_user(self, username):
+        """Gets user info from the server, or creates the user. 
+        If the user already exists, checks that our public key matches
+        the server's public key for the user. 
+        """
+        try:
+            user = self.api.get_user(username)
+            if user['public_key'] != str(self.public_key):
+                raise ValueError(f"Invalid key for {username}")
+        except APIError:
+            user = self.api.create_user(username, str(self.public_key))
+        return user
+
+    def choose_action_from_menu(self):
+        """Gets a choice from the user. 
+        """
+        print("What would you like to do?")
+        print("1. See messages")
+        print("2. Send a message")
+        while True:
+            choice = input("> ").strip()
+            if choice == '1':
+                return 'VIEW'
+            elif choice == '2': 
+                return 'SEND'
+
+    def show_messages(self):
+        """Fetches all messages and displays them. 
+        Note: The messages arrive from the server encrypted.
+        """
+        messages = self.api.get_messages(self.username)['messages']
+        if messages:
+            for i, message in enumerate(messages):
+                print('-' * 80)
+                print(f"{i}. From {message['sender']}:")
+                print(message['ciphertext'])
+        else:
+            print(f"No messages for {self.username}.")
+
+    def send_message(self):
+        """Sends a message.
+        """
+        try:
+            recipient_name = input("Username of recipient: ").strip()
+            recipient = self.api.get_user(recipient_name)
+        except APIError:
+            print(f"No user named {recipient_name}.")
+            return
+        plaintext = input("Message: ")
+        print('-' * 80)
+        print(f"Sorry, couldn't send a message to {recipient_name}; this method isn't implemented yet.")
+
+    def get_current_time(self):
+        return datetime.utcnow().isoformat()
+
+def main():
+    from argparse import ArgumentParser
+    parser = ArgumentParser()
+    parser.add_argument("username", help="Existing or new username.")
+    parser.add_argument("-k", "--key", 
+        default="subrosa_private_key.pem", 
+        help="Private key file. Will be created if it does not exist."
+    )
+    parser.add_argument("-s", "--server-url", 
+        default="https://subrosa.makingwithcode.org",
+        help='Server URL. Use "http://127.0.0.1:8000" for a local server.'
+    )
+    args = parser.parse_args()
+    ui = SubRosaUI(args.key, args.server_url)
+    ui.run(args.username)
+
+if __name__ == '__main__':
+    main()