add SSHPubKey ORM model

Includes `aurweb.models.ssh_pub_key.get_fingerprint(pubkey)` helper.

Signed-off-by: Kevin Morris <kevr@0cost.org>

aurweb/models/ssh_pub_key.py

@@ -0,0 +1,41 @@
+import os
+import tempfile
+
+from subprocess import PIPE, Popen
+
+from sqlalchemy.orm import backref, mapper, relationship
+
+from aurweb.models.user import User
+from aurweb.schema import SSHPubKeys
+
+
+class SSHPubKey:
+    def __init__(self, **kwargs):
+        self.UserID = kwargs.get("UserID")
+        self.Fingerprint = kwargs.get("Fingerprint")
+        self.PubKey = kwargs.get("PubKey")
+
+
+def get_fingerprint(pubkey):
+    with tempfile.TemporaryDirectory() as tmpdir:
+        pk = os.path.join(tmpdir, "ssh.pub")
+
+        with open(pk, "w") as f:
+            f.write(pubkey)
+
+        proc = Popen(["ssh-keygen", "-l", "-f", pk], stdout=PIPE, stderr=PIPE)
+        out, err = proc.communicate()
+
+        # Invalid SSH Public Key. Return None to the caller.
+        if proc.returncode != 0:
+            return None
+
+        parts = out.decode().split()
+        fp = parts[1].replace("SHA256:", "")
+
+    return fp
+
+
+mapper(SSHPubKey, SSHPubKeys, properties={
+    "User": relationship(User, backref=backref("ssh_pub_key", uselist=False))
+})