Commit inicial

2026-09-10 09:24:22 -06:00
parent 202164a0da
commit 6e11482d36
14 changed files with 1634 additions and 1 deletions
@@ -0,0 +1,60 @@
+"""Codec para UTF-7 modificado (RFC 3501), usado por IMAP para nombres de carpetas."""
+
+import base64
+
+_B64_CHARS = "-,ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+"
+
+
+def encode(name: str) -> bytes:
+    """Codifica un nombre de carpeta Unicode a UTF-7 modificado (IMAP)."""
+    res = []
+    buffer = []
+
+    def flush():
+        if not buffer:
+            return
+        raw = "".join(buffer).encode("utf-16-be")
+        b64 = base64.b64encode(raw).decode("ascii").rstrip("=")
+        b64 = b64.replace("/", ",")
+        res.append("&" + b64 + "-")
+        buffer.clear()
+
+    for ch in name:
+        code = ord(ch)
+        if ch == "&":
+            flush()
+            res.append("&-")
+        elif 0x20 <= code <= 0x7E:
+            flush()
+            res.append(ch)
+        else:
+            buffer.append(ch)
+    flush()
+    return "".join(res).encode("ascii")
+
+
+def decode(data: bytes) -> str:
+    """Decodifica un nombre de carpeta IMAP en UTF-7 modificado a texto Unicode."""
+    s = data.decode("ascii")
+    res = []
+    i = 0
+    n = len(s)
+    while i < n:
+        ch = s[i]
+        if ch == "&":
+            end = s.find("-", i + 1)
+            if end == -1:
+                end = n
+            segment = s[i + 1:end]
+            if segment == "":
+                res.append("&")
+            else:
+                segment = segment.replace(",", "/")
+                padding = "=" * (-len(segment) % 4)
+                raw = base64.b64decode(segment + padding)
+                res.append(raw.decode("utf-16-be"))
+            i = end + 1
+        else:
+            res.append(ch)
+            i += 1
+    return "".join(res)