add .netrc support (#22)

Use the '--netrc' cmdline option or set the 'netrc' config option
to 'true' to enable the use of .netrc authentication data.

The 'machine' names for the .netrc info are the lowercase extractor
names (or categories): batoto, exhentai, nijie, pixiv, seiga.

docs/configuration.rst

@@ -23,6 +23,15 @@ Description Directory path used as the base for all download destinations.
 =========== =====
 
 
+netrc
+-----
+=========== =====
+Type        ``bool``
+Default     ``false``
+Description Enable the use of |.netrc|_ authentication data.
+=========== =====
+
+
 cache.file
 ----------
 =========== =====
@@ -331,7 +340,7 @@ Description The value of the ``limit`` parameter when loading
 
 
 extractor.reddit.morecomments
--------------------------
+-----------------------------
 =========== =====
 Type        ``bool``
 Default     ``false``
@@ -392,11 +401,13 @@ Description The ``refresh_token`` value you get from linking your Reddit account
 =========== =====
 
 
+.. |.netrc| replace:: ``.netrc``
 .. |tempfile.gettempdir()| replace:: ``tempfile.gettempdir()``
 .. |requests.get()| replace:: ``requests.get()``
 .. |mature_content| replace:: ``mature_content``
 .. |webbrowser.open()| replace:: ``webbrowser.open()``
 
+.. _.netrc:            https://stackoverflow.com/tags/.netrc/info
 .. _tempfile.gettempdir(): https://docs.python.org/3/library/tempfile.html#tempfile.gettempdir
 .. _requests.get():    https://docs.python-requests.org/en/latest/user/advanced/#timeouts
 .. _format string:     https://docs.python.org/3/library/string.html#formatstrings

docs/gallery-dl.conf

@@ -1,5 +1,6 @@
 {
     "base-directory": "/tmp/",
+    "netrc": false,
     "downloader":
     {
         "http":

gallery_dl/extractor/batoto.py

@@ -22,8 +22,7 @@ class BatotoExtractor():
 
     def login(self):
         """Login and set necessary cookies"""
-        username = self.config("username")
-        password = self.config("password")
+        username, password = self.auth_info()
         if username:
             cookies = self._login_impl(username, password)
             for key, value in cookies.items():

gallery_dl/extractor/common.py

@@ -10,6 +10,7 @@
 
 import os
 import time
+import netrc
 import queue
 import logging
 import requests
@@ -42,6 +43,24 @@ class Extractor():
         return config.interpolate(
             ("extractor", self.category, self.subcategory, key), default)
 
+    def auth_info(self):
+        """Return authentication information as (username, password) tuple"""
+        username = self.config("username")
+        password = None
+
+        if username:
+            password = self.config("password")
+        elif config.get(("netrc",), False):
+            try:
+                info = netrc.netrc().authenticators(self.category)
+                username, _, password = info
+            except (OSError, netrc.NetrcParseError) as exc:
+                self.log.error("netrc: %s", exc)
+            except TypeError:
+                self.log.warning("netrc: No authentication info")
+
+        return username, password
+
     def request(self, url, encoding=None, *args, **kwargs):
         response = safe_request(self.session, url, *args, **kwargs)
         if encoding:

gallery_dl/extractor/exhentai.py

@@ -182,13 +182,12 @@ class ExhentaiGalleryExtractor(Extractor):
 
     def login(self):
         """Login and set necessary cookies"""
-        username = self.config("username")
+        username, password = self.auth_info()
         if not username:
             self.log.info("no username given; using e-hentai.org")
             self.root = "https://e-hentai.org"
             self.original = False
             return
-        password = self.config("password")
         cookies = self._login_impl(username, password)
         for key, value in cookies.items():
             self.session.cookies.set(

gallery_dl/extractor/nijie.py

@@ -62,8 +62,7 @@ class NijieExtractor(AsynchronousExtractor):
 
     def login(self):
         """Login and obtain session cookie"""
-        username = self.config("username")
-        password = self.config("password")
+        username, password = self.auth_info()
         self.session.cookies = self._login_impl(username, password)
 
     @cache(maxage=30*24*60*60, keyarg=1)

gallery_dl/extractor/pixiv.py

@@ -233,8 +233,7 @@ class PixivAPI():
     def __init__(self, extractor):
         self.session = extractor.session
         self.log = extractor.log
-        self.username = extractor.config("username")
-        self.password = extractor.config("password")
+        self.username, self.password = extractor.auth_info()
         self.user_info = None
         self.session.headers.update({
             "Referer": "https://www.pixiv.net/",

gallery_dl/extractor/seiga.py

@@ -47,8 +47,7 @@ class SeigaExtractor(Extractor):
 
     def login(self):
         """Login and set necessary cookies"""
-        username = self.config("username")
-        password = self.config("password")
+        username, password = self.auth_info()
         self.session.cookies = self._login_impl(username, password)
 
     @cache(maxage=7*24*60*60, keyarg=1)

gallery_dl/option.py

@@ -86,6 +86,11 @@ def build_parser():
         "-p", "--password",
         metavar="PASS", action=ConfigAction, dest="password",
     )
+    parser.add_argument(
+        "--netrc",
+        action=ConfigConstAction, nargs=0, dest="netrc", const=True,
+        help="Use .netrc authentication data",
+    )
     parser.add_argument(
         "-i", "--input-file",
         metavar="FILE", dest="inputfile",