sauron: add Tor proxy support

Signed-off-by: Antoine Poinsot <darosior@protonmail.com>

sauron/README.md

@@ -23,3 +23,12 @@ Here is a fully reptilian example running against [blockstream.info](https://blo
 ```
 lightningd --mainnet --disable-plugin bcli --plugin $PWD/sauron.py --sauron-api-endpoint https://blockstream.info/api/
 ```
+
+You can use also proxy your requests through [Tor](https://www.torproject.org/) by
+specifying a SOCKS proxy to use with the `--sauron-tor-proxy` startup option, in
+the form `address:port`.
+
+Hidden services are also supported :
+```
+lightningd --testnet --disable-plugin bcli --plugin $PWD/sauron.py --sauron-tor-proxy localhost:9050 --sauron-api-endpoint http://explorerzydxu5ecjrkwceayqybizmpjjznk5izmitf2modhcusuqlid.onion/testnet/api/
+```

sauron/requirements.txt

@@ -1,2 +1,3 @@
 pyln-client>=0.7.3
-requests>=2.0.0
+requests>=2.23.0
+requests[socks]>=2.23.0

sauron/sauron.py

@@ -6,20 +6,40 @@ from art import sauron_eye
 from pyln.client import Plugin
 
 
-plugin = Plugin()
+plugin = Plugin(dynamic=False)
+plugin.sauron_socks_proxies = None
 
 
 class SauronError(Exception):
     pass
 
 
+def fetch(url):
+    """Fetch this {url}, maybe through a pre-defined proxy."""
+    # FIXME: Maybe try to be smart and renew circuit to broadcast different
+    # transactions ? Hint: lightningd will agressively send us the same
+    # transaction a certain amount of times.
+    session = requests.session()
+    session.proxies = plugin.sauron_socks_proxies
+    return session.get(url)
+
+
 @plugin.init()
 def init(plugin, options, configuration, **kwargs):
-    plugin.api_endpoint = options.get("sauron-api-endpoint")
+    plugin.api_endpoint = options["sauron-api-endpoint"]
     if not plugin.api_endpoint:
         raise SauronError("You need to specify the sauron-api-endpoint option.")
         sys.exit(1)
 
+    if options["sauron-tor-proxy"]:
+        address, port = options["sauron-tor-proxy"].split(":")
+        socks5_proxy = "socks5h://{}:{}".format(address, port)
+        plugin.sauron_socks_proxies = {
+            "http": socks5_proxy,
+            "https": socks5_proxy,
+        }
+        plugin.log("Using proxy {} for requests".format(socks5_proxy))
+
     plugin.log("Sauron plugin initialized")
     plugin.log(sauron_eye)
 
@@ -37,14 +57,14 @@ def getchaininfo(plugin, **kwargs):
         "regtest"
     }
 
-    genesis_req = requests.get(blockhash_url)
+    genesis_req = fetch(blockhash_url)
     if not genesis_req.status_code == 200:
         raise SauronError("Endpoint at {} returned {} ({}) when trying to "
                           "get genesis block hash."
                           .format(blockhash_url, genesis_req.status_code,
                                   genesis_req.text))
 
-    blockcount_req = requests.get(blockcount_url)
+    blockcount_req = fetch(blockcount_url)
     if not blockcount_req.status_code == 200:
         raise SauronError("Endpoint at {} returned {} ({}) when trying to "
                           "get blockcount.".format(blockcount_url,
@@ -67,9 +87,9 @@ def getchaininfo(plugin, **kwargs):
 def getrawblock(plugin, height, **kwargs):
     blockhash_url = "{}/block-height/{}".format(plugin.api_endpoint, height)
 
-    blockhash_req = requests.get(blockhash_url)
-    block_req = requests.get("{}/block/{}/raw".format(plugin.api_endpoint,
-                                                      blockhash_req.text))
+    blockhash_req = fetch(blockhash_url)
+    block_req = fetch("{}/block/{}/raw".format(plugin.api_endpoint,
+                                                     blockhash_req.text))
     if blockhash_req.status_code != 200 or block_req.status_code != 200:
         return {
             "blockhash": None,
@@ -104,13 +124,13 @@ def getutxout(plugin, txid, vout, **kwargs):
     gettx_url = "{}/tx/{}".format(plugin.api_endpoint, txid)
     status_url = "{}/tx/{}/outspend/{}".format(plugin.api_endpoint, txid, vout)
 
-    gettx_req = requests.get(gettx_url)
+    gettx_req = fetch(gettx_url)
     if not gettx_req.status_code == 200:
         raise SauronError("Endpoint at {} returned {} ({}) when trying to "
                           "get transaction.".format(gettx_url,
                                                     gettx_req.status_code,
                                                     gettx_req.text))
-    status_req = requests.get(status_url)
+    status_req = fetch(status_url)
     if not status_req.status_code == 200:
         raise SauronError("Endpoint at {} returned {} ({}) when trying to "
                           "get utxo status.".format(status_url,
@@ -134,7 +154,7 @@ def getutxout(plugin, txid, vout, **kwargs):
 def getfeerate(plugin, **kwargs):
     feerate_url = "{}/fee-estimates".format(plugin.api_endpoint)
 
-    feerate_req = requests.get(feerate_url)
+    feerate_req = fetch(feerate_url)
     assert feerate_req.status_code == 200
     feerates = feerate_req.json()
     # It renders sat/vB, we want sat/kVB, so multiply everything by 10**3
@@ -161,4 +181,13 @@ plugin.add_option(
     "The URL of the esplora instance to hit (including '/api')."
 )
 
+plugin.add_option(
+    "sauron-tor-proxy",
+    "",
+    "Tor's SocksPort address in the form address:port, don't specify the"
+    " protocol.  If you didn't modify your torrc you want to put"
+    "'localhost:9050' here."
+)
+
+
 plugin.run()