support systemd socket activation (fd passing) (#515)

* add support for socket passing
* slight tweaks before merge

---------

Signed-off-by: mat <matheuz1210@gmail.com>
Signed-off-by: ed <s@ocv.me>
Co-authored-by: ed <s@ocv.me>

copyparty/__main__.py

@@ -536,7 +536,7 @@ def get_sects():
             dedent(
                 """
             \033[33m-i\033[0m takes a comma-separated list of interfaces to listen on;
-            IP-addresses and/or unix-sockets (Unix Domain Sockets)
+            IP-addresses, unix-sockets and/or open file descriptors
 
             the default (\033[32m-i ::\033[0m) means all IPv4 and IPv6 addresses
 
@@ -562,7 +562,9 @@ def get_sects():
             \033[32m-i unix:\033[33m/dev/shm/party.sock\033[0m keeps umask-defined permission
             (usually \033[33m0600\033[0m) and the same user/group as copyparty
 
-            \033[33m-p\033[0m (tcp ports) is ignored for unix sockets
+            \033[32m-i fd:\033[33m3\033[0m uses the socket passed to copyparty on file descriptor 3
+
+            \033[33m-p\033[0m (tcp ports) is ignored for non ip-addresses
             """
             ),
         ],

copyparty/ftpd.py

@@ -607,7 +607,7 @@ class Ftpd(object):
         if "::" in ips:
             ips.append("0.0.0.0")
 
-        ips = [x for x in ips if "unix:" not in x]
+        ips = [x for x in ips if not x.startswith(("unix:", "fd:"))]
 
         if self.args.ftp4:
             ips = [x for x in ips if ":" not in x]

copyparty/svchub.py

@@ -868,7 +868,7 @@ class SvcHub(object):
 
         have_tcp = False
         for zs in al.i:
-            if not zs.startswith("unix:"):
+            if not zs.startswith(("unix:", "fd:")):
                 have_tcp = True
         if not have_tcp:
             zb = False
@@ -878,7 +878,7 @@ class SvcHub(object):
                     setattr(al, zs, False)
                     zb = True
             if zb:
-                t = "only listening on unix-sockets; cannot enable zeroconf/mdns/ssdp as requested"
+                t = "no ip addresses provided; cannot enable zeroconf/mdns/ssdp as requested"
                 self.log("root", t, 3)
 
         if not self.args.no_dav:

copyparty/tcpsrv.py

@@ -25,8 +25,8 @@ from .util import (
     termsize,
 )
 
-if True:
-    from typing import Generator, Union
+if True:  # pylint: disable=using-constant-test
+    from typing import Generator, Optional, Union
 
 if TYPE_CHECKING:
     from .svchub import SvcHub
@@ -245,8 +245,10 @@ class TcpSrv(object):
 
     def _listen(self, ip: str, port: int) -> None:
         uds_perm = uds_gid = -1
+        bound: Optional[socket.socket] = None
+        tcp = False
+
         if "unix:" in ip:
-            tcp = False
             ipv = socket.AF_UNIX
             uds = ip.split(":")
             ip = uds[-1]
@@ -259,7 +261,12 @@ class TcpSrv(object):
                     import grp
 
                     uds_gid = grp.getgrnam(uds[2]).gr_gid
+        elif "fd:" in ip:
+            fd = ip[3:]
+            bound = socket.socket(fileno=int(fd))
 
+            tcp = bound.proto == socket.IPPROTO_TCP
+            ipv = bound.family
         elif ":" in ip:
             tcp = True
             ipv = socket.AF_INET6
@@ -267,7 +274,7 @@ class TcpSrv(object):
             tcp = True
             ipv = socket.AF_INET
 
-        srv = socket.socket(ipv, socket.SOCK_STREAM)
+        srv = bound or socket.socket(ipv, socket.SOCK_STREAM)
 
         if not ANYWIN or self.args.reuseaddr:
             srv.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
@@ -285,6 +292,10 @@ class TcpSrv(object):
         if getattr(self.args, "freebind", False):
             srv.setsockopt(socket.SOL_IP, socket.IP_FREEBIND, 1)
 
+        if bound:
+            self.srv.append(srv)
+            return
+
         try:
             if tcp:
                 srv.bind((ip, port))
@@ -437,7 +448,7 @@ class TcpSrv(object):
     def detect_interfaces(self, listen_ips: list[str]) -> dict[str, Netdev]:
         from .stolen.ifaddr import get_adapters
 
-        listen_ips = [x for x in listen_ips if "unix:" not in x]
+        listen_ips = [x for x in listen_ips if not x.startswith(("unix:", "fd:"))]
 
         nics = get_adapters(True)
         eps: dict[str, Netdev] = {}

copyparty/tftpd.py

@@ -179,7 +179,7 @@ class Tftpd(object):
         if "::" in ips:
             ips.append("0.0.0.0")
 
-        ips = [x for x in ips if "unix:" not in x]
+        ips = [x for x in ips if not x.startswith(("unix:", "fd:"))]
 
         if self.args.tftp4:
             ips = [x for x in ips if ":" not in x]