Add support for httpd systemd socket activation

maxnet · maxnet · commit 016029979c33 · 2021-12-12T16:27:07.000+01:00
If a second socket is passed through systemd, assume it is meant
for httpd use.

Using it requires systemd units among the lines of:

/lib/systemd/system/x11vnc.service

==
[Unit]
Description=VNC server
Requires=x11vnc.socket

[Service]
Type=simple
ExecStart=/usr/local/bin/x11vnc -httpdir /usr/share/novnc -no6 -xkb -repeat -auth guess -display WAIT:0 -forever -shared
==

/lib/systemd/system/x11vnc.socket

==
[Unit]
Description=VNC server socket

[Socket]
ListenStream=5900
ListenStream=80

[Install]
WantedBy=sockets.target
==

systemctl enable --now x11vnc.socket

Signed-off-by: Floris Bos &lt;bos@je-eigen-domein.nl&gt;
diff --git a/libvncserver/httpd.c b/libvncserver/httpd.c
@@ -63,6 +63,10 @@
 #include <tcpd.h>
 #endif
 
+#ifdef LIBVNCSERVER_WITH_SYSTEMD
+#include <systemd/sd-daemon.h>
+#endif
+
 
 #define NOT_FOUND_STR "HTTP/1.0 404 Not found\r\nConnection: close\r\n\r\n" \
     "<HEAD><TITLE>File Not Found</TITLE></HEAD>\n" \
@@ -100,6 +104,33 @@ rfbHttpInitSockets(rfbScreenInfoPtr rfbScreen)
     if (!rfbScreen->httpDir)
 	return;
 
+#ifdef LIBVNCSERVER_WITH_SYSTEMD
+    if (sd_listen_fds(0) == 2) {
+        rfbSocket sock = SD_LISTEN_FDS_START + 1;
+        if (sd_is_socket(sock, AF_UNSPEC, 0, 0)) {
+            rfbErr("Systemd socket activation passed 'accept=yes' inetd style socket. Only passing listening sockets is supported for http socket\n");
+        } else if (sd_is_socket(sock, AF_UNSPEC, 0, 1)) {
+            struct sockaddr_storage sa;
+            int sa_len = sizeof(sa);
+            char hoststr[NI_MAXHOST];
+            char portstr[NI_MAXSERV];
+
+            if (getsockname(sock, (struct sockaddr *) &sa, &sa_len) == 0
+                && getnameinfo((struct sockaddr *)&sa, sa_len, hoststr, sizeof(hoststr),
+                                portstr, sizeof(portstr), NI_NUMERICHOST | NI_NUMERICSERV) == 0) {
+                rfbLog("Socket activation through systemd. Listening for HTTP connections on %s:%s\n", hoststr, portstr);
+                rfbScreen->port = atoi(portstr);
+            } else {
+                rfbLogPerror("Error retrieving nameinfo of socket received from systemd\n");
+            }
+
+            rfbScreen->httpListenSock = sock;
+        }
+
+        return;
+    }
+#endif
+
     if (rfbScreen->httpPort == 0) {
 	rfbScreen->httpPort = rfbScreen->port-100;
     }
diff --git a/libvncserver/sockets.c b/libvncserver/sockets.c
@@ -178,7 +178,7 @@ rfbInitSockets(rfbScreenInfoPtr rfbScreen)
     rfbScreen->socketState = RFB_SOCKET_READY;
 
 #ifdef LIBVNCSERVER_WITH_SYSTEMD
-    if (sd_listen_fds(0) == 1)
+    if (sd_listen_fds(0) == 1 || sd_listen_fds(0) == 2)
     {
         rfbSocket sock = SD_LISTEN_FDS_START + 0;
         if (sd_is_socket(sock, AF_UNSPEC, 0, 0))
@@ -202,7 +202,6 @@ rfbInitSockets(rfbScreenInfoPtr rfbScreen)
             rfbScreen->listenSock = sock;
             FD_SET(rfbScreen->listenSock, &(rfbScreen->allFds));
             rfbScreen->maxFd = rfbScreen->listenSock;
-            rfbProcessNewConnection(rfbScreen);
         }
         return;
     }

Original file line number	Diff line number	Diff line change
`@@ -178,7 +178,7 @@ rfbInitSockets(rfbScreenInfoPtr rfbScreen)`
`178`	`178`	`rfbScreen->socketState = RFB_SOCKET_READY;`
`179`	`179`
`180`	`180`	`#ifdef LIBVNCSERVER_WITH_SYSTEMD`
`181`		`- if (sd_listen_fds(0) == 1)`
	`181`	`+ if (sd_listen_fds(0) == 1 \|\| sd_listen_fds(0) == 2)`
`182`	`182`	`{`
`183`	`183`	`rfbSocket sock = SD_LISTEN_FDS_START + 0;`
`184`	`184`	`if (sd_is_socket(sock, AF_UNSPEC, 0, 0))`
`@@ -202,7 +202,6 @@ rfbInitSockets(rfbScreenInfoPtr rfbScreen)`
`202`	`202`	`rfbScreen->listenSock = sock;`
`203`	`203`	`FD_SET(rfbScreen->listenSock, &(rfbScreen->allFds));`
`204`	`204`	`rfbScreen->maxFd = rfbScreen->listenSock;`
`205`		`- rfbProcessNewConnection(rfbScreen);`
`206`	`205`	`}`
`207`	`206`	`return;`
`208`	`207`	`}`