From 4d8ec3010049acf4dd1a9abacb06df5252a47b64 Mon Sep 17 00:00:00 2001
From: Witold Filipczyk <witekfl@poczta.onet.pl>
Date: Wed, 1 Jul 2015 13:06:04 +0200
Subject: [PATCH] Unix domain sockets support.

The socket is not removed on shutdown, but the rest seems to work.
---
 libhttp/server.c           | 41 ++++++++++++++++++++++++++++++++++++
 libhttp/server.h           |  9 ++++++++
 shellinabox/shellinaboxd.c | 43 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 93 insertions(+)

diff --git a/libhttp/server.c b/libhttp/server.c
index abe307f..d42326e 100644
--- a/libhttp/server.c
+++ b/libhttp/server.c
@@ -52,7 +52,9 @@
 #include <stdlib.h>
 #include <string.h>
 #include <sys/poll.h>
+#include <sys/stat.h>
 #include <sys/socket.h>
+#include <sys/un.h>
 #include <sys/time.h>
 #include <sys/types.h>
 #include <unistd.h>
@@ -138,8 +140,13 @@ int x_poll(struct pollfd *fds, nfds_t nfds, int timeout) {
 #define poll x_poll
 #endif
 
+char unixDomainSocket[UNIX_PATH_MAX];
 time_t currentTime;
 
+int unixDomainUser;
+int unixDomainGroup;
+int unixDomainChmod;
+
 struct PayLoad {
   int (*handler)(struct HttpConnection *, void *, const char *, int);
   void *arg;
@@ -283,6 +290,38 @@ void initServer(struct Server *server, int localhostOnly, int portMin,
   server->numConnections        = 0;
 
   int true                      = 1;
+
+  if (unixDomainSocket[0]) {
+    server->serverFd = socket(AF_UNIX, SOCK_STREAM, 0);
+    check(server->serverFd >= 0);
+    check(!setsockopt(server->serverFd, SOL_SOCKET, SO_REUSEADDR,
+                    &true, sizeof(true)));
+    struct sockaddr_un serverAddr = { 0 };
+
+    unlink(unixDomainSocket);
+
+    serverAddr.sun_family = AF_UNIX;
+    strcpy(serverAddr.sun_path, unixDomainSocket);
+    int servlen = sizeof(serverAddr.sun_family) + strlen(unixDomainSocket);
+
+    if (bind(server->serverFd, (struct sockaddr *)&serverAddr, servlen)) {
+        fatal("Failed to bind to unix socket");
+    }
+
+    check(!chown(unixDomainSocket, unixDomainUser, unixDomainGroup));
+    check(!chmod(unixDomainSocket, unixDomainChmod));
+
+    check(!listen(server->serverFd, SOMAXCONN));
+    check(server->pollFds         = malloc(sizeof(struct pollfd)));
+    server->pollFds->fd           = server->serverFd;
+    server->pollFds->events       = POLLIN;
+
+    initTrie(&server->handlers, serverDestroyHandlers, NULL);
+    serverRegisterStreamingHttpHandler(server, "/quit", serverQuitHandler, NULL);
+    initSSL(&server->ssl);
+    return;
+  }
+
   server->serverFd              = socket(PF_INET, SOCK_STREAM, 0);
   check(server->serverFd >= 0);
   check(!setsockopt(server->serverFd, SOL_SOCKET, SO_REUSEADDR,
@@ -347,6 +386,8 @@ void destroyServer(struct Server *server) {
     free(server->pollFds);
     destroyTrie(&server->handlers);
     destroySSL(&server->ssl);
+
+    if (unixDomainSocket[0]) unlink(unixDomainSocket);
   }
 }
 
diff --git a/libhttp/server.h b/libhttp/server.h
index 8900d99..ae7cc1b 100644
--- a/libhttp/server.h
+++ b/libhttp/server.h
@@ -52,6 +52,15 @@
 #include "libhttp/http.h"
 #include "libhttp/ssl.h"
 
+#ifndef UNIX_PATH_MAX
+#define UNIX_PATH_MAX 108
+#endif
+
+extern int unixDomainUser;
+extern int unixDomainGroup;
+extern int unixDomainChmod;
+extern char unixDomainSocket[UNIX_PATH_MAX];
+
 struct Server;
 
 struct ServerConnection {
diff --git a/shellinabox/shellinaboxd.c b/shellinabox/shellinaboxd.c
index c6f150e..3a69ac1 100644
--- a/shellinabox/shellinaboxd.c
+++ b/shellinabox/shellinaboxd.c
@@ -61,6 +61,9 @@
 #include <sys/resource.h>
 #include <sys/types.h>
 #include <sys/stat.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+
 #include <unistd.h>
 
 #ifdef HAVE_SYS_PRCTL_H
@@ -68,6 +71,7 @@
 #endif
 
 #include "libhttp/http.h"
+#include "libhttp/server.h"
 #include "logging/logging.h"
 #include "shellinabox/externalfile.h"
 #include "shellinabox/launcher.h"
@@ -785,6 +789,7 @@ static void usage(void) {
           "  -s, --service=SERVICE       define one or more services\n"
           "%s"
           "  -q, --quiet                 turn off all messages\n"
+          "      --unixdomain-only=PATH:USER:GROUP:CHMOD listen on unix socket\n"
           "  -u, --user=UID              switch to this user (default: %s)\n"
           "      --user-css=STYLES       defines user-selectable CSS options\n"
           "  -v, --verbose               enable logging messages\n"
@@ -891,6 +896,7 @@ static void parseArgs(int argc, char * const argv[]) {
       { "disable-ssl",      0, 0, 't' },
       { "disable-ssl-menu", 0, 0,  0  },
       { "quiet",            0, 0, 'q' },
+      { "unixdomain-only",  1, 0,  0, },
       { "user",             1, 0, 'u' },
       { "user-css",         1, 0,  0  },
       { "verbose",          0, 0, 'v' },
@@ -1126,6 +1132,43 @@ static void parseArgs(int argc, char * const argv[]) {
       }
       verbosity            = MSG_QUIET;
       logSetLogLevel(verbosity);
+    } else if (!idx--) {
+      // Unix domain only
+      if (!optarg || !*optarg) {
+        fatal("Option \"--unixdomain-only\" expects an argument.");
+      }
+      char *ptr, *s, *tmp;
+
+      s = optarg;
+      ptr = strchr(s, ':');
+      if (ptr == NULL) {
+         fatal("Syntax error in unixdomain-only definition \"%s\".", optarg);
+      }
+      check(ptr - s < UNIX_PATH_MAX);
+      memcpy(unixDomainSocket, s, ptr - s);
+      unixDomainSocket[ptr - s] = '\000';
+
+      s = ptr + 1;
+      ptr = strchr(s, ':');
+      if (ptr == NULL) {
+         fatal("Syntax error in unixdomain-only definition \"%s\".", optarg);
+      }
+      check(tmp = strndup(s, ptr - s));
+      unixDomainUser = parseUserArg(tmp, NULL);
+      free(tmp);
+
+      s = ptr + 1;
+      ptr = strchr(s, ':');
+      if (ptr == NULL) {
+         fatal("Syntax error in unixdomain-only definition \"%s\".", optarg);
+      }
+      check(tmp = strndup(s, ptr - s));
+      unixDomainGroup = parseGroupArg(tmp, NULL);
+      free(tmp);
+
+      s = ptr + 1;
+      unixDomainChmod = strtol(s, NULL, 0);
+
     } else if (!idx--) {
       // User
       if (runAsUser >= 0) {