From 216bd91050fe8d7c3c14a04d33e4ab15a03f5dba Mon Sep 17 00:00:00 2001
From: XANTRONIX Development <dev@xantronix.com>
Date: Sun, 19 Jul 2020 23:36:35 -0400
Subject: [PATCH] Let patty_kiss_tnc_new() use Unix domain sockets

Modify patty_kiss_tnc_new() to connect to a Unix domain socket
---
 src/kiss.c | 38 +++++++++++++++++++++++++++++++++++---
 1 file changed, 35 insertions(+), 3 deletions(-)

diff --git a/src/kiss.c b/src/kiss.c
index 0f734e2..897396c 100644
--- a/src/kiss.c
+++ b/src/kiss.c
@@ -5,7 +5,8 @@
 #include <unistd.h>
 #include <sys/types.h>
 #include <sys/stat.h>
-#include <sys/uio.h>
+#include <sys/socket.h>
+#include <sys/un.h>
 #include <errno.h>
 
 #include <patty/kiss.h>
@@ -66,9 +67,36 @@ error_malloc_tnc:
 patty_kiss_tnc *patty_kiss_tnc_new(const char *device) {
     patty_kiss_tnc *tnc;
     int fd;
+    struct stat st;
 
-    if ((fd = open(device, O_RDWR)) < 0) {
-        goto error_open;
+    if (stat(device, &st) < 0) {
+        goto error_stat;
+    }
+
+    if (st.st_mode & S_IFSOCK) {
+        struct sockaddr_un addr;
+
+        if (strlen(device) > sizeof(addr.sun_path)) {
+            errno = EOVERFLOW;
+
+            goto error_overflow;
+        }
+
+        if ((fd = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) {
+            goto error_socket;
+        }
+
+        memset(&addr, '\0', sizeof(addr));
+        addr.sun_family = AF_UNIX;
+        strncpy(addr.sun_path, device, sizeof(addr.sun_path));
+
+        if (connect(fd, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
+            goto error_connect;
+        }
+    } else {
+        if ((fd = open(device, O_RDWR)) < 0) {
+            goto error_open;
+        }
     }
 
     if ((tnc = patty_kiss_tnc_new_fd(fd)) == NULL) {
@@ -80,9 +108,13 @@ patty_kiss_tnc *patty_kiss_tnc_new(const char *device) {
     return tnc;
 
 error_tnc_new_fd:
+error_connect:
     close(fd);
 
+error_socket:
+error_overflow:
 error_open:
+error_stat:
     return NULL;
 }