apps/CMakeLists.txt

@@ -43,3 +43,4 @@ luna_app(kill.cpp kill)
 luna_app(gol.cpp gol)
 luna_app(buffer-test.cpp buffer-test)
 luna_app(socket-test.cpp socket-test)
+luna_app(socket-client.cpp socket-client)

apps/socket-client.cpp

@@ -0,0 +1,40 @@
+#include <stdio.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <unistd.h>
+
+int main()
+{
+    int sockfd = socket(AF_UNIX, SOCK_STREAM, 0);
+    if (sockfd < 0)
+    {
+        perror("socket");
+        return 0;
+    }
+
+    struct sockaddr_un un;
+    un.sun_family = AF_UNIX;
+    strncpy(un.sun_path, "/tmp/local.sock", sizeof(un.sun_path));
+
+    if (connect(sockfd, (struct sockaddr*)&un, sizeof(un)) < 0)
+    {
+        perror("connect");
+        return 1;
+    }
+
+    char buf[4096];
+    ssize_t nread = read(sockfd, buf, sizeof(buf) - 1);
+    if (nread > 0)
+    {
+        buf[nread] = 0;
+        printf("Message from server: %s\n", buf);
+    }
+
+    const char* message = "EXIT";
+    write(sockfd, message, strlen(message));
+
+    close(sockfd);
+
+    return 0;
+}

apps/socket-test.cpp

@@ -1,10 +1,18 @@
+#include <errno.h>
 #include <stdio.h>
 #include <string.h>
 #include <sys/socket.h>
+#include <sys/stat.h>
 #include <sys/un.h>
+#include <unistd.h>
 
 int main()
 {
+    setgid(1000);
+    setuid(1000);
+
+    remove("/tmp/local.sock");
+
     int sockfd = socket(AF_UNIX, SOCK_STREAM, 0);
     if (sockfd < 0)
     {
@@ -21,4 +29,47 @@ int main()
         perror("bind");
         return 1;
     }
+
+    if (listen(sockfd, 10) < 0)
+    {
+        perror("listen");
+        return 1;
+    }
+
+    while (1)
+    {
+        int fd = accept(sockfd, NULL, NULL);
+        if (fd < 0)
+        {
+            perror("accept");
+            return 1;
+        }
+
+        puts("New connection from client, sending hello");
+
+        const char* message = "Hello, client!";
+        write(fd, message, strlen(message));
+
+        puts("Now waiting for client to message back");
+
+        char buf[4096];
+        ssize_t nread = read(fd, buf, sizeof(buf) - 1);
+        if (nread >= 0)
+        {
+            buf[nread] = 0;
+            printf("Message from client: %s\n", buf);
+            if (!strcasecmp(buf, "exit"))
+            {
+                close(fd);
+                close(sockfd);
+                remove("/tmp/local.sock");
+                return 0;
+            }
+        }
+        else { printf("Error reading from client: %s\n", strerror(errno)); }
+
+        puts("Transmission ended, closing connection");
+
+        close(fd);
+    }
 }

base/etc/init/98-listen

@@ -0,0 +1,6 @@
+Name=listen
+Description=Start a Unix domain socket test server.
+Command=/usr/bin/socket-test
+StandardOutput=/dev/uart0
+StandardError=/dev/uart0
+Restart=true