add initial vsock support

This adds the ability to create and use vsock sockets, which can serve
as a communication mechanism between multiple VMs or VM and host.

VSOCK are not available everywhere, so this feature is guarded by the
USE_VSOCK flags and test to check vsock functionality requires the
local CID feature, available on Linux 5.6+ with the vsock_loopback
driver.

Signed-off-by: Petre Eftime <[email protected]>

CMakeLists.txt

@@ -95,6 +95,10 @@ if (WIN32)
     set(TLS_STACK_DETERMINED ON)
 
 elseif (CMAKE_SYSTEM_NAME STREQUAL "Linux" OR CMAKE_SYSTEM_NAME STREQUAL "Android")
+    option(USE_VSOCK
+	    "Build in support for VSOCK sockets"
+	    OFF)
+
     file(GLOB AWS_IO_OS_HEADERS
             )
 
@@ -194,6 +198,10 @@ if (BUILD_RELOCATABLE_BINARIES)
     target_compile_definitions(${PROJECT_NAME} PRIVATE "-DCOMPAT_MODE")
 endif()
 
+if (USE_VSOCK)
+	target_compile_definitions(${PROJECT_NAME} PUBLIC "-DUSE_VSOCK")
+endif()
+
 target_include_directories(${PROJECT_NAME} PUBLIC
         $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>
         $<INSTALL_INTERFACE:include>)

README.md

@@ -668,6 +668,7 @@ notifications.
         AWS_SOCKET_IPV4,
         AWS_SOCKET_IPV6,
         AWS_SOCKET_LOCAL,
+        AWS_SOCKET_VSOCK,
     } aws_socket_domain;
 
 `AWS_SOCKET_IPV4` means an IPv4 address will be used.
@@ -681,6 +682,7 @@ notifications.
         AWS_SOCKET_DGRAM
     } aws_socket_type;
 
+`AWS_SOCKET_VSOCK` means a CID address will be used. Note: VSOCK is currently only available on Linux with an appropriate VSOCK kernel driver installed. `-DUSE_VSOCK` needs to be passed during compilation to enable VSOCK support.
 
 `AWS_SOCKET_STREAM` is TCP or a connection oriented socket.
 
@@ -709,7 +711,7 @@ with it.
         char port[10];
     };
 
-`address` can be either an IPv4 or IPv6 address. This can be used for UDP or TCP.
+`address` can be either an IPv4, IPv6 or VSOCK CID address. This can be used for UDP or TCP.
 `socket_name` is only used in LOCAL mode.
 `port` can be used for TCP or UDP.
 

include/aws/io/socket.h

@@ -13,6 +13,8 @@ enum aws_socket_domain {
     AWS_SOCKET_IPV6,
     /* Unix domain sockets (or at least something like them) */
     AWS_SOCKET_LOCAL,
+    /* VSOCK used in inter-VM communication */
+    AWS_SOCKET_VSOCK,
 };
 
 enum aws_socket_type {
@@ -22,7 +24,7 @@ enum aws_socket_type {
     AWS_SOCKET_STREAM,
     /* A datagram socket is connectionless and sends unreliable messages.
      * This means UDP when used with IPV4/6.
-     * LOCAL sockets are not compatible with DGRAM.*/
+     * LOCAL and VSOCK sockets are not compatible with DGRAM.*/
     AWS_SOCKET_DGRAM,
 };
 
@@ -152,7 +154,7 @@ AWS_IO_API void aws_socket_clean_up(struct aws_socket *socket);
  * Connects to a remote endpoint. In UDP, this simply binds the socket to a remote address for use with
  * `aws_socket_write()`, and if the operation is successful, the socket can immediately be used for write operations.
  *
- * In TCP amd LOCAL, this function will not block. If the return value is successful, then you must wait on the
+ * In TCP, LOCAL and VSOCK this function will not block. If the return value is successful, then you must wait on the
  * `on_connection_result()` callback to be invoked before using the socket.
  *
  * If an event_loop is provided for UDP sockets, a notification will be sent on
@@ -175,12 +177,12 @@ AWS_IO_API int aws_socket_connect(
 AWS_IO_API int aws_socket_bind(struct aws_socket *socket, const struct aws_socket_endpoint *local_endpoint);
 
 /**
- * TCP and LOCAL only. Sets up the socket to listen on the address bound to in `aws_socket_bind()`.
+ * TCP, LOCAL and VSOCK only. Sets up the socket to listen on the address bound to in `aws_socket_bind()`.
  */
 AWS_IO_API int aws_socket_listen(struct aws_socket *socket, int backlog_size);
 
 /**
- * TCP and LOCAL only. The socket will begin accepting new connections. This is an asynchronous operation. New
+ * TCP, LOCAL and VSOCK only. The socket will begin accepting new connections. This is an asynchronous operation. New
  * connections or errors will arrive via the `on_accept_result` callback.
  *
  * aws_socket_bind() and aws_socket_listen() must be called before calling this function.
@@ -192,7 +194,7 @@ AWS_IO_API int aws_socket_start_accept(
     void *user_data);
 
 /**
- * TCP and LOCAL only. The listening socket will stop accepting new connections.
+ * TCP, LOCAL and VSOCK only. The listening socket will stop accepting new connections.
  * It is safe to call `aws_socket_start_accept()` again after
  * this operation. This can be called from any thread but be aware,
  * on some platforms, if you call this from outside of the current event loop's thread, it will block

source/posix/socket.c

@@ -39,6 +39,14 @@
 #    define O_CLOEXEC 02000000
 #endif
 
+#ifdef USE_VSOCK
+#    if defined(__linux__) && defined(AF_VSOCK)
+#        include <linux/vm_sockets.h>
+#    else
+#        error "USE_VSOCK not supported on current platform"
+#    endif
+#endif
+
 /* other than CONNECTED_READ | CONNECTED_WRITE
  * a socket is only in one of these states at a time. */
 enum socket_state {
@@ -61,6 +69,10 @@ static int s_convert_domain(enum aws_socket_domain domain) {
             return AF_INET6;
         case AWS_SOCKET_LOCAL:
             return AF_UNIX;
+#ifdef USE_VSOCK
+        case AWS_SOCKET_VSOCK:
+            return AF_VSOCK;
+#endif
         default:
             AWS_ASSERT(0);
             return AF_INET;
@@ -498,9 +510,46 @@ struct socket_address {
         struct sockaddr_in addr_in;
         struct sockaddr_in6 addr_in6;
         struct sockaddr_un un_addr;
+#ifdef USE_VSOCK
+        struct sockaddr_vm vm_addr;
+#endif
     } sock_addr_types;
 };
 
+#ifdef USE_VSOCK
+/** Convert a string to a VSOCK CID. Respects the calling convetion of inet_pton:
+ * 0 on error, 1 on success. */
+static int parse_cid(const char *cid_str, unsigned int *value) {
+    if (cid_str == NULL || value == NULL) {
+        errno = EINVAL;
+        return 0;
+    }
+    /* strtoll returns 0 as both error and correct value */
+    errno = 0;
+    /* unsigned long long to handle edge cases in convention explicitly */
+    long long cid = strtoll(cid_str, NULL, 10);
+    if (errno != 0) {
+        return 0;
+    }
+
+    /* -1U means any, so it's a valid value, but it needs to be converted to
+     * unsigned int. */
+    if (cid == -1) {
+        *value = VMADDR_CID_ANY;
+        return 1;
+    }
+
+    if (cid < 0 || cid > UINT_MAX) {
+        errno = ERANGE;
+        return 0;
+    }
+
+    /* cast is safe here, edge cases already checked */
+    *value = (unsigned int)cid;
+    return 1;
+}
+#endif
+
 int aws_socket_connect(
     struct aws_socket *socket,
     const struct aws_socket_endpoint *remote_endpoint,
@@ -551,6 +600,13 @@ int aws_socket_connect(
         address.sock_addr_types.un_addr.sun_family = AF_UNIX;
         strncpy(address.sock_addr_types.un_addr.sun_path, remote_endpoint->address, AWS_ADDRESS_MAX_LEN);
         sock_size = sizeof(address.sock_addr_types.un_addr);
+#ifdef USE_VSOCK
+    } else if (socket->options.domain == AWS_SOCKET_VSOCK) {
+        pton_err = parse_cid(remote_endpoint->address, &address.sock_addr_types.vm_addr.svm_cid);
+        address.sock_addr_types.vm_addr.svm_family = AF_VSOCK;
+        address.sock_addr_types.vm_addr.svm_port = (unsigned int)remote_endpoint->port;
+        sock_size = sizeof(address.sock_addr_types.vm_addr);
+#endif
     } else {
         AWS_ASSERT(0);
         return aws_raise_error(AWS_IO_SOCKET_UNSUPPORTED_ADDRESS_FAMILY);
@@ -718,6 +774,13 @@ int aws_socket_bind(struct aws_socket *socket, const struct aws_socket_endpoint
         address.sock_addr_types.un_addr.sun_family = AF_UNIX;
         strncpy(address.sock_addr_types.un_addr.sun_path, local_endpoint->address, AWS_ADDRESS_MAX_LEN);
         sock_size = sizeof(address.sock_addr_types.un_addr);
+#ifdef USE_VSOCK
+    } else if (socket->options.domain == AWS_SOCKET_VSOCK) {
+        pton_err = parse_cid(local_endpoint->address, &address.sock_addr_types.vm_addr.svm_cid);
+        address.sock_addr_types.vm_addr.svm_family = AF_VSOCK;
+        address.sock_addr_types.vm_addr.svm_port = (unsigned int)local_endpoint->port;
+        sock_size = sizeof(address.sock_addr_types.vm_addr);
+#endif
     } else {
         AWS_ASSERT(0);
         return aws_raise_error(AWS_IO_SOCKET_UNSUPPORTED_ADDRESS_FAMILY);

tests/CMakeLists.txt

@@ -53,6 +53,9 @@ add_test_case(udp_socket_communication)
 add_test_case(udp_bind_connect_communication)
 add_net_test_case(connect_timeout)
 add_net_test_case(connect_timeout_cancelation)
+if (USE_VSOCK)
+	add_test_case(vsock_loopback_socket_communication)
+endif ()
 
 add_test_case(outgoing_local_sock_errors)
 add_test_case(outgoing_tcp_sock_error)

tests/socket_test.c

@@ -24,6 +24,10 @@
 #    pragma warning(disable : 4996) /* sprintf */
 #endif
 
+#if USE_VSOCK
+#    include <linux/vm_sockets.h>
+#endif
+
 struct local_listener_args {
     struct aws_socket *incoming;
     struct aws_mutex *mutex;
@@ -432,6 +436,30 @@ static int s_test_tcp_socket_communication(struct aws_allocator *allocator, void
 
 AWS_TEST_CASE(tcp_socket_communication, s_test_tcp_socket_communication)
 
+#if defined(USE_VSOCK)
+static int s_test_vsock_loopback_socket_communication(struct aws_allocator *allocator, void *ctx) {
+/* Without vsock loopback it's difficult to test vsock functionality.
+ * Also note that having this defined does not guarantee that it's available
+ * for use and there's no path to figure out dynamically if it can be used. */
+#    if defined(VMADDR_CID_LOCAL)
+    (void)ctx;
+
+    struct aws_socket_options options;
+    AWS_ZERO_STRUCT(options);
+    options.connect_timeout_ms = 3000;
+    options.type = AWS_SOCKET_STREAM;
+    options.domain = AWS_SOCKET_VSOCK;
+
+    struct aws_socket_endpoint endpoint = {.address = "1" /* VMADDR_CID_LOCAL */, .port = 8127};
+
+    return s_test_socket(allocator, &options, &endpoint);
+#    endif
+    return 0;
+}
+
+AWS_TEST_CASE(vsock_loopback_socket_communication, s_test_vsock_loopback_socket_communication)
+#endif
+
 static int s_test_udp_socket_communication(struct aws_allocator *allocator, void *ctx) {
     (void)ctx;