Add support for VSOCK

TODO.md

@@ -3,4 +3,12 @@
 ## Handling of negative return code
 
 In msocket, when stream data processing returns an error, its internal io_task thread breaks out of the loop and terminates immediately without calling msocket_common_on_disconnected().
-Can we improve this design?
+Can we improve this design?
+
+## TCP_NODELAY should be optional
+
+In msocket, all TCP sockets are automatically using TCP_NODELAY. This feature should be optional using a setting or config.
+
+## Remove state MSOCKET_STATE_ACCEPTING
+
+The MSOCKET_STATE_ACCEPTING doesn't serve any purpose except for debugging. It should be removed

include/msocket.h

@@ -56,6 +56,12 @@ typedef uint8_t msocket_state_t;
 #define MSOCKET_ADDR_INET           0u
 #define MSOCKET_ADDR_UNIX           1u
 #define MSOCKET_ADDR_INET6          3u
+#define MSOCKET_ADDR_VSOCK          4u
+
+#define MSOCKET_VMADDR_CID_ANY        0xFFFFFFFFU
+#define MSOCKET_VMADDR_CID_HYPERVISOR 0U
+#define MSOCKET_VMADDR_CID_LOCAL      1U
+#define MSOCKET_VMADDR_CID_HOST       2U
 
 #define MSOCKET_ADDRSTRLEN 46u
 
@@ -224,6 +230,16 @@ msocket_error_t msocket_listen(msocket_t *self, uint8_t mode, uint16_t port, con
  */
 msocket_error_t msocket_unix_listen(msocket_t *self, const char *socket_path);
 
+/**
+ * Binds and configures a listening VSOCK socket (Linux only).
+ *
+ * @param self Pointer to msocket_t instance.
+ * @param cid Context ID to bind to (e.g. MSOCKET_VMADDR_CID_ANY).
+ * @param port VSOCK port number to bind to.
+ * @return MSOCKET_NO_ERROR on success, or error code on failure.
+ */
+msocket_error_t msocket_vsock_listen(msocket_t *self, uint32_t cid, uint32_t port);
+
 /**
  * Accepts an incoming client connection on a listening TCP or UNIX socket.
  *
@@ -295,6 +311,19 @@ msocket_error_t msocket_connect(msocket_t *self, const char *addr, uint16_t port
  */
 msocket_error_t msocket_unix_connect(msocket_t *self, const char *socket_path);
 
+/**
+ * Initiates an outgoing VSOCK connection (Linux only).
+ *
+ * Requires a handler table to be registered beforehand via msocket_set_handler().
+ * Upon connection, the background I/O event loop is launched automatically.
+ *
+ * @param self Pointer to msocket_t instance.
+ * @param cid Target Context ID (e.g. MSOCKET_VMADDR_CID_HOST or specific guest CID).
+ * @param port Target VSOCK port.
+ * @return MSOCKET_NO_ERROR on success, or error code on failure.
+ */
+msocket_error_t msocket_vsock_connect(msocket_t *self, uint32_t cid, uint32_t port);
+
 /**
  * Sends data to a specific destination over UDP.
  *

include/msocket_server.h

@@ -35,6 +35,8 @@ typedef struct msocket_server_tag {
    uint16_t udp_port;
    char *udp_addr;
    char *socket_path;
+   uint32_t vsock_cid;
+   uint32_t vsock_port;
    adt_ary_t cleanup_items;
    uint8_t cleanup_stop;
    uint8_t address_family;
@@ -124,6 +126,15 @@ void msocket_server_start(msocket_server_t *self, const char *udp_addr, uint16_t
  */
 void msocket_server_unix_start(msocket_server_t *self, const char *socket_path);
 
+/**
+ * Binds a listening VSOCK socket and starts the server threads (Linux only).
+ *
+ * @param self Pointer to msocket_server_t instance.
+ * @param cid Context ID to bind to (e.g. MSOCKET_VMADDR_CID_ANY).
+ * @param port VSOCK port to listen on.
+ */
+void msocket_server_vsock_start(msocket_server_t *self, uint32_t cid, uint32_t port);
+
 /**
  * Binds and starts a listening TCP server with TLS enabled.
  *

source/msocket_common.c

@@ -113,6 +113,12 @@ msocket_error_t msocket_create(msocket_t *self, uint8_t address_family)
 #endif
       self->address_family = MSOCKET_ADDR_UNIX;
       break;
+   case MSOCKET_ADDR_VSOCK:
+#if defined(AF_VSOCK) && (AF_VSOCK != MSOCKET_ADDR_VSOCK)
+   case AF_VSOCK:
+#endif
+      self->address_family = MSOCKET_ADDR_VSOCK;
+      break;
    default:
       return MSOCKET_INVALID_ARGUMENT_ERROR;
    }
@@ -332,6 +338,14 @@ msocket_error_t msocket_unix_listen(msocket_t *self, const char *socket_path)
    return msocket_os_unix_listen(self, socket_path);
 }
 
+msocket_error_t msocket_vsock_listen(msocket_t *self, uint32_t cid, uint32_t port)
+{
+   if (self == NULL || self->address_family != MSOCKET_ADDR_VSOCK || port == 0u) {
+      return MSOCKET_INVALID_ARGUMENT_ERROR;
+   }
+   return msocket_os_vsock_listen(self, cid, port);
+}
+
 msocket_t *msocket_accept(msocket_t *self, msocket_t *child)
 {
    if (self == NULL || self->os == NULL || self->state != MSOCKET_STATE_LISTENING) {
@@ -351,6 +365,15 @@ msocket_t *msocket_accept(msocket_t *self, msocket_t *child)
    }
 
    msocket_os_mutex_lock(self->os);
+   if (self->state == MSOCKET_STATE_CLOSING) {
+      msocket_os_mutex_unlock(self->os);
+      if (placement_new) {
+         msocket_destroy(child);
+      } else {
+         msocket_delete(child);
+      }
+      return NULL;
+   }
    self->state = MSOCKET_STATE_ACCEPTING;
    os_socket_t accept_fd = self->os->tcp_sockfd;
    msocket_os_mutex_unlock(self->os);
@@ -364,6 +387,45 @@ msocket_t *msocket_accept(msocket_t *self, msocket_t *child)
       return NULL;
    }
 
+   while (1) {
+      fd_set readfds;
+      FD_ZERO(&readfds);
+      FD_SET(accept_fd, &readfds);
+
+      struct timeval timeout;
+      timeout.tv_sec = 0;
+      timeout.tv_usec = TIMEOUT_US;
+
+      int activity = select((int)accept_fd + 1, &readfds, NULL, NULL, &timeout);
+      if (activity > 0) {
+         break;
+      } else if (activity == 0) {
+         msocket_state_t state;
+         msocket_os_mutex_lock(self->os);
+         state = self->state;
+         msocket_os_mutex_unlock(self->os);
+
+         if (state == MSOCKET_STATE_CLOSING) {
+            if (placement_new) {
+               msocket_destroy(child);
+            } else {
+               msocket_delete(child);
+            }
+            return NULL;
+         }
+      } else {
+         if (OS_SOCKET_ERRNO_IS_INTR()) {
+            continue;
+         }
+         if (placement_new) {
+            msocket_destroy(child);
+         } else {
+            msocket_delete(child);
+         }
+         return NULL;
+      }
+   }
+
    os_socket_t sockfd;
    int one = 1;
    msocket_error_t result = MSOCKET_NO_ERROR;
@@ -392,6 +454,22 @@ msocket_t *msocket_accept(msocket_t *self, msocket_t *child)
          setsockopt(sockfd, IPPROTO_TCP, TCP_NODELAY, OS_SOCKOPT_CAST(&one), sizeof(one));
          child->os->tcp_sockfd = sockfd;
       }
+   } else if (self->address_family == MSOCKET_ADDR_VSOCK) {
+#if defined(__linux__) && defined(AF_VSOCK)
+      struct sockaddr_vm cli_addr_vm;
+      OS_SOCK_LEN_T cli_len = (OS_SOCK_LEN_T)sizeof(cli_addr_vm);
+      memset(&cli_addr_vm, 0, sizeof(cli_addr_vm));
+      sockfd = accept(accept_fd, (struct sockaddr *)&cli_addr_vm, &cli_len);
+      if (OS_SOCKET_IS_INVALID(sockfd)) {
+         result = MSOCKET_SOCKET_ERROR;
+      } else {
+         snprintf(child->stream_info.addr, MSOCKET_ADDRSTRLEN, "cid:%u", cli_addr_vm.svm_cid);
+         child->stream_info.port = (uint16_t)(cli_addr_vm.svm_port & 0xFFFF);
+         child->os->tcp_sockfd = sockfd;
+      }
+#else
+      result = MSOCKET_NOT_IMPLEMENTED_ERROR;
+#endif
    } else {
       struct sockaddr_in cli_addr;
       OS_SOCK_LEN_T cli_len = (OS_SOCK_LEN_T)sizeof(cli_addr);
@@ -542,6 +620,17 @@ msocket_error_t msocket_unix_connect(msocket_t *self, const char *socket_path)
    return msocket_os_unix_connect(self, socket_path);
 }
 
+msocket_error_t msocket_vsock_connect(msocket_t *self, uint32_t cid, uint32_t port)
+{
+   if (self == NULL || port == 0u || (self->socket_mode & MSOCKET_MODE_STREAM) != 0) {
+      return MSOCKET_INVALID_ARGUMENT_ERROR;
+   }
+   if (self->handler_table == NULL) {
+      return MSOCKET_INVALID_ARGUMENT_ERROR;
+   }
+   return msocket_os_vsock_connect(self, cid, port);
+}
+
 msocket_error_t msocket_send(msocket_t *self, const void *msg_data, uint32_t msg_len)
 {
    if (self == NULL || msg_data == NULL || (self->socket_mode & MSOCKET_MODE_STREAM) == 0) {

source/msocket_internal.h

@@ -82,6 +82,9 @@ typedef SOCKET os_socket_t;
 # include <unistd.h>
 # include <pthread.h>
 # include <semaphore.h>
+# if defined(__linux__)
+#  include <linux/vm_sockets.h>
+# endif
 
 /* Sockets */
 typedef int os_socket_t;
@@ -185,6 +188,9 @@ void msocket_os_mutex_unlock(msocket_os_t *os);
 msocket_error_t msocket_os_unix_listen(msocket_t *self, const char *socket_path);
 msocket_error_t msocket_os_unix_connect(msocket_t *self, const char *socket_path);
 
+msocket_error_t msocket_os_vsock_listen(msocket_t *self, uint32_t cid, uint32_t port);
+msocket_error_t msocket_os_vsock_connect(msocket_t *self, uint32_t cid, uint32_t port);
+
 //////////////////////////////////////////////////////////////////////////////
 // COMMON CALLBACKS FROM PLATFORM
 //////////////////////////////////////////////////////////////////////////////

source/msocket_posix.c

@@ -223,3 +223,91 @@ msocket_error_t msocket_os_unix_connect(msocket_t *self, const char *socket_path
    }
    return MSOCKET_NO_ERROR;
 }
+
+//////////////////////////////////////////////////////////////////////////////
+// VSOCK SOCKETS
+//////////////////////////////////////////////////////////////////////////////
+
+msocket_error_t msocket_os_vsock_listen(msocket_t *self, uint32_t cid, uint32_t port)
+{
+#if defined(__linux__) && defined(AF_VSOCK)
+   struct sockaddr_vm saddr;
+   int sockvsock;
+   int rc;
+
+   memset(&saddr, 0, sizeof(saddr));
+   saddr.svm_family = AF_VSOCK;
+   saddr.svm_cid = cid;
+   saddr.svm_port = port;
+
+   sockvsock = socket(AF_VSOCK, SOCK_STREAM, 0);
+   if (sockvsock < 0) {
+      return MSOCKET_SOCKET_ERROR;
+   }
+
+   rc = bind(sockvsock, (struct sockaddr *)&saddr, sizeof(saddr));
+   if (rc < 0) {
+      close(sockvsock);
+      return MSOCKET_SOCKET_ERROR;
+   }
+
+   rc = listen(sockvsock, 5);
+   if (rc < 0) {
+      close(sockvsock);
+      return MSOCKET_SOCKET_ERROR;
+   }
+
+   self->os->tcp_sockfd = sockvsock;
+   self->state = MSOCKET_STATE_LISTENING;
+   self->socket_mode |= MSOCKET_MODE_STREAM;
+   return MSOCKET_NO_ERROR;
+#else
+   (void)self;
+   (void)cid;
+   (void)port;
+   return MSOCKET_NOT_IMPLEMENTED_ERROR;
+#endif
+}
+
+msocket_error_t msocket_os_vsock_connect(msocket_t *self, uint32_t cid, uint32_t port)
+{
+#if defined(__linux__) && defined(AF_VSOCK)
+   struct sockaddr_vm saddr;
+   int sockfd = socket(AF_VSOCK, SOCK_STREAM, 0);
+   if (sockfd < 0) {
+      return MSOCKET_SOCKET_ERROR;
+   }
+
+   memset(&saddr, 0, sizeof(saddr));
+   saddr.svm_family = AF_VSOCK;
+   saddr.svm_cid = cid;
+   saddr.svm_port = port;
+
+   int rc = connect(sockfd, (struct sockaddr *)&saddr, sizeof(saddr));
+   if (rc < 0) {
+      close(sockfd);
+      return MSOCKET_SOCKET_ERROR;
+   }
+
+   snprintf(self->stream_info.addr, MSOCKET_ADDRSTRLEN, "cid:%u", cid);
+   self->stream_info.port = (uint16_t)(port & 0xFFFF);
+   self->os->tcp_sockfd = sockfd;
+   self->socket_mode |= MSOCKET_MODE_STREAM;
+   self->state = MSOCKET_STATE_ESTABLISHED;
+   self->os->new_connection = true;
+
+   msocket_error_t io_rc = msocket_start_io(self);
+   if (io_rc != MSOCKET_NO_ERROR) {
+      close(sockfd);
+      self->os->tcp_sockfd = -1;
+      self->state = MSOCKET_STATE_CLOSED;
+      return io_rc;
+   }
+   return MSOCKET_NO_ERROR;
+#else
+   (void)self;
+   (void)cid;
+   (void)port;
+   return MSOCKET_NOT_IMPLEMENTED_ERROR;
+#endif
+}

source/msocket_server.c

@@ -41,6 +41,8 @@ void msocket_server_create(msocket_server_t *self, uint8_t address_family, void
       self->udp_port = 0u;
       self->udp_addr = NULL;
       self->socket_path = NULL;
+      self->vsock_cid = 0u;
+      self->vsock_port = 0u;
       self->accept_socket = NULL;
       self->cleanup_stop = 0u;
       memset(&self->handler_table, 0, sizeof(self->handler_table));
@@ -169,6 +171,17 @@ void msocket_server_unix_start(msocket_server_t *self, const char *socket_path)
    }
 }
 
+void msocket_server_vsock_start(msocket_server_t *self, uint32_t cid, uint32_t port)
+{
+   if (self != NULL && port != 0u) {
+      self->tcp_port = 0u;
+      self->udp_port = 0u;
+      self->vsock_cid = cid;
+      self->vsock_port = port;
+      msocket_server_start_threads(self);
+   }
+}
+
 msocket_error_t msocket_server_start_tls(msocket_server_t *self, uint16_t tcp_port, const struct msocket_tls_config_tag *tls_config)
 {
 #if defined(MSOCKET_ENABLE_TLS)
@@ -258,6 +271,16 @@ static msocket_error_t msocket_server_bind(msocket_server_t *self)
       }
    }
 
+   if (self->vsock_port != 0u) {
+      rc = msocket_vsock_listen(self->accept_socket, self->vsock_cid, self->vsock_port);
+      if (rc != MSOCKET_NO_ERROR) {
+         fprintf(stderr, "[MSOCKET_SERVER] Failed to bind VSOCK port %u (CID %u)\n", self->vsock_port, self->vsock_cid);
+         msocket_delete(self->accept_socket);
+         self->accept_socket = NULL;
+         return rc;
+      }
+   }
+
    return MSOCKET_NO_ERROR;
 }