Support connect() for tcp wrapper

[stevenengler]

The logic generally follows the logic from src/main/host/syscall/socket.c.

shadow/src/main/host/syscall/socket.c

Lines 784 to 901 in a8f4901

	SysCallReturn syscallhandler_connect(SysCallHandler* sys,
	const SysCallArgs* args) {
	int sockfd = args->args[0].as_i64;
	PluginPtr addrPtr = args->args[1].as_ptr; // const struct sockaddr*
	socklen_t addrlen = args->args[2].as_u64;
	trace("trying to connect on socket %i", sockfd);
	/* Get and validate the socket. */
	LegacySocket* socket_desc = NULL;
	int errcode =
	_syscallhandler_validateSocketHelper(sys, sockfd, &socket_desc);
	if (errcode < 0) {
	return syscallreturn_makeDoneErrno(-errcode);
	}
	utility_debugAssert(socket_desc);
	/* TODO: we assume AF_INET here, change this when we support AF_UNIX */
	// size_t unix_len = sizeof(struct sockaddr_un); // if sa_family==AF_UNIX
	size_t inet_len = sizeof(struct sockaddr_in);
	if (addrlen < inet_len) {
	return syscallreturn_makeDoneErrno(EINVAL);
	}
	const struct sockaddr* addr =
	process_getReadablePtr(_syscallhandler_getProcess(sys), addrPtr, addrlen);
	if (!addr) {
	debug("Couldn't read addr %p", (void*)addrPtr.val);
	return syscallreturn_makeDoneErrno(EFAULT);
	}
	/* TODO: we assume AF_INET here, change this when we support AF_UNIX */
	if (addr->sa_family != AF_INET && addr->sa_family != AF_UNSPEC) {
	warning("connecting to address family %i, but we only support AF_INET",
	(int)addr->sa_family);
	return syscallreturn_makeDoneErrno(EAFNOSUPPORT);
	} else if (!legacysocket_isFamilySupported(socket_desc, addr->sa_family)) {
	return syscallreturn_makeDoneErrno(EAFNOSUPPORT);
	}
	/* TODO: update for AF_UNIX */
	struct sockaddr_in* inet_addr = (struct sockaddr_in*)addr;
	sa_family_t family = inet_addr->sin_family;
	in_addr_t peerAddr = inet_addr->sin_addr.s_addr;
	in_port_t peerPort = inet_addr->sin_port;
	in_addr_t loopbackAddr = htonl(INADDR_LOOPBACK);
	if (peerAddr == htonl(INADDR_ANY)) {
	peerAddr = loopbackAddr;
	}
	/* make sure we will be able to route this later */
	if (peerAddr != loopbackAddr) {
	const Address* myAddress = host_getDefaultAddress(_syscallhandler_getHost(sys));
	const Address* peerAddress = worker_resolveIPToAddress(peerAddr);
	in_addr_t myAddr = htonl(address_toHostIP(myAddress));
	if (!peerAddress || !worker_isRoutable(myAddr, peerAddr)) {
	/* can't route it - there is no node with this address */
	gchar* peerAddressString = address_ipToNewString(peerAddr);
	warning("attempting to connect to address '%s:%u' for which no "
	"host exists",
	peerAddressString, ntohs(peerPort));
	g_free(peerAddressString);
	return syscallreturn_makeDoneErrno(ECONNREFUSED);
	}
	}
	if (!legacysocket_isBound(socket_desc)) {
	/* do an implicit bind to a random ephemeral port.
	* use default interface unless the remote peer is on loopback */
	in_addr_t bindAddr = (loopbackAddr == peerAddr)
	? loopbackAddr
	: host_getDefaultIP(_syscallhandler_getHost(sys));
	errcode = _syscallhandler_bindHelper(
	sys, socket_desc, bindAddr, 0, peerAddr, peerPort);
	if (errcode < 0) {
	return syscallreturn_makeDoneErrno(-errcode);
	}
	} else {
	legacysocket_setPeerName(socket_desc, peerAddr, peerPort);
	}
	/* Now we are ready to connect. */
	errcode = legacysocket_connectToPeer(
	socket_desc, _syscallhandler_getHost(sys), peerAddr, peerPort, family);
	LegacyFile* desc = (LegacyFile*)socket_desc;
	if (legacyfile_getType(desc) == DT_TCPSOCKET && !(legacyfile_getFlags(desc) & O_NONBLOCK)) {
	/* This is a blocking connect call. */
	if (errcode == -EINPROGRESS) {
	/* This is the first time we ever called connect, and so we
	* need to wait for the 3-way handshake to complete.
	* We will wait indefinitely for a success or failure. */
	Trigger trigger = (Trigger){.type = TRIGGER_DESCRIPTOR,
	.object = desc,
	.status = STATUS_FILE_ACTIVE | STATUS_FILE_WRITABLE};
	return syscallreturn_makeBlocked(
	syscallcondition_new(trigger), legacyfile_supportsSaRestart(desc));
	} else if (_syscallhandler_wasBlocked(sys) && errcode == -EISCONN) {
	/* It was EINPROGRESS, but is now a successful blocking connect. */
	errcode = 0;
	}
	}
	/* Make sure we return valid error codes for connect. */
	if (errcode == -ECONNRESET || errcode == -ENOTCONN) {
	errcode = -EISCONN;
	}
	/* -EALREADY is well defined in man page, but Linux returns -EINPROGRESS. */
	else if (errcode == -EALREADY) {
	errcode = -EINPROGRESS;
	}
	/* Return 0, -EINPROGRESS, etc. now. */
	return syscallreturn_makeDoneI64(errcode);
	}