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Dependents:   ublox-at-cellular-interface-ext

Fork of ublox-at-cellular-interface by u-blox

Revision:
0:7ccf0e7e8a83
Child:
1:bc228becc45d
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/UbloxATCellularInterface.cpp	Mon Jun 12 21:32:21 2017 +0000
@@ -0,0 +1,1208 @@
+/* Copyright (c) 2017 ublox Limited
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "UbloxATCellularInterface.h"
+#include "mbed_poll.h"
+#include "nsapi.h"
+#include "APN_db.h"
+#ifdef FEATURE_COMMON_PAL
+#include "mbed_trace.h"
+#define TRACE_GROUP "UACI"
+#else
+#define tr_debug(format, ...) debug(format, ## __VA_ARGS__)
+#define tr_info(format, ...)  debug(format, ## __VA_ARGS__)
+#define tr_warn(format, ...)  debug(format, ## __VA_ARGS__)
+#define tr_error(format, ...) debug(format, ## __VA_ARGS__)
+#endif
+
+/**********************************************************************
+ * PRIVATE METHODS
+ **********************************************************************/
+
+// Event thread for asynchronous received data handling.
+void UbloxATCellularInterface::handle_event(){
+    pollfh fhs;
+    int count;
+    int at_timeout;
+
+    fhs.fh = _fh;
+    fhs.events = POLLIN;
+
+    while (true) {
+        count = poll(&fhs, 1, 1000);
+        if (count > 0 && (fhs.revents & POLLIN)) {
+            LOCK();
+            at_timeout = _at_timeout;
+            at_set_timeout(10); // Avoid blocking but also make sure we don't
+                                // time out if we get ahead of the serial port
+            _at->debug_on(false); // Debug here screws with the test output
+            // Let the URCs run
+            _at->recv(UNNATURAL_STRING);
+            _at->debug_on(_debug_trace_on);
+            at_set_timeout(at_timeout);
+            UNLOCK();
+        }
+    }
+}
+
+// Find or create a socket from the list.
+UbloxATCellularInterface::SockCtrl * UbloxATCellularInterface::find_socket(int modem_handle)
+{
+    UbloxATCellularInterface::SockCtrl *socket = NULL;
+
+    for (unsigned int x = 0; (socket == NULL) && (x < sizeof(_sockets) / sizeof(_sockets[0])); x++) {
+        if (_sockets[x].modem_handle == modem_handle) {
+            socket = &(_sockets[x]);
+        }
+    }
+
+    return socket;
+}
+
+// Clear out the storage for a socket
+void UbloxATCellularInterface::clear_socket(UbloxATCellularInterface::SockCtrl * socket)
+{
+    if (socket != NULL) {
+        socket->modem_handle = SOCKET_UNUSED;
+        socket->pending     = 0;
+        socket->callback    = NULL;
+        socket->data        = NULL;
+    }
+}
+
+// Check that a socket pointer is valid
+bool UbloxATCellularInterface::check_socket(SockCtrl * socket)
+{
+    bool success = false;
+
+    if (socket != NULL) {
+        for (unsigned int x = 0; !success && (x < sizeof(_sockets) / sizeof(_sockets[0])); x++) {
+            if (socket == &(_sockets[x])) {
+                success = true;
+            }
+        }
+    }
+
+    return success;
+}
+
+// Convert nsapi_security_t to the modem security numbers
+int UbloxATCellularInterface::nsapi_security_to_modem_security(nsapi_security_t nsapi_security)
+{
+    int modem_security = 3;
+
+    switch (nsapi_security)
+    {
+        case NSAPI_SECURITY_NONE:
+            modem_security = 0;
+            break;
+        case NSAPI_SECURITY_PAP:
+            modem_security = 1;
+            break;
+        case NSAPI_SECURITY_CHAP:
+            modem_security = 2;
+            break;
+        case NSAPI_SECURITY_UNKNOWN:
+            modem_security = 3;
+            break;
+        default:
+            modem_security = 3;
+            break;
+    }
+
+    return modem_security;
+}
+
+// Callback for Socket Read URC.
+void UbloxATCellularInterface::UUSORD_URC()
+{
+    int a;
+    int b;
+    char buf[32];
+    SockCtrl *socket;
+
+    // Note: not calling _at->recv() from here as we're
+    // already in an _at->recv()
+    // +UUSORD: <socket>,<length>
+    if (read_at_to_char(buf, sizeof (buf), '\n') > 0) {
+        if (sscanf(buf, ": %d,%d", &a, &b) == 2) {
+            socket = find_socket(a);
+            if (socket != NULL) {
+                socket->pending = b;
+                // No debug prints here as they can affect timing
+                // and cause data loss in UARTSerial
+                if (socket->callback != NULL) {
+                    socket->callback(socket->data);
+                }
+            }
+        }
+    }
+}
+
+// Callback for Socket Read From URC.
+void UbloxATCellularInterface::UUSORF_URC()
+{
+    int a;
+    int b;
+    char buf[32];
+    SockCtrl *socket;
+
+    // Note: not calling _at->recv() from here as we're
+    // already in an _at->recv()
+    // +UUSORF: <socket>,<length>
+    if (read_at_to_char(buf, sizeof (buf), '\n') > 0) {
+        if (sscanf(buf, ": %d,%d", &a, &b) == 2) {
+            socket = find_socket(a);
+            if (socket != NULL) {
+                socket->pending = b;
+                // No debug prints here as they can affect timing
+                // and cause data loss in UARTSerial
+                if (socket->callback != NULL) {
+                    socket->callback(socket->data);
+                }
+            }
+        }
+    }
+}
+
+// Callback for Socket Close URC.
+void UbloxATCellularInterface::UUSOCL_URC()
+{
+    int a;
+    char buf[32];
+    SockCtrl *socket;
+
+    // Note: not calling _at->recv() from here as we're
+    // already in an _at->recv()
+    // +UUSOCL: <socket>
+    if (read_at_to_char(buf, sizeof (buf), '\n') > 0) {
+        if (sscanf(buf, ": %d", &a) == 1) {
+            socket = find_socket(a);
+            tr_debug("Socket 0x%08x: handle %d closed by remote host",
+                     (unsigned int) socket, a);
+            clear_socket(socket);
+        }
+    }
+}
+
+// Callback for UUPSDD.
+void UbloxATCellularInterface::UUPSDD_URC()
+{
+    int a;
+    char buf[32];
+    SockCtrl *socket;
+
+    // Note: not calling _at->recv() from here as we're
+    // already in an _at->recv()
+    // +UUPSDD: <socket>
+    if (read_at_to_char(buf, sizeof (buf), '\n') > 0) {
+        if (sscanf(buf, ": %d", &a) == 1) {
+            socket = find_socket(a);
+            tr_debug("Socket 0x%08x: handle %d connection lost",
+                     (unsigned int) socket, a);
+            clear_socket(socket);
+            if (_connection_status_cb) {
+                _connection_status_cb(NSAPI_ERROR_CONNECTION_LOST);
+            }
+        }
+    }
+}
+
+/**********************************************************************
+ * PROTECTED METHODS: GENERAL
+ **********************************************************************/
+
+// Get the next set of credentials, based on IMSI.
+void UbloxATCellularInterface::get_next_credentials(const char * config)
+{
+    if (config) {
+        _apn    = _APN_GET(config);
+        _uname  = _APN_GET(config);
+        _pwd    = _APN_GET(config);
+    }
+
+    _apn    = _apn     ?  _apn    : "";
+    _uname  = _uname   ?  _uname  : "";
+    _pwd    = _pwd     ?  _pwd    : "";
+}
+
+// Active a connection profile on board the modem.
+// Note: the AT interface should be locked before this is called.
+bool UbloxATCellularInterface::activate_profile(const char* apn,
+                                                const char* username,
+                                                const char* password,
+                                                nsapi_security_t auth)
+{
+    bool activated = false;
+    bool success = false;
+    int at_timeout = _at_timeout;
+    SocketAddress address;
+
+    // Set up the APN
+    if (*apn) {
+        success = _at->send("AT+UPSD=" PROFILE ",1,\"%s\"", apn) && _at->recv("OK");
+    }
+    if (success && *username) {
+        success = _at->send("AT+UPSD=" PROFILE ",2,\"%s\"", username) && _at->recv("OK");
+    }
+    if (success && *password) {
+        success = _at->send("AT+UPSD=" PROFILE ",3,\"%s\"", password) && _at->recv("OK");
+    }
+
+    if (success) {
+        // Set up dynamic IP address assignment.
+        success = _at->send("AT+UPSD=" PROFILE ",7,\"0.0.0.0\"") && _at->recv("OK");
+        // Set up the authentication protocol
+        // 0 = none
+        // 1 = PAP (Password Authentication Protocol)
+        // 2 = CHAP (Challenge Handshake Authentication Protocol)
+        for (int protocol = nsapi_security_to_modem_security(NSAPI_SECURITY_NONE);
+             success && (protocol <= nsapi_security_to_modem_security(NSAPI_SECURITY_CHAP)); protocol++) {
+            if ((_auth == NSAPI_SECURITY_UNKNOWN) || (nsapi_security_to_modem_security(_auth) == protocol)) {
+                if (_at->send("AT+UPSD=" PROFILE ",6,%d", protocol) && _at->recv("OK")) {
+                    // Activate, waiting 30 seconds for the connection to be made
+                    at_set_timeout(30000);
+                    activated = _at->send("AT+UPSDA=" PROFILE ",3") && _at->recv("OK");
+                    at_set_timeout(at_timeout);
+                }
+            }
+        }
+    }
+
+    return activated;
+}
+
+// Activate a profile by reusing an external PDP context.
+// Note: the AT interface should be locked before this is called.
+bool UbloxATCellularInterface::activate_profile_reuse_external(void)
+{
+    bool success = false;
+    int cid = -1;
+    char ip[NSAPI_IP_SIZE];
+    SocketAddress address;
+    int t;
+    int at_timeout = _at_timeout;
+
+    //+CGDCONT: <cid>,"IP","<apn name>","<ip adr>",0,0,0,0,0,0
+    if (_at->send("AT+CGDCONT?")) {
+        if (_at->recv("+CGDCONT: %d,\"IP\",\"%*[^\"]\",\"%" u_stringify(NSAPI_IP_SIZE) "[^\"]\",%*d,%*d,%*d,%*d,%*d,%*d",
+                      &t, ip) &&
+            _at->recv("OK")) {
+            // Check if the IP address is valid
+            if (address.set_ip_address(ip)) {
+                cid = t;
+            }
+        }
+    }
+
+    // If a context has been found, use it
+    if ((cid != -1) && (_at->send("AT+UPSD=" PROFILE ",100,%d", cid) && _at->recv("OK"))) {
+        // Activate, waiting 30 seconds for the connection to be made
+        at_set_timeout(30000);
+        success = _at->send("AT+UPSDA=" PROFILE ",3") && _at->recv("OK");
+        at_set_timeout(at_timeout);
+    }
+
+    return success;
+}
+
+// Activate a profile by context ID.
+// Note: the AT interface should be locked before this is called.
+bool UbloxATCellularInterface::activate_profile_by_cid(int cid,
+                                                       const char* apn,
+                                                       const char* username,
+                                                       const char* password,
+                                                       nsapi_security_t auth)
+{
+    bool success = false;
+    int at_timeout = _at_timeout;
+
+    if (_at->send("AT+CGDCONT=%d,\"IP\",\"%s\"", cid, apn) && _at->recv("OK") &&
+        _at->send("AT+UAUTHREQ=%d,%d,\"%s\",\"%s\"", cid, nsapi_security_to_modem_security(auth),
+                  username, password) && _at->recv("OK") &&
+        _at->send("AT+UPSD=" PROFILE ",100,%d", cid) && _at->recv("OK")) {
+
+        // Wait 30 seconds for the connection to be made
+        at_set_timeout(30000);
+        // Activate the protocol
+        success = _at->send("AT+UPSDA=" PROFILE ",3") && _at->recv("OK");
+        at_set_timeout(at_timeout);
+    }
+
+    return success;
+}
+
+// Connect the on board IP stack of the modem.
+bool UbloxATCellularInterface::connect_modem_stack()
+{
+    bool success = false;
+    int active = 0;
+    const char * config = NULL;
+    LOCK();
+
+    // Check the profile
+    if (_at->send("AT+UPSND=" PROFILE ",8") && _at->recv("+UPSND: %*d,%*d,%d\n", &active) &&
+        _at->recv("OK")) {
+        if (active == 0) {
+            // If the caller hasn't entered an APN, try to find it
+            if (_apn == NULL) {
+                config = apnconfig(_dev_info.imsi);
+            }
+
+            // Attempt to connect
+            do {
+                // Set up APN and IP protocol for PDP context
+                get_next_credentials(config);
+                _auth = (*_uname && *_pwd) ? _auth : NSAPI_SECURITY_NONE;
+                if ((_dev_info.dev != DEV_TOBY_L2) && (_dev_info.dev != DEV_MPCI_L2)) {
+                    success = activate_profile(_apn, _uname, _pwd, _auth);
+                } else {
+                    success = activate_profile_reuse_external();
+                    if (success) {
+                        tr_debug("Reusing external context");
+                    } else {
+                        success = activate_profile_by_cid(1, _apn, _uname, _pwd, _auth);
+                    }
+                }
+            } while (!success && config && *config);
+        } else {
+            // If the profile is already active, we're good
+            success = true;
+        }
+    }
+
+    if (!success) {
+        tr_error("Failed to connect, check your APN/username/password");
+    }
+
+    UNLOCK();
+    return success;
+}
+
+// Disconnect the on board IP stack of the modem.
+bool UbloxATCellularInterface::disconnect_modem_stack()
+{
+    bool success = false;
+    LOCK();
+
+    if (get_ip_address() != NULL) {
+        if (_at->send("AT+UPSDA=" PROFILE ",4") && _at->recv("OK")) {
+            success = true;
+            if (_connection_status_cb) {
+                _connection_status_cb(NSAPI_ERROR_CONNECTION_LOST);
+            }
+        }
+    }
+
+    UNLOCK();
+    return success;
+}
+
+/**********************************************************************
+ * PROTECTED METHODS: NETWORK INTERFACE and SOCKETS
+ **********************************************************************/
+
+// Gain access to us.
+NetworkStack *UbloxATCellularInterface::get_stack()
+{
+    return this;
+}
+
+// Create a socket.
+nsapi_error_t UbloxATCellularInterface::socket_open(nsapi_socket_t *handle,
+                                                    nsapi_protocol_t proto)
+{
+    nsapi_error_t nsapi_error = NSAPI_ERROR_DEVICE_ERROR;
+    bool success = false;
+    int modem_handle;
+    SockCtrl *socket;
+    LOCK();
+
+    // Find a free socket
+    socket = find_socket();
+    tr_debug("socket_open(%d)", proto);
+
+    if (socket != NULL) {
+        if (proto == NSAPI_UDP) {
+            success = _at->send("AT+USOCR=17");
+        } else if (proto == NSAPI_TCP) {
+            success = _at->send("AT+USOCR=6");
+        } else  {
+            nsapi_error = NSAPI_ERROR_UNSUPPORTED;
+        }
+
+        if (success) {
+            nsapi_error = NSAPI_ERROR_NO_SOCKET;
+            if (_at->recv("+USOCR: %d\n", &modem_handle) && (modem_handle != SOCKET_UNUSED) &&
+                _at->recv("OK")) {
+                tr_debug("Socket 0x%8x: handle %d was created", (unsigned int) socket, modem_handle);
+                clear_socket(socket);
+                socket->modem_handle         = modem_handle;
+                *handle = (nsapi_socket_t) socket;
+                nsapi_error = NSAPI_ERROR_OK;
+            }
+        }
+    } else {
+        nsapi_error = NSAPI_ERROR_NO_MEMORY;
+    }
+
+    UNLOCK();
+    return nsapi_error;
+}
+
+// Close a socket.
+nsapi_error_t UbloxATCellularInterface::socket_close(nsapi_socket_t handle)
+{
+    nsapi_error_t nsapi_error = NSAPI_ERROR_DEVICE_ERROR;
+    SockCtrl *socket = (SockCtrl *) handle;
+    LOCK();
+
+    tr_debug("socket_close(0x%08x)", (unsigned int) handle);
+
+    MBED_ASSERT (check_socket(socket));
+
+    if (_at->send("AT+USOCL=%d", socket->modem_handle) &&
+        _at->recv("OK")) {
+        clear_socket(socket);
+        nsapi_error = NSAPI_ERROR_OK;
+    }
+
+    UNLOCK();
+    return nsapi_error;
+}
+
+// Bind a local port to a socket.
+nsapi_error_t UbloxATCellularInterface::socket_bind(nsapi_socket_t handle,
+                                                    const SocketAddress &address)
+{
+    nsapi_error_t nsapi_error = NSAPI_ERROR_NO_SOCKET;
+    int proto;
+    int modem_handle;
+    SockCtrl savedSocket;
+    SockCtrl *socket = (SockCtrl *) handle;
+    LOCK();
+
+    tr_debug("socket_bind(0x%08x, :%d)", (unsigned int) handle, address.get_port());
+
+    MBED_ASSERT (check_socket(socket));
+
+    // Query the socket type
+    if (_at->send("AT+USOCTL=%d,0", socket->modem_handle) &&
+        _at->recv("+USOCTL: %*d,0,%d\n", &proto) &&
+        _at->recv("OK")) {
+        savedSocket = *socket;
+        nsapi_error = NSAPI_ERROR_DEVICE_ERROR;
+        // Now close the socket and re-open it with the binding given
+        if (_at->send("AT+USOCL=%d", socket->modem_handle) &&
+            _at->recv("OK")) {
+            clear_socket(socket);
+            nsapi_error = NSAPI_ERROR_CONNECTION_LOST;
+            if (_at->send("AT+USOCR=%d,%d", proto, address.get_port()) &&
+                _at->recv("+USOCR: %d\n", &modem_handle) && (modem_handle != SOCKET_UNUSED) &&
+                _at->recv("OK")) {
+                *socket = savedSocket;
+                nsapi_error = NSAPI_ERROR_OK;
+            }
+        }
+    }
+
+    UNLOCK();
+    return nsapi_error;
+}
+
+// Connect to a socket
+nsapi_error_t UbloxATCellularInterface::socket_connect(nsapi_socket_t handle,
+                                                       const SocketAddress &address)
+{
+    nsapi_error_t nsapi_error = NSAPI_ERROR_DEVICE_ERROR;
+    SockCtrl *socket = (SockCtrl *) handle;
+    LOCK();
+
+    tr_debug("socket_connect(0x%08x, %s(:%d))", (unsigned int) handle,
+             address.get_ip_address(), address.get_port());
+
+    MBED_ASSERT (check_socket(socket));
+
+    if (_at->send("AT+USOCO=%d,\"%s\",%d", socket->modem_handle,
+                  address.get_ip_address(), address.get_port()) &&
+        _at->recv("OK")) {
+        nsapi_error = NSAPI_ERROR_OK;
+    }
+
+    UNLOCK();
+    return nsapi_error;
+}
+
+// Send to a socket.
+nsapi_size_or_error_t UbloxATCellularInterface::socket_send(nsapi_socket_t handle,
+                                                            const void *data,
+                                                            nsapi_size_t size)
+{
+    nsapi_size_or_error_t nsapi_error_size = NSAPI_ERROR_DEVICE_ERROR;
+    bool success = true;
+    const char *buf = (const char *) data;
+    nsapi_size_t blk = MAX_WRITE_SIZE;
+    nsapi_size_t count = size;
+    SockCtrl *socket = (SockCtrl *) handle;
+
+    tr_debug("socket_send(0x%08x, 0x%08x, %d)", (unsigned int) handle, (unsigned int) data, size);
+
+    MBED_ASSERT (check_socket(socket));
+
+    while ((count > 0) && success) {
+        if (count < blk) {
+            blk = count;
+        }
+        LOCK();
+
+        if (_at->send("AT+USOWR=%d,%d", socket->modem_handle, blk) && _at->recv("@")) {
+            wait_ms(50);
+            if ((_at->write(buf, blk) < (int) blk) ||
+                 !_at->recv("OK")) {
+                success = false;
+            }
+        } else {
+            success = false;
+        }
+
+        UNLOCK();
+        buf += blk;
+        count -= blk;
+    }
+
+    if (success) {
+        nsapi_error_size = size - count;
+        if (_debug_trace_on) {
+            tr_debug("socket_send: %d \"%*.*s\"", size, size, size, (char *) data);
+        }
+    }
+
+    return nsapi_error_size;
+}
+
+// Send to an IP address.
+nsapi_size_or_error_t UbloxATCellularInterface::socket_sendto(nsapi_socket_t handle,
+                                                              const SocketAddress &address,
+                                                              const void *data,
+                                                              nsapi_size_t size)
+{
+    nsapi_size_or_error_t nsapi_error_size = NSAPI_ERROR_DEVICE_ERROR;
+    bool success = true;
+    const char *buf = (const char *) data;
+    nsapi_size_t blk = MAX_WRITE_SIZE;
+    nsapi_size_t count = size;
+    SockCtrl *socket = (SockCtrl *) handle;
+
+    tr_debug("socket_sendto(0x%8x, %s(:%d), 0x%08x, %d)", (unsigned int) handle,
+             address.get_ip_address(), address.get_port(), (unsigned int) data, size);
+
+    MBED_ASSERT (check_socket(socket));
+
+    if (size > MAX_WRITE_SIZE) {
+        tr_warn("WARNING: packet length %d is too big for one UDP packet (max %d), will be fragmented.", size, MAX_WRITE_SIZE);
+    }
+
+    while ((count > 0) && success) {
+        if (count < blk) {
+            blk = count;
+        }
+        LOCK();
+
+        if (_at->send("AT+USOST=%d,\"%s\",%d,%d", socket->modem_handle,
+                      address.get_ip_address(), address.get_port(), blk) &&
+            _at->recv("@")) {
+            wait_ms(50);
+            if ((_at->write(buf, blk) >= (int) blk) &&
+                 _at->recv("OK")) {
+            } else {
+                success = false;
+            }
+        } else {
+            success = false;
+        }
+
+        UNLOCK();
+        buf += blk;
+        count -= blk;
+    }
+
+    if (success) {
+        nsapi_error_size = size - count;
+        if (_debug_trace_on) {
+            tr_debug("socket_sendto: %d \"%*.*s\"", size, size, size, (char *) data);
+        }
+    }
+
+    return nsapi_error_size;
+}
+
+// Receive from a socket, TCP style.
+nsapi_size_or_error_t UbloxATCellularInterface::socket_recv(nsapi_socket_t handle,
+                                                            void *data,
+                                                            nsapi_size_t size)
+{
+    nsapi_size_or_error_t nsapi_error_size = NSAPI_ERROR_DEVICE_ERROR;
+    bool success = true;
+    char *buf = (char *) data;
+    nsapi_size_t read_blk;
+    nsapi_size_t count = 0;
+    unsigned int usord_sz;
+    int read_sz;
+    Timer timer;
+    SockCtrl *socket = (SockCtrl *) handle;
+    int at_timeout;
+
+    tr_debug("socket_recv(0x%08x, 0x%08x, %d)",
+             (unsigned int) handle, (unsigned int) data, size);
+
+    MBED_ASSERT (check_socket(socket));
+
+    timer.start();
+
+    while (success && (size > 0)) {
+        LOCK();
+        at_timeout = _at_timeout;
+        at_set_timeout(1000);
+
+        read_blk = MAX_READ_SIZE;
+        if (read_blk > size) {
+            read_blk = size;
+        }
+        if (socket->pending > 0) {
+            tr_debug("Socket 0x%08x: modem handle %d has %d byte(s) pending",
+                     (unsigned int) socket, socket->modem_handle, socket->pending);
+            _at->debug_on(false); // ABSOLUTELY no time for debug here if you want to
+                                  // be able to read packets of any size without
+                                  // losing characters in UARTSerial
+            if (_at->send("AT+USORD=%d,%d", socket->modem_handle, read_blk) &&
+                _at->recv("+USORD: %*d,%d,\"", &usord_sz)) {
+                socket->pending -= usord_sz; // Must use what +USORD returns here as it
+                                             // may be less than we asked for
+                // Note: insert no debug between _at->recv() and _at->read(), no time...
+                if (usord_sz > size) {
+                    usord_sz = size;
+                }
+                read_sz = _at->read(buf, usord_sz);
+                if (read_sz > 0) {
+                    tr_debug("...read %d byte(s) from modem handle %d...", read_sz,
+                             socket->modem_handle);
+                    if (_debug_trace_on) {
+                        tr_debug("Read returned %d,  |%*.*s|", read_sz, read_sz, read_sz, buf);
+                    }
+                    count += read_sz;
+                    buf += read_sz;
+                    size -= read_sz;
+                } else {
+                    // read() should not fail
+                    success = false;
+                }
+                tr_debug("Socket 0x%08x: modem handle %d now has only %d byte(s) pending",
+                         (unsigned int) socket, socket->modem_handle, socket->pending);
+                // Wait for the "OK" before continuing
+                _at->recv("OK");
+            } else {
+                // Should never fail to do _at->send()/_at->recv()
+                success = false;
+            }
+            _at->debug_on(_debug_trace_on);
+        } else if (timer.read_ms() < SOCKET_TIMEOUT) {
+            // Wait for URCs
+            _at->recv(UNNATURAL_STRING);
+        } else {
+            if (count == 0) {
+                // Timeout with nothing received
+                nsapi_error_size = NSAPI_ERROR_WOULD_BLOCK;
+                success = false;
+            }
+            size = 0; // This simply to cause an exit
+        }
+
+        at_set_timeout(at_timeout);
+        UNLOCK();
+    }
+    timer.stop();
+
+    if (success) {
+        nsapi_error_size = count;
+    }
+
+    if (_debug_trace_on) {
+        tr_debug("socket_recv: %d \"%*.*s\"", count, count, count, buf - count);
+    } else {
+        tr_debug("socket_recv: received %d byte(s)", count);
+    }
+
+    return nsapi_error_size;
+}
+
+// Receive a packet over a UDP socket.
+nsapi_size_or_error_t UbloxATCellularInterface::socket_recvfrom(nsapi_socket_t handle,
+                                                                SocketAddress *address,
+                                                                void *data,
+                                                                nsapi_size_t size)
+{
+    nsapi_size_or_error_t nsapi_error_size = NSAPI_ERROR_DEVICE_ERROR;
+    bool success = true;
+    char *buf = (char *) data;
+    nsapi_size_t read_blk;
+    nsapi_size_t count = 0;
+    char ipAddress[NSAPI_IP_SIZE];
+    int port;
+    unsigned int usorf_sz;
+    int read_sz;
+    Timer timer;
+    SockCtrl *socket = (SockCtrl *) handle;
+    int at_timeout;
+
+    tr_debug("socket_recvfrom(0x%08x, 0x%08x, %d)",
+             (unsigned int) handle, (unsigned int) data, size);
+
+    MBED_ASSERT (check_socket(socket));
+
+    timer.start();
+
+    while (success && (size > 0)) {
+        LOCK();
+        at_timeout = _at_timeout;
+        at_set_timeout(1000);
+
+        read_blk = MAX_READ_SIZE;
+        if (read_blk > size) {
+            read_blk = size;
+        }
+        if (socket->pending > 0) {
+            tr_debug("Socket 0x%08x: modem handle %d has %d byte(s) pending",
+                     (unsigned int) socket, socket->modem_handle, socket->pending);
+            memset (ipAddress, 0, sizeof (ipAddress)); // Ensure terminator
+
+            // Note: the maximum length of UDP packet we can receive comes from
+            // fitting all of the following into one buffer:
+            //
+            // +USORF: xx,"max.len.ip.address.ipv4.or.ipv6",yyyyy,wwww,"the_data"\r\n
+            //
+            // where xx is the handle, max.len.ip.address.ipv4.or.ipv6 is NSAPI_IP_SIZE,
+            // yyyyy is the port number (max 65536), wwww is the length of the data and
+            // the_data is binary data. I make that 29 + 48 + len(the_data),
+            // so the overhead is 77 bytes.
+
+            _at->debug_on(false); // ABSOLUTELY no time for debug here if you want to
+                                  // be able to read packets of any size without
+                                  // losing characters in UARTSerial
+            if (_at->send("AT+USORF=%d,%d", socket->modem_handle, read_blk) &&
+                _at->recv("+USORF: %*d,\"%" u_stringify(NSAPI_IP_SIZE) "[^\"]\",%d,%d,\"",
+                          ipAddress, &port, &usorf_sz)) {
+                socket->pending -= usorf_sz; // Must use what +USORF returns here as it
+                                             // may be less than we asked for
+                // Note: insert no debug between _at->recv() and _at->read(), no time...
+                if (usorf_sz > size) {
+                    usorf_sz = size;
+                }
+                read_sz = _at->read(buf, usorf_sz);
+                if (read_sz > 0) {
+                    address->set_ip_address(ipAddress);
+                    address->set_port(port);
+                    tr_debug("...read %d byte(s) from modem handle %d...", read_sz,
+                             socket->modem_handle);
+                    if (_debug_trace_on) {
+                        tr_debug("Read returned %d,  |%*.*s|", read_sz, read_sz, read_sz, buf);
+                    }
+                    count += read_sz;
+                    buf += read_sz;
+                    size -= read_sz;
+                    if ((usorf_sz < read_blk) || (usorf_sz == MAX_READ_SIZE)) {
+                        size = 0; // If we've received less than we asked for, or
+                                  // the max size, then a whole UDP packet has arrived and
+                                  // this means DONE.
+                    }
+                } else {
+                    // read() should not fail
+                    success = false;
+                }
+                tr_debug("Socket 0x%08x: modem handle %d now has only %d byte(s) pending",
+                         (unsigned int) socket, socket->modem_handle, socket->pending);
+                // Wait for the "OK" before continuing
+                _at->recv("OK");
+            } else {
+                // Should never fail to do _at->send()/_at->recv()
+                success = false;
+            }
+            _at->debug_on(_debug_trace_on);
+        } else if (timer.read_ms() < SOCKET_TIMEOUT) {
+            // Wait for URCs
+            _at->recv(UNNATURAL_STRING);
+        } else {
+            if (count == 0) {
+                // Timeout with nothing received
+                nsapi_error_size = NSAPI_ERROR_WOULD_BLOCK;
+                success = false;
+            }
+            size = 0; // This simply to cause an exit
+        }
+
+        at_set_timeout(at_timeout);
+        UNLOCK();
+    }
+    timer.stop();
+
+    if (success) {
+        nsapi_error_size = count;
+    }
+
+    if (_debug_trace_on) {
+        tr_debug("socket_recvfrom: %d \"%*.*s\"", count, count, count, buf - count);
+    } else {
+        tr_debug("socket_recvfrom: received %d byte(s)", count);
+    }
+
+    return nsapi_error_size;
+}
+
+// Attach an event callback to a socket, required for asynchronous
+// data reception
+void UbloxATCellularInterface::socket_attach(nsapi_socket_t handle,
+                                             void (*callback)(void *),
+                                             void *data)
+{
+    SockCtrl *socket = (SockCtrl *) handle;
+
+    MBED_ASSERT (check_socket(socket));
+
+    socket->callback = callback;
+    socket->data = data;
+}
+
+// Unsupported TCP server functions.
+nsapi_error_t UbloxATCellularInterface::socket_listen(nsapi_socket_t handle,
+                                                      int backlog)
+{
+    return NSAPI_ERROR_UNSUPPORTED;
+}
+nsapi_error_t UbloxATCellularInterface::socket_accept(nsapi_socket_t server,
+                                                      nsapi_socket_t *handle,
+                                                      SocketAddress *address)
+{
+    return NSAPI_ERROR_UNSUPPORTED;
+}
+
+// Unsupported option functions.
+nsapi_error_t UbloxATCellularInterface::setsockopt(nsapi_socket_t handle,
+                                                   int level, int optname,
+                                                   const void *optval,
+                                                   unsigned optlen)
+{
+    return NSAPI_ERROR_UNSUPPORTED;
+}
+nsapi_error_t UbloxATCellularInterface::getsockopt(nsapi_socket_t handle,
+                                                   int level, int optname,
+                                                   void *optval,
+                                                   unsigned *optlen)
+{
+    return NSAPI_ERROR_UNSUPPORTED;
+}
+
+/**********************************************************************
+ * PUBLIC METHODS
+ **********************************************************************/
+
+// Constructor.
+UbloxATCellularInterface::UbloxATCellularInterface(PinName tx,
+                                                   PinName rx,
+                                                   int baud,
+                                                   bool debug_on)
+{
+    _sim_pin_check_change_pending = false;
+    _sim_pin_check_change_pending_enabled_value = false;
+    _sim_pin_change_pending = false;
+    _sim_pin_change_pending_new_pin_value = NULL;
+    _apn = NULL;
+    _uname = NULL;
+    _pwd = NULL;
+    _connection_status_cb = NULL;
+
+    // Initialise sockets storage
+    memset(_sockets, 0, sizeof(_sockets));
+    for (unsigned int socket = 0; socket < sizeof(_sockets) / sizeof(_sockets[0]); socket++) {
+        _sockets[socket].modem_handle = SOCKET_UNUSED;
+        _sockets[socket].callback = NULL;
+        _sockets[socket].data = NULL;
+    }
+
+    // The authentication to use
+    _auth = NSAPI_SECURITY_UNKNOWN;
+
+    // Nullify the temporary IP address storage
+    _ip = NULL;
+
+    // Initialise the base class, which starts the AT parser
+    baseClassInit(tx, rx, baud, debug_on);
+
+    // Start the event handler thread for Rx data
+    event_thread.start(callback(this, &UbloxATCellularInterface::handle_event));
+
+    // URC handlers for sockets
+    _at->oob("+UUSORD", callback(this, &UbloxATCellularInterface::UUSORD_URC));
+    _at->oob("+UUSORF", callback(this, &UbloxATCellularInterface::UUSORF_URC));
+    _at->oob("+UUSOCL", callback(this, &UbloxATCellularInterface::UUSOCL_URC));
+    _at->oob("+UUPSDD", callback(this, &UbloxATCellularInterface::UUPSDD_URC));
+}
+
+// Destructor.
+UbloxATCellularInterface::~UbloxATCellularInterface()
+{
+    // Free _ip if it was ever allocated
+    free(_ip);
+}
+
+// Set the authentication scheme.
+void UbloxATCellularInterface::set_authentication(nsapi_security_t auth)
+{
+    _auth = auth;
+}
+
+// Set APN, user name and password.
+void  UbloxATCellularInterface::set_credentials(const char *apn,
+                                                const char *uname,
+                                                const char *pwd)
+{
+    _apn = apn;
+    _uname = uname;
+    _pwd = pwd;
+}
+
+// Set PIN.
+void UbloxATCellularInterface::set_sim_pin(const char *pin) {
+    set_pin(pin);
+}
+
+// Get the IP address of a host.
+nsapi_error_t UbloxATCellularInterface::gethostbyname(const char *host,
+                                                      SocketAddress *address,
+                                                      nsapi_version_t version)
+{
+    nsapi_error_t nsapi_error = NSAPI_ERROR_DEVICE_ERROR;
+    char ipAddress[NSAPI_IP_SIZE];
+
+    if (address->set_ip_address(host)) {
+        nsapi_error = NSAPI_ERROR_OK;
+    } else {
+        LOCK();
+        memset (ipAddress, 0, sizeof (ipAddress)); // Ensure terminator
+        if (_at->send("AT+UDNSRN=0,\"%s\"", host) &&
+            _at->recv("+UDNSRN: \"%" u_stringify(NSAPI_IP_SIZE) "[^\"]\"", ipAddress) &&
+            _at->recv("OK")) {
+            if (address->set_ip_address(ipAddress)) {
+                nsapi_error = NSAPI_ERROR_OK;
+            }
+        }
+        UNLOCK();
+    }
+
+    return nsapi_error;
+}
+
+// Make a cellular connection
+nsapi_error_t UbloxATCellularInterface::connect(const char *sim_pin,
+                                                const char *apn,
+                                                const char *uname,
+                                                const char *pwd)
+{
+    nsapi_error_t nsapi_error;
+
+    if (sim_pin != NULL) {
+        _pin = sim_pin;
+    }
+
+    if (apn != NULL) {
+        _apn = apn;
+    }
+
+    if ((uname != NULL) && (pwd != NULL)) {
+        _uname = uname;
+        _pwd = pwd;
+    } else {
+        _uname = NULL;
+        _pwd = NULL;
+    }
+
+    nsapi_error = connect();
+
+    return nsapi_error;
+}
+
+// Make a cellular connection using the IP stack on board the cellular modem
+nsapi_error_t UbloxATCellularInterface::connect()
+{
+    nsapi_error_t nsapi_error = NSAPI_ERROR_DEVICE_ERROR;
+    bool registered = false;
+
+    // Set up modem and then register with the network
+    if (init()) {
+        nsapi_error = NSAPI_ERROR_NO_CONNECTION;
+        // Perform any pending SIM actions
+        if (_sim_pin_check_change_pending) {
+            if (!sim_pin_check_enable(_sim_pin_check_change_pending_enabled_value)) {
+                nsapi_error = NSAPI_ERROR_AUTH_FAILURE;
+            }
+            _sim_pin_check_change_pending = false;
+        }
+        if (_sim_pin_change_pending) {
+            if (!change_sim_pin(_sim_pin_change_pending_new_pin_value)) {
+                nsapi_error = NSAPI_ERROR_AUTH_FAILURE;
+            }
+            _sim_pin_change_pending = false;
+        }
+
+        if (nsapi_error == NSAPI_ERROR_NO_CONNECTION) {
+            for (int retries = 0; !registered && (retries < 3); retries++) {
+                if (nwk_registration()) {
+                    registered = true;;
+                }
+            }
+        }
+    }
+
+    // Attempt to establish a connection
+    if (registered && connect_modem_stack()) {
+        nsapi_error = NSAPI_ERROR_OK;
+    }
+
+    return nsapi_error;
+}
+
+// User initiated disconnect.
+nsapi_error_t UbloxATCellularInterface::disconnect()
+{
+    nsapi_error_t nsapi_error = NSAPI_ERROR_DEVICE_ERROR;
+
+    if (disconnect_modem_stack() && nwk_deregistration()) {
+        nsapi_error = NSAPI_ERROR_OK;
+    }
+
+    return nsapi_error;
+}
+
+// Enable or disable SIM PIN check lock.
+nsapi_error_t UbloxATCellularInterface::set_sim_pin_check(bool set,
+                                                          bool immediate,
+                                                          const char *sim_pin)
+{
+    nsapi_error_t nsapi_error = NSAPI_ERROR_AUTH_FAILURE;
+
+    if (sim_pin != NULL) {
+        _pin = sim_pin;
+    }
+
+    if (immediate) {
+        if (init()) {
+            if (sim_pin_check_enable(set)) {
+                nsapi_error = NSAPI_ERROR_OK;
+            }
+        } else {
+            nsapi_error = NSAPI_ERROR_DEVICE_ERROR;
+        }
+    } else {
+        nsapi_error = NSAPI_ERROR_OK;
+        _sim_pin_check_change_pending = true;
+        _sim_pin_check_change_pending_enabled_value = set;
+    }
+
+    return nsapi_error;
+}
+
+// Change the PIN code for the SIM card.
+nsapi_error_t UbloxATCellularInterface::set_new_sim_pin(const char *new_pin,
+                                                        bool immediate,
+                                                        const char *old_pin)
+{
+    nsapi_error_t nsapi_error = NSAPI_ERROR_AUTH_FAILURE;
+
+    if (old_pin != NULL) {
+        _pin = old_pin;
+    }
+
+    if (immediate) {
+        if (init()) {
+            if (change_sim_pin(new_pin)) {
+                nsapi_error = NSAPI_ERROR_OK;
+            }
+        } else {
+            nsapi_error = NSAPI_ERROR_DEVICE_ERROR;
+        }
+    } else {
+        nsapi_error = NSAPI_ERROR_OK;
+        _sim_pin_change_pending = true;
+        _sim_pin_change_pending_new_pin_value = new_pin;
+    }
+
+    return nsapi_error;
+}
+
+// Determine if the connection is up.
+bool UbloxATCellularInterface::is_connected()
+{
+    return get_ip_address() != NULL;
+}
+
+// Get the IP address of the on-board modem IP stack.
+const char * UbloxATCellularInterface::get_ip_address()
+{
+    SocketAddress address;
+    LOCK();
+
+    if (_ip == NULL) {
+        // Temporary storage for an IP address string with terminator
+        _ip = (char *) malloc(NSAPI_IP_SIZE);
+    }
+
+    if (_ip != NULL) {
+        memset(_ip, 0, NSAPI_IP_SIZE); // Ensure a terminator
+        // +UPSND=<profile_id>,<param_tag>[,<dynamic_param_val>]
+        // If we get back a quoted "w.x.y.z" then we have an IP address,
+        // otherwise we don't.
+        if (!_at->send("AT+UPSND=" PROFILE ",0") ||
+            !_at->recv("+UPSND: " PROFILE ",0,\"%" u_stringify(NSAPI_IP_SIZE) "[^\"]\"", _ip) ||
+            !_at->recv("OK") ||
+            !address.set_ip_address(_ip) || // Return NULL if the address is not a valid one
+            !address) { // Return null if the address is zero
+            free (_ip);
+            _ip = NULL;
+        }
+    }
+
+    UNLOCK();
+    return _ip;
+}
+
+// Get the local network mask.
+const char *UbloxATCellularInterface::get_netmask()
+{
+    // Not implemented.
+    return NULL;
+}
+
+// Get the local gateways.
+const char *UbloxATCellularInterface::get_gateway()
+{
+    return get_ip_address();
+}
+
+// Callback in case the connection is lost.
+void UbloxATCellularInterface::connection_status_cb(Callback<void(nsapi_error_t)> cb)
+{
+    _connection_status_cb = cb;
+}
+
+// End of file
+