Cellular: Stack type based on assigned IP addresses versions

Author: Mirela Chirica

UNITTESTS/stubs/CellularUtil_stub.cpp

@@ -51,9 +51,9 @@ uint16_t char_str_to_hex(const char *str, uint16_t len, char *buf, bool omit_lea
     return CellularUtil_stub::uint16_value;
 }
 
-void convert_ipv6(char *ip)
+nsapi_version_t convert_ipv6(char *ip)
 {
-
+    return NSAPI_UNSPEC;
 }
 
 char *find_dot_number(char *str, int dot_number)

features/cellular/framework/AT/AT_CellularStack.cpp

@@ -59,27 +59,43 @@ const char *AT_CellularStack::get_ip_address()
 {
     _at.lock();
 
+    bool ipv4 = false, ipv6 = false;
+
     _at.cmd_start_stop("+CGPADDR", "=", "%d", _cid);
     _at.resp_start("+CGPADDR:");
 
-    int len = -1;
     if (_at.info_resp()) {
         _at.skip_param();
 
-        len = _at.read_string(_ip, PDP_IPV6_SIZE);
-
-        if (len != -1 && _stack_type != IPV4_STACK) {
-            // in case stack type is not IPV4 only, try to look also for IPV6 address
-            (void)_at.read_string(_ip, PDP_IPV6_SIZE);
+        if (_at.read_string(_ip, PDP_IPV6_SIZE) != -1) {
+            convert_ipv6(_ip);
+            SocketAddress address;
+            address.set_ip_address(_ip);
+
+            ipv4 = (address.get_ip_version() == NSAPI_IPv4);
+            ipv6 = (address.get_ip_version() == NSAPI_IPv6);
+
+            // Try to look for second address ONLY if modem has support for dual stack(can handle both IPv4 and IPv6 simultaneously).
+            // Otherwise assumption is that second address is not reliable, even if network provides one.
+            if ((get_property(PROPERTY_IPV4V6_PDP_TYPE) && (_at.read_string(_ip, PDP_IPV6_SIZE) != -1))) {
+                convert_ipv6(_ip);
+                address.set_ip_address(_ip);
+                ipv6 = (address.get_ip_version() == NSAPI_IPv6);
+            }
         }
     }
     _at.resp_stop();
     _at.unlock();
 
-    // we have at least IPV4 address
-    convert_ipv6(_ip);
+    if (ipv4 && ipv6) {
+        _stack_type = IPV4V6_STACK;
+    } else if (ipv4) {
+        _stack_type = IPV4_STACK;
+    } else if (ipv6) {
+        _stack_type = IPV6_STACK;
+    }
 
-    return len != -1 ? _ip : NULL;
+    return (ipv4 || ipv6) ? _ip : NULL;
 }
 
 nsapi_error_t AT_CellularStack::socket_stack_init()

features/cellular/framework/AT/AT_CellularStack.h

@@ -203,7 +203,7 @@ class AT_CellularStack : public NetworkStack, public AT_CellularBase {
     // PDP context id
     int _cid;
 
-    // stack type from PDP context
+    // stack type - initialised as PDP type and set accordingly after CGPADDR checked
     nsapi_ip_stack_t _stack_type;
 
 private:

features/cellular/framework/common/CellularUtil.cpp

@@ -28,10 +28,10 @@
 using namespace mbed;
 namespace mbed_cellular_util {
 
-void convert_ipv6(char *ip)
+nsapi_version_t convert_ipv6(char *ip)
 {
     if (!ip) {
-        return;
+        return NSAPI_UNSPEC;
     }
 
     int len = strlen(ip);
@@ -49,7 +49,11 @@ void convert_ipv6(char *ip)
 
     // more that 3 periods mean that it was ipv6 but in format of a1.a2.a3.a4.a5.a6.a7.a8.a9.a10.a11.a12.a13.a14.a15.a16
     // we need to convert it to hexadecimal format separated with colons
-    if (pos > 3) {
+    if (pos == 3) {
+
+        return NSAPI_IPv4;
+
+    } else if (pos > 3) {
         pos = 0;
         int ip_pos = 0;
         char b;
@@ -74,7 +78,11 @@ void convert_ipv6(char *ip)
                 ip[pos] = '\0';
             }
         }
+
+        return NSAPI_IPv6;
     }
+
+    return NSAPI_UNSPEC;
 }
 
 // For example "32.1.13.184.0.0.205.48.0.0.0.0.0.0.0.0"

features/cellular/framework/common/CellularUtil.h

@@ -48,8 +48,9 @@ static const char hex_values[] = "0123456789ABCDEF";
  *  where ax are in decimal format. In this case, function converts decimals to hex with separated with colons.
  *
  *  @param ip       IP address that can be IPv4 or IPv6 in different formats from AT command +CGPADDR. Converted result uses same buffer.
+ *  @return         IP version of the address or NSAPI_UNSPEC if param ip empty or if IPv4 or IPv6 version could not be concluded.
  */
-void convert_ipv6(char *ip);
+nsapi_version_t convert_ipv6(char *ip);
 
 /** Separates IP addresses from the given 'orig' string. 'orig' may contain zero, one or two IP addresses in various formats.
  *  See AT command +CGPIAF from 3GPP TS 27.007 for details. Does also needed conversions for IPv6 addresses.