Update getSubscriberNo and getCCID. Make them memory-safe.

Author: PaulZC

src/SparkFun_u-blox_SARA-R5_Arduino_Library.cpp

@@ -1028,7 +1028,8 @@ String SARA_R5::getIMSI(void)
 String SARA_R5::getCCID(void)
 {
   char *response;
-  char ccidResponse[21] = {0x00}; // E.g. +CCID: 8939107900010087330
+  const int maxTextLen = 21;
+  char ccidResponse[maxTextLen] = {0x00}; // E.g. +CCID: 8939107900010087330
   SARA_R5_error_t err;
 
   response = sara_r5_calloc_char(minimumResponseAllocation);
@@ -1042,9 +1043,12 @@ String SARA_R5::getCCID(void)
     {
       searchPtr += strlen("\r\n+CCID:"); // Move searchPtr to first character - probably a space
       while (*searchPtr == ' ') searchPtr++; // skip spaces
-      if (sscanf(searchPtr, "%s", ccidResponse) != 1)
+      if (strlen(searchPtr) < maxTextLen) // Check we have enough space to hold the text
       {
-        memset(ccidResponse, 0, 21);
+        if (sscanf(searchPtr, "%s", ccidResponse) != 1)
+        {
+          ccidResponse[0] = 0;
+        }
       }
     }
   }
@@ -1055,7 +1059,8 @@ String SARA_R5::getCCID(void)
 String SARA_R5::getSubscriberNo(void)
 {
   char *response;
-  char idResponse[128] = {0x00}; // E.g. +CNUM: "ABCD . AAA","123456789012",129
+  const int maxTextLen = 128;
+  char idResponse[maxTextLen] = {0x00}; // E.g. +CNUM: "ABCD . AAA","123456789012",129
   SARA_R5_error_t err;
 
   response = sara_r5_calloc_char(minimumResponseAllocation);
@@ -1064,9 +1069,18 @@ String SARA_R5::getSubscriberNo(void)
                                 SARA_R5_RESPONSE_OK_OR_ERROR, response, SARA_R5_10_SEC_TIMEOUT);
   if (err == SARA_R5_ERROR_SUCCESS)
   {
-    if (sscanf(response, "\r\n+CNUM: %s", idResponse) != 1)
+    char *searchPtr = strstr(response, "\r\n+CNUM:");
+    if (searchPtr != nullptr)
     {
-      memset(idResponse, 0, 128);
+      searchPtr += strlen("\r\n+CNUM:"); // Move searchPtr to first character - probably a space
+      while (*searchPtr == ' ') searchPtr++; // skip spaces
+      if (strlen(searchPtr) < maxTextLen) // Check we have enough space to hold the text
+      {
+        if (sscanf(searchPtr, "%s", idResponse) != 1)
+        {
+          idResponse[0] = 0;
+        }
+      }
     }
   }
   free(response);