using strtoul instead of atoi
using strtoul instead of atoi

refer to https://www.securecoding.cert.org/confluence/x/qoAyAQ
StalderT/open62541,AGIsmail/open62541,jpfr/open62541,bostjanv/open62541,StalderT/open62541,JGrothoff/open62541,jpfr/open62541,open62541/open62541,JGrothoff/open62541,StalderT/open62541,jpfr/open62541,StalderT/open62541,JGrothoff/open62541,open62541/open62541,open62541/open62541,AGIsmail/open62541,open62541/open62541,jpfr/open62541,JGrothoff/open62541,bostjanv/open62541