Is it possible in base R to replace multiple integers with corresponding strings like a dictionary?

Similar to this question: https://stackoverflow.com/questions/63173687/replace-multiple-values-in-r but: I would like to only use base R and I would like to replace integers, so the named vector solution adopted as below does not work:

testing <- data.frame(
  var1 = c(1, 6, 17)
)

# this is not possible
dict <- c(
  1 = 'ICMP', 
  6 = 'TCP', 
  17 = 'UDP', 
)

testing$var1 <- dict[testing$var1]

I know I can do

testing$var1[testing$var1 == 1] <- "ICMP"
testing$var1[testing$var1 == 6] <- "TCP"
testing$var1[testing$var1 == 17] <- "UDP"

but isn't there a more convenient way in base R?

# create named vector dict
dict <- c('ICMP', 'TCP', 'UDP')
names(dict) <- c(1,6,17)
# replace matching values
testing$var2 <- dict[as.character(testing$var1)]

#   var1 var2
# 1    1 ICMP
# 2    6  TCP
# 3   17  UDP

testing <- data.frame(
  var1 = c(1, 6, 17)
)

dict <- data.frame(code = c(1, 6, 17), abbr = c('ICMP', 'TCP', 'UDP'))

merge(testing, dict, by.x = "var1", by.y = "code")
#  var1 abbr
#1    1 ICMP
#2    6  TCP
#3   17  UDP

testing$var1 <- merge(testing, dict, by.x = "var1", by.y = "code")$abbr

There is a number of options. First, you can use strings as indices:

dict <- c("1" = "ICMP", "6" = "TCP")
dict[ as.character(testing$var) ]

You can achieve the same by doing names(dict) <- c(1, 6).

Then, you can use a reverse hash:

dict <- c(ICMP = 1, TCP = 6)
names(dict)[ match(testing$var1, dict) ]