core: Add support for `d` duration unit (#3323)

* caddy: Add support for `d` duration unit

* Improvements to ParseDuration; add unit tests

Co-authored-by: Matthew Holt <mholt@users.noreply.github.com>

1 files changed, 30 insertions, 2 deletions

diff --git a/caddy.go b/caddy.go
index 00a56e7..1184bc9 100644
--- a/caddy.go
+++ b/caddy.go
@@ -486,7 +486,7 @@ func Validate(cfg *Config) error {
 // Duration can be an integer or a string. An integer is
 // interpreted as nanoseconds. If a string, it is a Go
 // time.Duration value such as `300ms`, `1.5h`, or `2h45m`;
-// valid units are `ns`, `us`/`µs`, `ms`, `s`, `m`, and `h`.
+// valid units are `ns`, `us`/`µs`, `ms`, `s`, `m`, `h`, and `d`.
 type Duration time.Duration
 
 // UnmarshalJSON satisfies json.Unmarshaler.
@@ -497,7 +497,7 @@ func (d *Duration) UnmarshalJSON(b []byte) error {
 	var dur time.Duration
 	var err error
 	if b[0] == byte('"') && b[len(b)-1] == byte('"') {
-		dur, err = time.ParseDuration(strings.Trim(string(b), `"`))
+		dur, err = ParseDuration(strings.Trim(string(b), `"`))
 	} else {
 		err = json.Unmarshal(b, &dur)
 	}
@@ -505,6 +505,34 @@ func (d *Duration) UnmarshalJSON(b []byte) error {
 	return err
 }
 
+// ParseDuration parses a duration string, adding
+// support for the "d" unit meaning number of days,
+// where a day is assumed to be 24h.
+func ParseDuration(s string) (time.Duration, error) {
+	var inNumber bool
+	var numStart int
+	for i := 0; i < len(s); i++ {
+		ch := s[i]
+		if ch == 'd' {
+			daysStr := s[numStart:i]
+			days, err := strconv.ParseFloat(daysStr, 64)
+			if err != nil {
+				return 0, err
+			}
+			hours := days * 24.0
+			hoursStr := strconv.FormatFloat(hours, 'f', -1, 64)
+			s = s[:numStart] + hoursStr + "h" + s[i+1:]
+			i--
+			continue
+		}
+		if !inNumber {
+			numStart = i
+		}
+		inNumber = (ch >= '0' && ch <= '9') || ch == '.' || ch == '-' || ch == '+'
+	}
+	return time.ParseDuration(s)
+}
+
 // GoModule returns the build info of this Caddy
 // build from debug.BuildInfo (requires Go modules).
 // If no version information is available, a non-nil