map: Remove infinite recursion check (#5094)

It was not accurate. Placeholders could be used in outputs that are defined in the same mapping as long as that placeholder does not do the same. A more general solution would be to detect it at run-time in the replacer directly, but that's a bit tedious and will require allocations I think. A better implementation of this check could still be done, but I don't know if it would always be accurate. Could be a "best-effort" thing? But I've also never heard of an actual case where someone configured infinite recursion...

Matt Holt committed Sep 29, 2022 at 12:46 UTC 5e52bbb1369b7444700427539e4dd532ed13ac6d

1 file changed +1 -10

modules/caddyhttp/map/map.go

+1 -10

@@ -109,22 +109,13 @@ func (h *Handler) Validate() error {

109 }

110 seen[input] = i

111

112 - // prevent infinite recursion

113 - for _, out := range m.Outputs {

114 - for _, dest := range h.Destinations {

115 - if strings.Contains(caddy.ToString(out), dest) ||

116 - strings.Contains(m.Input, dest) {

117 - return fmt.Errorf("mapping %d requires value of {%s} to define value of {%s}: infinite recursion", i, dest, dest)

118 - }

119 - }

120 - }

121 -

112 // ensure mappings have 1:1 output-to-destination correspondence

113 nOut := len(m.Outputs)

114 if nOut != nDest {

115 return fmt.Errorf("mapping %d has %d outputs but there are %d destinations defined", i, nOut, nDest)

116 }

117 }

118 +

119 return nil

120 }

121