TUN-7424: Add CORS headers to host_details responses

vendor/github.com/go-chi/cors/utils.go

@@ -0,0 +1,70 @@
+package cors
+
+import "strings"
+
+const toLower = 'a' - 'A'
+
+type converter func(string) string
+
+type wildcard struct {
+	prefix string
+	suffix string
+}
+
+func (w wildcard) match(s string) bool {
+	return len(s) >= len(w.prefix+w.suffix) && strings.HasPrefix(s, w.prefix) && strings.HasSuffix(s, w.suffix)
+}
+
+// convert converts a list of string using the passed converter function
+func convert(s []string, c converter) []string {
+	out := []string{}
+	for _, i := range s {
+		out = append(out, c(i))
+	}
+	return out
+}
+
+// parseHeaderList tokenize + normalize a string containing a list of headers
+func parseHeaderList(headerList string) []string {
+	l := len(headerList)
+	h := make([]byte, 0, l)
+	upper := true
+	// Estimate the number headers in order to allocate the right splice size
+	t := 0
+	for i := 0; i < l; i++ {
+		if headerList[i] == ',' {
+			t++
+		}
+	}
+	headers := make([]string, 0, t)
+	for i := 0; i < l; i++ {
+		b := headerList[i]
+		if b >= 'a' && b <= 'z' {
+			if upper {
+				h = append(h, b-toLower)
+			} else {
+				h = append(h, b)
+			}
+		} else if b >= 'A' && b <= 'Z' {
+			if !upper {
+				h = append(h, b+toLower)
+			} else {
+				h = append(h, b)
+			}
+		} else if b == '-' || b == '_' || b == '.' || (b >= '0' && b <= '9') {
+			h = append(h, b)
+		}
+
+		if b == ' ' || b == ',' || i == l-1 {
+			if len(h) > 0 {
+				// Flush the found header
+				headers = append(headers, string(h))
+				h = h[:0]
+				upper = true
+			}
+		} else {
+			upper = b == '-'
+		}
+	}
+	return headers
+}