91 lines
2.3 KiB
Go
91 lines
2.3 KiB
Go
package cors
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import (
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"net/http"
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"strconv"
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"strings"
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"time"
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)
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type converter func(string) string
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func generateNormalHeaders(c Config) http.Header {
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headers := make(http.Header)
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if c.AllowCredentials {
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headers.Set("Access-Control-Allow-Credentials", "true")
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}
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if len(c.ExposeHeaders) > 0 {
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exposeHeaders := convert(normalize(c.ExposeHeaders), http.CanonicalHeaderKey)
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headers.Set("Access-Control-Expose-Headers", strings.Join(exposeHeaders, ","))
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}
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if c.AllowAllOrigins {
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headers.Set("Access-Control-Allow-Origin", "*")
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} else {
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headers.Set("Vary", "Origin")
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}
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return headers
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}
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func generatePreflightHeaders(c Config) http.Header {
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headers := make(http.Header)
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if c.AllowCredentials {
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headers.Set("Access-Control-Allow-Credentials", "true")
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}
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if len(c.AllowMethods) > 0 {
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allowMethods := convert(normalize(c.AllowMethods), strings.ToUpper)
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value := strings.Join(allowMethods, ",")
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headers.Set("Access-Control-Allow-Methods", value)
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}
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if len(c.AllowHeaders) > 0 {
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allowHeaders := convert(normalize(c.AllowHeaders), http.CanonicalHeaderKey)
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value := strings.Join(allowHeaders, ",")
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headers.Set("Access-Control-Allow-Headers", value)
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}
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if c.MaxAge > time.Duration(0) {
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value := strconv.FormatInt(int64(c.MaxAge/time.Second), 10)
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headers.Set("Access-Control-Max-Age", value)
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}
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if c.AllowPrivateNetwork {
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headers.Set("Access-Control-Allow-Private-Network", "true")
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}
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if c.AllowAllOrigins {
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headers.Set("Access-Control-Allow-Origin", "*")
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} else {
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// Always set Vary headers
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// see https://github.com/rs/cors/issues/10,
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// https://github.com/rs/cors/commit/dbdca4d95feaa7511a46e6f1efb3b3aa505bc43f#commitcomment-12352001
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headers.Add("Vary", "Origin")
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headers.Add("Vary", "Access-Control-Request-Method")
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headers.Add("Vary", "Access-Control-Request-Headers")
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}
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return headers
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}
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func normalize(values []string) []string {
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if values == nil {
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return nil
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}
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distinctMap := make(map[string]bool, len(values))
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normalized := make([]string, 0, len(values))
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for _, value := range values {
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value = strings.TrimSpace(value)
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value = strings.ToLower(value)
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if _, seen := distinctMap[value]; !seen {
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normalized = append(normalized, value)
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distinctMap[value] = true
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}
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}
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return normalized
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}
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func convert(s []string, c converter) []string {
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var out []string
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for _, i := range s {
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out = append(out, c(i))
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}
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return out
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}
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