我感到恐慌，我試圖理解它，但我不確定它為什么會恐慌。錯誤如下所示：main.HTTPSNonWWWRedirect.func1(0x9a5a20, 0xc42015c2a0, 0xc420441400) /srv/www/go/src/srorapp.no/handler.go:119 +0x1efnet/http.HandlerFunc.ServeHTTP(0xc4200c5f20, 0x9a5a20, 0xc42015c2a0, 0xc420441400) /usr/local/go/src/net/http/server.go:1918 +0x44net/http.serverHandler.ServeHTTP(0xc4200696c0, 0x9a5a20, 0xc42015c2a0, 0xc420441400) /usr/local/go/src/net/http/server.go:2619 +0xb4net/http.(*conn).serve(0xc42006d180, 0x9a5fa0, 0xc42031e840) /usr/local/go/src/net/http/server.go:1801 +0x71dcreated by net/http.(*Server).Serve /usr/local/go/src/net/http/server.go:2720 +0x288它看起來像是從一個名為 HTTPSNonWWWRedirect 的函數中觸發的。這是我創建的 http 中間件：// HTTPSNonWWWRedirect redirects http requests to https non www.func HTTPSNonWWWRedirect(next http.Handler) http.Handler { return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { if r.TLS != nil { // If already using HTTPS then continue. next.ServeHTTP(w, r) return } u := *r.URL u.Scheme = "https" if r.Host[:3] != "www" { u.Host = r.Host http.Redirect(w, r, u.String(), http.StatusMovedPermanently) return } u.Host = r.Host[4:] http.Redirect(w, r, u.String(), http.StatusMovedPermanently) })}此功能與以下一起使用：// NonWWWRedirect redirects www requests to non www.func NonWWWRedirect(next http.Handler) http.Handler { return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { if r.Host[:3] != "www" { // If already non www, then continue. next.ServeHTTP(w, r) return } u := *r.URL u.Host = r.Host[4:] u.Scheme = utils.Scheme(r) http.Redirect(w, r, u.String(), http.StatusMovedPermanently) })}
1 回答
qq_花開花謝_0
TA貢獻1835條經驗 獲得超7個贊
1. 問題
包含handler.go:119一個if聲明。您試圖從標題中獲取前三個字符Host。
if r.Host[:3] != "www" {
u.Host = r.Host
http.Redirect(w, r, u.String(), http.StatusMovedPermanently)
return
}
正常情況下，r.Host會存儲請求的URL信息。除非標Host頭在請求中明確更改。來自net/http 包文檔：
type Request struct {
// ...
// For server requests Host specifies the host on which the URL
// is sought. Per RFC 7230, section 5.4, this is either the value
// of the "Host" header or the host name given in the URL itself.
// It may be of the form "host:port". For international domain
// names, Host may be in Punycode or Unicode form. Use
// golang.org/x/net/idna to convert it to either format if
// needed.
// To prevent DNS rebinding attacks, server Handlers should
// validate that the Host header has a value for which the
// Handler considers itself authoritative. The included
// ServeMux supports patterns registered to particular host
// names and thus protects its registered Handlers.
//
// For client requests Host optionally overrides the Host
// header to send. If empty, the Request.Write method uses
// the value of URL.Host. Host may contain an international
// domain name.
Host string
// ...
}
所以恐慌的發生是因為r.Host填充了空字符串，或者一些字符數小于 3 的字符串。
2. 測試
我使用 go 創建了非常簡單的 Web 應用程序，它打印r.Host[:3]. 我使用 curl 對其進行了測試，并將Host標頭設置為空。
curl --verbose --header 'Host: ' http://localhost:8080
它會引發恐慌，我很確定這和你得到的一樣是恐慌錯誤。
2018/12/07 08:11:54 http: panic serving 127.0.0.1:50889: runtime error: slice bounds out of range
goroutine 37 [running]:
net/http.(*conn).serve.func1(0xc0001380a0)
/usr/local/opt/go/libexec/src/net/http/server.go:1746 +0xd0
panic(0x125c0c0, 0x14964d0)
/usr/local/opt/go/libexec/src/runtime/panic.go:513 +0x1b9
main.main.func1(0x12efa80, 0xc00014c2a0, 0xc000162300)
/Users/novalagung/Desktop/test.go:11 +0x13d
net/http.HandlerFunc.ServeHTTP(0x12bcd98, 0x12efa80, 0xc00014c2a0, 0xc000162300)
/usr/local/opt/go/libexec/src/net/http/server.go:1964 +0x44
net/http.(*ServeMux).ServeHTTP(0x14a17a0, 0x12efa80, 0xc00014c2a0, 0xc000162300)
/usr/local/opt/go/libexec/src/net/http/server.go:2361 +0x127
net/http.serverHandler.ServeHTTP(0xc000093110, 0x12efa80, 0xc00014c2a0, 0xc000162300)
/usr/local/opt/go/libexec/src/net/http/server.go:2741 +0xab
net/http.(*conn).serve(0xc0001380a0, 0x12efc80, 0xc000146100)
/usr/local/opt/go/libexec/src/net/http/server.go:1847 +0x646
created by net/http.(*Server).Serve
/usr/local/opt/go/libexec/src/net/http/server.go:2851 +0x2f5
3.解決方案
解決方法很簡單，只要確保該r.Host值不是空字符串且長度大于 2 即可。更好地使用strings.HasPrefix()來完成此操作。
if strings.HasPrefix(r.Host, "www") {
u.Host = r.Host
http.Redirect(w, r, u.String(), http.StatusMovedPermanently)
return
}
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