feat: add sni-misdirect plugin for go (#720)

Signed-off-by: sjcsjc123 <1401189096@qq.com>

plugins/wasm-go/extensions/sni-misdirect/main.go

@@ -0,0 +1,94 @@
+package main
+
+import (
+	"strings"
+
+	"github.com/alibaba/higress/plugins/wasm-go/pkg/wrapper"
+	"github.com/tetratelabs/proxy-wasm-go-sdk/proxywasm"
+	"github.com/tetratelabs/proxy-wasm-go-sdk/proxywasm/types"
+)
+
+func main() {
+	wrapper.SetCtx(
+		"sni-misdirect",
+		wrapper.ProcessRequestHeadersBy(onHttpRequestHeaders),
+	)
+}
+
+type Config struct {
+}
+
+func onHttpRequestHeaders(ctx wrapper.HttpContext, config Config, log wrapper.Log) types.Action {
+	// no need to check HTTP/1.0 and HTTP/1.1
+	protocol, err := proxywasm.GetProperty([]string{"request", "protocol"})
+	if err != nil {
+		log.Errorf("failed to get request protocol: %v", err)
+		return types.ActionContinue
+	}
+	if strings.HasPrefix(string(protocol), "HTTP/1") {
+		return types.ActionContinue
+	}
+	// no need to check http scheme
+	scheme := ctx.Scheme()
+	if scheme != "https" {
+		return types.ActionContinue
+	}
+	// no need to check grpc
+	contentType, err := proxywasm.GetHttpRequestHeader("content-type")
+	if err != nil {
+		log.Errorf("failed to get request content-type: %v", err)
+		return types.ActionContinue
+	}
+	if strings.HasPrefix(contentType, "application/grpc") {
+		return types.ActionContinue
+	}
+	// get sni
+	sni, err := proxywasm.GetProperty([]string{"connection", "requested_server_name"})
+	if err != nil {
+		log.Errorf("failed to get requested_server_name: %v", err)
+		return types.ActionContinue
+	}
+	// get authority
+	host, err := proxywasm.GetHttpRequestHeader(":authority")
+	if err != nil {
+		log.Errorf("failed to get request authority: %v", err)
+		return types.ActionContinue
+	}
+	host = stripPortFromHost(host)
+	if string(sni) == host {
+		return types.ActionContinue
+	}
+	if !strings.HasPrefix(string(sni), "*.") {
+		proxywasm.SendHttpResponse(421, nil, []byte("Misdirected Request"), -1)
+		return types.ActionPause
+	}
+	if !strings.Contains(host, string(sni)[1:]) {
+		proxywasm.SendHttpResponse(421, nil, []byte("Misdirected Request"), -1)
+		return types.ActionPause
+	}
+	return types.ActionContinue
+}
+
+func stripPortFromHost(requestHost string) string {
+	// Find the last occurrence of ':' to locate the port.
+	portStart := strings.LastIndex(requestHost, ":")
+
+	// Check if ':' is found.
+	if portStart != -1 {
+		// According to RFC3986, IPv6 address is always enclosed in "[]".
+		// section 3.2.2.
+		v6EndIndex := strings.LastIndex(requestHost, "]")
+
+		// Check if ']' is found and its position is after the ':'.
+		if v6EndIndex == -1 || v6EndIndex < portStart {
+			// Check if there are characters after ':'.
+			if portStart+1 <= len(requestHost) {
+				// Return the substring without the port.
+				return requestHost[:portStart]
+			}
+		}
+	}
+
+	// If no port is found or the conditions are not met, return the original requestHost.
+	return requestHost
+}