From 26f1df27213fd1208d1691ffda80ee21f90c34a3 Mon Sep 17 00:00:00 2001
From: Evgeniy Kulikov <kim@nspcc.ru>
Date: Tue, 11 Aug 2020 14:27:31 +0300
Subject: [PATCH] Refactoring request info

- simplify
- more usable

Signed-off-by: Evgeniy Kulikov <kim@nspcc.ru>
---
 api/reqinfo.go | 123 ++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 106 insertions(+), 17 deletions(-)

diff --git a/api/reqinfo.go b/api/reqinfo.go
index cc4dc2e0..606ada4e 100644
--- a/api/reqinfo.go
+++ b/api/reqinfo.go
@@ -2,7 +2,14 @@ package api
 
 import (
 	"context"
+	"net"
+	"net/http"
+	"net/url"
+	"regexp"
+	"strings"
 	"sync"
+
+	"github.com/gorilla/mux"
 )
 
 type (
@@ -25,6 +32,12 @@ type (
 		ObjectName   string   // Object name
 		tags         []KeyVal // Any additional info not accommodated by above fields
 	}
+
+	ObjectRequest struct {
+		Bucket string
+		Object string
+		Method string
+	}
 )
 
 // Key used for Get/SetReqInfo
@@ -32,17 +45,97 @@ type contextKeyType string
 
 const ctxRequestInfo = contextKeyType("NeoFS-S3-Gate")
 
+var (
+	// De-facto standard header keys.
+	xForwardedFor = http.CanonicalHeaderKey("X-Forwarded-For")
+	xRealIP       = http.CanonicalHeaderKey("X-Real-IP")
+)
+
+var (
+	// RFC7239 defines a new "Forwarded: " header designed to replace the
+	// existing use of X-Forwarded-* headers.
+	// e.g. Forwarded: for=192.0.2.60;proto=https;by=203.0.113.43
+	forwarded = http.CanonicalHeaderKey("Forwarded")
+	// Allows for a sub-match of the first value after 'for=' to the next
+	// comma, semi-colon or space. The match is case-insensitive.
+	forRegex = regexp.MustCompile(`(?i)(?:for=)([^(;|, )]+)(.*)`)
+)
+
+// GetSourceIP retrieves the IP from the X-Forwarded-For, X-Real-IP and RFC7239
+// Forwarded headers (in that order), falls back to r.RemoteAddr when all
+// else fails.
+func GetSourceIP(r *http.Request) string {
+	var addr string
+
+	if fwd := r.Header.Get(xForwardedFor); fwd != "" {
+		// Only grab the first (client) address. Note that '192.168.0.1,
+		// 10.1.1.1' is a valid key for X-Forwarded-For where addresses after
+		// the first may represent forwarding proxies earlier in the chain.
+		s := strings.Index(fwd, ", ")
+		if s == -1 {
+			s = len(fwd)
+		}
+		addr = fwd[:s]
+	} else if fwd := r.Header.Get(xRealIP); fwd != "" {
+		// X-Real-IP should only contain one IP address (the client making the
+		// request).
+		addr = fwd
+	} else if fwd := r.Header.Get(forwarded); fwd != "" {
+		// match should contain at least two elements if the protocol was
+		// specified in the Forwarded header. The first element will always be
+		// the 'for=' capture, which we ignore. In the case of multiple IP
+		// addresses (for=8.8.8.8, 8.8.4.4, 172.16.1.20 is valid) we only
+		// extract the first, which should be the client IP.
+		if match := forRegex.FindStringSubmatch(fwd); len(match) > 1 {
+			// IPv6 addresses in Forwarded headers are quoted-strings. We strip
+			// these quotes.
+			addr = strings.Trim(match[1], `"`)
+		}
+	}
+
+	if addr != "" {
+		return addr
+	}
+
+	// Default to remote address if headers not set.
+	addr, _, _ = net.SplitHostPort(r.RemoteAddr)
+	return addr
+}
+
+func prepareContext(w http.ResponseWriter, r *http.Request) context.Context {
+	vars := mux.Vars(r)
+	bucket := vars["bucket"]
+	object, err := url.PathUnescape(vars["object"])
+	if err != nil {
+		object = vars["object"]
+	}
+	prefix, err := url.QueryUnescape(vars["prefix"])
+	if err != nil {
+		prefix = vars["prefix"]
+	}
+	if prefix != "" {
+		object = prefix
+	}
+	return SetReqInfo(r.Context(),
+		// prepare request info
+		NewReqInfo(w, r, ObjectRequest{
+			Bucket: bucket,
+			Object: object,
+			Method: mux.CurrentRoute(r).GetName(),
+		}))
+}
+
 // NewReqInfo :
-func NewReqInfo(remoteHost, userAgent, deploymentID, requestID, api, bucket, object string) *ReqInfo {
-	req := ReqInfo{}
-	req.RemoteHost = remoteHost
-	req.UserAgent = userAgent
-	req.API = api
-	req.DeploymentID = deploymentID
-	req.RequestID = requestID
-	req.BucketName = bucket
-	req.ObjectName = object
-	return &req
+func NewReqInfo(w http.ResponseWriter, r *http.Request, req ObjectRequest) *ReqInfo {
+	return &ReqInfo{
+		API:          req.Method,
+		BucketName:   req.Bucket,
+		ObjectName:   req.Object,
+		UserAgent:    r.UserAgent(),
+		RemoteHost:   GetSourceIP(r),
+		RequestID:    GetRequestID(w),
+		DeploymentID: deploymentID.String(),
+	}
 }
 
 // AppendTags - appends key/val to ReqInfo.tags
@@ -99,13 +192,9 @@ func SetReqInfo(ctx context.Context, req *ReqInfo) context.Context {
 
 // GetReqInfo returns ReqInfo if set.
 func GetReqInfo(ctx context.Context) *ReqInfo {
-	if ctx != nil {
-		r, ok := ctx.Value(ctxRequestInfo).(*ReqInfo)
-		if ok {
-			return r
-		}
-		r = &ReqInfo{}
-		SetReqInfo(ctx, r)
+	if ctx == nil {
+		return nil
+	} else if r, ok := ctx.Value(ctxRequestInfo).(*ReqInfo); ok {
 		return r
 	}
 	return nil