From 5929d521715610c9dd14898ebbe1d188d5de8937 Mon Sep 17 00:00:00 2001
From: Egor Seredin <4819888+agmt@users.noreply.github.com>
Date: Sat, 9 Oct 2021 09:38:51 +0900
Subject: [PATCH 1/2] ClientIP: check every proxy for trustiness (#2844)

---
 context.go      | 39 ++++++++++++++++++++-------------------
 context_test.go |  2 +-
 2 files changed, 21 insertions(+), 20 deletions(-)

diff --git a/context.go b/context.go
index d211098b..bea95cca 100644
--- a/context.go
+++ b/context.go
@@ -766,7 +766,7 @@ func (c *Context) ClientIP() string {
 
 	if trusted && c.engine.ForwardedByClientIP && c.engine.RemoteIPHeaders != nil {
 		for _, headerName := range c.engine.RemoteIPHeaders {
-			ip, valid := validateHeader(c.requestHeader(headerName))
+			ip, valid := c.engine.validateHeader(c.requestHeader(headerName))
 			if valid {
 				return ip
 			}
@@ -775,6 +775,17 @@ func (c *Context) ClientIP() string {
 	return remoteIP.String()
 }
 
+func (e *Engine) isTrustedProxy(ip net.IP) bool {
+	if e.trustedCIDRs != nil {
+		for _, cidr := range e.trustedCIDRs {
+			if cidr.Contains(ip) {
+				return true
+			}
+		}
+	}
+	return false
+}
+
 // RemoteIP parses the IP from Request.RemoteAddr, normalizes and returns the IP (without the port).
 // It also checks if the remoteIP is a trusted proxy or not.
 // In order to perform this validation, it will see if the IP is contained within at least one of the CIDR blocks
@@ -789,35 +800,25 @@ func (c *Context) RemoteIP() (net.IP, bool) {
 		return nil, false
 	}
 
-	if c.engine.trustedCIDRs != nil {
-		for _, cidr := range c.engine.trustedCIDRs {
-			if cidr.Contains(remoteIP) {
-				return remoteIP, true
-			}
-		}
-	}
-
-	return remoteIP, false
+	return remoteIP, c.engine.isTrustedProxy(remoteIP)
 }
 
-func validateHeader(header string) (clientIP string, valid bool) {
+func (e *Engine) validateHeader(header string) (clientIP string, valid bool) {
 	if header == "" {
 		return "", false
 	}
 	items := strings.Split(header, ",")
-	for i, ipStr := range items {
-		ipStr = strings.TrimSpace(ipStr)
+	for i := len(items) - 1; i >= 0; i-- {
+		ipStr := strings.TrimSpace(items[i])
 		ip := net.ParseIP(ipStr)
 		if ip == nil {
 			return "", false
 		}
 
-		// We need to return the first IP in the list, but,
-		// we should not early return since we need to validate that
-		// the rest of the header is syntactically valid
-		if i == 0 {
-			clientIP = ipStr
-			valid = true
+		// X-Forwarded-For is appended by proxy
+		// Check IPs in reverse order and stop when find untrusted proxy
+		if (i == 0) || (!e.isTrustedProxy(ip)) {
+			return ipStr, true
 		}
 	}
 	return
diff --git a/context_test.go b/context_test.go
index 07a35f52..e9fe88f9 100644
--- a/context_test.go
+++ b/context_test.go
@@ -1419,7 +1419,7 @@ func TestContextClientIP(t *testing.T) {
 
 	// Only trust RemoteAddr
 	_ = c.engine.SetTrustedProxies([]string{"40.40.40.40"})
-	assert.Equal(t, "20.20.20.20", c.ClientIP())
+	assert.Equal(t, "30.30.30.30", c.ClientIP())
 
 	// All steps are trusted
 	_ = c.engine.SetTrustedProxies([]string{"40.40.40.40", "30.30.30.30", "20.20.20.20"})

From 464535ff94799b012f90f15edcffd32e4abe32fa Mon Sep 17 00:00:00 2001
From: "dependabot[bot]" <49699333+dependabot[bot]@users.noreply.github.com>
Date: Tue, 19 Oct 2021 07:55:14 +0800
Subject: [PATCH 2/2] Bump github.com/goccy/go-json from 0.7.9 to 0.7.10
 (#2905)

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
---
 go.mod | 2 +-
 go.sum | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/go.mod b/go.mod
index c03439a0..c25eecf9 100644
--- a/go.mod
+++ b/go.mod
@@ -5,7 +5,7 @@ go 1.13
 require (
 	github.com/gin-contrib/sse v0.1.0
 	github.com/go-playground/validator/v10 v10.9.0
-	github.com/goccy/go-json v0.7.9
+	github.com/goccy/go-json v0.7.10
 	github.com/json-iterator/go v1.1.12
 	github.com/mattn/go-isatty v0.0.14
 	github.com/stretchr/testify v1.7.0
diff --git a/go.sum b/go.sum
index 7bf71f9f..51497a0b 100644
--- a/go.sum
+++ b/go.sum
@@ -12,8 +12,8 @@ github.com/go-playground/universal-translator v0.18.0 h1:82dyy6p4OuJq4/CByFNOn/j
 github.com/go-playground/universal-translator v0.18.0/go.mod h1:UvRDBj+xPUEGrFYl+lu/H90nyDXpg0fqeB/AQUGNTVA=
 github.com/go-playground/validator/v10 v10.9.0 h1:NgTtmN58D0m8+UuxtYmGztBJB7VnPgjj221I1QHci2A=
 github.com/go-playground/validator/v10 v10.9.0/go.mod h1:74x4gJWsvQexRdW8Pn3dXSGrTK4nAUsbPlLADvpJkos=
-github.com/goccy/go-json v0.7.9 h1:mSp3uo1tr6MXQTYopSNhHTUnJhd2zQ4Yk+HdJZP+ZRY=
-github.com/goccy/go-json v0.7.9/go.mod h1:6MelG93GURQebXPDq3khkgXZkazVtN9CRI+MGFi0w8I=
+github.com/goccy/go-json v0.7.10 h1:ulhbuNe1JqE68nMRXXTJRrUu0uhouf0VevLINxQq4Ec=
+github.com/goccy/go-json v0.7.10/go.mod h1:6MelG93GURQebXPDq3khkgXZkazVtN9CRI+MGFi0w8I=
 github.com/golang/protobuf v1.5.0/go.mod h1:FsONVRAS9T7sI+LIUmWTfcYkHO4aIWwzhcaSAoJOfIk=
 github.com/google/go-cmp v0.5.5 h1:Khx7svrCpmxxtHBq5j2mp/xVjsi8hQMfNLvJFAlrGgU=
 github.com/google/go-cmp v0.5.5/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=