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Remove square brackets from ipv6 addresses in XFF (#2182)
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Remove square brackets from ipv6 addresses in XFF
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@42wim
42wim authored Nov 24, 2022
1 parent 36ff0b3 commit 7544796
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Showing 4 changed files with 125 additions and 3 deletions.
7 changes: 6 additions & 1 deletion context.go
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Original file line number Diff line number Diff line change
Expand Up @@ -282,11 +282,16 @@ func (c *context) RealIP() string {
if ip := c.request.Header.Get(HeaderXForwardedFor); ip != "" {
i := strings.IndexAny(ip, ",")
if i > 0 {
return strings.TrimSpace(ip[:i])
xffip := strings.TrimSpace(ip[:i])
xffip = strings.TrimPrefix(xffip, "[")
xffip = strings.TrimSuffix(xffip, "]")
return xffip
}
return ip
}
if ip := c.request.Header.Get(HeaderXRealIP); ip != "" {
ip = strings.TrimPrefix(ip, "[")
ip = strings.TrimSuffix(ip, "]")
return ip
}
ra, _, _ := net.SplitHostPort(c.request.RemoteAddr)
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36 changes: 35 additions & 1 deletion context_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -97,7 +97,6 @@ func (responseWriterErr) Write([]byte) (int, error) {
}

func (responseWriterErr) WriteHeader(statusCode int) {

}

func TestContext(t *testing.T) {
Expand Down Expand Up @@ -904,6 +903,30 @@ func TestContext_RealIP(t *testing.T) {
},
"127.0.0.1",
},
{
&context{
request: &http.Request{
Header: http.Header{HeaderXForwardedFor: []string{"[2001:db8:85a3:8d3:1319:8a2e:370:7348], 2001:db8::1, "}},
},
},
"2001:db8:85a3:8d3:1319:8a2e:370:7348",
},
{
&context{
request: &http.Request{
Header: http.Header{HeaderXForwardedFor: []string{"[2001:db8:85a3:8d3:1319:8a2e:370:7348],[2001:db8::1]"}},
},
},
"2001:db8:85a3:8d3:1319:8a2e:370:7348",
},
{
&context{
request: &http.Request{
Header: http.Header{HeaderXForwardedFor: []string{"2001:db8:85a3:8d3:1319:8a2e:370:7348"}},
},
},
"2001:db8:85a3:8d3:1319:8a2e:370:7348",
},
{
&context{
request: &http.Request{
Expand All @@ -914,6 +937,17 @@ func TestContext_RealIP(t *testing.T) {
},
"192.168.0.1",
},
{
&context{
request: &http.Request{
Header: http.Header{
"X-Real-Ip": []string{"[2001:db8::1]"},
},
},
},
"2001:db8::1",
},

{
&context{
request: &http.Request{
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7 changes: 6 additions & 1 deletion ip.go
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Original file line number Diff line number Diff line change
Expand Up @@ -227,6 +227,8 @@ func ExtractIPFromRealIPHeader(options ...TrustOption) IPExtractor {
return func(req *http.Request) string {
realIP := req.Header.Get(HeaderXRealIP)
if realIP != "" {
realIP = strings.TrimPrefix(realIP, "[")
realIP = strings.TrimSuffix(realIP, "]")
if ip := net.ParseIP(realIP); ip != nil && checker.trust(ip) {
return realIP
}
Expand All @@ -248,7 +250,10 @@ func ExtractIPFromXFFHeader(options ...TrustOption) IPExtractor {
}
ips := append(strings.Split(strings.Join(xffs, ","), ","), directIP)
for i := len(ips) - 1; i >= 0; i-- {
ip := net.ParseIP(strings.TrimSpace(ips[i]))
ips[i] = strings.TrimSpace(ips[i])
ips[i] = strings.TrimPrefix(ips[i], "[")
ips[i] = strings.TrimSuffix(ips[i], "]")
ip := net.ParseIP(ips[i])
if ip == nil {
// Unable to parse IP; cannot trust entire records
return directIP
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78 changes: 78 additions & 0 deletions ip_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -459,6 +459,7 @@ func TestExtractIPDirect(t *testing.T) {

func TestExtractIPFromRealIPHeader(t *testing.T) {
_, ipForRemoteAddrExternalRange, _ := net.ParseCIDR("203.0.113.199/24")
_, ipv6ForRemoteAddrExternalRange, _ := net.ParseCIDR("2001:db8::/64")

var testCases = []struct {
name string
Expand Down Expand Up @@ -493,6 +494,16 @@ func TestExtractIPFromRealIPHeader(t *testing.T) {
},
expectIP: "203.0.113.1",
},
{
name: "request is from external IP has valid + UNTRUSTED external X-Real-Ip header, extract IP from remote addr",
whenRequest: http.Request{
Header: http.Header{
HeaderXRealIP: []string{"[2001:db8::113:199]"}, // <-- this is untrusted
},
RemoteAddr: "[2001:db8::113:1]:8080",
},
expectIP: "2001:db8::113:1",
},
{
name: "request is from external IP has valid + TRUSTED X-Real-Ip header, extract IP from X-Real-Ip header",
givenTrustOptions: []TrustOption{ // case for "trust direct-facing proxy"
Expand All @@ -506,6 +517,19 @@ func TestExtractIPFromRealIPHeader(t *testing.T) {
},
expectIP: "203.0.113.199",
},
{
name: "request is from external IP has valid + TRUSTED X-Real-Ip header, extract IP from X-Real-Ip header",
givenTrustOptions: []TrustOption{ // case for "trust direct-facing proxy"
TrustIPRange(ipv6ForRemoteAddrExternalRange), // we trust external IP range "2001:db8::/64"
},
whenRequest: http.Request{
Header: http.Header{
HeaderXRealIP: []string{"[2001:db8::113:199]"},
},
RemoteAddr: "[2001:db8::113:1]:8080",
},
expectIP: "2001:db8::113:199",
},
{
name: "request is from external IP has XFF and valid + TRUSTED X-Real-Ip header, extract IP from X-Real-Ip header",
givenTrustOptions: []TrustOption{ // case for "trust direct-facing proxy"
Expand All @@ -520,6 +544,20 @@ func TestExtractIPFromRealIPHeader(t *testing.T) {
},
expectIP: "203.0.113.199",
},
{
name: "request is from external IP has XFF and valid + TRUSTED X-Real-Ip header, extract IP from X-Real-Ip header",
givenTrustOptions: []TrustOption{ // case for "trust direct-facing proxy"
TrustIPRange(ipv6ForRemoteAddrExternalRange), // we trust external IP range "2001:db8::/64"
},
whenRequest: http.Request{
Header: http.Header{
HeaderXRealIP: []string{"[2001:db8::113:199]"},
HeaderXForwardedFor: []string{"[2001:db8::113:198], [2001:db8::113:197]"}, // <-- should not affect anything
},
RemoteAddr: "[2001:db8::113:1]:8080",
},
expectIP: "2001:db8::113:199",
},
}

for _, tc := range testCases {
Expand All @@ -532,6 +570,7 @@ func TestExtractIPFromRealIPHeader(t *testing.T) {

func TestExtractIPFromXFFHeader(t *testing.T) {
_, ipForRemoteAddrExternalRange, _ := net.ParseCIDR("203.0.113.199/24")
_, ipv6ForRemoteAddrExternalRange, _ := net.ParseCIDR("2001:db8::/64")

var testCases = []struct {
name string
Expand Down Expand Up @@ -566,6 +605,16 @@ func TestExtractIPFromXFFHeader(t *testing.T) {
},
expectIP: "127.0.0.3",
},
{
name: "request trusts all IPs in XFF header, extract IP from furthest in XFF chain",
whenRequest: http.Request{
Header: http.Header{
HeaderXForwardedFor: []string{"[fe80::3], [fe80::2], [fe80::1]"},
},
RemoteAddr: "[fe80::1]:8080",
},
expectIP: "fe80::3",
},
{
name: "request is from external IP has valid + UNTRUSTED external XFF header, extract IP from remote addr",
whenRequest: http.Request{
Expand All @@ -576,6 +625,16 @@ func TestExtractIPFromXFFHeader(t *testing.T) {
},
expectIP: "203.0.113.1",
},
{
name: "request is from external IP has valid + UNTRUSTED external XFF header, extract IP from remote addr",
whenRequest: http.Request{
Header: http.Header{
HeaderXForwardedFor: []string{"[2001:db8::1]"}, // <-- this is untrusted
},
RemoteAddr: "[2001:db8::2]:8080",
},
expectIP: "2001:db8::2",
},
{
name: "request is from external IP is valid and has some IPs TRUSTED XFF header, extract IP from XFF header",
givenTrustOptions: []TrustOption{
Expand All @@ -595,6 +654,25 @@ func TestExtractIPFromXFFHeader(t *testing.T) {
},
expectIP: "203.0.100.100", // this is first trusted IP in XFF chain
},
{
name: "request is from external IP is valid and has some IPs TRUSTED XFF header, extract IP from XFF header",
givenTrustOptions: []TrustOption{
TrustIPRange(ipv6ForRemoteAddrExternalRange), // we trust external IP range "2001:db8::/64"
},
// from request its seems that request has been proxied through 6 servers.
// 1) 2001:db8:1::1:100 (this is external IP set by 2001:db8:2::100:100 which we do not trust - could be spoofed)
// 2) 2001:db8:2::100:100 (this is outside of our network but set by 2001:db8::113:199 which we trust to set correct IPs)
// 3) 2001:db8::113:199 (we trust, for example maybe our proxy from some other office)
// 4) fd12:3456:789a:1::1 (internal IP, some internal upstream loadbalancer ala SSL offloading with F5 products)
// 5) fe80::1 (is proxy on localhost. maybe we have Nginx in front of our Echo instance doing some routing)
whenRequest: http.Request{
Header: http.Header{
HeaderXForwardedFor: []string{"[2001:db8:1::1:100], [2001:db8:2::100:100], [2001:db8::113:199], [fd12:3456:789a:1::1]"},
},
RemoteAddr: "[fe80::1]:8080", // IP of proxy upstream of our APP
},
expectIP: "2001:db8:2::100:100", // this is first trusted IP in XFF chain
},
}

for _, tc := range testCases {
Expand Down

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