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Fix headless JS loading with -tlsi and addheader/setheader #7325

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Fix headless JS loading with -tlsi and addheader/setheader #7325

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24 changes: 22 additions & 2 deletions pkg/protocols/headless/engine/http_client.go
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Original file line number Diff line number Diff line change
Expand Up @@ -10,6 +10,7 @@ import (
"net/url"
"time"

"golang.org/x/net/http2"
"golang.org/x/net/proxy"

"github.com/projectdiscovery/fastdialer/fastdialer/ja3/impersonate"
Expand Down Expand Up @@ -67,7 +68,7 @@ func newHttpClient(options *types.Options) (*http.Client, error) {
} else if options.AliveSocksProxy != "" {
socksURL, proxyErr := url.Parse(options.AliveSocksProxy)
if proxyErr != nil {
return nil, err
return nil, proxyErr
}
dialer, err := proxy.FromURL(socksURL, proxy.Direct)
if err != nil {
Expand All @@ -80,10 +81,28 @@ func newHttpClient(options *types.Options) (*http.Client, error) {
transport.DialContext = dc.DialContext
}

var roundTripper http.RoundTripper = transport

// TLS impersonation via utls advertises h2 in ALPN to mimic a real browser.
// Since utls returns *utls.UConn (not *tls.Conn), Go's http.Transport can't
// detect the negotiated protocol and tries HTTP/1.x on an h2 connection,
// causing "malformed HTTP response" errors. We use http2.Transport directly
// with utls dialing to properly handle h2 connections (see #6360).
if options.TlsImpersonate {
roundTripper = &http2.Transport{
DialTLSContext: func(ctx context.Context, network, addr string, _ *tls.Config) (net.Conn, error) {
return dialers.Fastdialer.DialTLSWithConfigImpersonate(ctx, network, addr, tlsConfig, impersonate.Random, nil)
},
TLSClientConfig: tlsConfig,
AllowHTTP: false,
DisableCompression: false,
}
}
Comment on lines +84 to +100
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@coderabbitai coderabbitai bot Apr 2, 2026

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⚠️ Potential issue | 🟠 Major

🧩 Analysis chain

🏁 Script executed:

#!/bin/bash
# Check if there's existing proxy handling with http2.Transport elsewhere in the codebase
echo "=== Searching for http2.Transport proxy handling patterns ==="
rg -n -C3 'http2\.Transport' --type=go

echo ""
echo "=== Check how fastdialer handles proxy with TLS impersonation ==="
ast-grep --pattern $'DialTLSWithConfigImpersonate($$$)'

Repository: projectdiscovery/nuclei

Length of output: 1340

🏁 Script executed:

#!/bin/bash
# Read the full context around lines 64-100 in http_client.go
echo "=== Full context of http_client.go lines 50-105 ==="
sed -n '50,105p' pkg/protocols/headless/engine/http_client.go | cat -n

echo ""
echo "=== Search for proxy configuration setup ==="
rg -n "Proxy|proxy|AliveHttpProxy|AliveSocksProxy" pkg/protocols/headless/engine/http_client.go -B2 -A2

echo ""
echo "=== Locate Fastdialer and DialTLSWithConfigImpersonate ==="
fd -name "*.go" -type f | xargs grep -l "DialTLSWithConfigImpersonate"

Repository: projectdiscovery/nuclei

Length of output: 3519

🏁 Script executed:

#!/bin/bash
# Find Fastdialer implementation
echo "=== Locating Fastdialer DialTLSWithConfigImpersonate ==="
fd "fastdialer" -type d

echo ""
echo "=== Search in common vendor/import paths ==="
fd -name "*.go" -type f 2>/dev/null | head -20 | xargs grep -l "DialTLSWithConfigImpersonate" 2>/dev/null | head -5

echo ""
echo "=== Alternative: check imports in http_client.go ==="
head -30 pkg/protocols/headless/engine/http_client.go | grep -E "import|dialers"

echo ""
echo "=== Check if fastdialer is external dependency ==="
if [ -f go.mod ]; then
  grep -i fastdialer go.mod | head -5
fi

Repository: projectdiscovery/nuclei

Length of output: 684

🏁 Script executed:

#!/bin/bash
# Verify http2.Transport capabilities and proxy handling
echo "=== Check golang.org/x/net/http2 import and usage ==="
grep -n "http2" pkg/protocols/headless/engine/http_client.go | head -10

echo ""
echo "=== Verify that http2.Transport is indeed without Proxy field ==="
# Check if anyone in codebase tries to set Proxy on http2.Transport
rg "http2\.Transport\s*\{" -A 15 pkg/

echo ""
echo "=== Check how this file uses roundTripper ==="
grep -n "roundTripper" pkg/protocols/headless/engine/http_client.go

Repository: projectdiscovery/nuclei

Length of output: 1748

Proxy configuration is lost when TLS impersonation is enabled.

When TlsImpersonate is true, the roundTripper is replaced with a new http2.Transport that doesn't incorporate any proxy settings configured on lines 64-82. If a user enables both -tlsi and a proxy (AliveHttpProxy or AliveSocksProxy), the proxy will be silently ignored.

The http2.Transport doesn't have a direct Proxy field. You need to integrate the proxy dialer into the DialTLSContext function for http2.Transport to preserve proxy support when TLS impersonation is enabled.

🤖 Prompt for AI Agents 
Verify each finding against the current code and only fix it if needed.

In `@pkg/protocols/headless/engine/http_client.go` around lines 84 - 100, The new
http2.Transport assigned to roundTripper when options.TlsImpersonate is true
ignores any proxy settings (AliveHttpProxy/AliveSocksProxy) set earlier; update
the DialTLSContext used in that http2.Transport to use the same proxy-aware
dialing logic as the original transport (i.e., route through the configured
HTTP/SOCKS proxy) instead of calling
dialers.Fastdialer.DialTLSWithConfigImpersonate directly. Concretely, modify the
DialTLSContext implementation in the http2.Transport block to detect and apply
the configured proxy (AliveHttpProxy/AliveSocksProxy) and perform TLS
impersonated dialing through that proxy (leveraging the existing proxy dialer
code path used by the original transport), ensuring TLSClientConfig (tlsConfig)
and impersonate.Random are preserved.


jar, _ := cookiejar.New(nil)

httpclient := &http.Client{
Transport: transport,
Transport: roundTripper,
Timeout: time.Duration(options.Timeout*3) * time.Second,
Jar: jar,
CheckRedirect: func(req *http.Request, via []*http.Request) error {
Expand All @@ -94,3 +113,4 @@ func newHttpClient(options *types.Options) (*http.Client, error) {

return httpclient, nil
}

5 changes: 4 additions & 1 deletion pkg/protocols/headless/engine/rules.go
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Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,7 @@ import (

"github.com/go-rod/rod"
"github.com/go-rod/rod/lib/proto"
"github.com/projectdiscovery/gologger"
"github.com/projectdiscovery/nuclei/v3/pkg/protocols/common/protocolstate"
)

Expand Down Expand Up @@ -48,7 +49,9 @@ func (p *Page) routingRuleHandler(httpClient *http.Client) func(ctx *rod.Hijack)
}

// perform the request
_ = ctx.LoadResponse(httpClient, true)
if err := ctx.LoadResponse(httpClient, true); err != nil {
gologger.Verbose().Msgf("headless: failed to load response for %s: %s", ctx.Request.URL(), err)
}

if !p.options.DisableCookie {
// retrieve the updated cookies from the native http client and inject them into the shared cookie jar
Expand Down
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