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// Copyright Epic Games, Inc. All Rights Reserved.
#include "httptrafficinspector.h"
#include <zencore/logging.h>
#include <zencore/string.h>
#include <charconv>
namespace zen {
// clang-format off
llhttp_settings_t HttpTrafficInspector::s_RequestSettings = []() {
llhttp_settings_t S;
llhttp_settings_init(&S);
S.on_message_begin = [](llhttp_t*) { return 0; };
S.on_url = [](llhttp_t* p, const char* Data, size_t Len) { return GetThis(p)->OnUrl(Data, Len); };
S.on_status = [](llhttp_t*, const char*, size_t) { return 0; };
S.on_header_field = [](llhttp_t* p, const char* Data, size_t Len) { return GetThis(p)->OnHeaderField(Data, Len); };
S.on_header_value = [](llhttp_t* p, const char* Data, size_t Len) { return GetThis(p)->OnHeaderValue(Data, Len); };
S.on_headers_complete = [](llhttp_t* p) { return GetThis(p)->OnHeadersComplete(); };
S.on_body = [](llhttp_t*, const char*, size_t) { return 0; };
S.on_message_complete = [](llhttp_t* p) { return GetThis(p)->OnMessageComplete(); };
return S;
}();
llhttp_settings_t HttpTrafficInspector::s_ResponseSettings = []() {
llhttp_settings_t S;
llhttp_settings_init(&S);
S.on_message_begin = [](llhttp_t*) { return 0; };
S.on_url = [](llhttp_t*, const char*, size_t) { return 0; };
S.on_status = [](llhttp_t*, const char*, size_t) { return 0; };
S.on_header_field = [](llhttp_t* p, const char* Data, size_t Len) { return GetThis(p)->OnHeaderField(Data, Len); };
S.on_header_value = [](llhttp_t* p, const char* Data, size_t Len) { return GetThis(p)->OnHeaderValue(Data, Len); };
S.on_headers_complete = [](llhttp_t* p) { return GetThis(p)->OnHeadersComplete(); };
S.on_body = [](llhttp_t*, const char*, size_t) { return 0; };
S.on_message_complete = [](llhttp_t* p) { return GetThis(p)->OnMessageComplete(); };
return S;
}();
// clang-format on
HttpTrafficInspector::HttpTrafficInspector(Direction Dir, std::string_view SessionLabel)
: m_Log(logging::Get("proxy.http"))
, m_Direction(Dir)
, m_SessionLabel(SessionLabel)
{
llhttp_settings_t* Settings = (Dir == Direction::Request) ? &s_RequestSettings : &s_ResponseSettings;
llhttp_init(&m_Parser, Dir == Direction::Request ? HTTP_REQUEST : HTTP_RESPONSE, Settings);
m_Parser.data = this;
}
void
HttpTrafficInspector::Inspect(const char* Data, size_t Length)
{
if (m_Disabled)
{
return;
}
llhttp_errno_t Err = llhttp_execute(&m_Parser, Data, Length);
if (Err == HPE_PAUSED_UPGRADE)
{
if (m_Direction == Direction::Request)
{
ZEN_DEBUG("[{}] >> {} {} (upgrade to WebSocket)", m_SessionLabel, m_Method, m_Url);
}
else
{
ZEN_DEBUG("[{}] << {} (upgrade to WebSocket)", m_SessionLabel, m_StatusCode);
}
ResetMessageState();
m_Upgraded.store(true, std::memory_order_relaxed);
m_Disabled = true;
return;
}
if (Err != HPE_OK)
{
ZEN_DEBUG("[{}] non-HTTP traffic detected ({}), disabling inspection", m_SessionLabel, llhttp_errno_name(Err));
m_Disabled = true;
}
}
int
HttpTrafficInspector::OnUrl(const char* Data, size_t Length)
{
m_Url.append(Data, Length);
return 0;
}
int
HttpTrafficInspector::OnHeaderField(const char* Data, size_t Length)
{
m_CurrentHeaderField.assign(Data, Length);
return 0;
}
int
HttpTrafficInspector::OnHeaderValue(const char* Data, size_t Length)
{
if (m_CurrentHeaderField.size() == 14 && StrCaseCompare(m_CurrentHeaderField.c_str(), "Content-Length", 14) == 0)
{
int64_t Value = 0;
std::from_chars(Data, Data + Length, Value);
m_ContentLength = Value;
}
else if (!m_SessionIdCaptured && m_CurrentHeaderField.size() == 10 &&
StrCaseCompare(m_CurrentHeaderField.c_str(), "UE-Session", 10) == 0)
{
Oid Parsed;
if (Oid::TryParse(std::string_view(Data, Length), Parsed))
{
m_SessionId = Parsed;
m_SessionIdCaptured = true;
}
}
m_CurrentHeaderField.clear();
return 0;
}
int
HttpTrafficInspector::OnHeadersComplete()
{
if (m_Direction == Direction::Request)
{
m_Method = llhttp_method_name(static_cast<llhttp_method_t>(llhttp_get_method(&m_Parser)));
}
else
{
m_StatusCode = static_cast<uint16_t>(llhttp_get_status_code(&m_Parser));
}
return 0;
}
int
HttpTrafficInspector::OnMessageComplete()
{
if (m_Direction == Direction::Request)
{
if (m_ContentLength >= 0)
{
ZEN_DEBUG("[{}] >> {} {} (content-length: {})", m_SessionLabel, m_Method, m_Url, m_ContentLength);
}
else
{
ZEN_DEBUG("[{}] >> {} {}", m_SessionLabel, m_Method, m_Url);
}
}
else
{
if (m_ContentLength >= 0)
{
ZEN_DEBUG("[{}] << {} (content-length: {})", m_SessionLabel, m_StatusCode, m_ContentLength);
}
else
{
ZEN_DEBUG("[{}] << {}", m_SessionLabel, m_StatusCode);
}
}
if (m_Observer)
{
m_Observer->OnMessageComplete(m_Direction, m_Method, m_Url, m_StatusCode, m_ContentLength);
}
m_MessageCount.fetch_add(1, std::memory_order_relaxed);
ResetMessageState();
return 0;
}
Oid
HttpTrafficInspector::GetSessionId() const
{
return m_SessionId;
}
bool
HttpTrafficInspector::HasSessionId() const
{
return m_SessionIdCaptured;
}
void
HttpTrafficInspector::ResetMessageState()
{
m_Url.clear();
m_Method.clear();
m_StatusCode = 0;
m_ContentLength = -1;
m_CurrentHeaderField.clear();
}
} // namespace zen
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