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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
http_parser_settings HttpTrafficInspector::s_RequestSettings{
.on_message_begin = [](http_parser*) { return 0; },
.on_url = [](http_parser* p, const char* Data, size_t Len) { return GetThis(p)->OnUrl(Data, Len); },
.on_status = [](http_parser*, const char*, size_t) { return 0; },
.on_header_field = [](http_parser* p, const char* Data, size_t Len) { return GetThis(p)->OnHeaderField(Data, Len); },
.on_header_value = [](http_parser* p, const char* Data, size_t Len) { return GetThis(p)->OnHeaderValue(Data, Len); },
.on_headers_complete = [](http_parser* p) { return GetThis(p)->OnHeadersComplete(); },
.on_body = [](http_parser*, const char*, size_t) { return 0; },
.on_message_complete = [](http_parser* p) { return GetThis(p)->OnMessageComplete(); },
.on_chunk_header{},
.on_chunk_complete{}};
http_parser_settings HttpTrafficInspector::s_ResponseSettings{
.on_message_begin = [](http_parser*) { return 0; },
.on_url = [](http_parser*, const char*, size_t) { return 0; },
.on_status = [](http_parser*, const char*, size_t) { return 0; },
.on_header_field = [](http_parser* p, const char* Data, size_t Len) { return GetThis(p)->OnHeaderField(Data, Len); },
.on_header_value = [](http_parser* p, const char* Data, size_t Len) { return GetThis(p)->OnHeaderValue(Data, Len); },
.on_headers_complete = [](http_parser* p) { return GetThis(p)->OnHeadersComplete(); },
.on_body = [](http_parser*, const char*, size_t) { return 0; },
.on_message_complete = [](http_parser* p) { return GetThis(p)->OnMessageComplete(); },
.on_chunk_header{},
.on_chunk_complete{}};
// clang-format on
HttpTrafficInspector::HttpTrafficInspector(Direction Dir, std::string_view SessionLabel)
: m_Log(logging::Get("proxy.http"))
, m_Direction(Dir)
, m_SessionLabel(SessionLabel)
{
http_parser_init(&m_Parser, Dir == Direction::Request ? HTTP_REQUEST : HTTP_RESPONSE);
m_Parser.data = this;
}
void
HttpTrafficInspector::Inspect(const char* Data, size_t Length)
{
if (m_Disabled)
{
return;
}
http_parser_settings* Settings = (m_Direction == Direction::Request) ? &s_RequestSettings : &s_ResponseSettings;
size_t Parsed = http_parser_execute(&m_Parser, Settings, Data, Length);
if (m_Parser.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;
}
http_errno Error = HTTP_PARSER_ERRNO(&m_Parser);
if (Error != HPE_OK)
{
ZEN_DEBUG("[{}] non-HTTP traffic detected ({}), disabling inspection", m_SessionLabel, http_errno_name(Error));
m_Disabled = true;
}
else if (Parsed != Length)
{
ZEN_DEBUG("[{}] parser consumed {}/{} bytes, disabling inspection", m_SessionLabel, Parsed, Length);
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 = http_method_str(static_cast<http_method>(m_Parser.method));
}
else
{
m_StatusCode = m_Parser.status_code;
}
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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