youssefnoob003-SindriKit/docs/parsers/env/techniques.md

Env Parser: Techniques

The env subdomain provides runtime introspection of Windows process environment structures without calling Win32 APIs. Today this means PEB access and module list walking; the subdomain is the designated home for future TEB and process-parameter helpers.

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Why a Separate Subdomain

PE parsing interprets file-format structures inside a buffer (headers, directories, sections). Env parsing interprets OS-maintained process state in live memory (PEB, loader lists, thread blocks).

Keeping these separate reflects the code layout:

include/sindri/parsers/
├── pe/          <- buffer-backed PE format parsing
└── env/         <- live process environment structures

NT layout definitions (SND_PEB, SND_LDR_DATA_TABLE_ENTRY, etc.) live in include/sindri/internal/nt/peb.h. Env parsers consume these layouts; they do not duplicate Windows SDK headers to avoid pulling in monitored imports.

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The Process Environment Block (PEB)

The PEB is a user-mode structure describing process-wide state. SindriKit's simplified layout (SND_PEB) exposes the fields relevant to module enumeration and future process-parameter access:

Field	Purpose
BeingDebugged	Anti-debug checks (future env helpers)
Ldr	Pointer to loader data (SND_PEB_LDR_DATA)
ProcessParameters	Command line, image path, environment (future helpers)

Accessing the Local PEB

snd_peb_get_local() reads the current thread's PEB pointer from the CPU segment register:

Architecture	Mechanism	Offset
x64 (Intel/AMD)	__readgsqword	0x60
x86	__readfsdword	0x30
ARM64	__readx18qword	0x60

This is a force-inline in the header — no function call, no import table entry.

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Module List Walking

Loaded modules are tracked in three linked lists inside SND_PEB_LDR_DATA:

InLoadOrderModuleList
InMemoryOrderModuleList      <- used by SindriKit
InInitializationOrderModuleList

SindriKit walks InMemoryOrderModuleList, which matches the order used by most manual mapping and evasion tooling.

Each list entry is an SND_LDR_DATA_TABLE_ENTRY embedded in a LIST_ENTRY. The walker recovers the structure via the standard CONTAINING_RECORD offset:

PSND_LDR_DATA_TABLE_ENTRY entry =
    (PSND_LDR_DATA_TABLE_ENTRY)((BYTE *)list_entry - offsetof(SND_LDR_DATA_TABLE_ENTRY, InMemoryOrderLinks));

Name Matching

Module lookup compares against BaseDllName (short name, e.g. ntdll.dll), not FullDllName (full path). Comparisons are case-insensitive.

String mode (snd_peb_get_module_base): exact length match + snd_wcsnicmp.

Hash mode (snd_peb_get_module_base_hash): copies BaseDllName to a stack buffer, lowercases via snd_hash_wide_lower, compares against the compile-time module hash from sindri_hashes.h.

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Integration with PE Export Resolution

NT and syscall primitives combine env and PE parsers in a two-step pattern:

1. Locate ntdll.dll via snd_peb_get_module_base_hash(SND_HASH_NTDLL_DLL, &ntdll)
2. Resolve exports via snd_pe_get_export_address_hash(..., snd_peb_get_module_base)

The export resolver's forwarder callback is snd_module_resolver_cb — the same wide-name signature as get_module_base on snd_module_api_t. Passing snd_peb_get_module_base wires PEB walking into export forwarder resolution without a separate hash resolver.

KnownDlls bootstrapping bypasses the PEB for the initial clean ntdll copy but subsequent forwarders still hit the PEB-resident module list.

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Integration with Module Primitives

snd_mod_nt wires env parsers directly into the module API table:

snd_module_api_t field	Implementation
get_module_base	snd_peb_get_module_base
get_module_base_hash	snd_peb_get_module_base_hash

This is why module resolution docs reference parsers/env/peb.h rather than a removed primitives/peb module.

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Safety Considerations

• No locking: The loader lists can change if another thread loads a DLL. SindriKit does not acquire the loader lock; callers should avoid concurrent loads during walks.
• Null checks: Both public functions validate out_base and return SND_STATUS_INVALID_PARAMETER on bad input. A missing module returns SND_STATUS_PEB_MODULE_NOT_FOUND.
• Hash collisions: Hash-based lookup assumes compile-time hashes from the project's hash manifest are collision-free for the target module set.

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Future: TEB and Process Parameters

The env subdomain will expand to cover:

• TEB — thread-local storage, stack limits, thread ID (via segment register reads analogous to PEB)
• Process parameters — command line, image path, current directory, environment block via PEB->ProcessParameters

These will follow the same pattern: NT layouts in internal/nt/, public accessors in parsers/env/.