Affected: koxudaxi datamodel-code-generator

datamodel-code-generator generates Pydantic v2 models, dataclasses, TypedDict, and msgspec.Struct from OpenAPI, JSON Schema, GraphQL, Avro, Protobuf, and raw JSON, YAML, or CSV. Prior to 0.63.0, datamodel-code-generator validates a URL host once in src/datamodel_code_generator/http.py through get_body, _validate_url_for_fetch, and _get_ips_from_host, but then lets httpx resolve the host again for the connection, allowing DNS rebinding to bypass allow_private_network=False and reach internal services. This issue is fixed in version 0.63.0.

Affected: PyPI: datamodel-code-generator

### Summary

`datamodel-code-generator`'s anti-SSRF guard validates the resolved IP of a fetch target once and then lets `httpx` perform its own independent DNS resolution to connect, so the validated address is never pinned. A hostname that resolves to a public IP at validation time and a private IP at connection time (DNS rebinding) bypasses the guard and reaches loopback, link-local cloud-metadata endpoints (`169.254.169.254`), and other internal services — even with the default `allow_private_network=False`. This is a server-side request forgery reachable when the tool fetches an attacker-influenced URL (remote `$ref`, or `--url`).

### Details

In `src/datamodel_code_generator/http.py`, `get_body()` calls `_validate_url_for_fetch()`, which resolves the host via `_get_ips_from_host()` (`socket.getaddrinfo`) and rejects non-global addresses:

```python ips = _get_ips_from_host(host) # resolution #1 (validation) if not ips: return if all(_is_safe_ip(ip) for ip in ips): return raise SchemaFetchError(...) # blocks private/link-local/reserved ```

It then connects with a separate, independent resolution:

```python response = httpx.get(current_url, ...) # resolution #2 (connection) -- NOT pinned to #1 ```

Nothing ties the connection to the IP that passed validation. Between the two resolutions a low-TTL attacker-controlled record can flip from a public address (passes the guard) to a private one (used by the connection). The redirect-handling loop…