Merge pull request #236 from aykhans/dependabot/go_modules/github.com/valyala/fasthttp-1.75.0

build(deps): bump github.com/valyala/fasthttp from 1.74.0 to 1.75.0

docs/configuration.md

@@ -177,10 +177,12 @@ The value is a whole number of bytes, with or without a unit: `B`, `KB`, `MB`, `
 
 **Examples:** `1048576`, `10MiB`, `2MB`, `512KiB`
 
-A server can declare a `Content-Length` far larger than it sends, and the body is allocated from that declared length, so without a limit a single response can exhaust memory. A response above the limit fails with `body size exceeds the given limit` and is counted like any other error.
+A server can declare a `Content-Length` far larger than it sends, and the body is allocated from that declared length, so without a limit a single response can exhaust memory. A response above the limit fails with `response body exceeds the body limit` and is counted like any other error.
 
 The limit applies per response in flight, and a declared Content-Length is allocated up to it, so the worst case is a few times the limit times the concurrency. It covers the requests scripts make as well.
 
+A compressed response in a script is decoded first, so the limit covers the decoded size as well as the bytes that arrived. Decoding holds both at once, so a brotli or zstd body peaks at over ten times the limit. Ratios are unbounded, and 106 bytes of brotli can hold 64MiB, so with `0` a tiny download can still exhaust memory.
+
 ## Concurrency
 
 Number of concurrent workers. Must be between 1 and 100,000,000. Defaults to `1`.
@@ -201,7 +203,7 @@ Valid time units: `ns`, `us` (or `µs`), `ms`, `s`, `m`, `h`
 
 Runtime log levels to emit, comma-separated. Valid levels: `info`, `error`. Defaults to `error`.
 
-- `error`: errors that occur while generating or sending a request
+- `error`: errors that occur while generating a request. A request that fails to send is counted in the results instead
 - `info`: every completed response
 
 Leave empty to disable logging entirely.
@@ -232,6 +234,10 @@ Using `none` disables output and reduces memory usage since response statistics
 
 Generate requests without sending them. Useful for testing templates.
 
+A script's own `http` calls are still sent, since a script needs them to build the request you are inspecting. Only the requests sarin generates are held back.
+
+The duration in the results is how long generating each request took, templates and scripts included, so it is a different measurement from the response time a real run reports. A request with neither renders once before the run and reports `0s`.
+
 ## Insecure
 
 Skip TLS certificate verification.
@@ -593,7 +599,7 @@ http(url, opts)
 | `params`       | table/object                | -       | Query parameters, added to any already in the URL                                                      |
 | `cookies`      | table/object                | -       | Cookies, sent as a single `Cookie` header                                                              |
 | `body`         | string                      | `""`    | Request body                                                                                           |
-| `timeout`      | duration string (`"500ms"`) | `30s`   | Request timeout (the `timeout` config does not apply), applied to each hop when redirects are followed |
+| `timeout`      | duration string (`"500ms"`) | `10s`   | Request timeout (the `timeout` config does not apply), applied to each hop when redirects are followed |
 | `insecure`     | boolean                     | `false` | Skip TLS verification (the `insecure` config does not apply)                                           |
 | `maxRedirects` | number                      | `0`     | How many redirects to follow, `0` follows none, maximum 100                                            |
 
@@ -609,9 +615,12 @@ Unknown options and values of the wrong type raise an error.
 | `header(name)` | First value of a header, case-insensitive; `nil`/`null` if missing |
 | `cookie(name)` | Value of a cookie from `Set-Cookie`; `nil`/`null` if missing       |
 | `json()`       | JavaScript only: parses the body as JSON                           |
+| `bytes()`      | JavaScript only: the body as a `Uint8Array`                        |
 
 In Lua, call the helpers as `res:header("name")` or `res.header("name")`.
 
+> **Note:** JavaScript strings hold UTF-16, so `body` replaces bytes that are not valid UTF-8 and `body.length` counts code units rather than bytes. Use `bytes()` for binary responses and for the real byte count. Lua strings keep the bytes as they arrived.
+
 **Behavior:**
 
 - **Runs on every request:** the requests are sent each time `transform` runs, so every main request triggers them. Script globals persist across requests within a worker, so a script can cache a value itself (e.g. `if not token then token = login() end`).
@@ -619,6 +628,7 @@ In Lua, call the helpers as `res:header("name")` or `res.header("name")`.
 - **Status codes:** non-2xx responses are returned normally; check `status` in the script.
 - **Errors:** network failures and timeouts raise a script error. The main request is not sent and the error is counted in the results. Scripts can catch it with `pcall` (Lua) or `try`/`catch` (JavaScript).
 - **Response bodies:** the [Max Response Body](#max-response-body) config bounds these requests too, and a body above it raises an error the script can catch.
+- **Compressed responses:** sarin asks for no encoding, so this only applies when a script sends `Accept-Encoding` itself or the server compresses unasked. A `gzip`, `deflate`, `br` or `zstd` body is then decoded before the script sees it, and `Content-Encoding` and `Content-Length` are both dropped from `headers` because neither describes what the script receives. Anything else is left raw with its header intact: an empty body, `identity`, a `Content-Encoding` sarin does not recognise, and two or more codings at once. A body that fails to decode raises an error the script can catch, though `br` carries no checksum, so damage to a brotli body can go unnoticed.
 - **Only inside `transform`:** `http` works anywhere while `transform` runs, including in helper functions it calls. Calling it at the top level of a script raises an error, because that code also runs during config validation and when each worker starts.
 - **Dry run:** script requests are still sent in dry-run mode.
 - **Not measured:** script requests are not included in the results.

docs/examples.md

@@ -857,7 +857,7 @@ progress: none
 
 ## Runtime Logging
 
-`--log-level` selects which runtime logs Sarin emits (comma-separated `info` and `error`, default `error`). `error` covers request and generation errors, `info` covers every completed response (status, duration, headers, body). Logs appear in the progress log box on an interactive terminal, go to stderr when piped, or go to a file with `--log-file`.
+`--log-level` selects which runtime logs Sarin emits (comma-separated `info` and `error`, default `error`). `error` covers errors raised while generating a request, `info` covers every completed response (status, duration, headers, body). A request that fails to send is counted in the results rather than logged. Logs appear in the progress log box on an interactive terminal, go to stderr when piped, or go to a file with `--log-file`.
 
 **Log responses and errors:**
 
@@ -883,9 +883,8 @@ sarin -U http://example.com -r 1000 -l info -o json > stats.json 2> run.log
 ```yaml
 url: http://example.com
 requests: 1000
-concurrency: 10
-logLevel: info,error
-logFile: ./run.log
+logLevel: info
+output: json
 ```
 
 </details>
@@ -1193,21 +1192,6 @@ js: |
     }
 ```
 
-**Follow redirects and use a slower timeout for a login endpoint:**
-
-```sh
-sarin -U http://example.com/api/me -r 200 -c 5 \
-  -lua 'function transform(req)
-    local res = http("http://example.com/login", {
-      method = "POST",
-      maxRedirects = 5,
-      timeout = "10s",
-    })
-    req.cookies["session"] = res:cookie("session")
-    return req
-  end'
-```
-
 **Keep sending the main request even when the extra call fails:**
 
 A failed `http` call raises an error, which skips the main request and records the failure in the results. Catch it to decide yourself:

docs/templating.md

@@ -2,9 +2,9 @@
 
 Sarin supports Go templates in URL paths, methods, bodies, headers, params, cookies, and values.
 
-> **Note:** Templating in URL host and scheme is not supported. Only the path portion of the URL can contain templates.
+> **Note:** Templating in URL host and scheme is not supported. Only the path and query string of the URL can contain templates.
 
-> **Note:** Template rendering happens before the request is sent. The request timeout (`-T` / `timeout`) only governs the HTTP request itself and starts _after_ templates have finished rendering, so slow template functions (e.g. captcha solvers, remote `file_Read`) cannot cause a request timeout no matter how long they take.
+> **Note:** Template rendering happens before the request is sent. The request timeout (`-T` / `timeout`) only governs the HTTP request itself and starts _after_ templates have finished rendering, so slow template functions (e.g. captcha solvers, remote `file_Read`) cannot cause a request timeout no matter how long they take. Downloads have their own limits: 30 seconds and 64MiB per file.
 
 ## Table of Contents
 
@@ -29,6 +29,7 @@ Sarin supports Go templates in URL paths, methods, bodies, headers, params, cook
     - [Generate](#generate)
     - [Auth](#auth)
     - [Address](#address)
+    - [Airline](#airline)
     - [Game](#game)
     - [Beer](#beer)
     - [Car](#car)
@@ -151,7 +152,7 @@ body: '{{ json_Encode (dict_Str "key1" "value1" "key2" "value2") }}'
 | ------------------------ | ------------------------------------------- | ------------------------------------------------------------------------------- |
 | `time_NowUnix`           | Current Unix timestamp (seconds)            | `{{ time_NowUnix }}` → `1735689600`                                             |
 | `time_NowUnixMilli`      | Current Unix timestamp (milliseconds)       | `{{ time_NowUnixMilli }}` → `1735689600123`                                     |
-| `time_NowRFC3339`        | Current time in RFC3339 format              | `{{ time_NowRFC3339 }}` → `"2026-02-26T21:00:00Z"`                              |
+| `time_NowRFC3339`        | Current time in RFC3339 format              | `{{ time_NowRFC3339 }}` → `"2026-02-26T21:00:00+04:00"` (local time)            |
 | `time_Format(layout, t)` | Format a `time.Time` value with a Go layout | `{{ time_Format "2006-01-02" (strings_ToDate "2024-05-10") }}` → `"2024-05-10"` |
 
 ### Crypto Functions
@@ -165,6 +166,8 @@ body: '{{ json_Encode (dict_Str "key1" "value1" "key2" "value2") }}'
 
 ### Body Functions
 
+> **Note:** These are available in `body` only, not in the URL, headers, params, cookies or values.
+
 | Function                         | Description                                                                                                                                                                                                 | Example                                                             |
 | -------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------- |
 | `body_FormData(pairs ...string)` | Create multipart form data from key-value pairs. Automatically sets the `Content-Type` header. Values starting with `@` are treated as file references (local path or URL). Use `@@` to escape literal `@`. | `{{ body_FormData "field1" "value1" "file" "@/path/to/file.pdf" }}` |
@@ -387,7 +390,7 @@ These functions are powered by [gofakeit](https://github.com/brianvoe/gofakeit)
 | Function                                                                                      | Description                                                 | Example                                               |
 | --------------------------------------------------------------------------------------------- | ----------------------------------------------------------- | ----------------------------------------------------- |
 | `fakeit_Username`                                                                             | Username                                                    | `"Daniel1364"`                                        |
-| `fakeit_Password(upper bool, lower bool, numeric bool, special bool, space bool, length int)` | Generate password with specified character types and length | `{{ fakeit_Password true true true false false 16 }}` |
+| `fakeit_Password(lower bool, upper bool, numeric bool, special bool, space bool, length int)` | Generate password with specified character types and length | `{{ fakeit_Password true true true false false 16 }}` |
 
 ### Address
 

go.mod

@@ -4,14 +4,14 @@ go 1.27.1
 
 require (
 	charm.land/bubbles/v2 v2.2.1
-	charm.land/bubbletea/v2 v2.0.9
+	charm.land/bubbletea/v2 v2.0.10
 	charm.land/glamour/v2 v2.0.1
 	charm.land/lipgloss/v2 v2.0.6
-	github.com/brianvoe/gofakeit/v7 v7.17.0
+	github.com/brianvoe/gofakeit/v7 v7.17.1
 	github.com/charmbracelet/x/term v0.2.2
-	github.com/dop251/goja v0.0.0-20260911104922-fabc3b8078ad
+	github.com/dop251/goja v0.0.0-20261004174310-e21e22eac913
 	github.com/joho/godotenv v1.5.1
-	github.com/valyala/fasthttp v1.74.0
+	github.com/valyala/fasthttp v1.75.0
 	github.com/yuin/gopher-lua v1.1.2
 	go.aykhans.me/utils v1.0.7
 	go.yaml.in/yaml/v4 v4.0.0-rc.6
@@ -23,28 +23,28 @@ require (
 	github.com/aymerick/douceur v0.2.0 // indirect
 	github.com/charmbracelet/colorprofile v0.4.3 // indirect
 	github.com/charmbracelet/harmonica v0.2.0 // indirect
-	github.com/charmbracelet/ultraviolet v0.0.0-20260910203606-6c9e17dc7a16 // indirect
+	github.com/charmbracelet/ultraviolet v0.0.0-20261001125412-878653296cfd // indirect
 	github.com/charmbracelet/x/ansi v0.11.8 // indirect
-	github.com/charmbracelet/x/exp/slice v0.0.0-20260906004030-3986e9119cf9 // indirect
+	github.com/charmbracelet/x/exp/slice v0.1.0 // indirect
 	github.com/charmbracelet/x/termios v0.1.1 // indirect
 	github.com/charmbracelet/x/windows v0.2.2 // indirect
 	github.com/clipperhouse/displaywidth v0.11.0 // indirect
 	github.com/clipperhouse/uax29/v2 v2.7.0 // indirect
 	github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc // indirect
-	github.com/dlclark/regexp2/v2 v2.8.0 // indirect
+	github.com/dlclark/regexp2/v2 v2.8.2 // indirect
 	github.com/go-sourcemap/sourcemap v2.1.4+incompatible // indirect
-	github.com/google/pprof v0.0.0-20260906184651-6331bc6350fe // indirect
+	github.com/google/pprof v0.0.0-20261003200830-ebaad5f31b4d // indirect
 	github.com/gorilla/css v1.0.1 // indirect
-	github.com/klauspost/compress v1.20.0 // indirect
+	github.com/klauspost/compress v1.20.1 // indirect
 	github.com/lucasb-eyer/go-colorful v1.4.1 // indirect
 	github.com/mattn/go-runewidth v0.0.30 // indirect
 	github.com/microcosm-cc/bluemonday v1.0.27 // indirect
-	github.com/molecule-man/go-brrr v1.1.0 // indirect
+	github.com/molecule-man/go-brrr v1.2.0 // indirect
 	github.com/muesli/cancelreader v0.2.2 // indirect
 	github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 // indirect
 	github.com/rivo/uniseg v0.4.7 // indirect
 	github.com/valyala/bytebufferpool v1.0.0 // indirect
-	github.com/xo/terminfo v1.0.0 // indirect
+	github.com/xo/terminfo v1.2.0 // indirect
 	github.com/yuin/goldmark v1.8.6 // indirect
 	github.com/yuin/goldmark-emoji v1.0.6 // indirect
 	golang.org/x/sync v0.23.0 // indirect

go.sum

@@ -1,7 +1,7 @@
 charm.land/bubbles/v2 v2.2.1 h1:Fq1+qm5hV6GkvzLQDhCBpXXE5tLgvh1PRriCLwSvIQU=
 charm.land/bubbles/v2 v2.2.1/go.mod h1:wdMgn+sje1KNXdwFizIWjbf328fIUBxqEmJ/vYPo8yc=
-charm.land/bubbletea/v2 v2.0.9 h1:DpJCMWKgzQK8SJv4zbKKFHAI10ymWy/evClPFk0k0f8=
-charm.land/bubbletea/v2 v2.0.9/go.mod h1:2SkdgoTXluXJHOUwAoRlRXF/28vklb1rFl6GcgV1/ss=
+charm.land/bubbletea/v2 v2.0.10 h1:oolvo20VBpI0PfqE7iFjkZ1bx0WpmXGfnKz5Yldjq5o=
+charm.land/bubbletea/v2 v2.0.10/go.mod h1:QOatcnhOjYIfxzUSTz6raF7Ex4R/rIuHa3SnBdCCpMc=
 charm.land/glamour/v2 v2.0.1 h1:xl+r00A4aJWU0z8fgwKd9fQQ4rsphqGUzuEiXZP5n+c=
 charm.land/glamour/v2 v2.0.1/go.mod h1:jo9z8XqVKPeEFMVdvCRLGk++RyJ3CdUwgNr7EvXLw3k=
 charm.land/lipgloss/v2 v2.0.6 h1:EaGKeuA8FvF+v2BT5VmZd2LoYLaMZJXA5n34th8nCIQ=
@@ -18,20 +18,20 @@ github.com/aymanbagabas/go-udiff v0.4.1 h1:OEIrQ8maEeDBXQDoGCbbTTXYJMYRCRO1fnodZ
 github.com/aymanbagabas/go-udiff v0.4.1/go.mod h1:0L9PGwj20lrtmEMeyw4WKJ/TMyDtvAoK9bf2u/mNo3w=
 github.com/aymerick/douceur v0.2.0 h1:Mv+mAeH1Q+n9Fr+oyamOlAkUNPWPlA8PPGR0QAaYuPk=
 github.com/aymerick/douceur v0.2.0/go.mod h1:wlT5vV2O3h55X9m7iVYN0TBM0NH/MmbLnd30/FjWUq4=
-github.com/brianvoe/gofakeit/v7 v7.17.0 h1:usvHa73vmAjC1JmX4dpZAm1eQkR0riXaxvilScRTFb0=
-github.com/brianvoe/gofakeit/v7 v7.17.0/go.mod h1:QXuPeBw164PJCzCUZVmgpgHJ3Llj49jSLVkKPMtxtxA=
+github.com/brianvoe/gofakeit/v7 v7.17.1 h1:50FLBhTGVJQaj6ysRUu0it8wCdYO2uGM9VfuxI+csEc=
+github.com/brianvoe/gofakeit/v7 v7.17.1/go.mod h1:QXuPeBw164PJCzCUZVmgpgHJ3Llj49jSLVkKPMtxtxA=
 github.com/charmbracelet/colorprofile v0.4.3 h1:QPa1IWkYI+AOB+fE+mg/5/4HRMZcaXex9t5KX76i20Q=
 github.com/charmbracelet/colorprofile v0.4.3/go.mod h1:/zT4BhpD5aGFpqQQqw7a+VtHCzu+zrQtt1zhMt9mR4Q=
 github.com/charmbracelet/harmonica v0.2.0 h1:8NxJWRWg/bzKqqEaaeFNipOu77YR5t8aSwG4pgaUBiQ=
 github.com/charmbracelet/harmonica v0.2.0/go.mod h1:KSri/1RMQOZLbw7AHqgcBycp8pgJnQMYYT8QZRqZ1Ao=
-github.com/charmbracelet/ultraviolet v0.0.0-20260910203606-6c9e17dc7a16 h1:/hSCZO1puetbGd2JikHKN0nAcb2mFevzxJElFoduhaw=
-github.com/charmbracelet/ultraviolet v0.0.0-20260910203606-6c9e17dc7a16/go.mod h1:JFvmQPZh3uAu7PpSZU91bcR0BrIy24HhW+0EsW1uGxE=
+github.com/charmbracelet/ultraviolet v0.0.0-20261001125412-878653296cfd h1:W0HOPGkwRaAmV20plE/f+Rk6Xn+IdR8G0qHsGXcOnF8=
+github.com/charmbracelet/ultraviolet v0.0.0-20261001125412-878653296cfd/go.mod h1:D9SVXVpAsD1pP6xR6BiERbe4+dUU6EW9US1TFrNutGA=
 github.com/charmbracelet/x/ansi v0.11.8 h1:JMFwp0CgDC2+jcOB162HH5k7I3FVbgFSMMYg7dSPBQQ=
 github.com/charmbracelet/x/ansi v0.11.8/go.mod h1:ZNN+3mXny/516oTQPLMPIBeSINvNJJQ8uQXDgbeJxY0=
 github.com/charmbracelet/x/exp/golden v0.0.0-20250806222409-83e3a29d542f h1:pk6gmGpCE7F3FcjaOEKYriCvpmIN4+6OS/RD0vm4uIA=
 github.com/charmbracelet/x/exp/golden v0.0.0-20250806222409-83e3a29d542f/go.mod h1:IfZAMTHB6XkZSeXUqriemErjAWCCzT0LwjKFYCZyw0I=
-github.com/charmbracelet/x/exp/slice v0.0.0-20260906004030-3986e9119cf9 h1:zW96vcZ3zDetccerbN7sS/sCydOE/l/9S+C94pozsaU=
-github.com/charmbracelet/x/exp/slice v0.0.0-20260906004030-3986e9119cf9/go.mod h1:vqEfX6xzqW1pKKZUUiFOKg0OQ7bCh54Q2vR/tserrRA=
+github.com/charmbracelet/x/exp/slice v0.1.0 h1:m46dwuDf3M5SFYMRhxYkLC6z9WnENGVKbcbJlp13/og=
+github.com/charmbracelet/x/exp/slice v0.1.0/go.mod h1:vqEfX6xzqW1pKKZUUiFOKg0OQ7bCh54Q2vR/tserrRA=
 github.com/charmbracelet/x/term v0.2.2 h1:xVRT/S2ZcKdhhOuSP4t5cLi5o+JxklsoEObBSgfgZRk=
 github.com/charmbracelet/x/term v0.2.2/go.mod h1:kF8CY5RddLWrsgVwpw4kAa6TESp6EB5y3uxGLeCqzAI=
 github.com/charmbracelet/x/termios v0.1.1 h1:o3Q2bT8eqzGnGPOYheoYS8eEleT5ZVNYNy8JawjaNZY=
@@ -44,32 +44,32 @@ github.com/clipperhouse/uax29/v2 v2.7.0 h1:+gs4oBZ2gPfVrKPthwbMzWZDaAFPGYK72F0NJ
 github.com/clipperhouse/uax29/v2 v2.7.0/go.mod h1:EFJ2TJMRUaplDxHKj1qAEhCtQPW2tJSwu5BF98AuoVM=
 github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc h1:U9qPSI2PIWSS1VwoXQT9A3Wy9MM3WgvqSxFWenqJduM=
 github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
-github.com/dlclark/regexp2/v2 v2.8.0 h1:CekDhPLGfm+GAJmPVFIG+5dqMIQPkyHJll7BbdneDfw=
-github.com/dlclark/regexp2/v2 v2.8.0/go.mod h1:avUrQvPaLz2DrFNHJF0taWAFFX2C1GMSSoeiqFjcBmU=
-github.com/dop251/goja v0.0.0-20260911104922-fabc3b8078ad h1:5gT9hQ9h8CplLZfAGgFMcoLqQS6I9T2sZwQOCXy8/3s=
-github.com/dop251/goja v0.0.0-20260911104922-fabc3b8078ad/go.mod h1:u8yZRUavu+N4EnFFy6J5fVtjE7lEcZ2YyV2GcBXY9c8=
+github.com/dlclark/regexp2/v2 v2.8.2 h1:uTTe+cxADL4be+dv4DZwsBIEPCQ6RHPlnVuKrtLqSx0=
+github.com/dlclark/regexp2/v2 v2.8.2/go.mod h1:avUrQvPaLz2DrFNHJF0taWAFFX2C1GMSSoeiqFjcBmU=
+github.com/dop251/goja v0.0.0-20261004174310-e21e22eac913 h1:0haZHQSJqA4qFZvnKIRgekXrPo2sQ2oRvFemiNHhcp0=
+github.com/dop251/goja v0.0.0-20261004174310-e21e22eac913/go.mod h1:GrCNKUrVplXZj0juFue0Cj2Xt/eL2Nuu2+y3UTanEo8=
 github.com/go-sourcemap/sourcemap v2.1.4+incompatible h1:a+iTbH5auLKxaNwQFg0B+TCYl6lbukKPc7b5x0n1s6Q=
 github.com/go-sourcemap/sourcemap v2.1.4+incompatible/go.mod h1:F8jJfvm2KbVjc5NqelyYJmf/v5J0dwNLS2mL4sNA1Jg=
 github.com/goccy/go-yaml v1.19.2 h1:PmFC1S6h8ljIz6gMRBopkjP1TVT7xuwrButHID66PoM=
 github.com/goccy/go-yaml v1.19.2/go.mod h1:XBurs7gK8ATbW4ZPGKgcbrY1Br56PdM69F7LkFRi1kA=
-github.com/google/pprof v0.0.0-20260906184651-6331bc6350fe h1:QAinXoAFJdGQYztXn3VpFey7KCwpedbZ/EkzbplQ0cY=
-github.com/google/pprof v0.0.0-20260906184651-6331bc6350fe/go.mod h1:jl5iWTm0/hd5PjEYEOuwAJ57L/CibdZfrqZ5XA5GrCk=
+github.com/google/pprof v0.0.0-20261003200830-ebaad5f31b4d h1:kZK3FQM86gr3cgJHMP7rPn8A3Z75mt+ZaVBoqMlpPF0=
+github.com/google/pprof v0.0.0-20261003200830-ebaad5f31b4d/go.mod h1:jl5iWTm0/hd5PjEYEOuwAJ57L/CibdZfrqZ5XA5GrCk=
 github.com/gorilla/css v1.0.1 h1:ntNaBIghp6JmvWnxbZKANoLyuXTPZ4cAMlo6RyhlbO8=
 github.com/gorilla/css v1.0.1/go.mod h1:BvnYkspnSzMmwRK+b8/xgNPLiIuNZr6vbZBTPQ2A3b0=
 github.com/hexops/gotextdiff v1.0.3 h1:gitA9+qJrrTCsiCl7+kh75nPqQt1cx4ZkudSTLoUqJM=
 github.com/hexops/gotextdiff v1.0.3/go.mod h1:pSWU5MAI3yDq+fZBTazCSJysOMbxWL1BSow5/V2vxeg=
 github.com/joho/godotenv v1.5.1 h1:7eLL/+HRGLY0ldzfGMeQkb7vMd0as4CfYvUVzLqw0N0=
 github.com/joho/godotenv v1.5.1/go.mod h1:f4LDr5Voq0i2e/R5DDNOoa2zzDfwtkZa6DnEwAbqwq4=
-github.com/klauspost/compress v1.20.0 h1:a3C1ke2ohxFymNlb2HWAHjDeKCI90scRskErZkR0ezA=
-github.com/klauspost/compress v1.20.0/go.mod h1:LUdAzn7YLVvxLpc7y3V1m40wESHTgc1422pwwBSKYuI=
+github.com/klauspost/compress v1.20.1 h1:T7kKElXUMXrUJ2E9QhQhxFtcK5rPyLdsGZvdbLMPdiQ=
+github.com/klauspost/compress v1.20.1/go.mod h1:LUdAzn7YLVvxLpc7y3V1m40wESHTgc1422pwwBSKYuI=
 github.com/lucasb-eyer/go-colorful v1.4.1 h1:1EO+WB73+EH8EVbzlrG3KLAfEypQWVHIBqlTf+2hNss=
 github.com/lucasb-eyer/go-colorful v1.4.1/go.mod h1:R4dSotOR9KMtayYi1e77YzuveK+i7ruzyGqttikkLy0=
 github.com/mattn/go-runewidth v0.0.30 h1:+KUuiDA4fF0R1p5FeueHefjDm+GIM+kWfFnDjybOPgk=
 github.com/mattn/go-runewidth v0.0.30/go.mod h1:3qAiGCV4Koz/yuveO58qUefmUTRm8r0IGEXZ9jeHp/8=
 github.com/microcosm-cc/bluemonday v1.0.27 h1:MpEUotklkwCSLeH+Qdx1VJgNqLlpY2KXwXFM08ygZfk=
 github.com/microcosm-cc/bluemonday v1.0.27/go.mod h1:jFi9vgW+H7c3V0lb6nR74Ib/DIB5OBs92Dimizgw2cA=
-github.com/molecule-man/go-brrr v1.1.0 h1:rLBGSXA393y+5ttCBLkW34CHESop5tahrOFxVv/XDEU=
-github.com/molecule-man/go-brrr v1.1.0/go.mod h1:7ybW6/7gA3oKY45jOfVNjSJDtrr6ea4tzbsTkjmQDC4=
+github.com/molecule-man/go-brrr v1.2.0 h1:dOJU45BC3Gc2WXoxAW0rgCAgVuu2gruAOGncfieA0Jw=
+github.com/molecule-man/go-brrr v1.2.0/go.mod h1:7ybW6/7gA3oKY45jOfVNjSJDtrr6ea4tzbsTkjmQDC4=
 github.com/muesli/cancelreader v0.2.2 h1:3I4Kt4BQjOR54NavqnDogx/MIoWBFa0StPA8ELUXHmA=
 github.com/muesli/cancelreader v0.2.2/go.mod h1:3XuTXfFS2VjM+HTLZY9Ak0l6eUKfijIfMUZ4EgX0QYo=
 github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 h1:Jamvg5psRIccs7FGNTlIRMkT8wgtp5eCXdBlqhYGL6U=
@@ -80,10 +80,10 @@ github.com/stretchr/testify v1.11.1 h1:7s2iGBzp5EwR7/aIZr8ao5+dra3wiQyKjjFuvgVKu
 github.com/stretchr/testify v1.11.1/go.mod h1:wZwfW3scLgRK+23gO65QZefKpKQRnfz6sD981Nm4B6U=
 github.com/valyala/bytebufferpool v1.0.0 h1:GqA5TC/0021Y/b9FG4Oi9Mr3q7XYx6KllzawFIhcdPw=
 github.com/valyala/bytebufferpool v1.0.0/go.mod h1:6bBcMArwyJ5K/AmCkWv1jt77kVWyCJ6HpOuEn7z0Csc=
-github.com/valyala/fasthttp v1.74.0 h1:wMS9fnO2QTALozYx5pId2Vi7ZwU/epUkY8i/KPWCHoU=
-github.com/valyala/fasthttp v1.74.0/go.mod h1:3ARmLamUcw7ElxVtC8PXaGzQ6VEuvnetlkrwIklQBSE=
-github.com/xo/terminfo v1.0.0 h1:2ZpYzqWzyyytjk3TP6aJVDhkMAkc99/1xKQdA3TDTBY=
-github.com/xo/terminfo v1.0.0/go.mod h1:RbqR21r5mrJuqunuUZ/Dhy/avygyECGrLceyNeo4LiM=
+github.com/valyala/fasthttp v1.75.0 h1:W3xrvNJHG60j2ZCjxpP8kkB+oPG8kh9/g1n4+3xUwNA=
+github.com/valyala/fasthttp v1.75.0/go.mod h1:JiVkPRZU124PuPsreV/s9dZRgG2lRK7wNEikdQ0Rk4s=
+github.com/xo/terminfo v1.2.0 h1:d0ZTOCpuGE0lwSAOs0zcJjwz3jWQyqcRt9XbGJpCOl4=
+github.com/xo/terminfo v1.2.0/go.mod h1:lGzkSo8Fe7IRh/w+Gqz7n5mDog4FVXCj3gy/DYTBqio=
 github.com/yuin/goldmark v1.8.6 h1:d0VcaP1sx9GkFVkoW+KtggpGi2KZ965i14b0+bDQST4=
 github.com/yuin/goldmark v1.8.6/go.mod h1:ip/1k0VRfGynBgxOz0yCqHrbZXhcjxyuS66Brc7iBKg=
 github.com/yuin/goldmark-emoji v1.0.6 h1:QWfF2FYaXwL74tfGOW5izeiZepUDroDJfWubQI9HTHs=
@@ -94,8 +94,6 @@ go.aykhans.me/utils v1.0.7 h1:ClHXHlWmkjfFlD7+w5BQY29lKCEztxY/yCf543x4hZw=
 go.aykhans.me/utils v1.0.7/go.mod h1:0Jz8GlZLN35cCHLOLx39sazWwEe33bF6SYlSeqzEXoI=
 go.yaml.in/yaml/v4 v4.0.0-rc.6 h1:1h7H1ohdUh93/FyE4YaDa1Zh64K6VVbjF4K6WUxMtH4=
 go.yaml.in/yaml/v4 v4.0.0-rc.6/go.mod h1:aZqd9kCMsGL7AuUv/m/PvWLdg5sjJsZ4oHDEnfPPfY0=
-golang.org/x/exp v0.0.0-20231006140011-7918f672742d h1:jtJma62tbqLibJ5sFQz8bKtEM8rJBtfilJ2qTU199MI=
-golang.org/x/exp v0.0.0-20231006140011-7918f672742d/go.mod h1:ldy0pHrwJyGW56pPQzzkH36rKxoZW1tw7ZJpeKx+hdo=
 golang.org/x/net v0.59.0 h1:5zfYln+w5XCxwrnMMJPufRgNoXEaGxl0wo5GqPXyues=
 golang.org/x/net v0.59.0/go.mod h1:2DA/G1UfVbCpQPeWTmMPGY7Cs2PkBkwu743bVX5PIVg=
 golang.org/x/sync v0.23.0 h1:KameEIfc1IkluZyXWLn39Wd4tURc6GbCiISGiZm2bQk=

internal/config/bytesize.go

@@ -30,19 +30,10 @@ func (size *byteSize) Set(value string) error {
 	return nil
 }
 
-// UnmarshalYAML accepts both a YAML integer and a string with a unit.
+// UnmarshalYAML reads the raw scalar so a size parses the same way here as on the command line.
 func (size *byteSize) UnmarshalYAML(node *yaml.Node) error {
 	if node.Kind != yaml.ScalarNode {
-		return fmt.Errorf("expected a size, but got %s", node.Tag)
-	}
-
-	if node.Tag == "!!int" {
-		var parsed uint64
-		if err := node.Decode(&parsed); err != nil {
-			return types.ErrByteSizeInvalid
-		}
-		*size = byteSize(parsed)
-		return nil
+		return fmt.Errorf("expected a size, but got %s", yamlNodeName(node))
 	}
 
 	return size.Set(node.Value)

internal/config/cli.go

@@ -31,7 +31,7 @@ Flags:
     -w, -log-file          string     Write runtime logs to this file instead of the terminal/stderr
     -p, -progress          string     Progress display (possible values: bar, none) (default '%v')
     -o, -output            string     Output format (possible values: table, json, yaml, none) (default '%v')
-    -z, -dry-run           bool       Run without sending requests (default %v)
+    -z, -dry-run           bool       Run without sending the generated requests (default %v)
 
   Request Config:
     -U, -url               string     Target URL for the request
@@ -145,8 +145,8 @@ func (parser ConfigCLIParser) Parse() (*Config, error) {
 		flagSet.StringVar(&output, "output", "", "Output format (possible values: table, json, yaml, none)")
 		flagSet.StringVar(&output, "o", "", "Output format (possible values: table, json, yaml, none)")
 
-		flagSet.BoolVar(&dryRun, "dry-run", false, "Run without sending requests")
-		flagSet.BoolVar(&dryRun, "z", false, "Run without sending requests")
+		flagSet.BoolVar(&dryRun, "dry-run", false, "Run without sending the generated requests")
+		flagSet.BoolVar(&dryRun, "z", false, "Run without sending the generated requests")
 
 		// Request config
 		flagSet.StringVar(&urlInput, "url", "", "Target URL for the request")

internal/config/config.go

@@ -652,12 +652,19 @@ func ReadAllConfigs() *Config {
 
 	for _, configFile := range append(envConfig.Files, cliConf.Files...) {
 		fileConfig, err := parseConfigFile(configFile, 10)
+
+		// A nested configFile fails under its own name, not the one given on the command line.
+		path := configFile.Path()
+		if configFileErr, ok := errors.AsType[types.ConfigFileError](err); ok {
+			path = configFileErr.Path
+		}
+
 		_ = utilsErr.MustHandle(err,
 			utilsErr.OnType(func(err types.ConfigFileReadError) error {
 				cliParser.PrintHelp()
 				fmt.Fprint(os.Stderr, lipgloss.Sprintln(
 					StyleYellow.Render(
-						fmt.Sprintf("\nFailed to read config file (%s): ", configFile.Path())+err.Error(),
+						fmt.Sprintf("\nFailed to read config file (%s): ", path)+err.Error(),
 					),
 				))
 				os.Exit(1)
@@ -666,14 +673,14 @@ func ReadAllConfigs() *Config {
 			utilsErr.OnType(func(err types.UnmarshalError) error {
 				fmt.Fprint(os.Stderr, lipgloss.Sprintln(
 					StyleYellow.Render(
-						fmt.Sprintf("\nFailed to parse config file (%s): ", configFile.Path())+err.Error(),
+						fmt.Sprintf("\nFailed to parse config file (%s): ", path)+err.Error(),
 					),
 				))
 				os.Exit(1)
 				return nil
 			}),
 			utilsErr.OnType(func(err types.FieldParseErrors) error {
-				printParseErrors(fmt.Sprintf("CONFIG FILE '%s'", configFile.Path()), err.Errors...)
+				printParseErrors(fmt.Sprintf("CONFIG FILE '%s'", path), err.Errors...)
 				os.Exit(1)
 				return nil
 			}),
@@ -689,7 +696,7 @@ func ReadAllConfigs() *Config {
 
 // parseConfigFile recursively parses a config file and its nested files up to maxDepth levels.
 // Returns the merged configuration or an error if parsing fails.
-// It can return the following errors:
+// It can return the following errors, each wrapped in a types.ConfigFileError naming the file:
 // - types.ConfigFileReadError
 // - types.UnmarshalError
 // - types.FieldParseErrors
@@ -697,7 +704,7 @@ func parseConfigFile(configFile types.ConfigFile, maxDepth int) (*Config, error)
 	configFileParser := NewConfigFileParser(configFile)
 	fileConfig, err := configFileParser.Parse()
 	if err != nil {
-		return nil, err
+		return nil, types.NewConfigFileError(configFile.Path(), err)
 	}
 
 	if maxDepth <= 0 {

internal/config/file.go

@@ -1,13 +1,17 @@
 package config
 
 import (
+	"bytes"
 	"context"
+	"errors"
 	"fmt"
 	"io"
 	"net/http"
 	"net/url"
 	"os"
 	"path/filepath"
+	"reflect"
+	"strconv"
 	"strings"
 	"time"
 
@@ -134,7 +138,7 @@ func (ss *stringOrSliceField) UnmarshalYAML(node *yaml.Node) error {
 		*ss = slice
 		return nil
 	default:
-		return fmt.Errorf("expected a string or a sequence of strings, but got %v", node.Kind)
+		return fmt.Errorf("expected a string or a sequence of strings, but got %s", yamlNodeName(node))
 	}
 }
 
@@ -155,7 +159,7 @@ func (kv *keyValuesField) UnmarshalYAML(node *yaml.Node) error {
 		// Handle sequence of maps: [{key1: value1}, {key2: value2}]
 		for _, item := range node.Content {
 			if item.Kind != yaml.MappingNode {
-				return fmt.Errorf("expected a mapping in sequence, but got %v", item.Kind)
+				return fmt.Errorf("expected a mapping in sequence, but got %s", yamlNodeName(item))
 			}
 			if err := kv.unmarshalMapping(item); err != nil {
 				return err
@@ -163,7 +167,7 @@ func (kv *keyValuesField) UnmarshalYAML(node *yaml.Node) error {
 		}
 		return nil
 	default:
-		return fmt.Errorf("expected a mapping or sequence of mappings, but got %v", node.Kind)
+		return fmt.Errorf("expected a mapping or sequence of mappings, but got %s", yamlNodeName(node))
 	}
 }
 
@@ -174,7 +178,7 @@ func (kv *keyValuesField) unmarshalMapping(node *yaml.Node) error {
 		valueNode := node.Content[i+1]
 
 		if keyNode.Kind != yaml.ScalarNode {
-			return fmt.Errorf("expected a string key, but got %v", keyNode.Kind)
+			return fmt.Errorf("expected a string key, but got %s", yamlNodeName(keyNode))
 		}
 
 		key := keyNode.Value
@@ -186,12 +190,12 @@ func (kv *keyValuesField) unmarshalMapping(node *yaml.Node) error {
 		case yaml.SequenceNode:
 			for _, v := range valueNode.Content {
 				if v.Kind != yaml.ScalarNode {
-					return fmt.Errorf("expected string values in array for key %q, but got %v", key, v.Kind)
+					return fmt.Errorf("expected string values in array for key %q, but got %s", key, yamlNodeName(v))
 				}
 				values = append(values, v.Value)
 			}
 		default:
-			return fmt.Errorf("expected a string or array of strings for key %q, but got %v", key, valueNode.Kind)
+			return fmt.Errorf("expected a string or array of strings for key %q, but got %s", key, yamlNodeName(valueNode))
 		}
 
 		*kv = append(*kv, types.KeyValue[string, []string]{Key: key, Value: values})
@@ -235,9 +239,26 @@ func (parser ConfigFileParser) ParseYAML(data []byte) (*Config, error) {
 		parsedData = &configYAML{}
 	)
 
-	err := yaml.Unmarshal(data, &parsedData)
-	if err != nil {
-		return nil, types.NewUnmarshalError(err)
+	decoder := yaml.NewDecoder(bytes.NewReader(data))
+	decoder.KnownFields(true)
+	// The decoder returns a bare io.EOF for an empty file, errors.Is would also match a wrapped one.
+	if err := decoder.Decode(parsedData); err != nil && err != io.EOF { //nolint:errorlint
+		return nil, types.NewUnmarshalError(yamlError(err))
+	}
+
+	// Decode reads one document, so anything after the first "---" would be dropped silently.
+	for {
+		var next yaml.Node
+		err := decoder.Decode(&next)
+		if err == io.EOF { //nolint:errorlint
+			break
+		}
+		if err != nil {
+			return nil, types.NewUnmarshalError(yamlError(err))
+		}
+		if !isEmptyDocument(&next) {
+			return nil, types.NewUnmarshalError(types.ErrYAMLMultipleDocuments)
+		}
 	}
 
 	var fieldParseErrors []types.FieldParseError
@@ -312,3 +333,186 @@ func (parser ConfigFileParser) ParseYAML(data []byte) (*Config, error) {
 
 	return config, nil
 }
+
+// configYAMLTypeName is the Go type name the yaml package puts in its messages.
+var configYAMLTypeName = reflect.TypeFor[configYAML]().String()
+
+// isEmptyDocument reports whether a document holds nothing, which a trailing "---" produces.
+// A null tag alone is not enough, since a user can hang it on a mapping that does hold content.
+func isEmptyDocument(node *yaml.Node) bool {
+	if len(node.Content) == 0 {
+		return true
+	}
+	root := node.Content[0]
+	return root.Kind == yaml.ScalarNode && root.Tag == "!!null"
+}
+
+// yamlError rewrites yaml decode errors so they read like config file errors.
+// Errors from building the config arrive collected, everything earlier arrives on its own.
+func yamlError(err error) error {
+	var loadErrors *yaml.LoadErrors
+	if errors.As(err, &loadErrors) && len(loadErrors.Errors) > 0 {
+		var builder strings.Builder
+		for i, loadError := range loadErrors.Errors {
+			if i > 0 {
+				builder.WriteString("\n")
+			}
+			builder.WriteString(yamlErrorText(loadError))
+		}
+		return errors.New(builder.String())
+	}
+
+	if loadError, ok := errors.AsType[*yaml.LoadError](err); ok {
+		return errors.New(yamlErrorText(loadError))
+	}
+
+	return err
+}
+
+// yamlErrorText renders one error as "line 3: while scanning a plain scalar: found a tab character".
+// The mark is where reading gave up and the context mark starts the construct that broke.
+func yamlErrorText(loadError *yaml.LoadError) string {
+	var builder strings.Builder
+	if loadError.Mark.Line > 0 {
+		fmt.Fprintf(&builder, "line %d: ", loadError.Mark.Line)
+	}
+	if loadError.ContextMsg != "" {
+		builder.WriteString(loadError.ContextMsg + ": ")
+	}
+	builder.WriteString(yamlErrorMessage(loadError.Message))
+
+	start := loadError.ContextMark
+	if loadError.ContextMsg != "" && start.Line > 0 && start.Line != loadError.Mark.Line {
+		fmt.Fprintf(&builder, " (started at line %d)", start.Line)
+	}
+
+	return builder.String()
+}
+
+// yamlTypeNames maps the Go types and YAML tags the yaml package prints to words a user knows.
+var yamlTypeNames = map[string]string{
+	"!!str":            "text",
+	"!!int":            "a number",
+	"!!float":          "a number",
+	"!!bool":           "true or false",
+	"!!seq":            "a list",
+	"!!map":            "a mapping",
+	"!!null":           "an empty value",
+	"!!timestamp":      "a date",
+	"!!binary":         "binary data",
+	"string":           "text",
+	"bool":             "true or false",
+	"uint":             "a whole number of 0 or more",
+	"uint64":           "a whole number of 0 or more",
+	"time.Duration":    "a duration such as 10s",
+	configYAMLTypeName: "a mapping of config keys",
+}
+
+// yamlNodeName names what a node holds, so an error can say "a list" instead of a kind number.
+// A tag that contradicts the shape is kept, since the shape alone would read as a contradiction.
+func yamlNodeName(node *yaml.Node) string {
+	if name, ok := yamlTypeNames[node.Tag]; ok && yamlTagKind(node.Tag) == node.Kind {
+		return name
+	}
+	if node.Tag == "" {
+		return yamlKindName(node.Kind)
+	}
+	return yamlKindName(node.Kind) + " tagged " + node.Tag
+}
+
+// yamlTagKind returns the node shape a tag belongs on, so a mismatch can be spotted.
+func yamlTagKind(tag string) yaml.Kind {
+	switch tag {
+	case "!!seq":
+		return yaml.SequenceNode
+	case "!!map":
+		return yaml.MappingNode
+	default:
+		return yaml.ScalarNode
+	}
+}
+
+// yamlKindName names a node by its shape, for when its tag says nothing a user would know.
+func yamlKindName(kind yaml.Kind) string {
+	switch kind {
+	case yaml.SequenceNode:
+		return "a list"
+	case yaml.MappingNode:
+		return "a mapping"
+	case yaml.AliasNode:
+		return "an alias"
+	default:
+		return "a value"
+	}
+}
+
+// yamlErrorMessage turns "field x not found in type config.configYAML" into "unknown key "x"".
+func yamlErrorMessage(message string) string {
+	if field, ok := strings.CutSuffix(message, " not found in type "+configYAMLTypeName); ok {
+		if name, ok := strings.CutPrefix(field, "field "); ok {
+			return fmt.Sprintf("unknown key %q", name)
+		}
+	}
+
+	// The user controls the value, so the rightmost separator is the only one that is ours.
+	// After "as a" comes the tag the user wrote, after "into" comes the type the key accepts.
+	if names, ok := strings.CutPrefix(message, "cannot construct "); ok {
+		at, width, tagged := -1, 0, false
+		for index, separator := range []string{" into ", " as a "} {
+			if found := strings.LastIndex(names, separator); found > at {
+				at, width, tagged = found, len(separator), index == 1
+			}
+		}
+		if at >= 0 {
+			got, want := yamlGotName(names[:at]), yamlWantedName(names[at+width:])
+			if tagged {
+				return fmt.Sprintf("%s is not %s", got, want)
+			}
+			return fmt.Sprintf("expected %s, but got %s", want, got)
+		}
+	}
+
+	return strings.ReplaceAll(message, configYAMLTypeName, "the config file")
+}
+
+// yamlWantedName names what a key accepts, which the yaml package prints as a Go type.
+func yamlWantedName(text string) string {
+	if name, ok := yamlTypeNames[text]; ok {
+		return name
+	}
+	return text
+}
+
+// yamlGotName names what the file held, which the yaml package prints as a tag and sometimes a value.
+// A tag the user would not know stays in the text, since without it the message reads as nonsense.
+func yamlGotName(text string) string {
+	// A collection tag carries no backticks, so a scalar wearing one arrives glued to it.
+	for _, tag := range []string{"!!seq", "!!map"} {
+		if value, ok := strings.CutPrefix(text, tag); ok && value != "" {
+			return yamlValueText(value) + " tagged " + tag
+		}
+	}
+
+	tag, value, _ := strings.Cut(text, " ")
+	value = strings.TrimSuffix(strings.TrimPrefix(value, "`"), "`")
+
+	name, known := yamlTypeNames[tag]
+	switch {
+	case known && value != "":
+		return yamlValueText(value)
+	case known:
+		return name
+	case value != "":
+		return yamlValueText(value) + " tagged " + tag
+	default:
+		return "a value tagged " + tag
+	}
+}
+
+// yamlValueText quotes a value, saying so when the yaml package shortened it to seven characters.
+func yamlValueText(value string) string {
+	if start, ok := strings.CutSuffix(value, "..."); ok && len(start) == 7 {
+		return "a value starting with " + strconv.Quote(start)
+	}
+	return strconv.Quote(value)
+}

internal/sarin/client.go

@@ -19,6 +19,90 @@ import (
 // clientIndexGenerator returns the index of the host client (and proxy) to use next.
 type clientIndexGenerator func() int
 
+// preferIPv4Resolver hides a host's IPv6 addresses whenever it also has IPv4 ones.
+type preferIPv4Resolver struct{}
+
+func (preferIPv4Resolver) LookupIPAddr(ctx context.Context, host string) ([]net.IPAddr, error) {
+	return lookupPreferred(ctx, host, true)
+}
+
+// preferIPv6Resolver is the mirror of preferIPv4Resolver, used for the fallback dial.
+type preferIPv6Resolver struct{}
+
+func (preferIPv6Resolver) LookupIPAddr(ctx context.Context, host string) ([]net.IPAddr, error) {
+	return lookupPreferred(ctx, host, false)
+}
+
+// lookupPreferred resolves host and keeps only the wanted family, unless that family is absent.
+func lookupPreferred(ctx context.Context, host string, wantIPv4 bool) ([]net.IPAddr, error) {
+	ips, err := net.DefaultResolver.LookupIPAddr(ctx, host)
+	if err != nil {
+		return nil, err
+	}
+
+	preferred := make([]net.IPAddr, 0, len(ips))
+	for _, ip := range ips {
+		if (ip.IP.To4() != nil) == wantIPv4 {
+			preferred = append(preferred, ip)
+		}
+	}
+	if len(preferred) > 0 {
+		return preferred, nil
+	}
+	return ips, nil
+}
+
+// preferIPv4DialTimeoutShare leaves half the timeout for the IPv6 retry.
+const preferIPv4DialTimeoutShare = 2
+
+// preferIPv4Dialer dials over IPv4 and retries over IPv6 alone when that fails.
+type preferIPv4Dialer struct {
+	ipv4 *fasthttp.TCPDialer
+	ipv6 *fasthttp.TCPDialer
+}
+
+// dialerConcurrency matches the limit on fasthttp own package-level dialer.
+const dialerConcurrency = 1000
+
+// dialer is shared so all clients use one DNS cache.
+var dialer = &preferIPv4Dialer{
+	ipv4: &fasthttp.TCPDialer{Resolver: preferIPv4Resolver{}, Concurrency: dialerConcurrency},
+	ipv6: &fasthttp.TCPDialer{Resolver: preferIPv6Resolver{}, Concurrency: dialerConcurrency},
+}
+
+// DialTimeout dials addr, which must carry a port.
+func (d *preferIPv4Dialer) DialTimeout(addr string, timeout time.Duration) (net.Conn, error) {
+	// fasthttp passes 0 from its pooled dial path.
+	if timeout <= 0 {
+		timeout = fasthttp.DefaultDialTimeout
+	}
+	deadline := time.Now().Add(timeout)
+
+	conn, err := d.ipv4.DialDualStackTimeout(addr, timeout/preferIPv4DialTimeoutShare)
+	if err == nil {
+		return conn, nil
+	}
+
+	remaining := time.Until(deadline)
+	if remaining <= 0 {
+		return nil, err
+	}
+
+	conn, fallbackErr := d.ipv6.DialDualStackTimeout(addr, remaining)
+	if fallbackErr != nil {
+		// Report the IPv4 error, not the fallback one.
+		return nil, err
+	}
+	return conn, nil
+}
+
+// dialFunc fills in the default port, which fasthttp skips for a custom dial func.
+func (d *preferIPv4Dialer) dialFunc(isTLS bool) fasthttp.DialFuncWithTimeout {
+	return func(addr string, timeout time.Duration) (net.Conn, error) {
+		return d.DialTimeout(fasthttp.AddMissingPort(addr, isTLS), timeout)
+	}
+}
+
 // NewHostClients creates a list of fasthttp.HostClient instances for the given proxies.
 // If no proxies are provided, a single client without a proxy is returned.
 // It can return the following errors:
@@ -60,6 +144,8 @@ func NewHostClients(
 				WriteTimeout:                  timeout,
 				ReadTimeout:                   timeout,
 				MaxResponseBodySize:           safeUint64ToInt(maxResponseBody),
+				MaxIdemponentCallAttempts:     1,
+				ReadBufferSize:                64 << 10, // 64 KiB
 				DisableHeaderNamesNormalizing: true,
 				DisablePathNormalizing:        true,
 				NoDefaultUserAgentHeader:      true,
@@ -71,9 +157,9 @@ func NewHostClients(
 	}
 
 	client := &fasthttp.HostClient{
-		MaxConns:      safeUintToInt(maxConns),
-		IsTLS:         isTLS,
-		DialDualStack: true,
+		MaxConns:    safeUintToInt(maxConns),
+		IsTLS:       isTLS,
+		DialTimeout: dialer.dialFunc(isTLS),
 		TLSConfig: &tls.Config{
 			InsecureSkipVerify: skipVerify, //nolint:gosec
 		},
@@ -83,6 +169,8 @@ func NewHostClients(
 		WriteTimeout:                  timeout,
 		ReadTimeout:                   timeout,
 		MaxResponseBodySize:           safeUint64ToInt(maxResponseBody),
+		MaxIdemponentCallAttempts:     1,
+		ReadBufferSize:                64 << 10, // 64 KiB
 		DisableHeaderNamesNormalizing: true,
 		DisablePathNormalizing:        true,
 		NoDefaultUserAgentHeader:      true,
@@ -252,7 +340,7 @@ func fasthttpConnectDialer(proxyURL *url.URL, useTLS bool) fasthttp.DialFuncWith
 	return func(addr string, timeout time.Duration) (net.Conn, error) {
 		// Establish TCP connection to proxy with timeout
 		start := time.Now()
-		conn, err := fasthttp.DialDualStackTimeout(proxyAddr, timeout)
+		conn, err := dialer.DialTimeout(proxyAddr, timeout)
 		if err != nil {
 			return nil, types.NewProxyDialError(proxyStr, err)
 		}

internal/sarin/runner.go

@@ -311,7 +311,7 @@ func NewSarin(
 		logFile:           logFile,
 		hostClients:       hostClients,
 		scriptHTTPClients: scriptHTTPClients,
-		fileCache:         NewFileCache(time.Second * 10),
+		fileCache:         NewFileCache(time.Second * 30),
 		scriptChain:       scriptChain,
 	}
 

internal/sarin/scripthttp.go

@@ -1,6 +1,7 @@
 package sarin
 
 import (
+	"compress/zlib"
 	"context"
 	"crypto/tls"
 	"errors"
@@ -13,15 +14,16 @@ import (
 	"go.aykhans.me/sarin/internal/types"
 )
 
-// scriptHTTPDefaultTimeout is the default timeout for script requests, independent of -T.
-const scriptHTTPDefaultTimeout = 30 * time.Second
+// scriptHTTPDefaultTimeout is the default timeout for script requests.
+const scriptHTTPDefaultTimeout = 10 * time.Second
 
 // scriptHTTPClient sends scripts' http.* requests. It is safe for concurrent use.
 type scriptHTTPClient struct {
-	ctx            context.Context //nolint:containedctx
-	client         *fasthttp.Client
-	insecureClient *fasthttp.Client
-	defaultTimeout time.Duration
+	ctx             context.Context //nolint:containedctx
+	client          *fasthttp.Client
+	insecureClient  *fasthttp.Client
+	defaultTimeout  time.Duration
+	maxResponseBody int
 }
 
 var _ script.HTTPDoer = (*scriptHTTPClient)(nil)
@@ -31,7 +33,7 @@ var _ script.HTTPDoer = (*scriptHTTPClient)(nil)
 //   - types.ProxyDialError
 func newScriptHTTPClients(ctx context.Context, proxies []url.URL, maxConns uint, maxResponseBody uint64) ([]*scriptHTTPClient, error) {
 	if len(proxies) == 0 {
-		return []*scriptHTTPClient{newScriptHTTPClient(ctx, fasthttp.DialDualStackTimeout, scriptHTTPDefaultTimeout, maxConns, maxResponseBody)}, nil
+		return []*scriptHTTPClient{newScriptHTTPClient(ctx, dialer.DialTimeout, scriptHTTPDefaultTimeout, maxConns, maxResponseBody)}, nil
 	}
 
 	clients := make([]*scriptHTTPClient, 0, len(proxies))
@@ -56,9 +58,11 @@ func newScriptHTTPClient(
 		// Read and write timeouts stay unset because they would cap the per-call timeout,
 		// so dialWithDeadline is what bounds the TLS handshake.
 		return &fasthttp.Client{
-			DialTimeout:         dialWithDeadline(dial),
-			MaxConnsPerHost:     safeUintToInt(maxConns),
-			MaxResponseBodySize: safeUint64ToInt(maxResponseBody),
+			DialTimeout:               dialWithDeadline(dial),
+			MaxConnsPerHost:           safeUintToInt(maxConns),
+			MaxResponseBodySize:       safeUint64ToInt(maxResponseBody),
+			MaxIdemponentCallAttempts: 1,
+			ReadBufferSize:            64 << 10, // 64 KiB
 			TLSConfig: &tls.Config{
 				InsecureSkipVerify: insecure, //nolint:gosec
 			},
@@ -69,10 +73,11 @@ func newScriptHTTPClient(
 	}
 
 	return &scriptHTTPClient{
-		ctx:            ctx,
-		client:         newClient(false),
-		insecureClient: newClient(true),
-		defaultTimeout: defaultTimeout,
+		ctx:             ctx,
+		client:          newClient(false),
+		insecureClient:  newClient(true),
+		defaultTimeout:  defaultTimeout,
+		maxResponseBody: safeUint64ToInt(maxResponseBody),
 	}
 }
 
@@ -159,12 +164,15 @@ func (c *scriptHTTPClient) Do(r *script.HTTPRequest) (*script.HTTPResponse, erro
 	}
 	if err != nil {
 		if errors.Is(err, fasthttp.ErrBodyTooLarge) {
-			err = types.ErrScriptHTTPBodyTooLarge
+			err = types.ErrResponseBodyTooLarge
 		}
 		return nil, types.NewScriptHTTPRequestError(r.Method, r.URL, err)
 	}
 
-	body := resp.Body()
+	body, err := decodeResponseBody(resp, c.maxResponseBody)
+	if err != nil {
+		return nil, types.NewScriptHTTPRequestError(r.Method, r.URL, err)
+	}
 
 	return &script.HTTPResponse{
 		Status:  resp.StatusCode(),
@@ -172,3 +180,31 @@ func (c *scriptHTTPClient) Do(r *script.HTTPRequest) (*script.HTTPResponse, erro
 		Body:    string(body),
 	}, nil
 }
+
+// decodeResponseBody decodes a body the server compressed, since scripts read it as text.
+// The limit covers the decoded size, which is what a compression bomb inflates to.
+// An empty body is left alone because the decoders reject zero bytes, and a HEAD or a 304
+// carries the encoding with no body. A coding fasthttp does not decode, and the bare
+// deflate stream some servers send without a zlib header, are left raw for the script.
+func decodeResponseBody(resp *fasthttp.Response, maxResponseBody int) ([]byte, error) {
+	if len(resp.Header.ContentEncoding()) == 0 || len(resp.Body()) == 0 {
+		return resp.Body(), nil
+	}
+
+	decoded, err := resp.BodyUncompressedWithLimit(maxResponseBody)
+	if errors.Is(err, fasthttp.ErrContentEncodingUnsupported) || errors.Is(err, zlib.ErrHeader) {
+		return resp.Body(), nil
+	}
+	if err != nil {
+		if errors.Is(err, fasthttp.ErrBodyTooLarge) {
+			err = types.ErrResponseBodyTooLarge
+		}
+		return nil, err
+	}
+
+	// Neither header describes the decoded body, so both go, as net/http does on a gunzip.
+	resp.Header.SetContentEncoding("")
+	resp.Header.Del(fasthttp.HeaderContentLength)
+
+	return decoded, nil
+}

internal/sarin/worker.go

@@ -35,6 +35,10 @@ func statusCodeToString(code int) string {
 
 // responseErrorKey drops the local address, whose port would mint a stats entry per connection.
 func responseErrorKey(err error) string {
+	if errors.Is(err, fasthttp.ErrBodyTooLarge) {
+		return types.ErrResponseBodyTooLarge.Error()
+	}
+
 	message := err.Error()
 
 	var opErr *net.OpError

internal/script/js.go

@@ -2,6 +2,8 @@ package script
 
 import (
 	"errors"
+	"fmt"
+	"reflect"
 	"strconv"
 
 	"github.com/dop251/goja"
@@ -18,6 +20,9 @@ type JsEngine struct {
 	http             httpBridge
 }
 
+// promiseType is what a transform returns when it is declared async or as a generator.
+var promiseType = reflect.TypeFor[*goja.Promise]()
+
 // NewJsEngine creates a new JavaScript script engine with the given script content.
 // The script must define a global `transform` function that takes a request object
 // and returns the modified request object.
@@ -42,8 +47,7 @@ func NewJsEngine(scriptContent string) (*JsEngine, error) {
 	}
 
 	// Execute the script to define the transform function
-	_, err := vm.RunString(scriptContent)
-	if err != nil {
+	if _, err := vm.RunString(scriptContent); err != nil {
 		return nil, types.NewScriptExecutionError("JavaScript", engine.exceptionError(err))
 	}
 
@@ -58,6 +62,12 @@ func NewJsEngine(scriptContent string) (*JsEngine, error) {
 		return nil, types.NewScriptExecutionError("JavaScript", errors.New("'transform' must be a function"))
 	}
 
+	// A generator returns an iterator, which is an ordinary object to Go, so the
+	// call cannot tell it apart and the declaration is the only thing left to read.
+	if isGeneratorFunction(vm, transformVal) {
+		return nil, types.ErrScriptTransformAsync
+	}
+
 	engine.transform = transform
 
 	return engine, nil
@@ -84,6 +94,13 @@ func (e *JsEngine) Transform(req *RequestData) error {
 		return types.NewScriptExecutionError("JavaScript", e.exceptionError(err))
 	}
 
+	// An async or generator transform returns a promise nothing ever awaits, and a promise
+	// carries none of the request fields, so the request would go out untransformed.
+	// ExportType reads the type alone, while Export would run every getter on the result.
+	if result.ExportType() == promiseType {
+		return types.ErrScriptTransformAsync
+	}
+
 	// Update RequestData from the returned object
 	if err := e.objectToRequestData(result, req); err != nil {
 		return types.NewScriptExecutionError("JavaScript", err)
@@ -144,37 +161,70 @@ func (e *JsEngine) objectToRequestData(val goja.Value, req *RequestData) error {
 		return types.ErrScriptTransformReturnObject
 	}
 
-	// Method
-	if v := obj.Get("method"); v != nil && !goja.IsUndefined(v) {
-		req.Method = v.String()
+	// Reading a field runs the script's own getters and toString, which throw as a Go
+	// panic outside goja's execution context, so the whole read runs inside Try.
+	var fieldErr error
+	if thrown := e.runtime.Try(func() {
+		// Method
+		if v := obj.Get("method"); v != nil && !goja.IsUndefined(v) && !goja.IsNull(v) {
+			req.Method = v.String()
+		}
+
+		// Path
+		if v := obj.Get("path"); v != nil && !goja.IsUndefined(v) && !goja.IsNull(v) {
+			req.Path = v.String()
+		}
+
+		// Body
+		if v := obj.Get("body"); v != nil && !goja.IsUndefined(v) && !goja.IsNull(v) {
+			req.Body = v.String()
+		}
+
+		// Headers
+		if v := obj.Get("headers"); v != nil && !goja.IsUndefined(v) && !goja.IsNull(v) {
+			values, err := objectField("headers", v)
+			if err != nil {
+				fieldErr = err
+				return
+			}
+			req.Headers = e.objectToStringSliceMap(values)
+		}
+
+		// Params
+		if v := obj.Get("params"); v != nil && !goja.IsUndefined(v) && !goja.IsNull(v) {
+			values, err := objectField("params", v)
+			if err != nil {
+				fieldErr = err
+				return
+			}
+			req.Params = e.objectToStringSliceMap(values)
+		}
+
+		// Cookies
+		if v := obj.Get("cookies"); v != nil && !goja.IsUndefined(v) && !goja.IsNull(v) {
+			values, err := objectField("cookies", v)
+			if err != nil {
+				fieldErr = err
+				return
+			}
+			req.Cookies = e.objectToStringSliceMap(values)
+		}
+	}); thrown != nil {
+		return e.exceptionError(thrown)
 	}
 
-	// Path
-	if v := obj.Get("path"); v != nil && !goja.IsUndefined(v) {
-		req.Path = v.String()
-	}
+	return fieldErr
+}
 
-	// Body
-	if v := obj.Get("body"); v != nil && !goja.IsUndefined(v) {
-		req.Body = v.String()
+// objectField rejects anything that is not a plain object, since reading keys off an
+// array or a boxed string yields headers named after indexes and off a Date yields none.
+// A Map, a Set and a typed array still pass, so the field is emptied rather than refused.
+func objectField(name string, value goja.Value) (*goja.Object, error) {
+	obj, ok := value.(*goja.Object)
+	if !ok || obj.ClassName() != "Object" {
+		return nil, fmt.Errorf("%s must be an object", name)
 	}
-
-	// Headers
-	if v := obj.Get("headers"); v != nil && !goja.IsUndefined(v) && !goja.IsNull(v) {
-		req.Headers = e.objectToStringSliceMap(v.ToObject(e.runtime))
-	}
-
-	// Params
-	if v := obj.Get("params"); v != nil && !goja.IsUndefined(v) && !goja.IsNull(v) {
-		req.Params = e.objectToStringSliceMap(v.ToObject(e.runtime))
-	}
-
-	// Cookies
-	if v := obj.Get("cookies"); v != nil && !goja.IsUndefined(v) && !goja.IsNull(v) {
-		req.Cookies = e.objectToStringSliceMap(v.ToObject(e.runtime))
-	}
-
-	return nil
+	return obj, nil
 }
 
 // stringSliceToArray converts a Go []string to a JavaScript array.
@@ -245,3 +295,29 @@ func jsStringValue(v goja.Value) (string, bool) {
 	}
 	return v.String(), true
 }
+
+// isGeneratorFunction reports whether a function is declared with a star.
+// The name comes from the script's own prototype chain, so a script can falsify it either way.
+// Reading it can run a script getter, so the whole walk stays inside Try.
+func isGeneratorFunction(runtime *goja.Runtime, value goja.Value) bool {
+	var name string
+	thrown := runtime.Try(func() {
+		obj := value.ToObject(runtime)
+		if obj == nil {
+			return
+		}
+		constructor := obj.Get("constructor")
+		if constructor == nil || goja.IsUndefined(constructor) || goja.IsNull(constructor) {
+			return
+		}
+		constructorObj := constructor.ToObject(runtime)
+		if constructorObj == nil {
+			return
+		}
+		if value := constructorObj.Get("name"); value != nil {
+			name = value.String()
+		}
+	})
+
+	return thrown == nil && name == "GeneratorFunction"
+}

internal/script/js_http.go

@@ -159,6 +159,16 @@ func (e *JsEngine) httpResponseToObject(resp *HTTPResponse) *goja.Object {
 		}
 		return value
 	})
+	// body is a JavaScript string, so bytes that are not valid UTF-8 reach the script
+	// only through this.
+	_ = obj.Set("bytes", func(goja.FunctionCall) goja.Value {
+		buffer := rt.NewArrayBuffer([]byte(resp.Body))
+		value, err := rt.New(rt.Get("Uint8Array").ToObject(rt), rt.ToValue(buffer))
+		if err != nil {
+			panic(err)
+		}
+		return value
+	})
 
 	return obj
 }

internal/script/lua_json.go

@@ -45,9 +45,14 @@ func luaJSONDecode(state *lua.LState) int {
 	return 1
 }
 
+// luaJSONMaxDepth matches the depth encoding/json accepts, so a table a script
+// decoded always encodes again, and it stays far below what overflows the Go stack.
+const luaJSONMaxDepth = 10000
+
 // luaToGo converts a Lua value to a JSON-encodable Go value.
 // It can return the following errors:
 //   - types.ErrScriptJSONCycle
+//   - types.ErrScriptJSONDepth
 //   - types.ScriptTypeError
 func luaToGo(value lua.LValue, visiting map[*lua.LTable]bool) (any, error) {
 	switch v := value.(type) {
@@ -63,6 +68,12 @@ func luaToGo(value lua.LValue, visiting map[*lua.LTable]bool) (any, error) {
 		if visiting[v] {
 			return nil, types.ErrScriptJSONCycle
 		}
+		// visiting holds the tables on the current path, so its size is the depth.
+		// A table millions of levels deep overflows the Go stack, which is a fatal
+		// error no pcall can catch, so the descent is bounded well before that.
+		if len(visiting) >= luaJSONMaxDepth {
+			return nil, types.ErrScriptJSONDepth
+		}
 		visiting[v] = true
 		defer delete(visiting, v)
 

internal/types/errors.go

@@ -17,6 +17,10 @@ var (
 	)
 
 	ErrRemoteFileTooLarge = errors.New("remote file exceeds " + FormatByteSize(RemoteFetchLimit))
+
+	ErrResponseBodyTooLarge = errors.New("response body exceeds the body limit")
+
+	ErrYAMLMultipleDocuments = errors.New("expected a single YAML document, but found more than one")
 )
 
 type FieldParseError struct {
@@ -304,6 +308,27 @@ func (e CLIUnexpectedArgsError) Error() string {
 
 // ======================================== Config File ========================================
 
+// ConfigFileError names the file a parse error came from, which nested configFile chains lose.
+type ConfigFileError struct {
+	Path  string
+	error error
+}
+
+func NewConfigFileError(path string, err error) ConfigFileError {
+	if err == nil {
+		err = errNoError
+	}
+	return ConfigFileError{path, err}
+}
+
+func (e ConfigFileError) Error() string {
+	return e.error.Error()
+}
+
+func (e ConfigFileError) Unwrap() error {
+	return e.error
+}
+
 type ConfigFileReadError struct {
 	error error
 }
@@ -409,14 +434,15 @@ var (
 	ErrScriptSourceEmpty           = errors.New("script source cannot be empty after @")
 	ErrScriptTransformMissing      = errors.New("script must define a global 'transform' function")
 	ErrScriptTransformReturnObject = errors.New("transform function must return an object")
+	ErrScriptTransformAsync        = errors.New("transform function must be synchronous, async and generator functions are not supported")
 	ErrScriptURLNoHost             = errors.New("script URL must have a host")
 	ErrScriptHTTPOutsideTransform  = errors.New("http functions can only be called while transform is running")
 	ErrScriptHTTPUnavailable       = errors.New("http client is not available")
 	ErrScriptHTTPMethodEmpty       = errors.New("http method cannot be empty")
 	ErrScriptHTTPURLInvalid        = errors.New("URL must be an absolute http or https URL")
 	ErrScriptHTTPUnknownOption     = errors.New("unknown option")
-	ErrScriptHTTPBodyTooLarge      = errors.New("response body exceeds the body limit")
 	ErrScriptJSONCycle             = errors.New("cannot encode a table that contains itself")
+	ErrScriptJSONDepth             = errors.New("cannot encode a table nested too deeply")
 )
 
 type ScriptTypeError struct {

nix/package.nix

@@ -8,11 +8,11 @@
 
 (buildGoModule.override { go = go_1_27; }) (finalAttrs: {
   pname = "sarin";
-  version = "1.4.4"; # bump per release
+  version = "1.5.0"; # bump per release
 
   src = lib.cleanSource ../.;
 
-  vendorHash = "sha256-KUxzFDxYbKvKASMze+f7jxfpCQbs01ezeG6a1VboHxw=";
+  vendorHash = "sha256-IlswpF2Qmgi62timxd/xppg3tAyoQFdzkbda4nBFwE0=";
 
   subPackages = [ "cmd/cli" ];