Enum Error 

#[non_exhaustive]
pub enum Error {
    InvalidProxyServer {
        input: String,
        reason: String,
    },
    InvalidBypassPattern {
        input: String,
        reason: String,
    },
    InvalidProxyUrl {
        input: String,
        source: ParseError,
    },
    UnsupportedProxyScheme(String),
    CgiHttpProxy {
        variable: String,
    },
    Io {
        context: String,
        source: Error,
    },
    Sandboxed {
        sandbox: String,
        reason: String,
    },
    Unsupported,
    PacNotSupported {
        mode: &'static str,
    },
    ProxyEntryUnusable {
        scheme: Scheme,
        rejected: RejectedValue,
    },
    PacFetchRequired {
        url: Url,
    },
    PacEvaluation {
        reason: String,
    },
    PacTimeout {
        timeout: Duration,
    },
    PacInvalidResult {
        result: String,
    },
    PacEngineUnavailable,
}

Errors from reading OS proxy configuration, and from routing a URL through what was read.

#[non_exhaustive]. No #[from] io::Error — I/O is always wrapped with context. Hand-written Debug: PacFetchRequired’s url::Url would print credentials; other payloads are masked at construction or safe.

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

InvalidProxyServer

A Windows ProxyServer style specification could not be parsed.

Fields

input: String

Offending token, masked — and withheld outright when it may be a credential.

reason: String

Why parsing failed.

InvalidBypassPattern

A single bypass / no_proxy / ProxyOverride entry could not be parsed.

Fields

input: String

Offending entry, masked like InvalidProxyServer’s.

reason: String

Why parsing failed.

InvalidProxyUrl

An AutoConfigURL-style setting read from the OS is malformed.

Not the environment: *_proxy values go through ProxyEndpoint::parse, which answers with InvalidProxyServer instead.

Fields

input: String

Offending input, masked like InvalidProxyServer’s.

source: ParseError

Underlying parse error.

UnsupportedProxyScheme(String)

The proxy URL carried a scheme this crate does not understand.

Recognised schemes are listed on ProxyScheme.

CgiHttpProxy

http_proxy under CGI: a non-empty REQUEST_METHOD ⇒ forged Proxy: header (httpoxy, CVE-2016-5385). Refused like Go’s httpproxy; not applied to https_proxy/no_proxy, whose names no request header can produce.

KDE’s ProxyType = 4 raises the same error on a wider rule, because there the file names the variable each slot reads: any name a request header could have set — RFC 3875 §4.1.18’s HTTP_ prefix — is refused whichever slot named it, including the one holding the bypass list. variable is that name as written.

Fields

variable: String

Variable name as set in the environment.

Io

An I/O failure, annotated with the operation that caused it.

OS error codes are carried as std::io::Error, built by from_raw_os_error.

Fields

context: String

Operation in progress when the failure occurred.

source: Error

Underlying I/O error.

Sandboxed

Linux sandbox: desktop settings unreadable (Flatpak without dconf → keyfile defaults). Portal fallback when possible; else this error — not a false Direct.

Fields

sandbox: String

Detected sandbox name.

reason: String

Why no source could be read.

Unsupported

No store to read. Off Windows/macOS/Linux there is no backend at all; on Linux it is a reading and not a property of the build — neither desktop store answered, which both desktop features being off guarantees and which a build with one of them on also reaches whenever the schema and kioslaverc are both missing from the machine.

Not the answer inside a sandbox: that route is chosen before either store is consulted and reports Sandboxed, including when the feature that would carry the portal fallback is off.

PacNotSupported

resolve() needs PAC/WPAD evaluation (resolve_with_pac / pac feature). Deliberately an error, not silent Direct.

resolve_with_pac answers with it too, for WpadAutoDetect handed no script body: discovery is a non-goal, so the fix there is to supply the script rather than to change entry point. mode is "wpad" either way and does not tell the two apart.

Fields

mode: &'static str

Auto-config mode in effect.

ProxyEntryUnusable

The system configured a proxy for this scheme, the value could not be used, and no other entry covers it.

Returning ProxyStep::Direct here would assert something the platform does not do: KDE expands a [$e] value from the session environment and proxies the request, and this crate deliberately does not expand it. Only a scheme with no catch-all reaches this — a live socksProxy covers the drop first, exactly as Chromium’s fallback_proxies does. Where this reports, Chromium goes direct instead: its ProxyList::AddProxyChain drops a malformed entry with “Silently discard malformed inputs”, leaving MapUrlSchemeToProxyList to answer nullptr.

Fields

scheme: Scheme

Which requests lost an answer — read off the drop’s own attribution, not off the slot it was found under. In every mode this crate builds the two are the same value, because each backend files its record against the slot it dropped, so this is the slot, and the slot is what decides coverage rather than the request’s own scheme: a lost catch-all reports Scheme::All whatever was asked for, and a ws/wss request reports whichever of the chain it lost. A caller who hands ProxyMode::manual a record attributed to one scheme under the key of another gets the attribution back rather than the key. Nothing normalises the pair: the record is the caller’s, and the same value is what ProxyMode::rejected hands back.

rejected: RejectedValue

First drop naming that scheme; masked at construction. The rest stay reachable through ProxyMode::rejected on the mode this error was resolved against, which is the caller’s own config.effective wherever the caller supplied it. Where a resolver builds a mode of its own it is not: WinHttpPacResolver::resolve_config answers a WPAD miss by re-reading the registry into a Manual and resolving against that, and the mode goes out of scope with the call while the caller still holds WpadAutoDetect, which has no list. This field is what survives that.

PacFetchRequired

resolve_with_pac + ProxyMode::Pac without script body. Fetch is caller’s job; url stored verbatim, masked only in {}/{:?}.

Fields

url: Url

Script URL.

PacEvaluation

PAC run failed (syntax, throw, limits). reason masked/sanitized at construction.

Fields

reason: String

Engine message (sanitized).

PacTimeout

Evaluating a PAC script overran PacPolicy::timeout.

Fields

timeout: Duration

Budget that was exceeded.

PacInvalidResult

FindProxyForURL returned nothing usable (malformed candidates skipped first). result masked at construction.

Fields

result: String

Raw return string (masked).

PacEngineUnavailable

pac on but no engine (pac-boa or a custom pac::PacEvaluator).

Not linked: the item exists only with the pac feature on, and this variant does not.

Trait Implementations

impl Debug for Error

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for Error

fn fmt(&self, __formatter: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Error for Error

fn source(&self) -> Option<&(dyn Error + 'static)>

Returns the lower-level source of this error, if any.

fn description(&self) -> &str

👎Deprecated since 1.42.0:

use the Display impl or to_string()

fn cause(&self) -> Option<&dyn Error>

👎Deprecated since 1.33.0:

replaced by Error::source, which can support downcasting

fn provide<'a>(&'a self, request: &mut Request<'a>)

🔬This is a nightly-only experimental API. (error_generic_member_access)

Provides type-based access to context intended for error reports.