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// Copyright 2016 `multipart` Crate Developers
//
// Licensed under the Apache License, Version 2.0, <LICENSE-APACHE or
// http://apache.org/licenses/LICENSE-2.0> or the MIT license <LICENSE-MIT or
// http://opensource.org/licenses/MIT>, at your option. This file may not be
// copied, modified, or distributed except according to those terms.
//! `multipart` field header parsing.
use mime::{Mime, TopLevel, SubLevel};
use quick_error::ResultExt;
use std::error::Error;
use std::io::{self, Read, BufRead};
use std::{str, fmt};
// The AsciiExt import is needed for Rust older than 1.23.0. These two lines can
// be removed when supporting older Rust is no longer needed.
#[allow(deprecated, unused_imports)]
use std::ascii::AsciiExt;
use super::httparse::{self, EMPTY_HEADER, Header, Status, Error as HttparseError};
use self::ReadEntryResult::*;
use super::save::SaveBuilder;
use super::ArcStr;
const EMPTY_STR_HEADER: StrHeader<'static> = StrHeader {
name: "",
val: "",
};
macro_rules! invalid_cont_disp {
($reason: expr, $cause: expr) => {
return Err(
ParseHeaderError::InvalidContDisp($reason, $cause.to_string())
);
}
}
/// Not exposed
#[derive(Copy, Clone, Debug)]
pub struct StrHeader<'a> {
name: &'a str,
val: &'a str,
}
struct DisplayHeaders<'s, 'a: 's>(&'s [StrHeader<'a>]);
impl <'s, 'a: 's> fmt::Display for DisplayHeaders<'s, 'a> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
for hdr in self.0 {
writeln!(f, "{}: {}", hdr.name, hdr.val)?;
}
Ok(())
}
}
fn with_headers<R, F, Ret>(r: &mut R, closure: F) -> Result<Ret, ParseHeaderError>
where R: BufRead, F: FnOnce(&[StrHeader]) -> Ret {
const HEADER_LEN: usize = 4;
let consume;
let ret;
let mut last_len = 0;
loop {
// this should return a larger buffer each time
let buf = r.fill_buf()?;
// buffer has stopped growing
if buf.len() == last_len {
return Err(ParseHeaderError::TooLarge);
}
let mut raw_headers = [EMPTY_HEADER; HEADER_LEN];
match httparse::parse_headers(buf, &mut raw_headers)? {
// read more and try again
Status::Partial => last_len = buf.len(),
Status::Complete((consume_, raw_headers)) => {
let mut headers = [EMPTY_STR_HEADER; HEADER_LEN];
let headers = copy_headers(raw_headers, &mut headers)?;
debug!("Parsed headers: {:?}", headers);
consume = consume_;
ret = closure(headers);
break;
},
}
}
r.consume(consume);
Ok(ret)
}
fn copy_headers<'h, 'b: 'h>(raw: &[Header<'b>], headers: &'h mut [StrHeader<'b>]) -> io::Result<&'h [StrHeader<'b>]> {
for (raw, header) in raw.iter().zip(&mut *headers) {
header.name = raw.name;
header.val = io_str_utf8(raw.value)?;
}
Ok(&headers[..raw.len()])
}
/// The headers that (may) appear before a `multipart/form-data` field.
///
/// ### Warning: Values are Client-Provided
/// Everything in this struct are values from the client and should be considered **untrustworthy**.
/// This crate makes no effort to validate or sanitize any client inputs.
#[derive(Clone, Debug)]
pub struct FieldHeaders {
/// The field's name from the form.
pub name: ArcStr,
/// The filename of this entry, if supplied. This is not guaranteed to match the original file
/// or even to be a valid filename for the current platform.
pub filename: Option<String>,
/// The MIME type (`Content-Type` value) of this file, if supplied by the client.
///
/// If this is not supplied, the content-type of the field should default to `text/plain` as
/// per [IETF RFC 7578, section 4.4](https://tools.ietf.org/html/rfc7578#section-4.4), but this
/// should not be implicitly trusted. This crate makes no attempt to identify or validate
/// the content-type of the actual field data.
pub content_type: Option<Mime>,
}
impl FieldHeaders {
/// Parse the field headers from the passed `BufRead`, consuming the relevant bytes.
fn read_from<R: BufRead>(r: &mut R) -> Result<Self, ParseHeaderError> {
with_headers(r, Self::parse)?
}
fn parse(headers: &[StrHeader]) -> Result<FieldHeaders, ParseHeaderError> {
let cont_disp = ContentDisp::parse_required(headers)?;
Ok(FieldHeaders {
name: cont_disp.field_name.into(),
filename: cont_disp.filename,
content_type: parse_content_type(headers)?,
})
}
}
/// The `Content-Disposition` header.
struct ContentDisp {
/// The name of the `multipart/form-data` field.
field_name: String,
/// The optional filename for this field.
filename: Option<String>,
}
impl ContentDisp {
fn parse_required(headers: &[StrHeader]) -> Result<ContentDisp, ParseHeaderError> {
let header = if let Some(header) = find_header(headers, "Content-Disposition") {
header
} else {
return Err(ParseHeaderError::MissingContentDisposition(
DisplayHeaders(headers).to_string()
));
};
// Content-Disposition: ?
let after_disp_type = match split_once(header.val, ';') {
Some((disp_type, after_disp_type)) => {
// assert Content-Disposition: form-data
// but needs to be parsed out to trim the spaces (allowed by spec IIRC)
if disp_type.trim() != "form-data" {
invalid_cont_disp!("unexpected Content-Disposition value", disp_type);
}
after_disp_type
},
None => invalid_cont_disp!("expected additional data after Content-Disposition type",
header.val),
};
// Content-Disposition: form-data; name=?
let (field_name, filename) = match get_str_after("name=", ';', after_disp_type) {
None => invalid_cont_disp!("expected field name and maybe filename, got",
after_disp_type),
// Content-Disposition: form-data; name={field_name}; filename=?
Some((field_name, after_field_name)) => {
let field_name = trim_quotes(field_name);
let filename = get_str_after("filename=", ';', after_field_name)
.map(|(filename, _)| trim_quotes(filename).to_owned());
(field_name, filename)
},
};
Ok(ContentDisp { field_name: field_name.to_owned(), filename })
}
}
fn parse_content_type(headers: &[StrHeader]) -> Result<Option<Mime>, ParseHeaderError> {
if let Some(header) = find_header(headers, "Content-Type") {
// Boundary parameter will be parsed into the `Mime`
debug!("Found Content-Type: {:?}", header.val);
Ok(Some(header.val.parse::<Mime>()
.map_err(|_| ParseHeaderError::MimeError(header.val.into()))?))
} else {
Ok(None)
}
}
/// A field in a multipart request with its associated headers and data.
#[derive(Debug)]
pub struct MultipartField<M: ReadEntry> {
/// The headers for this field, including the name, filename, and content-type, if provided.
///
/// ### Warning: Values are Client-Provided
/// Everything in this struct are values from the client and should be considered **untrustworthy**.
/// This crate makes no effort to validate or sanitize any client inputs.
pub headers: FieldHeaders,
/// The field's data.
pub data: MultipartData<M>,
}
impl<M: ReadEntry> MultipartField<M> {
/// Returns `true` if this field has no content-type or the content-type is `text/...`.
///
/// This typically means it can be read to a string, but it could still be using an unsupported
/// character encoding, so decoding to `String` needs to ensure that the data is valid UTF-8.
///
/// Note also that the field contents may be too large to reasonably fit in memory.
/// The `.save()` adapter can be used to enforce a size limit.
///
/// Detecting character encodings by any means is (currently) beyond the scope of this crate.
pub fn is_text(&self) -> bool {
self.headers.content_type.as_ref().map_or(true, |ct| ct.0 == TopLevel::Text)
}
/// Read the next entry in the request.
pub fn next_entry(self) -> ReadEntryResult<M> {
self.data.into_inner().read_entry()
}
/// Update `self` as the next entry.
///
/// Returns `Ok(Some(self))` if another entry was read, `Ok(None)` if the end of the body was
/// reached, and `Err(e)` for any errors that occur.
pub fn next_entry_inplace(&mut self) -> io::Result<Option<&mut Self>> where for<'a> &'a mut M: ReadEntry {
let multipart = self.data.take_inner();
match multipart.read_entry() {
Entry(entry) => {
*self = entry;
Ok(Some(self))
},
End(multipart) => {
self.data.give_inner(multipart);
Ok(None)
},
Error(multipart, err) => {
self.data.give_inner(multipart);
Err(err)
}
}
}
}
/// The data of a field in a `multipart/form-data` request.
///
/// You can read it to EOF, or use the `save()` adaptor to save it to disk/memory.
#[derive(Debug)]
pub struct MultipartData<M> {
inner: Option<M>,
}
const DATA_INNER_ERR: &str = "MultipartFile::inner taken and not replaced; this is likely \
caused by a logic error in `multipart` or by resuming after \
a previously caught panic.\nPlease open an issue with the \
relevant backtrace and debug logs at \
https://github.com/abonander/multipart";
impl<M> MultipartData<M> where M: ReadEntry {
/// Get a builder type which can save the field with or without a size limit.
pub fn save(&mut self) -> SaveBuilder<&mut Self> {
SaveBuilder::new(self)
}
/// Take the inner `Multipart` or `&mut Multipart`
pub fn into_inner(self) -> M {
self.inner.expect(DATA_INNER_ERR)
}
/// Set the minimum buffer size that `BufRead::fill_buf(self)` will return
/// until the end of the stream is reached. Set this as small as you can tolerate
/// to minimize `read()` calls (`read()` won't be called again until the buffer
/// is smaller than this).
///
/// This value is reset between fields.
pub fn set_min_buf_size(&mut self, min_buf_size: usize) {
self.inner_mut().set_min_buf_size(min_buf_size)
}
fn inner_mut(&mut self) -> &mut M {
self.inner.as_mut().expect(DATA_INNER_ERR)
}
fn take_inner(&mut self) -> M {
self.inner.take().expect(DATA_INNER_ERR)
}
fn give_inner(&mut self, inner: M) {
self.inner = Some(inner);
}
}
impl<M: ReadEntry> Read for MultipartData<M> {
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize>{
self.inner_mut().source_mut().read(buf)
}
}
/// In this implementation, `fill_buf()` can return more data with each call.
///
/// Use `set_min_buf_size()` if you require a minimum buffer length.
impl<M: ReadEntry> BufRead for MultipartData<M> {
fn fill_buf(&mut self) -> io::Result<&[u8]> {
self.inner_mut().source_mut().fill_buf()
}
fn consume(&mut self, amt: usize) {
self.inner_mut().source_mut().consume(amt)
}
}
fn split_once(s: &str, delim: char) -> Option<(&str, &str)> {
s.find(delim).map(|idx| s.split_at(idx))
}
fn trim_quotes(s: &str) -> &str {
s.trim_matches('"')
}
/// Get the string after `needle` in `haystack`, stopping before `end_val_delim`
fn get_str_after<'a>(needle: &str, end_val_delim: char, haystack: &'a str) -> Option<(&'a str, &'a str)> {
let val_start_idx = try_opt!(haystack.find(needle)) + needle.len();
let val_end_idx = haystack[val_start_idx..].find(end_val_delim)
.map_or(haystack.len(), |end_idx| end_idx + val_start_idx);
Some((&haystack[val_start_idx..val_end_idx], &haystack[val_end_idx..]))
}
fn io_str_utf8(buf: &[u8]) -> io::Result<&str> {
str::from_utf8(buf).map_err(|e| io::Error::new(io::ErrorKind::InvalidData, e))
}
fn find_header<'a, 'b>(headers: &'a [StrHeader<'b>], name: &str) -> Option<&'a StrHeader<'b>> {
// Field names are case insensitive and consist of ASCII characters
// only (see https://tools.ietf.org/html/rfc822#section-3.2).
headers.iter().find(|header| header.name.eq_ignore_ascii_case(name))
}
/// Common trait for `Multipart` and `&mut Multipart`
pub trait ReadEntry: PrivReadEntry + Sized {
/// Attempt to read the next entry in the multipart stream.
fn read_entry(mut self) -> ReadEntryResult<Self> {
self.set_min_buf_size(super::boundary::MIN_BUF_SIZE);
debug!("ReadEntry::read_entry()");
if !try_read_entry!(self; self.consume_boundary()) {
return End(self);
}
let field_headers: FieldHeaders = try_read_entry!(self; self.read_headers());
if let Some(ct) = field_headers.content_type.as_ref() {
if ct.0 == TopLevel::Multipart {
// fields of this type are sent by (supposedly) no known clients
// (https://tools.ietf.org/html/rfc7578#appendix-A) so I'd be fascinated
// to hear about any in the wild
info!("Found nested multipart field: {:?}:\r\n\
Please report this client's User-Agent and any other available details \
at https://github.com/abonander/multipart/issues/56",
field_headers);
}
}
Entry(
MultipartField {
headers: field_headers,
data: MultipartData {
inner: Some(self),
},
}
)
}
/// Equivalent to `read_entry()` but takes `&mut self`
fn read_entry_mut(&mut self) -> ReadEntryResult<&mut Self> {
ReadEntry::read_entry(self)
}
}
impl<T> ReadEntry for T where T: PrivReadEntry {}
/// Public trait but not re-exported.
pub trait PrivReadEntry {
type Source: BufRead;
fn source_mut(&mut self) -> &mut Self::Source;
fn set_min_buf_size(&mut self, min_buf_size: usize);
/// Consume the next boundary.
/// Returns `true` if a field should follow, `false` otherwise.
fn consume_boundary(&mut self) -> io::Result<bool>;
fn read_headers(&mut self) -> Result<FieldHeaders, io::Error> {
FieldHeaders::read_from(self.source_mut())
.map_err(|e| io::Error::new(io::ErrorKind::InvalidData, e))
}
fn read_to_string(&mut self) -> io::Result<String> {
let mut buf = String::new();
match self.source_mut().read_to_string(&mut buf) {
Ok(_) => Ok(buf),
Err(err) => Err(err),
}
}
}
impl<'a, M: ReadEntry> PrivReadEntry for &'a mut M {
type Source = M::Source;
fn source_mut(&mut self) -> &mut M::Source {
(**self).source_mut()
}
fn set_min_buf_size(&mut self, min_buf_size: usize) {
(**self).set_min_buf_size(min_buf_size)
}
fn consume_boundary(&mut self) -> io::Result<bool> {
(**self).consume_boundary()
}
}
/// Ternary result type returned by `ReadEntry::next_entry()`,
/// `Multipart::into_entry()` and `MultipartField::next_entry()`.
pub enum ReadEntryResult<M: ReadEntry, Entry = MultipartField<M>> {
/// The next entry was found.
Entry(Entry),
/// No more entries could be read.
End(M),
/// An error occurred.
Error(M, io::Error),
}
impl<M: ReadEntry, Entry> ReadEntryResult<M, Entry> {
/// Convert `self` into `Result<Option<Entry>>` as follows:
///
/// * `Entry(entry) -> Ok(Some(entry))`
/// * `End(_) -> Ok(None)`
/// * `Error(_, err) -> Err(err)`
pub fn into_result(self) -> io::Result<Option<Entry>> {
match self {
ReadEntryResult::Entry(entry) => Ok(Some(entry)),
ReadEntryResult::End(_) => Ok(None),
ReadEntryResult::Error(_, err) => Err(err),
}
}
/// Attempt to unwrap `Entry`, panicking if this is `End` or `Error`.
pub fn unwrap(self) -> Entry {
self.expect_alt("`ReadEntryResult::unwrap()` called on `End` value",
"`ReadEntryResult::unwrap()` called on `Error` value: {:?}")
}
/// Attempt to unwrap `Entry`, panicking if this is `End` or `Error`
/// with the given message. Adds the error's message in the `Error` case.
pub fn expect(self, msg: &str) -> Entry {
self.expect_alt(msg, msg)
}
/// Attempt to unwrap `Entry`, panicking if this is `End` or `Error`.
/// If this is `End`, panics with `end_msg`; if `Error`, panics with `err_msg`
/// as well as the error's message.
pub fn expect_alt(self, end_msg: &str, err_msg: &str) -> Entry {
match self {
Entry(entry) => entry,
End(_) => panic!("{}", end_msg),
Error(_, err) => panic!("{}: {:?}", err_msg, err),
}
}
/// Attempt to unwrap as `Option<Entry>`, panicking in the `Error` case.
pub fn unwrap_opt(self) -> Option<Entry> {
self.expect_opt("`ReadEntryResult::unwrap_opt()` called on `Error` value")
}
/// Attempt to unwrap as `Option<Entry>`, panicking in the `Error` case
/// with the given message as well as the error's message.
pub fn expect_opt(self, msg: &str) -> Option<Entry> {
match self {
Entry(entry) => Some(entry),
End(_) => None,
Error(_, err) => panic!("{}: {:?}", msg, err),
}
}
}
const GENERIC_PARSE_ERR: &str = "an error occurred while parsing field headers";
quick_error! {
#[derive(Debug)]
enum ParseHeaderError {
/// The `Content-Disposition` header was not found
MissingContentDisposition(headers: String) {
display(x) -> ("{}:\n{}", x.description(), headers)
description("\"Content-Disposition\" header not found in field headers")
}
InvalidContDisp(reason: &'static str, cause: String) {
display(x) -> ("{}: {}: {}", x.description(), reason, cause)
description("invalid \"Content-Disposition\" header")
}
/// The header was found but could not be parsed
TokenizeError(err: HttparseError) {
description(GENERIC_PARSE_ERR)
display(x) -> ("{}: {}", x.description(), err)
cause(err)
from()
}
MimeError(cont_type: String) {
description("Failed to parse Content-Type")
display(this) -> ("{}: {}", this.description(), cont_type)
}
TooLarge {
description("field headers section ridiculously long or missing trailing CRLF-CRLF")
}
/// IO error
Io(err: io::Error) {
description("an io error occurred while parsing the headers")
display(x) -> ("{}: {}", x.description(), err)
cause(err)
from()
}
}
}
#[test]
fn test_find_header() {
let headers = [
StrHeader { name: "Content-Type", val: "text/plain" },
StrHeader { name: "Content-disposition", val: "form-data" },
StrHeader { name: "content-transfer-encoding", val: "binary" }
];
assert_eq!(find_header(&headers, "Content-Type").unwrap().val, "text/plain");
assert_eq!(find_header(&headers, "Content-Disposition").unwrap().val, "form-data");
assert_eq!(find_header(&headers, "Content-Transfer-Encoding").unwrap().val, "binary");
}