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[Junie]: fix: handle multipart boundary parsing in KTOR 3.0 #4872

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[Junie]: fix: handle multipart boundary parsing in KTOR 3.0 #4872

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11 changes: 10 additions & 1 deletion ktor-http/ktor-http-cio/common/src/io/ktor/http/cio/HttpParser.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -306,7 +306,16 @@ internal fun parseHeaderValue(text: CharArrayBuilder, range: MutableRange) {
}

private fun noColonFound(text: CharSequence, range: MutableRange): Nothing {
throw ParserException("No colon in HTTP header in ${text.substring(range.start, range.end)} in builder: \n$text")
val headerText = text.substring(range.start, range.end)

// Check if this might be a multipart boundary line (starts with -- and might end with --)
if (headerText.startsWith("--") && (headerText.endsWith("--") || headerText.isEmpty())) {
Comment on lines +311 to +312
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Copilot AI May 21, 2025

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Extracting the multipart boundary detection logic into a helper method could improve clarity and reduce the risk of subtle bugs from relying on string pattern comparisons directly.

Suggested change
// Check if this might be a multipart boundary line (starts with -- and might end with --)
if (headerText.startsWith("--") && (headerText.endsWith("--") || headerText.isEmpty())) {
if (isMultipartBoundary(headerText)) {

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// This is likely a multipart boundary line, not a header
// We'll throw a specific exception that can be caught and handled by the multipart parser
throw ParserException("Multipart boundary detected: $headerText")
}

throw ParserException("No colon in HTTP header in $headerText in builder: \n$text")
}

private fun characterIsNotAllowed(text: CharSequence, ch: Char): Nothing =
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14 changes: 12 additions & 2 deletions ktor-http/ktor-http-cio/common/src/io/ktor/http/cio/Multipart.kt
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Expand Up @@ -111,8 +111,18 @@ private suspend fun parsePartHeadersImpl(input: ByteReadChannel): HttpHeadersMap
val builder = CharArrayBuilder()

try {
return parseHeaders(input, builder)
?: throw EOFException("Failed to parse multipart headers: unexpected end of stream")
try {
return parseHeaders(input, builder)
?: throw EOFException("Failed to parse multipart headers: unexpected end of stream")
} catch (e: ParserException) {
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Copilot AI May 21, 2025

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Using exception message prefixes for control flow may be fragile; consider using a dedicated exception type or a flag to clearly indicate a multipart boundary condition.

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// Check if this is our special case for multipart boundary
if (e.message?.startsWith("Multipart boundary detected:") == true) {
// This is a boundary line, not a header
// Return empty headers to signal that this is not a valid part
return HttpHeadersMap(builder)
}
throw e
}
} catch (t: Throwable) {
builder.release()
throw t
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