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Adding missing comments in curl source (#1440)

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fixes: #1416
This commit is contained in:
Victor Vazquez 2021-01-26 00:19:09 -08:00 committed by GitHub
parent ae53a38c7a
commit ccccd115f8
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GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 53 additions and 31 deletions
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84
sdk/core/azure-core/src/http/curl/curl.cpp
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@ -463,25 +463,42 @@ void CurlSession::ParseChunkSize(Context const& context)
(void)err;
// Server can return something like `\n\r\n` for a chunk of zero length data. This is
// allowed by RFC. `stoull` will throw invalid_argument if there is not at least one hex
// digit to be parsed. For those cases, we consider the response as zero-lenght.
// digit to be parsed. For those cases, we consider the response as zero-length.
this->m_chunkSize = 0;
}
if (this->m_chunkSize == 0)
{ // Response with no content. end of chunk
keepPolling = false;
/*
* The index represents the current position while reading.
* When the chunkSize is 0, the index should have already read up to the next CRLF.
* When reading again, we want to start reading from the next position, so we need to add
* 1 to the index.
*/
this->m_bodyStartInBuffer = index + 1;
break;
}
if (index + 1 == this->m_innerBufferSize)
{ // on last index. Whatever we read is the BodyStart here
{
/*
* index + 1 represents the next possition to Read. If that's equal to the inner buffer
* size it means that there is no more data and we need to fetch more from network. And
* whatever we fetch will be the start of the chunk data. The bodyStart is set to 0 to
* indicate the the next read call should read from the inner buffer start.
*/
this->m_innerBufferSize = m_connection->ReadFromSocket(
context, this->m_readBuffer, Details::c_DefaultLibcurlReaderSize);
this->m_bodyStartInBuffer = 0;
}
else
{ // not at the end, buffer like [999 \r\nBody...]
{
/*
* index + 1 represents the next position to Read. If that's NOT equal to the inner
* buffer size, it means that there is chunk data in the inner buffer. So, we set the
* start to the next position to read.
*/
this->m_bodyStartInBuffer = index + 1;
}
@ -651,7 +668,9 @@ int64_t CurlSession::OnRead(Context const& context, uint8_t* buffer, int64_t cou
if (this->IsEOF())
{
// Final CRLF after end of chunk
/* For a chunk response, EOF means that the last chunk was found.
* As per RFC, after the last chunk, there should be one last CRLF
*/
ReadCRLF(context);
// after parsing next chunk, check if it is zero
return 0;
@ -704,16 +723,17 @@ int64_t CurlSession::OnRead(Context const& context, uint8_t* buffer, int64_t cou
this->m_sessionTotalRead += totalRead;
// Reading 0 bytes means closed connection.
// For known content length and chunked response, this means there is nothing else to read from
// server or lost connection before getting full response.
// For unknown response size, it means the end of response and it's fine.
// For known content length and chunked response, this means there is nothing else to read
// from server or lost connection before getting full response. For unknown response size,
// it means the end of response and it's fine.
if (totalRead == 0 && (this->m_contentLength > 0 || this->m_isChunkedResponseType))
{
auto expectedToRead = this->m_isChunkedResponseType ? this->m_chunkSize : this->m_contentLength;
if (this->m_sessionTotalRead < expectedToRead)
{
throw TransportException(
"Connection closed before getting full response or response is less than expected. "
"Connection closed before getting full response or response is less than "
"expected. "
"Expected response length = "
+ std::to_string(expectedToRead)
+ ". Read until now = " + std::to_string(this->m_sessionTotalRead));
@ -732,10 +752,10 @@ int64_t CurlConnection::ReadFromSocket(Context const& context, uint8_t* buffer,
// `pollSocketUntilEventOrTimeout` and wait for socket to be ready to read.
// `pollSocketUntilEventOrTimeout` will then handle cancelation token.
// If socket is not ready before the timeout, Exception is thrown.
// When socket is ready, it calls curl_easy_recv() again (second loop iteration). It is not
// expected to return CURLE_AGAIN (since socket is ready), so, a chuck of data will be downloaded
// and result will be CURLE_OK which breaks the loop. Also, getting other than CURLE_OK or
// CURLE_AGAIN throws.
// When socket is ready, it calls curl_easy_recv() again (second loop iteration). It is
// not expected to return CURLE_AGAIN (since socket is ready), so, a chuck of data will be
// downloaded and result will be CURLE_OK which breaks the loop. Also, getting other than
// CURLE_OK or CURLE_AGAIN throws.
size_t readBytes = 0;
for (CURLcode readResult = CURLE_AGAIN; readResult == CURLE_AGAIN;)
{
@ -829,8 +849,8 @@ int64_t CurlSession::ResponseBufferParser::Parse(
}
else
{
// Should never happen that parser is not statusLIne or Headers and we still try to parse
// more.
// Should never happen that parser is not statusLIne or Headers and we still try
// to parse more.
throw;
}
// clean internal buffer
@ -866,8 +886,8 @@ int64_t CurlSession::ResponseBufferParser::Parse(
}
else
{
// Should never happen that parser is not statusLIne or Headers and we still try to parse
// more.
// Should never happen that parser is not statusLIne or Headers and we still try
// to parse more.
throw;
}
}
@ -964,14 +984,15 @@ int64_t CurlSession::ResponseBufferParser::BuildHeader(
if (bufferSize == 1 && buffer[0] == '\n')
{
// rare case of using buffer of size 1 to read. In this case, if the char is next value after
// headers or previous header, just consider it as read and return
// rare case of using buffer of size 1 to read. In this case, if the char is next value
// after headers or previous header, just consider it as read and return
return bufferSize;
}
else if (bufferSize > 1 && this->m_internalBuffer.size() == 0) // only if nothing in buffer,
// advance
else if (bufferSize > 1 && this->m_internalBuffer.size() == 0) // only if nothing in
// buffer, advance
{
// move offset one possition. This is because readStatusLine and readHeader will read up to
// move offset one possition. This is because readStatusLine and readHeader will read up
// to
// '\r' then next delimiter is '\n' and we don't care
start = buffer + 1;
}
@ -984,8 +1005,8 @@ int64_t CurlSession::ResponseBufferParser::BuildHeader(
// \r found at the start means the end of headers
this->m_internalBuffer.clear();
this->m_parseCompleted = true;
return 1; // can't return more than the found delimiter. On read remaining we need to also
// remove first char
return 1; // can't return more than the found delimiter. On read remaining we need to
// also remove first char
}
if (indexOfEndOfStatusLine == endOfBuffer)
@ -1203,8 +1224,8 @@ std::unique_ptr<CurlNetworkConnection> CurlConnectionPool::GetCurlConnection(
return std::make_unique<CurlConnection>(newHandle, std::move(connectionKey));
}
// Move the connection back to the connection pool. Push it to the front so it becomes the first
// connection to be picked next time some one ask for a connection to the pool (LIFO)
// Move the connection back to the connection pool. Push it to the front so it becomes the
// first connection to be picked next time some one ask for a connection to the pool (LIFO)
void CurlConnectionPool::MoveConnectionBackToPool(
std::unique_ptr<CurlNetworkConnection> connection,
HttpStatusCode lastStatusCode)
@ -1270,13 +1291,14 @@ void CurlConnectionPool::CleanUp()
// a connection that is not expired is found or until all connections are removed.
for (auto connection = index->second.end();;)
{
// loop starts at end(), go back to previous possition. We know the list is size() > 0
// so we are safe to go end() - 1 and find the last element in the list
// loop starts at end(), go back to previous possition. We know the list is
// size() > 0 so we are safe to go end() - 1 and find the last element in the
// list
connection--;
if (connection->get()->isExpired())
{
// remove connection from the pool and update the connection to the next one which
// is going to be list.end()
// remove connection from the pool and update the connection to the next one
// which is going to be list.end()
connection = index->second.erase(connection);
CurlConnectionPool::s_connectionCounter -= 1;
@ -1288,8 +1310,8 @@ void CurlConnectionPool::CleanUp()
}
else
{
// Got a non-expired connection, all connections before this one are not expired.
// Break the loop and continue looping the Pool index
// Got a non-expired connection, all connections before this one are not
// expired. Break the loop and continue looping the Pool index
break;
}
}