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Fixes #635 - bug in async server's connection read #637

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Merged
merged 1 commit into from
Apr 19, 2016
Merged

Fixes #635 - bug in async server's connection read #637

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13 changes: 7 additions & 6 deletions boost/network/protocol/http/server/async_connection.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -378,7 +378,7 @@ struct async_connection
boost::throw_exception(std::system_error(*error_encountered));
if (new_start != read_buffer_.begin()) {
input_range input =
boost::make_iterator_range(new_start, read_buffer_.end());
boost::make_iterator_range(new_start, data_end);
buffer_type::iterator start_tmp = new_start;
new_start = read_buffer_.begin();
auto self = this->shared_from_this();
Expand All @@ -389,11 +389,12 @@ struct async_connection
}

auto self = this->shared_from_this();
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You do not need self here anymore, since it is not used in the lambda (can also be removed from the capture section of the lambda).

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Actually, this "self" variable makes sure that the object is alive -- it ensures that there's a shared reference in the callback that depends on the state of the connection. It's a trick that's tied to how asynchronous programming is really hard to debug. 😀

socket().async_read_some(asio::buffer(read_buffer_),
strand.wrap([this, self, callback](
std::error_code ec, size_t bytes_transferred) {
callback(ec, bytes_transferred);
}));
socket().async_read_some(
asio::buffer(read_buffer_),
strand.wrap([this, self, callback](std::error_code ec,
size_t bytes_transferred) {
this->wrap_read_handler(callback, ec, bytes_transferred);
}));
}

/// Returns a reference to the underlying socket.
Expand Down
79 changes: 69 additions & 10 deletions libs/network/example/http/fileserver.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -21,7 +21,6 @@ struct file_server;
typedef http::server<file_server> server;

struct file_cache {

typedef std::map<std::string, std::pair<void *, std::size_t> > region_map;
typedef std::map<std::string, std::vector<server::response_header> > meta_map;

Expand Down Expand Up @@ -66,7 +65,8 @@ struct file_cache {

regions.insert(std::make_pair(real_filename, std::make_pair(region, size)));
static server::response_header common_headers[] = {
{"Connection", "close"}, {"Content-Type", "x-application/octet-stream"},
{"Connection", "close"},
{"Content-Type", "x-application/octet-stream"},
{"Content-Length", "0"}};
std::vector<server::response_header> headers(common_headers,
common_headers + 3);
Expand All @@ -91,8 +91,7 @@ struct file_cache {
static std::vector<server::response_header> empty_vector;
auto headers = file_headers.find(doc_root_ + path);
if (headers != file_headers.end()) {
auto begin = headers->second.begin(),
end = headers->second.end();
auto begin = headers->second.begin(), end = headers->second.end();
return boost::make_iterator_range(begin, end);
} else
return boost::make_iterator_range(empty_vector);
Expand Down Expand Up @@ -138,22 +137,75 @@ struct connection_handler : std::enable_shared_from_this<connection_handler> {
asio::const_buffers_1(
static_cast<char const *>(mmaped_region.first) + offset,
rightmost_bound - offset),
[=] (std::error_code const &ec) {
[=](std::error_code const &ec) {
self->handle_chunk(mmaped_region, rightmost_bound, connection, ec);
});
}

void handle_chunk(std::pair<void *, std::size_t> mmaped_region, off_t offset,
server::connection_ptr connection,
std::error_code const &ec) {
assert(offset>=0);
assert(offset >= 0);
if (!ec && static_cast<std::size_t>(offset) < mmaped_region.second)
send_file(mmaped_region, offset, connection);
}

file_cache &file_cache_;
};

struct input_consumer : public std::enable_shared_from_this<input_consumer> {
// Maximum size for incoming request bodies.
static constexpr std::size_t MAX_INPUT_BODY_SIZE = 2 << 16;

explicit input_consumer(std::shared_ptr<connection_handler> h,
server::request r)
: request_(std::move(r)), handler_(std::move(h)), content_length_{0} {
for (const auto &header : request_.headers) {
if (boost::iequals(header.name, "content-length")) {
content_length_ = std::stoul(header.value);
std::cerr << "Content length: " << content_length_ << '\n';
break;
}
}
}

void operator()(server::connection::input_range input, std::error_code ec,
std::size_t bytes_transferred,
server::connection_ptr connection) {
std::cerr << "Callback: " << bytes_transferred << "; ec = " << ec << '\n';
if (ec == asio::error::eof) return;
if (!ec) {
if (empty(input))
return (*handler_)(request_.destination, connection, true);
request_.body.insert(request_.body.end(), boost::begin(input),
boost::end(input));
if (request_.body.size() > MAX_INPUT_BODY_SIZE) {
connection->set_status(server::connection::bad_request);
static server::response_header error_headers[] = {
{"Connection", "close"}};
connection->set_headers(
boost::make_iterator_range(error_headers, error_headers + 1));
connection->write("Body too large.");
return;
}
std::cerr << "Body: " << request_.body << '\n';
if (request_.body.size() == content_length_)
return (*handler_)(request_.destination, connection, true);
std::cerr << "Scheduling another read...\n";
auto self = this->shared_from_this();
connection->read([self](server::connection::input_range input,
std::error_code ec, std::size_t bytes_transferred,
server::connection_ptr connection) {
(*self)(input, ec, bytes_transferred, connection);
});
}
}

server::request request_;
std::shared_ptr<connection_handler> handler_;
size_t content_length_;
};

struct file_server {
explicit file_server(file_cache &cache) : cache_(cache) {}

Expand All @@ -165,6 +217,14 @@ struct file_server {
} else if (request.method == "GET") {
std::shared_ptr<connection_handler> h(new connection_handler(cache_));
(*h)(request.destination, connection, true);
} else if (request.method == "PUT" || request.method == "POST") {
auto h = std::make_shared<connection_handler>(cache_);
auto c = std::make_shared<input_consumer>(h, request);
connection->read([c](server::connection::input_range input,
std::error_code ec, std::size_t bytes_transferred,
server::connection_ptr connection) {
(*c)(input, ec, bytes_transferred, connection);
});
} else {
static server::response_header error_headers[] = {
{"Connection", "close"}};
Expand All @@ -184,11 +244,10 @@ int main(int, char *[]) {
file_server handler(cache);
server::options options(handler);
server instance(options.thread_pool(std::make_shared<utils::thread_pool>(4))
.address("0.0.0.0")
.port("8000"));
.address("0.0.0.0")
.port("8000"));
instance.run();
}
catch (std::exception &e) {
} catch (std::exception &e) {
std::cerr << e.what() << std::endl;
}
}