foundationdb/fdbrpc/HTTP.actor.cpp

/*
 * HTTP.actor.cpp
 *
 * This source file is part of the FoundationDB open source project
 *
 * Copyright 2013-2018 Apple Inc. and the FoundationDB project authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "HTTP.h"
#include "md5/md5.h"
#include "libb64/encode.h"
#include <cctype>
#include "xml2json.hpp"

namespace HTTP {

	std::string urlEncode(const std::string &s) {
		std::string o;
		o.reserve(s.size() * 3);
		char buf[4];
		for(auto c : s)
			if(std::isalnum(c))
				o.append(&c, 1);
			else {
				sprintf(buf, "%%%.02X", c);
				o.append(buf);
			}
		return o;
	}

	bool Response::verifyMD5(bool fail_if_header_missing, Optional<std::string> content_sum) {
		auto i = headers.find("Content-MD5");
		if(i != headers.end()) {
			// If a content sum is not provided, calculate one from the response content
			if(!content_sum.present()) {
				MD5_CTX sum;
				::MD5_Init(&sum);
				::MD5_Update(&sum, content.data(), content.size());
				std::string sumBytes;
				sumBytes.resize(16);
				::MD5_Final((unsigned char *)sumBytes.data(), &sum);
				std::string sumStr = base64::encoder::from_string(sumBytes);
				sumStr.resize(sumStr.size() - 1);
				content_sum = sumStr;
			}
			return i->second == content_sum.get();
		}
		return !fail_if_header_missing;
	}

	void Response::convertToJSONifXML() {
		auto i = headers.find("Content-Type");
		if (i != headers.end() && i->second == "application/xml") {
			content = xml2json(content.c_str());
			contentLen = content.length();
			headers["Content-Type"] = "application/json";
		}
	}

	std::string Response::toString() {
		std::string r = format("Response Code: %d\n", code);
		r += format("Response ContentLen: %lld\n", contentLen);
		for(auto h : headers)
			r += format("Reponse Header: %s: %s\n", h.first.c_str(), h.second.c_str());
		r.append("-- RESPONSE CONTENT--\n");
		r.append(content);
		r.append("\n--------\n");
		return r;
	}

	PacketBuffer * writeRequestHeader(std::string const &verb, std::string const &resource, HTTP::Headers const &headers, PacketBuffer *dest) {
		PacketWriter writer(dest, NULL, Unversioned());
		writer.serializeBytes(verb);
		writer.serializeBytes(" ", 1);
		writer.serializeBytes(resource);
		writer.serializeBytes(LiteralStringRef(" HTTP/1.1\r\n"));
		for(auto h : headers) {
			writer.serializeBytes(h.first);
			writer.serializeBytes(LiteralStringRef(": "));
			writer.serializeBytes(h.second);
			writer.serializeBytes(LiteralStringRef("\r\n"));
		}
		writer.serializeBytes(LiteralStringRef("\r\n"));
		return writer.finish();
	}

	// Read at least 1 bytes from conn and up to maxlen in a single read, append read data into *buf
	// Returns the number of bytes read.
	ACTOR Future<int> read_into_string(Reference<IConnection> conn, std::string *buf, int maxlen) {
		loop {
			// Wait for connection to have something to read
			Void _ = wait(conn->onReadable());
			Void _ = wait( delay( 0, TaskReadSocket ) );

			// Read into buffer
			int originalSize = buf->size();
			// TODO:  resize is zero-initializing the space we're about to overwrite, so do something else, which probably means
			// not using a string for this buffer
			buf->resize(originalSize + maxlen);
			uint8_t *wptr = (uint8_t *)buf->data() + originalSize;
			int len = conn->read(wptr, wptr + maxlen);
			buf->resize(originalSize + len);

			// Make sure data was actually read, it's possible for there to be none.
			if(len > 0)
				return len;
		}
	}

	// Returns the position of delim within buf, relative to pos.  If delim is not found, continues to read from conn until
	// either it is found or the connection ends, at which point connection_failed is thrown and buf contains
	// everything that was read up to that point.
	ACTOR Future<size_t> read_delimited_into_string(Reference<IConnection> conn, const char *delim, std::string *buf, size_t pos) {
		state size_t sPos = pos;
		state int lookBack = strlen(delim) - 1;
		ASSERT(lookBack >= 0);

		loop {
			size_t endPos = buf->find(delim, sPos);
			if(endPos != std::string::npos)
				return endPos - pos;
			// Next search will start at the current end of the buffer - delim size + 1
			if(sPos >= lookBack)
				sPos -= lookBack;
			int _ = wait(read_into_string(conn, buf, CLIENT_KNOBS->HTTP_READ_SIZE));
		}
	}

	// Reads from conn (as needed) until there are at least len bytes starting at pos in buf
	ACTOR Future<Void> read_fixed_into_string(Reference<IConnection> conn, int len, std::string *buf, size_t pos) {
		state int stop_size = pos + len;
		while(buf->size() < stop_size)
			int _ = wait(read_into_string(conn, buf, CLIENT_KNOBS->HTTP_READ_SIZE));
		return Void();
	}

	ACTOR Future<Void> read_http_response_headers(Reference<IConnection> conn, Headers *headers, std::string *buf, size_t *pos) {
		loop {
			// Get a line, reading more data from conn if necessary
			size_t lineLen = wait(read_delimited_into_string(conn, "\r\n", buf, *pos));

			// If line is empty we have reached the end of the headers.
			if(lineLen == 0) {
				// Increment pos to move past the empty line.
				*pos += 2;
				return Void();
			}

			int nameEnd=-1, valueStart=-1, valueEnd=-1;
			int len = -1;

			// Read header of the form "Name: Value\n"
			// Note that multi line header values are not supported here.
			// Format string breaks down as follows:
			//   %*[^:]%n      Some characters other than ':' which are discarded, save the end position
			//   :%*[ \t]%n    A colon followed by 0 or more spaces or tabs only, save the end position
			//   %*[^\r]%n     Some characters other than \r which are discarded, save the end position
			//   %*1[\r]       Exactly one \r
			//   %*1[\n]       Exactly one \n
			//   %n            Save final end position
			if(sscanf(buf->c_str() + *pos, "%*[^:]%n:%*[ \t]%n%*[^\r]%n%*1[\r]%*1[\n]%n", &nameEnd, &valueStart, &valueEnd, &len) >= 0 && len > 0) {
				const std::string name(buf->substr(*pos, nameEnd));
				const std::string value(buf->substr(*pos + valueStart, valueEnd - valueStart));
				(*headers)[name] = value;
				*pos += len;
				len = -1;
			}
			else // Malformed header line (at least according to this simple parsing)
				throw http_bad_response();
		}
	}

	// Reads an HTTP response from a network connection
	// If the connection fails while being read the exception will emitted
	// If the response is not parseable or complete in some way, http_bad_response will be thrown
	ACTOR Future<Void> read_http_response(Reference<HTTP::Response> r, Reference<IConnection> conn, bool header_only) {
		state std::string buf;
		state size_t pos = 0;

		// Read HTTP reponse code and version line
		size_t lineLen = wait(read_delimited_into_string(conn, "\r\n", &buf, pos));

		int reachedEnd = -1;
		sscanf(buf.c_str() + pos, "HTTP/%f %d%n", &r->version, &r->code, &reachedEnd);
		if(reachedEnd < 0)
			throw http_bad_response();

		// Move position past the line found and the delimiter length
		pos += lineLen + 2;

		// Read headers
		r->headers.clear();

		Void _ = wait(read_http_response_headers(conn, &r->headers, &buf, &pos));

		auto i = r->headers.find("Content-Length");
		if(i != r->headers.end())
			r->contentLen = atoi(i->second.c_str());
		else
			r->contentLen = -1;  // Content length unknown

		state std::string transferEncoding;
		i = r->headers.find("Transfer-Encoding");
		if(i != r->headers.end())
			transferEncoding = i->second;

		r->content.clear();

		// If this is supposed to be a header-only response and the buffer has been fully processed then stop.  Otherwise, there must be response content.
		if(header_only && pos == buf.size())
			return Void();

		// There should be content (or at least metadata describing that there is no content.
		// Chunked transfer and 'normal' mode (content length given, data in one segment after headers) are supported.
		if(r->contentLen >= 0) {
			// Use response content as the buffer so there's no need to copy it later.
			r->content = buf.substr(pos);
			pos = 0;

			// Read until there are at least contentLen bytes available at pos
			Void _ = wait(read_fixed_into_string(conn, r->contentLen, &r->content, pos));

			// There shouldn't be any bytes after content.
			if(r->content.size() != r->contentLen)
				throw http_bad_response();
		}
		else if(transferEncoding == "chunked") {
			// Copy remaining buffer data to content which will now be the read buffer for the chunk encoded data.
			// Overall this will be fairly efficient since most bytes will only be written once but some bytes will
			// have to be copied forward in the buffer when removing chunk overhead bytes.
			r->content = buf.substr(pos);
			pos = 0;

			loop {
				// Read the line that contains the chunk length as text in hex
				size_t lineLen = wait(read_delimited_into_string(conn, "\r\n", &r->content, pos));
				state int chunkLen = strtol(r->content.substr(pos, lineLen).c_str(), NULL, 16);

				// Instead of advancing pos, erase the chunk length header line (line length + delimiter size) from the content buffer
				r->content.erase(pos, lineLen + 2);

				// If chunkLen is 0 then this marks the end of the content chunks.
				if(chunkLen == 0)
					break;

				// Read (if needed) until chunkLen bytes are available at pos, then advance pos by chunkLen
				Void _ = wait(read_fixed_into_string(conn, chunkLen, &r->content, pos));
				pos += chunkLen;

				// Read the final empty line at the end of the chunk (the required "\r\n" after the chunk bytes)
				size_t lineLen = wait(read_delimited_into_string(conn, "\r\n", &r->content, pos));
				if(lineLen != 0)
					throw http_bad_response();

				// Instead of advancing pos, erase the empty line from the content buffer
				r->content.erase(pos, 2);
			}

			// The content buffer now contains the de-chunked, contiguous content at position 0 to pos.  Save this length.
			r->contentLen = pos;

			// Next is the post-chunk header block, so read that.
			Void _ = wait(read_http_response_headers(conn, &r->headers, &r->content, &pos));

			// If the header parsing did not consume all of the buffer then something is wrong
			if(pos != r->content.size())
				throw http_bad_response();

			// Now truncate the buffer to just the dechunked contiguous content.
			r->content.erase(r->contentLen);
		}
		else {
			// Some unrecogize response content scheme is being used.
			throw http_bad_response();
		}

		// If there is actual response content, check the MD5 sum against the Content-MD5 response header
		if(r->content.size() > 0)
			if(!r->verifyMD5(false))  // false arg means do not fail if the Content-MD5 header is missing.
				throw http_bad_response();

		return Void();
	}

	Future<Void> HTTP::Response::read(Reference<IConnection> conn, bool header_only) {
		return read_http_response(Reference<HTTP::Response>::addRef(this), conn, header_only);
	}

	// Do a request, get a Response.
	// Request content is provided as UnsentPacketQueue *pContent which will be depleted as bytes are sent but the queue itself must live for the life of this actor
	// and be destroyed by the caller
	// TODO:  pSent is very hackish, do something better.
	ACTOR Future<Reference<HTTP::Response>> doRequest(Reference<IConnection> conn, std::string verb, std::string resource, HTTP::Headers headers, UnsentPacketQueue *pContent, int contentLen, Reference<IRateControl> sendRate, int64_t *pSent, Reference<IRateControl> recvRate) {
		state UnsentPacketQueue empty;
		if(pContent == NULL)
			pContent = &empty;

		state bool earlyResponse = false;
		state int total_sent = 0;

		try {
			// Write headers to a packet buffer chain
			PacketBuffer *pFirst = new PacketBuffer();
			PacketBuffer *pLast = writeRequestHeader(verb, resource, headers, pFirst);
			// Prepend headers to content packer buffer chain
			pContent->prependWriteBuffer(pFirst, pLast);

			if(CLIENT_KNOBS->HTTP_VERBOSE_LEVEL > 1)
				printf("[%s] HTTP starting %s %s ContentLen:%d\n", conn->getDebugID().toString().c_str(), verb.c_str(), resource.c_str(), contentLen);
			if(CLIENT_KNOBS->HTTP_VERBOSE_LEVEL > 2) {
				for(auto h : headers)
					printf("Request Header: %s: %s\n", h.first.c_str(), h.second.c_str());
			}

			state Reference<HTTP::Response> r(new HTTP::Response());
			state Future<Void> responseReading = r->read(conn, verb == "HEAD" || verb == "DELETE");

			state double send_start = timer();

			loop {
				Void _ = wait(conn->onWritable());
				Void _ = wait( delay( 0, TaskWriteSocket ) );

				// If we already got a response, before finishing sending the request, then close the connection,
				// set the Connection header to "close" as a hint to the caller that this connection can't be used
				// again, and break out of the send loop.
				if(responseReading.isReady()) {
					conn->close();
					r->headers["Connection"] = "close";
					earlyResponse = true;
					break;
				}

				state int trySend = CLIENT_KNOBS->HTTP_SEND_SIZE;
				Void _ = wait(sendRate->getAllowance(trySend));
				int len = conn->write(pContent->getUnsent(), trySend);
				if(pSent != nullptr)
					*pSent += len;
				sendRate->returnUnused(trySend - len);
				total_sent += len;
				pContent->sent(len);
				if(pContent->empty())
					break;
			}

			Void _ = wait(responseReading);

			double elapsed = timer() - send_start;
			if(CLIENT_KNOBS->HTTP_VERBOSE_LEVEL > 0)
				printf("[%s] HTTP code=%d early=%d, time=%fs %s %s contentLen=%d [%d out, response content len %d]\n",
					conn->getDebugID().toString().c_str(), r->code, earlyResponse, elapsed, verb.c_str(), resource.c_str(), contentLen, total_sent, (int)r->contentLen);
			if(CLIENT_KNOBS->HTTP_VERBOSE_LEVEL > 2)
				printf("[%s] HTTP RESPONSE:  %s %s\n%s\n", conn->getDebugID().toString().c_str(), verb.c_str(), resource.c_str(), r->toString().c_str());
			return r;
		} catch(Error &e) {
			double elapsed = timer() - send_start;
			if(CLIENT_KNOBS->HTTP_VERBOSE_LEVEL > 0)
				printf("[%s] HTTP *ERROR*=%s early=%d, time=%fs %s %s contentLen=%d [%d out]\n",
					conn->getDebugID().toString().c_str(), e.name(), earlyResponse, elapsed, verb.c_str(), resource.c_str(), contentLen, total_sent);
			throw;
		}
	}

}