RequestParser.cpp

/*
   Copyright (c) 2011, Chris Pearce

   Redistribution and use in source and binary forms, with or without
   modification, are permitted provided that the following conditions
   are met:

   - Redistributions of source code must retain the above copyright
   notice, this list of conditions and the following disclaimer.

   - Redistributions in binary form must reproduce the above copyright
   notice, this list of conditions and the following disclaimer in the
   documentation and/or other materials provided with the distribution.

   - Neither the name of Chris Pearce nor the names of its
   contributors may be used to endorse or promote products derived from
   this software without specific prior written permission.

   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
   PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE ORGANISATION OR
   CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
   EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
   PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
   PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
   LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
   NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
   SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

#include <assert.h>
#include <stdio.h>
#include <stdlib.h>

#include <iostream>

#include "RequestParser.h"

static int gCount = 0;

RequestParser::RequestParser()
  : start(0),
    complete(false),
    method(UNKNOWN),
    rangeStart(-1),
    rangeEnd(-1),
    hasRange(false),
    id(gCount++)
{
}

void RequestParser::Add(const char* buf, unsigned len) {
  assert(!complete);
  string str(buf, len);
  request += str;
  const char* linebr = "\r\n";
  assert(linebr[0] == 13);
  assert(linebr[1] == 10);
  // Continue to parse request.
  while (start < request.size()) {
    size_t end = request.find(linebr, start, 2);
    if (end == string::npos)
      break;
    if (start == end)
      complete = true;
    string l = string(request, start, end - start);
    Parse(l);
    start = end + 2;
  }
  cout << "Request " << id << std::endl << buf;
}

#ifdef _DEBUG
void RequestParser::Test() {
  assert(ExtractMethod("GET / HTTP1.1") == GET);
  assert(ExtractMethod("HEAD / HTTP1.1") == HEAD);
  assert(ExtractMethod("POST / HTTP1.1") == POST);
  assert(ExtractMethod("Error / HTTP1.1") == UNKNOWN);

  assert(ExtractTarget("GET / HTTP1.1") == "");
  assert(ExtractTarget("GET // HTTP1.1") == "");
  assert(ExtractTarget("GET /// HTTP1.1") == "");
  assert(ExtractTarget("GET /dir/file.txt HTTP1.1") == "dir/file.txt");
  assert(ExtractTarget("GET /dir/file.txt?params HTTP1.1") == "dir/file.txt");
  assert(ExtractTarget("GET /?params HTTP1.1") == "");
  assert(ExtractTarget("GET //?params HTTP1.1") == "");

  assert(Flatten(ExtractQueryParams("GET / HTTP1.1")) == "");

  assert(Flatten(ExtractQueryParams("GET // HTTP1.1")) == "");
  assert(Flatten(ExtractQueryParams("GET /// HTTP1.1")) == "");
  assert(Flatten(ExtractQueryParams("GET /dir/file.txt HTTP1.1")) == "");
  assert(Flatten(ExtractQueryParams("GET /dir/file.txt? HTTP1.1")) == "");
  assert(Flatten(ExtractQueryParams("GET /dir/file.txt?params HTTP1.1")) == "params=''");
  assert(Flatten(ExtractQueryParams("GET /dir/file.txt?param1&param2&param3 HTTP1.1")) == "param1='' param2='' param3=''");
  assert(Flatten(ExtractQueryParams("GET /dir/file.txt?param1=val1&param2=val2&param3=val3 HTTP1.1")) == "param1='val1' param2='val2' param3='val3'");
  assert(Flatten(ExtractQueryParams("GET /?params HTTP1.1")) == "params=''");
  assert(Flatten(ExtractQueryParams("GET /? HTTP1.1")) == "");
  assert(Flatten(ExtractQueryParams("GET //?params HTTP1.1")) == "params=''");

  assert(TestRange(true, "Range: bytes=0-1024", 0, 1024));
  assert(TestRange(false, "Range: time=0-1024", 0, 0));
  assert(TestRange(true, "Range: bytes=0-", 0, -1));
  assert(TestRange(true, "Range: bytes=1024-", 1024, -1));
  assert(TestRange(true, "Range: bytes=232128512-", 232128512, -1));
}
#endif

void RequestParser::GetRange(int64_t& start, int64_t& end) const {
  start = rangeStart;
  end = rangeEnd;
}

bool RequestParser::TestRange(bool expected,
                              const string& s,
                              int64_t expStart,
                              int64_t expEnd)
{
  int64_t start=-2, end=-2;
  bool r = ParseRange(s, start, end);
  return r == expected &&
          (!expected || start == expStart && end == expEnd);
}

void RequestParser::Parse(const string& s) {
  if (start == 0) {
    // Request line.
    ParseRequestLine(s);
  } else if (s.find("Range") == 0) {
    int64_t start,end;
    if (ParseRange(s, start, end)) {
      rangeStart = start;
      rangeEnd = end;
      hasRange = true;
    }
  }
}

bool RequestParser::ParseRange(const string& s,
                               int64_t& start,
                               int64_t& end)
{
  // Range: bytes=start,end
  size_t sp = s.find(" ");
  size_t eq = s.find("=");
  if (sp == string::npos || eq == string::npos)
    return false;
  string bytes(s, sp + 1, eq - sp - 1);
  if (bytes != "bytes") {
    // The space is not followed by "bytes=", this is an invalid range param.
    return false;
  }

  string range(s, eq + 1);
  size_t dash = range.find("-");
  if (dash == string::npos)
    return false;
  string startStr(range, 0, dash);
  string endStr(range, dash + 1);

  start = atoll(startStr.c_str());
  if (endStr != "") {
    end = atoll(endStr.c_str());
  } else {
    end = -1;
  }

  return true;
}

eMethod RequestParser::ExtractMethod(const string& request) {
  size_t sp = request.find(" ");
  string m(request, 0, sp);
  if (m == "GET")
    return GET;
  else if (m == "HEAD")
    return HEAD;
  else if (m == "POST")
    return POST;
  return UNKNOWN;
}

string RequestParser::ExtractTarget(const string& request) {
  size_t start = request.find("/") + 1;
  size_t query = request.find("?", start); // Location of query params.
  size_t end = (query != string::npos) ? query : request.find(" ", start);
  // Remove trailing slashes.
  while (end > start && request.at(end - 1) == '/') {
    end--;
  }
  return string(request, start, end - start);
}

map<string, string> RequestParser::ExtractQueryParams(const string& request) {
  map<string,string> m;
  size_t query = request.find("?");
  if (query == string::npos)
    return m;
  size_t start = query + 1;
  size_t end = request.find(" ", start);
  vector<string> v;
  Tokenize(string(request, start, end - start), v, "&");
  for (unsigned i=0; i<v.size(); i++) {
    size_t eq = v[i].find("=");
    string key;
    string value;
    if (eq == string::npos) {
      key = v[i];
      value = "";
    } else {
      key = string(v[i], 0, eq);
      value = string(v[i], eq + 1, v[i].size() - eq - 1);
    }
    m[key] = value;
  }
  return m;
}

void RequestParser::ParseRequestLine(const string& request) {
  // Extract method.
  method = ExtractMethod(request);
  target = ExtractTarget(request);
  params = ExtractQueryParams(request);
  //printf("Target: '%s'\n", target.c_str());
  //printf("Params: '%s'\n", Flatten(params).c_str());
}