/proc/self/cwd/src/http_template.cc

Source (jump to first uncovered line)
// Copyright 2016 Google Inc. All Rights Reserved.
//
// 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 "grpc_transcoding/http_template.h"

#include <string>
#include <vector>

namespace google {
namespace grpc {
namespace transcoding {

namespace {

// TODO: implement an error sink.

// HTTP Template Grammar:
// Questions:
//   - what are the constraints on LITERAL and IDENT?
//   - what is the character set for the grammar?
//
// Template = "/" | "/" Segments [ Verb ] ;
// Segments = Segment { "/" Segment } ;
// Segment  = "*" | "**" | LITERAL | Variable ;
// Variable = "{" FieldPath [ "=" Segments ] "}" ;
// FieldPath = IDENT { "." IDENT } ;
// Verb     = ":" LITERAL ;
class Parser {
 public:
  Parser(const std::string &input)
      : input_(input), tb_(0), te_(0), in_variable_(false) {}

  bool Parse() {
    if (!ParseTemplate() || !ConsumedAllInput()) {
      return false;
    }
    PostProcessVariables();
    return true;
  }

  std::vector<std::string> &segments() { return segments_; }
  std::string &verb() { return verb_; }
  std::vector<HttpTemplate::Variable> &variables() { return variables_; }

  // only constant path segments are allowed after '**'.
  bool ValidateParts() {
    bool found_wild_card = false;
    for (size_t i = 0; i < segments_.size(); i++) {
      if (!found_wild_card) {
        if (segments_[i] == HttpTemplate::kWildCardPathKey) {
          found_wild_card = true;
        }
      } else if (segments_[i] == HttpTemplate::kSingleParameterKey ||
                 segments_[i] == HttpTemplate::kWildCardPathPartKey ||
                 segments_[i] == HttpTemplate::kWildCardPathKey) {
        return false;
      }
    }
    return true;
  }

 private:
  // Template = "/" Segments [ Verb ] ;
  bool ParseTemplate() {
    if (!Consume('/')) {
      // Expected '/'
      return false;
    }
    if (!ParseSegments()) {
      return false;
    }

    if (EnsureCurrent() && current_char() == ':') {
      if (!ParseVerb()) {
        return false;
      }
    }
    return true;
  }

  // Segments = Segment { "/" Segment } ;
  bool ParseSegments() {
    if (!ParseSegment()) {
      return false;
    }

    for (;;) {
      if (!Consume('/')) break;
      if (!ParseSegment()) {
        return false;
      }
    }

    return true;
  }

  // Segment  = "*" | "**" | LITERAL | Variable ;
  bool ParseSegment() {
    if (!EnsureCurrent()) {
      return false;
    }
    switch (current_char()) {
      case '*': {
        Consume('*');
        if (Consume('*')) {
          // **
          segments_.push_back("**");
          if (in_variable_) {
            return MarkVariableHasWildCardPath();
          }
          return true;
        } else {
          segments_.push_back("*");
          return true;
        }
      }

      case '{':
        return ParseVariable();
      default:
        return ParseLiteralSegment();
    }
  }

  // Variable = "{" FieldPath [ "=" Segments ] "}" ;
  bool ParseVariable() {
    if (!Consume('{')) {
      return false;
    }
    if (!StartVariable()) {
      return false;
    }
    if (!ParseFieldPath()) {
      return false;
    }
    if (Consume('=')) {
      if (!ParseSegments()) {
        return false;
      }
    } else {
      // {field_path} is equivalent to {field_path=*}
      segments_.push_back("*");
    }
    if (!EndVariable()) {
      return false;
    }
    if (!Consume('}')) {
      return false;
    }
    return true;
  }

  bool ParseLiteralSegment() {
    std::string ls;
    if (!ParseLiteral(&ls)) {
      return false;
    }
    segments_.push_back(ls);
    return true;
  }

  // FieldPath = IDENT { "." IDENT } ;
  bool ParseFieldPath() {
    if (!ParseIdentifier()) {
      return false;
    }
    while (Consume('.')) {
      if (!ParseIdentifier()) {
        return false;
      }
    }
    return true;
  }

  // Verb     = ":" LITERAL ;
  bool ParseVerb() {
    if (!Consume(':')) return false;
    if (!ParseLiteral(&verb_)) return false;
    return true;
  }

  bool ParseIdentifier() {
    std::string idf;

    // Initialize to false to handle empty literal.
    bool result = false;

    while (NextChar()) {
      char c;
      switch (c = current_char()) {
        case '.':
        case '}':
        case '=':
          return result && AddFieldIdentifier(std::move(idf));
        default:
          Consume(c);
          idf.push_back(c);
          break;
      }
      result = true;
    }
    return result && AddFieldIdentifier(std::move(idf));
  }

  bool ParseLiteral(std::string *lit) {
    if (!EnsureCurrent()) {
      return false;
    }

    // Initialize to false in case we encounter an empty literal.
    bool result = false;

    for (;;) {
      char c;
      switch (c = current_char()) {
        case '/':
        case ':':
        case '}':
          return result;
        default:
          Consume(c);
          lit->push_back(c);
          break;
      }

      result = true;

      if (!NextChar()) {
        break;
      }
    }
    return result;
  }

  bool Consume(char c) {
    if (tb_ >= te_ && !NextChar()) {
      return false;
    }
    if (current_char() != c) {
      return false;
    }
    tb_++;
    return true;
  }

  bool ConsumedAllInput() { return tb_ >= input_.size(); }

  bool EnsureCurrent() { return tb_ < te_ || NextChar(); }

  bool NextChar() {
    if (te_ < input_.size()) {
      te_++;
      return true;
    } else {
      return false;
    }
  }

  // Returns the character looked at.
  char current_char() const {
    return tb_ < te_ && te_ <= input_.size() ? input_[te_ - 1] : -1;
  }

  HttpTemplate::Variable &CurrentVariable() { return variables_.back(); }

  bool StartVariable() {
    if (!in_variable_) {
      variables_.push_back(HttpTemplate::Variable{});
      CurrentVariable().start_segment = segments_.size();
      CurrentVariable().has_wildcard_path = false;
      in_variable_ = true;
      return true;
    } else {
      // nested variables are not allowed
      return false;
    }
  }

  bool EndVariable() {
    if (in_variable_ && !variables_.empty()) {
      CurrentVariable().end_segment = segments_.size();
      in_variable_ = false;
      return ValidateVariable(CurrentVariable());
    } else {
      // something's wrong we're not in a variable
      return false;
    }
  }

  bool AddFieldIdentifier(std::string id) {
    if (in_variable_ && !variables_.empty()) {
      CurrentVariable().field_path.emplace_back(std::move(id));
      return true;
    } else {
      // something's wrong we're not in a variable
      return false;
    }
  }

  bool MarkVariableHasWildCardPath() {
    if (in_variable_ && !variables_.empty()) {
      CurrentVariable().has_wildcard_path = true;
      return true;
    } else {
      // something's wrong we're not in a variable
      return false;
    }
  }

  bool ValidateVariable(const HttpTemplate::Variable &var) {
    return !var.field_path.empty() && (var.start_segment < var.end_segment) &&
           (var.end_segment <= static_cast<int>(segments_.size()));
  }

  void PostProcessVariables() {
    for (auto &var : variables_) {
      if (var.has_wildcard_path) {
        // if the variable contains a '**', store the end_positon
        // relative to the end, such that -1 corresponds to the end
        // of the path. As we only support fixed path after '**',
        // this will allow the matcher code to reconstruct the variable
        // value based on the url segments.
        var.end_segment = (var.end_segment - segments_.size() - 1);
      }
    }
  }

  const std::string &input_;

  // Token delimiter indexes
  size_t tb_;
  size_t te_;

  // are we in nested Segments of a variable?
  bool in_variable_;

  std::vector<std::string> segments_;
  std::string verb_;
  std::vector<HttpTemplate::Variable> variables_;
};

}  // namespace

const char HttpTemplate::kSingleParameterKey[] = "/.";

const char HttpTemplate::kWildCardPathPartKey[] = "*";

const char HttpTemplate::kWildCardPathKey[] = "**";

std::unique_ptr<HttpTemplate> HttpTemplate::Parse(const std::string &ht) {
  if (ht == "/") {
    return std::unique_ptr<HttpTemplate>(new HttpTemplate({}, {}, {}));
  }

  Parser p(ht);
  if (!p.Parse() || !p.ValidateParts()) {
    return nullptr;
  }

  return std::unique_ptr<HttpTemplate>(new HttpTemplate(
      std::move(p.segments()), std::move(p.verb()), std::move(p.variables())));
}

}  // namespace transcoding
}  // namespace grpc
}  // namespace google

Coverage Report

Created: 2025-08-29 06:15

Line	Count	Source (jump to first uncovered line)
1		// Copyright 2016 Google Inc. All Rights Reserved.
2		//
3		// Licensed under the Apache License, Version 2.0 (the "License");
4		// you may not use this file except in compliance with the License.
5		// You may obtain a copy of the License at
6		//
7		// http://www.apache.org/licenses/LICENSE-2.0
8		//
9		// Unless required by applicable law or agreed to in writing, software
10		// distributed under the License is distributed on an "AS IS" BASIS,
11		// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12		// See the License for the specific language governing permissions and
13		// limitations under the License.
14		//
15		////////////////////////////////////////////////////////////////////////////////
16		//
17		#include "grpc_transcoding/http_template.h"
18
19		#include <string>
20		#include <vector>
21
22		namespace google {
23		namespace grpc {
24		namespace transcoding {
25
26		namespace {
27
28		// TODO: implement an error sink.
29
30		// HTTP Template Grammar:
31		// Questions:
32		// - what are the constraints on LITERAL and IDENT?
33		// - what is the character set for the grammar?
34		//
35		// Template = "/" \| "/" Segments [ Verb ] ;
36		// Segments = Segment { "/" Segment } ;
37		// Segment = "" \| "*" \| LITERAL \| Variable ;
38		// Variable = "{" FieldPath [ "=" Segments ] "}" ;
39		// FieldPath = IDENT { "." IDENT } ;
40		// Verb = ":" LITERAL ;
41		class Parser {
42		public:
43		Parser(const std::string &input)
44	990	: input_(input), tb_(0), te_(0), in_variable_(false) {}
45
46	990	bool Parse() {
47	990	if (!ParseTemplate() \|\| !ConsumedAllInput()) {
48	504	return false;
49	504	}
50	486	PostProcessVariables();
51	486	return true;
52	990	}
53
54	412	std::vector<std::string> &segments() { return segments_; }
55	412	std::string &verb() { return verb_; }
56	412	std::vector<HttpTemplate::Variable> &variables() { return variables_; }
57
58		// only constant path segments are allowed after '**'.
59	486	bool ValidateParts() {
60	486	bool found_wild_card = false;
61	1.64M	for (size_t i = 0; i < segments_.size(); i++) {
62	1.64M	if (!found_wild_card) {
63	1.64M	if (segments_[i] == HttpTemplate::kWildCardPathKey) {
64	224	found_wild_card = true;
65	224	}
66	1.64M	} else if (segments_[i] == HttpTemplate::kSingleParameterKey \|\|
67	2.79k	segments_[i] == HttpTemplate::kWildCardPathPartKey \|\|
68	2.79k	segments_[i] == HttpTemplate::kWildCardPathKey) {
69	74	return false;
70	74	}
71	1.64M	}
72	412	return true;
73	486	}
74
75		private:
76		// Template = "/" Segments [ Verb ] ;
77	990	bool ParseTemplate() {
78	990	if (!Consume('/')) {
79		// Expected '/'
80	28	return false;
81	28	}
82	962	if (!ParseSegments()) {
83	342	return false;
84	342	}
85
86	620	if (EnsureCurrent() && current_char() == ':') {
87	58	if (!ParseVerb()) {
88	32	return false;
89	32	}
90	58	}
91	588	return true;
92	620	}
93
94		// Segments = Segment { "/" Segment } ;
95	8.61k	bool ParseSegments() {
96	8.61k	if (!ParseSegment()) {
97	126	return false;
98	126	}
99
100	4.47M	for (;;) {
101	4.47M	if (!Consume('/')) break;
102	4.46M	if (!ParseSegment()) {
103	242	return false;
104	242	}
105	4.46M	}
106
107	8.24k	return true;
108	8.49k	}
109
110		// Segment = "" \| "*" \| LITERAL \| Variable ;
111	4.47M	bool ParseSegment() {
112	4.47M	if (!EnsureCurrent()) {
113	44	return false;
114	44	}
115	4.47M	switch (current_char()) {
116	2.59M	case '*': {
117	2.59M	Consume('*');
118	2.59M	if (Consume('*')) {
119		// **
120	60.3k	segments_.push_back("**");
121	60.3k	if (in_variable_) {
122	10.6k	return MarkVariableHasWildCardPath();
123	10.6k	}
124	49.7k	return true;
125	2.53M	} else {
126	2.53M	segments_.push_back("*");
127	2.53M	return true;
128	2.53M	}
129	2.59M	}
130
131	299k	case '{':
132	299k	return ParseVariable();
133	1.57M	default:
134	1.57M	return ParseLiteralSegment();
135	4.47M	}
136	4.47M	}
137
138		// Variable = "{" FieldPath [ "=" Segments ] "}" ;
139	299k	bool ParseVariable() {
140	299k	if (!Consume('{')) {
141	0	return false;
142	0	}
143	299k	if (!StartVariable()) {
144	10	return false;
145	10	}
146	299k	if (!ParseFieldPath()) {
147	96	return false;
148	96	}
149	299k	if (Consume('=')) {
150	7.65k	if (!ParseSegments()) {
151	26	return false;
152	26	}
153	291k	} else {
154		// {field_path} is equivalent to {field_path=*}
155	291k	segments_.push_back("*");
156	291k	}
157	299k	if (!EndVariable()) {
158	0	return false;
159	0	}
160	299k	if (!Consume('}')) {
161	167	return false;
162	167	}
163	298k	return true;
164	299k	}
165
166	1.57M	bool ParseLiteralSegment() {
167	1.57M	std::string ls;
168	1.57M	if (!ParseLiteral(&ls)) {
169	25	return false;
170	25	}
171	1.57M	segments_.push_back(ls);
172	1.57M	return true;
173	1.57M	}
174
175		// FieldPath = IDENT { "." IDENT } ;
176	299k	bool ParseFieldPath() {
177	299k	if (!ParseIdentifier()) {
178	59	return false;
179	59	}
180	929k	while (Consume('.')) {
181	630k	if (!ParseIdentifier()) {
182	37	return false;
183	37	}
184	630k	}
185	299k	return true;
186	299k	}
187
188		// Verb = ":" LITERAL ;
189	58	bool ParseVerb() {
190	58	if (!Consume(':')) return false;
191	58	if (!ParseLiteral(&verb_)) return false;
192	26	return true;
193	58	}
194
195	929k	bool ParseIdentifier() {
196	929k	std::string idf;
197
198		// Initialize to false to handle empty literal.
199	929k	bool result = false;
200
201	7.24M	while (NextChar()) {
202	7.24M	char c;
203	7.24M	switch (c = current_char()) {
204	630k	case '.':
205	921k	case '}':
206	929k	case '=':
207	929k	return result && AddFieldIdentifier(std::move(idf));
208	6.31M	default:
209	6.31M	Consume(c);
210	6.31M	idf.push_back(c);
211	6.31M	break;
212	7.24M	}
213	6.31M	result = true;
214	6.31M	}
215	189	return result && AddFieldIdentifier(std::move(idf));
216	929k	}
217
218	1.57M	bool ParseLiteral(std::string *lit) {
219	1.57M	if (!EnsureCurrent()) {
220	30	return false;
221	30	}
222
223		// Initialize to false in case we encounter an empty literal.
224	1.57M	bool result = false;
225
226	29.0M	for (;;) {
227	29.0M	char c;
228	29.0M	switch (c = current_char()) {
229	1.57M	case '/':
230	1.57M	case ':':
231	1.57M	case '}':
232	1.57M	return result;
233	27.4M	default:
234	27.4M	Consume(c);
235	27.4M	lit->push_back(c);
236	27.4M	break;
237	29.0M	}
238
239	27.4M	result = true;
240
241	27.4M	if (!NextChar()) {
242	374	break;
243	374	}
244	27.4M	}
245	374	return result;
246	1.57M	}
247
248	45.2M	bool Consume(char c) {
249	45.2M	if (tb_ >= te_ && !NextChar()) {
250	940	return false;
251	940	}
252	45.2M	if (current_char() != c) {
253	3.13M	return false;
254	3.13M	}
255	42.1M	tb_++;
256	42.1M	return true;
257	45.2M	}
258
259	588	bool ConsumedAllInput() { return tb_ >= input_.size(); }
260
261	6.05M	bool EnsureCurrent() { return tb_ < te_ \|\| NextChar(); }
262
263	42.1M	bool NextChar() {
264	42.1M	if (te_ < input_.size()) {
265	42.1M	te_++;
266	42.1M	return true;
267	42.1M	} else {
268	2.03k	return false;
269	2.03k	}
270	42.1M	}
271
272		// Returns the character looked at.
273	85.9M	char current_char() const {
274	85.9M	return tb_ < te_ && te_ <= input_.size() ? input_[te_ - 1] : -1;
275	85.9M	}
276
277	2.13M	HttpTemplate::Variable &CurrentVariable() { return variables_.back(); }
278
279	299k	bool StartVariable() {
280	299k	if (!in_variable_) {
281	299k	variables_.push_back(HttpTemplate::Variable{});
282	299k	CurrentVariable().start_segment = segments_.size();
283	299k	CurrentVariable().has_wildcard_path = false;
284	299k	in_variable_ = true;
285	299k	return true;
286	299k	} else {
287		// nested variables are not allowed
288	10	return false;
289	10	}
290	299k	}
291
292	299k	bool EndVariable() {
293	299k	if (in_variable_ && !variables_.empty()) {
294	299k	CurrentVariable().end_segment = segments_.size();
295	299k	in_variable_ = false;
296	299k	return ValidateVariable(CurrentVariable());
297	299k	} else {
298		// something's wrong we're not in a variable
299	0	return false;
300	0	}
301	299k	}
302
303	929k	bool AddFieldIdentifier(std::string id) {
304	929k	if (in_variable_ && !variables_.empty()) {
305	929k	CurrentVariable().field_path.emplace_back(std::move(id));
306	929k	return true;
307	929k	} else {
308		// something's wrong we're not in a variable
309	0	return false;
310	0	}
311	929k	}
312
313	10.6k	bool MarkVariableHasWildCardPath() {
314	10.6k	if (in_variable_ && !variables_.empty()) {
315	10.6k	CurrentVariable().has_wildcard_path = true;
316	10.6k	return true;
317	10.6k	} else {
318		// something's wrong we're not in a variable
319	0	return false;
320	0	}
321	10.6k	}
322
323	299k	bool ValidateVariable(const HttpTemplate::Variable &var) {
324	299k	return !var.field_path.empty() && (var.start_segment < var.end_segment) &&
325	299k	(var.end_segment <= static_cast<int>(segments_.size()));
326	299k	}
327
328	486	void PostProcessVariables() {
329	257k	for (auto &var : variables_) {
330	257k	if (var.has_wildcard_path) {
331		// if the variable contains a '**', store the end_positon
332		// relative to the end, such that -1 corresponds to the end
333		// of the path. As we only support fixed path after '**',
334		// this will allow the matcher code to reconstruct the variable
335		// value based on the url segments.
336	1.03k	var.end_segment = (var.end_segment - segments_.size() - 1);
337	1.03k	}
338	257k	}
339	486	}
340
341		const std::string &input_;
342
343		// Token delimiter indexes
344		size_t tb_;
345		size_t te_;
346
347		// are we in nested Segments of a variable?
348		bool in_variable_;
349
350		std::vector<std::string> segments_;
351		std::string verb_;
352		std::vector<HttpTemplate::Variable> variables_;
353		};
354
355		} // namespace
356
357		const char HttpTemplate::kSingleParameterKey[] = "/.";
358
359		const char HttpTemplate::kWildCardPathPartKey[] = "*";
360
361		const char HttpTemplate::kWildCardPathKey[] = "**";
362
363	991	std::unique_ptr<HttpTemplate> HttpTemplate::Parse(const std::string &ht) {
364	991	if (ht == "/") {
365	1	return std::unique_ptr<HttpTemplate>(new HttpTemplate({}, {}, {}));
366	1	}
367
368	990	Parser p(ht);
369	990	if (!p.Parse() \|\| !p.ValidateParts()) {
370	578	return nullptr;
371	578	}
372
373	412	return std::unique_ptr<HttpTemplate>(new HttpTemplate(
374	412	std::move(p.segments()), std::move(p.verb()), std::move(p.variables())));
375	990	}
376
377		} // namespace transcoding
378		} // namespace grpc
379		} // namespace google