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1 : : // Copyright (c) 2020-2022 The Bitcoin Core developers
2 : : // Distributed under the MIT software license, see the accompanying
3 : : // file COPYING or http://www.opensource.org/licenses/mit-license.php.
4 : :
5 : : #ifndef BITCOIN_UTIL_SOCK_H
6 : : #define BITCOIN_UTIL_SOCK_H
7 : :
8 : : #include <compat/compat.h>
9 : : #include <util/threadinterrupt.h>
10 : : #include <util/time.h>
11 : :
12 : : #include <chrono>
13 : : #include <memory>
14 : : #include <string>
15 : : #include <unordered_map>
16 : :
17 : : /**
18 : : * Maximum time to wait for I/O readiness.
19 : : * It will take up until this time to break off in case of an interruption.
20 : : */
21 : : static constexpr auto MAX_WAIT_FOR_IO = 1s;
22 : :
23 : : /**
24 : : * RAII helper class that manages a socket. Mimics `std::unique_ptr`, but instead of a pointer it
25 : : * contains a socket and closes it automatically when it goes out of scope.
26 : : */
27 : : class Sock
28 : : {
29 : : public:
30 : : /**
31 : : * Default constructor, creates an empty object that does nothing when destroyed.
32 : : */
33 : : Sock();
34 : :
35 : : /**
36 : : * Take ownership of an existent socket.
37 : : */
38 : : explicit Sock(SOCKET s);
39 : :
40 : : /**
41 : : * Copy constructor, disabled because closing the same socket twice is undesirable.
42 : : */
43 : : Sock(const Sock&) = delete;
44 : :
45 : : /**
46 : : * Move constructor, grab the socket from another object and close ours (if set).
47 : : */
48 : : Sock(Sock&& other);
49 : :
50 : : /**
51 : : * Destructor, close the socket or do nothing if empty.
52 : : */
53 : : virtual ~Sock();
54 : :
55 : : /**
56 : : * Copy assignment operator, disabled because closing the same socket twice is undesirable.
57 : : */
58 : : Sock& operator=(const Sock&) = delete;
59 : :
60 : : /**
61 : : * Move assignment operator, grab the socket from another object and close ours (if set).
62 : : */
63 : : virtual Sock& operator=(Sock&& other);
64 : :
65 : : /**
66 : : * Get the value of the contained socket.
67 : : * @return socket or INVALID_SOCKET if empty
68 : : */
69 : : [[nodiscard]] virtual SOCKET Get() const;
70 : :
71 : : /**
72 : : * send(2) wrapper. Equivalent to `send(this->Get(), data, len, flags);`. Code that uses this
73 : : * wrapper can be unit tested if this method is overridden by a mock Sock implementation.
74 : : */
75 : : [[nodiscard]] virtual ssize_t Send(const void* data, size_t len, int flags) const;
76 : :
77 : : /**
78 : : * recv(2) wrapper. Equivalent to `recv(this->Get(), buf, len, flags);`. Code that uses this
79 : : * wrapper can be unit tested if this method is overridden by a mock Sock implementation.
80 : : */
81 : : [[nodiscard]] virtual ssize_t Recv(void* buf, size_t len, int flags) const;
82 : :
83 : : /**
84 : : * connect(2) wrapper. Equivalent to `connect(this->Get(), addr, addrlen)`. Code that uses this
85 : : * wrapper can be unit tested if this method is overridden by a mock Sock implementation.
86 : : */
87 : : [[nodiscard]] virtual int Connect(const sockaddr* addr, socklen_t addr_len) const;
88 : :
89 : : /**
90 : : * bind(2) wrapper. Equivalent to `bind(this->Get(), addr, addr_len)`. Code that uses this
91 : : * wrapper can be unit tested if this method is overridden by a mock Sock implementation.
92 : : */
93 : : [[nodiscard]] virtual int Bind(const sockaddr* addr, socklen_t addr_len) const;
94 : :
95 : : /**
96 : : * listen(2) wrapper. Equivalent to `listen(this->Get(), backlog)`. Code that uses this
97 : : * wrapper can be unit tested if this method is overridden by a mock Sock implementation.
98 : : */
99 : : [[nodiscard]] virtual int Listen(int backlog) const;
100 : :
101 : : /**
102 : : * accept(2) wrapper. Equivalent to `std::make_unique<Sock>(accept(this->Get(), addr, addr_len))`.
103 : : * Code that uses this wrapper can be unit tested if this method is overridden by a mock Sock
104 : : * implementation.
105 : : * The returned unique_ptr is empty if `accept()` failed in which case errno will be set.
106 : : */
107 : : [[nodiscard]] virtual std::unique_ptr<Sock> Accept(sockaddr* addr, socklen_t* addr_len) const;
108 : :
109 : : /**
110 : : * getsockopt(2) wrapper. Equivalent to
111 : : * `getsockopt(this->Get(), level, opt_name, opt_val, opt_len)`. Code that uses this
112 : : * wrapper can be unit tested if this method is overridden by a mock Sock implementation.
113 : : */
114 : : [[nodiscard]] virtual int GetSockOpt(int level,
115 : : int opt_name,
116 : : void* opt_val,
117 : : socklen_t* opt_len) const;
118 : :
119 : : /**
120 : : * setsockopt(2) wrapper. Equivalent to
121 : : * `setsockopt(this->Get(), level, opt_name, opt_val, opt_len)`. Code that uses this
122 : : * wrapper can be unit tested if this method is overridden by a mock Sock implementation.
123 : : */
124 : : [[nodiscard]] virtual int SetSockOpt(int level,
125 : : int opt_name,
126 : : const void* opt_val,
127 : : socklen_t opt_len) const;
128 : :
129 : : /**
130 : : * getsockname(2) wrapper. Equivalent to
131 : : * `getsockname(this->Get(), name, name_len)`. Code that uses this
132 : : * wrapper can be unit tested if this method is overridden by a mock Sock implementation.
133 : : */
134 : : [[nodiscard]] virtual int GetSockName(sockaddr* name, socklen_t* name_len) const;
135 : :
136 : : /**
137 : : * Set the non-blocking option on the socket.
138 : : * @return true if set successfully
139 : : */
140 : : [[nodiscard]] virtual bool SetNonBlocking() const;
141 : :
142 : : /**
143 : : * Check if the underlying socket can be used for `select(2)` (or the `Wait()` method).
144 : : * @return true if selectable
145 : : */
146 : : [[nodiscard]] virtual bool IsSelectable() const;
147 : :
148 : : using Event = uint8_t;
149 : :
150 : : /**
151 : : * If passed to `Wait()`, then it will wait for readiness to read from the socket.
152 : : */
153 : : static constexpr Event RECV = 0b001;
154 : :
155 : : /**
156 : : * If passed to `Wait()`, then it will wait for readiness to send to the socket.
157 : : */
158 : : static constexpr Event SEND = 0b010;
159 : :
160 : : /**
161 : : * Ignored if passed to `Wait()`, but could be set in the occurred events if an
162 : : * exceptional condition has occurred on the socket or if it has been disconnected.
163 : : */
164 : : static constexpr Event ERR = 0b100;
165 : :
166 : : /**
167 : : * Wait for readiness for input (recv) or output (send).
168 : : * @param[in] timeout Wait this much for at least one of the requested events to occur.
169 : : * @param[in] requested Wait for those events, bitwise-or of `RECV` and `SEND`.
170 : : * @param[out] occurred If not nullptr and the function returns `true`, then this
171 : : * indicates which of the requested events occurred (`ERR` will be added, even if
172 : : * not requested, if an exceptional event occurs on the socket).
173 : : * A timeout is indicated by return value of `true` and `occurred` being set to 0.
174 : : * @return true on success (or timeout, if `occurred` of 0 is returned), false otherwise
175 : : */
176 : : [[nodiscard]] virtual bool Wait(std::chrono::milliseconds timeout,
177 : : Event requested,
178 : : Event* occurred = nullptr) const;
179 : :
180 : : /**
181 : : * Auxiliary requested/occurred events to wait for in `WaitMany()`.
182 : : */
183 : : struct Events {
184 : 0 : explicit Events(Event req) : requested{req} {}
185 : : Event requested;
186 : 0 : Event occurred{0};
187 : : };
188 : :
189 : : struct HashSharedPtrSock {
190 : 0 : size_t operator()(const std::shared_ptr<const Sock>& s) const
191 : : {
192 [ # # ]: 0 : return s ? s->m_socket : std::numeric_limits<SOCKET>::max();
193 : : }
194 : : };
195 : :
196 : : struct EqualSharedPtrSock {
197 : 0 : bool operator()(const std::shared_ptr<const Sock>& lhs,
198 : : const std::shared_ptr<const Sock>& rhs) const
199 : : {
200 [ # # ][ # # ]: 0 : if (lhs && rhs) {
201 : 0 : return lhs->m_socket == rhs->m_socket;
202 : : }
203 [ # # ][ # # ]: 0 : if (!lhs && !rhs) {
204 : 0 : return true;
205 : : }
206 : 0 : return false;
207 : 0 : }
208 : : };
209 : :
210 : : /**
211 : : * On which socket to wait for what events in `WaitMany()`.
212 : : * The `shared_ptr` is copied into the map to ensure that the `Sock` object
213 : : * is not destroyed (its destructor would close the underlying socket).
214 : : * If this happens shortly before or after we call `poll(2)` and a new
215 : : * socket gets created under the same file descriptor number then the report
216 : : * from `WaitMany()` will be bogus.
217 : : */
218 : : using EventsPerSock = std::unordered_map<std::shared_ptr<const Sock>, Events, HashSharedPtrSock, EqualSharedPtrSock>;
219 : :
220 : : /**
221 : : * Same as `Wait()`, but wait on many sockets within the same timeout.
222 : : * @param[in] timeout Wait this long for at least one of the requested events to occur.
223 : : * @param[in,out] events_per_sock Wait for the requested events on these sockets and set
224 : : * `occurred` for the events that actually occurred.
225 : : * @return true on success (or timeout, if all `what[].occurred` are returned as 0),
226 : : * false otherwise
227 : : */
228 : : [[nodiscard]] virtual bool WaitMany(std::chrono::milliseconds timeout,
229 : : EventsPerSock& events_per_sock) const;
230 : :
231 : : /* Higher level, convenience, methods. These may throw. */
232 : :
233 : : /**
234 : : * Send the given data, retrying on transient errors.
235 : : * @param[in] data Data to send.
236 : : * @param[in] timeout Timeout for the entire operation.
237 : : * @param[in] interrupt If this is signaled then the operation is canceled.
238 : : * @throws std::runtime_error if the operation cannot be completed. In this case only some of
239 : : * the data will be written to the socket.
240 : : */
241 : : virtual void SendComplete(const std::string& data,
242 : : std::chrono::milliseconds timeout,
243 : : CThreadInterrupt& interrupt) const;
244 : :
245 : : /**
246 : : * Read from socket until a terminator character is encountered. Will never consume bytes past
247 : : * the terminator from the socket.
248 : : * @param[in] terminator Character up to which to read from the socket.
249 : : * @param[in] timeout Timeout for the entire operation.
250 : : * @param[in] interrupt If this is signaled then the operation is canceled.
251 : : * @param[in] max_data The maximum amount of data (in bytes) to receive. If this many bytes
252 : : * are received and there is still no terminator, then this method will throw an exception.
253 : : * @return The data that has been read, without the terminating character.
254 : : * @throws std::runtime_error if the operation cannot be completed. In this case some bytes may
255 : : * have been consumed from the socket.
256 : : */
257 : : [[nodiscard]] virtual std::string RecvUntilTerminator(uint8_t terminator,
258 : : std::chrono::milliseconds timeout,
259 : : CThreadInterrupt& interrupt,
260 : : size_t max_data) const;
261 : :
262 : : /**
263 : : * Check if still connected.
264 : : * @param[out] errmsg The error string, if the socket has been disconnected.
265 : : * @return true if connected
266 : : */
267 : : [[nodiscard]] virtual bool IsConnected(std::string& errmsg) const;
268 : :
269 : : protected:
270 : : /**
271 : : * Contained socket. `INVALID_SOCKET` designates the object is empty.
272 : : */
273 : : SOCKET m_socket;
274 : :
275 : : private:
276 : : /**
277 : : * Close `m_socket` if it is not `INVALID_SOCKET`.
278 : : */
279 : : void Close();
280 : : };
281 : :
282 : : /** Return readable error string for a network error code */
283 : : std::string NetworkErrorString(int err);
284 : :
285 : : #endif // BITCOIN_UTIL_SOCK_H
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