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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 and closes it automatically when it goes out of scope.
25 : : */
26 : : class Sock
27 : : {
28 : : public:
29 : : Sock() = delete;
30 : :
31 : : /**
32 : : * Take ownership of an existent socket.
33 : : */
34 : : explicit Sock(SOCKET s);
35 : :
36 : : /**
37 : : * Copy constructor, disabled because closing the same socket twice is undesirable.
38 : : */
39 : : Sock(const Sock&) = delete;
40 : :
41 : : /**
42 : : * Move constructor, grab the socket from another object and close ours (if set).
43 : : */
44 : : Sock(Sock&& other);
45 : :
46 : : /**
47 : : * Destructor, close the socket or do nothing if empty.
48 : : */
49 : : virtual ~Sock();
50 : :
51 : : /**
52 : : * Copy assignment operator, disabled because closing the same socket twice is undesirable.
53 : : */
54 : : Sock& operator=(const Sock&) = delete;
55 : :
56 : : /**
57 : : * Move assignment operator, grab the socket from another object and close ours (if set).
58 : : */
59 : : virtual Sock& operator=(Sock&& other);
60 : :
61 : : /**
62 : : * send(2) wrapper. Equivalent to `send(m_socket, data, len, flags);`. Code that uses this
63 : : * wrapper can be unit tested if this method is overridden by a mock Sock implementation.
64 : : */
65 : : [[nodiscard]] virtual ssize_t Send(const void* data, size_t len, int flags) const;
66 : :
67 : : /**
68 : : * recv(2) wrapper. Equivalent to `recv(m_socket, buf, len, flags);`. Code that uses this
69 : : * wrapper can be unit tested if this method is overridden by a mock Sock implementation.
70 : : */
71 : : [[nodiscard]] virtual ssize_t Recv(void* buf, size_t len, int flags) const;
72 : :
73 : : /**
74 : : * connect(2) wrapper. Equivalent to `connect(m_socket, addr, addrlen)`. Code that uses this
75 : : * wrapper can be unit tested if this method is overridden by a mock Sock implementation.
76 : : */
77 : : [[nodiscard]] virtual int Connect(const sockaddr* addr, socklen_t addr_len) const;
78 : :
79 : : /**
80 : : * bind(2) wrapper. Equivalent to `bind(m_socket, addr, addr_len)`. Code that uses this
81 : : * wrapper can be unit tested if this method is overridden by a mock Sock implementation.
82 : : */
83 : : [[nodiscard]] virtual int Bind(const sockaddr* addr, socklen_t addr_len) const;
84 : :
85 : : /**
86 : : * listen(2) wrapper. Equivalent to `listen(m_socket, backlog)`. Code that uses this
87 : : * wrapper can be unit tested if this method is overridden by a mock Sock implementation.
88 : : */
89 : : [[nodiscard]] virtual int Listen(int backlog) const;
90 : :
91 : : /**
92 : : * accept(2) wrapper. Equivalent to `std::make_unique<Sock>(accept(m_socket, addr, addr_len))`.
93 : : * Code that uses this wrapper can be unit tested if this method is overridden by a mock Sock
94 : : * implementation.
95 : : * The returned unique_ptr is empty if `accept()` failed in which case errno will be set.
96 : : */
97 : : [[nodiscard]] virtual std::unique_ptr<Sock> Accept(sockaddr* addr, socklen_t* addr_len) const;
98 : :
99 : : /**
100 : : * getsockopt(2) wrapper. Equivalent to
101 : : * `getsockopt(m_socket, level, opt_name, opt_val, opt_len)`. Code that uses this
102 : : * wrapper can be unit tested if this method is overridden by a mock Sock implementation.
103 : : */
104 : : [[nodiscard]] virtual int GetSockOpt(int level,
105 : : int opt_name,
106 : : void* opt_val,
107 : : socklen_t* opt_len) const;
108 : :
109 : : /**
110 : : * setsockopt(2) wrapper. Equivalent to
111 : : * `setsockopt(m_socket, 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 SetSockOpt(int level,
115 : : int opt_name,
116 : : const void* opt_val,
117 : : socklen_t opt_len) const;
118 : :
119 : : /**
120 : : * getsockname(2) wrapper. Equivalent to
121 : : * `getsockname(m_socket, name, name_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 GetSockName(sockaddr* name, socklen_t* name_len) const;
125 : :
126 : : /**
127 : : * Set the non-blocking option on the socket.
128 : : * @return true if set successfully
129 : : */
130 : : [[nodiscard]] virtual bool SetNonBlocking() const;
131 : :
132 : : /**
133 : : * Check if the underlying socket can be used for `select(2)` (or the `Wait()` method).
134 : : * @return true if selectable
135 : : */
136 : : [[nodiscard]] virtual bool IsSelectable() const;
137 : :
138 : : using Event = uint8_t;
139 : :
140 : : /**
141 : : * If passed to `Wait()`, then it will wait for readiness to read from the socket.
142 : : */
143 : : static constexpr Event RECV = 0b001;
144 : :
145 : : /**
146 : : * If passed to `Wait()`, then it will wait for readiness to send to the socket.
147 : : */
148 : : static constexpr Event SEND = 0b010;
149 : :
150 : : /**
151 : : * Ignored if passed to `Wait()`, but could be set in the occurred events if an
152 : : * exceptional condition has occurred on the socket or if it has been disconnected.
153 : : */
154 : : static constexpr Event ERR = 0b100;
155 : :
156 : : /**
157 : : * Wait for readiness for input (recv) or output (send).
158 : : * @param[in] timeout Wait this much for at least one of the requested events to occur.
159 : : * @param[in] requested Wait for those events, bitwise-or of `RECV` and `SEND`.
160 : : * @param[out] occurred If not nullptr and the function returns `true`, then this
161 : : * indicates which of the requested events occurred (`ERR` will be added, even if
162 : : * not requested, if an exceptional event occurs on the socket).
163 : : * A timeout is indicated by return value of `true` and `occurred` being set to 0.
164 : : * @return true on success (or timeout, if `occurred` of 0 is returned), false otherwise
165 : : */
166 : : [[nodiscard]] virtual bool Wait(std::chrono::milliseconds timeout,
167 : : Event requested,
168 : : Event* occurred = nullptr) const;
169 : :
170 : : /**
171 : : * Auxiliary requested/occurred events to wait for in `WaitMany()`.
172 : : */
173 : : struct Events {
174 : 340 : explicit Events(Event req) : requested{req} {}
175 : : Event requested;
176 : 170 : Event occurred{0};
177 : : };
178 : :
179 : : struct HashSharedPtrSock {
180 : 340 : size_t operator()(const std::shared_ptr<const Sock>& s) const
181 : : {
182 [ + - ]: 340 : return s ? s->m_socket : std::numeric_limits<SOCKET>::max();
183 : : }
184 : : };
185 : :
186 : : struct EqualSharedPtrSock {
187 : 170 : bool operator()(const std::shared_ptr<const Sock>& lhs,
188 : : const std::shared_ptr<const Sock>& rhs) const
189 : : {
190 [ + - ][ - + ]: 170 : if (lhs && rhs) {
191 : 170 : return lhs->m_socket == rhs->m_socket;
192 : : }
193 [ # # ][ # # ]: 0 : if (!lhs && !rhs) {
194 : 0 : return true;
195 : : }
196 : 0 : return false;
197 : 170 : }
198 : : };
199 : :
200 : : /**
201 : : * On which socket to wait for what events in `WaitMany()`.
202 : : * The `shared_ptr` is copied into the map to ensure that the `Sock` object
203 : : * is not destroyed (its destructor would close the underlying socket).
204 : : * If this happens shortly before or after we call `poll(2)` and a new
205 : : * socket gets created under the same file descriptor number then the report
206 : : * from `WaitMany()` will be bogus.
207 : : */
208 : : using EventsPerSock = std::unordered_map<std::shared_ptr<const Sock>, Events, HashSharedPtrSock, EqualSharedPtrSock>;
209 : :
210 : : /**
211 : : * Same as `Wait()`, but wait on many sockets within the same timeout.
212 : : * @param[in] timeout Wait this long for at least one of the requested events to occur.
213 : : * @param[in,out] events_per_sock Wait for the requested events on these sockets and set
214 : : * `occurred` for the events that actually occurred.
215 : : * @return true on success (or timeout, if all `what[].occurred` are returned as 0),
216 : : * false otherwise
217 : : */
218 : : [[nodiscard]] virtual bool WaitMany(std::chrono::milliseconds timeout,
219 : : EventsPerSock& events_per_sock) const;
220 : :
221 : : /* Higher level, convenience, methods. These may throw. */
222 : :
223 : : /**
224 : : * Send the given data, retrying on transient errors.
225 : : * @param[in] data Data to send.
226 : : * @param[in] timeout Timeout for the entire operation.
227 : : * @param[in] interrupt If this is signaled then the operation is canceled.
228 : : * @throws std::runtime_error if the operation cannot be completed. In this case only some of
229 : : * the data will be written to the socket.
230 : : */
231 : : virtual void SendComplete(const std::string& data,
232 : : std::chrono::milliseconds timeout,
233 : : CThreadInterrupt& interrupt) const;
234 : :
235 : : /**
236 : : * Read from socket until a terminator character is encountered. Will never consume bytes past
237 : : * the terminator from the socket.
238 : : * @param[in] terminator Character up to which to read from the socket.
239 : : * @param[in] timeout Timeout for the entire operation.
240 : : * @param[in] interrupt If this is signaled then the operation is canceled.
241 : : * @param[in] max_data The maximum amount of data (in bytes) to receive. If this many bytes
242 : : * are received and there is still no terminator, then this method will throw an exception.
243 : : * @return The data that has been read, without the terminating character.
244 : : * @throws std::runtime_error if the operation cannot be completed. In this case some bytes may
245 : : * have been consumed from the socket.
246 : : */
247 : : [[nodiscard]] virtual std::string RecvUntilTerminator(uint8_t terminator,
248 : : std::chrono::milliseconds timeout,
249 : : CThreadInterrupt& interrupt,
250 : : size_t max_data) const;
251 : :
252 : : /**
253 : : * Check if still connected.
254 : : * @param[out] errmsg The error string, if the socket has been disconnected.
255 : : * @return true if connected
256 : : */
257 : : [[nodiscard]] virtual bool IsConnected(std::string& errmsg) const;
258 : :
259 : : /**
260 : : * Check if the internal socket is equal to `s`. Use only in tests.
261 : : */
262 : : bool operator==(SOCKET s) const;
263 : :
264 : : protected:
265 : : /**
266 : : * Contained socket. `INVALID_SOCKET` designates the object is empty.
267 : : */
268 : : SOCKET m_socket;
269 : :
270 : : private:
271 : : /**
272 : : * Close `m_socket` if it is not `INVALID_SOCKET`.
273 : : */
274 : : void Close();
275 : : };
276 : :
277 : : /** Return readable error string for a network error code */
278 : : std::string NetworkErrorString(int err);
279 : :
280 : : #endif // BITCOIN_UTIL_SOCK_H
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