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1 : : // Copyright (c) 2020-present 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 <span>
15 : : #include <string>
16 : : #include <unordered_map>
17 : :
18 : : /**
19 : : * Maximum time to wait for I/O readiness.
20 : : * It will take up until this time to break off in case of an interruption.
21 : : */
22 : : static constexpr auto MAX_WAIT_FOR_IO = 1s;
23 : :
24 : : /**
25 : : * RAII helper class that manages a socket and closes it automatically when it goes out of scope.
26 : : */
27 : : class Sock
28 : : {
29 : : public:
30 : : Sock() = delete;
31 : :
32 : : /**
33 : : * Take ownership of an existent socket.
34 : : */
35 : : explicit Sock(SOCKET s);
36 : :
37 : : /**
38 : : * Copy constructor, disabled because closing the same socket twice is undesirable.
39 : : */
40 : : Sock(const Sock&) = delete;
41 : :
42 : : /**
43 : : * Move constructor, grab the socket from another object and close ours (if set).
44 : : */
45 : : Sock(Sock&& other);
46 : :
47 : : /**
48 : : * Destructor, close the socket or do nothing if empty.
49 : : */
50 : : virtual ~Sock();
51 : :
52 : : /**
53 : : * Copy assignment operator, disabled because closing the same socket twice is undesirable.
54 : : */
55 : : Sock& operator=(const Sock&) = delete;
56 : :
57 : : /**
58 : : * Move assignment operator, grab the socket from another object and close ours (if set).
59 : : */
60 : : virtual Sock& operator=(Sock&& other);
61 : :
62 : : /**
63 : : * send(2) wrapper. Equivalent to `send(m_socket, data, len, flags);`. Code that uses this
64 : : * wrapper can be unit tested if this method is overridden by a mock Sock implementation.
65 : : */
66 : : [[nodiscard]] virtual ssize_t Send(const void* data, size_t len, int flags) const;
67 : :
68 : : /**
69 : : * recv(2) wrapper. Equivalent to `recv(m_socket, buf, len, flags);`. Code that uses this
70 : : * wrapper can be unit tested if this method is overridden by a mock Sock implementation.
71 : : */
72 : : [[nodiscard]] virtual ssize_t Recv(void* buf, size_t len, int flags) const;
73 : :
74 : : /**
75 : : * connect(2) wrapper. Equivalent to `connect(m_socket, addr, addrlen)`. Code that uses this
76 : : * wrapper can be unit tested if this method is overridden by a mock Sock implementation.
77 : : */
78 : : [[nodiscard]] virtual int Connect(const sockaddr* addr, socklen_t addr_len) const;
79 : :
80 : : /**
81 : : * bind(2) wrapper. Equivalent to `bind(m_socket, addr, addr_len)`. Code that uses this
82 : : * wrapper can be unit tested if this method is overridden by a mock Sock implementation.
83 : : */
84 : : [[nodiscard]] virtual int Bind(const sockaddr* addr, socklen_t addr_len) const;
85 : :
86 : : /**
87 : : * listen(2) wrapper. Equivalent to `listen(m_socket, backlog)`. Code that uses this
88 : : * wrapper can be unit tested if this method is overridden by a mock Sock implementation.
89 : : */
90 : : [[nodiscard]] virtual int Listen(int backlog) const;
91 : :
92 : : /**
93 : : * accept(2) wrapper. Equivalent to `std::make_unique<Sock>(accept(m_socket, addr, addr_len))`.
94 : : * Code that uses this wrapper can be unit tested if this method is overridden by a mock Sock
95 : : * implementation.
96 : : * The returned unique_ptr is empty if `accept()` failed in which case errno will be set.
97 : : */
98 : : [[nodiscard]] virtual std::unique_ptr<Sock> Accept(sockaddr* addr, socklen_t* addr_len) const;
99 : :
100 : : /**
101 : : * getsockopt(2) wrapper. Equivalent to
102 : : * `getsockopt(m_socket, level, opt_name, opt_val, opt_len)`. Code that uses this
103 : : * wrapper can be unit tested if this method is overridden by a mock Sock implementation.
104 : : */
105 : : [[nodiscard]] virtual int GetSockOpt(int level,
106 : : int opt_name,
107 : : void* opt_val,
108 : : socklen_t* opt_len) const;
109 : :
110 : : /**
111 : : * setsockopt(2) wrapper. Equivalent to
112 : : * `setsockopt(m_socket, level, opt_name, opt_val, opt_len)`. Code that uses this
113 : : * wrapper can be unit tested if this method is overridden by a mock Sock implementation.
114 : : */
115 : : [[nodiscard]] virtual int SetSockOpt(int level,
116 : : int opt_name,
117 : : const void* opt_val,
118 : : socklen_t opt_len) const;
119 : :
120 : : /**
121 : : * getsockname(2) wrapper. Equivalent to
122 : : * `getsockname(m_socket, name, name_len)`. Code that uses this
123 : : * wrapper can be unit tested if this method is overridden by a mock Sock implementation.
124 : : */
125 : : [[nodiscard]] virtual int GetSockName(sockaddr* name, socklen_t* name_len) const;
126 : :
127 : : /**
128 : : * Set the non-blocking option on the socket.
129 : : * @return true if set successfully
130 : : */
131 : : [[nodiscard]] virtual bool SetNonBlocking() const;
132 : :
133 : : /**
134 : : * Check if the underlying socket can be used for `select(2)` (or the `Wait()` method).
135 : : * @return true if selectable
136 : : */
137 : : [[nodiscard]] virtual bool IsSelectable() const;
138 : :
139 : : using Event = uint8_t;
140 : :
141 : : /**
142 : : * If passed to `Wait()`, then it will wait for readiness to read from the socket.
143 : : */
144 : : static constexpr Event RECV = 0b001;
145 : :
146 : : /**
147 : : * If passed to `Wait()`, then it will wait for readiness to send to the socket.
148 : : */
149 : : static constexpr Event SEND = 0b010;
150 : :
151 : : /**
152 : : * Ignored if passed to `Wait()`, but could be set in the occurred events if an
153 : : * exceptional condition has occurred on the socket or if it has been disconnected.
154 : : */
155 : : static constexpr Event ERR = 0b100;
156 : :
157 : : /**
158 : : * Wait for readiness for input (recv) or output (send).
159 : : * @param[in] timeout Wait this much for at least one of the requested events to occur.
160 : : * @param[in] requested Wait for those events, bitwise-or of `RECV` and `SEND`.
161 : : * @param[out] occurred If not nullptr and the function returns `true`, then this
162 : : * indicates which of the requested events occurred (`ERR` will be added, even if
163 : : * not requested, if an exceptional event occurs on the socket).
164 : : * A timeout is indicated by return value of `true` and `occurred` being set to 0.
165 : : * @return true on success (or timeout, if `occurred` of 0 is returned), false otherwise
166 : : */
167 : : [[nodiscard]] virtual bool Wait(std::chrono::milliseconds timeout,
168 : : Event requested,
169 : : Event* occurred = nullptr) const;
170 : :
171 : : /**
172 : : * Auxiliary requested/occurred events to wait for in `WaitMany()`.
173 : : */
174 : : struct Events {
175 [ # # ]: 2336176 : explicit Events(Event req) : requested{req} {}
[ + - + - ]
176 : : Event requested;
177 : : Event occurred{0};
178 : : };
179 : :
180 : : struct HashSharedPtrSock {
181 : 2354984 : size_t operator()(const std::shared_ptr<const Sock>& s) const
182 : : {
183 [ + - ]: 2354984 : return s ? s->m_socket : std::numeric_limits<SOCKET>::max();
184 : : }
185 : : };
186 : :
187 : : struct EqualSharedPtrSock {
188 : 2341178 : bool operator()(const std::shared_ptr<const Sock>& lhs,
189 : : const std::shared_ptr<const Sock>& rhs) const
190 : : {
191 [ + - + - ]: 2341178 : if (lhs && rhs) {
192 : 2341178 : return lhs->m_socket == rhs->m_socket;
193 : : }
194 [ # # # # ]: 0 : if (!lhs && !rhs) {
195 : 0 : return true;
196 : : }
197 : : return false;
198 : : }
199 : : };
200 : :
201 : : /**
202 : : * On which socket to wait for what events in `WaitMany()`.
203 : : * The `shared_ptr` is copied into the map to ensure that the `Sock` object
204 : : * is not destroyed (its destructor would close the underlying socket).
205 : : * If this happens shortly before or after we call `poll(2)` and a new
206 : : * socket gets created under the same file descriptor number then the report
207 : : * from `WaitMany()` will be bogus.
208 : : */
209 : : using EventsPerSock = std::unordered_map<std::shared_ptr<const Sock>, Events, HashSharedPtrSock, EqualSharedPtrSock>;
210 : :
211 : : /**
212 : : * Same as `Wait()`, but wait on many sockets within the same timeout.
213 : : * @param[in] timeout Wait this long for at least one of the requested events to occur.
214 : : * @param[in,out] events_per_sock Wait for the requested events on these sockets and set
215 : : * `occurred` for the events that actually occurred.
216 : : * @return true on success (or timeout, if all `what[].occurred` are returned as 0),
217 : : * false otherwise
218 : : */
219 : : [[nodiscard]] virtual bool WaitMany(std::chrono::milliseconds timeout,
220 : : EventsPerSock& events_per_sock) const;
221 : :
222 : : /* Higher level, convenience, methods. These may throw. */
223 : :
224 : : /**
225 : : * Send the given data, retrying on transient errors.
226 : : * @param[in] data Data to send.
227 : : * @param[in] timeout Timeout for the entire operation.
228 : : * @param[in] interrupt If this is signaled then the operation is canceled.
229 : : * @throws std::runtime_error if the operation cannot be completed. In this case only some of
230 : : * the data will be written to the socket.
231 : : */
232 : : virtual void SendComplete(std::span<const unsigned char> data,
233 : : std::chrono::milliseconds timeout,
234 : : CThreadInterrupt& interrupt) const;
235 : :
236 : : /**
237 : : * Convenience method, equivalent to `SendComplete(MakeUCharSpan(data), timeout, interrupt)`.
238 : : */
239 : : virtual void SendComplete(std::span<const char> data,
240 : : std::chrono::milliseconds timeout,
241 : : CThreadInterrupt& interrupt) const;
242 : :
243 : : /**
244 : : * Read from socket until a terminator character is encountered. Will never consume bytes past
245 : : * the terminator from the socket.
246 : : * @param[in] terminator Character up to which to read from the socket.
247 : : * @param[in] timeout Timeout for the entire operation.
248 : : * @param[in] interrupt If this is signaled then the operation is canceled.
249 : : * @param[in] max_data The maximum amount of data (in bytes) to receive. If this many bytes
250 : : * are received and there is still no terminator, then this method will throw an exception.
251 : : * @return The data that has been read, without the terminating character.
252 : : * @throws std::runtime_error if the operation cannot be completed. In this case some bytes may
253 : : * have been consumed from the socket.
254 : : */
255 : : [[nodiscard]] virtual std::string RecvUntilTerminator(uint8_t terminator,
256 : : std::chrono::milliseconds timeout,
257 : : CThreadInterrupt& interrupt,
258 : : size_t max_data) const;
259 : :
260 : : /**
261 : : * Check if still connected.
262 : : * @param[out] errmsg The error string, if the socket has been disconnected.
263 : : * @return true if connected
264 : : */
265 : : [[nodiscard]] virtual bool IsConnected(std::string& errmsg) const;
266 : :
267 : : /**
268 : : * Check if the internal socket is equal to `s`. Use only in tests.
269 : : */
270 : : bool operator==(SOCKET s) const;
271 : :
272 : : protected:
273 : : /**
274 : : * Contained socket. `INVALID_SOCKET` designates the object is empty.
275 : : */
276 : : SOCKET m_socket;
277 : :
278 : : private:
279 : : /**
280 : : * Close `m_socket` if it is not `INVALID_SOCKET`.
281 : : */
282 : : void Close();
283 : : };
284 : :
285 : : /** Return readable error string for a network error code */
286 : : std::string NetworkErrorString(int err);
287 : :
288 : : #endif // BITCOIN_UTIL_SOCK_H
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