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1 /*
2  *  TCP/IP or UDP/IP networking functions
3  *
4  *  Copyright The Mbed TLS Contributors
5  *  SPDX-License-Identifier: Apache-2.0
6  *
7  *  Licensed under the Apache License, Version 2.0 (the "License"); you may
8  *  not use this file except in compliance with the License.
9  *  You may obtain a copy of the License at
10  *
11  *  http://www.apache.org/licenses/LICENSE-2.0
12  *
13  *  Unless required by applicable law or agreed to in writing, software
14  *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
15  *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16  *  See the License for the specific language governing permissions and
17  *  limitations under the License.
18  */
19 
20 /* Enable definition of getaddrinfo() even when compiling with -std=c99. Must
21  * be set before mbedtls_config.h, which pulls in glibc's features.h indirectly.
22  * Harmless on other platforms. */
23 #ifndef _POSIX_C_SOURCE
24 #define _POSIX_C_SOURCE 200112L
25 #endif
26 #ifndef _XOPEN_SOURCE
27 #define _XOPEN_SOURCE 600 /* sockaddr_storage */
28 #endif
29 
30 #include "common.h"
31 
32 #if defined(MBEDTLS_NET_C)
33 
34 #if !defined(unix) && !defined(__unix__) && !defined(__unix) && \
35     !defined(__APPLE__) && !defined(_WIN32) && !defined(__QNXNTO__) && \
36     !defined(__HAIKU__) && !defined(__midipix__)
37 #error "This module only works on Unix and Windows, see MBEDTLS_NET_C in mbedtls_config.h"
38 #endif
39 
40 #include "mbedtls/platform.h"
41 
42 #include "mbedtls/net_sockets.h"
43 #include "mbedtls/error.h"
44 
45 #include <string.h>
46 
47 #if (defined(_WIN32) || defined(_WIN32_WCE)) && !defined(EFIX64) && \
48     !defined(EFI32)
49 
50 #define IS_EINTR(ret) ((ret) == WSAEINTR)
51 
52 #if !defined(_WIN32_WINNT)
53 /* Enables getaddrinfo() & Co */
54 #define _WIN32_WINNT 0x0501
55 #endif
56 
57 #include <ws2tcpip.h>
58 
59 #include <winsock2.h>
60 #include <windows.h>
61 #if (_WIN32_WINNT < 0x0501)
62 #include <wspiapi.h>
63 #endif
64 
65 #if defined(_MSC_VER)
66 #if defined(_WIN32_WCE)
67 #pragma comment( lib, "ws2.lib" )
68 #else
69 #pragma comment( lib, "ws2_32.lib" )
70 #endif
71 #endif /* _MSC_VER */
72 
73 #define read(fd, buf, len)        recv(fd, (char *) (buf), (int) (len), 0)
74 #define write(fd, buf, len)       send(fd, (char *) (buf), (int) (len), 0)
75 #define close(fd)               closesocket(fd)
76 
77 static int wsa_init_done = 0;
78 
79 #else /* ( _WIN32 || _WIN32_WCE ) && !EFIX64 && !EFI32 */
80 
81 #include <sys/types.h>
82 #include <sys/socket.h>
83 #include <netinet/in.h>
84 #include <arpa/inet.h>
85 #include <sys/time.h>
86 #include <unistd.h>
87 #include <signal.h>
88 #include <fcntl.h>
89 #include <netdb.h>
90 #include <errno.h>
91 
92 #define IS_EINTR(ret) ((ret) == EINTR)
93 
94 #endif /* ( _WIN32 || _WIN32_WCE ) && !EFIX64 && !EFI32 */
95 
96 /* Some MS functions want int and MSVC warns if we pass size_t,
97  * but the standard functions use socklen_t, so cast only for MSVC */
98 #if defined(_MSC_VER)
99 #define MSVC_INT_CAST   (int)
100 #else
101 #define MSVC_INT_CAST
102 #endif
103 
104 #include <stdio.h>
105 
106 #if defined(MBEDTLS_HAVE_TIME)
107 #include <time.h>
108 #endif
109 
110 #include <stdint.h>
111 
112 #include "socket_compat.h"
113 #ifdef USE_LWIP
114 #include "lwip/sockets.h"
115 #endif
116 
117 /*
118  * Prepare for using the sockets interface
119  */
net_prepare(void)120 static int net_prepare(void)
121 {
122 #if (defined(_WIN32) || defined(_WIN32_WCE)) && !defined(EFIX64) && \
123     !defined(EFI32)
124     WSADATA wsaData;
125 
126     if (wsa_init_done == 0) {
127         if (WSAStartup(MAKEWORD(2, 0), &wsaData) != 0) {
128             return MBEDTLS_ERR_NET_SOCKET_FAILED;
129         }
130 
131         wsa_init_done = 1;
132     }
133 #else
134 #if !defined(EFIX64) && !defined(EFI32)
135     signal(SIGPIPE, SIG_IGN);
136 #endif
137 #endif
138     return 0;
139 }
140 
141 /*
142  * Return 0 if the file descriptor is valid, an error otherwise.
143  * If for_select != 0, check whether the file descriptor is within the range
144  * allowed for fd_set used for the FD_xxx macros and the select() function.
145  */
check_fd(int fd,int for_select)146 static int check_fd(int fd, int for_select)
147 {
148     if (fd < 0) {
149         return MBEDTLS_ERR_NET_INVALID_CONTEXT;
150     }
151 
152 #if (defined(_WIN32) || defined(_WIN32_WCE)) && !defined(EFIX64) && \
153     !defined(EFI32)
154     (void) for_select;
155 #else
156     /* A limitation of select() is that it only works with file descriptors
157      * that are strictly less than FD_SETSIZE. This is a limitation of the
158      * fd_set type. Error out early, because attempting to call FD_SET on a
159      * large file descriptor is a buffer overflow on typical platforms. */
160     if (for_select && fd >= FD_SETSIZE) {
161         return MBEDTLS_ERR_NET_POLL_FAILED;
162     }
163 #endif
164 
165     return 0;
166 }
167 
168 /*
169  * Initialize a context
170  */
mbedtls_net_init(mbedtls_net_context * ctx)171 void mbedtls_net_init(mbedtls_net_context *ctx)
172 {
173     ctx->fd = -1;
174 }
175 
176 /*
177  * Initiate a TCP connection with host:port and the given protocol
178  */
mbedtls_net_connect(mbedtls_net_context * ctx,const char * host,const char * port,int proto)179 int mbedtls_net_connect(mbedtls_net_context *ctx, const char *host,
180                         const char *port, int proto)
181 {
182     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
183     struct addrinfo hints, *addr_list, *cur;
184 
185     if ((ret = net_prepare()) != 0) {
186         return ret;
187     }
188 
189     /* Do name resolution with both IPv6 and IPv4 */
190     memset(&hints, 0, sizeof(hints));
191     hints.ai_family = AF_UNSPEC;
192     hints.ai_socktype = proto == MBEDTLS_NET_PROTO_UDP ? SOCK_DGRAM : SOCK_STREAM;
193     hints.ai_protocol = proto == MBEDTLS_NET_PROTO_UDP ? IPPROTO_UDP : IPPROTO_TCP;
194 
195     if (getaddrinfo(host, port, &hints, &addr_list) != 0) {
196         return MBEDTLS_ERR_NET_UNKNOWN_HOST;
197     }
198 
199     /* Try the sockaddrs until a connection succeeds */
200     ret = MBEDTLS_ERR_NET_UNKNOWN_HOST;
201     for (cur = addr_list; cur != NULL; cur = cur->ai_next) {
202 #ifdef LITEOS_VERSION
203         if (cur->ai_family != AF_INET || cur->ai_socktype != SOCK_STREAM) {
204             continue;
205         }
206         ctx->fd = (int) socket(AF_INET, SOCK_STREAM, 0);
207 #else
208         ctx->fd = (int) socket(cur->ai_family, cur->ai_socktype,
209                                cur->ai_protocol);
210 #endif
211         if(ctx->fd < 0)
212         {
213             ret = MBEDTLS_ERR_NET_SOCKET_FAILED;
214             continue;
215         }
216 
217         if (connect(ctx->fd, cur->ai_addr, MSVC_INT_CAST cur->ai_addrlen) == 0) {
218             ret = 0;
219             break;
220         }
221 
222 #ifdef USE_LWIP
223         lwip_close(ctx->fd);
224 #else
225         close(ctx->fd);
226 #endif
227         ret = MBEDTLS_ERR_NET_CONNECT_FAILED;
228     }
229 
230     freeaddrinfo(addr_list);
231 
232     return ret;
233 }
234 
235 /*
236  * Create a listening socket on bind_ip:port
237  */
mbedtls_net_bind(mbedtls_net_context * ctx,const char * bind_ip,const char * port,int proto)238 int mbedtls_net_bind(mbedtls_net_context *ctx, const char *bind_ip, const char *port, int proto)
239 {
240     int n, ret;
241     struct addrinfo hints, *addr_list, *cur;
242 
243     if ((ret = net_prepare()) != 0) {
244         return ret;
245     }
246 
247     /* Bind to IPv6 and/or IPv4, but only in the desired protocol */
248     memset(&hints, 0, sizeof(hints));
249     hints.ai_family = AF_UNSPEC;
250     hints.ai_socktype = proto == MBEDTLS_NET_PROTO_UDP ? SOCK_DGRAM : SOCK_STREAM;
251     hints.ai_protocol = proto == MBEDTLS_NET_PROTO_UDP ? IPPROTO_UDP : IPPROTO_TCP;
252     if (bind_ip == NULL) {
253         hints.ai_flags = AI_PASSIVE;
254     }
255 
256     if (getaddrinfo(bind_ip, port, &hints, &addr_list) != 0) {
257         return MBEDTLS_ERR_NET_UNKNOWN_HOST;
258     }
259 
260     /* Try the sockaddrs until a binding succeeds */
261     ret = MBEDTLS_ERR_NET_UNKNOWN_HOST;
262     for (cur = addr_list; cur != NULL; cur = cur->ai_next) {
263         ctx->fd = (int) socket(cur->ai_family, cur->ai_socktype,
264                                cur->ai_protocol);
265         if (ctx->fd < 0) {
266             ret = MBEDTLS_ERR_NET_SOCKET_FAILED;
267             continue;
268         }
269 
270         n = 1;
271         if (setsockopt(ctx->fd, SOL_SOCKET, SO_REUSEADDR,
272                        (const char *) &n, sizeof( n )) != 0) {
273 #ifdef USE_LWIP
274             lwip_close(ctx->fd);
275 #else
276             close(ctx->fd);
277 #endif
278             ret = MBEDTLS_ERR_NET_SOCKET_FAILED;
279             continue;
280         }
281 
282         if (bind(ctx->fd, cur->ai_addr, MSVC_INT_CAST cur->ai_addrlen) != 0) {
283 #ifdef USE_LWIP
284             lwip_close(ctx->fd);
285 #else
286             close(ctx->fd);
287 #endif
288             ret = MBEDTLS_ERR_NET_BIND_FAILED;
289             continue;
290         }
291 
292         /* Listen only makes sense for TCP */
293         if (proto == MBEDTLS_NET_PROTO_TCP) {
294             if (listen(ctx->fd, MBEDTLS_NET_LISTEN_BACKLOG) != 0) {
295 #ifdef USE_LWIP
296                 lwip_close(ctx->fd);
297 #else
298                 close(ctx->fd);
299 #endif
300                 ret = MBEDTLS_ERR_NET_LISTEN_FAILED;
301                 continue;
302             }
303         }
304 
305         /* Bind was successful */
306         ret = 0;
307         break;
308     }
309 
310     freeaddrinfo(addr_list);
311 
312     return ret;
313 
314 }
315 
316 #if (defined(_WIN32) || defined(_WIN32_WCE)) && !defined(EFIX64) && \
317     !defined(EFI32)
318 /*
319  * Check if the requested operation would be blocking on a non-blocking socket
320  * and thus 'failed' with a negative return value.
321  */
net_would_block(const mbedtls_net_context * ctx)322 static int net_would_block(const mbedtls_net_context *ctx)
323 {
324     ((void) ctx);
325     return WSAGetLastError() == WSAEWOULDBLOCK;
326 }
327 #else
328 /*
329  * Check if the requested operation would be blocking on a non-blocking socket
330  * and thus 'failed' with a negative return value.
331  *
332  * Note: on a blocking socket this function always returns 0!
333  */
net_would_block(const mbedtls_net_context * ctx)334 static int net_would_block(const mbedtls_net_context *ctx)
335 {
336     int err = errno;
337 
338     /*
339      * Never return 'WOULD BLOCK' on a blocking socket
340      */
341 #ifdef USE_LWIP
342     if ((lwip_fcntl(ctx->fd, F_GETFL, 0) & O_NONBLOCK) != O_NONBLOCK) {
343 #else
344     if ((fcntl(ctx->fd, F_GETFL) & O_NONBLOCK) != O_NONBLOCK) {
345 #endif
346         errno = err;
347         return 0;
348     }
349 
350     switch (errno = err) {
351 #if defined EAGAIN
352         case EAGAIN:
353 #endif
354 #if defined EWOULDBLOCK && EWOULDBLOCK != EAGAIN
355         case EWOULDBLOCK:
356 #endif
357     return 1;
358     }
359     return 0;
360 }
361 #endif /* ( _WIN32 || _WIN32_WCE ) && !EFIX64 && !EFI32 */
362 
363 /*
364  * Accept a connection from a remote client
365  */
366 int mbedtls_net_accept(mbedtls_net_context *bind_ctx,
367                        mbedtls_net_context *client_ctx,
368                        void *client_ip, size_t buf_size, size_t *ip_len)
369 {
370     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
371     int type;
372 
373     struct sockaddr_storage client_addr;
374 
375 #if defined(__socklen_t_defined) || defined(_SOCKLEN_T) ||  \
376     defined(_SOCKLEN_T_DECLARED) || defined(__DEFINED_socklen_t) || \
377     defined(socklen_t) || (defined(_POSIX_VERSION) && _POSIX_VERSION >= 200112L)
378     socklen_t n = (socklen_t) sizeof(client_addr);
379     socklen_t type_len = (socklen_t) sizeof(type);
380 #else
381     int n = (int) sizeof(client_addr);
382     int type_len = (int) sizeof(type);
383 #endif
384 
385     /* Is this a TCP or UDP socket? */
386     if (getsockopt(bind_ctx->fd, SOL_SOCKET, SO_TYPE,
387                    (void *) &type, &type_len) != 0 ||
388         (type != SOCK_STREAM && type != SOCK_DGRAM)) {
389         return MBEDTLS_ERR_NET_ACCEPT_FAILED;
390     }
391 
392     if (type == SOCK_STREAM) {
393         /* TCP: actual accept() */
394         ret = client_ctx->fd = (int) accept(bind_ctx->fd,
395                                             (struct sockaddr *) &client_addr, &n);
396     } else {
397         /* UDP: wait for a message, but keep it in the queue */
398         char buf[1] = { 0 };
399 
400         ret = (int) recvfrom(bind_ctx->fd, buf, sizeof(buf), MSG_PEEK,
401                              (struct sockaddr *) &client_addr, &n);
402 
403 #if defined(_WIN32)
404         if (ret == SOCKET_ERROR &&
405             WSAGetLastError() == WSAEMSGSIZE) {
406             /* We know buf is too small, thanks, just peeking here */
407             ret = 0;
408         }
409 #endif
410     }
411 
412     if (ret < 0) {
413         if (net_would_block(bind_ctx) != 0) {
414             return MBEDTLS_ERR_SSL_WANT_READ;
415         }
416 
417         return MBEDTLS_ERR_NET_ACCEPT_FAILED;
418     }
419 
420     /* UDP: hijack the listening socket to communicate with the client,
421      * then bind a new socket to accept new connections */
422     if (type != SOCK_STREAM) {
423         struct sockaddr_storage local_addr;
424         int one = 1;
425 
426         if (connect(bind_ctx->fd, (struct sockaddr *) &client_addr, n) != 0) {
427             return MBEDTLS_ERR_NET_ACCEPT_FAILED;
428         }
429 
430         client_ctx->fd = bind_ctx->fd;
431         bind_ctx->fd   = -1; /* In case we exit early */
432 
433         n = sizeof(struct sockaddr_storage);
434         if (getsockname(client_ctx->fd,
435                         (struct sockaddr *) &local_addr, &n) != 0 ||
436             (bind_ctx->fd = (int) socket(local_addr.ss_family,
437                                          SOCK_DGRAM, IPPROTO_UDP)) < 0 ||
438             setsockopt(bind_ctx->fd, SOL_SOCKET, SO_REUSEADDR,
439                        (const char *) &one, sizeof(one)) != 0) {
440             return MBEDTLS_ERR_NET_SOCKET_FAILED;
441         }
442 
443         if (bind(bind_ctx->fd, (struct sockaddr *) &local_addr, n) != 0) {
444             return MBEDTLS_ERR_NET_BIND_FAILED;
445         }
446     }
447 
448     if (client_ip != NULL) {
449         if (client_addr.ss_family == AF_INET) {
450             struct sockaddr_in *addr4 = (struct sockaddr_in *) &client_addr;
451             *ip_len = sizeof(addr4->sin_addr.s_addr);
452 
453             if (buf_size < *ip_len) {
454                 return MBEDTLS_ERR_NET_BUFFER_TOO_SMALL;
455             }
456 
457             memcpy(client_ip, &addr4->sin_addr.s_addr, *ip_len);
458         } else {
459             struct sockaddr_in6 *addr6 = (struct sockaddr_in6 *) &client_addr;
460             *ip_len = sizeof(addr6->sin6_addr.s6_addr);
461 
462             if (buf_size < *ip_len) {
463                 return MBEDTLS_ERR_NET_BUFFER_TOO_SMALL;
464             }
465 
466             memcpy(client_ip, &addr6->sin6_addr.s6_addr, *ip_len);
467         }
468     }
469 
470     return 0;
471 }
472 
473 /*
474  * Set the socket blocking or non-blocking
475  */
476 int mbedtls_net_set_block(mbedtls_net_context *ctx)
477 {
478 #if (defined(_WIN32) || defined(_WIN32_WCE)) && !defined(EFIX64) && \
479     !defined(EFI32)
480     u_long n = 0;
481     return ioctlsocket(ctx->fd, FIONBIO, &n);
482 #else
483 #ifdef USE_LWIP
484     return lwip_fcntl(ctx->fd, F_SETFL, lwip_fcntl(ctx->fd, F_GETFL, 0) & ~O_NONBLOCK);
485 #else
486     return fcntl(ctx->fd, F_SETFL, fcntl(ctx->fd, F_GETFL) & ~O_NONBLOCK);
487 #endif // USE_LWIP
488 #endif
489 }
490 
491 int mbedtls_net_set_nonblock(mbedtls_net_context *ctx)
492 {
493 #if (defined(_WIN32) || defined(_WIN32_WCE)) && !defined(EFIX64) && \
494     !defined(EFI32)
495     u_long n = 1;
496     return ioctlsocket(ctx->fd, FIONBIO, &n);
497 #else
498 #ifdef USE_LWIP
499     return lwip_fcntl(ctx->fd, F_SETFL, lwip_fcntl(ctx->fd, F_GETFL, 0) | O_NONBLOCK);
500 #else
501     return fcntl(ctx->fd, F_SETFL, fcntl(ctx->fd, F_GETFL) | O_NONBLOCK);
502 #endif // USE_LWIP
503 #endif
504 }
505 
506 /*
507  * Check if data is available on the socket
508  */
509 
510 int mbedtls_net_poll(mbedtls_net_context *ctx, uint32_t rw, uint32_t timeout)
511 {
512     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
513     struct timeval tv;
514 
515     fd_set read_fds;
516     fd_set write_fds;
517 
518     int fd = ctx->fd;
519 
520     ret = check_fd(fd, 1);
521     if (ret != 0) {
522         return ret;
523     }
524 
525 #if defined(__has_feature)
526 #if __has_feature(memory_sanitizer)
527     /* Ensure that memory sanitizers consider read_fds and write_fds as
528      * initialized even on platforms such as Glibc/x86_64 where FD_ZERO
529      * is implemented in assembly. */
530     memset(&read_fds, 0, sizeof(read_fds));
531     memset(&write_fds, 0, sizeof(write_fds));
532 #endif
533 #endif
534 
535     FD_ZERO(&read_fds);
536     if (rw & MBEDTLS_NET_POLL_READ) {
537         rw &= ~MBEDTLS_NET_POLL_READ;
538         FD_SET(fd, &read_fds);
539     }
540 
541     FD_ZERO(&write_fds);
542     if (rw & MBEDTLS_NET_POLL_WRITE) {
543         rw &= ~MBEDTLS_NET_POLL_WRITE;
544         FD_SET(fd, &write_fds);
545     }
546 
547     if (rw != 0) {
548         return MBEDTLS_ERR_NET_BAD_INPUT_DATA;
549     }
550 
551     tv.tv_sec  = timeout / 1000;
552     tv.tv_usec = (timeout % 1000) * 1000;
553 
554     do {
555         ret = select(fd + 1, &read_fds, &write_fds, NULL,
556                      timeout == (uint32_t) -1 ? NULL : &tv);
557     } while (IS_EINTR(ret));
558 
559     if (ret < 0) {
560         return MBEDTLS_ERR_NET_POLL_FAILED;
561     }
562 
563     ret = 0;
564     if (FD_ISSET(fd, &read_fds)) {
565         ret |= MBEDTLS_NET_POLL_READ;
566     }
567     if (FD_ISSET(fd, &write_fds)) {
568         ret |= MBEDTLS_NET_POLL_WRITE;
569     }
570 
571     return ret;
572 }
573 
574 /*
575  * Portable usleep helper
576  */
577 void mbedtls_net_usleep(unsigned long usec)
578 {
579 #if defined(_WIN32)
580     Sleep((usec + 999) / 1000);
581 #else
582     struct timeval tv;
583     tv.tv_sec  = usec / 1000000;
584 #if defined(__unix__) || defined(__unix) || \
585     (defined(__APPLE__) && defined(__MACH__))
586     tv.tv_usec = (suseconds_t) usec % 1000000;
587 #else
588     tv.tv_usec = usec % 1000000;
589 #endif
590     select(0, NULL, NULL, NULL, &tv);
591 #endif
592 }
593 
594 /*
595  * Read at most 'len' characters
596  */
597 int mbedtls_net_recv(void *ctx, unsigned char *buf, size_t len)
598 {
599     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
600     int fd = ((mbedtls_net_context *) ctx)->fd;
601 
602     ret = check_fd(fd, 0);
603     if (ret != 0) {
604         return ret;
605     }
606 #ifdef LITEOS_VERSION
607     ret = (int) recv( fd, buf, len, 0);
608 #else
609 
610     ret = (int) read(fd, buf, len);
611 #endif
612 
613     if (ret < 0) {
614         if (net_would_block(ctx) != 0) {
615             return MBEDTLS_ERR_SSL_WANT_READ;
616         }
617 
618 #if (defined(_WIN32) || defined(_WIN32_WCE)) && !defined(EFIX64) && \
619         !defined(EFI32)
620         if (WSAGetLastError() == WSAECONNRESET) {
621             return MBEDTLS_ERR_NET_CONN_RESET;
622         }
623 #else
624         if (errno == EPIPE || errno == ECONNRESET) {
625             return MBEDTLS_ERR_NET_CONN_RESET;
626         }
627 
628         if (errno == EINTR) {
629             return MBEDTLS_ERR_SSL_WANT_READ;
630         }
631 #endif
632 
633         return MBEDTLS_ERR_NET_RECV_FAILED;
634     }
635 
636     return ret;
637 }
638 
639 /*
640  * Read at most 'len' characters, blocking for at most 'timeout' ms
641  */
642 int mbedtls_net_recv_timeout(void *ctx, unsigned char *buf,
643                              size_t len, uint32_t timeout)
644 {
645     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
646     struct timeval tv;
647     fd_set read_fds;
648     int fd = ((mbedtls_net_context *) ctx)->fd;
649 
650     ret = check_fd(fd, 1);
651     if (ret != 0) {
652         return ret;
653     }
654 
655     FD_ZERO(&read_fds);
656     FD_SET(fd, &read_fds);
657 
658     tv.tv_sec  = timeout / 1000;
659     tv.tv_usec = (timeout % 1000) * 1000;
660 
661     ret = select(fd + 1, &read_fds, NULL, NULL, timeout == 0 ? NULL : &tv);
662 
663     /* Zero fds ready means we timed out */
664     if (ret == 0) {
665         return MBEDTLS_ERR_SSL_TIMEOUT;
666     }
667 
668     if (ret < 0) {
669 #if (defined(_WIN32) || defined(_WIN32_WCE)) && !defined(EFIX64) && \
670         !defined(EFI32)
671         if (WSAGetLastError() == WSAEINTR) {
672             return MBEDTLS_ERR_SSL_WANT_READ;
673         }
674 #else
675         if (errno == EINTR) {
676             return MBEDTLS_ERR_SSL_WANT_READ;
677         }
678 #endif
679 
680         return MBEDTLS_ERR_NET_RECV_FAILED;
681     }
682 
683     /* This call will not block */
684     return mbedtls_net_recv(ctx, buf, len);
685 }
686 
687 /*
688  * Write at most 'len' characters
689  */
690 int mbedtls_net_send(void *ctx, const unsigned char *buf, size_t len)
691 {
692     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
693     int fd = ((mbedtls_net_context *) ctx)->fd;
694 
695     ret = check_fd(fd, 0);
696     if (ret != 0) {
697         return ret;
698     }
699 
700 #ifdef LITEOS_VERSION
701     ret = (int) send(fd, buf, len, 0);
702 #else
703 
704     ret = (int) write(fd, buf, len);
705 #endif
706 
707     if (ret < 0) {
708         if (net_would_block(ctx) != 0) {
709             return MBEDTLS_ERR_SSL_WANT_WRITE;
710         }
711 
712 #if (defined(_WIN32) || defined(_WIN32_WCE)) && !defined(EFIX64) && \
713         !defined(EFI32)
714         if (WSAGetLastError() == WSAECONNRESET) {
715             return MBEDTLS_ERR_NET_CONN_RESET;
716         }
717 #else
718         if (errno == EPIPE || errno == ECONNRESET) {
719             return MBEDTLS_ERR_NET_CONN_RESET;
720         }
721 
722         if (errno == EINTR) {
723             return MBEDTLS_ERR_SSL_WANT_WRITE;
724         }
725 #endif
726 
727         return MBEDTLS_ERR_NET_SEND_FAILED;
728     }
729 
730     return ret;
731 }
732 
733 /*
734  * Close the connection
735  */
736 void mbedtls_net_close(mbedtls_net_context *ctx)
737 {
738     if (ctx->fd == -1) {
739         return;
740     }
741 #ifdef USE_LWIP
742     lwip_close(ctx->fd);
743 #else
744     close(ctx->fd);
745 #endif
746 
747     ctx->fd = -1;
748 }
749 
750 /*
751  * Gracefully close the connection
752  */
753 void mbedtls_net_free(mbedtls_net_context *ctx)
754 {
755     if (ctx->fd == -1) {
756         return;
757     }
758 #ifdef USE_LWIP
759     lwip_shutdown(ctx->fd, 2);
760     lwip_close(ctx->fd);
761 #else
762     shutdown(ctx->fd, 2);
763     close(ctx->fd);
764 #endif
765 
766     ctx->fd = -1;
767 }
768 
769 #endif /* MBEDTLS_NET_C */
770