Improve BIO_socket_wait(), BIO_wait(), BIO_connect_retry(), and their docs

[openssl.git] / crypto / bio / bio_lib.c

diff --git a/crypto/bio/bio_lib.c b/crypto/bio/bio_lib.c
index 9d63b491e2d24877cf14d5ac0a134d4b7d1ea69c..c3c798d4b4fd18542e8f9c55b7fe8603790d5eca 100644 (file)
--- a/crypto/bio/bio_lib.c
+++ b/crypto/bio/bio_lib.c
@@ -1,5 +1,5 @@
 /*
- * Copyright 1995-2018 The OpenSSL Project Authors. All Rights Reserved.
+ * Copyright 1995-2020 The OpenSSL Project Authors. All Rights Reserved.
  *
  * Licensed under the Apache License 2.0 (the "License").  You may not use
  * this file except in compliance with the License.  You can obtain a copy
@@ -10,7 +10,7 @@
 #include <stdio.h>
 #include <errno.h>
 #include <openssl/crypto.h>
-#include "bio_lcl.h"
+#include "bio_local.h"
 #include "internal/cryptlib.h"
 
 
@@ -750,7 +750,7 @@ int BIO_set_ex_data(BIO *bio, int idx, void *data)
     return CRYPTO_set_ex_data(&(bio->ex_data), idx, data);
 }
 
-void *BIO_get_ex_data(BIO *bio, int idx)
+void *BIO_get_ex_data(const BIO *bio, int idx)
 {
     return CRYPTO_get_ex_data(&(bio->ex_data), idx);
 }
@@ -784,3 +784,120 @@ void bio_cleanup(void)
     CRYPTO_THREAD_lock_free(bio_type_lock);
     bio_type_lock = NULL;
 }
+
+/* Internal variant of the below BIO_wait() not calling BIOerr() */
+static int bio_wait(BIO *bio, time_t max_time, unsigned int nap_milliseconds)
+{
+#ifndef OPENSSL_NO_SOCK
+    int fd;
+#endif
+    long sec_diff;
+
+    if (max_time == 0) /* no timeout */
+        return 1;
+
+#ifndef OPENSSL_NO_SOCK
+    if (BIO_get_fd(bio, &fd) > 0 && fd < FD_SETSIZE)
+        return BIO_socket_wait(fd, BIO_should_read(bio), max_time);
+#endif
+    /* fall back to polling since no sockets are available */
+
+    sec_diff = (long)(max_time - time(NULL)); /* might overflow */
+    if (sec_diff < 0)
+        return 0; /* clearly timeout */
+
+    /* now take a nap at most the given number of milliseconds */
+    if (sec_diff == 0) { /* we are below the 1 seconds resolution of max_time */
+        if (nap_milliseconds > 1000)
+            nap_milliseconds = 1000;
+    } else { /* for sec_diff > 0, take min(sec_diff * 1000, nap_milliseconds) */
+        if ((unsigned long)sec_diff * 1000 < nap_milliseconds)
+            nap_milliseconds = (unsigned int)sec_diff * 1000;
+    }
+    ossl_sleep(nap_milliseconds);
+    return 1;
+}
+
+/*-
+ * Wait on (typically socket-based) BIO at most until max_time.
+ * Succeed immediately if max_time == 0.
+ * If sockets are not available support polling: succeed after waiting at most
+ * the number of nap_milliseconds in order to avoid a tight busy loop.
+ * Call BIOerr(...) on timeout or error.
+ * Returns -1 on error, 0 on timeout, and 1 on success.
+ */
+int BIO_wait(BIO *bio, time_t max_time, unsigned int nap_milliseconds)
+{
+    int rv = bio_wait(bio, max_time, nap_milliseconds);
+
+    if (rv <= 0)
+        BIOerr(0, rv == 0 ? BIO_R_TRANSFER_TIMEOUT : BIO_R_TRANSFER_ERROR);
+    return rv;
+}
+
+/*
+ * Connect via given BIO using BIO_do_connect() until success/timeout/error.
+ * Parameter timeout == 0 means no timeout, < 0 means exactly one try.
+ * For non-blocking and potentially even non-socket BIOs perform polling with
+ * the given density: between polls sleep nap_milliseconds using BIO_wait()
+ * in order to avoid a tight busy loop.
+ * Returns -1 on error, 0 on timeout, and 1 on success.
+ */
+int BIO_do_connect_retry(BIO *bio, int timeout, int nap_milliseconds)
+{
+    int blocking = timeout <= 0;
+    time_t max_time = timeout > 0 ? time(NULL) + timeout : 0;
+    int rv;
+
+    if (bio == NULL) {
+        BIOerr(0, ERR_R_PASSED_NULL_PARAMETER);
+        return -1;
+    }
+
+    if (nap_milliseconds < 0)
+        nap_milliseconds = 100;
+    BIO_set_nbio(bio, !blocking);
+
+ retry:
+    rv = BIO_do_connect(bio); /* This may indirectly call ERR_clear_error(); */
+
+    if (rv <= 0) { /* could be timeout or retryable error or fatal error */
+        int err = ERR_peek_last_error();
+        int reason = ERR_GET_REASON(err);
+        int do_retry = BIO_should_retry(bio); /* may be 1 only if !blocking */
+
+        if (ERR_GET_LIB(err) == ERR_LIB_BIO) {
+            switch (reason) {
+            case ERR_R_SYS_LIB:
+                /*
+                 * likely retryable system error occurred, which may be
+                 * EAGAIN (resource temporarily unavailable) some 40 secs after
+                 * calling getaddrinfo(): Temporary failure in name resolution
+                 * or a premature ETIMEDOUT, some 30 seconds after connect()
+                 */
+            case BIO_R_CONNECT_ERROR:
+            case BIO_R_NBIO_CONNECT_ERROR:
+                /* some likely retryable connection error occurred */
+                (void)BIO_reset(bio); /* often needed to avoid retry failure */
+                do_retry = 1;
+                break;
+            default:
+                break;
+            }
+        }
+        if (timeout >= 0 && do_retry) {
+            ERR_clear_error(); /* using ERR_pop_to_mark() would be cleaner */
+            /* will not actually wait if timeout == 0 (i.e., blocking BIO): */
+            rv = bio_wait(bio, max_time, nap_milliseconds);
+            if (rv > 0)
+                goto retry;
+            BIOerr(0, rv == 0 ? BIO_R_CONNECT_TIMEOUT : BIO_R_CONNECT_ERROR);
+        } else {
+            rv = -1;
+            if (err == 0) /* missing error queue entry */
+                BIOerr(0, BIO_R_CONNECT_ERROR); /* workaround: general error */
+        }
+    }
+
+    return rv;
+}