Add a DTLS test for dropped records

Drop a record from a handshake and check that we can still complete the
handshake. Repeat for all records in the handshake.

Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/6170)

3 files changed, 205 insertions, 7 deletions

diff --git a/test/dtlstest.c b/test/dtlstest.c
index 16d4e0f..859ec6b 100644
--- a/test/dtlstest.c
+++ b/test/dtlstest.c
@@ -46,7 +46,7 @@ static unsigned int timer_cb(SSL *s, unsigned int timer_us)
     ++timer_cb_count;
 
     if (timer_us == 0)
-        return 1000000;
+        return 50000;
     else
         return 2 * timer_us;
 }
@@ -114,6 +114,123 @@ static int test_dtls_unprocessed(int testidx)
     return testresult;
 }
 
+#define CLI_TO_SRV_EPOCH_0_RECS 3
+#define CLI_TO_SRV_EPOCH_1_RECS 1
+#define SRV_TO_CLI_EPOCH_0_RECS 12
+#define SRV_TO_CLI_EPOCH_1_RECS 1
+#define TOTAL_FULL_HAND_RECORDS \
+            (CLI_TO_SRV_EPOCH_0_RECS + CLI_TO_SRV_EPOCH_1_RECS + \
+             SRV_TO_CLI_EPOCH_0_RECS + SRV_TO_CLI_EPOCH_1_RECS)
+
+#define CLI_TO_SRV_RESUME_EPOCH_0_RECS 3
+#define CLI_TO_SRV_RESUME_EPOCH_1_RECS 1
+#define SRV_TO_CLI_RESUME_EPOCH_0_RECS 2
+#define SRV_TO_CLI_RESUME_EPOCH_1_RECS 1
+#define TOTAL_RESUME_HAND_RECORDS \
+            (CLI_TO_SRV_RESUME_EPOCH_0_RECS + CLI_TO_SRV_RESUME_EPOCH_1_RECS + \
+             SRV_TO_CLI_RESUME_EPOCH_0_RECS + SRV_TO_CLI_RESUME_EPOCH_1_RECS)
+
+#define TOTAL_RECORDS (TOTAL_FULL_HAND_RECORDS + TOTAL_RESUME_HAND_RECORDS)
+
+static int test_dtls_drop_records(int idx)
+{
+    SSL_CTX *sctx = NULL, *cctx = NULL;
+    SSL *serverssl = NULL, *clientssl = NULL;
+    BIO *c_to_s_fbio, *mempackbio;
+    int testresult = 0;
+    int epoch = 0;
+    SSL_SESSION *sess = NULL;
+    int cli_to_srv_epoch0, cli_to_srv_epoch1, srv_to_cli_epoch0;
+
+    if (!TEST_true(create_ssl_ctx_pair(DTLS_server_method(),
+                                       DTLS_client_method(),
+                                       DTLS1_VERSION, DTLS_MAX_VERSION,
+                                       &sctx, &cctx, cert, privkey)))
+        return 0;
+
+    if (idx >= TOTAL_FULL_HAND_RECORDS) {
+        /* We're going to do a resumption handshake. Get a session first. */
+        if (!TEST_true(create_ssl_objects(sctx, cctx, &serverssl, &clientssl,
+                                          NULL, NULL))
+                || !TEST_true(create_ssl_connection(serverssl, clientssl,
+                              SSL_ERROR_NONE))
+                || !TEST_ptr(sess = SSL_get1_session(clientssl)))
+            goto end;
+
+        SSL_shutdown(clientssl);
+        SSL_shutdown(serverssl);
+        SSL_free(serverssl);
+        SSL_free(clientssl);
+        serverssl = clientssl = NULL;
+
+        cli_to_srv_epoch0 = CLI_TO_SRV_RESUME_EPOCH_0_RECS;
+        cli_to_srv_epoch1 = CLI_TO_SRV_RESUME_EPOCH_1_RECS;
+        srv_to_cli_epoch0 = SRV_TO_CLI_RESUME_EPOCH_0_RECS;
+        idx -= TOTAL_FULL_HAND_RECORDS;
+    } else {
+        cli_to_srv_epoch0 = CLI_TO_SRV_EPOCH_0_RECS;
+        cli_to_srv_epoch1 = CLI_TO_SRV_EPOCH_1_RECS;
+        srv_to_cli_epoch0 = SRV_TO_CLI_EPOCH_0_RECS;
+    }
+
+    c_to_s_fbio = BIO_new(bio_f_tls_dump_filter());
+    if (!TEST_ptr(c_to_s_fbio))
+        goto end;
+
+    /* BIO is freed by create_ssl_connection on error */
+    if (!TEST_true(create_ssl_objects(sctx, cctx, &serverssl, &clientssl,
+                                      NULL, c_to_s_fbio)))
+        goto end;
+
+    if (sess != NULL) {
+        if (!TEST_true(SSL_set_session(clientssl, sess)))
+            goto end;
+    }
+
+    DTLS_set_timer_cb(clientssl, timer_cb);
+    DTLS_set_timer_cb(serverssl, timer_cb);
+
+    /* Work out which record to drop based on the test number */
+    if (idx >= cli_to_srv_epoch0 + cli_to_srv_epoch1) {
+        mempackbio = SSL_get_wbio(serverssl);
+        idx -= cli_to_srv_epoch0 + cli_to_srv_epoch1;
+        if (idx >= srv_to_cli_epoch0) {
+            epoch = 1;
+            idx -= srv_to_cli_epoch0;
+        }
+    } else {
+        mempackbio = SSL_get_wbio(clientssl);
+        if (idx >= cli_to_srv_epoch0) {
+            epoch = 1;
+            idx -= cli_to_srv_epoch0;
+        }
+         mempackbio = BIO_next(mempackbio);
+    }
+    BIO_ctrl(mempackbio, MEMPACKET_CTRL_SET_DROP_EPOCH, epoch, NULL);
+    BIO_ctrl(mempackbio, MEMPACKET_CTRL_SET_DROP_REC, idx, NULL);
+
+    if (!TEST_true(create_ssl_connection(serverssl, clientssl, SSL_ERROR_NONE)))
+        goto end;
+
+    if (sess != NULL && !TEST_true(SSL_session_reused(clientssl)))
+        goto end;
+
+    /* If the test did what we planned then it should have dropped a record */
+    if (!TEST_int_eq((int)BIO_ctrl(mempackbio, MEMPACKET_CTRL_GET_DROP_REC, 0,
+                                   NULL), -1))
+        goto end;
+
+    testresult = 1;
+ end:
+    SSL_SESSION_free(sess);
+    SSL_free(serverssl);
+    SSL_free(clientssl);
+    SSL_CTX_free(sctx);
+    SSL_CTX_free(cctx);
+
+    return testresult;
+}
+
 int setup_tests(void)
 {
     if (!TEST_ptr(cert = test_get_argument(0))
@@ -121,6 +238,8 @@ int setup_tests(void)
         return 0;
 
     ADD_ALL_TESTS(test_dtls_unprocessed, NUM_TESTS);
+    ADD_ALL_TESTS(test_dtls_drop_records, TOTAL_RECORDS);
+
     return 1;
 }
 
diff --git a/test/ssltestlib.c b/test/ssltestlib.c
index 959e329..041ae26 100644
--- a/test/ssltestlib.c
+++ b/test/ssltestlib.c
@@ -12,6 +12,34 @@
 #include "internal/nelem.h"
 #include "ssltestlib.h"
 #include "testutil.h"
+#include "e_os.h"
+
+#ifdef OPENSSL_SYS_UNIX
+# include <unistd.h>
+
+static ossl_inline void ossl_sleep(unsigned int millis) {
+    usleep(millis * 1000);
+}
+#elif defined(_WIN32)
+# include <windows.h>
+
+static ossl_inline void ossl_sleep(unsigned int millis) {
+    Sleep(millis);
+}
+#else
+/* Fallback to a busy wait */
+static ossl_inline void ossl_sleep(unsigned int millis) {
+    struct timeval start, now;
+    unsigned int elapsedms;
+
+    gettimeofday(&start, NULL);
+    do {
+        gettimeofday(&now, NULL);
+        elapsedms = (((now.tv_sec - start.tv_sec) * 1000000)
+                     + now.tv_usec - start.tv_usec) / 1000;
+    } while (elapsedms < millis);
+}
+#endif
 
 static int tls_dump_new(BIO *bi);
 static int tls_dump_free(BIO *a);
@@ -252,7 +280,10 @@ typedef struct mempacket_test_ctx_st {
     unsigned int currrec;
     unsigned int currpkt;
     unsigned int lastpkt;
+    unsigned int injected;
     unsigned int noinject;
+    unsigned int dropepoch;
+    int droprec;
 } MEMPACKET_TEST_CTX;
 
 static int mempacket_test_new(BIO *bi);
@@ -295,6 +326,8 @@ static int mempacket_test_new(BIO *bio)
         OPENSSL_free(ctx);
         return 0;
     }
+    ctx->dropepoch = 0;
+    ctx->droprec = -1;
     BIO_set_init(bio, 1);
     BIO_set_data(bio, ctx);
     return 1;
@@ -312,8 +345,8 @@ static int mempacket_test_free(BIO *bio)
 }
 
 /* Record Header values */
-#define EPOCH_HI        4
-#define EPOCH_LO        5
+#define EPOCH_HI        3
+#define EPOCH_LO        4
 #define RECORD_SEQUENCE 10
 #define RECORD_LEN_HI   11
 #define RECORD_LEN_LO   12
@@ -341,15 +374,15 @@ static int mempacket_test_read(BIO *bio, char *out, int outl)
     if (outl > thispkt->len)
         outl = thispkt->len;
 
-    if (thispkt->type != INJECT_PACKET_IGNORE_REC_SEQ) {
+    if (thispkt->type != INJECT_PACKET_IGNORE_REC_SEQ
+            && (ctx->injected || ctx->droprec >= 0)) {
         /*
          * Overwrite the record sequence number. We strictly number them in
          * the order received. Since we are actually a reliable transport
          * we know that there won't be any re-ordering. We overwrite to deal
          * with any packets that have been injected
          */
-        for (rem = thispkt->len, rec = thispkt->data
-                ; rem > 0; rec += len, rem -= len) {
+        for (rem = thispkt->len, rec = thispkt->data; rem > 0; rem -= len) {
             if (rem < DTLS1_RT_HEADER_LENGTH)
                 return -1;
             epoch = (rec[EPOCH_HI] << 8) | rec[EPOCH_LO];
@@ -364,10 +397,23 @@ static int mempacket_test_read(BIO *bio, char *out, int outl)
                 seq >>= 8;
                 offset++;
             } while (seq > 0);
-            ctx->currrec++;
 
             len = ((rec[RECORD_LEN_HI] << 8) | rec[RECORD_LEN_LO])
                   + DTLS1_RT_HEADER_LENGTH;
+            if (rem < (int)len)
+                return -1;
+            if (ctx->droprec == (int)ctx->currrec && ctx->dropepoch == epoch) {
+                if (rem > (int)len)
+                    memmove(rec, rec + len, rem - len);
+                outl -= len;
+                ctx->droprec = -1;
+                if (outl == 0)
+                    BIO_set_retry_read(bio);
+            } else {
+                rec += len;
+            }
+
+            ctx->currrec++;
         }
     }
 
@@ -390,6 +436,7 @@ int mempacket_test_inject(BIO *bio, const char *in, int inl, int pktnum,
     if (pktnum >= 0) {
         if (ctx->noinject)
             return -1;
+        ctx->injected  = 1;
     } else {
         ctx->noinject = 1;
     }
@@ -488,6 +535,15 @@ static long mempacket_test_ctrl(BIO *bio, int cmd, long num, void *ptr)
     case BIO_CTRL_FLUSH:
         ret = 1;
         break;
+    case MEMPACKET_CTRL_SET_DROP_EPOCH:
+        ctx->dropepoch = (unsigned int)num;
+        break;
+    case MEMPACKET_CTRL_SET_DROP_REC:
+        ctx->droprec = (int)num;
+        break;
+    case MEMPACKET_CTRL_GET_DROP_REC:
+        ret = ctx->droprec;
+        break;
     case BIO_CTRL_RESET:
     case BIO_CTRL_DUP:
     case BIO_CTRL_PUSH:
@@ -627,6 +683,7 @@ int create_ssl_connection(SSL *serverssl, SSL *clientssl, int want)
     int clienterr = 0, servererr = 0;
     unsigned char buf;
     size_t readbytes;
+    int isdtls = SSL_is_dtls(serverssl);
 
     do {
         err = SSL_ERROR_WANT_WRITE;
@@ -658,10 +715,24 @@ int create_ssl_connection(SSL *serverssl, SSL *clientssl, int want)
             return 0;
         if (clienterr && servererr)
             return 0;
+        if (isdtls) {
+            if (rets > 0 && retc <= 0)
+                DTLSv1_handle_timeout(serverssl);
+            if (retc > 0 && rets <= 0)
+                DTLSv1_handle_timeout(clientssl);
+        }
         if (++abortctr == MAXLOOPS) {
             TEST_info("No progress made");
             return 0;
         }
+        if (isdtls && abortctr <= 50 && (abortctr % 10) == 0) {
+            /*
+             * It looks like we're just spinning. Pause for a short period to
+             * give the DTLS timer a chance to do something. We only do this for
+             * the first few times to prevent hangs.
+             */
+            ossl_sleep(50);
+        }
     } while (retc <=0 || rets <= 0);
 
     /*
diff --git a/test/ssltestlib.h b/test/ssltestlib.h
index 353699d..c96dff5 100644
--- a/test/ssltestlib.h
+++ b/test/ssltestlib.h
@@ -32,6 +32,14 @@ void bio_s_mempacket_test_free(void);
 #define INJECT_PACKET                   1
 #define INJECT_PACKET_IGNORE_REC_SEQ    2
 
+/*
+ * Mempacket BIO ctrls. We make them large enough to not clash with standard BIO
+ * ctrl codes.
+ */
+#define MEMPACKET_CTRL_SET_DROP_EPOCH  (1 << 15)
+#define MEMPACKET_CTRL_SET_DROP_REC    (2 << 15)
+#define MEMPACKET_CTRL_GET_DROP_REC    (3 << 15)
+
 int mempacket_test_inject(BIO *bio, const char *in, int inl, int pktnum,
                           int type);