Test SSL_select_next_proto and SSL_get_fd.

Free code coverage. Also rename things in SSL_select_next_proto so it
works for NPN and ALPN. (I found some code which uses it for ALPN.)

Change-Id: I8d06b768f9484dc3eda1a20506ec84ec3ddbc883
Reviewed-on: https://boringssl-review.googlesource.com/17206
Commit-Queue: Steven Valdez <svaldez@google.com>
Reviewed-by: Steven Valdez <svaldez@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>
diff --git a/ssl/ssl_test.cc b/ssl/ssl_test.cc
index 2bf6eeb..b53c93a 100644
--- a/ssl/ssl_test.cc
+++ b/ssl/ssl_test.cc
@@ -1497,6 +1497,7 @@
 }
 
 static void ExpectFDs(const SSL *ssl, int rfd, int wfd) {
+  EXPECT_EQ(rfd, SSL_get_fd(ssl));
   EXPECT_EQ(rfd, SSL_get_rfd(ssl));
   EXPECT_EQ(wfd, SSL_get_wfd(ssl));
 
@@ -3454,6 +3455,49 @@
   EXPECT_EQ(SSL_R_NO_SUPPORTED_VERSIONS_ENABLED, ERR_GET_REASON(err));
 }
 
+TEST(SSLTest, SelectNextProto) {
+  uint8_t *result;
+  uint8_t result_len;
+
+  // If there is an overlap, it should be returned.
+  EXPECT_EQ(OPENSSL_NPN_NEGOTIATED,
+            SSL_select_next_proto(&result, &result_len,
+                                  (const uint8_t *)"\1a\2bb\3ccc", 9,
+                                  (const uint8_t *)"\1x\1y\1a\1z", 8));
+  EXPECT_EQ(Bytes("a"), Bytes(result, result_len));
+
+  EXPECT_EQ(OPENSSL_NPN_NEGOTIATED,
+            SSL_select_next_proto(&result, &result_len,
+                                  (const uint8_t *)"\1a\2bb\3ccc", 9,
+                                  (const uint8_t *)"\1x\1y\2bb\1z", 9));
+  EXPECT_EQ(Bytes("bb"), Bytes(result, result_len));
+
+  EXPECT_EQ(OPENSSL_NPN_NEGOTIATED,
+            SSL_select_next_proto(&result, &result_len,
+                                  (const uint8_t *)"\1a\2bb\3ccc", 9,
+                                  (const uint8_t *)"\1x\1y\3ccc\1z", 10));
+  EXPECT_EQ(Bytes("ccc"), Bytes(result, result_len));
+
+  // Peer preference order takes precedence over local.
+  EXPECT_EQ(OPENSSL_NPN_NEGOTIATED,
+            SSL_select_next_proto(&result, &result_len,
+                                  (const uint8_t *)"\1a\2bb\3ccc", 9,
+                                  (const uint8_t *)"\3ccc\2bb\1a", 9));
+  EXPECT_EQ(Bytes("a"), Bytes(result, result_len));
+
+  // If there is no overlap, return the first local protocol.
+  EXPECT_EQ(OPENSSL_NPN_NO_OVERLAP,
+            SSL_select_next_proto(&result, &result_len,
+                                  (const uint8_t *)"\1a\2bb\3ccc", 9,
+                                  (const uint8_t *)"\1x\2yy\3zzz", 9));
+  EXPECT_EQ(Bytes("x"), Bytes(result, result_len));
+
+  EXPECT_EQ(OPENSSL_NPN_NO_OVERLAP,
+            SSL_select_next_proto(&result, &result_len, nullptr, 0,
+                                  (const uint8_t *)"\1x\2yy\3zzz", 9));
+  EXPECT_EQ(Bytes("x"), Bytes(result, result_len));
+}
+
 // TODO(davidben): Convert this file to GTest properly.
 TEST(SSLTest, AllTests) {
   if (!TestSSL_SESSIONEncoding(kOpenSSLSession) ||