tls: Hide backend implementation details from users

TLS is currently implemented over either OpenSSL or GnuTLS, with more
backends likely to appear in the future. Currently, those backend libraries
are part of the protocol names used during e.g. the configure stage of a
build. Hide those details behind a generically-named declaration for the
TLS protocol to avoid leaking those details into the configuration stage.

configure

@@ -2468,12 +2468,8 @@ sctp_protocol_deps="struct_sctp_event_subscribe"
 sctp_protocol_select="network"
 srtp_protocol_select="rtp_protocol srtp"
 tcp_protocol_select="network"
-tls_gnutls_protocol_deps="gnutls"
-tls_gnutls_protocol_select="tcp_protocol"
-tls_openssl_protocol_conflict="tls_gnutls_protocol"
-tls_openssl_protocol_deps="openssl"
-tls_openssl_protocol_select="tcp_protocol"
-tls_protocol_deps_any="tls_gnutls_protocol tls_openssl_protocol"
+tls_protocol_deps_any="gnutls openssl"
+tls_protocol_select="tcp_protocol"
 udp_protocol_select="network"
 unix_protocol_deps="sys_un_h"
 unix_protocol_select="network"

libavformat/Makefile

@@ -408,8 +408,9 @@ OBJS-$(CONFIG_RTP_PROTOCOL)              += rtpproto.o
 OBJS-$(CONFIG_SCTP_PROTOCOL)             += sctp.o
 OBJS-$(CONFIG_SRTP_PROTOCOL)             += srtpproto.o srtp.o
 OBJS-$(CONFIG_TCP_PROTOCOL)              += tcp.o
-OBJS-$(CONFIG_TLS_GNUTLS_PROTOCOL)       += tls_gnutls.o tls.o
-OBJS-$(CONFIG_TLS_OPENSSL_PROTOCOL)      += tls_openssl.o tls.o
+TLS-OBJS-$(CONFIG_GNUTLS)                += tls_gnutls.o
+TLS-OBJS-$(CONFIG_OPENSSL)               += tls_openssl.o
+OBJS-$(CONFIG_TLS_PROTOCOL)              += tls.o $(TLS-OBJS-yes)
 OBJS-$(CONFIG_UDP_PROTOCOL)              += udp.o
 OBJS-$(CONFIG_UNIX_PROTOCOL)             += unix.o
 

libavformat/network.c

@@ -27,22 +27,26 @@
 
 void ff_tls_init(void)
 {
-#if CONFIG_TLS_OPENSSL_PROTOCOL
+#if CONFIG_TLS_PROTOCOL
+#if CONFIG_OPENSSL
     ff_openssl_init();
 #endif
-#if CONFIG_TLS_GNUTLS_PROTOCOL
+#if CONFIG_GNUTLS
     ff_gnutls_init();
 #endif
+#endif
 }
 
 void ff_tls_deinit(void)
 {
-#if CONFIG_TLS_OPENSSL_PROTOCOL
+#if CONFIG_TLS_PROTOCOL
+#if CONFIG_OPENSSL
     ff_openssl_deinit();
 #endif
-#if CONFIG_TLS_GNUTLS_PROTOCOL
+#if CONFIG_GNUTLS
     ff_gnutls_deinit();
 #endif
+#endif
 }
 
 int ff_network_inited_globally;

libavformat/protocols.c

@@ -48,8 +48,7 @@ extern const URLProtocol ff_rtp_protocol;
 extern const URLProtocol ff_sctp_protocol;
 extern const URLProtocol ff_srtp_protocol;
 extern const URLProtocol ff_tcp_protocol;
-extern const URLProtocol ff_tls_gnutls_protocol;
-extern const URLProtocol ff_tls_openssl_protocol;
+extern const URLProtocol ff_tls_protocol;
 extern const URLProtocol ff_udp_protocol;
 extern const URLProtocol ff_unix_protocol;
 extern const URLProtocol ff_librtmp_protocol;

libavformat/tls.h

@@ -26,8 +26,6 @@
 #include "url.h"
 #include "libavutil/opt.h"
 
-#define CONFIG_TLS_PROTOCOL (CONFIG_TLS_GNUTLS_PROTOCOL | CONFIG_TLS_OPENSSL_PROTOCOL)
-
 typedef struct TLSShared {
     char *ca_file;
     int verify;

libavformat/tls_gnutls.c

@@ -233,7 +233,7 @@ static const AVClass tls_class = {
     .version    = LIBAVUTIL_VERSION_INT,
 };
 
-const URLProtocol ff_tls_gnutls_protocol = {
+const URLProtocol ff_tls_protocol = {
     .name           = "tls",
     .url_open2      = tls_open,
     .url_read       = tls_read,

libavformat/tls_openssl.c

@@ -323,7 +323,7 @@ static const AVClass tls_class = {
     .version    = LIBAVUTIL_VERSION_INT,
 };
 
-const URLProtocol ff_tls_openssl_protocol = {
+const URLProtocol ff_tls_protocol = {
     .name           = "tls",
     .url_open2      = tls_open,
     .url_read       = tls_read,