stream: provide generic registration API

Update the new stream registration API to be `git_stream_register`
which takes a registration structure and a TLS boolean.  This allows
callers to register non-TLS streams as well as TLS streams.

Provide `git_stream_register_tls` that takes just the init callback for
backward compatibliity.

Author: ethomson

include/git2/sys/stream.h

@@ -45,9 +45,9 @@ typedef struct {
 	int version;
 
 	/**
-	 * Called to create a new TLS connection to a given host.
+	 * Called to create a new connection to a given host.
 	 *
-	 * @param out The created TLS stream
+	 * @param out The created stream
 	 * @param host The hostname to connect to; may be a hostname or
 	 *             IP address
 	 * @param port The port to connect to; may be a port number or
@@ -57,11 +57,12 @@ typedef struct {
 	int (*init)(git_stream **out, const char *host, const char *port);
 
 	/**
-	 * Called to create a new TLS connection on top of the given
-	 * stream.  May be used to proxy a TLS stream over a CONNECT
-	 * session.
+	 * Called to create a new connection on top of the given stream.  If
+	 * this is a TLS stream, then this function may be used to proxy a
+	 * TLS stream over an HTTP CONNECT session.  If this is unset, then
+	 * HTTP CONNECT proxies will not be supported.
 	 *
-	 * @param out The created TLS stream
+	 * @param out The created stream
 	 * @param in An existing stream to add TLS to
 	 * @param host The hostname that the stream is connected to,
 	 *             for certificate validation
@@ -71,17 +72,45 @@ typedef struct {
 } git_stream_registration;
 
 /**
- * Register TLS stream constructors for the library to use
+ * Register stream constructors for the library to use
  *
  * If a registration structure is already set, it will be overwritten.
  * Pass `NULL` in order to deregister the current constructor and return
  * to the system defaults.
  *
  * @param registration the registration data
+ * @param tls 1 if the registration is for TLS streams, 0 for regular
+ *        (insecure) sockets
  * @return 0 or an error code
  */
-GIT_EXTERN(int) git_stream_register_tls(
-	git_stream_registration *registration);
+GIT_EXTERN(int) git_stream_register(
+	int tls, git_stream_registration *registration);
+
+/** @name Deprecated TLS Stream Registration Functions
+ *
+ * These typedefs and functions are retained for backward compatibility.
+ * The newer versions of these functions and structures should be preferred
+ * in all new code.
+ */
+
+/**@{*/
+
+/**
+ * @deprecated Provide a git_stream_registration to git_stream_register
+ * @see git_stream_registration
+ */
+typedef int (*git_stream_cb)(git_stream **out, const char *host, const char *port);
+
+/**
+ * Register a TLS stream constructor for the library to use.  This stream
+ * will not support HTTP CONNECT proxies.
+ *
+ * @deprecated Provide a git_stream_registration to git_stream_register
+ * @see git_stream_register
+ */
+GIT_EXTERN(int) git_stream_register_tls(git_stream_cb ctor);
+
+ /**@}*/
 
 GIT_END_DECL
 

src/global.c

@@ -12,7 +12,7 @@
 #include "sysdir.h"
 #include "filter.h"
 #include "merge_driver.h"
-#include "streams/tls.h"
+#include "streams/registry.h"
 #include "streams/mbedtls.h"
 #include "streams/openssl.h"
 #include "thread-utils.h"
@@ -67,7 +67,7 @@ static int init_common(void)
 		(ret = git_filter_global_init()) == 0 &&
 		(ret = git_merge_driver_global_init()) == 0 &&
 		(ret = git_transport_ssh_global_init()) == 0 &&
-		(ret = git_tls_stream_global_init()) == 0 &&
+		(ret = git_stream_registry_global_init()) == 0 &&
 		(ret = git_openssl_stream_global_init()) == 0 &&
 		(ret = git_mbedtls_stream_global_init()) == 0)
 		ret = git_mwindow_global_init();

src/streams/registry.c

@@ -0,0 +1,99 @@
+/*
+ * Copyright (C) the libgit2 contributors. All rights reserved.
+ *
+ * This file is part of libgit2, distributed under the GNU GPL v2 with
+ * a Linking Exception. For full terms see the included COPYING file.
+ */
+
+#include "git2/errors.h"
+
+#include "common.h"
+#include "global.h"
+#include "streams/tls.h"
+#include "streams/mbedtls.h"
+#include "streams/openssl.h"
+#include "streams/stransport.h"
+
+struct stream_registry {
+	git_rwlock lock;
+	git_stream_registration callbacks;
+	git_stream_registration tls_callbacks;
+};
+
+static struct stream_registry stream_registry;
+
+static void shutdown_stream_registry(void)
+{
+	git_rwlock_free(&stream_registry.lock);
+}
+
+int git_stream_registry_global_init(void)
+{
+	if (git_rwlock_init(&stream_registry.lock) < 0)
+		return -1;
+
+	git__on_shutdown(shutdown_stream_registry);
+	return 0;
+}
+
+int git_stream_registry_lookup(git_stream_registration *out, int tls)
+{
+	git_stream_registration *target = tls ?
+		&stream_registry.callbacks :
+		&stream_registry.tls_callbacks;
+	int error = GIT_ENOTFOUND;
+
+	assert(out);
+
+	if (git_rwlock_rdlock(&stream_registry.lock) < 0) {
+		giterr_set(GITERR_OS, "failed to lock stream registry");
+		return -1;
+	}
+
+	if (target->init) {
+		memcpy(out, target, sizeof(git_stream_registration));
+		error = 0;
+	}
+
+	git_rwlock_rdunlock(&stream_registry.lock);
+	return error;
+}
+
+int git_stream_register(int tls, git_stream_registration *registration)
+{
+	git_stream_registration *target = tls ?
+		&stream_registry.callbacks :
+		&stream_registry.tls_callbacks;
+
+	assert(!registration || registration->init);
+
+	GITERR_CHECK_VERSION(registration, GIT_STREAM_VERSION, "stream_registration");
+
+	if (git_rwlock_wrlock(&stream_registry.lock) < 0) {
+		giterr_set(GITERR_OS, "failed to lock stream registry");
+		return -1;
+	}
+
+	if (registration)
+		memcpy(target, registration, sizeof(git_stream_registration));
+	else
+		memset(target, 0, sizeof(git_stream_registration));
+
+	git_rwlock_wrunlock(&stream_registry.lock);
+	return 0;
+}
+
+int git_stream_register_tls(git_stream_cb ctor)
+{
+	git_stream_registration registration = {0};
+
+	if (ctor) {
+		registration.version = GIT_STREAM_VERSION;
+		registration.init = ctor;
+		registration.wrap = NULL;
+
+		return git_stream_register(1, &registration);
+	} else {
+		return git_stream_register(1, NULL);
+	}
+}

src/streams/registry.h

@@ -0,0 +1,19 @@
+/*
+ * Copyright (C) the libgit2 contributors. All rights reserved.
+ *
+ * This file is part of libgit2, distributed under the GNU GPL v2 with
+ * a Linking Exception. For full terms see the included COPYING file.
+ */
+#ifndef INCLUDE_streams_registry_h__
+#define INCLUDE_streams_registry_h__
+
+#include "common.h"
+#include "git2/sys/stream.h"
+
+/** Configure stream registry. */
+int git_stream_registry_global_init(void);
+
+/** Lookup a stream registration. */
+extern int git_stream_registry_lookup(git_stream_registration *out, int tls);
+
+#endif

src/streams/socket.c

@@ -9,6 +9,7 @@
 
 #include "posix.h"
 #include "netops.h"
+#include "registry.h"
 #include "stream.h"
 
 #ifndef _WIN32
@@ -180,11 +181,14 @@ void socket_free(git_stream *stream)
 	git__free(st);
 }
 
-int git_socket_stream_new(git_stream **out, const char *host, const char *port)
+static int default_socket_stream_new(
+	git_stream **out,
+	const char *host,
+	const char *port)
 {
 	git_socket_stream *st;
 
-	assert(out && host);
+	assert(out && host && port);
 
 	st = git__calloc(1, sizeof(git_socket_stream));
 	GITERR_CHECK_ALLOC(st);
@@ -208,3 +212,29 @@ int git_socket_stream_new(git_stream **out, const char *host, const char *port)
 	*out = (git_stream *) st;
 	return 0;
 }
+
+int git_socket_stream_new(
+	git_stream **out,
+	const char *host,
+	const char *port)
+{
+	int (*init)(git_stream **, const char *, const char *) = NULL;
+	git_stream_registration custom = {0};
+	int error;
+
+	assert(out && host && port);
+
+	if ((error = git_stream_registry_lookup(&custom, 0)) == 0)
+		init = custom.init;
+	else if (error == GIT_ENOTFOUND)
+		init = default_socket_stream_new;
+	else
+		return error;
+
+	if (!init) {
+		giterr_set(GITERR_NET, "there is no socket stream available");
+		return -1;
+	}
+
+	return init(out, host, port);
+}

src/streams/tls.c

@@ -9,78 +9,32 @@
 
 #include "common.h"
 #include "global.h"
+#include "streams/registry.h"
 #include "streams/tls.h"
 #include "streams/mbedtls.h"
 #include "streams/openssl.h"
 #include "streams/stransport.h"
 
-struct git_tls_stream_registration {
-	git_rwlock lock;
-	git_stream_registration callbacks;
-};
-
-static struct git_tls_stream_registration stream_registration;
-
-static void shutdown_ssl(void)
-{
-	git_rwlock_free(&stream_registration.lock);
-}
-
-int git_tls_stream_global_init(void)
-{
-	if (git_rwlock_init(&stream_registration.lock) < 0)
-		return -1;
-
-	git__on_shutdown(shutdown_ssl);
-	return 0;
-}
-
-int git_stream_register_tls(git_stream_registration *registration)
-{
-	assert(!registration || registration->init);
-
-	if (git_rwlock_wrlock(&stream_registration.lock) < 0) {
-		giterr_set(GITERR_OS, "failed to lock stream registration");
-		return -1;
-	}
-
-	if (registration)
-		memcpy(&stream_registration.callbacks, registration,
-		    sizeof(git_stream_registration));
-	else
-		memset(&stream_registration.callbacks, 0,
-		    sizeof(git_stream_registration));
-
-	git_rwlock_wrunlock(&stream_registration.lock);
-	return 0;
-}
-
 int git_tls_stream_new(git_stream **out, const char *host, const char *port)
 {
 	int (*init)(git_stream **, const char *, const char *) = NULL;
+	git_stream_registration custom = {0};
+	int error;
 
 	assert(out && host && port);
 
-	if (git_rwlock_rdlock(&stream_registration.lock) < 0) {
-		giterr_set(GITERR_OS, "failed to lock stream registration");
-		return -1;
-	}
-
-	if (stream_registration.callbacks.init) {
-		init = stream_registration.callbacks.init;
-	} else {
+	if ((error = git_stream_registry_lookup(&custom, 1)) == 0) {
+		init = custom.init;
+	} else if (error == GIT_ENOTFOUND) {
 #ifdef GIT_SECURE_TRANSPORT
 		init = git_stransport_stream_new;
 #elif defined(GIT_OPENSSL)
 		init = git_openssl_stream_new;
 #elif defined(GIT_MBEDTLS)
 		init = git_mbedtls_stream_new;
 #endif
-	}
-
-	if (git_rwlock_rdunlock(&stream_registration.lock) < 0) {
-		giterr_set(GITERR_OS, "failed to unlock stream registration");
-		return -1;
+	} else {
+		return error;
 	}
 
 	if (!init) {
@@ -94,16 +48,12 @@ int git_tls_stream_new(git_stream **out, const char *host, const char *port)
 int git_tls_stream_wrap(git_stream **out, git_stream *in, const char *host)
 {
 	int (*wrap)(git_stream **, git_stream *, const char *) = NULL;
+	git_stream_registration custom = {0};
 
 	assert(out && in);
 
-	if (git_rwlock_rdlock(&stream_registration.lock) < 0) {
-		giterr_set(GITERR_OS, "failed to lock stream registration");
-		return -1;
-	}
-
-	if (stream_registration.callbacks.wrap) {
-		wrap = stream_registration.callbacks.wrap;
+	if (git_stream_registry_lookup(&custom, 1) == 0) {
+		wrap = custom.wrap;
 	} else {
 #ifdef GIT_SECURE_TRANSPORT
 		wrap = git_stransport_stream_wrap;
@@ -114,11 +64,6 @@ int git_tls_stream_wrap(git_stream **out, git_stream *in, const char *host)
 #endif
 	}
 
-	if (git_rwlock_rdunlock(&stream_registration.lock) < 0) {
-		giterr_set(GITERR_OS, "failed to unlock stream registration");
-		return -1;
-	}
-
 	if (!wrap) {
 		giterr_set(GITERR_SSL, "there is no TLS stream available");
 		return -1;

src/streams/tls.h

@@ -11,9 +11,6 @@
 
 #include "git2/sys/stream.h"
 
-/** Configure TLS stream functions. */
-int git_tls_stream_global_init(void);
-
 /**
  * Create a TLS stream with the most appropriate backend available for
  * the current platform, whether that's SecureTransport on macOS,