openssl: use the curl stream if available

When linking against libcurl, use it as the underlying transport instead
of straight sockets. We can't quite just give over the file descriptor,
as curl puts it into non-blocking mode, so we build a custom BIO so
OpenSSL sends the data through our stream, be it the socket or curl
streams.

src/openssl_stream.c

@@ -16,6 +16,10 @@
 #include "netops.h"
 #include "git2/transport.h"
 
+#ifdef GIT_CURL
+# include "curl_stream.h"
+#endif
+
 #ifndef GIT_WIN32
 # include <sys/types.h>
 # include <sys/socket.h>
@@ -25,6 +29,79 @@
 #include <openssl/ssl.h>
 #include <openssl/err.h>
 #include <openssl/x509v3.h>
+#include <openssl/bio.h>
+
+static int bio_create(BIO *b)
+{
+	b->init = 1;
+	b->num = 0;
+	b->ptr = NULL;
+	b->flags = 0;
+
+	return 1;
+}
+
+static int bio_destroy(BIO *b)
+{
+	if (!b)
+		return 0;
+
+	b->init = 0;
+	b->num = 0;
+	b->ptr = NULL;
+	b->flags = 0;
+
+	return 1;
+}
+
+static int bio_read(BIO *b, char *buf, int len)
+{
+	git_stream *io = (git_stream *) b->ptr;
+	return (int) git_stream_read(io, buf, len);
+}
+
+static int bio_write(BIO *b, const char *buf, int len)
+{
+	git_stream *io = (git_stream *) b->ptr;
+	return (int) git_stream_write(io, buf, len, 0);
+}
+
+static long bio_ctrl(BIO *b, int cmd, long num, void *ptr)
+{
+	GIT_UNUSED(b);
+	GIT_UNUSED(num);
+	GIT_UNUSED(ptr);
+
+	if (cmd == BIO_CTRL_FLUSH)
+		return 1;
+
+	return 0;
+}
+
+static int bio_gets(BIO *b, char *buf, int len)
+{
+	GIT_UNUSED(b);
+	GIT_UNUSED(buf);
+	GIT_UNUSED(len);
+	return -1;
+}
+
+static int bio_puts(BIO *b, const char *str)
+{
+	return bio_write(b, str, strlen(str));
+}
+
+static BIO_METHOD git_stream_bio_method = {
+	BIO_TYPE_SOURCE_SINK,
+	"git_stream",
+	bio_write,
+	bio_read,
+	bio_puts,
+	bio_gets,
+	bio_ctrl,
+	bio_create,
+	bio_destroy
+};
 
 static int ssl_set_error(SSL *ssl, int error)
 {
@@ -224,7 +301,8 @@ cert_fail_name:
 
 typedef struct {
 	git_stream parent;
-	git_socket_stream *socket;
+	git_stream *io;
+	char *host;
 	SSL *ssl;
 	git_cert_x509 cert_info;
 } openssl_stream;
@@ -234,23 +312,24 @@ int openssl_close(git_stream *stream);
 int openssl_connect(git_stream *stream)
 {
 	int ret;
+	BIO *bio;
 	openssl_stream *st = (openssl_stream *) stream;
 
-	if ((ret = git_stream_connect((git_stream *)st->socket)) < 0)
+	if ((ret = git_stream_connect(st->io)) < 0)
 		return ret;
 
-	if ((ret = SSL_set_fd(st->ssl, st->socket->s)) <= 0) {
-		openssl_close((git_stream *) st);
-		return ssl_set_error(st->ssl, ret);
-	}
+	bio = BIO_new(&git_stream_bio_method);
+	GITERR_CHECK_ALLOC(bio);
+	bio->ptr = st->io;
 
+	SSL_set_bio(st->ssl, bio, bio);
 	/* specify the host in case SNI is needed */
-	SSL_set_tlsext_host_name(st->ssl, st->socket->host);
+	SSL_set_tlsext_host_name(st->ssl, st->host);
 
 	if ((ret = SSL_connect(st->ssl)) <= 0)
 		return ssl_set_error(st->ssl, ret);
 
-	return verify_server_cert(st->ssl, st->socket->host);
+	return verify_server_cert(st->ssl, st->host);
 }
 
 int openssl_certificate(git_cert **out, git_stream *stream)
@@ -287,6 +366,13 @@ int openssl_certificate(git_cert **out, git_stream *stream)
 	return 0;
 }
 
+static int openssl_set_proxy(git_stream *stream, const char *proxy_url)
+{
+	openssl_stream *st = (openssl_stream *) stream;
+
+	return git_stream_set_proxy(st->io, proxy_url);
+}
+
 ssize_t openssl_write(git_stream *stream, const char *data, size_t len, int flags)
 {
 	openssl_stream *st = (openssl_stream *) stream;
@@ -320,7 +406,7 @@ int openssl_close(git_stream *stream)
 	if ((ret = ssl_teardown(st->ssl)) < 0)
 		return -1;
 
-	return git_stream_close((git_stream *)st->socket);
+	return git_stream_close(st->io);
 }
 
 void openssl_free(git_stream *stream)
@@ -328,19 +414,26 @@ void openssl_free(git_stream *stream)
 	openssl_stream *st = (openssl_stream *) stream;
 
 	git__free(st->cert_info.data);
-	git_stream_free((git_stream *) st->socket);
+	git_stream_free(st->io);
 	git__free(st);
 }
 
 int git_openssl_stream_new(git_stream **out, const char *host, const char *port)
 {
+	int error;
 	openssl_stream *st;
 
 	st = git__calloc(1, sizeof(openssl_stream));
 	GITERR_CHECK_ALLOC(st);
 
-	if (git_socket_stream_new((git_stream **) &st->socket, host, port))
-		return -1;
+#ifdef GIT_CURL
+	error = git_curl_stream_new(&st->io, host, port, false);
+#else
+	error = git_socket_stream_new(&st->io, host, port)
+#endif
+
+	if (error < 0)
+		return error;
 
 	st->ssl = SSL_new(git__ssl_ctx);
 	if (st->ssl == NULL) {
@@ -348,10 +441,15 @@ int git_openssl_stream_new(git_stream **out, const char *host, const char *port)
 		return -1;
 	}
 
+	st->host = git__strdup(host);
+	GITERR_CHECK_ALLOC(st->host);
+
 	st->parent.version = GIT_STREAM_VERSION;
 	st->parent.encrypted = 1;
+	st->parent.proxy_support = git_stream_supports_proxy(st->io);
 	st->parent.connect = openssl_connect;
 	st->parent.certificate = openssl_certificate;
+	st->parent.set_proxy = openssl_set_proxy;
 	st->parent.read = openssl_read;
 	st->parent.write = openssl_write;
 	st->parent.close = openssl_close;