In order to allow for better control flow when protocol_v2 is introduced
convert 'get_remote_heads()' to use 'struct packet_reader' to read
packet lines. This enables a client to be able to peek the first line
of a server's response (without consuming it) in order to determine the
protocol version its speaking and then passing control to the
appropriate handler.
This is needed because the initial response from a server speaking
protocol_v0 includes the first ref, while subsequent protocol versions
respond with a version line. We want to be able to read this first line
without consuming the first ref sent in the protocol_v0 case so that the
protocol version the server is speaking can be determined outside of
'get_remote_heads()' in a future patch.
Signed-off-by: Brandon Williams <bmw...@google.com>
---
connect.c | 125 +++++++++++++++++++++++++++++++++++---------------------------
1 file changed, 70 insertions(+), 55 deletions(-)
diff --git a/connect.c b/connect.c
index 7fbd396b3..f79ea9179 100644
--- a/connect.c
+++ b/connect.c
@@ -48,6 +48,12 @@ int check_ref_type(const struct ref *ref, int flags)
static void die_initial_contact(int unexpected)
{
+ /*
+ * A hang-up after seeing some response from the other end
+ * means that it is unexpected, as we know the other end is
+ * willing to talk to us. A hang-up before seeing any
+ * response does not necessarily mean an ACL problem, though.
+ */
if (unexpected)
die(_("The remote end hung up upon initial contact"));
else
@@ -56,6 +62,41 @@ static void die_initial_contact(int unexpected)
"and the repository exists."));
}
+static enum protocol_version discover_version(struct packet_reader *reader)
+{
+ enum protocol_version version = protocol_unknown_version;
+
+ /*
+ * Peek the first line of the server's response to
+ * determine the protocol version the server is speaking.
+ */
+ switch (packet_reader_peek(reader)) {
+ case PACKET_READ_ERROR:
+ die_initial_contact(0);
+ case PACKET_READ_FLUSH:
+ case PACKET_READ_DELIM:
+ version = protocol_v0;
+ break;
+ case PACKET_READ_NORMAL:
+ version = determine_protocol_version_client(reader->line);
+ break;
+ }
+
+ /* Maybe process capabilities here, at least for v2 */
+ switch (version) {
+ case protocol_v1:
+ /* Read the peeked version line */
+ packet_reader_read(reader);
+ break;
+ case protocol_v0:
+ break;
+ case protocol_unknown_version:
+ BUG("ERROR");
+ }
+
+ return version;
+}
+
static void parse_one_symref_info(struct string_list *symref, const char *val,
int len)
{
char *sym, *target;
@@ -109,44 +150,10 @@ static void annotate_refs_with_symref_info(struct ref
*ref)
string_list_clear(&symref, 0);
}
-/*
- * Read one line of a server's ref advertisement into packet_buffer.
- */
-static int read_remote_ref(int in, char **src_buf, size_t *src_len,
- int *responded)
-{
- int len = packet_read(in, src_buf, src_len,
- packet_buffer, sizeof(packet_buffer),
- PACKET_READ_GENTLE_ON_EOF |
- PACKET_READ_CHOMP_NEWLINE);
- const char *arg;
- if (len < 0)
- die_initial_contact(*responded);
- if (len > 4 && skip_prefix(packet_buffer, "ERR ", &arg))
- die("remote error: %s", arg);
-
- *responded = 1;
-
- return len;
-}
-
-#define EXPECTING_PROTOCOL_VERSION 0
-#define EXPECTING_FIRST_REF 1
-#define EXPECTING_REF 2
-#define EXPECTING_SHALLOW 3
-
-/* Returns 1 if packet_buffer is a protocol version pkt-line, 0 otherwise. */
-static int process_protocol_version(void)
-{
- switch (determine_protocol_version_client(packet_buffer)) {
- case protocol_v1:
- return 1;
- case protocol_v0:
- return 0;
- default:
- die("server is speaking an unknown protocol");
- }
-}
+#define EXPECTING_FIRST_REF 0
+#define EXPECTING_REF 1
+#define EXPECTING_SHALLOW 2
+#define EXPECTING_DONE 3
static void process_capabilities(int *len)
{
@@ -230,28 +237,34 @@ struct ref **get_remote_heads(int in, char *src_buf,
size_t src_len,
struct oid_array *shallow_points)
{
struct ref **orig_list = list;
+ int len = 0;
+ int state = EXPECTING_FIRST_REF;
+ struct packet_reader reader;
+ const char *arg;
- /*
- * A hang-up after seeing some response from the other end
- * means that it is unexpected, as we know the other end is
- * willing to talk to us. A hang-up before seeing any
- * response does not necessarily mean an ACL problem, though.
- */
- int responded = 0;
- int len;
- int state = EXPECTING_PROTOCOL_VERSION;
+ packet_reader_init(&reader, in, src_buf, src_len);
+
+ discover_version(&reader);
*list = NULL;
- while ((len = read_remote_ref(in, &src_buf, &src_len, &responded))) {
+ while (state != EXPECTING_DONE) {
+ switch (packet_reader_read(&reader)) {
+ case PACKET_READ_ERROR:
+ die_initial_contact(1);
+ case PACKET_READ_NORMAL:
+ len = reader.pktlen;
+ if (len > 4 && skip_prefix(packet_buffer, "ERR ", &arg))
+ die("remote error: %s", arg);
+ break;
+ case PACKET_READ_FLUSH:
+ state = EXPECTING_DONE;
+ break;
+ case PACKET_READ_DELIM:
+ die("invalid packet\n");
+ }
+
switch (state) {
- case EXPECTING_PROTOCOL_VERSION:
- if (process_protocol_version()) {
- state = EXPECTING_FIRST_REF;
- break;
- }
- state = EXPECTING_FIRST_REF;
- /* fallthrough */
case EXPECTING_FIRST_REF:
process_capabilities(&len);
if (process_dummy_ref()) {
@@ -269,6 +282,8 @@ struct ref **get_remote_heads(int in, char *src_buf, size_t
src_len,
if (process_shallow(len, shallow_points))
break;
die("protocol error: unexpected '%s'", packet_buffer);
+ case EXPECTING_DONE:
+ break;
default:
die("unexpected state %d", state);
}
--
2.15.1.424.g9478a66081-goog
