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connect: in ref advertisement, shallows are last 

Currently, get_remote_heads() parses the ref advertisement in one loop,
allowing refs and shallow lines to intersperse, despite this not being
allowed by the specification. Refactor get_remote_heads() to use two
loops instead, enforcing that refs come first, and then shallows.

This also makes it easier to teach get_remote_heads() to interpret other
lines in the ref advertisement, which will be done in a subsequent
patch.

As part of this change, this patch interprets capabilities only on the
first line in the ref advertisement, printing a warning message when
encountering capabilities on other lines.

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Brandon Williams <bmwill@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
maint
Jonathan Tan 2017-09-26 16:56:19 -07:00 committed by Junio C Hamano
parent 7451fcdc0d
commit 0cd83283df
1 changed files with 123 additions and 66 deletions
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189
connect.c
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@ -11,6 +11,7 @@
#include "string-list.h" #include "string-list.h"
#include "sha1-array.h" #include "sha1-array.h"
#include "transport.h" #include "transport.h"
#include "strbuf.h"


static char *server_capabilities; static char *server_capabilities;
static const char *parse_feature_value(const char *, const char *, int *); static const char *parse_feature_value(const char *, const char *, int *);
@ -107,6 +108,104 @@ static void annotate_refs_with_symref_info(struct ref *ref)
string_list_clear(&symref, 0); 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_FIRST_REF 0
#define EXPECTING_REF 1
#define EXPECTING_SHALLOW 2

static void process_capabilities(int *len)
{
int nul_location = strlen(packet_buffer);
if (nul_location == *len)
return;
server_capabilities = xstrdup(packet_buffer + nul_location + 1);
*len = nul_location;
}

static int process_dummy_ref(void)
{
struct object_id oid;
const char *name;

if (parse_oid_hex(packet_buffer, &oid, &name))
return 0;
if (*name != ' ')
return 0;
name++;

return !oidcmp(&null_oid, &oid) && !strcmp(name, "capabilities^{}");
}

static void check_no_capabilities(int len)
{
if (strlen(packet_buffer) != len)
warning("Ignoring capabilities after first line '%s'",
packet_buffer + strlen(packet_buffer));
}

static int process_ref(int len, struct ref ***list, unsigned int flags,
struct oid_array *extra_have)
{
struct object_id old_oid;
const char *name;

if (parse_oid_hex(packet_buffer, &old_oid, &name))
return 0;
if (*name != ' ')
return 0;
name++;

if (extra_have && !strcmp(name, ".have")) {
oid_array_append(extra_have, &old_oid);
} else if (!strcmp(name, "capabilities^{}")) {
die("protocol error: unexpected capabilities^{}");
} else if (check_ref(name, flags)) {
struct ref *ref = alloc_ref(name);
oidcpy(&ref->old_oid, &old_oid);
**list = ref;
*list = &ref->next;
}
check_no_capabilities(len);
return 1;
}

static int process_shallow(int len, struct oid_array *shallow_points)
{
const char *arg;
struct object_id old_oid;

if (!skip_prefix(packet_buffer, "shallow ", &arg))
return 0;

if (get_oid_hex(arg, &old_oid))
die("protocol error: expected shallow sha-1, got '%s'", arg);
if (!shallow_points)
die("repository on the other end cannot be shallow");
oid_array_append(shallow_points, &old_oid);
check_no_capabilities(len);
return 1;
}

/* /*
* Read all the refs from the other end * Read all the refs from the other end
*/ */
@ -123,76 +222,34 @@ struct ref **get_remote_heads(int in, char *src_buf, size_t src_len,
* willing to talk to us. A hang-up before seeing any * willing to talk to us. A hang-up before seeing any
* response does not necessarily mean an ACL problem, though. * response does not necessarily mean an ACL problem, though.
*/ */
int saw_response; int responded = 0;
int got_dummy_ref_with_capabilities_declaration = 0; int len;
int state = EXPECTING_FIRST_REF;


*list = NULL; *list = NULL;
for (saw_response = 0; ; saw_response = 1) {
struct ref *ref;
struct object_id old_oid;
char *name;
int len, name_len;
char *buffer = packet_buffer;
const char *arg;


len = packet_read(in, &src_buf, &src_len, while ((len = read_remote_ref(in, &src_buf, &src_len, &responded))) {
packet_buffer, sizeof(packet_buffer), switch (state) {
PACKET_READ_GENTLE_ON_EOF | case EXPECTING_FIRST_REF:
PACKET_READ_CHOMP_NEWLINE); process_capabilities(&len);
if (len < 0) if (process_dummy_ref()) {
die_initial_contact(saw_response); state = EXPECTING_SHALLOW;

break;
if (!len) }
break; state = EXPECTING_REF;

/* fallthrough */
if (len > 4 && skip_prefix(buffer, "ERR ", &arg)) case EXPECTING_REF:
die("remote error: %s", arg); if (process_ref(len, &list, flags, extra_have))

break;
if (len == GIT_SHA1_HEXSZ + strlen("shallow ") && state = EXPECTING_SHALLOW;
skip_prefix(buffer, "shallow ", &arg)) { /* fallthrough */
if (get_oid_hex(arg, &old_oid)) case EXPECTING_SHALLOW:
die("protocol error: expected shallow sha-1, got '%s'", arg); if (process_shallow(len, shallow_points))
if (!shallow_points) break;
die("repository on the other end cannot be shallow"); die("protocol error: unexpected '%s'", packet_buffer);
oid_array_append(shallow_points, &old_oid); default:
continue; die("unexpected state %d", state);
} }

if (len < GIT_SHA1_HEXSZ + 2 || get_oid_hex(buffer, &old_oid) ||
buffer[GIT_SHA1_HEXSZ] != ' ')
die("protocol error: expected sha/ref, got '%s'", buffer);
name = buffer + GIT_SHA1_HEXSZ + 1;

name_len = strlen(name);
if (len != name_len + GIT_SHA1_HEXSZ + 1) {
free(server_capabilities);
server_capabilities = xstrdup(name + name_len + 1);
}

if (extra_have && !strcmp(name, ".have")) {
oid_array_append(extra_have, &old_oid);
continue;
}

if (!strcmp(name, "capabilities^{}")) {
if (saw_response)
die("protocol error: unexpected capabilities^{}");
if (got_dummy_ref_with_capabilities_declaration)
die("protocol error: multiple capabilities^{}");
got_dummy_ref_with_capabilities_declaration = 1;
continue;
}

if (!check_ref(name, flags))
continue;

if (got_dummy_ref_with_capabilities_declaration)
die("protocol error: unexpected ref after capabilities^{}");

ref = alloc_ref(buffer + GIT_SHA1_HEXSZ + 1);
oidcpy(&ref->old_oid, &old_oid);
*list = ref;
list = &ref->next;
} }


annotate_refs_with_symref_info(*orig_list); annotate_refs_with_symref_info(*orig_list);