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kexinit_algorithm: switch to storing names as ptrlen.

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They're now also compared as strings, fixing the slight fragility
where we depended on string-literal pointer equality.
This commit is contained in:
Simon Tatham 2022-04-20 10:33:08 +01:00
parent 3a54f28a4e
commit 6a9e4ba24a
2 changed files with 18 additions and 12 deletions
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28
ssh/transport2.c
View File

@ -302,17 +302,17 @@ static void ssh2_mkkey(
* Find a slot in a KEXINIT algorithm list to use for a new algorithm. * Find a slot in a KEXINIT algorithm list to use for a new algorithm.
* If the algorithm is already in the list, return a pointer to its * If the algorithm is already in the list, return a pointer to its
* entry, otherwise return an entry from the end of the list. * entry, otherwise return an entry from the end of the list.
* This assumes that every time a particular name is passed in, it *
* comes from the same string constant. If this isn't true, this * 'name' is expected to be a ptrlen which it's safe to keep a copy
* function may need to be rewritten to use strcmp() instead. * of.
*/ */
static struct kexinit_algorithm *ssh2_kexinit_addalg(struct kexinit_algorithm static struct kexinit_algorithm *ssh2_kexinit_addalg_pl(
*list, const char *name) struct kexinit_algorithm *list, ptrlen name)
{ {
int i; int i;
for (i = 0; i < MAXKEXLIST; i++) for (i = 0; i < MAXKEXLIST; i++)
if (list[i].name == NULL || list[i].name == name) { if (list[i].name.ptr == NULL || ptrlen_eq_ptrlen(list[i].name, name)) {
list[i].name = name; list[i].name = name;
return &list[i]; return &list[i];
} }
@ -320,6 +320,12 @@ static struct kexinit_algorithm *ssh2_kexinit_addalg(struct kexinit_algorithm
unreachable("Should never run out of space in KEXINIT list"); unreachable("Should never run out of space in KEXINIT list");
} }
static struct kexinit_algorithm *ssh2_kexinit_addalg(
struct kexinit_algorithm *list, const char *name)
{
return ssh2_kexinit_addalg_pl(list, ptrlen_from_asciz(name));
}
bool ssh2_common_filter_queue(PacketProtocolLayer *ppl) bool ssh2_common_filter_queue(PacketProtocolLayer *ppl)
{ {
static const char *const ssh2_disconnect_reasons[] = { static const char *const ssh2_disconnect_reasons[] = {
@ -606,7 +612,7 @@ static void ssh2_write_kexinit_lists(
for (i = 0; i < NKEXLIST; i++) for (i = 0; i < NKEXLIST; i++)
for (j = 0; j < MAXKEXLIST; j++) for (j = 0; j < MAXKEXLIST; j++)
kexlists[i][j].name = NULL; kexlists[i][j].name = make_ptrlen(NULL, 0);
/* List key exchange algorithms. */ /* List key exchange algorithms. */
warn = false; warn = false;
for (i = 0; i < n_preferred_kex; i++) { for (i = 0; i < n_preferred_kex; i++) {
@ -832,8 +838,8 @@ static void ssh2_write_kexinit_lists(
put_datapl(list, ssc->kex_override[i]); put_datapl(list, ssc->kex_override[i]);
} else { } else {
for (j = 0; j < MAXKEXLIST; j++) { for (j = 0; j < MAXKEXLIST; j++) {
if (kexlists[i][j].name == NULL) break; if (kexlists[i][j].name.ptr == NULL) break;
add_to_commasep(list, kexlists[i][j].name); add_to_commasep_pl(list, kexlists[i][j].name);
} }
} }
if (i == KEXLIST_KEX && first_time) { if (i == KEXLIST_KEX && first_time) {
@ -923,8 +929,8 @@ static bool ssh2_scan_kexinits(
selected[i] = NULL; selected[i] = NULL;
for (j = 0; j < MAXKEXLIST; j++) { for (j = 0; j < MAXKEXLIST; j++) {
if (kexlists[i][j].name && if (kexlists[i][j].name.ptr &&
ptrlen_eq_string(found, kexlists[i][j].name)) { ptrlen_eq_ptrlen(found, kexlists[i][j].name)) {
selected[i] = &kexlists[i][j]; selected[i] = &kexlists[i][j];
break; break;
} }

2
ssh/transport2.h
View File

@ -20,7 +20,7 @@
#define MAXKEXLIST 16 #define MAXKEXLIST 16
struct kexinit_algorithm { struct kexinit_algorithm {
const char *name; ptrlen name;
union { union {
struct { struct {
const ssh_kex *kex; const ssh_kex *kex;