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addr: Safeguard last resolved address index access

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The last resolved address cache uses an index that is mapped to an address
family (AF_INET and AF_INET6).

This commit adds a conversion function from af to index and change the code to
use that all the time only.

In the process, this commit fixes a bug that the last resolved address
accessors were using the af value insted of the index.

Spotted by nickm during review

Signed-off-by: David Goulet <dgoulet@torproject.org>
This commit is contained in:
David Goulet 2020-06-24 08:27:24 -04:00
parent 5f62ae2577
commit 5895aafe7e
1 changed files with 30 additions and 17 deletions
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47
src/app/config/resolve_addr.c
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@ -37,13 +37,30 @@
/** Ease our life. Arrays containing state per address family. These are to /** Ease our life. Arrays containing state per address family. These are to
* add semantic to the code so we know what is accessed. */ * add semantic to the code so we know what is accessed. */
#define IDX_IPV4 0 /* Index to AF_INET. */ #define IDX_NULL 0 /* Index to zeroed address object. */
#define IDX_IPV6 1 /* Index to AF_INET6. */ #define IDX_IPV4 1 /* Index to AF_INET. */
#define IDX_SIZE 2 /* How many indexes do we have. */ #define IDX_IPV6 2 /* Index to AF_INET6. */
#define IDX_SIZE 3 /* How many indexes do we have. */
/** Last resolved addresses. */ /** Last resolved addresses. */
static tor_addr_t last_resolved_addrs[IDX_SIZE]; static tor_addr_t last_resolved_addrs[IDX_SIZE];
static inline int
af_to_idx(const int family)
{
switch (family) {
case AF_INET:
return IDX_IPV4;
case AF_INET6:
return IDX_IPV6;
default:
/* It wouldn't be safe to just die here with an assert but we can heavily
* scream with a bug. Return the index of the NULL address. */
tor_assert_nonfatal_unreached();
return IDX_NULL;
}
}
/** Copy the last resolved address of family into addr_out. /** Copy the last resolved address of family into addr_out.
* *
* If not last resolved address existed, the addr_out is a null address (use * If not last resolved address existed, the addr_out is a null address (use
@ -51,7 +68,7 @@ static tor_addr_t last_resolved_addrs[IDX_SIZE];
void void
resolved_addr_get_last(int family, tor_addr_t *addr_out) resolved_addr_get_last(int family, tor_addr_t *addr_out)
{ {
tor_addr_copy(addr_out, &last_resolved_addrs[family]); tor_addr_copy(addr_out, &last_resolved_addrs[af_to_idx(family)]);
} }
/** Reset the last resolved address of family. /** Reset the last resolved address of family.
@ -60,7 +77,7 @@ resolved_addr_get_last(int family, tor_addr_t *addr_out)
void void
resolved_addr_reset_last(int family) resolved_addr_reset_last(int family)
{ {
tor_addr_make_null(&last_resolved_addrs[family], family); tor_addr_make_null(&last_resolved_addrs[af_to_idx(family)], family);
} }
/** @brief Return true iff the given IP address can be used as a valid /** @brief Return true iff the given IP address can be used as a valid
@ -321,7 +338,7 @@ update_resolved_cache(const tor_addr_t *addr, const char *method_used,
const char *hostname_used) const char *hostname_used)
{ {
/** Have we done a first resolve. This is used to control logging. */ /** Have we done a first resolve. This is used to control logging. */
static bool have_resolved_once[IDX_SIZE] = { false, false }; static bool have_resolved_once[IDX_SIZE] = { false, false, false };
bool *done_one_resolve; bool *done_one_resolve;
bool have_hostname = false; bool have_hostname = false;
tor_addr_t *last_resolved; tor_addr_t *last_resolved;
@ -333,20 +350,16 @@ update_resolved_cache(const tor_addr_t *addr, const char *method_used,
/* Do we have an hostname. */ /* Do we have an hostname. */
have_hostname = strlen(hostname_used) > 0; have_hostname = strlen(hostname_used) > 0;
switch (tor_addr_family(addr)) { int idx = af_to_idx(tor_addr_family(addr));
case AF_INET: if (idx == IDX_NULL) {
done_one_resolve = &have_resolved_once[IDX_IPV4]; /* Not suppose to happen and if it does, af_to_idx() screams loudly. */
last_resolved = &last_resolved_addrs[IDX_IPV4];
break;
case AF_INET6:
done_one_resolve = &have_resolved_once[IDX_IPV6];
last_resolved = &last_resolved_addrs[IDX_IPV6];
break;
default:
tor_assert_nonfatal_unreached();
return; return;
} }
/* Get values from cache. */
done_one_resolve = &have_resolved_once[idx];
last_resolved = &last_resolved_addrs[idx];
/* Same address last resolved. Ignore. */ /* Same address last resolved. Ignore. */
if (tor_addr_eq(last_resolved, addr)) { if (tor_addr_eq(last_resolved, addr)) {
return; return;