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sock : Add DNS-SRV list sorted by priority and weight, check result connection.

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This commit is contained in:
Chih-Wei Chen
2016-07-18 17:34:26 +08:00
committed by Dmitry Podgorny
parent f46cf669a3
commit 171b285cbe
3 changed files with 152 additions and 47 deletions
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125
src/resolver.c
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@@ -111,23 +111,91 @@ static unsigned message_name_len(const unsigned char *buf, size_t buf_len,
return message_name_get(buf, buf_len, buf_offset, NULL, SIZE_MAX);
}
int resolver_srv_lookup_buf(const unsigned char *buf, size_t len,
char *target, size_t target_len,
unsigned short *port)
int resolver_srv_list_sort(resolver_srv_rr_t **srv_rr_list)
{
int set = 0;
resolver_srv_rr_t * rr_head;
resolver_srv_rr_t * rr_current;
resolver_srv_rr_t * rr_next;
resolver_srv_rr_t * rr_prev;
int swap;
rr_head = *srv_rr_list;
if ((rr_head == NULL) || (rr_head->next == NULL)) {
/* Empty or single record list */
return 0;
}
do {
rr_prev = NULL;
rr_current = rr_head;
rr_next = rr_head->next;
swap = 0;
while (rr_next!=NULL) {
/*
* RFC2052: When selecting a target host among the
* those that have the same priority, the chance of trying
* this one first SHOULD be proportional to its weight.
*/
if ((rr_current->priority > rr_next->priority) ||
(rr_current->priority == rr_next->priority && rr_current->weight < rr_next->weight ))
{
/* Swap node */
swap = 1;
if (rr_prev!=NULL) {
rr_prev->next = rr_next;
} else {
/* Swap head node */
rr_head = rr_next;
}
rr_current->next = rr_next->next;
rr_next->next = rr_current;
rr_prev = rr_next;
rr_next = rr_current->next;
} else {
/* Next node */
rr_prev = rr_current;
rr_current = rr_current->next;
rr_next = rr_current->next;
}
}
}while (swap != 0) ;
*srv_rr_list = rr_head;
return 0;
}
int resolver_srv_list_add(resolver_srv_rr_t **srv_rr_list, resolver_srv_rr_t *srv_rr_data)
{
resolver_srv_rr_t *rr_head;
rr_head = *srv_rr_list;
if (strlen(rr_head->target) > 0) {
srv_rr_data->next = rr_head;
}
*srv_rr_list = srv_rr_data;
return 0;
}
int resolver_srv_lookup_buf(xmpp_ctx_t *ctx, const unsigned char *buf, size_t len,
resolver_srv_rr_t **srv_rr_list)
{
int set = XMPP_DOMAIN_NOT_FOUND;
unsigned i;
unsigned j;
unsigned name_len;
unsigned rdlength;
uint16_t type;
uint16_t class;
uint16_t priority;
uint16_t priority_min;
struct message_header header;
resolver_srv_rr_t *srv_rr_data;
if (len < MESSAGE_HEADER_LEN)
return 0;
return XMPP_DOMAIN_NOT_FOUND;
header.id = xmpp_ntohs_ptr(&buf[0]);
header.octet2 = buf[2];
@@ -139,7 +207,7 @@ int resolver_srv_lookup_buf(const unsigned char *buf, size_t len,
if (message_header_qr(&header) != MESSAGE_RESPONSE ||
message_header_rcode(&header) != 0)
{
return 0;
return XMPP_DOMAIN_NOT_FOUND;
}
j = MESSAGE_HEADER_LEN;
@@ -148,7 +216,7 @@ int resolver_srv_lookup_buf(const unsigned char *buf, size_t len,
name_len = message_name_len(buf, len, j);
if (name_len == 0) {
/* error in name format */
return 0;
return XMPP_DOMAIN_NOT_FOUND;
}
j += name_len + 4;
}
@@ -157,7 +225,6 @@ int resolver_srv_lookup_buf(const unsigned char *buf, size_t len,
* RFC2052: A client MUST attempt to contact the target host
* with the lowest-numbered priority it can reach.
*/
priority_min = UINT16_MAX;
for (i = 0; i < header.ancount; ++i) {
name_len = message_name_len(buf, len, j);
j += name_len;
@@ -166,49 +233,53 @@ int resolver_srv_lookup_buf(const unsigned char *buf, size_t len,
rdlength = xmpp_ntohs_ptr(&buf[j + 8]);
j += 10;
if (type == MESSAGE_T_SRV && class == MESSAGE_C_IN) {
priority = xmpp_ntohs_ptr(&buf[j]);
if (!set || priority < priority_min) {
*port = xmpp_ntohs_ptr(&buf[j + 4]);
name_len = message_name_get(buf, len, j + 6, target, target_len);
set = name_len > 0 ? 1 : 0;
priority_min = priority;
}
srv_rr_data = xmpp_alloc(ctx, sizeof(*srv_rr_data));
srv_rr_data->priority = xmpp_ntohs_ptr(&buf[j]);
srv_rr_data->weight = xmpp_ntohs_ptr(&buf[j+2]);
srv_rr_data->port = xmpp_ntohs_ptr(&buf[j + 4]);
name_len = message_name_get(buf, len, j + 6, &(srv_rr_data->target), MAX_DOMAIN_LEN);
srv_rr_data->next = NULL;
set = name_len > 0 ? XMPP_DOMAIN_FOUND : XMPP_DOMAIN_NOT_FOUND;
resolver_srv_list_add(srv_rr_list,srv_rr_data);
}
j += rdlength;
}
resolver_srv_list_sort(srv_rr_list);
return set;
}
int resolver_srv_lookup(const char *service, const char *proto,
const char *domain, char *target,
size_t target_len, unsigned short *port)
int resolver_srv_lookup(xmpp_ctx_t *ctx, const char *service, const char *proto,
const char *domain, resolver_srv_rr_t **srv_rr_list)
{
char fulldomain[2048];
unsigned char buf[65535];
int len;
int set = 0;
int set = XMPP_DOMAIN_NOT_FOUND;
#ifdef _WIN32
resolver_srv_rr_t *rr;
#endif
xmpp_snprintf(fulldomain, sizeof(fulldomain),
"_%s._%s.%s", service, proto, domain);
#ifdef _WIN32
set = resolver_win32_srv_lookup(fulldomain, target, target_len, port);
if (set)
return set;
rr = xmpp_alloc(ctx, sizeof(*rr));
rr->next = NULL;
set = resolver_win32_srv_lookup(fulldomain, rr->target, sizeof(rr->target), &rr->port);
if (set) *srv_rr_list = rr;
else xmpp_free(ctx, rr);
len = resolver_win32_srv_query(fulldomain, buf, sizeof(buf));
#else /* _WIN32 */
len = res_query(fulldomain, MESSAGE_C_IN, MESSAGE_T_SRV, buf, sizeof(buf));
#endif /* _WIN32 */
if (len > 0)
set = resolver_srv_lookup_buf(buf, (size_t)len, target, target_len, port);
set = resolver_srv_lookup_buf(ctx, buf, (size_t)len, srv_rr_list);
return set;
}
/* FIXME: interface that returns array of results, maybe sorted by priority */
#ifdef _WIN32
/*******************************************************************************