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/*
* Hash a variable to choose an upstream server.
*
* Copyright (C) Evan Miller
*
* This module can be distributed under the same terms as Nginx itself.
*/
#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_http.h>
#define ngx_bitvector_index(index) index / (8 * sizeof(uintptr_t))
#define ngx_bitvector_bit(index) (uintptr_t) 1 << index % (8 * sizeof(uintptr_t))
typedef struct {
struct sockaddr *sockaddr;
socklen_t socklen;
ngx_str_t name;
} ngx_http_upstream_hash_peer_t;
typedef struct {
ngx_uint_t number;
ngx_http_upstream_hash_peer_t peer[0];
} ngx_http_upstream_hash_peers_t;
typedef struct {
ngx_http_upstream_hash_peers_t *peers;
ngx_uint_t hash;
ngx_str_t current_key;
ngx_str_t original_key;
ngx_uint_t try_i;
uintptr_t tried[1];
} ngx_http_upstream_hash_peer_data_t;
static ngx_int_t ngx_http_upstream_init_hash_peer(ngx_http_request_t *r,
ngx_http_upstream_srv_conf_t *us);
static ngx_int_t ngx_http_upstream_get_hash_peer(ngx_peer_connection_t *pc,
void *data);
static void ngx_http_upstream_free_hash_peer(ngx_peer_connection_t *pc,
void *data, ngx_uint_t state);
static char *ngx_http_upstream_hash(ngx_conf_t *cf, ngx_command_t *cmd,
void *conf);
static char *ngx_http_upstream_hash_again(ngx_conf_t *cf, ngx_command_t *cmd,
void *conf);
static ngx_int_t ngx_http_upstream_init_hash(ngx_conf_t *cf,
ngx_http_upstream_srv_conf_t *us);
static ngx_uint_t ngx_http_upstream_hash_crc32(u_char *keydata, size_t keylen);
static ngx_command_t ngx_http_upstream_hash_commands[] = {
{ ngx_string("hash"),
NGX_HTTP_UPS_CONF|NGX_CONF_TAKE1,
ngx_http_upstream_hash,
0,
0,
NULL },
{ ngx_string("hash_again"),
NGX_HTTP_UPS_CONF|NGX_CONF_TAKE1,
ngx_http_upstream_hash_again,
0,
0,
NULL },
ngx_null_command
};
static ngx_http_module_t ngx_http_upstream_hash_module_ctx = {
NULL, /* preconfiguration */
NULL, /* postconfiguration */
NULL, /* create main configuration */
NULL, /* init main configuration */
NULL, /* create server configuration */
NULL, /* merge server configuration */
NULL, /* create location configuration */
NULL /* merge location configuration */
};
ngx_module_t ngx_http_upstream_hash_module = {
NGX_MODULE_V1,
&ngx_http_upstream_hash_module_ctx, /* module context */
ngx_http_upstream_hash_commands, /* module directives */
NGX_HTTP_MODULE, /* module type */
NULL, /* init master */
NULL, /* init module */
NULL, /* init process */
NULL, /* init thread */
NULL, /* exit thread */
NULL, /* exit process */
NULL, /* exit master */
NGX_MODULE_V1_PADDING
};
static ngx_int_t
ngx_http_upstream_init_hash(ngx_conf_t *cf, ngx_http_upstream_srv_conf_t *us)
{
ngx_uint_t i, j, n;
ngx_http_upstream_server_t *server;
ngx_http_upstream_hash_peers_t *peers;
us->peer.init = ngx_http_upstream_init_hash_peer;
if (!us->servers) {
return NGX_ERROR;
}
server = us->servers->elts;
for (n = 0, i = 0; i < us->servers->nelts; i++) {
n += server[i].naddrs;
}
peers = ngx_pcalloc(cf->pool, sizeof(ngx_http_upstream_hash_peers_t)
+ sizeof(ngx_http_upstream_hash_peer_t) * n);
if (peers == NULL) {
return NGX_ERROR;
}
peers->number = n;
/* one hostname can have multiple IP addresses in DNS */
for (n = 0, i = 0; i < us->servers->nelts; i++) {
for (j = 0; j < server[i].naddrs; j++, n++) {
peers->peer[n].sockaddr = server[i].addrs[j].sockaddr;
peers->peer[n].socklen = server[i].addrs[j].socklen;
peers->peer[n].name = server[i].addrs[j].name;
}
}
us->peer.data = peers;
return NGX_OK;
}
static ngx_int_t
ngx_http_upstream_init_hash_peer(ngx_http_request_t *r,
ngx_http_upstream_srv_conf_t *us)
{
ngx_http_upstream_hash_peer_data_t *uhpd;
ngx_str_t val;
if (ngx_http_script_run(r, &val, us->lengths, 0, us->values) == NULL) {
return NGX_ERROR;
}
uhpd = ngx_pcalloc(r->pool, sizeof(ngx_http_upstream_hash_peer_data_t)
+ sizeof(uintptr_t) *
((ngx_http_upstream_hash_peers_t *)us->peer.data)->number /
(8 * sizeof(uintptr_t)));
if (uhpd == NULL) {
return NGX_ERROR;
}
r->upstream->peer.data = uhpd;
uhpd->peers = us->peer.data;
r->upstream->peer.free = ngx_http_upstream_free_hash_peer;
r->upstream->peer.get = ngx_http_upstream_get_hash_peer;
r->upstream->peer.tries = us->retries + 1;
/* must be big enough for the retry keys */
if ((uhpd->current_key.data = ngx_pcalloc(r->pool, NGX_ATOMIC_T_LEN + val.len)) == NULL) {
return NGX_ERROR;
}
ngx_memcpy(uhpd->current_key.data, val.data, val.len);
uhpd->current_key.len = val.len;
uhpd->original_key = val;
ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
"upstream_hash: hashing \"%V\"", &val);
uhpd->hash = ngx_http_upstream_hash_crc32(val.data, val.len);
return NGX_OK;
}
static ngx_int_t
ngx_http_upstream_get_hash_peer(ngx_peer_connection_t *pc, void *data)
{
ngx_http_upstream_hash_peer_data_t *uhpd = data;
ngx_http_upstream_hash_peer_t *peer;
ngx_uint_t peer_index;
ngx_log_debug1(NGX_LOG_DEBUG_HTTP, pc->log, 0,
"upstream_hash: get upstream request hash peer try %ui", pc->tries);
pc->cached = 0;
pc->connection = NULL;
peer_index = uhpd->hash % uhpd->peers->number;
peer = &uhpd->peers->peer[peer_index];
ngx_log_debug2(NGX_LOG_DEBUG_HTTP, pc->log, 0,
"upstream_hash: chose peer %ui w/ hash %ui", peer_index, uhpd->hash);
pc->sockaddr = peer->sockaddr;
pc->socklen = peer->socklen;
pc->name = &peer->name;
return NGX_OK;
}
/* retry implementation is PECL memcache compatible */
static void
ngx_http_upstream_free_hash_peer(ngx_peer_connection_t *pc, void *data,
ngx_uint_t state)
{
ngx_http_upstream_hash_peer_data_t *uhpd = data;
ngx_uint_t current;
ngx_log_debug1(NGX_LOG_DEBUG_HTTP, pc->log, 0,
"upstream_hash: free upstream hash peer try %ui", pc->tries);
if (state & (NGX_PEER_FAILED|NGX_PEER_NEXT)
&& --pc->tries)
{
current = uhpd->hash % uhpd->peers->number;
uhpd->tried[ngx_bitvector_index(current)] |= ngx_bitvector_bit(current);
do {
uhpd->current_key.len = ngx_sprintf(uhpd->current_key.data, "%d%V",
++uhpd->try_i, &uhpd->original_key) - uhpd->current_key.data;
ngx_log_debug1(NGX_LOG_DEBUG_HTTP, pc->log, 0,
"upstream_hash: hashing \"%V\"", &uhpd->current_key);
uhpd->hash += ngx_http_upstream_hash_crc32(uhpd->current_key.data,
uhpd->current_key.len);
current = uhpd->hash % uhpd->peers->number;
} while ((uhpd->tried[ngx_bitvector_index(current)] & ngx_bitvector_bit(current))
&& --pc->tries);
}
}
/* bit-shift, bit-mask, and non-zero requirement are for libmemcache compatibility */
static ngx_uint_t
ngx_http_upstream_hash_crc32(u_char *keydata, size_t keylen)
{
ngx_uint_t crc32 = (ngx_crc32_short(keydata, keylen) >> 16) & 0x7fff;
return crc32 ? crc32 : 1;
}
static char *
ngx_http_upstream_hash(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
ngx_http_upstream_srv_conf_t *uscf;
ngx_http_script_compile_t sc;
ngx_str_t *value;
ngx_array_t *vars_lengths, *vars_values;
value = cf->args->elts;
ngx_memzero(&sc, sizeof(ngx_http_script_compile_t));
vars_lengths = NULL;
vars_values = NULL;
sc.cf = cf;
sc.source = &value[1];
sc.lengths = &vars_lengths;
sc.values = &vars_values;
sc.complete_lengths = 1;
sc.complete_values = 1;
if (ngx_http_script_compile(&sc) != NGX_OK) {
return NGX_CONF_ERROR;
}
uscf = ngx_http_conf_get_module_srv_conf(cf, ngx_http_upstream_module);
uscf->peer.init_upstream = ngx_http_upstream_init_hash;
uscf->flags = NGX_HTTP_UPSTREAM_CREATE;
uscf->values = vars_values->elts;
uscf->lengths = vars_lengths->elts;
return NGX_CONF_OK;
}
static char *
ngx_http_upstream_hash_again(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
ngx_http_upstream_srv_conf_t *uscf;
ngx_int_t n;
ngx_str_t *value;
uscf = ngx_http_conf_get_module_srv_conf(cf, ngx_http_upstream_module);
value = cf->args->elts;
n = ngx_atoi(value[1].data, value[1].len);
if (n == NGX_ERROR || n < 0) {
return "invalid number";
}
uscf->retries = n;
return NGX_CONF_OK;
}
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