Stream: the $upstream_addr variable.

Keeps the full address of the upstream server.  If several servers were
contacted during proxying, their addresses are separated by commas,
e.g. "192.168.1.1:80, 192.168.1.2:80".

src/stream/ngx_stream.h

@@ -172,7 +172,8 @@ struct ngx_stream_session_s {
     void                         **srv_conf;
 
     ngx_stream_upstream_t         *upstream;
-
+    ngx_array_t                   *upstream_states;
+                                           /* of ngx_stream_upstream_state_t */
     ngx_stream_variable_value_t   *variables;
 
 #if (NGX_PCRE)

src/stream/ngx_stream_proxy_module.c

@@ -392,6 +392,13 @@ ngx_stream_proxy_handler(ngx_stream_session_t *s)
     c->write->handler = ngx_stream_proxy_downstream_handler;
     c->read->handler = ngx_stream_proxy_downstream_handler;
 
+    s->upstream_states = ngx_array_create(c->pool, 1,
+                                          sizeof(ngx_stream_upstream_state_t));
+    if (s->upstream_states == NULL) {
+        ngx_stream_proxy_finalize(s, NGX_STREAM_INTERNAL_SERVER_ERROR);
+        return;
+    }
+
     if (c->type == SOCK_STREAM) {
         p = ngx_pnalloc(c->pool, pscf->buffer_size);
         if (p == NULL) {
@@ -677,6 +684,14 @@ ngx_stream_proxy_connect(ngx_stream_session_t *s)
 
     u = s->upstream;
 
+    u->state = ngx_array_push(s->upstream_states);
+    if (u->state == NULL) {
+        ngx_stream_proxy_finalize(s, NGX_STREAM_INTERNAL_SERVER_ERROR);
+        return;
+    }
+
+    ngx_memzero(u->state, sizeof(ngx_stream_upstream_state_t));
+
     rc = ngx_event_connect_peer(&u->peer);
 
     ngx_log_debug1(NGX_LOG_DEBUG_STREAM, c->log, 0, "proxy connect: %i", rc);
@@ -686,6 +701,8 @@ ngx_stream_proxy_connect(ngx_stream_session_t *s)
         return;
     }
 
+    u->state->peer = u->peer.name;
+
     if (rc == NGX_BUSY) {
         ngx_log_error(NGX_LOG_ERR, c->log, 0, "no live upstreams");
         ngx_stream_proxy_finalize(s, NGX_STREAM_BAD_GATEWAY);

src/stream/ngx_stream_upstream.c

@@ -10,6 +10,10 @@
 #include <ngx_stream.h>
 
 
+static ngx_int_t ngx_stream_upstream_add_variables(ngx_conf_t *cf);
+static ngx_int_t ngx_stream_upstream_addr_variable(ngx_stream_session_t *s,
+    ngx_stream_variable_value_t *v, uintptr_t data);
+
 static char *ngx_stream_upstream(ngx_conf_t *cf, ngx_command_t *cmd,
     void *dummy);
 static char *ngx_stream_upstream_server(ngx_conf_t *cf, ngx_command_t *cmd,
@@ -39,7 +43,7 @@ static ngx_command_t  ngx_stream_upstream_commands[] = {
 
 
 static ngx_stream_module_t  ngx_stream_upstream_module_ctx = {
-    NULL,                                  /* preconfiguration */
+    ngx_stream_upstream_add_variables,     /* preconfiguration */
     NULL,                                  /* postconfiguration */
 
     ngx_stream_upstream_create_main_conf,  /* create main configuration */
@@ -66,6 +70,92 @@ ngx_module_t  ngx_stream_upstream_module = {
 };
 
 
+static ngx_stream_variable_t  ngx_stream_upstream_vars[] = {
+
+    { ngx_string("upstream_addr"), NULL,
+      ngx_stream_upstream_addr_variable, 0,
+      NGX_STREAM_VAR_NOCACHEABLE, 0 },
+
+    { ngx_null_string, NULL, NULL, 0, 0, 0 }
+};
+
+
+static ngx_int_t
+ngx_stream_upstream_add_variables(ngx_conf_t *cf)
+{
+    ngx_stream_variable_t  *var, *v;
+
+    for (v = ngx_stream_upstream_vars; v->name.len; v++) {
+        var = ngx_stream_add_variable(cf, &v->name, v->flags);
+        if (var == NULL) {
+            return NGX_ERROR;
+        }
+
+        var->get_handler = v->get_handler;
+        var->data = v->data;
+    }
+
+    return NGX_OK;
+}
+
+
+static ngx_int_t
+ngx_stream_upstream_addr_variable(ngx_stream_session_t *s,
+    ngx_stream_variable_value_t *v, uintptr_t data)
+{
+    u_char                       *p;
+    size_t                        len;
+    ngx_uint_t                    i;
+    ngx_stream_upstream_state_t  *state;
+
+    v->valid = 1;
+    v->no_cacheable = 0;
+    v->not_found = 0;
+
+    if (s->upstream_states == NULL || s->upstream_states->nelts == 0) {
+        v->not_found = 1;
+        return NGX_OK;
+    }
+
+    len = 0;
+    state = s->upstream_states->elts;
+
+    for (i = 0; i < s->upstream_states->nelts; i++) {
+        if (state[i].peer) {
+            len += state[i].peer->len;
+        }
+
+        len += 2;
+    }
+
+    p = ngx_pnalloc(s->connection->pool, len);
+    if (p == NULL) {
+        return NGX_ERROR;
+    }
+
+    v->data = p;
+
+    i = 0;
+
+    for ( ;; ) {
+        if (state[i].peer) {
+            p = ngx_cpymem(p, state[i].peer->data, state[i].peer->len);
+        }
+
+        if (++i == s->upstream_states->nelts) {
+            break;
+        }
+
+        *p++ = ',';
+        *p++ = ' ';
+    }
+
+    v->len = p - v->data;
+
+    return NGX_OK;
+}
+
+
 static char *
 ngx_stream_upstream(ngx_conf_t *cf, ngx_command_t *cmd, void *dummy)
 {

src/stream/ngx_stream_upstream.h

@@ -78,6 +78,11 @@ struct ngx_stream_upstream_srv_conf_s {
 };
 
 
+typedef struct {
+    ngx_str_t                         *peer;
+} ngx_stream_upstream_state_t;
+
+
 typedef struct {
     ngx_str_t                          host;
     in_port_t                          port;
@@ -104,6 +109,7 @@ typedef struct {
     ngx_str_t                          ssl_name;
 #endif
     ngx_stream_upstream_resolved_t    *resolved;
+    ngx_stream_upstream_state_t       *state;
     unsigned                           connected:1;
     unsigned                           proxy_protocol:1;
 } ngx_stream_upstream_t;