# HG changeset patch
# User Piotr Sikora <piotrsikora@google.com>
# Date 1466735587 25200
# Thu Jun 23 19:33:07 2016 -0700
# Node ID e21760ce55fdae50a6723aeb4cb6e0b0bcf73dcb
# Parent a96187a9806536ab2a8bf3fa7f7b659cf5d3ff13
Headers filter: add "add_trailer" directive.

Trailers added using this directive are evaluated after response body
is processed by output filters (but before it's written to the wire),
so it's possible to use variables calculated from the response body
as the trailer value.

Signed-off-by: Piotr Sikora <piotrsikora@google.com>

diff -r a96187a98065 -r e21760ce55fd src/http/modules/ngx_http_chunked_filter_module.c
--- a/src/http/modules/ngx_http_chunked_filter_module.c
+++ b/src/http/modules/ngx_http_chunked_filter_module.c
@@ -254,6 +254,10 @@ ngx_http_chunked_get_trailers(ngx_http_r
ngx_table_elt_t *header;
ngx_http_chunked_filter_ctx_t *ctx;

+ if (ngx_http_eval_trailers(r) != NGX_OK) {
+ return NULL;
+ }
+
len = 0;

part = &r->headers_out.trailers.part;
diff -r a96187a98065 -r e21760ce55fd src/http/modules/ngx_http_headers_filter_module.c
--- a/src/http/modules/ngx_http_headers_filter_module.c
+++ b/src/http/modules/ngx_http_headers_filter_module.c
@@ -48,6 +48,7 @@ typedef struct {
time_t expires_time;
ngx_http_complex_value_t *expires_value;
ngx_array_t *headers;
+ ngx_array_t *trailers;
} ngx_http_headers_conf_t;


@@ -72,6 +73,8 @@ static char *ngx_http_headers_expires(ng
void *conf);
static char *ngx_http_headers_add(ngx_conf_t *cf, ngx_command_t *cmd,
void *conf);
+static char *ngx_http_headers_add_trailer(ngx_conf_t *cf, ngx_command_t *cmd,
+ void *conf);


static ngx_http_set_header_t ngx_http_set_headers[] = {
@@ -108,6 +111,14 @@ static ngx_command_t ngx_http_headers_f
0,
NULL},

+ { ngx_string("add_trailer"),
+ NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_HTTP_LIF_CONF
+ |NGX_CONF_TAKE23,
+ ngx_http_headers_add_trailer,
+ NGX_HTTP_LOC_CONF_OFFSET,
+ 0,
+ NULL},
+
ngx_null_command
};

@@ -149,15 +160,23 @@ static ngx_http_output_header_filter_pt
static ngx_int_t
ngx_http_headers_filter(ngx_http_request_t *r)
{
+ u_char *p, *data;
+ size_t len;
ngx_str_t value;
ngx_uint_t i, safe_status;
+ ngx_table_elt_t *t;
ngx_http_header_val_t *h;
ngx_http_headers_conf_t *conf;

+ if (r != r->main) {
+ return ngx_http_next_header_filter(r);
+ }
+
conf = ngx_http_get_module_loc_conf(r, ngx_http_headers_filter_module);

- if ((conf->expires == NGX_HTTP_EXPIRES_OFF && conf->headers == NULL)
- || r != r->main)
+ if (conf->expires == NGX_HTTP_EXPIRES_OFF
+ && conf->headers == NULL
+ && conf->trailers == NULL)
{
return ngx_http_next_header_filter(r);
}
@@ -205,6 +224,64 @@ ngx_http_headers_filter(ngx_http_request
}
}

+ if (conf->trailers && r->trailers_ok) {
+ len = 0;
+
+ h = conf->trailers->elts;
+ for (i = 0; i < conf->trailers->nelts; i++) {
+
+ if (!safe_status && !h[i].always) {
+ continue;
+ }
+
+ if (h[i].value.value.len) {
+ len += h[i].key.len + sizeof(", ") - 1;
+ }
+ }
+
+ if (len == 0) {
+ return ngx_http_next_header_filter(r);
+ }
+
+ len -= sizeof(", ") - 1;
+
+ t = ngx_list_push(&r->headers_out.headers);
+ if (t == NULL) {
+ return NGX_ERROR;
+ }
+
+ data = ngx_pnalloc(r->pool, len);
+ if (data == NULL) {
+ return NGX_ERROR;
+ }
+
+ p = data;
+
+ h = conf->trailers->elts;
+ for (i = 0; i < conf->trailers->nelts; i++) {
+
+ if (!safe_status && !h[i].always) {
+ continue;
+ }
+
+ if (h[i].value.value.len) {
+ p = ngx_copy(p, h[i].key.data, h[i].key.len);
+
+ if (p == data + len) {
+ break;
+ }
+
+ *p++ = ','; *p++ = ' ';
+ }
+ }
+
+ ngx_str_set(&t->key, "Trailer");
+ t->value.data = data;
+ t->value.len = len;
+ t->hash = ngx_hash(ngx_hash(ngx_hash(ngx_hash(ngx_hash(
+ ngx_hash('t', 'r'), 'a'), 'i'), 'l'), 'e'), 'r');
+ }
+
return ngx_http_next_header_filter(r);
}

@@ -541,6 +618,67 @@ ngx_http_set_response_header(ngx_http_re
}


+ngx_int_t
+ngx_http_eval_trailers(ngx_http_request_t *r)
+{
+ ngx_str_t value;
+ ngx_uint_t i, safe_status;
+ ngx_table_elt_t *t;
+ ngx_http_header_val_t *h;
+ ngx_http_headers_conf_t *conf;
+
+ conf = ngx_http_get_module_loc_conf(r, ngx_http_headers_filter_module);
+
+ if (conf->trailers == NULL) {
+ return NGX_OK;
+ }
+
+ switch (r->headers_out.status) {
+
+ case NGX_HTTP_OK:
+ case NGX_HTTP_CREATED:
+ case NGX_HTTP_NO_CONTENT:
+ case NGX_HTTP_PARTIAL_CONTENT:
+ case NGX_HTTP_MOVED_PERMANENTLY:
+ case NGX_HTTP_MOVED_TEMPORARILY:
+ case NGX_HTTP_SEE_OTHER:
+ case NGX_HTTP_NOT_MODIFIED:
+ case NGX_HTTP_TEMPORARY_REDIRECT:
+ safe_status = 1;
+ break;
+
+ default:
+ safe_status = 0;
+ break;
+ }
+
+ h = conf->trailers->elts;
+ for (i = 0; i < conf->trailers->nelts; i++) {
+
+ if (!safe_status && !h[i].always) {
+ continue;
+ }
+
+ if (ngx_http_complex_value(r, &h[i].value, &value) != NGX_OK) {
+ return NGX_ERROR;
+ }
+
+ if (value.len) {
+ t = ngx_list_push(&r->headers_out.trailers);
+ if (t == NULL) {
+ return NGX_ERROR;
+ }
+
+ t->key = h[i].key;
+ t->value = value;
+ t->hash = 1;
+ }
+ }
+
+ return NGX_OK;
+}
+
+
static void *
ngx_http_headers_create_conf(ngx_conf_t *cf)
{
@@ -555,6 +693,7 @@ ngx_http_headers_create_conf(ngx_conf_t
* set by ngx_pcalloc():
*
* conf->headers = NULL;
+ * conf->trailers = NULL;
* conf->expires_time = 0;
* conf->expires_value = NULL;
*/
@@ -585,6 +724,10 @@ ngx_http_headers_merge_conf(ngx_conf_t *
conf->headers = prev->headers;
}

+ if (conf->trailers == NULL) {
+ conf->trailers = prev->trailers;
+ }
+
return NGX_CONF_OK;
}

@@ -739,3 +882,63 @@ ngx_http_headers_add(ngx_conf_t *cf, ngx

return NGX_CONF_OK;
}
+
+
+static char *
+ngx_http_headers_add_trailer(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
+{
+ ngx_http_headers_conf_t *hcf = conf;
+
+ ngx_str_t *value;
+ ngx_http_header_val_t *hv;
+ ngx_http_compile_complex_value_t ccv;
+
+ value = cf->args->elts;
+
+ if (hcf->trailers == NULL) {
+ hcf->trailers = ngx_array_create(cf->pool, 1,
+ sizeof(ngx_http_header_val_t));
+ if (hcf->trailers == NULL) {
+ return NGX_CONF_ERROR;
+ }
+ }
+
+ hv = ngx_array_push(hcf->trailers);
+ if (hv == NULL) {
+ return NGX_CONF_ERROR;
+ }
+
+ hv->key = value[1];
+ hv->handler = NULL;
+ hv->offset = 0;
+ hv->always = 0;
+
+ if (value[2].len == 0) {
+ ngx_memzero(&hv->value, sizeof(ngx_http_complex_value_t));
+
+ } else {
+ ngx_memzero(&ccv, sizeof(ngx_http_compile_complex_value_t));
+
+ ccv.cf = cf;
+ ccv.value = &value[2];
+ ccv.complex_value = &hv->value;
+
+ if (ngx_http_compile_complex_value(&ccv) != NGX_OK) {
+ return NGX_CONF_ERROR;
+ }
+ }
+
+ if (cf->args->nelts == 3) {
+ return NGX_CONF_OK;
+ }
+
+ if (ngx_strcmp(value[3].data, "always") != 0) {
+ ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
+ "invalid parameter \"%V\"", &value[3]);
+ return NGX_CONF_ERROR;
+ }
+
+ hv->always = 1;
+
+ return NGX_CONF_OK;
+}
diff -r a96187a98065 -r e21760ce55fd src/http/ngx_http.h
--- a/src/http/ngx_http.h
+++ b/src/http/ngx_http.h
@@ -146,6 +146,7 @@ ngx_int_t ngx_http_special_response_hand
ngx_int_t ngx_http_filter_finalize_request(ngx_http_request_t *r,
ngx_module_t *m, ngx_int_t error);
void ngx_http_clean_header(ngx_http_request_t *r);
+ngx_int_t ngx_http_eval_trailers(ngx_http_request_t *r);


ngx_int_t ngx_http_discard_request_body(ngx_http_request_t *r);
diff -r a96187a98065 -r e21760ce55fd src/http/v2/ngx_http_v2_filter_module.c
--- a/src/http/v2/ngx_http_v2_filter_module.c
+++ b/src/http/v2/ngx_http_v2_filter_module.c
@@ -606,6 +606,10 @@ ngx_http_v2_create_trailers_frame(ngx_ht
ngx_list_part_t *part;
ngx_table_elt_t *header;

+ if (ngx_http_eval_trailers(r) != NGX_OK) {
+ return NULL;
+ }
+
len = 0;
tmp_len = 0;


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