This patch adds a "none" option for the "escape" parameter on the
"log_format" directive.

Selecting this option will perform no escaping of variables in the
access log output and write the variable to the file as-is.
The use case for this is more freedom for custom logging setups.

In our case, we use structured logging in JSON. For this, we build a
JSON string in a Lua script that is then stored in a nginx variable.
The log_format in this case is simply the variable:

# The script sets the $json_log variable
log_by_lua_file /etc/nginx/lua/scripts/json_logging.lua;
log_format json $json_log;

access_log /local/nginx/log/access.log json;
error_log /local/nginx/log/error.log;

Both "default" and "json" do not work in this case, since either will
result in invalid JSON output.
Updated test suites for both ngx_http and ngx_stream are provided in
the second patch.


# HG changeset patch
# User Johannes Baiter <johannes.baiter@bsb-muenchen.de>
# Date 1519312196 -3600
# Thu Feb 22 16:09:56 2018 +0100
# Node ID 267e08661efcb58a9b4cd5fd941486b88a37f4f4
# Parent aa60f5799a4cbfc6887ef099c588e84a75c69785
Access log: support for disabling escaping.

diff -r aa60f5799a4c -r 267e08661efc
src/http/modules/ngx_http_log_module.c
--- a/src/http/modules/ngx_http_log_module.c Thu Feb 22 12:42:29 2018
+0300
+++ b/src/http/modules/ngx_http_log_module.c Thu Feb 22 16:09:56 2018
+0100
@@ -90,6 +90,13 @@
} ngx_http_log_var_t;


+typedef enum {
+ ngx_http_log_escape_default = 0,
+ ngx_http_log_escape_json,
+ ngx_http_log_escape_none
+} ngx_http_log_escape_t;
+
+
static void ngx_http_log_write(ngx_http_request_t *r, ngx_http_log_t
*log,
u_char *buf, size_t len);
static ssize_t ngx_http_log_script_write(ngx_http_request_t *r,
@@ -126,12 +133,16 @@
ngx_http_log_op_t *op);

static ngx_int_t ngx_http_log_variable_compile(ngx_conf_t *cf,
- ngx_http_log_op_t *op, ngx_str_t *value, ngx_uint_t json);
+ ngx_http_log_op_t *op, ngx_str_t *value, ngx_http_log_escape_t
escape);
static size_t ngx_http_log_variable_getlen(ngx_http_request_t *r,
uintptr_t data);
static u_char *ngx_http_log_variable(ngx_http_request_t *r, u_char
*buf,
ngx_http_log_op_t *op);
static uintptr_t ngx_http_log_escape(u_char *dst, u_char *src, size_t
size);
+static size_t
ngx_http_log_unescaped_variable_getlen(ngx_http_request_t *r,
+ uintptr_t data);
+static u_char *ngx_http_log_unescaped_variable(ngx_http_request_t *r,
u_char *buf,
+ ngx_http_log_op_t *op);
static size_t ngx_http_log_json_variable_getlen(ngx_http_request_t
*r,
uintptr_t data);
static u_char *ngx_http_log_json_variable(ngx_http_request_t *r,
u_char *buf,
@@ -905,7 +916,7 @@

static ngx_int_t
ngx_http_log_variable_compile(ngx_conf_t *cf, ngx_http_log_op_t *op,
- ngx_str_t *value, ngx_uint_t json)
+ ngx_str_t *value, ngx_http_log_escape_t escape)
{
ngx_int_t index;

@@ -916,10 +927,12 @@

op->len = 0;

- if (json) {
+ if (escape == ngx_http_log_escape_json) {
op->getlen = ngx_http_log_json_variable_getlen;
op->run = ngx_http_log_json_variable;
-
+ } else if (escape == ngx_http_log_escape_none) {
+ op->getlen = ngx_http_log_unescaped_variable_getlen;
+ op->run = ngx_http_log_unescaped_variable;
} else {
op->getlen = ngx_http_log_variable_getlen;
op->run = ngx_http_log_variable;
@@ -1033,6 +1046,38 @@


static size_t
+ngx_http_log_unescaped_variable_getlen(ngx_http_request_t *r,
uintptr_t data)
+{
+ ngx_http_variable_value_t *value;
+
+ value = ngx_http_get_indexed_variable(r, data);
+
+ if (value == NULL || value->not_found) {
+ return 0;
+ }
+
+ value->escape = 0;
+ return value->len;
+}
+
+
+static u_char *
+ngx_http_log_unescaped_variable(ngx_http_request_t *r, u_char *buf,
+ ngx_http_log_op_t *op)
+{
+ ngx_http_variable_value_t *value;
+
+ value = ngx_http_get_indexed_variable(r, op->data);
+
+ if (value == NULL || value->not_found) {
+ return buf;
+ }
+
+ return ngx_cpymem(buf, value->data, value->len);
+}
+
+
+static size_t
ngx_http_log_json_variable_getlen(ngx_http_request_t *r, uintptr_t
data)
{
uintptr_t len;
@@ -1536,19 +1581,21 @@
size_t i, len;
ngx_str_t *value, var;
ngx_int_t *flush;
- ngx_uint_t bracket, json;
+ ngx_uint_t bracket;
ngx_http_log_op_t *op;
ngx_http_log_var_t *v;
+ ngx_http_log_escape_t escape;

- json = 0;
+ escape = ngx_http_log_escape_default;
value = args->elts;

if (s < args->nelts && ngx_strncmp(value[s].data, "escape=", 7) ==
0) {
data = value[s].data + 7;

if (ngx_strcmp(data, "json") == 0) {
- json = 1;
-
+ escape = ngx_http_log_escape_json;
+ } else if (ngx_strcmp(data, "none") == 0) {
+ escape = ngx_http_log_escape_none;
} else if (ngx_strcmp(data, "default") != 0) {
ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
"unknown log format escaping \"%s\"",
data);
@@ -1636,7 +1683,7 @@
}
}

- if (ngx_http_log_variable_compile(cf, op, &var, json)
+ if (ngx_http_log_variable_compile(cf, op, &var,
escape)
!= NGX_OK)
{
return NGX_CONF_ERROR;
diff -r aa60f5799a4c -r 267e08661efc
src/stream/ngx_stream_log_module.c
--- a/src/stream/ngx_stream_log_module.c Thu Feb 22 12:42:29 2018
+0300
+++ b/src/stream/ngx_stream_log_module.c Thu Feb 22 16:09:56 2018
+0100
@@ -89,6 +89,13 @@
} ngx_stream_log_var_t;


+typedef enum {
+ ngx_stream_log_escape_default = 0,
+ ngx_stream_log_escape_json,
+ ngx_stream_log_escape_none
+} ngx_stream_log_escape_t;
+
+
static void ngx_stream_log_write(ngx_stream_session_t *s,
ngx_stream_log_t *log,
u_char *buf, size_t len);
static ssize_t ngx_stream_log_script_write(ngx_stream_session_t *s,
@@ -106,7 +113,7 @@
static void ngx_stream_log_flush_handler(ngx_event_t *ev);

static ngx_int_t ngx_stream_log_variable_compile(ngx_conf_t *cf,
- ngx_stream_log_op_t *op, ngx_str_t *value, ngx_uint_t json);
+ ngx_stream_log_op_t *op, ngx_str_t *value, ngx_stream_log_escape_t
escape);
static size_t ngx_stream_log_variable_getlen(ngx_stream_session_t *s,
uintptr_t data);
static u_char *ngx_stream_log_variable(ngx_stream_session_t *s, u_char
*buf,
@@ -682,7 +689,7 @@

static ngx_int_t
ngx_stream_log_variable_compile(ngx_conf_t *cf, ngx_stream_log_op_t
*op,
- ngx_str_t *value, ngx_uint_t json)
+ ngx_str_t *value, ngx_stream_log_escape_t escape)
{
ngx_int_t index;

@@ -693,10 +700,14 @@

op->len = 0;

- if (json) {
+ if (escape == ngx_stream_log_escape_json) {
op->getlen = ngx_stream_log_json_variable_getlen;
op->run = ngx_stream_log_json_variable;

+ } else if (escape == ngx_stream_log_escape_none) {
+ op->getlen = ngx_stream_log_unescaped_variable_getlen;
+ op->run = ngx_stream_log_unescaped_variable;
+
} else {
op->getlen = ngx_stream_log_variable_getlen;
op->run = ngx_stream_log_variable;
@@ -811,6 +822,38 @@


static size_t
+ngx_stream_log_unescaped_variable_getlen(ngx_stream_session_t *s,
uintptr_t data)
+{
+ ngx_stream_variable_value_t *value;
+
+ value = ngx_stream_get_indexed_variable(s, data);
+
+ if (value == NULL || value->not_found) {
+ return 0;
+ }
+
+ value->escape = 0;
+ return value->len;
+}
+
+
+static u_char *
+ngx_http_log_unescaped_variable(ngx_stream_session_t *s, u_char *buf,
+ ngx_stream_log_op_t *op)
+{
+ ngx_stream_variable_value_t *value;
+
+ value = ngx_stream_get_indexed_variable(s, op->data);
+
+ if (value == NULL || value->not_found) {
+ return buf;
+ }
+
+ return ngx_cpymem(buf, value->data, value->len);
+}
+
+
+static size_t
ngx_stream_log_json_variable_getlen(ngx_stream_session_t *s, uintptr_t
data)
{
uintptr_t len;
@@ -1265,17 +1308,21 @@
size_t i, len;
ngx_str_t *value, var;
ngx_int_t *flush;
- ngx_uint_t bracket, json;
+ ngx_uint_t bracket;
ngx_stream_log_op_t *op;
+ ngx_stream_log_escape_t escape;

- json = 0;
+ escape = ngx_stream_log_escape_default;
value = args->elts;

if (s < args->nelts && ngx_strncmp(value[s].data, "escape=", 7) ==
0) {
data = value[s].data + 7;

if (ngx_strcmp(data, "json") == 0) {
- json = 1;
+ escape = ngx_stream_log_escape_json;
+
+ } else if (ngx_strcmp(data, "none") == 0) {
+ escape = ngx_stream_log_escape_none;

} else if (ngx_strcmp(data, "default") != 0) {
ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
@@ -1350,7 +1397,7 @@
goto invalid;
}

- if (ngx_stream_log_variable_compile(cf, op, &var,
json)
+ if (ngx_stream_log_variable_compile(cf, op, &var,
escape)
!= NGX_OK)
{
return NGX_CONF_ERROR;

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