HTTP: compress: added configurable threshold for Content-Length.

With this, short responses, that is, responses with a body of up to
content_length_threshold bytes, won't be compressed.  The default value
is 20, as in NGINX.

Signed-off-by: Alejandro Colomar <alx@nginx.com>

4 files changed, 42 insertions, 6 deletions

diff --git a/src/nxt_conf_validation.c b/src/nxt_conf_validation.c
index 4943c603..7e1da709 100644
--- a/src/nxt_conf_validation.c
+++ b/src/nxt_conf_validation.c
@@ -1161,6 +1161,9 @@ static nxt_conf_vldt_object_t  nxt_conf_vldt_compress_members[] = {
     }, {
         .name       = nxt_string("level"),
         .type       = NXT_CONF_VLDT_INTEGER,
+    }, {
+        .name       = nxt_string("min_length"),
+        .type       = NXT_CONF_VLDT_INTEGER,
     },
 
     NXT_CONF_VLDT_END
diff --git a/src/nxt_http_compress.c b/src/nxt_http_compress.c
index 55e20e3a..763d1266 100644
--- a/src/nxt_http_compress.c
+++ b/src/nxt_http_compress.c
@@ -37,6 +37,11 @@ static nxt_conf_map_t  nxt_http_compress_conf[] = {
         NXT_CONF_MAP_INT8,
         offsetof(nxt_http_compress_conf_t, level),
     },
+    {
+        nxt_string("min_length"),
+        NXT_CONF_MAP_SIZE,
+        offsetof(nxt_http_compress_conf_t, min_len),
+    },
 };
 
 
@@ -56,6 +61,7 @@ nxt_http_compress_init(nxt_router_conf_t *rtcf, nxt_http_action_t *action,
     }
 
     conf->level = NXT_DEFAULT_COMPRESSION;
+    conf->min_len = 20;
 
     ret = nxt_conf_map_object(mp, acf->compress, nxt_http_compress_conf,
                               nxt_nitems(nxt_http_compress_conf), conf);
@@ -98,3 +104,30 @@ nxt_http_compress_append_field(nxt_task_t *task, nxt_http_request_t *r,
 
     return NXT_OK;
 }
+
+
+ssize_t
+nxt_http_compress_resp_content_length(nxt_http_response_t *resp)
+{
+    size_t     cl;
+    nxt_int_t  err;
+    nxt_str_t  str;
+
+    if (resp->content_length_n != -1) {
+        return resp->content_length_n;
+    }
+
+    if (resp->content_length == NULL) {
+        return -1;
+    }
+
+    str.length = resp->content_length->value_length;
+    str.start = resp->content_length->value;
+
+    cl = nxt_ustrtoul(&str, &err);
+    if (err == NXT_ERROR) {
+        return -1;
+    }
+
+    return cl;
+}
diff --git a/src/nxt_http_compress.h b/src/nxt_http_compress.h
index 19075025..6e8e45f9 100644
--- a/src/nxt_http_compress.h
+++ b/src/nxt_http_compress.h
@@ -9,6 +9,7 @@
 
 #include "nxt_router.h"
 
+#include <stddef.h>
 #include <stdint.h>
 
 #include "nxt_http.h"
@@ -26,12 +27,14 @@ struct nxt_http_compress_conf_s {
                           nxt_http_compress_conf_t *conf);
 
     int8_t     level;
+    size_t     min_len;
 };
 
 
 nxt_int_t nxt_http_compress_init(nxt_router_conf_t *rtcf,
     nxt_http_action_t *action, nxt_http_action_conf_t *acf);
 
+ssize_t nxt_http_compress_resp_content_length(nxt_http_response_t *resp);
 nxt_int_t nxt_http_compress_append_field(nxt_task_t *task,
     nxt_http_request_t *r, nxt_str_t *field, nxt_str_t *value);
 
diff --git a/src/nxt_http_compress_gzip.c b/src/nxt_http_compress_gzip.c
index db675ecf..2d0d65ae 100644
--- a/src/nxt_http_compress_gzip.c
+++ b/src/nxt_http_compress_gzip.c
@@ -54,18 +54,15 @@ nxt_int_t
 nxt_http_compress_gzip(nxt_task_t *task, nxt_http_request_t *r,
     nxt_http_compress_conf_t *conf)
 {
+    size_t                        clen;
     nxt_int_t                     ret;
     nxt_http_compress_gzip_ctx_t  *ctx;
 
     static nxt_str_t  ce = nxt_string("Content-Encoding");
     static nxt_str_t  gzip = nxt_string("gzip");
 
-    if (r->body_handler == NULL
-        || r->resp.content_length_n == 0
-        || (r->resp.content_length != NULL
-            && r->resp.content_length->value_length == 1
-            && r->resp.content_length->value[0] == '0'))
-    {
+    clen = nxt_http_compress_resp_content_length(&r->resp);
+    if (clen < nxt_max(1u, conf->min_len) || r->body_handler == NULL) {
         return NXT_OK;
     }