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Gunzip: support multiple content-codings.

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The gunzip filter now accepts Content-Encoding values with multiple
comma-separated codings provided gzip is the last one applied (e.g.
"deflate, gzip"): gzip is stripped from the header, the remaining
codings are preserved, and the outer gzip layer is decompressed.  If
gzip is not the last-applied coding, the response passes through
unchanged.

The Content-Encoding header is rewritten only after gzip_ok has been
evaluated, so when the client accepts gzip and we forward the response
compressed, the header is left intact and matches the body.

This addresses the first TODO in ngx_http_gunzip_header_filter().
This commit is contained in:
David Carlier 2026-04-23 23:02:40 +01:00
parent 5eaf45f11e
commit b6fdba5ada
No known key found for this signature in database
GPG key ID: 1E190B4E2E828ED7
1 changed files with 86 additions and 8 deletions
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94
src/http/modules/ngx_http_gunzip_filter_module.c
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@ -60,6 +60,8 @@ static ngx_int_t ngx_http_gunzip_filter_init(ngx_conf_t *cf);
static void *ngx_http_gunzip_create_conf(ngx_conf_t *cf);
static char *ngx_http_gunzip_merge_conf(ngx_conf_t *cf,
void *parent, void *child);
static ngx_int_t ngx_http_gunzip_rewrite_content_encoding(ngx_http_request_t *r,
ngx_table_elt_t *ce, ngx_str_t *new_value);
static ngx_command_t ngx_http_gunzip_filter_commands[] = {
@ -116,28 +118,100 @@ ngx_module_t ngx_http_gunzip_filter_module = {
static ngx_http_output_header_filter_pt ngx_http_next_header_filter;
static ngx_http_output_body_filter_pt ngx_http_next_body_filter;
static ngx_int_t
ngx_http_gunzip_rewrite_content_encoding(ngx_http_request_t *r,
ngx_table_elt_t *ce, ngx_str_t *new_value)
{
u_char *p, *end, *dst, *token, *out;
size_t len;
ngx_str_t value;
ngx_uint_t first, last;
value = ce->value;
p = value.data;
end = p + value.len;
out = ngx_pnalloc(r->pool, value.len);
if (out == NULL) {
return NGX_ERROR;
}
dst = out;
last = 0;
first = 1;
while (p < end) {
while (p < end && (*p == ' ' || *p == ',')) { p++; }
token = p;
while (p < end && *p != ',') { p++; }
len = p - token;
while (len > 0 && token[len - 1] == ' ') { len--; }
if (len == 4
&& ngx_strncasecmp(token, (u_char *) "gzip", 4) == 0)
{
last = 1;
continue;
}
if (len == 0) {
continue;
}
last = 0;
if (!first) {
*dst++ = ',';
}
dst = ngx_cpymem(dst, token, len);
first = 0;
}
if (!last) {
return NGX_DECLINED;
}
new_value->data = out;
new_value->len = dst - out;
return NGX_OK;
}
static ngx_int_t
ngx_http_gunzip_header_filter(ngx_http_request_t *r)
{
ngx_int_t ret;
ngx_str_t new_value;
ngx_http_gunzip_ctx_t *ctx;
ngx_http_gunzip_conf_t *conf;
conf = ngx_http_get_module_loc_conf(r, ngx_http_gunzip_filter_module);
/* TODO support multiple content-codings */
/* TODO always gunzip - due to configuration or module request */
/* TODO ignore content encoding? */
if (!conf->enable
|| r->headers_out.content_encoding == NULL
|| r->headers_out.content_encoding->value.len != 4
|| ngx_strncasecmp(r->headers_out.content_encoding->value.data,
(u_char *) "gzip", 4) != 0)
|| r->headers_out.content_encoding == NULL)
{
return ngx_http_next_header_filter(r);
}
ret = ngx_http_gunzip_rewrite_content_encoding(r,
r->headers_out.content_encoding,
&new_value);
if (ret == NGX_DECLINED) {
return ngx_http_next_header_filter(r);
}
if (ret == NGX_ERROR) {
return NGX_ERROR;
}
r->gzip_vary = 1;
if (!r->gzip_tested) {
@ -149,6 +223,13 @@ ngx_http_gunzip_header_filter(ngx_http_request_t *r)
return ngx_http_next_header_filter(r);
}
if (new_value.len == 0) {
r->headers_out.content_encoding->hash = 0;
r->headers_out.content_encoding = NULL;
} else {
r->headers_out.content_encoding->value = new_value;
}
ctx = ngx_pcalloc(r->pool, sizeof(ngx_http_gunzip_ctx_t));
if (ctx == NULL) {
return NGX_ERROR;
@ -160,9 +241,6 @@ ngx_http_gunzip_header_filter(ngx_http_request_t *r)
r->filter_need_in_memory = 1;
r->headers_out.content_encoding->hash = 0;
r->headers_out.content_encoding = NULL;
ngx_http_clear_content_length(r);
ngx_http_clear_accept_ranges(r);
ngx_http_weak_etag(r);