On Tue, Jun 19, 2012 at 06:47:56PM -0700, Tribble, Alex wrote:
> When nginx gets multiple X-Forwarded-For headers in a single request, it
> only keeps the last one in r->headers_in (and thus in
> $http_x_forwarded_for, $proxy_add_x_forwarded_for). Reverse proxies behind
> an nginx instance sometimes need the entire X-Forwarded-For chain - part
> of which is discarded in this case.
>
> Per RFC 2616, it's equivalent to concatenate each header value (separated
> by a comma) and send the concatenated value to the upstream:
> 4.2
> -snip-
> Multiple message-header fields with the same field-name MAY be
> present in a message if and only if the entire field-value for that
> header field is defined as a comma-separated list [i.e., #(values)].
> It MUST be possible to combine the multiple header fields into one
> "field-name: field-value" pair, without changing the semantics of the
> message, by appending each subsequent field-value to the first, each
> separated by a comma. The order in which header fields with the same
> field-name are received is therefore significant to the
> interpretation of the combined field value, and thus a proxy MUST NOT
> change the order of these field values when a message is forwarded.
> -snip-
>
> Attached is a patch that does exactly this, in the case of multiple headers.
> Please let me know if you have any comments about this patch - I'm happy
> to make any changes you suggest.
>
> Relevant bug report:
> http://trac.nginx.org/nginx/ticket/106

How's this patch instead?

%%%
Index: src/http/ngx_http_request.h
===================================================================
--- src/http/ngx_http_request.h (revision 4698)
+++ src/http/ngx_http_request.h (working copy)
@@ -193,7 +193,7 @@ typedef struct {
ngx_table_elt_t *keep_alive;

#if (NGX_HTTP_X_FORWARDED_FOR)
- ngx_table_elt_t *x_forwarded_for;
+ ngx_array_t x_forwarded_for;
#endif

#if (NGX_HTTP_REALIP)
Index: src/http/ngx_http_request.c
===================================================================
--- src/http/ngx_http_request.c (revision 4698)
+++ src/http/ngx_http_request.c (working copy)
@@ -21,14 +21,14 @@ static ngx_int_t ngx_http_process_header
ngx_table_elt_t *h, ngx_uint_t offset);
static ngx_int_t ngx_http_process_unique_header_line(ngx_http_request_t *r,
ngx_table_elt_t *h, ngx_uint_t offset);
+static ngx_int_t ngx_http_process_multi_header_lines(ngx_http_request_t *r,
+ ngx_table_elt_t *h, ngx_uint_t offset);
static ngx_int_t ngx_http_process_host(ngx_http_request_t *r,
ngx_table_elt_t *h, ngx_uint_t offset);
static ngx_int_t ngx_http_process_connection(ngx_http_request_t *r,
ngx_table_elt_t *h, ngx_uint_t offset);
static ngx_int_t ngx_http_process_user_agent(ngx_http_request_t *r,
ngx_table_elt_t *h, ngx_uint_t offset);
-static ngx_int_t ngx_http_process_cookie(ngx_http_request_t *r,
- ngx_table_elt_t *h, ngx_uint_t offset);

static ngx_int_t ngx_http_process_request_header(ngx_http_request_t *r);
static void ngx_http_process_request(ngx_http_request_t *r);
@@ -141,7 +141,7 @@ ngx_http_header_t ngx_http_headers_in[]
#if (NGX_HTTP_X_FORWARDED_FOR)
{ ngx_string("X-Forwarded-For"),
offsetof(ngx_http_headers_in_t, x_forwarded_for),
- ngx_http_process_header_line },
+ ngx_http_process_multi_header_lines },
#endif

#if (NGX_HTTP_REALIP)
@@ -173,7 +173,8 @@ ngx_http_header_t ngx_http_headers_in[]
ngx_http_process_header_line },
#endif

- { ngx_string("Cookie"), 0, ngx_http_process_cookie },
+ { ngx_string("Cookie"), offsetof(ngx_http_headers_in_t, cookies),
+ ngx_http_process_multi_header_lines },

{ ngx_null_string, 0, NULL }
};
@@ -917,15 +918,6 @@ ngx_http_process_request_line(ngx_event_
return;
}

-
- if (ngx_array_init(&r->headers_in.cookies, r->pool, 2,
- sizeof(ngx_table_elt_t *))
- != NGX_OK)
- {
- ngx_http_close_request(r, NGX_HTTP_INTERNAL_SERVER_ERROR);
- return;
- }
-
c->log->action = "reading client request headers";

rev->handler = ngx_http_process_request_headers;
@@ -1526,20 +1518,31 @@ ngx_http_process_user_agent(ngx_http_req


static ngx_int_t
-ngx_http_process_cookie(ngx_http_request_t *r, ngx_table_elt_t *h,
+ngx_http_process_multi_header_lines(ngx_http_request_t *r, ngx_table_elt_t *h,
ngx_uint_t offset)
{
- ngx_table_elt_t **cookie;
+ ngx_array_t *headers;
+ ngx_table_elt_t **ph;

- cookie = ngx_array_push(&r->headers_in.cookies);
- if (cookie) {
- *cookie = h;
- return NGX_OK;
+ headers = (ngx_array_t *) ((char *) &r->headers_in + offset);
+
+ if (headers->elts == NULL) {
+ if (ngx_array_init(headers, r->pool, 1, sizeof(ngx_table_elt_t *))
+ != NGX_OK)
+ {
+ ngx_http_close_request(r, NGX_HTTP_INTERNAL_SERVER_ERROR);
+ return NGX_ERROR;
+ }
}

- ngx_http_close_request(r, NGX_HTTP_INTERNAL_SERVER_ERROR);
+ ph = ngx_array_push(headers);
+ if (ph == NULL) {
+ ngx_http_close_request(r, NGX_HTTP_INTERNAL_SERVER_ERROR);
+ return NGX_ERROR;
+ }

- return NGX_ERROR;
+ *ph = h;
+ return NGX_OK;
}


Index: src/http/ngx_http_core_module.h
===================================================================
--- src/http/ngx_http_core_module.h (revision 4696)
+++ src/http/ngx_http_core_module.h (working copy)
@@ -514,7 +514,8 @@ ngx_int_t ngx_http_set_disable_symlinks(
ngx_http_core_loc_conf_t *clcf, ngx_str_t *path, ngx_open_file_info_t *of);

ngx_int_t ngx_http_get_forwarded_addr(ngx_http_request_t *r, ngx_addr_t *addr,
- u_char *xff, size_t xfflen, ngx_array_t *proxies, int recursive);
+ ngx_array_t *headers, ngx_str_t *hvalue, ngx_array_t *proxies,
+ int recursive);


extern ngx_module_t ngx_http_core_module;
Index: src/http/ngx_http_core_module.c
===================================================================
--- src/http/ngx_http_core_module.c (revision 4696)
+++ src/http/ngx_http_core_module.c (working copy)
@@ -2699,12 +2699,13 @@ ngx_http_set_disable_symlinks(ngx_http_r
}


-ngx_int_t
-ngx_http_get_forwarded_addr(ngx_http_request_t *r, ngx_addr_t *addr,
+static ngx_int_t
+ngx_http_get_forwarded_addr_iter(ngx_http_request_t *r, ngx_addr_t *addr,
u_char *xff, size_t xfflen, ngx_array_t *proxies, int recursive)
{
u_char *p;
in_addr_t inaddr;
+ ngx_int_t rc;
ngx_addr_t paddr;
ngx_cidr_t *cidr;
ngx_uint_t family, i;
@@ -2788,8 +2789,15 @@ ngx_http_get_forwarded_addr(ngx_http_req
*addr = paddr;

if (recursive && p > xff) {
- (void) ngx_http_get_forwarded_addr(r, addr, xff, p - 1 - xff,
- proxies, 1);
+ rc = ngx_http_get_forwarded_addr_iter(r, addr, xff, p - 1 - xff,
+ proxies, 1);
+
+ if (rc == NGX_DECLINED) {
+ return NGX_DONE;
+ }
+
+ /* rc == NGX_OK || rc == NGX_DONE */
+ return rc;
}

return NGX_OK;
@@ -2802,6 +2810,45 @@ ngx_http_get_forwarded_addr(ngx_http_req
}


+ngx_int_t
+ngx_http_get_forwarded_addr(ngx_http_request_t *r, ngx_addr_t *addr,
+ ngx_array_t *headers, ngx_str_t *hvalue, ngx_array_t *proxies,
+ int recursive)
+{
+ ngx_int_t rc;
+ ngx_uint_t i;
+ ngx_table_elt_t **h;
+
+ if (headers == NULL) {
+ return ngx_http_get_forwarded_addr_iter(r, addr, hvalue->data,
+ hvalue->len, proxies,
+ recursive);
+ }
+
+ i = headers->nelts;
+ h = headers->elts;
+
+ rc = NGX_DECLINED;
+
+ for ( ;; ) {
+ if (i == 0) {
+ break;
+ }
+ i--;
+
+ rc = ngx_http_get_forwarded_addr_iter(r, addr, h[i]->value.data,
+ h[i]->value.len, proxies,
+ recursive);
+
+ if (!recursive || rc != NGX_OK) {
+ break;
+ }
+ }
+
+ return rc;
+}
+
+
static char *
ngx_http_core_server(ngx_conf_t *cf, ngx_command_t *cmd, void *dummy)
{
Index: src/http/ngx_http_variables.c
===================================================================
--- src/http/ngx_http_variables.c (revision 4698)
+++ src/http/ngx_http_variables.c (working copy)
@@ -21,8 +21,14 @@ static void ngx_http_variable_request_se
ngx_http_variable_value_t *v, uintptr_t data);
static ngx_int_t ngx_http_variable_header(ngx_http_request_t *r,
ngx_http_variable_value_t *v, uintptr_t data);
-static ngx_int_t ngx_http_variable_headers(ngx_http_request_t *r,
+static ngx_int_t ngx_http_variable_headers_sep(ngx_http_request_t *r,
+ ngx_http_variable_value_t *v, uintptr_t data, u_char sep);
+static ngx_int_t ngx_http_variable_headers_semi(ngx_http_request_t *r,
ngx_http_variable_value_t *v, uintptr_t data);
+#if (NGX_HTTP_X_FORWARDED_FOR)
+static ngx_int_t ngx_http_variable_headers_comma(ngx_http_request_t *r,
+ ngx_http_variable_value_t *v, uintptr_t data);
+#endif

static ngx_int_t ngx_http_variable_unknown_header_in(ngx_http_request_t *r,
ngx_http_variable_value_t *v, uintptr_t data);
@@ -112,8 +118,8 @@ static ngx_int_t ngx_http_variable_pid(n
*/

/*
- * the $http_host, $http_user_agent, $http_referer, $http_via,
- * and $http_x_forwarded_for variables may be handled by generic
+ * the $http_host, $http_user_agent, $http_referer, and $http_via
+ * variables may be handled by generic
* ngx_http_variable_unknown_header_in(), but for performance reasons
* they are handled using dedicated entries
*/
@@ -135,11 +141,11 @@ static ngx_http_variable_t ngx_http_cor
#endif

#if (NGX_HTTP_X_FORWARDED_FOR)
- { ngx_string("http_x_forwarded_for"), NULL, ngx_http_variable_header,
+ { ngx_string("http_x_forwarded_for"), NULL, ngx_http_variable_headers_comma,
offsetof(ngx_http_request_t, headers_in.x_forwarded_for), 0, 0 },
#endif

- { ngx_string("http_cookie"), NULL, ngx_http_variable_headers,
+ { ngx_string("http_cookie"), NULL, ngx_http_variable_headers_semi,
offsetof(ngx_http_request_t, headers_in.cookies), 0, 0 },

{ ngx_string("content_length"), NULL, ngx_http_variable_header,
@@ -252,7 +258,8 @@ static ngx_http_variable_t ngx_http_cor
{ ngx_string("sent_http_transfer_encoding"), NULL,
ngx_http_variable_sent_transfer_encoding, 0, 0, 0 },

- { ngx_string("sent_http_cache_control"), NULL, ngx_http_variable_headers,
+ { ngx_string("sent_http_cache_control"), NULL,
+ ngx_http_variable_headers_semi,
offsetof(ngx_http_request_t, headers_out.cache_control), 0, 0 },

{ ngx_string("limit_rate"), ngx_http_variable_request_set_size,
@@ -666,8 +673,8 @@ ngx_http_variable_header(ngx_http_reques


static ngx_int_t
-ngx_http_variable_headers(ngx_http_request_t *r, ngx_http_variable_value_t *v,
- uintptr_t data)
+ngx_http_variable_headers_sep(ngx_http_request_t *r,
+ ngx_http_variable_value_t *v, uintptr_t data, u_char sep)
{
size_t len;
u_char *p, *end;
@@ -688,7 +695,7 @@ ngx_http_variable_headers(ngx_http_reque
continue;
}

- len += h[i]->value.len + sizeof("; ") - 1;
+ len += h[i]->value.len + 2;
}

if (len == 0) {
@@ -696,7 +703,7 @@ ngx_http_variable_headers(ngx_http_reque
return NGX_OK;
}

- len -= sizeof("; ") - 1;
+ len -= 2;

v->valid = 1;
v->no_cacheable = 0;
@@ -731,7 +738,7 @@ ngx_http_variable_headers(ngx_http_reque
break;
}

- *p++ = ';'; *p++ = ' ';
+ *p++ = sep; *p++ = ' ';
}

return NGX_OK;
@@ -739,6 +746,26 @@ ngx_http_variable_headers(ngx_http_reque


static ngx_int_t
+ngx_http_variable_headers_semi(ngx_http_request_t *r,
+ ngx_http_variable_value_t *v, uintptr_t data)
+{
+ return ngx_http_variable_headers_sep(r, v, data, ';');
+}
+
+
+#if (NGX_HTTP_X_FORWARDED_FOR)
+
+static ngx_int_t
+ngx_http_variable_headers_comma(ngx_http_request_t *r,
+ ngx_http_variable_value_t *v, uintptr_t data)
+{
+ return ngx_http_variable_headers_sep(r, v, data, ',');
+}
+
+#endif
+
+
+static ngx_int_t
ngx_http_variable_unknown_header_in(ngx_http_request_t *r,
ngx_http_variable_value_t *v, uintptr_t data)
{
Index: src/http/modules/ngx_http_geo_module.c
===================================================================
--- src/http/modules/ngx_http_geo_module.c (revision 4696)
+++ src/http/modules/ngx_http_geo_module.c (working copy)
@@ -215,19 +215,18 @@ static in_addr_t
ngx_http_geo_addr(ngx_http_request_t *r, ngx_http_geo_ctx_t *ctx)
{
ngx_addr_t addr;
- ngx_table_elt_t *xfwd;
+ ngx_array_t *xfwd;
struct sockaddr_in *sin;

if (ngx_http_geo_real_addr(r, ctx, &addr) != NGX_OK) {
return INADDR_NONE;
}

- xfwd = r->headers_in.x_forwarded_for;
+ xfwd = &r->headers_in.x_forwarded_for;

- if (xfwd != NULL && ctx->proxies != NULL) {
- (void) ngx_http_get_forwarded_addr(r, &addr, xfwd->value.data,
- xfwd->value.len, ctx->proxies,
- ctx->proxy_recursive);
+ if (xfwd->elts != NULL && ctx->proxies != NULL) {
+ (void) ngx_http_get_forwarded_addr(r, &addr, xfwd, NULL,
+ ctx->proxies, ctx->proxy_recursive);
}

#if (NGX_HAVE_INET6)
Index: src/http/modules/ngx_http_geoip_module.c
===================================================================
--- src/http/modules/ngx_http_geoip_module.c (revision 4696)
+++ src/http/modules/ngx_http_geoip_module.c (working copy)
@@ -208,19 +208,18 @@ static u_long
ngx_http_geoip_addr(ngx_http_request_t *r, ngx_http_geoip_conf_t *gcf)
{
ngx_addr_t addr;
- ngx_table_elt_t *xfwd;
+ ngx_array_t *xfwd;
struct sockaddr_in *sin;

addr.sockaddr = r->connection->sockaddr;
addr.socklen = r->connection->socklen;
/* addr.name = r->connection->addr_text; */

- xfwd = r->headers_in.x_forwarded_for;
+ xfwd = &r->headers_in.x_forwarded_for;

- if (xfwd != NULL && gcf->proxies != NULL) {
- (void) ngx_http_get_forwarded_addr(r, &addr, xfwd->value.data,
- xfwd->value.len, gcf->proxies,
- gcf->proxy_recursive);
+ if (xfwd->elts != NULL && gcf->proxies != NULL) {
+ (void) ngx_http_get_forwarded_addr(r, &addr, xfwd, NULL,
+ gcf->proxies, gcf->proxy_recursive);
}

#if (NGX_HAVE_INET6)
Index: src/http/modules/ngx_http_proxy_module.c
===================================================================
--- src/http/modules/ngx_http_proxy_module.c (revision 4696)
+++ src/http/modules/ngx_http_proxy_module.c (working copy)
@@ -2260,32 +2260,55 @@ static ngx_int_t
ngx_http_proxy_add_x_forwarded_for_variable(ngx_http_request_t *r,
ngx_http_variable_value_t *v, uintptr_t data)
{
- u_char *p;
+ size_t len;
+ u_char *p;
+ ngx_uint_t i, n;
+ ngx_table_elt_t **h;

v->valid = 1;
v->no_cacheable = 0;
v->not_found = 0;

- if (r->headers_in.x_forwarded_for == NULL) {
+ n = r->headers_in.x_forwarded_for.nelts;
+ h = r->headers_in.x_forwarded_for.elts;
+
+ len = 0;
+
+ for (i = 0; i < n; i++) {
+
+ if (h[i]->hash == 0) {
+ continue;
+ }
+
+ len += h[i]->value.len + sizeof(", ") - 1;
+ }
+
+ if (len == 0) {
v->len = r->connection->addr_text.len;
v->data = r->connection->addr_text.data;
return NGX_OK;
}

- v->len = r->headers_in.x_forwarded_for->value.len
- + sizeof(", ") - 1 + r->connection->addr_text.len;
+ len += r->connection->addr_text.len;

- p = ngx_pnalloc(r->pool, v->len);
+ p = ngx_pnalloc(r->pool, len);
if (p == NULL) {
return NGX_ERROR;
}

+ v->len = len;
v->data = p;

- p = ngx_copy(p, r->headers_in.x_forwarded_for->value.data,
- r->headers_in.x_forwarded_for->value.len);
+ for (i = 0; i < n; i++) {
+
+ if (h[i]->hash == 0) {
+ continue;
+ }
+
+ p = ngx_copy(p, h[i]->value.data, h[i]->value.len);

- *p++ = ','; *p++ = ' ';
+ *p++ = ','; *p++ = ' ';
+ }

ngx_memcpy(p, r->connection->addr_text.data, r->connection->addr_text.len);

Index: src/http/modules/ngx_http_realip_module.c
===================================================================
--- src/http/modules/ngx_http_realip_module.c (revision 4696)
+++ src/http/modules/ngx_http_realip_module.c (working copy)
@@ -107,10 +107,12 @@ ngx_module_t ngx_http_realip_module = {
static ngx_int_t
ngx_http_realip_handler(ngx_http_request_t *r)
{
- u_char *ip, *p;
+ u_char *p;
size_t len;
+ ngx_str_t *hvalue;
ngx_uint_t i, hash;
ngx_addr_t addr;
+ ngx_array_t *xfwd;
ngx_list_part_t *part;
ngx_table_elt_t *header;
ngx_connection_t *c;
@@ -137,19 +139,20 @@ ngx_http_realip_handler(ngx_http_request
return NGX_DECLINED;
}

- len = r->headers_in.x_real_ip->value.len;
- ip = r->headers_in.x_real_ip->value.data;
+ hvalue = &r->headers_in.x_real_ip->value;
+ xfwd = NULL;

break;

case NGX_HTTP_REALIP_XFWD:

- if (r->headers_in.x_forwarded_for == NULL) {
+ xfwd = &r->headers_in.x_forwarded_for;
+
+ if (xfwd->elts == NULL) {
return NGX_DECLINED;
}

- len = r->headers_in.x_forwarded_for->value.len;
- ip = r->headers_in.x_forwarded_for->value.data;
+ hvalue = NULL;

break;

@@ -178,8 +181,8 @@ ngx_http_realip_handler(ngx_http_request
&& len == header[i].key.len
&& ngx_strncmp(p, header[i].lowcase_key, len) == 0)
{
- len = header[i].value.len;
- ip = header[i].value.data;
+ hvalue = &header[i].value;
+ xfwd = NULL;

goto found;
}
@@ -192,15 +195,13 @@ found:

c = r->connection;

- ngx_log_debug1(NGX_LOG_DEBUG_HTTP, c->log, 0, "realip: \"%s\"", ip);
-
addr.sockaddr = c->sockaddr;
addr.socklen = c->socklen;
/* addr.name = c->addr_text; */

- if (ngx_http_get_forwarded_addr(r, &addr, ip, len, rlcf->from,
+ if (ngx_http_get_forwarded_addr(r, &addr, xfwd, hvalue, rlcf->from,
rlcf->recursive)
- == NGX_OK)
+ != NGX_DECLINED)
{
return ngx_http_realip_set_addr(r, &addr);
}
%%%

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