[PATCH 03 of 20] SCGI: combining headers with identical names (ticket #1724)

[Maxim Dounin]

# HG changeset patch
# User Maxim Dounin <mdounin at mdounin.ru>
# Date 1650492318 -10800
#      Thu Apr 21 01:05:18 2022 +0300
# Node ID 99c3ac43b556830c90ed4e8cf179d429a4830112
# Parent  61b29233a55216c6fa72e23b93a4a28d76a9fb94
SCGI: combining headers with identical names (ticket #1724).

SCGI specification explicitly forbids headers with duplicate names
(section "3. Request Format"): "Duplicate names are not allowed in
the headers".

Further, provided headers are expected to follow CGI specification,
which also requires to combine headers (RFC 3875, section "4.1.18.
Protocol-Specific Meta-Variables"): "If multiple header fields with
the same field-name are received then the server MUST rewrite them
as a single value having the same semantics".

diff --git a/src/http/modules/ngx_http_scgi_module.c b/src/http/modules/ngx_http_scgi_module.c
--- a/src/http/modules/ngx_http_scgi_module.c
+++ b/src/http/modules/ngx_http_scgi_module.c
@@ -633,14 +633,14 @@ static ngx_int_t
 ngx_http_scgi_create_request(ngx_http_request_t *r)
 {
     off_t                         content_length_n;
-    u_char                        ch, *key, *val, *lowcase_key;
+    u_char                        ch, sep, *key, *val, *lowcase_key;
     size_t                        len, key_len, val_len, allocated;
     ngx_buf_t                    *b;
     ngx_str_t                     content_length;
     ngx_uint_t                    i, n, hash, skip_empty, header_params;
     ngx_chain_t                  *cl, *body;
     ngx_list_part_t              *part;
-    ngx_table_elt_t              *header, **ignored;
+    ngx_table_elt_t              *header, *hn, **ignored;
     ngx_http_scgi_params_t       *params;
     ngx_http_script_code_pt       code;
     ngx_http_script_engine_t      e, le;
@@ -707,7 +707,11 @@ ngx_http_scgi_create_request(ngx_http_re
         allocated = 0;
         lowcase_key = NULL;
 
-        if (params->number) {
+        if (ngx_http_link_multi_headers(r) != NGX_OK) {
+            return NGX_ERROR;
+        }
+
+        if (params->number || r->headers_in.multi) {
             n = 0;
             part = &r->headers_in.headers.part;
 
@@ -737,6 +741,12 @@ ngx_http_scgi_create_request(ngx_http_re
                 i = 0;
             }
 
+            for (n = 0; n < header_params; n++) {
+                if (&header[i] == ignored[n]) {
+                    goto next_length;
+                }
+            }
+
             if (params->number) {
                 if (allocated < header[i].key.len) {
                     allocated = header[i].key.len + 16;
@@ -770,6 +780,15 @@ ngx_http_scgi_create_request(ngx_http_re
 
             len += sizeof("HTTP_") - 1 + header[i].key.len + 1
                 + header[i].value.len + 1;
+
+            for (hn = header[i].next; hn; hn = hn->next) {
+                len += hn->value.len + 2;
+                ignored[header_params++] = hn;
+            }
+
+        next_length:
+
+            continue;
         }
     }
 
@@ -869,7 +888,7 @@ ngx_http_scgi_create_request(ngx_http_re
 
             for (n = 0; n < header_params; n++) {
                 if (&header[i] == ignored[n]) {
-                    goto next;
+                    goto next_value;
                 }
             }
 
@@ -893,12 +912,33 @@ ngx_http_scgi_create_request(ngx_http_re
 
             val = b->last;
             b->last = ngx_copy(val, header[i].value.data, header[i].value.len);
+
+            if (header[i].next) {
+
+                if (header[i].key.len == sizeof("Cookie") - 1
+                    && ngx_strncasecmp(header[i].key.data, (u_char *) "Cookie",
+                                       sizeof("Cookie") - 1)
+                       == 0)
+                {
+                    sep = ';';
+
+                } else {
+                    sep = ',';
+                }
+
+                for (hn = header[i].next; hn; hn = hn->next) {
+                    *b->last++ = sep;
+                    *b->last++ = ' ';
+                    b->last = ngx_copy(b->last, hn->value.data, hn->value.len);
+                }
+            }
+
             *b->last++ = (u_char) 0;
 
             ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                            "scgi param: \"%s: %s\"", key, val);
 
-        next:
+        next_value:
 
             continue;
         }