From f0b27b3b3793eee2295017860545e01905ba2ffe Mon Sep 17 00:00:00 2001
From: Lorenz Stechauner <lorenz.stechauner@necronda.net>
Date: Wed, 17 Aug 2022 19:11:20 +0200
Subject: [PATCH] Fix revproxy and fastcgi http header field merging

---
 src/lib/fastcgi.c   | 2 +-
 src/lib/http.c      | 6 +++---
 src/lib/http.h      | 4 +++-
 src/lib/rev_proxy.c | 2 +-
 4 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/src/lib/fastcgi.c b/src/lib/fastcgi.c
index a9e6945..a9a7707 100644
--- a/src/lib/fastcgi.c
+++ b/src/lib/fastcgi.c
@@ -386,7 +386,7 @@ int fastcgi_header(fastcgi_conn *conn, http_res *res, char *err_msg) {
             return 1;
         }
 
-        ret = http_parse_header_field(&res->hdr, ptr, pos0);
+        ret = http_parse_header_field(&res->hdr, ptr, pos0, 0);
         if (ret != 0) return (int) ret;
         if (pos0[2] == '\r' && pos0[3] == '\n') {
             return 0;
diff --git a/src/lib/http.c b/src/lib/http.c
index 0048bb8..99dfe2b 100644
--- a/src/lib/http.c
+++ b/src/lib/http.c
@@ -83,7 +83,7 @@ void http_free_res(http_res *res) {
     http_free_hdr(&res->hdr);
 }
 
-int http_parse_header_field(http_hdr *hdr, const char *buf, const char *end_ptr) {
+int http_parse_header_field(http_hdr *hdr, const char *buf, const char *end_ptr, int flags) {
     if (hdr->last_field_num > hdr->field_num) {
         print(ERR_STR "Unable to parse header: Invalid state" CLR_STR);
         return 3;
@@ -116,7 +116,7 @@ int http_parse_header_field(http_hdr *hdr, const char *buf, const char *end_ptr)
 
     char field_num = hdr->field_num;
     int found = http_get_header_field_num_len(hdr, buf, len1);
-    if (found == -1) {
+    if (!(flags & HTTP_MERGE_FIELDS) || found == -1) {
         if (http_add_header_field_len(hdr, buf, len1, pos1, len2 < 0 ? 0 : len2) != 0) {
             print(ERR_STR "Unable to parse header: Too many header fields" CLR_STR);
             return 3;
@@ -204,7 +204,7 @@ int http_receive_request(sock *client, http_req *req) {
                 sprintf(req->uri, "%.*s", (int) len, pos1);
                 sprintf(req->version, "%.3s", pos2 + 5);
             } else {
-                int ret = http_parse_header_field(&req->hdr, ptr, pos0);
+                int ret = http_parse_header_field(&req->hdr, ptr, pos0, HTTP_MERGE_FIELDS);
                 if (ret != 0) return ret;
             }
             ptr = pos0 + 2;
diff --git a/src/lib/http.h b/src/lib/http.h
index 4ce1ff7..6d76246 100644
--- a/src/lib/http.h
+++ b/src/lib/http.h
@@ -22,6 +22,8 @@
 #define HTTP_FIELD_EX_VALUE 1
 #define HTTP_FIELD_EX_NAME 2
 
+#define HTTP_MERGE_FIELDS 1
+
 #define HTTP_1XX_STR "\x1B[1;32m"
 #define HTTP_2XX_STR "\x1B[1;32m"
 #define HTTP_3XX_STR "\x1B[1;33m"
@@ -140,7 +142,7 @@ void http_free_res(http_res *res);
 
 int http_receive_request(sock *client, http_req *req);
 
-int http_parse_header_field(http_hdr *hdr, const char *buf, const char *end_ptr) ;
+int http_parse_header_field(http_hdr *hdr, const char *buf, const char *end_ptr, int flags);
 
 const char *http_get_header_field(const http_hdr *hdr, const char *field_name);
 
diff --git a/src/lib/rev_proxy.c b/src/lib/rev_proxy.c
index f8841ba..141d995 100644
--- a/src/lib/rev_proxy.c
+++ b/src/lib/rev_proxy.c
@@ -422,7 +422,7 @@ int rev_proxy_init(http_req *req, http_res *res, http_status_ctx *ctx, host_conf
                 goto proxy_err;
             }
         } else {
-            ret = http_parse_header_field(&res->hdr, ptr, pos0);
+            ret = http_parse_header_field(&res->hdr, ptr, pos0, 0);
             if (ret != 0) {
                 res->status = http_get_status(502);
                 ctx->origin = SERVER_RES;