http auth: support up to 16 custom headers

Author: Grok Compression

src/lib/core/grok.h

@@ -582,7 +582,10 @@ typedef struct _grk_stream_params
   char username[129]; /* AWS access key ID: max 128 chars + null */
   char password[129]; /* Secret access key: max 128 chars + null */
   char bearer_token[4097]; /* Session token: up to 4096 chars + null */
-  char custom_header[1024]; /* Single header: fits within 8KB total limit */
+#define GRK_MAX_CUSTOM_HEADERS 16
+  char custom_headers[GRK_MAX_CUSTOM_HEADERS][1024]; /* Custom HTTP headers */
+  uint8_t
+      num_custom_headers; /* Number of entries in custom_headers[] (0..GRK_MAX_CUSTOM_HEADERS) */
   char region[64]; /* Region code: max 50 chars + buffer */
 
   /* 5 S3 Endpoint Configuration (for S3-compatible services like MinIO) */

src/lib/core/stream/StreamGenerator.cpp

@@ -128,8 +128,11 @@ IStream* StreamGenerator::createCurlFetchStream(void)
     auth.session_token_ = streamParams_.bearer_token;
   if(streamParams_.region[0])
     auth.region_ = streamParams_.region;
-  if(streamParams_.custom_header[0])
-    auth.custom_header_ = streamParams_.custom_header;
+  for(uint8_t i = 0; i < streamParams_.num_custom_headers; ++i)
+  {
+    if(streamParams_.custom_headers[i][0])
+      auth.custom_headers_.emplace_back(streamParams_.custom_headers[i]);
+  }
   if(streamParams_.s3_endpoint[0])
     auth.s3_endpoint_ = streamParams_.s3_endpoint;
   auth.s3_use_https_ = streamParams_.s3_use_https;

src/lib/core/stream/StreamGenerator.h

@@ -72,7 +72,9 @@ class StreamGenerator
     safe_strcpy(streamParams_.username, src->username);
     safe_strcpy(streamParams_.password, src->password);
     safe_strcpy(streamParams_.bearer_token, src->bearer_token);
-    safe_strcpy(streamParams_.custom_header, src->custom_header);
+    streamParams_.num_custom_headers = src->num_custom_headers;
+    for(uint8_t i = 0; i < src->num_custom_headers; ++i)
+      safe_strcpy(streamParams_.custom_headers[i], src->custom_headers[i]);
     safe_strcpy(streamParams_.region, src->region);
 
     safe_strcpy(streamParams_.s3_endpoint, src->s3_endpoint);

src/lib/core/stream/fetchers/FetchCommon.h

@@ -43,7 +43,7 @@ struct FetchAuth
   std::string username_;
   std::string password_;
   std::string bearer_token_;
-  std::string custom_header_;
+  std::vector<std::string> custom_headers_;
   std::string region_;
   std::string session_token_; // Added for AWS_SESSION_TOKEN
   std::string s3_endpoint_; // Custom S3 endpoint URL (e.g. MinIO)
@@ -80,9 +80,10 @@ struct FetchAuth
   uint32_t retry_delay_ = 0;
 
   FetchAuth() = default;
-  FetchAuth(const std::string& u, const std::string& p, const std::string& t, const std::string& h,
-            const std::string& r = "", const std::string& st = "")
-      : username_(u), password_(p), bearer_token_(t), custom_header_(h), region_(r),
+  FetchAuth(const std::string& u, const std::string& p, const std::string& t,
+            const std::vector<std::string>& h = {}, const std::string& r = "",
+            const std::string& st = "")
+      : username_(u), password_(p), bearer_token_(t), custom_headers_(h), region_(r),
         session_token_(st)
   {}
 };

src/lib/core/stream/fetchers/HTTPFetcher.h

@@ -100,10 +100,10 @@ class HTTPFetcher : public CurlFetcher
       grklog.debug("GRK_HTTP_HEADER_FILE set to %s (not fully implemented)", header_file);
     }
 
-    // Log custom header and bearer token usage
-    if(!auth_.custom_header_.empty())
+    // Log custom headers and bearer token usage
+    for(const auto& hdr : auth_.custom_headers_)
     {
-      grklog.debug("Using custom header: %s", auth_.custom_header_.c_str());
+      grklog.debug("Using custom header: %s", hdr.c_str());
     }
     if(!auth_.bearer_token_.empty())
     {
@@ -113,10 +113,10 @@ class HTTPFetcher : public CurlFetcher
 
   curl_slist* prepareAuthHeaders(curl_slist* headers) override
   {
-    // Add custom header from FetchAuth if provided
-    if(!auth_.custom_header_.empty())
+    // Add custom headers from FetchAuth if provided
+    for(const auto& hdr : auth_.custom_headers_)
     {
-      headers = curl_slist_append(headers, auth_.custom_header_.c_str());
+      headers = curl_slist_append(headers, hdr.c_str());
     }
 
     // Add Authorization header for bearer token if provided