http: minor cleanups for detect

In preparation of libhtp rust

Mainly adding some const

src/detect-http-cookie.c

@@ -181,7 +181,7 @@ static InspectionBuffer *GetRequestData(DetectEngineThreadCtx *det_ctx,
         if (htp_tx_request_headers(tx) == NULL)
             return NULL;
 
-        htp_header_t *h = (htp_header_t *)htp_tx_request_header(tx, "Cookie");
+        const htp_header_t *h = htp_tx_request_header(tx, "Cookie");
         if (h == NULL || htp_header_value(h) == NULL) {
             SCLogDebug("HTTP cookie header not present in this request");
             return NULL;
@@ -208,7 +208,7 @@ static InspectionBuffer *GetResponseData(DetectEngineThreadCtx *det_ctx,
         if (htp_tx_response_headers(tx) == NULL)
             return NULL;
 
-        htp_header_t *h = (htp_header_t *)htp_tx_response_header(tx, "Set-Cookie");
+        const htp_header_t *h = htp_tx_response_header(tx, "Set-Cookie");
         if (h == NULL || htp_header_value(h) == NULL) {
             SCLogDebug("HTTP cookie header not present in this request");
             return NULL;

src/detect-http-header-names.c

@@ -105,7 +105,7 @@ static uint8_t *GetBufferForTX(
     size_t i = 0;
     size_t no_of_headers = htp_headers_size(headers);
     for (; i < no_of_headers; i++) {
-        htp_header_t *h = htp_headers_get_index(headers, i);
+        const htp_header_t *h = htp_headers_get_index(headers, i);
         size_t size = htp_header_name_len(h) + 2; // for \r\n
         if (i == 0)
             size += 2;

src/detect-http-header.c

@@ -97,7 +97,7 @@ static uint8_t *GetBufferForTX(
     size_t i = 0;
     size_t no_of_headers = htp_headers_size(headers);
     for (; i < no_of_headers; i++) {
-        htp_header_t *h = htp_headers_get_index(headers, i);
+        const htp_header_t *h = htp_headers_get_index(headers, i);
         size_t size1 = htp_header_name_len(h);
         size_t size2 = htp_header_value_len(h);
 
@@ -575,7 +575,7 @@ static InspectionBuffer *GetHttp1HeaderData(DetectEngineThreadCtx *det_ctx,
             hdr_td->cap = no_of_headers;
         }
         for (size_t i = 0; i < no_of_headers; i++) {
-            htp_header_t *h = htp_headers_get_index(headers, i);
+            const htp_header_t *h = htp_headers_get_index(headers, i);
             size_t size1 = htp_header_name_len(h);
             size_t size2 = htp_header_value_len(h);
             size_t size = size1 + size2 + 2;

src/detect-http-host.c

@@ -352,7 +352,7 @@ static InspectionBuffer *GetRawData(DetectEngineThreadCtx *det_ctx,
             if (htp_tx_request_headers(tx) == NULL)
                 return NULL;
 
-            htp_header_t *h = (htp_header_t *)htp_tx_request_header(tx, "Host");
+            const htp_header_t *h = htp_tx_request_header(tx, "Host");
             if (h == NULL || htp_header_value(h) == NULL)
                 return NULL;
 

src/detect-http-protocol.c

@@ -87,7 +87,7 @@ static InspectionBuffer *GetData(DetectEngineThreadCtx *det_ctx,
 {
     InspectionBuffer *buffer = InspectionBufferGet(det_ctx, list_id);
     if (buffer->inspect == NULL) {
-        bstr *str = NULL;
+        const bstr *str = NULL;
         htp_tx_t *tx = (htp_tx_t *)txv;
 
         if (flow_flags & STREAM_TOSERVER)

src/detect-http-start.c

@@ -85,7 +85,7 @@ static uint8_t *GetBufferForTX(
         return NULL;
     }
 
-    bstr *line = NULL;
+    const bstr *line = NULL;
     htp_table_t *headers;
     if (flags & STREAM_TOSERVER) {
         if (AppLayerParserGetStateProgress(IPPROTO_TCP, ALPROTO_HTTP1, tx, flags) <=
@@ -117,7 +117,7 @@ static uint8_t *GetBufferForTX(
     size_t i = 0;
     size_t no_of_headers = htp_headers_size(headers);
     for (; i < no_of_headers; i++) {
-        htp_header_t *h = htp_headers_get_index(headers, i);
+        const htp_header_t *h = htp_headers_get_index(headers, i);
         size_t size1 = htp_header_name_len(h);
         size_t size2 = htp_header_value_len(h);
         size_t size = size1 + size2 + 4;

src/detect-http-ua.c

@@ -165,7 +165,7 @@ static InspectionBuffer *GetData(DetectEngineThreadCtx *det_ctx,
         if (htp_tx_request_headers(tx) == NULL)
             return NULL;
 
-        htp_header_t *h = (htp_header_t *)htp_tx_request_header(tx, "User-Agent");
+        const htp_header_t *h = htp_tx_request_header(tx, "User-Agent");
         if (h == NULL || htp_header_value(h) == NULL) {
             SCLogDebug("HTTP UA header not present in this request");
             return NULL;