Copies the referer/cookie code to allow a header to be specified for forwarding

Author: Kim Dowling

README.md

@@ -38,7 +38,7 @@ CentOS:
   $ sudo rpm -i libapache2-mod-gelf-0.1.0-1.x86_64.rpm
   restart apache
 ```
-    
+
 # Configuration
 
 Load the module in `/etc/apache2/mods-enabled/log_gelf.load`:
@@ -60,15 +60,16 @@ Configure the module in `/etc/apache2/mods-enabled/log_gelf.conf`:
 ```
 On CentOS both files are combined in `/etc/httpd/conf.modules.d/02-gelf.conf`
 
-| Parameter    | Argument               | Description                                   |
-|--------------|------------------------|-----------------------------------------------|
-| GelfEnabled  | On/Off                 | Load GELF logging module                      |
-| GelfUrl      | Graylog server URL     | Set IP and port of a UDP GELF input           |
-| GelfSource   | (Optional)             | Overwrite source field                        |
-| GelfFacility | (Optional)             | Overwrite logging facility                    |
-| GelfTag      | (Optional)             | Add a `tag` field to every log message        |
-| GelfCookie   | (Optional) cookie name | Extract cookie from web request               |
-| GelfFields   | (Optional)             | Configures which information should be logged |
+| Parameter    | Argument               | Description                                       |
+|--------------|------------------------|---------------------------------------------------|
+| GelfEnabled  | On/Off                 | Load GELF logging module                          |
+| GelfUrl      | Graylog server URL     | Set IP and port of a UDP GELF input               |
+| GelfSource   | (Optional)             | Overwrite source field                            |
+| GelfFacility | (Optional)             | Overwrite logging facility                        |
+| GelfTag      | (Optional)             | Add a `tag` field to every log message            |
+| GelfCookie   | (Optional) cookie name | Extract cookie from web request, Use 'c' GelField |
+| GelfHeader   | (Optional) header name | Extract header from web request, Use 'X' GelField |
+| GelfFields   | (Optional)             | Configures which information should be logged     |
 
 What does the `GelfFields` string mean:
 
@@ -97,6 +98,7 @@ What does the `GelfFields` string mean:
 | u         | Username            |
 | V         | Server name         |
 | v         | VirtualHost name    |
+| X         | Extract Header      |
 
 # Packages
 

src/functions.h

@@ -61,11 +61,11 @@ static const char *extract_request_line(request_rec *r, char *a)
 	 * (note the truncation before the protocol string for HTTP/0.9 requests)
 	 * (note also that r->the_request contains the unmodified request)
 	 */
-	return (r->parsed_uri.password) 
+	return (r->parsed_uri.password)
 				? apr_pstrcat(r->pool, r->method, " ",
 					apr_uri_unparse(r->pool,
 						&r->parsed_uri, 0),
-					r->assbackwards ? NULL : " ", 
+					r->assbackwards ? NULL : " ",
 					r->protocol, NULL)
 				: r->the_request;
 }
@@ -148,6 +148,19 @@ static const char *extract_child_pid(request_rec *r, char *a)
     return a;
 }
 
+static const char *extract_header(request_rec *r, char *a)
+{
+	const char *tempref;
+
+	tempref = apr_table_get(r->headers_in, a);
+	if (!tempref)
+	{
+		return "-";
+	} else {
+		return tempref;
+	}
+}
+
 static const char *extract_referer(request_rec *r, char *a)
 {
 	const char *tempref;

src/mod_log_gelf.c

@@ -16,7 +16,7 @@
 
 #define DEFAULT_LOG_FMT "ABDhmsvRti"
 #define UDP 0
-#define TCP 1 
+#define TCP 1
 //#define RECONNECT_INTERVAL 120000000 // reconnect every 2min
 #define RECONNECT_INTERVAL 0
 #define MIN_CONNECTIONS 1
@@ -50,6 +50,7 @@ typedef struct {
   const char          *tag;             /* Optional tag field */
   const char          *fields;          /* String with fields of interest */
   const char          *cookie;          /* Log this cookie */
+  const char          *header;          /* Log this header */
   log_item            **parsed_fields;  /* Link fields to extractor function */
   apr_pool_t          *parse_pool;      /* memory pool for option parsing */
   apr_reslist_t       *connection_pool; /* Connection pool, with min, max and ttl settings */
@@ -98,7 +99,7 @@ void log_gelf_register_item(server_rec *server, apr_pool_t *p,
   item->field_name = field_name;
   if (arg)
     item->arg = arg;
-  
+
   length = strlen(config->fields);
   for (i = 0; i<length; i++) {
     char *pos;
@@ -182,6 +183,12 @@ static const char *set_gelf_cookie(cmd_parms *cmd, void *cfg, const char *arg) {
   config->cookie = arg;
   return NULL;
 }
+/* Override log format string */
+static const char *set_gelf_header(cmd_parms *cmd, void *cfg, const char *arg) {
+  gelf_config *config = ap_get_module_config(cmd->server->module_config, &log_gelf_module);
+  config->header = arg;
+  return NULL;
+}
 
 static const command_rec log_gelf_directives[] = {
   AP_INIT_FLAG("GelfEnabled", set_gelf_enabled, NULL, RSRC_CONF, "Enable or disable GELF logging"),
@@ -191,6 +198,7 @@ static const command_rec log_gelf_directives[] = {
   AP_INIT_TAKE1("GelfTag", set_gelf_tag, NULL, RSRC_CONF, "Set a identification tag"),
   AP_INIT_TAKE1("GelfFields", set_gelf_fields, NULL, RSRC_CONF, "List of fields that should be logged"),
   AP_INIT_TAKE1("GelfCookie", set_gelf_cookie, NULL, RSRC_CONF, "Add this cookie the log message"),
+  AP_INIT_TAKE1("GelfHeader", set_gelf_header, NULL, RSRC_CONF, "Add this header the log message"),
   { NULL }
 };
 
@@ -399,7 +407,8 @@ static int log_gelf_post_config(apr_pool_t *p, apr_pool_t *plog, apr_pool_t *pte
   log_gelf_register_item(server,p,'u', extract_remote_user,       NULL, "_remote_user");
   log_gelf_register_item(server,p,'V', extract_server_name,       NULL, "_server_name");
   log_gelf_register_item(server,p,'v', extract_virtual_host,      NULL, "_virtual_host");
-  
+  log_gelf_register_item(server,p,'X', extract_header,            config->header, "_header");
+
   return OK;
 }
 
@@ -444,7 +453,7 @@ char * log_gelf_make_json(request_rec *request) {
 
   /* init json object */
   json_object* object = json_object_new_object();
-  
+
   /* attach field pairs to json root */
   json_add_string(object, "version", "1.1");
   json_add_string(object, "host", config->source);
@@ -562,7 +571,7 @@ void log_gelf_send_message_udp(const transferData* payload, request_rec *request
   if (!con) {
     return;
   }
-  
+
   if (verbose > 0) {
     log_error(APLOG_MARK, APLOG_ERR, 0, request->server,
       "mod_log_gelf: Sending GELF message: %s", (char*)payload->data);
@@ -600,7 +609,7 @@ void log_gelf_send_message_tcp(const transferData* payload, request_rec *request
   if (!con || !con->s) {
     return;
   }
-  
+
   if (verbose > 0) {
     log_error(APLOG_MARK, APLOG_ERR, 0, request->server,
       "mod_log_gelf: Sending GELF message: %s", gelf_payload);
@@ -656,7 +665,7 @@ static void register_hooks(apr_pool_t *p) {
   ap_hook_log_transaction(log_gelf_transaction, NULL, NULL, APR_HOOK_LAST);
 }
 
-module AP_MODULE_DECLARE_DATA log_gelf_module = { 
+module AP_MODULE_DECLARE_DATA log_gelf_module = {
     STANDARD20_MODULE_STUFF,
     NULL,                       /* Per-directory configuration handler */
     NULL,                       /* Merge handler for per-directory configurations */