AddLog Example

The example in this section demonstrates how to implement brief-log, a custom SAF for logging only three items of information about a request: the IP address, the method, and the URI (for example, 198.93.95.99 GET /jocelyn/dogs/homesneeded.html).

Installing the Example

To load the shared object containing your functions, add the following line in the Init section of the magnus.conf file:

Init fn=load-modules shlib=yourlibrary funcs=brief-init,brief-log

To call brief-init to open the log file, add the following line to the Init section in magnus.conf. (This line must come after the one that loads the library containing brief-init.)

Init fn=brief-init file=/tmp/brief.log

To execute your custom SAF during the AddLog stage for some object, add the following line to that object in the obj.conf file:

AddLog fn=brief-log

Source Code

The source code is in addlog.c file in the nsapi/examples/ or plugins/nsapi/examples subdirectory within the server root directory.

#include "nsapi.h"
#include "base/daemon.h" /* daemon_atrestart */
#include "base/file.h"   /* system_fopenWA, system_fclose */
#include "base/util.h"   /* sprintf */


/* File descriptor to be shared between the processes */

static SYS_FILE logfd = SYS_ERROR_FD;

#ifdef __cplusplus
extern "C"
#endif
NSAPI_PUBLIC void brief_terminate(void *parameter)
{
    system_fclose(logfd);
    logfd = SYS_ERROR_FD;
}

#ifdef __cplusplus
extern "C"
#endif
NSAPI_PUBLIC int brief_init(pblock *pb, Session *sn, Request *rq)
{
    /* Parameter */
    char *fn = pblock_findval("file", pb);

    if(!fn) {
        pblock_nvinsert("error", "brief-init: please supply a file name", pb);
        return REQ_ABORTED;
    }
    logfd = system_fopenWA(fn);
    if(logfd == SYS_ERROR_FD) {
        pblock_nvinsert("error", "brief-init: please supply a file name", pb);
        return REQ_ABORTED;
    }
    /* Close log file when server is restarted */
    daemon_atrestart(brief_terminate, NULL);
    return REQ_PROCEED;
}

#ifdef __cplusplus
extern "C"
#endif
NSAPI_PUBLIC int brief_log(pblock *pb, Session *sn, Request *rq)
{
    /* No parameters */

    /* Server data */
    char *method = pblock_findval("method", rq->reqpb);
    char *uri = pblock_findval("uri", rq->reqpb);
    char *ip = pblock_findval("ip", sn->client);

    /* Temp vars */
    char *logmsg;
    int len;

    logmsg = (char *)
        MALLOC(strlen(ip) + 1 + strlen(method) + 1 + strlen(uri) + 1 + 1);
    len = util_sprintf(logmsg, "%s %s %s\n", ip, method, uri);
    /* The atomic version uses locking to prevent interference */
    system_fwrite_atomic(logfd, logmsg, len);
    FREE(logmsg);

    return REQ_PROCEED;
}