/*****************************************************************************
 * RRDtool 1.7.0, Copyright 1997-2017 by Tobi Oetiker
 *****************************************************************************
 * rrd_cgi.c  RRD Web Page Generator
 *****************************************************************************/

#include "rrd_tool.h"
#ifdef HAVE_STDLIB_H
#include <stdlib.h>
#endif

#define MEMBLK 1024
/*#define DEBUG_PARSER
#define DEBUG_VARS*/

typedef struct var_s {
    char     *name, *value;
} s_var;

typedef struct cgi_s {
    s_var   **vars;
} s_cgi;

/* in arg[0] find tags beginning with arg[1] call arg[2] on them
   and replace by result of arg[2] call */
static int parse(
    char **,
    long,
    char *,
    char *    (*)(long,
                  const char **));

/**************************************************/
/* tag replacers ... they are called from parse   */
/* through function pointers                      */
/**************************************************/

/* return cgi var named arg[0] */
static char *cgiget(
    long,
    const char **);

/* return a quoted cgi var named arg[0] */
static char *cgigetq(
    long,
    const char **);

/* return a quoted and sanitized cgi variable */
static char *cgigetqp(
    long,
    const char **);

/* call rrd_graph and insert appropriate image tag */
static char *drawgraph(
    long,
    const char **);

/* return PRINT functions from last rrd_graph call */
static char *drawprint(
    long,
    const char **);

/* pretty-print the <last></last> value for some.rrd via strftime() */
static char *printtimelast(
    long,
    const char **);

/* pretty-print current time */
static char *printtimenow(
    long,
    const char **);

/* set an environment variable */
static char *rrdsetenv(
    long,
    const char **);

/* get an environment variable */
static char *rrdgetenv(
    long,
    const char **);

/* include the named file at this point */
static char *includefile(
    long,
    const char **);

/* for how long is the output of the cgi valid ? */
static char *rrdgoodfor(
    long,
    const char **);

/* return rrdcgi version string */
static char *rrdgetinternal(
    long,
    const char **);

static char *rrdstrip(
    char *buf);
static char *scanargs(
    char *line,
    int *argc,
    char ***args);

/* format at-time specified times using strftime */
static char *printstrftime(
    long,
    const char **);

/** HTTP protocol needs special format, and GMT time **/
static char *http_time(
    time_t *);

/* return a pointer to newly allocated copy of this string */
static char *stralloc(
    const char *);

/* global variable for rrdcgi */
s_cgi    *rrdcgiArg;

/* rrdcgiDecodeString
 * decode html escapes
 */

static char *rrdcgiDecodeString(
    char *text);

/* rrdcgiDebug
 * 
 *  Set/unsets debugging
 */
static void rrdcgiDebug(
    int level,
    int where);

/* rrdcgiInit
 *
 *  Reads in variables set via POST or stdin.
 */
static s_cgi *rrdcgiInit(
    void);

/* rrdcgiGetValue
 *
 *  Returns the value of the specified variable or NULL if it's empty
 *  or doesn't exist.
 */
static char *rrdcgiGetValue(
    s_cgi * parms,
    const char *name);

/*  rrdcgiReadVariables()
 *
 *  Read from stdin if no string is provided via CGI.  Variables that
 *  doesn't have a value associated with it doesn't get stored.
 */
static s_var **rrdcgiReadVariables(
    void);


int       rrdcgiDebugLevel = 0;
int       rrdcgiDebugStderr = 1;
char     *rrdcgiHeaderString = NULL;
char     *rrdcgiType = NULL;

/* rrd interface to the variable functions {put,get}var() */
static char *rrdgetvar(
    long argc,
    const char **args);
static char *rrdsetvar(
    long argc,
    const char **args);
static char *rrdsetvarconst(
    long argc,
    const char **args);


/* variable store: put/get key-value pairs */
static int initvar(
    );
static void donevar(
    );
static const char *getvar(
    const char *varname);
static const char *putvar(
    const char *name,
    const char *value,
    int is_const);

/* key value pair that makes up an entry in the variable store */
typedef struct {
    int       is_const; /* const variable or not */
    const char *name;   /* variable name */
    const char *value;  /* variable value */
} vardata;

/* the variable heap: 
   start with a heapsize of 10 variables */
#define INIT_VARSTORE_SIZE	10
static vardata *varheap = NULL;
static size_t varheap_size = 0;

/* allocate and initialize variable heap */
static int initvar(
    void)
{
    varheap = (vardata *) malloc(sizeof(vardata) * INIT_VARSTORE_SIZE);
    if (varheap == NULL) {
        fprintf(stderr, "ERROR: unable to initialize variable store\n");
        return -1;
    }
    memset(varheap, 0, sizeof(vardata) * INIT_VARSTORE_SIZE);
    varheap_size = INIT_VARSTORE_SIZE;
    return 0;
}

/* cleanup: free allocated memory */
static void donevar(
    void)
{
    int       i;

    if (varheap) {
        for (i = 0; i < (int) varheap_size; i++) {
            if (varheap[i].name) {
                free((char *) varheap[i].name);
            }
            if (varheap[i].value) {
                free((char *) varheap[i].value);
            }
        }
        free(varheap);
    }
}

/* Get a variable from the variable store.
   Return NULL in case the requested variable was not found. */
static const char *getvar(
    const char *name)
{
    int       i;

    for (i = 0; i < (int) varheap_size && varheap[i].name; i++) {
        if (0 == strcmp(name, varheap[i].name)) {
#ifdef		DEBUG_VARS
            printf("<!-- getvar(%s) -> %s -->\n", name, varheap[i].value);
#endif
            return varheap[i].value;
        }
    }
#ifdef DEBUG_VARS
    printf("<!-- getvar(%s) -> Not found-->\n", name);
#endif
    return NULL;
}

/* Put a variable into the variable store. If a variable by that
   name exists, it's value is overwritten with the new value unless it was
   marked as 'const' (initialized by RRD::SETCONSTVAR).
   Returns a copy the newly allocated value on success, NULL on error. */
static const char *putvar(
    const char *name,
    const char *value,
    int is_const)
{
    int       i;

    for (i = 0; i < (int) varheap_size && varheap[i].name; i++) {
        if (0 == strcmp(name, varheap[i].name)) {
            /* overwrite existing entry */
            if (varheap[i].is_const) {
#ifdef	DEBUG_VARS
                printf("<!-- setver(%s, %s): not assigning: "
                       "const variable -->\n", name, value);
#endif
                return varheap[i].value;
            }
#ifdef	DEBUG_VARS
            printf("<!-- setvar(%s, %s): overwriting old value (%s) -->\n",
                   name, value, varheap[i].value);
#endif
            /* make it possible to promote a variable to readonly */
            varheap[i].is_const = is_const;
            free((char *) varheap[i].value);
            varheap[i].value = stralloc(value);
            return varheap[i].value;
        }
    }

    /* no existing variable found by that name, add it */
    if (i == (int) varheap_size) {
        /* ran out of heap: resize heap to double size */
        size_t    new_size = varheap_size * 2;

        varheap = (vardata *) (realloc(varheap, sizeof(vardata) * new_size));
        if (!varheap) {
            fprintf(stderr, "ERROR: Unable to realloc variable heap\n");
            return NULL;
        }
        /* initialize newly allocated memory */ ;
        memset(&varheap[varheap_size], 0, sizeof(vardata) * varheap_size);
        varheap_size = new_size;
    }
    varheap[i].is_const = is_const;
    varheap[i].name = stralloc(name);
    varheap[i].value = stralloc(value);

#ifdef		DEBUG_VARS
    printf("<!-- setvar(%s, %s): adding new variable -->\n", name, value);
#endif
    return varheap[i].value;
}

/* expand those RRD:* directives that can be used recursively */
static char *rrd_expand_vars(
    char *buffer)
{
    int       i;

#ifdef DEBUG_PARSER
    printf("expanding variables in '%s'\n", buffer);
#endif

    for (i = 0; buffer[i]; i++) {
        if (buffer[i] != '<')
            continue;
        parse(&buffer, i, "<RRD::CV", cgiget);
        parse(&buffer, i, "<RRD::CV::QUOTE", cgigetq);
        parse(&buffer, i, "<RRD::CV::PATH", cgigetqp);
        parse(&buffer, i, "<RRD::GETENV", rrdgetenv);
        parse(&buffer, i, "<RRD::GETVAR", rrdgetvar);
        parse(&buffer, i, "<RRD::TIME::LAST", printtimelast);
        parse(&buffer, i, "<RRD::TIME::NOW", printtimenow);
        parse(&buffer, i, "<RRD::TIME::STRFTIME", printstrftime);
        parse(&buffer, i, "<RRD::INTERNAL", rrdgetinternal);
    }
    return buffer;
}

static long goodfor = 0;
static char **calcpr = NULL;
static void calfree(
    void)
{
    if (calcpr) {
        long      i;

        for (i = 0; calcpr[i]; i++) {
            if (calcpr[i]) {
                free(calcpr[i]);
            }
        }
        if (calcpr) {
            free(calcpr);
        }
        calcpr = NULL;
    }
}

/* create freeable version of the string */
static char *stralloc(
    const char *str)
{
    if (!str) {
        return NULL;
    }
    return strdup(str);
}

static int readfile(
    const char *file_name,
    char **buffer,
    int skipfirst)
{
    long      writecnt = 0, totalcnt = MEMBLK;
    long      offset = 0;
    FILE     *input = NULL;
    char      c;

    if ((strcmp("-", file_name) == 0)) {
        input = stdin;
    } else {
        if ((input = fopen(file_name, "rb")) == NULL) {
            rrd_set_error("opening '%s': %s", file_name, rrd_strerror(errno));
            return (-1);
        }
    }
    if (skipfirst) {
        do {
            c = getc(input);
            offset++;
        } while (c != '\n' && !feof(input));
    }
    if (strcmp("-", file_name)) {
        fseek(input, 0, SEEK_END);
        /* have extra space for detecting EOF without realloc */
        totalcnt = (ftell(input) + 1) / sizeof(char) - offset;
        if (totalcnt < MEMBLK)
            totalcnt = MEMBLK;  /* sanitize */
        if (fseek(input, offset * sizeof(char), SEEK_SET) == -1)
        {
           rrd_set_error("fseek() failed on %s: %s", file_name, rrd_strerror(errno));
           fclose(input);
           return (-1);
        }
    }
    if (((*buffer) = (char *) malloc((totalcnt + 4) * sizeof(char))) == NULL) {
        perror("Allocate Buffer:");
        exit(1);
    };
    do {
        writecnt +=
            fread((*buffer) + writecnt, 1,
                  (totalcnt - writecnt) * sizeof(char), input);
        if (writecnt >= totalcnt) {
            totalcnt += MEMBLK;
            if (((*buffer) = (char *)
                 rrd_realloc((*buffer),
                             (totalcnt + 4) * sizeof(char))) == NULL) {
                perror("Realloc Buffer:");
                exit(1);
            };
        }
    } while (!feof(input));
    (*buffer)[writecnt] = '\0';
    if (strcmp("-", file_name) != 0) {
        fclose(input);
    };
    return writecnt;
}

int main(
    int argc,
    char *argv[])
{
    char     *buffer;
    long      i;
    long      filter = 0;
    struct optparse_long longopts[] = {
        {"filter", 'f', OPTPARSE_NONE},
        {0},
    };
    struct optparse options;
    int opt;

#ifdef MUST_DISABLE_SIGFPE
    signal(SIGFPE, SIG_IGN);
#endif
#ifdef MUST_DISABLE_FPMASK
    fpsetmask(0);
#endif

    /* what do we get for cmdline arguments?
       for (i=0;i<argc;i++)
       printf("%d-'%s'\n",i,argv[i]); */
    optparse_init(&options, argc, argv);
    while ((opt = optparse_long(&options,longopts,NULL)) != -1) {
        switch (opt) {
        case 'f':
            filter = 1;
            break;
        case '?':
            printf("%s\n", options.errmsg);
            return -1;
        }
    }

    if (!filter) {
        rrdcgiDebug(0, 0);
        rrdcgiArg = rrdcgiInit();
    }

    /* make sure we have one extra argument, 
       if there are others, we do not care Apache gives several */

    /* if ( (options.optind != options.argc-2 
       && strstr( getenv("SERVER_SOFTWARE"),"Apache/2") != NULL) 
       && options.optind != options.argc-1) { */

    if (options.optind >= options.argc) {
        fprintf(stderr, "ERROR: expected a filename\n");
        exit(1);
    } else {
        readfile(options.argv[options.optind], &buffer, 1);
    }

    if (rrd_test_error()) {
        fprintf(stderr, "ERROR: %s\n", rrd_get_error());
        exit(1);
    }

    /* initialize variable heap */
    initvar();

#ifdef DEBUG_PARSER
    /* some fake header for testing */
    printf("Content-Type: text/html\nContent-Length: 10000000\n\n\n");
#endif


    /* expand rrd directives in buffer recursivley */
    for (i = 0; buffer[i]; i++) {
        if (buffer[i] != '<')
            continue;
        if (!filter) {
            parse(&buffer, i, "<RRD::CV", cgiget);
            parse(&buffer, i, "<RRD::CV::PATH", cgigetqp);
            parse(&buffer, i, "<RRD::CV::QUOTE", cgigetq);
            parse(&buffer, i, "<RRD::GETENV", rrdgetenv);
        }
        parse(&buffer, i, "<RRD::GETVAR", rrdgetvar);
        parse(&buffer, i, "<RRD::GOODFOR", rrdgoodfor);
        parse(&buffer, i, "<RRD::GRAPH", drawgraph);
        parse(&buffer, i, "<RRD::INCLUDE", includefile);
        parse(&buffer, i, "<RRD::PRINT", drawprint);
        parse(&buffer, i, "<RRD::SETCONSTVAR", rrdsetvarconst);
        parse(&buffer, i, "<RRD::SETENV", rrdsetenv);
        parse(&buffer, i, "<RRD::SETVAR", rrdsetvar);
        parse(&buffer, i, "<RRD::TIME::LAST", printtimelast);
        parse(&buffer, i, "<RRD::TIME::NOW", printtimenow);
        parse(&buffer, i, "<RRD::TIME::STRFTIME", printstrftime);
        parse(&buffer, i, "<RRD::INTERNAL", rrdgetinternal);
    }

    if (!filter) {
        printf("Content-Type: text/html\n"
               "Content-Length: %zd\n", strlen(buffer));

        if (labs(goodfor) > 0) {
            time_t    now;

            now = time(NULL);
            printf("Last-Modified: %s\n", http_time(&now));
            now += labs(goodfor);
            printf("Expires: %s\n", http_time(&now));
            if (goodfor < 0) {
                printf("Refresh: %ld\n", labs(goodfor));
            }
        }
        printf("\n");
    }

    /* output result */
    printf("%s", buffer);

    /* cleanup */
    calfree();
    if (buffer) {
        free(buffer);
    }
    donevar();
    exit(0);
}

/* remove occurrences of .. this is a general measure to make
   paths which came in via cgi do not go UP ... */

static char *rrdsetenv(
    long argc,
    const char **args)
{
    if (argc >= 2) {
        const size_t len = strlen(args[0]) + strlen(args[1]) + 2;
        char *xyz = (char *) malloc(len);

        if (xyz == NULL) {
            return stralloc("[ERROR: allocating setenv buffer]");
        };
        snprintf(xyz, len, "%s=%s", args[0], args[1]);
        if (putenv(xyz) == -1) {
            free(xyz);
            return stralloc("[ERROR: failed to do putenv]");
        };
        return stralloc("");
    }
    return stralloc("[ERROR: setenv failed because not enough "
                    "arguments were defined]");
}

/* rrd interface to the variable function putvar() */
static char *rrdsetvar(
    long argc,
    const char **args)
{
    if (argc >= 2) {
        const char *result = putvar(args[0], args[1], 0 /* not const */ );

        if (result) {
            /* setvar does not return the value set */
            return stralloc("");
        }
        return stralloc("[ERROR: putvar failed]");
    }
    return stralloc("[ERROR: putvar failed because not enough arguments "
                    "were defined]");
}

/* rrd interface to the variable function putvar() */
static char *rrdsetvarconst(
    long argc,
    const char **args)
{
    if (argc >= 2) {
        const char *result = putvar(args[0], args[1], 1 /* const */ );

        if (result) {
            /* setvar does not return the value set */
            return stralloc("");
        }
        return stralloc("[ERROR: putvar failed]");
    }
    return stralloc("[ERROR: putvar failed because not enough arguments "
                    "were defined]");
}

static char *rrdgetenv(
    long argc,
    const char **args)
{
    char      buf[128];
    const char *envvar;

    if (argc != 1) {
        return stralloc("[ERROR: getenv failed because it did not "
                        "get 1 argument only]");
    };
    envvar = getenv(args[0]);
    if (envvar) {
        return stralloc(envvar);
    } else {
        snprintf(buf, sizeof(buf), "[ERROR:_getenv_'%s'_failed", args[0]);
        return stralloc(buf);
    }
}

static char *rrdgetvar(
    long argc,
    const char **args)
{
    char      buf[128];
    const char *value;

    if (argc != 1) {
        return stralloc("[ERROR: getvar failed because it did not "
                        "get 1 argument only]");
    };
    value = getvar(args[0]);
    if (value) {
        return stralloc(value);
    } else {
        snprintf(buf, sizeof(buf), "[ERROR:_getvar_'%s'_failed", args[0]);
        return stralloc(buf);
    }
}

static char *rrdgoodfor(
    long argc,
    const char **args)
{
    if (argc == 1) {
        goodfor = atol(args[0]);
    } else {
        return stralloc("[ERROR: goodfor expected 1 argument]");
    }

    if (goodfor == 0) {
        return stralloc("[ERROR: goodfor value must not be 0]");
    }

    return stralloc("");
}

static char *rrdgetinternal(
    long argc,
    const char **args)
{
    if (argc == 1) {
        if (strcasecmp(args[0], "VERSION") == 0) {
            return stralloc(PACKAGE_VERSION);
        } else if (strcasecmp(args[0], "COMPILETIME") == 0) {
            return stralloc(__DATE__ " " __TIME__);
        } else {
            return stralloc("[ERROR: internal unknown argument]");
        }
    } else {
        return stralloc("[ERROR: internal expected 1 argument]");
    }
}

/* Format start or end times using strftime.  We always need both the
 * start and end times, because, either might be relative to the other.
 * */
#define MAX_STRFTIME_SIZE 256
static char *printstrftime(
    long argc,
    const char **args)
{
    rrd_time_value_t start_tv, end_tv;
    char     *parsetime_error = NULL;
    char      formatted[MAX_STRFTIME_SIZE];
    struct tm *the_tm;
    time_t    start_tmp, end_tmp;

    /* Make sure that we were given the right number of args */
    if (argc != 4) {
        rrd_set_error("wrong number of args %d", argc);
        return stralloc("");
    }

    /* Init start and end time */
    rrd_parsetime("end-24h", &start_tv);
    rrd_parsetime("now", &end_tv);

    /* Parse the start and end times we were given */
    if ((parsetime_error = rrd_parsetime(args[1], &start_tv))) {
        rrd_set_error("start time: %s", parsetime_error);
        return stralloc("");
    }
    if ((parsetime_error = rrd_parsetime(args[2], &end_tv))) {
        rrd_set_error("end time: %s", parsetime_error);
        return stralloc("");
    }
    if (rrd_proc_start_end(&start_tv, &end_tv, &start_tmp, &end_tmp) == -1) {
        return stralloc("");
    }

    /* Do we do the start or end */
    if (strcasecmp(args[0], "START") == 0) {
        the_tm = localtime(&start_tmp);
    } else if (strcasecmp(args[0], "END") == 0) {
        the_tm = localtime(&end_tmp);
    } else {
        rrd_set_error("start/end not found in '%s'", args[0]);
        return stralloc("");
    }

    /* now format it */
    if (strftime(formatted, MAX_STRFTIME_SIZE, args[3], the_tm)) {
        return (stralloc(formatted));
    } else {
        rrd_set_error("strftime failed");
        return stralloc("");
    }
}

static char *includefile(
    long argc,
    const char **args)
{
    char     *buffer;

    if (argc >= 1) {
        const char *filename = args[0];

        readfile(filename, &buffer, 0);
        if (rrd_test_error()) {
            const size_t len = strlen(rrd_get_error()) + DS_NAM_SIZE;
            char *err = (char *) malloc(len);

            snprintf(err, len, "[ERROR: %s]", rrd_get_error());
            rrd_clear_error();
            free(buffer);
            return err;
        } else {
            return buffer;
        }
    } else {
        return stralloc("[ERROR: No Include file defined]");
    }
}

/* make a copy of buf and replace open/close brackets with '_' */
static char *rrdstrip(
    char *buf)
{
    char     *p;

    if (buf == NULL) {
        return NULL;
    }
    /* make a copy of the buffer */
    buf = stralloc(buf);
    if (buf == NULL) {
        return NULL;
    }

    p = buf;
    while (*p) {
        if (*p == '<' || *p == '>') {
            *p = '_';
        }
        p++;
    }
    return buf;
}

static char *cgigetq(
    long argc,
    const char **args)
{
    if (argc >= 1) {
        char     *buf = rrdstrip(rrdcgiGetValue(rrdcgiArg, args[0]));
        char     *buf2;
        char     *c, *d;
        int       qc = 0;

        if (buf == NULL)
            return NULL;

        for (c = buf; *c != '\0'; c++)
            if (*c == '"')
                qc++;
        if ((buf2 = (char *) malloc((strlen(buf) + 4 * qc + 4))) == NULL) {
            perror("Malloc Buffer");
            exit(1);
        };
        c = buf;
        d = buf2;
        *(d++) = '"';
        while (*c != '\0') {
            if (*c == '"') {
                *(d++) = '"';
                *(d++) = '\'';
                *(d++) = '"';
                *(d++) = '\'';
            }
            *(d++) = *(c++);
        }
        *(d++) = '"';
        *(d) = '\0';
        free(buf);
        return buf2;
    }

    return stralloc("[ERROR: not enough argument for RRD::CV::QUOTE]");
}

/* remove occurrences of .. this is a general measure to make
   paths which came in via cgi do not go UP ... */

static char *cgigetqp(
    long argc,
    const char **args)
{
    char     *buf;
    char     *buf2;
    char     *p;
    char     *d;

    if (argc < 1) {
        return stralloc("[ERROR: not enough arguments for RRD::CV::PATH]");
    }

    buf = rrdstrip(rrdcgiGetValue(rrdcgiArg, args[0]));
    if (!buf) {
        return NULL;
    }

    buf2 = (char *) malloc(strlen(buf) + 1);
    if (!buf2) {
        perror("cgigetqp(): Malloc Path Buffer");
        exit(1);
    };

    p = buf;
    d = buf2;

    while (*p) {
        /* prevent mallicious paths from entering the system */
        if (p[0] == '.' && p[1] == '.') {
            p += 2;
            *d++ = '_';
            *d++ = '_';
        } else {
            *d++ = *p++;
        }
    }

    *d = 0;
    free(buf);

    /* Make sure the path is relative, e.g. does not start with '/' */
    p = buf2;
    while ('/' == *p) {
        *p++ = '_';
    }

    return buf2;
}


static char *cgiget(
    long argc,
    const char **args)
{
    if (argc >= 1)
        return rrdstrip(rrdcgiGetValue(rrdcgiArg, args[0]));
    else
        return stralloc("[ERROR: not enough arguments for RRD::CV]");
}



static char *drawgraph(
    long argc,
    const char **args)
{
    int       i, xsize, ysize;
    double    ymin, ymax;

    for (i = 0; i < argc; i++)
        if (strcmp(args[i], "--imginfo") == 0 || strcmp(args[i], "-g") == 0)
            break;
    if (i == argc) {
        args[argc++] = "--imginfo";
        args[argc++] = "<IMG SRC=\"./%s\" WIDTH=\"%lu\" HEIGHT=\"%lu\">";
    }
    calfree();
    if (rrd_graph
        (argc + 1, (char **) args - 1, &calcpr, &xsize, &ysize, NULL, &ymin,
         &ymax) != -1) {
        return stralloc(calcpr[0]);
    } else {
        if (rrd_test_error()) {
            const size_t len = strlen(rrd_get_error()) + DS_NAM_SIZE;
            char *err = (char *) malloc(len);
            snprintf(err, len, "[ERROR: %s]", rrd_get_error());
            rrd_clear_error();
            return err;
        }
    }
    return NULL;
}

static char *drawprint(
    long argc,
    const char **args)
{
    if (argc == 1 && calcpr) {
        long      i = 0;

        while (calcpr[i] != NULL)
            i++;        /*determine number lines in calcpr */
        if (atol(args[0]) < i - 1)
            return stralloc(calcpr[atol(args[0]) + 1]);
    }
    return stralloc("[ERROR: RRD::PRINT argument error]");
}

static char *printtimelast(
    long argc,
    const char **args)
{
    time_t    last;
    struct tm tm_last;
    char     *buf;

    if (argc == 2) {
        buf = (char *) malloc(255);
        if (buf == NULL) {
            return stralloc("[ERROR: allocating strftime buffer]");
        };
        /* not raising argc in step with args - 1 since the last argument
           will be used below for strftime  */

        last = rrd_last(argc, (char **) args - 1);
        if (rrd_test_error()) {
            const size_t len = strlen(rrd_get_error()) + DS_NAM_SIZE;
            char *err = (char *) malloc(len);
            snprintf(err, len, "[ERROR: %s]", rrd_get_error());
            rrd_clear_error();
            free(buf);
            return err;
        }
        tm_last = *localtime(&last);
        strftime(buf, 254, args[1], &tm_last);
        return buf;
    }
    return stralloc("[ERROR: expected <RRD::TIME::LAST file.rrd strftime-format>]");
}

static char *printtimenow(
    long argc,
    const char **args)
{
    time_t    now = time(NULL);
    struct tm tm_now;
    char     *buf;

    if (argc == 1) {
        buf = (char *) malloc(255);
        if (buf == NULL) {
            return stralloc("[ERROR: allocating strftime buffer]");
        };
        tm_now = *localtime(&now);
        strftime(buf, 254, args[0], &tm_now);
        return buf;
    }
    if (argc < 1) {
        return stralloc("[ERROR: too few arguments for RRD::TIME::NOW]");
    }
    return stralloc("[ERROR: not enough arguments for RRD::TIME::NOW]");
}

/* Scan buffer until an unescaped '>' arrives.
 * Update argument array with arguments found.
 * Return end cursor where parsing stopped, or NULL in case of failure.
 *
 * FIXME:
 * To allow nested constructs, we call rrd_expand_vars() for arguments
 * that contain RRD::x directives. These introduce a small memory leak
 * since we have to stralloc the arguments the way parse() works.
 */
static char *scanargs(
    char *line,
    int *argument_count,
    char ***arguments)
{
    char     *getP;     /* read cursor */
    char     *putP;     /* write cursor */
    char      Quote;    /* type of quote if in quoted string, 0 otherwise */
    int       tagcount; /* open tag count */
    int       in_arg;   /* if we currently are parsing an argument or not */
    int       argsz;    /* argument array size */
    int       curarg_contains_rrd_directives;

    /* local array of arguments while parsing */
    int       argc = 1;
    char    **argv;

#ifdef DEBUG_PARSER
    printf("<-- scanargs(%s) -->\n", line);
#endif

    *arguments = NULL;
    *argument_count = 0;

    /* create initial argument array of char pointers */
    argsz = 32;
    argv = (char **) malloc(argsz * sizeof(char *));
    if (!argv) {
        return NULL;
    }
    argv[0] = "rrdcgi";

    /* skip leading blanks */
    while (isspace((int) *line)) {
        line++;
    }

    getP = line;
    putP = line;

    Quote = 0;
    in_arg = 0;
    tagcount = 0;

    curarg_contains_rrd_directives = 0;

    /* start parsing 'line' for arguments */
    while (*getP) {
        unsigned char c = *getP++;

        if (c == '>' && !Quote && !tagcount) {
            /* this is our closing tag, quit scanning */
            break;
        }

        /* remove all special chars */
        if (c < ' ') {
            c = ' ';
        }

        switch (c) {
        case ' ':
            if (Quote || tagcount) {
                /* copy quoted/tagged (=RRD expanded) string */
                *putP++ = c;
            } else if (in_arg) {
                /* end argument string */
                *putP++ = 0;
                in_arg = 0;
                if (curarg_contains_rrd_directives) {
                    argv[argc - 1] =
                        rrd_expand_vars(stralloc(argv[argc - 1]));
                    curarg_contains_rrd_directives = 0;
                }
            }
            break;

        case '"':      /* Fall through */
        case '\'':
            if (Quote != 0) {
                if (Quote == c) {
                    Quote = 0;
                } else {
                    /* copy quoted string */
                    *putP++ = c;
                }
            } else {
                if (!in_arg) {
                    /* reference start of argument string in argument array */
                    argv[argc++] = putP;
                    in_arg = 1;
                }
                Quote = c;
            }
            break;

        default:
            if (!in_arg) {
                /* start new argument */
                argv[argc++] = putP;
                in_arg = 1;
            }
            if (c == '>') {
                if (tagcount) {
                    tagcount--;
                }
            }
            if (c == '<') {
                tagcount++;
                if (0 == strncmp(getP, "RRD::", strlen("RRD::"))) {
                    curarg_contains_rrd_directives = 1;
                }
            }
            *putP++ = c;
            break;
        }

        /* check if our argument array is still large enough */
        if (argc == argsz - 2) {
            /* resize argument array */
            argsz *= 2;
            argv = (char **) rrd_realloc(argv, argsz * sizeof(char *));
            if (*argv == NULL) {
                return NULL;
            }
        }
    }

    /* terminate last argument found */
    *putP = '\0';
    if (curarg_contains_rrd_directives) {
        argv[argc - 1] = rrd_expand_vars(stralloc(argv[argc - 1]));
    }
#ifdef DEBUG_PARSER
    if (argc > 1) {
        int       n;

        printf("<-- arguments found [%d]\n", argc);
        for (n = 0; n < argc; n++) {
            printf("arg %02d: '%s'\n", n, argv[n]);
        }
        printf("-->\n");
    } else {
        printf("<!-- No arguments found -->\n");
    }
#endif

    /* update caller's notion of the argument array and it's size */

    /* note this is a bit of a hack since the rrd_cgi code used to just put
       its arguments into a normal array starting at 0 ... since the rrd_*
       commands expect and argc/argv array we used to just shift everything
       by -1 ... this in turn exploded when a rrd_* function tried to print
       argv[0] ... hence we are now doing everything in argv style but hand
       over seemingly the old array ... but doing argv-1 will actually end
       up in a 'good' place now. */

    *arguments = argv+1;
    *argument_count = argc-1;

    if (Quote) {
        return NULL;
    }

    /* Return new scanning cursor:
       pointer to char after closing bracket */
    return getP;
}


/*
 * Parse(): scan current portion of buffer for given tag.
 * If found, parse tag arguments and call 'func' for it.
 * The result of func is inserted at the current position
 * in the buffer.
 */
static int parse(
    char **buf,         /* buffer */
    long i,             /* offset in buffer */
    char *tag,          /* tag to handle  */
    char *    (*func) (long,
                       const char **)   /* function to call for 'tag' */
    )
{
    /* the name of the vairable ... */
    char     *val;
    long      valln;
    char    **args;
    char     *end;
    long      end_offset;
    int       argc;
    size_t    taglen = strlen(tag);

    /* Current position in buffer should start with 'tag' */
    if (strncmp((*buf) + i, tag, taglen) != 0) {
        return 0;
    }
    /* .. and match exactly (a whitespace following 'tag') */
    if (!isspace(*((*buf) + i + taglen))) {
        return 0;
    }
#ifdef DEBUG_PARSER
    printf("parse(): handling tag '%s'\n", tag);
#endif

    /* Scan for arguments following the tag;
       scanargs() puts \0 into *buf ... so after scanargs it is probably
       not a good time to use strlen on buf */
    end = scanargs((*buf) + i + taglen, &argc, &args);
    if (end) {
        /* got arguments, call function for 'tag' with arguments */
        val = func(argc, (const char **) args);
        free(args-1);
    } else {
        /* next call, try parsing at current offset +1 */
        end = (*buf) + i + 1;

        val = stralloc("[ERROR: Parsing Problem with the following text\n"
                       " Check original file. This may have been altered "
                       "by parsing.]\n\n");
    }

    /* remember offset where we have to continue parsing */
    end_offset = end - (*buf);

    valln = 0;
    if (val) {
        valln = strlen(val);
    }

    /* Optionally resize buffer to hold the replacement value:
       Calculating the new length of the buffer is simple. add current
       buffer pos (i) to length of string after replaced tag to length
       of replacement string and add 1 for the final zero ... */
    if (end - (*buf) < (i + valln)) {
        /* make sure we do not shrink the mallocd block */
        size_t    newbufsize = i + strlen(end) + valln + 1;

        *buf = (char *) rrd_realloc(*buf, newbufsize);

        if (*buf == NULL) {
            perror("Realoc buf:");
            exit(1);
        };
    }

    /* Update new end pointer:
       make sure the 'end' pointer gets moved along with the 
       buf pointer when realloc moves memory ... */
    end = (*buf) + end_offset;

    /* splice the variable:
       step 1. Shift pending data to make room for 'val' */
    memmove((*buf) + i + valln, end, strlen(end) + 1);

    /* step 2. Insert val */
    if (val) {
        memmove((*buf) + i, val, valln);
        free(val);
    }
    return (valln > 0 ? valln - 1 : valln);
}

static char *http_time(
    time_t *now)
{
    struct tm *tmptime;
    static char buf[60];

    tmptime = gmtime(now);
    strftime(buf, sizeof(buf), "%a, %d %b %Y %H:%M:%S GMT", tmptime);
    return (buf);
}

static void rrdcgiDebug(
    int level,
    int where)
{
    if (level > 0)
        rrdcgiDebugLevel = level;
    else
        rrdcgiDebugLevel = 0;
    if (where)
        rrdcgiDebugStderr = 0;
    else
        rrdcgiDebugStderr = 1;
}

static char *rrdcgiDecodeString(
    char *text)
{
    char     *cp, *xp;

    for (cp = text, xp = text; *cp; cp++) {
        if (*cp == '%') {
            if (strchr("0123456789ABCDEFabcdef", *(cp + 1))
                && strchr("0123456789ABCDEFabcdef", *(cp + 2))) {
                if (islower(*(cp + 1)))
                    *(cp + 1) = toupper(*(cp + 1));
                if (islower(*(cp + 2)))
                    *(cp + 2) = toupper(*(cp + 2));
                *(xp) =
                    (*(cp + 1) >=
                     'A' ? *(cp + 1) - 'A' + 10 : *(cp + 1) - '0') * 16 +
                    (*(cp + 2) >=
                     'A' ? *(cp + 2) - 'A' + 10 : *(cp + 2) - '0');
                xp++;
                cp += 2;
            }
        } else {
            *(xp++) = *cp;
        }
    }
    memset(xp, 0, cp - xp);
    return text;
}

/* free_result(s_var**, number)
 *
 * Clean-up the 'result' variable from rrdcgiReadVariables() properly.
 * We can safely call free() on result[i]->{name,value} because they are
 * memset() to 0 after their allocation.
 */
static void free_result(s_var **result, int number)
{
    int i;

    for(i = 0; i < number; i++) {
        if (result && result[i]) {
            free(result[i]->name);
            free(result[i]->value);
            free(result[i]);
        }
    }
    free(result);
}

/*  rrdcgiReadVariables()
 *
 *  Read from stdin if no string is provided via CGI.  Variables that
 *  doesn't have a value associated with it doesn't get stored.
 */
static s_var **rrdcgiReadVariables(
    void)
{
    int       length;
    char     *line = NULL;
    int       numargs;
    char     *cp, *ip, *esp, *sptr;
    s_var   **result;
    int       i, k, len;
    char      tmp[101];
    size_t    tmplen;

    cp = getenv("REQUEST_METHOD");
    ip = getenv("CONTENT_LENGTH");

    if (cp && !strcmp(cp, "POST")) {
        if (ip) {
            length = atoi(ip);
            if ((line = (char *) malloc(length + 2)) == NULL)
                return NULL;
            if (fgets(line, length + 1, stdin) == NULL) {
                free(line);
                return NULL;
            }
        } else
            return NULL;
    } else if (cp && !strcmp(cp, "GET")) {
        esp = getenv("QUERY_STRING");
        if (esp && strlen(esp)) {
            if ((line = strdup(esp)) == NULL)
                return NULL;
        } else
            return NULL;
    } else {
        length = 0;
        printf("(offline mode: enter name=value pairs on standard input)\n");
        memset(tmp, 0, sizeof(tmp));
        while ((cp = fgets(tmp, 100, stdin)) != NULL) {
            if ((tmplen = strlen(tmp)) != 0) {
                if (tmp[tmplen - 1] == '\n')
                    tmp[tmplen - 1] = '&';
                length += tmplen;
                len = (length + 1) * sizeof(char);
                if ((unsigned) length > tmplen) {
                    if ((line = (char *) realloc(line, len)) == NULL)
                        return NULL;
                    strncat(line, tmp, tmplen);
                } else {
                    /* clean-up the storage allocated in previous iteration */
                    if (line) {
                        free(line);
                    }

                    if ((line = strdup(tmp)) == NULL)
                        return NULL;
                }
            }
            memset(tmp, 0, sizeof(tmp));
        }
        if (!line) {
            return NULL;
        }
        if (line[strlen(line) - 1] == '&')
            line[strlen(line) - 1] = '\0';
    }

    /*
     *  From now on all cgi variables are stored in the variable line
     *  and look like  foo=bar&foobar=barfoo&foofoo=
     */

    if (rrdcgiDebugLevel > 0) {
        if (rrdcgiDebugStderr)
            fprintf(stderr, "Received cgi input: %s\n", line);
        else
            printf
                ("<b>Received cgi input</b><br>\n<pre>\n--\n%s\n--\n</pre>\n\n",
                 line);
    }

    for (cp = line; *cp; cp++)
        if (*cp == '+')
            *cp = ' ';

    if (strlen(line)) {
        for (numargs = 1, cp = line; *cp; cp++)
            if (*cp == '&')
                numargs++;
    } else
        numargs = 0;
    if (rrdcgiDebugLevel > 0) {
        if (rrdcgiDebugStderr)
            fprintf(stderr, "%d cgi variables found.\n", numargs);
        else
            printf("%d cgi variables found.<br>\n", numargs);
    }

    len = (numargs + 1) * sizeof(s_var *);
    if ((result = (s_var **) malloc(len)) == NULL) {
        free(line);
        return NULL;
    }
    memset(result, 0, len);

    cp = line;
    i = 0;
    while (*cp) {
        if ((ip = (char *) strchr(cp, '&')) != NULL) {
            *ip = '\0';
        } else
            ip = cp + strlen(cp);

        if ((esp = (char *) strchr(cp, '=')) == NULL) {
            cp = ++ip;
            continue;
        }

        if (!strlen(esp)) {
            cp = ++ip;
            continue;
        }

        if (i < numargs) {

            /* try to find out if there's already such a variable */
            for (k = 0; k < i && (strncmp(result[k]->name, cp, esp - cp)
                                  || !(strlen(result[k]->name) ==
                                       (size_t) (esp - cp))); k++);

            if (k == i) {   /* No such variable yet */
                if ((result[i] = (s_var *) malloc(sizeof(s_var))) == NULL) {
                    free_result(result, i);
                    free(line);
                    return NULL;
                }
                if ((result[i]->name =
                     (char *) malloc((esp - cp + 1) * sizeof(char))) == NULL) {
                    free_result(result, i);
                    free(line);
                    return NULL;
                }
                memset(result[i]->name, 0, esp - cp + 1);
                strncpy(result[i]->name, cp, esp - cp);
                cp = ++esp;
                if ((result[i]->value =
                     (char *) malloc((ip - esp + 1) * sizeof(char))) == NULL) {
                    free_result(result, i);
                    free(line);
                    return NULL;
                }
                memset(result[i]->value, 0, ip - esp + 1);
                strncpy(result[i]->value, cp, ip - esp);
                result[i]->value = rrdcgiDecodeString(result[i]->value);
                if (rrdcgiDebugLevel) {
                    if (rrdcgiDebugStderr)
                        fprintf(stderr, "%s: %s\n", result[i]->name,
                                result[i]->value);
                    else
                        printf("<h3>Variable %s</h3>\n<pre>\n%s\n</pre>\n\n",
                               result[i]->name, result[i]->value);
                }
                i++;
            } else {    /* There is already such a name, suppose a multiple field */
                cp = ++esp;
                len = strlen(result[k]->value) + (ip - esp) + 2;
                if ((sptr = (char *) calloc(len, sizeof(char))) == NULL) {
                    free_result(result, i);
                    free(line);
                    return NULL;
                }
                snprintf(sptr, len, "%s\n%s", result[k]->value, cp);
                free(result[k]->value);
                result[k]->value = rrdcgiDecodeString(sptr);
            }
        }
        cp = ++ip;
    }

    free(line);
    return result;
}

/*  rrdcgiInit()
 *
 *  Read from stdin if no string is provided via CGI.  Variables that
 *  doesn't have a value associated with it doesn't get stored.
 */
static s_cgi *rrdcgiInit(
    void)
{
    s_cgi    *res;
    s_var   **vars;

    if ((res = (s_cgi *) malloc(sizeof(s_cgi))) == NULL) {
        return NULL;
    }

    vars = rrdcgiReadVariables();

    if (!vars) {
    	free(res);
        return NULL;
    }

    res->vars = vars;

    return res;
}

static char *rrdcgiGetValue(
    s_cgi * parms,
    const char *name)
{
    int       i;

    if (!parms || !parms->vars)
        return NULL;
    for (i = 0; parms->vars[i]; i++)
        if (!strcmp(name, parms->vars[i]->name)) {
            if (rrdcgiDebugLevel > 0) {
                if (rrdcgiDebugStderr)
                    fprintf(stderr, "%s found as %s\n", name,
                            parms->vars[i]->value);
                else
                    printf("%s found as %s<br>\n", name,
                           parms->vars[i]->value);
            }
            return parms->vars[i]->value;
        }
    if (rrdcgiDebugLevel) {
        if (rrdcgiDebugStderr)
            fprintf(stderr, "%s not found\n", name);
        else
            printf("%s not found<br>\n", name);
    }
    return NULL;
}

