/*
 * Sendhercules
 *
 * This program connects to the HTTP server port of a local or remote Hercules
 * instance and uses HTTP POST to send a Hercules command to it for execution.
 * The HTTP response sent back by Hercules is discarded.
 *
 * Copyright 2014 Peter Coghlan.
 *
 * See http://software.beyondthepale.ie/hercules/sendhercules/license.txt
 * for terms of use.
 *
 * Some inspiration and code from fetch_http in the OSU webserver by
 * David Jones, Ohio State University
 *
 * 16-Aug-2014 V1.0 Initial version
 * 11-Sep-2014 V1.1 Added #include <unistd.h> to pick up close. (Thanks Enrico!)
 *
 * Please send bug reports and suggestions by email to:
 *                                        software at beyondthepale dot ie
 *
 * Usage:
 *
 *      sendhercules address:port command
 *   
 * Arguments:
 *
 *	address:port	Domain name or ip address and HTTP port number of
 *                      Hercules instance to send command to.
 *
 *      command         Command to send.
 *
 */

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include <unistd.h>
#include <sys/uio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <errno.h>
#include <netdb.h>

/* The following constants must be changed if they are changed in Hercules */

#define PATH "/cgi-bin/tasks/syslog"
#define PREFIX "command="

void main ( int argc, char **argv )
{
    int i, status, sd, port;
    void urlencode();
    struct sockaddr local, remote;
    struct hostent *hostinfo;
    char *arguments, *command, *host, *hostandport, *request;

    /* Are there enough arguments to proceed? */

    if (argc < 3) {
	fprintf(stderr,"\nUsage:\n\n"
        "   sendhercules address:port command\n\n"
        "   Where address:port specifies the domain name or TCP/IP network\n"
        "   address and HTTP server port of the Hercules instance to send\n"
        "   the command to.\n\n");
	exit(EXIT_SUCCESS);
    }

    /* First argument is the address and port of the Hercules instance */

    hostandport = argv[1];

    /* Subsequent arguments comprise the command to be sent.  If there is
       more than one more argument, contatenate them with spaces between.  */

    arguments = NULL;

    for ( i = 2; i < argc; i++ ) {
        int length;

        if (arguments == NULL) length = 0;
        else length = strlen(arguments) + 1;

        arguments = realloc(arguments,
                              (length + strlen(argv[i]) + 1) * sizeof(char));

        if (arguments == NULL) {
            fprintf(stderr, "Cannot allocate memory for argument %d\n", i);
            exit(EXIT_FAILURE);
        }

        if (i == 2) arguments[0] = '\0';
        else strcat(arguments, " ");

        strcat(arguments, argv[i]);
    }

    /* Allocate enough memory for the maximum possible length of the
       urlencoded command                                               */

    command = malloc(strlen(arguments) * sizeof(char) * 3 + 1);

    if (command == NULL) {
        free(arguments);
        fprintf(stderr, "Cannot allocate memory for command string\n");
        exit(EXIT_FAILURE);
    }

    /* Encode the command for transmission as a URL */

    urlencode(command, arguments);

    /* Free up the original string which is no longer required */

    free(arguments);

    /* Make a copy of the host and port string */

    host = strdup(hostandport);

    /*
     * Remove the port specification leaving just the name of the remote host
     * Save the port number separately as an integer
     */

    port = 80;   /* Default to port 80 if port is not specified */

    for (i = 0; host[i]; i++) if (host[i] == ':') {
	port = atoi(&host[i+1]);
        if ((port <= 0) || (port > 65535)) {
            fprintf(stderr,"Port %s is not valid", &host[i+1]);
            free(command);
            exit(EXIT_FAILURE);
        }
	host[i] = '\0';
	break;
    }

    /*
     * Create socket on first available port.
     */
    sd = socket ( AF_INET, SOCK_STREAM, 0 );
    if ( sd < 0 ) {
	    fprintf(stderr,"Error creating socket: %s\n", strerror(errno) );
            free(command);
            exit(EXIT_FAILURE);
    }
    local.sa_family = AF_INET;
    for ( i = 0; i < sizeof(local.sa_data); i++ ) local.sa_data[i] = '\0';
    status = bind ( sd, &local, sizeof ( local ) );
    if ( status < 0 ) {
	    fprintf(stderr,"Error binding socket: %s\n", strerror(errno) );
            free(command);
            close(sd);
            exit(EXIT_FAILURE);
    }
    /*
     * Lookup host.
     */
    hostinfo = gethostbyname ( host );
    if ( !hostinfo ) {
	fprintf(stderr, "Could not find resolve address '%s'\n", host );
        free(command);
        close(sd);
	exit(EXIT_FAILURE);
    }
    remote.sa_family = hostinfo->h_addrtype;
    for ( i = 0; i < hostinfo->h_length; i++ ) {
	    remote.sa_data[i+2] = hostinfo->h_addr_list[0][i];
    }

    remote.sa_data[0] = port >> 8;
    remote.sa_data[1] = port & 255;

    /*
     * Connect to remote host.
     */

    status = connect ( sd, &remote, sizeof(remote) );
    if ( status == 0 ) {
	int length;

        /* Build POST request */

        length = strlen(PREFIX) + strlen(command);

        request = malloc(
            (length + strlen(hostandport) + strlen(PATH) + 256) * sizeof(char));

        if (request == NULL) {
            fprintf(stderr, "Cannot allocate memory for POST request\n");
            free(command);
            close(sd);
            exit(EXIT_FAILURE);
        }
                                          
        sprintf ( request,
            "POST %s HTTP/1.0\r\n"
            "Host: %s\r\n"
            "Content-Type: application/x-www-form-urlencoded\r\n"
            "Content-Length: %d\r\n"
            "\r\n"
            PREFIX "%s",
            PATH, hostandport, length, command );

        free(command);

	status = send ( sd, request, strlen(request), 0 );
	if ( status < 0 ) {
            fprintf(stderr,"Error sending command to '%s': %s\n",
                hostandport, strerror(errno) );
            free(request);
            close(sd);
            exit(EXIT_FAILURE);
        }

        free(request);

    }
    else {
        fprintf(stderr, "Error connecting to '%s': %s\n",
                             hostandport, strerror(errno) );
        close(sd);
        exit(EXIT_FAILURE);
    }

    close ( sd );

    exit(EXIT_SUCCESS);
}

/*  Encode a string for transmission as a URL */

void urlencode(char *output, char *input)
{
    int i, j;

    for (i = j = 0; i < strlen(input); i++) {

        if (isspace(input[i])) output[j++] = '+';

        else if (isalnum(input[i])) output[j++] = input[i];

        else j = j + sprintf(output + j, "%%%2.2X", input[i]);

    }

    output[j] = '\0';

    return;
}