send_sms from linux host

#include <stdio.h>   /* Standard input/output definitions */
#include <string.h>  /* String function definitions */
#include <unistd.h>  /* UNIX standard function definitions */
#include <fcntl.h>   /* File control definitions */
#include <errno.h>   /* Error number definitions */
#include <termios.h> /* POSIX terminal control definitions */
#include <stdlib.h>

int
modem_send_cmd(int *fd, char *cmd, char *ret) {
        int rd;

        tcflush(*fd, TCIFLUSH);
        write(*fd, cmd, strlen(cmd));
        sleep(1);
        rd = read(*fd, ret, 255);
        ret[rd] = '\0';

        return (0);
}

int
sendsms(int *fd, char *num, char *msg)
{
        char *cmd1 = "AT+CMGF=1\r";
        char *cmd2;
        char res[256];

        char *ctl_z = "\x1A\x00";

        cmd2 = (char*)malloc(strlen(num) + 20);
        strcpy(cmd2, "AT+CMGS=\"");
        strcat(cmd2, num);
        strcat(cmd2, "\"\r");

        modem_send_cmd(fd, cmd1, res);
        modem_send_cmd(fd, cmd2, res);
        modem_send_cmd(fd, msg, res);
        modem_send_cmd(fd, ctl_z, res);

        return (0);
}


int
main(int argc, char **argv)
{
        int fd;
	if (argc != 3) {
                printf("usage: %s Message Phone_no\n", argv[0]);
                exit (3);
        }

        char *msg = (char*) malloc(50 * sizeof(char));
        char *phone = (char*) malloc(10 * sizeof(char));
        strcpy(msg, argv[1]);
        strcpy(phone, argv[2]);
        struct termios options, oldconf;
	fd = open("/dev/ttyUSB0", O_RDWR | O_NOCTTY | O_NDELAY);
        if (fd == -1)
                perror("open_port: Unable to open /dev/ttyUSB0 - ");
        else
                fcntl(fd, F_SETFL, 0);
        tcgetattr(fd, &oldconf);
        memset(&options, 0, sizeof(options));


        cfsetispeed(&options, B4800);
        cfsetospeed(&options, B4800);

        options.c_cflag |= (CLOCAL | CREAD);
        options.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG);
        options.c_oflag &= ~OPOST;
        options.c_cc[VMIN] = 0;
        options.c_cc[VTIME] = 10;
        tcflush(fd, TCIFLUSH);
        tcsetattr(fd, TCSANOW, &options);
        if (sendsms(&fd, phone, msg) == 0)
                printf("successfully sent\n");
        /*
         * kplease return the terminal to normal as it was here
         */
        tcsetattr(fd,TCSANOW,&oldconf);
        close(fd);
        return (0);
}