#include <stdio.h>
#include <string.h>

/**************************************************************
認証用ユーザIDとパスワードから，「認証用ユーザID+'\0'+認証用ユーザID+'\0'+パスワード」の
文字列をBASE64でMIME変換した文字列を生成する
AuthPlainGenarator
genarating auth plain string from userID and password
usage:
    AuthPlainGenerator userID password
    AuthPlainGenerator /c
example:
    AuthPlainGenerator watashi watahinopassword
    AuthPlainGenerator taro uso800
**************************************************************/
//mime変換のためのテーブル      0123456789012345678901234567890123456789012345678901234567890123
const char MimeEncodeTable[70]="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

//文字列intext(normal)を文字列otext(mime encoded)に変換
//BASE64を利用したMIME変換
void PureMimeEncode(char *intext, char *otext, int len)
{
    unsigned char *p;
    unsigned long int x,x1;
    unsigned char tmp[8]={0,0,0,0,0,0,0,0};
    char one[4]="A";
    int add,len1,i,j;
    add=0;
    len1=len;
    if (len%3!=0) {
        add= 3-(len%3);
        len1=len/3*3;
    }
    p=(unsigned char *)intext;
    *otext=0;
    for (i=0; i<len1; i+=3) {
        x=(p[0]<<16)+(p[1]<<8)+p[2];
        x1=(x>>18)&0x3f; one[0]=MimeEncodeTable[x1]; strcat(otext,one);
        x1=(x>>12)&0x3f; one[0]=MimeEncodeTable[x1]; strcat(otext,one);
        x1=(x>>06)&0x3f; one[0]=MimeEncodeTable[x1]; strcat(otext,one);
        x1=(   x )&0x3f; one[0]=MimeEncodeTable[x1]; strcat(otext,one);
        p+=3;
    }
    if (add) {
        for (j=0 ; i<len; i++,j++) tmp[j]=*p++;
        x=(tmp[0]<<16)+(tmp[1]<<8)+tmp[2];
        x1=(x>>18)&0x3f; one[0]=MimeEncodeTable[x1]; strcat(otext,one);
        x1=(x>>12)&0x3f; one[0]=MimeEncodeTable[x1]; strcat(otext,one);
        x1=(x>>06)&0x3f; one[0]=MimeEncodeTable[x1]; strcat(otext,one);
        x1=(   x )&0x3f; one[0]=MimeEncodeTable[x1]; strcat(otext,one);
    }
    //add=0 -> del=0, add=1 -> del=1, add=2 -> del=2
    p=otext+strlen(otext)-1;
    for (i=0; i<add; i++) *p--='=';
}

//ユーザIDuserとパスワードpassからauth文字列（mime(user\0user\0pass)）を作る
void makeAuthPlain(char *user, char *pass, char *auth)
{
    int num,i;
    char plain[256];
    strcpy(plain,user);
    strcat(plain,"\t");
    strcat(plain,user);
    strcat(plain,"\t");
    strcat(plain,pass);
    //puts(plain);
    num=strlen(plain);
    for (i=0;i<num;i++) if (plain[i]=='\t') plain[i]=0;
    PureMimeEncode(plain,auth,num);
}

int main(int argc, char *argv[])
{
    char userid[256],passwd[256];
    char MimeEncoded[256];
    if (argc==1) {
        printf("AuthPlainGenarator\n");
        printf("genarating auth plain string from userID and password\n");
        printf("Please enter userID and password\n");
        printf("userID :");
        gets(userid);
        printf("password :");
        gets(passwd);
    } else if (argc==2) {
        printf("AuthPlainGenarator\n");
        printf("genarating auth plain string from userID and password\n");
        printf("usage:\n");
        printf("    AuthPlainGenerator userID password\n");
        printf("    AuthPlainGenerator /c\n");
        printf("example:\n");
        printf("    AuthPlainGenerator watashi watahinopassword\n");
        printf("    AuthPlainGenerator taro uso800\n");
        getchar();
        return 1;
    } else {
        strcpy(userid,argv[1]);
        strcpy(passwd,argv[2]);
    }
    printf("userID: %s\n",userid);
    printf("passwd: %s\n",passwd);
    makeAuthPlain(userid, passwd, MimeEncoded);
    printf("auth plain string: %s\n",MimeEncoded);
    getchar();
    return 0;
}