/*
 * 20111227
 * Jan Mojzis
 * derived from qmail-1.03/qmail-remote.c
 * Public domain.
 */

#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <signal.h>
#include "timeoutread.h"
#include "timeoutwrite.h"
#include "buffer.h"
#include "stralloc.h"
#include "fmt.h"
#include "env.h"
#include "scan.h"
#include "str.h"

#define HUGESMTPTEXT 5000

const char *helohost = 0;
const char *remoteip = 0;

void out(const char *s) { if (buffer_puts(buffer_1small, s) == -1) _exit(0); }
void zero(void) { if (buffer_put(buffer_1small,"",1) == -1) _exit(0); }
void zerodie(void) { zero(); buffer_flush(buffer_1small); _exit(0); }

void temp_nomem(void) { out("ZOut of memory. (#4.3.0)\n"); zerodie(); }
void temp_read(void) { out("ZUnable to read message. (#4.3.0)\n"); zerodie(); }
void perm_partialline(void) { out("D\
SMTP cannot transfer messages with partial final lines. (#5.6.2)\n"); zerodie(); }
void perm_usage(void) { out("D\
I (qmail-rsmtp) was invoked improperly. (#5.3.5)\n"); zerodie(); }


void outhost(void) {
    buffer_puts(buffer_1small, remoteip);
}

int flagcritical = 0;

void dropped(void) {
    out("ZConnected to ");
    outhost();
    out(" but connection died. ");
    if (flagcritical) out("Possible duplicate! ");
    out("(#4.4.2)\n");
    zerodie();
}


unsigned long timeout = 1200;

int unixread(int fd, char *buf, unsigned int len) {
    int r;
    r = read(fd, buf, len);
    if (r == -1) temp_read();
    return r;
}

int saferead(int fd, char *buf, unsigned int len) {
    int r;
    r = timeoutread(timeout, fd, buf, len);
    if (r <= 0) dropped();
    return r;
}

int safewrite(int fd, char *buf, unsigned int len) {
    int r;
    r = timeoutwrite(timeout, fd, buf, len);
    if (r <= 0) dropped();
    return r;
}

char inbuf[1024];
buffer in = BUFFER_INIT(unixread,0,inbuf,sizeof inbuf);
char netreadspace[128];
buffer netread = BUFFER_INIT(saferead,6,netreadspace,sizeof netreadspace);
char smtptospace[1024];
buffer smtpto = BUFFER_INIT(safewrite,7,smtptospace,sizeof smtptospace);

stralloc smtptext = {0};
stralloc smtpline = {0};


void get(unsigned char *ch) {

    buffer_get(&netread,(char *)ch,1);
    if (*ch != '\r') {
        if (smtptext.len < HUGESMTPTEXT) {
            if (!stralloc_append(&smtptext,(char *)ch)) temp_nomem();
        }
        if (smtpline.len < HUGESMTPTEXT) {
            if (!stralloc_append(&smtpline,(char *)ch)) temp_nomem();
        }
    }
}

unsigned long smtpcode(void (*callback)(unsigned long, const char *)) {

    unsigned char ch;
    unsigned long code;

    if (!stralloc_copys(&smtptext,"")) temp_nomem();

    get(&ch); code = ch - '0';
    get(&ch); code = code * 10 + (ch - '0');
    get(&ch); code = code * 10 + (ch - '0');
    for (;;) {
        get(&ch);
        if (ch != '-') break;
        if (callback) if (!stralloc_copys(&smtpline,"")) temp_nomem();
        while (ch != '\n') get(&ch);
        if (callback) if (!stralloc_0(&smtpline)) temp_nomem();
        if (callback) callback(code, smtpline.s);
        get(&ch);
        get(&ch);
        get(&ch);
    }
    if (callback) if (!stralloc_copys(&smtpline,"")) temp_nomem();
    while (ch != '\n') get(&ch);
    if (callback) if (!stralloc_0(&smtpline)) temp_nomem();
    if (callback) callback(code, smtpline.s);

    return code;
}


void outsmtptext(void) {

    unsigned int i;
    if (smtptext.s) if (smtptext.len) {
        out("Remote host said: ");
        for (i = 0;i < smtptext.len;++i)
            if (!smtptext.s[i]) smtptext.s[i] = '?';
        if (buffer_put(buffer_1small,smtptext.s,smtptext.len) == -1) _exit(0);
        smtptext.len = 0;
    }
}


void outsmtptext2(void) {

    unsigned int i;
    if (smtptext.s) if (smtptext.len) {
        buffer_puts(buffer_2, "Remote host said: ");
        for (i = 0;i < smtptext.len;++i)
            if (!smtptext.s[i]) smtptext.s[i] = '?';
        buffer_put(buffer_2,smtptext.s,smtptext.len);
        smtptext.len = 0;
    }
}


void quit(const char *prepend, const char *append) {

    buffer_putsflush(&smtpto,"QUIT\r\n");
    out(prepend);
    outhost();
    out(append);
    out(".\n");
    outsmtptext();
    zerodie();
}

void quit2(const char *prepend, const char *append) {
    buffer_putsflush(&smtpto,"QUIT\r\n");
    buffer_puts(buffer_2, prepend);
    buffer_puts(buffer_2, remoteip);
    buffer_puts(buffer_2, append);
    buffer_puts(buffer_2, ".\n");
    outsmtptext2();
    buffer_flush(buffer_2);
    _exit(0);
}


void blast(void) {

    int r;
    char ch;

    for (;;) {
        r = buffer_get(&in,&ch,1);
        if (r == 0) break;
        if (ch == '.')
            buffer_puts(&smtpto, ".");
        while (ch != '\n') {
            buffer_put(&smtpto, &ch, 1);
            r = buffer_get(&in,&ch,1);
            if (r == 0) perm_partialline(); 
        }
        buffer_puts(&smtpto, "\r\n");
    }

    flagcritical = 1;
    buffer_puts(&smtpto, ".\r\n");
    buffer_flush(&smtpto);
}


int flagsize = 0;

void ehlo_callback(unsigned long code, const char *line) {

    if (code != 250) return;

    if (str_start(line, "SIZE "))
        flagsize = 1;
    return;
}


char strnum[FMT_LONGLONG];


int main(int argc, char **argv) {

    unsigned long code;
    unsigned int i;
    struct stat st;
    int flagbother;
    const char *x;

    if (argc < 3) perm_usage();

    signal(SIGPIPE,SIG_IGN);

    /* get timeout */
    x = env_get("TIMEOUT");
    if (x) scan_ulong(x, &timeout);
    if (timeout < 1) timeout = 1;
    if (timeout > 3600) timeout = 3600;

    /* get helohost */
    if (!helohost) helohost = env_get("HELOHOST");
    if (!helohost) helohost = "";

    /* get remoteip */
    if (!remoteip) remoteip = env_get("REMOTEIP");
    if (!remoteip) remoteip = "0";

    code = smtpcode(0);
    if (code >= 500) quit("ZConnected to "," but greeting failed");
    if (code != 220) quit2("Connected to "," but greeting failed"); /* XXX: try next MX */

    buffer_puts(&smtpto, "EHLO ");
    buffer_puts(&smtpto, helohost);
    buffer_puts(&smtpto, "\r\n");
    buffer_flush(&smtpto);
    code = smtpcode(ehlo_callback);
    if (code != 250) {
        buffer_puts(&smtpto, "HELO ");
        buffer_puts(&smtpto, helohost);
        buffer_puts(&smtpto, "\r\n");
        buffer_flush(&smtpto);
        code = smtpcode(0);
        if (code != 250) quit("ZConnected to "," but my name was rejected");
    }

    buffer_puts(&smtpto, "MAIL FROM:<");
    buffer_puts(&smtpto, argv[1]);
    buffer_puts(&smtpto, ">");
    if (flagsize && fstat(0, &st) == 0) {
        buffer_puts(&smtpto, " SIZE=");
        buffer_put(&smtpto, strnum, fmt_ulonglong(strnum, st.st_size));
    }
    buffer_puts(&smtpto, "\r\n");
    buffer_flush(&smtpto);
    code = smtpcode(0);
    if (code >= 500) quit("DConnected to "," but sender was rejected");
    if (code >= 400) quit("ZConnected to "," but sender was rejected");

    i = 2;
    flagbother = 0;
    while (argv[i]) {
        buffer_puts(&smtpto, "RCPT TO:<");
        buffer_puts(&smtpto, argv[i]);
        buffer_puts(&smtpto, ">\r\n");
        buffer_flush(&smtpto);
        code = smtpcode(0);
        if (code >= 500) {
            out("h"); outhost(); out(" does not like recipient.\n");
            outsmtptext(); zero();
        }
        else if (code >= 400) {
            out("s"); outhost(); out(" does not like recipient.\n");
            outsmtptext(); zero();
        }
        else {
            out("r"); zero();
            flagbother = 1;
        }
        ++i;
    }
    if (!flagbother) quit("DGiving up on ","");

    buffer_putsflush(&smtpto,"DATA\r\n");
    code = smtpcode(0);
    if (code >= 500) quit("D"," failed on DATA command");
    if (code >= 400) quit("Z"," failed on DATA command");

    blast();
    code = smtpcode(0);
    flagcritical = 0;
    if (code >= 500) quit("D"," failed after I sent the message");
    if (code >= 400) quit("Z"," failed after I sent the message");
    quit("K"," accepted message");
}