/*
 * 20111228
 * Jan Mojzis
 * derived from qmail-1.03/qmail-remote.c
 * Public domain.
 */

/*
TODO:
... tcpto
... CNAME handling
*/

#include <unistd.h>
#include <signal.h>
#include "control.h"
#include "buffer.h"
#include "constmap.h"
#include "stralloc.h"
#include "auto_qmail.h"
#include "str.h"
#include "byte.h"
#include "scan.h"
#include "dns.h"
#include "curveresolve.h"
#include "pathexec.h"
#include "ip4.h"
#include "alloc.h"
#include "forkexecreadwait.h"
#include "ipalloc.h"
#include "error.h"
#include "fmt.h"
#include "ipme.h" 
#include "dns_mxip.h"

#define PORT_SMTP 25 /* silly rabbit, /etc/services is for users */
unsigned long port = PORT_SMTP;

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_noconn(const char *s) { out("Z\
Sorry, I wasn't able to establish an SMTP connection. (#4.4.1)\n"); out(s); zerodie(); }
void temp_nomem(void) { out("ZOut of memory. (#4.3.0)\n"); zerodie(); }
void temp_oserr(void) { out("Z\
System resources temporarily unavailable. (#4.3.0)\n"); zerodie(); }
void temp_control(void) { out("Z\
Unable to read control files. (#4.3.0)\n"); zerodie(); }
void temp_chdir(void) { out("Z\
Unable to switch to home directory. (#4.3.0)\n"); zerodie(); }
void perm_usage(void) { out("D\
I (qmail-remote) was invoked improperly. (#5.3.5)\n"); zerodie(); }
void temp_dns(void) { out("Z\
Sorry, I couldn't find any host by that name. (#4.1.2)\n"); zerodie(); }
void perm_nomx(void) { out("D\
Sorry, I couldn't find a mail exchanger or IP address. (#5.4.4)\n");
zerodie(); }
void perm_ambigmx(void) { out("D\
Sorry. Although I'm listed as a best-preference MX or A for that host,\n\
it isn't in my control/locals file, so I don't treat it as local. (#5.4.6)\n");
zerodie(); }


stralloc helohost = {0};
stralloc routes = {0};
stralloc host = {0};
stralloc dnsout = {0};
stralloc fqdn = {0};
stralloc sender = {0};
struct constmap maproutes;
int timeoutconnect = 60;
int timeout = 1200;

static char seed[128];

int flagkeydir = 0;
stralloc keydir = {0};


void getcontrols(void) {

    if (control_init() == -1) temp_control();
    if (control_readint(&timeout,"control/timeoutremote") == -1) temp_control();
    if (control_readint(&timeoutconnect,"control/timeoutconnect") == -1)
        temp_control();
    if (control_rldef(&helohost,"control/helohost",1,(char *) 0) != 1)
        temp_control();
    flagkeydir = control_rldef(&keydir,"control/keydir",0,(char *) 0);
    if (flagkeydir == -1) temp_control();
    if (!stralloc_0(&keydir)) temp_nomem();
    switch(control_readfile(&routes,"control/smtproutes",0)) {
        case -1:
            temp_control();
        case 0:
            if (!constmap_init(&maproutes,"",0,1)) temp_nomem(); break;
        case 1:
            if (!constmap_init(&maproutes,routes.s,routes.len,1)) temp_nomem(); break;
    }
}


static stralloc data    = {0};
static stralloc data2   = {0};
static char ipstr[IP4_FMT];
static char strport[FMT_ULONG];
static char strtimeout[FMT_ULONG];


void child(stralloc *d1, stralloc *d2, struct ip_mx *ix, int argc, char **argv, char **envp) {

    int i,j;
    char ** run;

    ipstr[ip4_fmt(ipstr,ix->ip)] = 0;
    strport[fmt_ulong(strport, port)] = 0;
    strtimeout[fmt_ulong(strtimeout, timeoutconnect)] = 0;

    if (!pathexec_env((char *)"REMOTEIP", ipstr)) temp_nomem();
    if (!pathexec_env((char *)"REMOTEHOST", ix->name)) temp_nomem();

    run = (char **)alloc((argc + 20) * (sizeof (const char **)));
    if (!run) temp_nomem();

    i = 0;
    if (ix->haskey) {
        run[i++] = "qmail-curvecpclient";
        if (flagkeydir) {
            run[i++] = "-c";
            run[i++] = keydir.s;
        }
        run[i++] = "-v";
        run[i++] = ix->name;
        run[i++] = ix->key;
        run[i++] = ipstr;
        run[i++] = strport;
        run[i++] = ix->ext;
        run[i++] = "qmail-curvecpmessage";
        run[i++] = "-c";
    }
    else {
        run[i++] = "qmail-tcpclient";
        run[i++] = "-T";
        run[i++] = strtimeout;
        run[i++] = "-HDRl0";
        run[i++] = ipstr;
        run[i++] = strport;
    }
    run[i++] = "qmail-rsmtp";

    for(j = 2; j < argc; ++j){
        run[i++] = argv[j];
    }
    run[i++] = 0;

    forkexecreadwait(d1, d2, run);
}


ipalloc ip = {0};

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

    char *relayhost;
    unsigned int i;
    int prefme;

    signal(SIGPIPE,SIG_IGN);

    if (argc < 4) perm_usage();
    if (chdir(auto_qmail) == -1) temp_chdir();
    getcontrols();

    helohost.s[helohost.len] = 0;
    if (!pathexec_env("HELOHOST", helohost.s)) temp_nomem();

    if (!stralloc_copys(&host,argv[1])) temp_nomem();

    relayhost = 0;
    for (i = 0;i <= host.len;++i)
        if ((i == 0) || (i == host.len) || (host.s[i] == '.')) {
            relayhost = constmap(&maproutes,host.s + i,host.len - i);
            if (relayhost) break;
        }
    if (relayhost && !*relayhost) relayhost = 0;

    if (relayhost) {
        i = str_chr(relayhost,':');
        if (relayhost[i]) {
            scan_ulong(relayhost + i + 1,&port);
            relayhost[i] = 0;
        }
        if (!stralloc_copys(&host,relayhost)) temp_nomem();
    }

    if (ipme_init() != 1) temp_oserr(); 
    dns_random_init(seed);
    if (dns_mxip(&ip,&host,relayhost) == -1) temp_dns();
    if (ip.len <= 0) perm_nomx();

    prefme = 100000;
    for (i = 0;i < ip.len;++i)
        if (ipme_is(ip.ix[i].ip))
            if (ip.ix[i].pref < prefme)
                prefme = ip.ix[i].pref;

    if (relayhost) prefme = 300000;

    for (i = 0;i < ip.len;++i)
        if (ip.ix[i].pref < prefme)
            break;

    if (i >= ip.len)
        perm_ambigmx();

    if (!stralloc_copys(&data,"")) temp_nomem();
    if (!stralloc_copys(&data2,"")) temp_nomem();

    for (i = 0;i < ip.len;++i) if (ip.ix[i].pref < prefme) {
        /* XXX TODO: if (tcpto(ip.ix[i].ip)) continue; */
        if (!stralloc_copys(&data,"")) temp_nomem();
        child(&data, &data2, &ip.ix[i], argc, argv, envp);
        if (data.len > 0) {
            /* XXX TODO:  tcpto_err(ip.ix[i].ip,0); */
            if (buffer_put(buffer_1small, data.s, data.len) == -1) _exit(0);
            if (buffer_flush(buffer_1small) == -1) _exit(0);
            _exit(0);
        }
    }
    /* XXX TODO: tcpto_err(ip.ix[i].ip,errno == error_timeout); */
    if (!stralloc_0(&data2)) temp_nomem();
    temp_noconn(data2.s);
}