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#include <fcntl.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include "buffer.h"
#include "byte.h"
#include "case.h"
#include "env.h"
#include "error.h"
#include "exit.h"
#include "fd.h"
#include "fmt.h"
#include "getln.h"
#include "logmsg.h"
#include "open.h"
#include "pathexec.h"
#include "sig.h"
#include "str.h"
#include "stralloc.h"
#include "uint_t.h"
#include "wait.h"
#include "control.h"
#include "fmtqfn.h"
#include "qmail.h"
#ifdef USE_CONFIG
#include "fehsqm-config.h"
#else
#include "auto_qmail.h"
#endif
#define WHO "qmail-dkverify"
/**
@file qmail-dkverify.c
@brief stub routine for DKIM signature verification and indication in received message
Steps:
------
a) Store message with CRLF
b) Get DKIM signature from message - if given:
c) Call qmail-dkim for verification
d) Include results as appended header
e) Queue the message for processing
*/
char bufin[1024]; // RFC 5322: 998 chars - why?
buffer bi = BUFFER_INIT(read, 0, bufin, sizeof(bufin)); // read buffer
char bufout[1024];
buffer bo = BUFFER_INIT(write, 1, bufout, sizeof(bufout)); // output message
void die(int e)
{
_exit(e);
}
void die_pipe(char *fn)
{
unlink(fn);
die(53);
}
void die_write(char *fn)
{
unlink(fn);
die(53);
}
void die_read()
{
die(54);
}
void out(char *s)
{
if (buffer_puts(&bo, s) == -1) _exit(111);
}
void zero()
{
if (buffer_put(&bo, "\0", 1) == -1) _exit(111);
}
void zerodie()
{
zero();
buffer_flush(&bo);
_exit(111);
}
void temp_nomem()
{
out("ZOut of memory. (#4.3.0)\n");
zerodie();
}
void temp_chdir()
{
out("ZUnable to switch to target directory. (#4.3.0)\n");
zerodie();
}
void temp_create()
{
out("ZUnable to create DKIM stage file. (#4.3.0)\n");
zerodie();
}
void temp_unlink()
{
out("ZUnable to unlink DKIM stage file. (#4.3.0)\n");
zerodie();
}
void temp_read()
{
out("ZUnable to read message. (#4.3.0)\n");
zerodie();
}
void temp_socket()
{
out("ZUnable to crate socket pair. (#4.3.0)\n");
zerodie();
}
void temp_control()
{
out("ZUnable to read control files. (#4.3.0)\n");
zerodie();
}
static stralloc me = {0};
static stralloc senddomain = {0};
static stralloc dkheader = {0};
static stralloc fndkin = {0};
static stralloc fndkout = {0};
static stralloc result = {0};
void fnmake_dkim(unsigned long id)
{
fndkin.len = fmtqfn(fndkin.s, "queue/dkim/", id, 1);
id += id;
fndkout.len = fmtqfn(fndkout.s, "queue/dkim/", id, 1);
}
void dkim_stage()
{
int r;
int fd;
char ch;
struct stat st;
if (!stralloc_ready(&fndkin, FMTQFN)) temp_nomem();
if (!stralloc_ready(&fndkout, FMTQFN)) temp_nomem();
fnmake_dkim(getpid()); // pre-staging
fd = open_excl(fndkin.s);
if (fd == -1) die_write(fndkin.s);
buffer_init(&bi, read, 0, bufin, sizeof(bufin));
buffer_init(&bo, write, fd, bufout, sizeof(bufout));
for (int i = 0;;) {
r = buffer_get(&bi, &ch, 1);
if (r == 0) break;
if (r == -1) temp_read();
while (ch != '\n') {
if (ch != '\r') buffer_put(&bo, &ch, 1);
r = buffer_get(&bi, &ch, 1);
if (r == -1) temp_read();
i++;
}
buffer_put(&bo, "\r\n", 2);
}
if (buffer_flush(&bo) == -1) die(51);
if (fstat(fd, &st) == -1) die_write(fndkin.s);
if (fsync(fd) == -1) die_write(fndkin.s);
if (close(fd) == -1) die_write(fndkin.s);
}
int mess_dkim()
{
stralloc line = {0};
int match;
int fd;
int at = 0;
int ket = 0;
int end = 0;
int len = 0;
int r = 0;
int i;
fd = open_read(fndkin.s);
if (fd == -1) die_read();
buffer_init(&bi, read, fd, bufin, sizeof(bufin));
if (!stralloc_copys(&senddomain, "")) temp_nomem();
for (;;) {
if (getln(&bi, &line, &match, '\n') == -1) temp_read();
if (case_starts(line.s, "DKIM-Signature: ")) r = 1;
if (r == 1) {
if (case_starts(line.s, "From: ")) { // fallback: From
at = str_chr(line.s, '@');
if (at < line.len) {
end = str_chr(line.s, '\n'); // From: user@senddomain\n
ket = str_chr(line.s, '>'); // From: User <user@senddomain>
len = (ket < end) ? ket : end;
len -= at - 1;
if (len) {
if (!stralloc_copyb(&senddomain, line.s + at + 1, len)) temp_nomem();
} else if (!stralloc_copys(&senddomain, "uknown"))
temp_nomem();
r = 2;
}
}
for (i = 0; i < line.len; ++i) { // d=domain.tld
if (*(line.s + i) == '=' && *(line.s + i - 1) == 'd') {
++i; // gotcha
while (*(line.s + i) != ';') {
if (!stralloc_catb(&senddomain, line.s + i, 1)) temp_nomem();
i++;
r = 3;
}
}
}
}
if (r >= 2 || !match) break;
}
if (senddomain.len < 2)
if (!stralloc_copys(&senddomain, "unknown")) temp_nomem();
if (!stralloc_0(&senddomain)) temp_nomem();
return r;
}
int dkim_verify()
{
int child;
int wstat;
char *(args[6]);
int r = -1;
args[0] = "qmail-dkim";
args[1] = "-V";
args[2] = fndkin.s;
args[3] = "none";
args[4] = fndkout.s;
args[5] = 0;
if (!(child = fork())) {
pathexec(args);
if (errno) _exit(111);
_exit(100);
}
wait_pid(&wstat, child);
if (wait_crashed(wstat)) return 1;
switch (r = wait_exitcode(wstat)) {
case 10: return 1;
default: return 0;
}
}
int dkim_result(const char *me)
{
int max = 64;
int fd;
int j;
char ch;
int r = 0;
if (!stralloc_copys(&result, "")) temp_nomem();
if ((fd = open_read(fndkout.s)) == -1) return 0; // nothing to read
while ((r = read(fd, bufin, sizeof(bufin))) > 0)
if (!stralloc_catb(&result, bufin, r)) temp_nomem();
if (!stralloc_0(&result)) temp_nomem();
if (result.len > 2) {
if (case_starts(result.s, "pass")) r = 0;
if (case_starts(result.s, "fail")) r = 35;
} else if (!stralloc_copys(&result, "unknown")) {
temp_nomem();
}
if (!stralloc_copys(&dkheader, "X-Authentication-Results: ")) temp_nomem();
if (!stralloc_cats(&dkheader, senddomain.s)) temp_nomem();
if (!stralloc_cats(&dkheader, "; dkim=")) temp_nomem();
for (j = 0; j < result.len; j++) {
ch = result.s[j];
if (ch == '\r' || ch == '\n' || ch == '\0') continue;
if (j <= max)
if (!stralloc_catb(&dkheader, &ch, 1)) temp_nomem();
if (ch == ' ' && (j > max)) {
if (!stralloc_cats(&dkheader, "\n ")) temp_nomem();
max += max;
}
}
if (!stralloc_cats(&dkheader, "; ")) temp_nomem();
if (!stralloc_cats(&dkheader, me)) temp_nomem();
if (!stralloc_0(&dkheader)) temp_nomem();
return r;
}
int qmail_queue()
{
int fd;
int r;
int child;
int wstat;
int pi[2];
char *(args[2]);
char ch;
if (pipe(pi) == -1) die_pipe(fndkin.s);
args[0] = "qmail-queue";
args[1] = 0;
switch (child = vfork()) {
case -1:
close(pi[0]);
close(pi[1]);
die_write(fndkin.s);
case 0:
close(pi[1]);
if (fd_move(0, pi[0]) == -1) die_pipe(fndkin.s);
sig_pipedefault();
pathexec(args);
if (errno) _exit(111);
_exit(100);
}
close(pi[0]);
buffer_init(&bo, write, pi[1], bufout, sizeof(bufout));
if (dkheader.len > 2) { // write DKIM header
if (buffer_put(&bo, dkheader.s, dkheader.len - 1) == -1) die_write(fndkout.s);
if (buffer_put(&bo, "\n", 1) == -1) die_write(fndkout.s);
if (buffer_flush(&bo) == -1) die_write(fndkout.s);
}
/* read/write message byte-by-byte; we need to remove the CR (inefficient) */
if ((fd = open_read(fndkin.s)) == -1) die_read();
while ((r = read(fd, &ch, 1)) > 0)
if (ch != '\r')
if (buffer_put(&bo, &ch, 1) == -1) die_write(fndkin.s);
if (buffer_flush(&bo) == -1) die_write(fndkin.s);
close(pi[1]);
wait_pid(&wstat, child);
if (wait_crashed(wstat)) return 1;
switch (r = wait_exitcode(wstat)) {
case 10: return 1;
default: return 0;
}
return 0;
}
void dkim_unlink()
{
if (unlink(fndkin.s) == -1)
if (errno != ENOENT) temp_unlink();
if (unlink(fndkout.s) == -1)
if (errno != ENOENT) temp_unlink();
}
int main()
{
int r = 0;
char *mode = 0;
umask(033);
if (chdir(auto_qmail) == -1) temp_chdir();
if (control_init() == -1) temp_control();
if (control_readline(&me, "control/me") == -1) temp_control();
if (!stralloc_0(&me)) temp_nomem();
dkim_stage();
if (mess_dkim()) {
dkim_verify();
r = dkim_result(me.s);
}
/* we are done: call qmail-queue */
mode = env_get("DKIM");
if (!mode || *mode != '+') r = 0;
qmail_queue();
dkim_unlink();
_exit(r);
}
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