/*
- * citmail.c v4.2
- * $Id$
- *
- * This program may be used as a local mail delivery agent, which will allow
- * all Citadel users to receive Internet e-mail. To enable this functionality,
- * you must tell sendmail, smail, or whatever mailer you are using, that this
- * program is your local mail delivery agent. This program is a direct
- * replacement for lmail, deliver, or whatever.
+ *
+ * Completely reworked version of "citmail"
+ * This program attempts to act like a local MDA if you're using sendmail or
+ * some other non-Citadel MTA. It basically just forwards the message to
+ * the Citadel SMTP listener on some non-standard port.
*
- * Usage:
- *
- * citmail <recipient> - Deliver a message
- * citmail -t <recipient> - Address test mode (will not deliver)
+ * $Id$
*
*/
#include "sysdep.h"
#include <stdlib.h>
#include <unistd.h>
-#include <stdio.h>
-#include <fcntl.h>
#include <ctype.h>
+#include <stdio.h>
+#include <signal.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <netdb.h>
#include <string.h>
-#include <time.h>
#include <pwd.h>
#include <errno.h>
-#include <syslog.h>
-#include <limits.h>
+#include <stdarg.h>
#include "citadel.h"
-#include "config.h"
-#include "internetmail.h"
+#include "citadel_decls.h"
+#include "ipc.h"
+#ifndef HAVE_SNPRINTF
+#include "snprintf.h"
+#endif
+#ifndef INADDR_NONE
+#define INADDR_NONE 0xffffffff
+#endif
-extern time_t parsedate(char *p);
+int serv_sock;
-/* message delivery classes */
-enum {
- DELIVER_LOCAL,
- DELIVER_REMOTE,
- DELIVER_INTERNET,
- DELIVER_CCITADEL
-};
-
+void strip_trailing_nonprint(char *buf)
+{
+ while ( (strlen(buf)>0) && (!isprint(buf[strlen(buf) - 1])) )
+ buf[strlen(buf) - 1] = 0;
+}
-#undef tolower
-#define tolower(x) isupper(x) ? (x+'a'-'A') : x
-char *monthdesc[] =
-{"Jan", "Feb", "Mar", "Apr", "May", "Jun",
- "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"};
-char ALIASES[128];
-char CIT86NET[128];
-char SENDMAIL[128];
-char FALLBACK[128];
-char GW_DOMAIN[128];
-char TABLEFILE[128];
-char OUTGOING_FQDN[128];
-int RUN_NETPROC = 1;
-#ifndef HAVE_STRERROR
-/*
- * replacement strerror() for systems that don't have it
- */
-char *strerror(int e)
+void timeout(int signum)
{
- static char buf[32];
-
- snprintf(buf, sizeof buf, "errno = %d", e);
- return (buf);
+ exit(signum);
}
-#endif
-int haschar(char *st, int ch)
-{
- int a, b;
- b = 0;
- for (a = 0; a < strlen(st); ++a)
- if (st[a] == ch)
- ++b;
- return (b);
-}
-void strip_trailing_whitespace(char *buf)
+int connectsock(char *host, char *service, char *protocol)
{
- while (isspace(buf[strlen(buf) - 1]))
- buf[strlen(buf) - 1] = 0;
-}
+ struct hostent *phe;
+ struct servent *pse;
+ struct protoent *ppe;
+ struct sockaddr_in sin;
+ int s, type;
+
+ memset(&sin, 0, sizeof(sin));
+ sin.sin_family = AF_INET;
+
+ pse = getservbyname(service, protocol);
+ if (pse) {
+ sin.sin_port = pse->s_port;
+ } else if ((sin.sin_port = htons((u_short) atoi(service))) == 0) {
+ fprintf(stderr, "Can't get %s service entry: %s\n",
+ service, strerror(errno));
+ exit(3);
+ }
+ phe = gethostbyname(host);
+ if (phe) {
+ memcpy(&sin.sin_addr, phe->h_addr, phe->h_length);
+ } else if ((sin.sin_addr.s_addr = inet_addr(host)) == INADDR_NONE) {
+ fprintf(stderr, "Can't get %s host entry: %s\n",
+ host, strerror(errno));
+ exit(3);
+ }
+ if ((ppe = getprotobyname(protocol)) == 0) {
+ fprintf(stderr, "Can't get %s protocol entry: %s\n",
+ protocol, strerror(errno));
+ exit(3);
+ }
+ if (!strcmp(protocol, "udp")) {
+ type = SOCK_DGRAM;
+ } else {
+ type = SOCK_STREAM;
+ }
-/* strip leading and trailing spaces */
-void striplt(char *buf)
-{
- while ((strlen(buf) > 0) && (buf[0] == 32))
- strcpy(buf, &buf[1]);
- while (buf[strlen(buf) - 1] == 32)
- buf[strlen(buf) - 1] = 0;
-}
+ s = socket(PF_INET, type, ppe->p_proto);
+ if (s < 0) {
+ fprintf(stderr, "Can't create socket: %s\n", strerror(errno));
+ exit(3);
+ }
+ signal(SIGALRM, timeout);
+ alarm(30);
+
+ if (connect(s, (struct sockaddr *) &sin, sizeof(sin)) < 0) {
+ fprintf(stderr, "can't connect to %s.%s: %s\n",
+ host, service, strerror(errno));
+ exit(3);
+ }
+ alarm(0);
+ signal(SIGALRM, SIG_IGN);
+ return (s);
+}
/*
- * Check to see if a given FQDN really maps to a Citadel network node
+ * convert service and host entries into a six-byte numeric in the format
+ * expected by a SOCKS v4 server
*/
-void host_alias(char host[])
+void numericize(char *buf, char *host, char *service, char *protocol)
{
-
- int a;
-
- /* What name is the local host known by? */
- /* if (!strcasecmp(host, config.c_fqdn)) { */
- if (IsHostLocal(host)) {
- strcpy(host, config.c_nodename);
- return;
+ struct hostent *phe;
+ struct servent *pse;
+ struct sockaddr_in sin;
+
+ memset(&sin, 0, sizeof(sin));
+ sin.sin_family = AF_INET;
+
+ pse = getservbyname(service, protocol);
+ if (pse) {
+ sin.sin_port = pse->s_port;
+ } else if ((sin.sin_port = htons((u_short) atoi(service))) == 0) {
+ fprintf(stderr, "Can't get %s service entry: %s\n",
+ service, strerror(errno));
+ exit(3);
}
- /* Other hosts in the gateway domain? */
- for (a = 0; a < strlen(host); ++a) {
- if ((host[a] == '.') && (!strcasecmp(&host[a + 1], GW_DOMAIN))) {
- host[a] = 0;
- for (a = 0; a < strlen(host); ++a) {
- if (host[a] == '.')
- host[a] = 0;
- }
- return;
- }
+ buf[1] = (((sin.sin_port) & 0xFF00) >> 8);
+ buf[0] = ((sin.sin_port) & 0x00FF);
+
+ phe = gethostbyname(host);
+ if (phe) {
+ memcpy(&sin.sin_addr, phe->h_addr, phe->h_length);
+ } else if ((sin.sin_addr.s_addr = inet_addr(host)) == INADDR_NONE) {
+ fprintf(stderr, "Can't get %s host entry: %s\n",
+ host, strerror(errno));
+ exit(3);
}
-
- /* Otherwise, do nothing... */
+ buf[5] = ((sin.sin_addr.s_addr) & 0xFF000000) >> 24;
+ buf[4] = ((sin.sin_addr.s_addr) & 0x00FF0000) >> 16;
+ buf[3] = ((sin.sin_addr.s_addr) & 0x0000FF00) >> 8;
+ buf[2] = ((sin.sin_addr.s_addr) & 0x000000FF);
}
-
-
/*
- * Split an RFC822-style address into userid, host, and full name
+ * input binary data from socket
*/
-void process_rfc822_addr(char *rfc822, char *user, char *node, char *name)
+void serv_read(char *buf, int bytes)
{
- int a;
-
- /* extract full name - first, it's From minus <userid> */
- strcpy(name, rfc822);
- for (a = 0; a < strlen(name); ++a)
- if (name[a] == '<') {
- do {
- strcpy(&name[a], &name[a + 1]);
- } while ((strlen(name) > 0) && (name[a] != '>'));
- strcpy(&name[a], &name[a + 1]);
- }
- /* strip anything to the left of a bang */
- while ((strlen(name) > 0) && (haschar(name, '!') > 0))
- strcpy(name, &name[1]);
-
- /* and anything to the right of a @ or % */
- for (a = 0; a < strlen(name); ++a) {
- if (name[a] == '@')
- name[a] = 0;
- if (name[a] == '%')
- name[a] = 0;
- }
-
- /* but if there are parentheses, that changes the rules... */
- if ((haschar(rfc822, '(') == 1) && (haschar(rfc822, ')') == 1)) {
- strcpy(name, rfc822);
- while ((strlen(name) > 0) && (name[0] != '(')) {
- strcpy(&name[0], &name[1]);
- }
- strcpy(&name[0], &name[1]);
- for (a = 0; a < strlen(name); ++a)
- if (name[a] == ')')
- name[a] = 0;
- }
- /* but if there are a set of quotes, that supersedes everything */
- if (haschar(rfc822, 34) == 2) {
- strcpy(name, rfc822);
- while ((strlen(name) > 0) && (name[0] != 34)) {
- strcpy(&name[0], &name[1]);
- }
- strcpy(&name[0], &name[1]);
- for (a = 0; a < strlen(name); ++a)
- if (name[a] == 34)
- name[a] = 0;
- }
- /* extract user id */
- strcpy(user, rfc822);
-
- /* first get rid of anything in parens */
- for (a = 0; a < strlen(user); ++a)
- if (user[a] == '(') {
- do {
- strcpy(&user[a], &user[a + 1]);
- } while ((strlen(user) > 0) && (user[a] != ')'));
- strcpy(&user[a], &user[a + 1]);
- }
- /* if there's a set of angle brackets, strip it down to that */
- if ((haschar(user, '<') == 1) && (haschar(user, '>') == 1)) {
- while ((strlen(user) > 0) && (user[0] != '<')) {
- strcpy(&user[0], &user[1]);
- }
- strcpy(&user[0], &user[1]);
- for (a = 0; a < strlen(user); ++a)
- if (user[a] == '>')
- user[a] = 0;
- }
- /* strip anything to the left of a bang */
- while ((strlen(user) > 0) && (haschar(user, '!') > 0))
- strcpy(user, &user[1]);
-
- /* and anything to the right of a @ or % */
- for (a = 0; a < strlen(user); ++a) {
- if (user[a] == '@')
- user[a] = 0;
- if (user[a] == '%')
- user[a] = 0;
- }
+ int len, rlen;
-
-
- /* extract node name */
- strcpy(node, rfc822);
-
- /* first get rid of anything in parens */
- for (a = 0; a < strlen(node); ++a)
- if (node[a] == '(') {
- do {
- strcpy(&node[a], &node[a + 1]);
- } while ((strlen(node) > 0) && (node[a] != ')'));
- strcpy(&node[a], &node[a + 1]);
- }
- /* if there's a set of angle brackets, strip it down to that */
- if ((haschar(node, '<') == 1) && (haschar(node, '>') == 1)) {
- while ((strlen(node) > 0) && (node[0] != '<')) {
- strcpy(&node[0], &node[1]);
+ len = 0;
+ while (len < bytes) {
+ rlen = read(serv_sock, &buf[len], bytes - len);
+ if (rlen < 1) {
+ return;
}
- strcpy(&node[0], &node[1]);
- for (a = 0; a < strlen(node); ++a)
- if (node[a] == '>')
- node[a] = 0;
+ len = len + rlen;
}
- /* strip anything to the left of a @ */
- while ((strlen(node) > 0) && (haschar(node, '@') > 0))
- strcpy(node, &node[1]);
-
- /* strip anything to the left of a % */
- while ((strlen(node) > 0) && (haschar(node, '%') > 0))
- strcpy(node, &node[1]);
-
- /* reduce multiple system bang paths to node!user */
- while ((strlen(node) > 0) && (haschar(node, '!') > 1))
- strcpy(node, &node[1]);
-
- /* now get rid of the user portion of a node!user string */
- for (a = 0; a < strlen(node); ++a)
- if (node[a] == '!')
- node[a] = 0;
-
-
-
- /* strip leading and trailing spaces in all strings */
- striplt(user);
- striplt(node);
- striplt(name);
}
+
/*
- * Copy line by line, ending at EOF or a "."
+ * send binary to server
*/
-void loopcopy(FILE * to, FILE * from)
+void serv_write(char *buf, int nbytes)
{
- char buf[1024];
- char *r;
-
- while (1) {
- r = fgets(buf, sizeof(buf), from);
- if (r == NULL)
- return;
- strip_trailing_whitespace(buf);
- if (!strcmp(buf, "."))
+ int bytes_written = 0;
+ int retval;
+ while (bytes_written < nbytes) {
+ retval = write(serv_sock, &buf[bytes_written],
+ nbytes - bytes_written);
+ if (retval < 1) {
return;
- fprintf(to, "%s\n", buf);
+ }
+ bytes_written = bytes_written + retval;
}
}
/*
- * pipe message through netproc
+ * input string from socket - implemented in terms of serv_read()
*/
-void do_citmail(char recp[], int dtype)
+void serv_gets(char *buf)
{
-
- time_t now;
- FILE *temp;
- int a;
- int format_type = 0;
- char buf[128];
- char from[512];
- char userbuf[256];
- char frombuf[256];
- char nodebuf[256];
- char destsys[256];
- char subject[256];
- long message_id = 0L;
- char targetroom[256];
- char content_type[256];
- char *extra_headers = NULL;
-
-
- if (dtype == DELIVER_REMOTE) {
-
- /* get the Citadel node name out of the path */
- strncpy(destsys, recp, sizeof(destsys));
- for (a = 0; a < strlen(destsys); ++a) {
- if ((destsys[a] == '!') || (destsys[a] == '.')) {
- destsys[a] = 0;
- }
- }
-
- /* chop the system name out, so we're left with a user */
- while (haschar(recp, '!'))
- strcpy(recp, &recp[1]);
+ int i;
+
+ /* Read one character at a time.
+ */
+ for (i = 0;; i++) {
+ serv_read(&buf[i], 1);
+ if (buf[i] == '\n' || i == 255)
+ break;
}
- /* Convert underscores to spaces */
- for (a = 0; a < strlen(recp); ++a)
- if (recp[a] == '_')
- recp[a] = ' ';
-
- /* Are we delivering to a room instead of a user? */
- if (!strncasecmp(recp, "room ", 5)) {
- strcpy(targetroom, &recp[5]);
- strcpy(recp, "");
- } else {
- strcpy(targetroom, MAILROOM);
- }
-
- time(&now);
- snprintf(from, sizeof from, "postmaster@%s", config.c_nodename);
-
- snprintf(buf, sizeof buf, "./network/spoolin/citmail.%d", getpid());
- temp = fopen(buf, "w");
-
- strcpy(subject, "");
- strcpy(nodebuf, config.c_nodename);
- strcpy(content_type, "text/plain");
-
- do {
- if (fgets(buf, 128, stdin) == NULL)
- strcpy(buf, ".");
- strip_trailing_whitespace(buf);
-
- if (!strncasecmp(buf, "Subject: ", 9))
- strcpy(subject, &buf[9]);
- else if (!strncasecmp(buf, "Date: ", 6)) {
- now = parsedate(&buf[6]);
- if (now < 0L) now = time(NULL);
- }
- else if (!strncasecmp(buf, "From: ", 6))
- strcpy(from, &buf[6]);
- else if (!strncasecmp(buf, "Content-type: ", 14))
- strcpy(content_type, &buf[14]);
- else if (!strncasecmp(buf, "From ", 5)) { /* ignore */
- } else {
- if (extra_headers == NULL) {
- extra_headers = malloc(strlen(buf) + 2);
- strcpy(extra_headers, "");
- } else {
- extra_headers = realloc(extra_headers,
- (strlen(extra_headers) + strlen(buf) + 2));
- }
- strcat(extra_headers, buf);
- strcat(extra_headers, "\n");
- }
- } while ((strcmp(buf, ".")) && (strcmp(buf, "")));
-
- process_rfc822_addr(from, userbuf, nodebuf, frombuf);
-
- if (!strncasecmp(content_type, "text/plain", 10))
- format_type = 1; /* plain ASCII message */
- else
- format_type = 4; /* MIME message */
- /* now convert it to Citadel format */
+ /* If we got a long line, discard characters until the newline.
+ */
+ if (i == 255)
+ while (buf[i] != '\n')
+ serv_read(&buf[i], 1);
- /* Header bytes */
- putc(255, temp); /* 0xFF = start-of-message byte */
- putc(MES_NORMAL, temp); /* Non-anonymous message */
- putc(format_type, temp); /* Format type */
-
- /* Origination */
- fprintf(temp, "P%s@%s%c", userbuf, nodebuf, 0);
- if (message_id)
- fprintf(temp, "I%ld%c", message_id, 0);
- fprintf(temp, "T%ld%c", (long)now, 0);
- fprintf(temp, "A%s%c", userbuf, 0);
-
- /* Destination */
- if (strlen(targetroom) > 0) {
- fprintf(temp, "O%s%c", targetroom, 0);
- } else {
- fprintf(temp, "O%s%c", MAILROOM, 0);
- }
-
- fprintf(temp, "N%s%c", nodebuf, 0);
- fprintf(temp, "H%s%c", frombuf, 0);
- if (dtype == DELIVER_REMOTE) {
- fprintf(temp, "D%s%c", destsys, 0);
- }
- if (strlen(recp) > 0) {
- fprintf(temp, "R%s%c", recp, 0);
- }
- /* Subject and text */
- if (strlen(subject) > 0) {
- fprintf(temp, "U%s%c", subject, 0);
- }
- putc('M', temp);
- if (format_type == 4) {
- fprintf(temp, "Content-type: %s\n", content_type);
- if (extra_headers != NULL)
- fprintf(temp, "%s", extra_headers);
- fprintf(temp, "\n");
- }
- if (extra_headers != NULL)
- free(extra_headers);
- if (strcmp(buf, "."))
- loopcopy(temp, stdin);
- putc(0, temp);
- fclose(temp);
+ /* Strip all trailing nonprintables (crlf)
+ */
+ buf[i] = 0;
+ strip_trailing_nonprint(buf);
}
-void do_uudecode(char *target)
+/*
+ * send line to server - implemented in terms of serv_write()
+ */
+void serv_puts(char *buf)
{
- static char buf[1024];
- FILE *fp;
-
- snprintf(buf, sizeof buf, "cd %s; uudecode", target);
-
- fp = popen(buf, "w");
- if (fp == NULL)
- return;
- while (fgets(buf, 1024, stdin) != NULL) {
- fprintf(fp, "%s", buf);
- }
- pclose(fp);
-
+ /* printf("< %s\n", buf); */
+ serv_write(buf, strlen(buf));
+ serv_write("\n", 1);
}
-int alias(char *name)
-{
- FILE *fp;
- int a;
- char abuf[256];
- fp = fopen(ALIASES, "r");
- if (fp == NULL) {
- syslog(LOG_ERR, "cannot open %s: %s", ALIASES, strerror(errno));
- return (2);
- }
- while (fgets(abuf, 256, fp) != NULL) {
- strip_trailing_whitespace(abuf);
- for (a = 0; a < strlen(abuf); ++a) {
- if (abuf[a] == ',') {
- abuf[a] = 0;
- if (!strcasecmp(name, abuf)) {
- strcpy(name, &abuf[a + 1]);
- }
- }
- }
- }
- fclose(fp);
- return (0);
-}
-void deliver(char recp[], int is_test, int deliver_to_ignet)
-{
- /* various ways we can deliver mail... */
-
- if (deliver_to_ignet) {
- syslog(LOG_NOTICE, "to Citadel network user %s", recp);
- if (is_test == 0)
- do_citmail(recp, DELIVER_REMOTE);
- } else if (!strcmp(recp, "uudecode")) {
- syslog(LOG_NOTICE, "uudecoding to bit bucket directory");
- if (is_test == 0)
- do_uudecode(config.c_bucket_dir);
- } else if (!strcmp(recp, "cit86net")) {
- syslog(LOG_NOTICE, "uudecoding to Cit86net spool");
- if (is_test == 0) {
- do_uudecode(CIT86NET);
- system("exec ./BatchTranslate86");
- }
- } else if (!strcmp(recp, "null")) {
- syslog(LOG_NOTICE, "zapping nulled message");
- } else {
- /* Otherwise, the user is local (or an unknown name was
- * specified, in which case we let netproc handle the bounce)
- */
- syslog(LOG_NOTICE, "to Citadel recipient %s", recp);
- if (is_test == 0)
- do_citmail(recp, DELIVER_LOCAL);
- }
+void cleanup(int exitcode) {
+ char buf[1024];
+ serv_puts("QUIT");
+ serv_gets(buf);
+ fprintf(stderr, "%s\n", buf);
+ exit(exitcode);
}
-int main(int argc, char **argv)
-{
- int is_test = 0;
- int deliver_to_ignet = 0;
- static char recp[1024], buf[1024];
- static char user[1024], node[1024], name[1024];
- int a;
-
- openlog("citmail", LOG_PID, LOG_USER);
- get_config();
- LoadInternetConfig();
-
- if (!strcmp(argv[1], "-t")) {
- is_test = 1;
- syslog(LOG_NOTICE, "test mode - will not deliver");
- }
- if (is_test == 0) {
- strcpy(recp, argv[1]);
- } else {
- strcpy(recp, argv[2]);
- }
-
-/*** Non-SMTP delivery mode ***/
- syslog(LOG_NOTICE, "recp: %s", recp);
- for (a = 0; a < 2; ++a) {
- alias(recp);
- }
-
- /* did we alias it back to a remote address? */
- if ((haschar(recp, '%'))
- || (haschar(recp, '@'))
- || (haschar(recp, '!'))) {
-
- process_rfc822_addr(recp, user, node, name);
- host_alias(node);
-
- /* If there are dots, it's an Internet host, so feed it
- * back to an external mail transport agent such as sendmail.
- */
- if (haschar(node, '.')) {
- snprintf(buf, sizeof buf, SENDMAIL, recp);
- system(buf);
- exit(0);
- }
- /* Otherwise, we're dealing with Citadel mail. */
- else {
- snprintf(recp, sizeof recp, "%s!%s", node, user);
- deliver_to_ignet = 1;
- }
+int main(int argc, char **argv) {
+ char buf[1024];
+ char fromline[1024];
+ FILE *fp;
+ fp = tmpfile();
+ if (fp == NULL) return(errno);
+ sprintf(fromline, "From: someone@somewhere.org");
+ while (fgets(buf, 1024, stdin) != NULL) {
+ fprintf(fp, "%s", buf);
+ if (!strncasecmp(buf, "From:", 5)) strcpy(fromline, buf);
}
- deliver(recp, is_test, deliver_to_ignet);
-
- if (RUN_NETPROC) {
- syslog(LOG_NOTICE, "running netproc");
- if (system("/bin/true") != 0) {
- syslog(LOG_ERR, "netproc failed: %s", strerror(errno));
- }
- } else {
- syslog(LOG_NOTICE, "skipping netproc");
+ strip_trailing_nonprint(fromline);
+
+ sprintf(buf, "%d", SMTP_PORT);
+ serv_sock = connectsock("localhost", buf, "tcp");
+ serv_gets(buf);
+ fprintf(stderr, "%s\n", buf);
+ if (buf[0]!='2') cleanup(1);
+
+ serv_puts("HELO localhost");
+ serv_gets(buf);
+ fprintf(stderr, "%s\n", buf);
+ if (buf[0]!='2') cleanup(1);
+
+ sprintf(buf, "MAIL %s", fromline);
+ serv_puts(buf);
+ serv_gets(buf);
+ fprintf(stderr, "%s\n", buf);
+ if (buf[0]!='2') cleanup(1);
+
+ sprintf(buf, "RCPT To: %s", argv[1]);
+ serv_puts(buf);
+ serv_gets(buf);
+ fprintf(stderr, "%s\n", buf);
+ if (buf[0]!='2') cleanup(1);
+
+ serv_puts("DATA");
+ serv_gets(buf);
+ fprintf(stderr, "%s\n", buf);
+ if (buf[0]!='3') cleanup(1);
+
+ rewind(fp);
+ while (fgets(buf, sizeof buf, fp) != NULL) {
+ strip_trailing_nonprint(buf);
+ serv_puts(buf);
}
- exit(0);
+ serv_puts(".");
+ serv_gets(buf);
+ fprintf(stderr, "%s\n", buf);
+ if (buf[0]!='2') cleanup(1);
+ else cleanup(0);
+ return(0);
}
projects / citadel.git / commitdiff