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/*
Copyright (C) Andrew Tridgell 1998
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
/* support rsync authentication */
#include "rsync.h"
/***************************************************************************
encode a buffer using base64 - simple and slow algorithm. null terminates
the result.
***************************************************************************/
static void base64_encode(char *buf, int len, char *out)
{
char *b64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
int bit_offset, byte_offset, idx, i;
unsigned char *d = (unsigned char *)buf;
int bytes = (len*8 + 5)/6;
memset(out, 0, bytes+1);
for (i=0;i<bytes;i++) {
byte_offset = (i*6)/8;
bit_offset = (i*6)%8;
if (bit_offset < 3) {
idx = (d[byte_offset] >> (2-bit_offset)) & 0x3F;
} else {
idx = (d[byte_offset] << (bit_offset-2)) & 0x3F;
if (byte_offset+1 < len) {
idx |= (d[byte_offset+1] >> (8-(bit_offset-2)));
}
}
out[i] = b64[idx];
}
}
/* create a 16 byte challenge buffer */
static void gen_challenge(char *addr, char *challenge)
{
char input[32];
struct timeval tv;
memset(input, 0, sizeof(input));
strlcpy((char *)input, addr, 16);
gettimeofday(&tv, NULL);
SIVAL(input, 16, tv.tv_sec);
SIVAL(input, 20, tv.tv_usec);
SIVAL(input, 24, getpid());
sum_init();
sum_update(input, sizeof(input));
sum_end(challenge);
}
/* return the secret for a user from the sercret file. maximum length
is len. null terminate it */
static int get_secret(int module, char *user, char *secret, int len)
{
char *fname = lp_secrets_file(module);
int fd, found=0;
char line[MAXPATHLEN];
char *p, *pass=NULL;
if (!fname || !*fname) return 0;
fd = open(fname,O_RDONLY);
if (fd == -1) return 0;
while (!found) {
int i = 0;
memset(line, 0, sizeof(line));
while (i<(sizeof(line)-1)) {
if (read(fd, &line[i], 1) != 1) {
memset(line, 0, sizeof(line));
close(fd);
return 0;
}
if (line[i] == '\r') continue;
if (line[i] == '\n') break;
i++;
}
line[i] = 0;
if (line[0] == '#') continue;
p = strchr(line,':');
if (!p) continue;
*p = 0;
if (strcmp(user, line)) continue;
pass = p+1;
found = 1;
}
close(fd);
if (!found) return 0;
if (strlen(pass) > len-1) {
memset(line, 0, sizeof(line));
return 0;
}
strcpy(secret, pass);
return 1;
}
/* generate a 16 byte hash from a password and challenge */
void generate_hash(char *in, char *challenge, char *out)
{
char buf[16];
sum_init();
sum_update(in, strlen(in));
sum_update(challenge, strlen(challenge));
sum_end(buf);
base64_encode(buf, 16, out);
}
/* possible negotiate authentication with the client. Use "leader" to
start off the auth if necessary */
int auth_server(int fd, int module, char *addr, char *leader)
{
char *users = lp_auth_users(module);
char challenge[16];
char b64_challenge[30];
char line[MAXPATHLEN];
char user[100];
char secret[100];
char pass[30];
char pass2[30];
char *tok;
/* if no auth list then allow anyone in! */
if (!users || !*users) return 1;
gen_challenge(addr, challenge);
base64_encode(challenge, 16, b64_challenge);
io_printf(fd,"%s%s\n", leader, b64_challenge);
if (!read_line(fd, line, sizeof(line)-1)) {
return 0;
}
memset(user, 0, sizeof(user));
memset(pass, 0, sizeof(pass));
if (sscanf(line,"%99s %29s", user, pass) != 2) {
return 0;
}
users = strdup(users);
if (!users) return 0;
for (tok=strtok(users," ,\t"); tok; tok = strtok(NULL," ,\t")) {
if (strcmp(tok, user) == 0) break;
}
free(users);
if (!tok) {
return 0;
}
memset(secret, 0, sizeof(secret));
if (!get_secret(module, user, secret, sizeof(secret)-1)) {
memset(secret, 0, sizeof(secret));
return 0;
}
generate_hash(secret, b64_challenge, pass2);
memset(secret, 0, sizeof(secret));
return (strcmp(pass, pass2) == 0);
}
void auth_client(int fd, char *user, char *challenge)
{
char *pass;
char pass2[30];
if (!user || !*user) return;
if (!(pass=getenv("RSYNC_PASSWORD"))) {
pass = getpass("Password: ");
}
if (!pass || !*pass) {
pass = "";
}
generate_hash(pass, challenge, pass2);
io_printf(fd, "%s %s\n", user, pass2);
}
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