EXPORTED struct backend *backend_connect(struct backend *ret_backend, const char *server,
struct protocol_t *prot, const char *userid,
sasl_callback_t *cb, const char **auth_status,
int logfd)
{
/* need to (re)establish connection to server or create one */
int sock = -1;
int r;
int err = -1;
int do_tls = 0;
int noauth = 0;
struct addrinfo hints, *res0 = NULL, *res;
struct sockaddr_un sunsock;
struct backend *ret;
if (!ret_backend) {
ret = xzmalloc(sizeof(struct backend));
strlcpy(ret->hostname, server, sizeof(ret->hostname));
ret->timeout = NULL;
}
else
ret = ret_backend;
if (server[0] == '/') { /* unix socket */
res0 = &hints;
memset(res0, 0, sizeof(struct addrinfo));
res0->ai_family = PF_UNIX;
res0->ai_socktype = SOCK_STREAM;
res0->ai_addr = (struct sockaddr *) &sunsock;
res0->ai_addrlen = sizeof(sunsock.sun_family) + strlen(server) + 1;
#ifdef SIN6_LEN
res0->ai_addrlen += sizeof(sunsock.sun_len);
sunsock.sun_len = res0->ai_addrlen;
#endif
sunsock.sun_family = AF_UNIX;
strlcpy(sunsock.sun_path, server, sizeof(sunsock.sun_path));
if (!strcmp(prot->sasl_service, "lmtp") ||
!strcmp(prot->sasl_service, "csync")) {
noauth = 1;
}
}
else { /* inet socket */
char host[1024], *p;
const char *service = prot->service;
/* Parse server string for possible port and options */
strlcpy(host, server, sizeof(host));
if ((p = strchr(host, ':'))) {
*p++ = '\0';
service = p;
if ((p = strchr(service, '/'))) {
tok_t tok;
char *opt;
*p++ = '\0';
tok_initm(&tok, p, "/", 0);
while ((opt = tok_next(&tok))) {
if (!strcmp(opt, "tls")) do_tls = 1;
else if (!strcmp(opt, "noauth")) noauth = 1;
}
tok_fini(&tok);
}
}
memset(&hints, 0, sizeof(hints));
hints.ai_family = PF_UNSPEC;
hints.ai_socktype = SOCK_STREAM;
err = getaddrinfo(host, service, &hints, &res0);
if (err) {
syslog(LOG_ERR, "getaddrinfo(%s) failed: %s",
server, gai_strerror(err));
goto error;
}
}
for (res = res0; res; res = res->ai_next) {
sock = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
if (sock < 0)
continue;
/* Do a non-blocking connect() */
nonblock(sock, 1);
if (!connect(sock, res->ai_addr, res->ai_addrlen)) {
/* connect() succeeded immediately */
break;
}
else if (errno == EINPROGRESS) {
/* connect() in progress */
int n;
fd_set wfds, rfds;
time_t now = time(NULL);
time_t timeout = now + config_getint(IMAPOPT_CLIENT_TIMEOUT);
struct timeval waitfor;
/* select() socket for writing until we succeed, fail, or timeout */
do {
FD_ZERO(&wfds);
FD_SET(sock, &wfds);
rfds = wfds;
waitfor.tv_sec = timeout - now;
waitfor.tv_usec = 0;
n = select(sock + 1, &rfds, &wfds, NULL, &waitfor);
now = time(NULL);
/* Retry select() if interrupted */
} while (n < 0 && errno == EINTR && now < timeout);
if (!n) {
/* select() timed out */
errno = ETIMEDOUT;
}
else if (FD_ISSET(sock, &rfds) || FD_ISSET(sock, &wfds)) {
/* Socket is ready for I/O - get SO_ERROR to determine status */
socklen_t errlen = sizeof(err);
if (!getsockopt(sock, SOL_SOCKET, SO_ERROR, &err, &errlen) &&
!(errno = err)) {
/* connect() succeeded */
break;
}
}
}
close(sock);
sock = -1;
}
if (sock < 0) {
if (res0 != &hints) freeaddrinfo(res0);
syslog(LOG_ERR, "connect(%s) failed: %m", server);
goto error;
}
/* Reset socket to blocking */
nonblock(sock, 0);
memcpy(&ret->addr, res->ai_addr, res->ai_addrlen);
if (res0 != &hints)
freeaddrinfo(res0);
ret->in = prot_new(sock, 0);
ret->out = prot_new(sock, 1);
ret->sock = sock;
prot_settimeout(ret->in, config_getint(IMAPOPT_CLIENT_TIMEOUT));
prot_setflushonread(ret->in, ret->out);
ret->prot = prot;
/* use literal+ to send literals */
prot_setisclient(ret->in, 1);
prot_setisclient(ret->out, 1);
/* Start TLS if required */
if (do_tls) r = backend_starttls(ret, NULL, NULL, NULL);
/* Login to the server */
if (prot->type == TYPE_SPEC)
r = prot->u.spec.login(ret, userid, cb, auth_status, noauth);
else
r = backend_login(ret, userid, cb, auth_status, noauth);
if (r) goto error;
if (logfd >= 0) {
prot_setlog(ret->in, logfd);
prot_setlog(ret->out, logfd);
}
else prot_settimeout(ret->in, 0);
return ret;
error:
forget_capabilities(ret);
if (ret->in) {
prot_free(ret->in);
ret->in = NULL;
}
if (ret->out) {
prot_free(ret->out);
ret->out = NULL;
}
if (sock >= 0)
close(sock);
if (ret->saslconn) {
sasl_dispose(&ret->saslconn);
ret->saslconn = NULL;
}
if (!ret_backend)
free(ret);
return NULL;
}
static int login(struct backend *s, const char *userid,
sasl_callback_t *cb, const char **status,
int noauth __attribute__((unused)))
{
int r = 0;
socklen_t addrsize;
struct sockaddr_storage saddr_l, saddr_r;
char remoteip[60], localip[60];
static struct buf buf = BUF_INITIALIZER;
sasl_security_properties_t secprops =
{ 0, 0xFF, PROT_BUFSIZE, 0, NULL, NULL }; /* default secprops */
const char *mech_conf, *pass, *clientout = NULL;
struct auth_scheme_t *scheme = NULL;
unsigned need_tls = 0, tls_done = 0, auth_done = 0, clientoutlen;
hdrcache_t hdrs = NULL;
if (status) *status = NULL;
/* set the IP addresses */
addrsize = sizeof(struct sockaddr_storage);
if (getpeername(s->sock, (struct sockaddr *) &saddr_r, &addrsize) ||
iptostring((struct sockaddr *) &saddr_r, addrsize, remoteip, 60)) {
if (status) *status = "Failed to get remote IP address";
return SASL_FAIL;
}
addrsize = sizeof(struct sockaddr_storage);
if (getsockname(s->sock, (struct sockaddr *) &saddr_l, &addrsize) ||
iptostring((struct sockaddr *) &saddr_l, addrsize, localip, 60)) {
if (status) *status = "Failed to get local IP address";
return SASL_FAIL;
}
/* Create callbacks, if necessary */
if (!cb) {
buf_setmap(&buf, s->hostname, strcspn(s->hostname, "."));
buf_appendcstr(&buf, "_password");
pass = config_getoverflowstring(buf_cstring(&buf), NULL);
if (!pass) pass = config_getstring(IMAPOPT_PROXY_PASSWORD);
cb = mysasl_callbacks(NULL, /* userid */
config_getstring(IMAPOPT_PROXY_AUTHNAME),
config_getstring(IMAPOPT_PROXY_REALM),
pass);
s->sasl_cb = cb;
}
/* Create SASL context */
r = sasl_client_new(s->prot->sasl_service, s->hostname,
localip, remoteip, cb, SASL_USAGE_FLAGS, &s->saslconn);
if (r != SASL_OK) goto done;
r = sasl_setprop(s->saslconn, SASL_SEC_PROPS, &secprops);
if (r != SASL_OK) goto done;
/* Get SASL mechanism list. We can force a particular
mechanism using a <shorthost>_mechs option */
buf_setmap(&buf, s->hostname, strcspn(s->hostname, "."));
buf_appendcstr(&buf, "_mechs");
if (!(mech_conf = config_getoverflowstring(buf_cstring(&buf), NULL))) {
mech_conf = config_getstring(IMAPOPT_FORCE_SASL_CLIENT_MECH);
}
do {
unsigned code;
const char **hdr, *errstr, *serverin;
char base64[BASE64_BUF_SIZE+1];
unsigned int serverinlen;
struct body_t resp_body;
#ifdef SASL_HTTP_REQUEST
sasl_http_request_t httpreq = { "OPTIONS", /* Method */
"*", /* URI */
(u_char *) "", /* Empty body */
0, /* Zero-length body */
0 }; /* Persistent cxn? */
#endif
/* Base64 encode any client response, if necessary */
if (clientout && scheme && (scheme->flags & AUTH_BASE64)) {
r = sasl_encode64(clientout, clientoutlen,
base64, BASE64_BUF_SIZE, &clientoutlen);
if (r != SASL_OK) break;
clientout = base64;
}
/* Send Authorization and/or Upgrade request to server */
prot_puts(s->out, "OPTIONS * HTTP/1.1\r\n");
prot_printf(s->out, "Host: %s\r\n", s->hostname);
prot_printf(s->out, "User-Agent: %s\r\n", buf_cstring(&serverinfo));
if (scheme) {
prot_printf(s->out, "Authorization: %s %s\r\n",
scheme->name, clientout ? clientout : "");
prot_printf(s->out, "Authorize-As: %s\r\n",
userid ? userid : "anonymous");
}
else {
prot_printf(s->out, "Upgrade: %s\r\n", TLS_VERSION);
if (need_tls) {
prot_puts(s->out, "Connection: Upgrade\r\n");
need_tls = 0;
}
prot_puts(s->out, "Authorization: \r\n");
}
prot_puts(s->out, "\r\n");
prot_flush(s->out);
serverin = clientout = NULL;
serverinlen = clientoutlen = 0;
/* Read response(s) from backend until final response or error */
do {
resp_body.flags = BODY_DISCARD;
r = http_read_response(s, METH_OPTIONS, &code, NULL,
&hdrs, &resp_body, &errstr);
if (r) {
if (status) *status = errstr;
break;
}
if (code == 101) { /* Switching Protocols */
if (tls_done) {
r = HTTP_BAD_GATEWAY;
if (status) *status = "TLS already active";
break;
}
else if (backend_starttls(s, NULL, NULL, NULL)) {
r = HTTP_SERVER_ERROR;
if (status) *status = "Unable to start TLS";
break;
}
else tls_done = 1;
}
} while (code < 200);
switch (code) {
default: /* Failure */
if (!r) {
r = HTTP_BAD_GATEWAY;
if (status) {
buf_reset(&buf);
buf_printf(&buf,
"Unexpected status code from backend: %u", code);
*status = buf_cstring(&buf);
}
}
break;
case 426: /* Upgrade Required */
if (tls_done) {
r = HTTP_BAD_GATEWAY;
if (status) *status = "TLS already active";
}
else need_tls = 1;
break;
case 200: /* OK */
if (scheme->recv_success &&
(serverin = scheme->recv_success(hdrs))) {
/* Process success data */
serverinlen = strlen(serverin);
goto challenge;
}
break;
case 401: /* Unauthorized */
if (auth_done) {
r = SASL_BADAUTH;
break;
}
if (!serverin) {
int i = 0;
hdr = spool_getheader(hdrs, "WWW-Authenticate");
if (!scheme) {
unsigned avail_auth_schemes = 0;
const char *mech = NULL;
size_t len;
/* Compare authentication schemes offered in
* WWW-Authenticate header(s) to what we support */
buf_reset(&buf);
for (i = 0; hdr && hdr[i]; i++) {
len = strcspn(hdr[i], " ");
for (scheme = auth_schemes; scheme->name; scheme++) {
if (!strncmp(scheme->name, hdr[i], len) &&
!((scheme->flags & AUTH_NEED_PERSIST) &&
(resp_body.flags & BODY_CLOSE))) {
/* Tag the scheme as available */
avail_auth_schemes |= (1 << scheme->idx);
/* Add SASL-based schemes to SASL mech list */
if (scheme->saslmech) {
if (buf_len(&buf)) buf_putc(&buf, ' ');
buf_appendcstr(&buf, scheme->saslmech);
}
break;
}
}
}
/* If we have a mech_conf, use it */
if (mech_conf && buf_len(&buf)) {
char *conf = xstrdup(mech_conf);
char *newmechlist =
intersect_mechlists(conf,
(char *) buf_cstring(&buf));
if (newmechlist) {
buf_setcstr(&buf, newmechlist);
free(newmechlist);
}
else {
syslog(LOG_DEBUG, "%s did not offer %s",
s->hostname, mech_conf);
buf_reset(&buf);
}
free(conf);
}
#ifdef SASL_HTTP_REQUEST
/* Set HTTP request as specified above (REQUIRED) */
httpreq.non_persist = (resp_body.flags & BODY_CLOSE);
sasl_setprop(s->saslconn, SASL_HTTP_REQUEST, &httpreq);
#endif
/* Try to start SASL exchange using available mechs */
r = sasl_client_start(s->saslconn, buf_cstring(&buf),
NULL, /* no prompts */
NULL, NULL, /* no initial resp */
&mech);
if (mech) {
/* Find auth scheme associated with chosen SASL mech */
for (scheme = auth_schemes; scheme->name; scheme++) {
if (scheme->saslmech &&
!strcmp(scheme->saslmech, mech)) break;
}
}
else {
/* No matching SASL mechs - try Basic */
scheme = &auth_schemes[AUTH_BASIC];
if (!(avail_auth_schemes & (1 << scheme->idx))) {
need_tls = !tls_done;
break; /* case 401 */
}
}
/* Find the associated WWW-Authenticate header */
for (i = 0; hdr && hdr[i]; i++) {
len = strcspn(hdr[i], " ");
if (!strncmp(scheme->name, hdr[i], len)) break;
}
}
/* Get server challenge, if any */
if (hdr) {
const char *p = strchr(hdr[i], ' ');
serverin = p ? ++p : "";
serverinlen = strlen(serverin);
}
}
challenge:
if (serverin) {
/* Perform the next step in the auth exchange */
if (scheme->idx == AUTH_BASIC) {
/* Don't care about "realm" in server challenge */
const char *authid =
callback_getdata(s->saslconn, cb, SASL_CB_AUTHNAME);
pass = callback_getdata(s->saslconn, cb, SASL_CB_PASS);
buf_reset(&buf);
buf_printf(&buf, "%s:%s", authid, pass);
clientout = buf_cstring(&buf);
clientoutlen = buf_len(&buf);
auth_done = 1;
}
else {
/* Base64 decode any server challenge, if necessary */
if (serverin && (scheme->flags & AUTH_BASE64)) {
r = sasl_decode64(serverin, serverinlen,
base64, BASE64_BUF_SIZE, &serverinlen);
if (r != SASL_OK) break; /* case 401 */
serverin = base64;
}
/* SASL mech (Digest, Negotiate, NTLM) */
r = sasl_client_step(s->saslconn, serverin, serverinlen,
NULL, /* no prompts */
&clientout, &clientoutlen);
if (r == SASL_OK) auth_done = 1;
}
}
break; /* case 401 */
}
} while (need_tls || clientout);
done:
if (hdrs) spool_free_hdrcache(hdrs);
if (r && status && !*status) *status = sasl_errstring(r, NULL, NULL);
return r;
}
static int backend_authenticate(struct backend *s, const char *userid,
sasl_callback_t *cb, const char **status)
{
struct protocol_t *prot = s->prot;
int r;
char *mechlist;
sasl_security_properties_t secprops =
{ 0, 0xFF, PROT_BUFSIZE, 0, NULL, NULL }; /* default secprops */
struct sockaddr_storage saddr_l, saddr_r;
char remoteip[60], localip[60];
socklen_t addrsize;
char buf[2048], optstr[128], *p;
const char *mech_conf, *pass;
if (prot->type != TYPE_STD) return SASL_FAIL;
/* set the IP addresses */
addrsize = sizeof(struct sockaddr_storage);
if (getpeername(s->sock, (struct sockaddr *)&saddr_r, &addrsize) != 0)
return SASL_FAIL;
if (iptostring((struct sockaddr *)&saddr_r, addrsize, remoteip, 60) != 0)
return SASL_FAIL;
addrsize = sizeof(struct sockaddr_storage);
if (getsockname(s->sock, (struct sockaddr *)&saddr_l, &addrsize)!=0)
return SASL_FAIL;
if (iptostring((struct sockaddr *)&saddr_l, addrsize, localip, 60) != 0)
return SASL_FAIL;
if (!cb) {
strlcpy(optstr, s->hostname, sizeof(optstr));
p = strchr(optstr, '.');
if (p) *p = '\0';
strlcat(optstr, "_password", sizeof(optstr));
pass = config_getoverflowstring(optstr, NULL);
if(!pass) pass = config_getstring(IMAPOPT_PROXY_PASSWORD);
cb = mysasl_callbacks(userid,
config_getstring(IMAPOPT_PROXY_AUTHNAME),
config_getstring(IMAPOPT_PROXY_REALM),
pass);
s->sasl_cb = cb;
}
/* Require proxying if we have an "interesting" userid (authzid) */
r = sasl_client_new(prot->sasl_service, s->hostname, localip, remoteip, cb,
(userid && *userid ? SASL_NEED_PROXY : 0) |
(prot->u.std.sasl_cmd.parse_success ? SASL_SUCCESS_DATA : 0),
&s->saslconn);
if (r != SASL_OK) return r;
r = sasl_setprop(s->saslconn, SASL_SEC_PROPS, &secprops);
if (r != SASL_OK) return r;
/* Get SASL mechanism list. We can force a particular
mechanism using a <shorthost>_mechs option */
strcpy(buf, s->hostname);
p = strchr(buf, '.');
if (p) *p = '\0';
strcat(buf, "_mechs");
mech_conf = config_getoverflowstring(buf, NULL);
if (!mech_conf)
mech_conf = config_getstring(IMAPOPT_FORCE_SASL_CLIENT_MECH);
#ifdef HAVE_SSL
strlcpy(optstr, s->hostname, sizeof(optstr));
p = strchr(optstr, '.');
if (p) *p = '\0';
strlcat(optstr, "_client_cert", sizeof(optstr));
const char *c_cert_file = config_getoverflowstring(optstr, NULL);
if (!c_cert_file) {
c_cert_file = config_getstring(IMAPOPT_TLS_CLIENT_CERT);
}
strlcpy(optstr, s->hostname, sizeof(optstr));
p = strchr(optstr, '.');
if (p) *p = '\0';
strlcat(optstr, "_client_key", sizeof(optstr));
const char *c_key_file = config_getoverflowstring(optstr, NULL);
if (!c_key_file) {
c_key_file = config_getstring(IMAPOPT_TLS_CLIENT_KEY);
}
#else
const char *c_cert_file = NULL;
const char *c_key_file = NULL;
#endif
mechlist = backend_get_cap_params(s, CAPA_AUTH);
do {
/* If we have a mech_conf, use it */
if (mech_conf && mechlist) {
char *conf = xstrdup(mech_conf);
char *newmechlist = intersect_mechlists( conf, mechlist );
if ( newmechlist == NULL ) {
syslog( LOG_INFO, "%s did not offer %s", s->hostname,
mech_conf );
}
free(conf);
free(mechlist);
mechlist = newmechlist;
}
if (mechlist) {
/* we now do the actual SASL exchange */
saslclient(s->saslconn, &prot->u.std.sasl_cmd, mechlist,
s->in, s->out, &r, status);
/* garbage collect */
free(mechlist);
mechlist = NULL;
}
else r = SASL_NOMECH;
/* If we don't have a usable mech, do TLS and try again */
} while (r == SASL_NOMECH && CAPA(s, CAPA_STARTTLS) &&
backend_starttls(s, &prot->u.std.tls_cmd, c_cert_file, c_key_file) != -1 &&
(mechlist = backend_get_cap_params(s, CAPA_AUTH)));
if (r == SASL_OK) {
prot_setsasl(s->in, s->saslconn);
prot_setsasl(s->out, s->saslconn);
}
if (mechlist) free(mechlist);
return SASL_OK;
}
