-/* $Cambridge: exim/src/src/auths/dovecot.c,v 1.5 2007/01/24 17:14:27 magnus Exp $ */
-
/*
* Copyright (c) 2004 Andrey Panin <pazke@donpac.ru>
*
* (at your option) any later version.
*/
+/* A number of modifications have been made to the original code. Originally I
+commented them specially, but now they are getting quite extensive, so I have
+ceased doing that. The biggest change is to use unbuffered I/O on the socket
+because using C buffered I/O gives problems on some operating systems. PH */
+
+/* Protocol specifications:
+ * Dovecot 1, protocol version 1.1
+ * http://wiki.dovecot.org/Authentication%20Protocol
+ *
+ * Dovecot 2, protocol version 1.1
+ * http://wiki2.dovecot.org/Design/AuthProtocol
+ */
+
#include "../exim.h"
#include "dovecot.h"
#define VERSION_MAJOR 1
#define VERSION_MINOR 0
+/* http://wiki.dovecot.org/Authentication%20Protocol
+"The maximum line length isn't defined,
+ but it's currently expected to fit into 8192 bytes"
+*/
+#define DOVECOT_AUTH_MAXLINELEN 8192
+
+/* This was hard-coded as 8.
+AUTH req C->S sends {"AUTH", id, mechanism, service } + params, 5 defined for
+Dovecot 1; Dovecot 2 (same protocol version) defines 9.
+
+Master->Server sends {"USER", id, userid} + params, 6 defined.
+Server->Client only gives {"OK", id} + params, unspecified, only 1 guaranteed.
+
+We only define here to accept S->C; max seen is 3+<unspecified>, plus the two
+for the command and id, where unspecified might include _at least_ user=...
+
+So: allow for more fields than we ever expect to see, while aware that count
+can go up without changing protocol version.
+The cost is the length of an array of pointers on the stack.
+*/
+#define DOVECOT_AUTH_MAXFIELDCOUNT 16
+
/* Options specific to the authentication mechanism. */
optionlist auth_dovecot_options[] = {
{
- "server_socket",
- opt_stringptr,
- (void *)(offsetof(auth_dovecot_options_block, server_socket))
+ "server_socket",
+ opt_stringptr,
+ (void *)(offsetof(auth_dovecot_options_block, server_socket))
},
};
/* Size of the options list. An extern variable has to be used so that its
address can appear in the tables drtables.c. */
+
int auth_dovecot_options_count =
sizeof(auth_dovecot_options) / sizeof(optionlist);
/* Default private options block for the authentication method. */
+
auth_dovecot_options_block auth_dovecot_option_defaults = {
NULL, /* server_socket */
};
+
+/* Static variables for reading from the socket */
+
+static uschar sbuffer[256];
+static int socket_buffer_left;
+
+
+
/*************************************************
* Initialization entry point *
*************************************************/
/* Called for each instance, after its options have been read, to
enable consistency checks to be done, or anything else that needs
to be set up. */
+
void auth_dovecot_init(auth_instance *ablock)
{
auth_dovecot_options_block *ob =
ablock->client = FALSE;
}
-static int strcut(char *str, char **ptrs, int nptrs)
+/*************************************************
+ * "strcut" to split apart server lines *
+ *************************************************/
+
+/* Dovecot auth protocol uses TAB \t as delimiter; a line consists
+of a command-name, TAB, and then any parameters, each separated by a TAB.
+A parameter can be param=value or a bool, just param.
+
+This function modifies the original str in-place, inserting NUL characters.
+It initialises ptrs entries, setting all to NULL and only setting
+non-NULL N entries, where N is the return value, the number of fields seen
+(one more than the number of tabs).
+
+Note that the return value will always be at least 1, is the count of
+actual fields (so last valid offset into ptrs is one less).
+*/
+
+static int
+strcut(uschar *str, uschar **ptrs, int nptrs)
{
- char *tmp = str;
+ uschar *last_sub_start = str;
int n;
for (n = 0; n < nptrs; n++)
while (*str) {
if (*str == '\t') {
if (n <= nptrs) {
- *ptrs++ = tmp;
- tmp = str + 1;
- *str = 0;
+ *ptrs++ = last_sub_start;
+ last_sub_start = str + 1;
+ *str = '\0';
}
n++;
}
str++;
}
- if (n < nptrs)
- *ptrs = tmp;
+ /* It's acceptable for the string to end with a tab character. We see
+ this in AUTH PLAIN without an initial response from the client, which
+ causing us to send "334 " and get the data from the client. */
+ if (n <= nptrs) {
+ *ptrs = last_sub_start;
+ } else {
+ HDEBUG(D_auth) debug_printf("dovecot: warning: too many results from tab-splitting; saw %d fields, room for %d\n", n, nptrs);
+ n = nptrs;
+ }
+
+ return n <= nptrs ? n : nptrs;
+}
- return n;
+static void debug_strcut(uschar **ptrs, int nlen, int alen) ARG_UNUSED;
+static void
+debug_strcut(uschar **ptrs, int nlen, int alen)
+{
+ int i;
+ debug_printf("%d read but unreturned bytes; strcut() gave %d results: ",
+ socket_buffer_left, nlen);
+ for (i = 0; i < nlen; i++) {
+ debug_printf(" {%s}", ptrs[i]);
+ }
+ if (nlen < alen)
+ debug_printf(" last is %s\n", ptrs[i] ? ptrs[i] : US"<null>");
+ else
+ debug_printf(" (max for capacity)\n");
}
#define CHECK_COMMAND(str, arg_min, arg_max) do { \
- if (strcasecmp((str), args[0]) != 0) \
+ if (strcmpic(US(str), args[0]) != 0) \
goto out; \
if (nargs - 1 < (arg_min)) \
goto out; \
- if (nargs - 1 > (arg_max)) \
+ if ( (arg_max != -1) && (nargs - 1 > (arg_max)) ) \
goto out; \
} while (0)
/*************************************************
- * Server entry point *
- *************************************************/
+* "fgets" to read directly from socket *
+*************************************************/
+
+/* Added by PH after a suggestion by Steve Usher because the previous use of
+C-style buffered I/O gave trouble. */
+
+static uschar *
+dc_gets(uschar *s, int n, int fd)
+{
+int p = 0;
+int count = 0;
+
+for (;;)
+ {
+ if (socket_buffer_left == 0)
+ {
+ socket_buffer_left = read(fd, sbuffer, sizeof(sbuffer));
+ if (socket_buffer_left == 0) { if (count == 0) return NULL; else break; }
+ p = 0;
+ }
+
+ while (p < socket_buffer_left)
+ {
+ if (count >= n - 1) break;
+ s[count++] = sbuffer[p];
+ if (sbuffer[p++] == '\n') break;
+ }
+
+ memmove(sbuffer, sbuffer + p, socket_buffer_left - p);
+ socket_buffer_left -= p;
+
+ if (s[count-1] == '\n' || count >= n - 1) break;
+ }
+
+s[count] = '\0';
+return s;
+}
+
+
+
+
+/*************************************************
+* Server entry point *
+*************************************************/
int auth_dovecot_server(auth_instance *ablock, uschar *data)
{
auth_dovecot_options_block *ob =
(auth_dovecot_options_block *)(ablock->options_block);
struct sockaddr_un sa;
- char buffer[4096];
- char *args[8];
+ uschar buffer[DOVECOT_AUTH_MAXLINELEN];
+ uschar *args[DOVECOT_AUTH_MAXFIELDCOUNT];
uschar *auth_command;
uschar *auth_extra_data = US"";
+ uschar *p;
int nargs, tmp;
- int cuid = 0, cont = 1, found = 0, fd, ret = DEFER;
- FILE *f;
+ int crequid = 1, cont = 1, fd, ret = DEFER;
+ BOOL found = FALSE;
HDEBUG(D_auth) debug_printf("dovecot authentication\n");
if (connect(fd, (struct sockaddr *) &sa, sizeof(sa)) < 0)
goto out;
- f = fdopen(fd, "a+");
- if (f == NULL)
- goto out;
-
auth_defer_msg = US"authentication socket protocol error";
+ socket_buffer_left = 0; /* Global, used to read more than a line but return by line */
while (cont) {
- if (fgets(buffer, sizeof(buffer), f) == NULL)
+ if (dc_gets(buffer, sizeof(buffer), fd) == NULL)
OUT("authentication socket read error or premature eof");
-
- buffer[strlen(buffer) - 1] = 0;
+ p = buffer + Ustrlen(buffer) - 1;
+ if (*p != '\n') {
+ OUT("authentication socket protocol line too long");
+ }
+ *p = '\0';
HDEBUG(D_auth) debug_printf("received: %s\n", buffer);
nargs = strcut(buffer, args, sizeof(args) / sizeof(args[0]));
-
- switch (toupper(*args[0])) {
- case 'C':
- CHECK_COMMAND("CUID", 1, 1);
- cuid = atoi(args[1]);
- break;
-
- case 'D':
- CHECK_COMMAND("DONE", 0, 0);
- cont = 0;
- break;
-
- case 'M':
- CHECK_COMMAND("MECH", 1, INT_MAX);
- if (strcmpic(US args[1], ablock->public_name) == 0)
- found = 1;
- break;
-
- case 'S':
- CHECK_COMMAND("SPID", 1, 1);
- break;
-
- case 'V':
+ /* HDEBUG(D_auth) debug_strcut(args, nargs, sizeof(args) / sizeof(args[0])); */
+
+ /* Code below rewritten by Kirill Miazine (km@krot.org). Only check commands that
+ Exim will need. Original code also failed if Dovecot server sent unknown
+ command. E.g. COOKIE in version 1.1 of the protocol would cause troubles. */
+ /* pdp: note that CUID is a per-connection identifier sent by the server,
+ which increments at server discretion.
+ By contrast, the "id" field of the protocol is a connection-specific request
+ identifier, which needs to be unique per request from the client and is not
+ connected to the CUID value, so we ignore CUID from server. It's purely for
+ diagnostics. */
+ if (Ustrcmp(args[0], US"VERSION") == 0) {
CHECK_COMMAND("VERSION", 2, 2);
- if (atoi(args[1]) != VERSION_MAJOR)
+ if (Uatoi(args[1]) != VERSION_MAJOR)
OUT("authentication socket protocol version mismatch");
- break;
-
- default:
- goto out;
+ } else if (Ustrcmp(args[0], US"MECH") == 0) {
+ CHECK_COMMAND("MECH", 1, INT_MAX);
+ if (strcmpic(US args[1], ablock->public_name) == 0)
+ found = TRUE;
+ } else if (Ustrcmp(args[0], US"DONE") == 0) {
+ CHECK_COMMAND("DONE", 0, 0);
+ cont = 0;
}
}
- if (!found)
+ if (!found) {
+ auth_defer_msg = string_sprintf("Dovecot did not advertise mechanism \"%s\" to us", ablock->public_name);
goto out;
+ }
/* Added by PH: data must not contain tab (as it is
b64 it shouldn't, but check for safety). */
/* Added by PH: extra fields when TLS is in use or if the TCP/IP
connection is local. */
- if (tls_cipher != NULL)
+ if (tls_in.cipher != NULL)
auth_extra_data = string_sprintf("secured\t%s%s",
- tls_certificate_verified? "valid-client-cert" : "",
- tls_certificate_verified? "\t" : "");
- else if (interface_address
- && Ustrcmp(sender_host_address, interface_address) == 0)
+ tls_in.certificate_verified? "valid-client-cert" : "",
+ tls_in.certificate_verified? "\t" : "");
+ else if (interface_address != NULL &&
+ Ustrcmp(sender_host_address, interface_address) == 0)
auth_extra_data = US"secured\t";
****************************************************************************/
auth_command = string_sprintf("VERSION\t%d\t%d\nCPID\t%d\n"
- "AUTH\t%d\t%s\tservice=smtp\t%srip=%s\tlip=%s\tresp=%s\n",
- VERSION_MAJOR, VERSION_MINOR, getpid(), cuid,
+ "AUTH\t%d\t%s\tservice=smtp\t%srip=%s\tlip=%s\tnologin\tresp=%s\n",
+ VERSION_MAJOR, VERSION_MINOR, getpid(), crequid,
ablock->public_name, auth_extra_data, sender_host_address,
interface_address, data ? (char *) data : "");
- fprintf(f, "%s", auth_command);
+ if (write(fd, auth_command, Ustrlen(auth_command)) < 0)
+ HDEBUG(D_auth) debug_printf("error sending auth_command: %s\n",
+ strerror(errno));
+
HDEBUG(D_auth) debug_printf("sent: %s", auth_command);
while (1) {
- if (fgets(buffer, sizeof(buffer), f) == NULL) {
+ uschar *temp;
+ uschar *auth_id_pre = NULL;
+ int i;
+
+ if (dc_gets(buffer, sizeof(buffer), fd) == NULL) {
auth_defer_msg = US"authentication socket read error or premature eof";
goto out;
}
- buffer[strlen(buffer) - 1] = 0;
+ buffer[Ustrlen(buffer) - 1] = 0;
HDEBUG(D_auth) debug_printf("received: %s\n", buffer);
nargs = strcut(buffer, args, sizeof(args) / sizeof(args[0]));
- if (atoi(args[1]) != cuid)
+ if (Uatoi(args[1]) != crequid)
OUT("authentication socket connection id mismatch");
switch (toupper(*args[0])) {
goto out;
}
- if (fprintf(f, "CONT\t%d\t%s\r\n", cuid, data) < 0)
+ temp = string_sprintf("CONT\t%d\t%s\n", crequid, data);
+ if (write(fd, temp, Ustrlen(temp)) < 0)
OUT("authentication socket write error");
-
break;
case 'F':
- CHECK_COMMAND("FAIL", 1, 2);
+ CHECK_COMMAND("FAIL", 1, -1);
- /* FIXME: add proper response handling */
- if (args[2]) {
- uschar *p = US strchr(args[2], '=');
- if (p) {
- ++p;
+ for (i=2; (i<nargs) && (auth_id_pre == NULL); i++)
+ {
+ if ( Ustrncmp(args[i], US"user=", 5) == 0 )
+ {
+ auth_id_pre = args[i]+5;
expand_nstring[1] = auth_vars[0] =
- string_copy(p); /* PH */
- expand_nlength[1] = Ustrlen(p);
+ string_copy(auth_id_pre); /* PH */
+ expand_nlength[1] = Ustrlen(auth_id_pre);
expand_nmax = 1;
}
}
goto out;
case 'O':
- CHECK_COMMAND("OK", 2, 2);
+ CHECK_COMMAND("OK", 2, -1);
+
+ /*
+ * Search for the "user=$USER" string in the args array
+ * and return the proper value.
+ */
+ for (i=2; (i<nargs) && (auth_id_pre == NULL); i++)
{
- /* FIXME: add proper response handling */
- uschar *p = US strchr(args[2], '=');
- if (!p)
- OUT("authentication socket protocol error, username missing");
-
- p++;
- expand_nstring[1] = auth_vars[0] =
- string_copy(p); /* PH */
- expand_nlength[1] = Ustrlen(p);
- expand_nmax = 1;
+ if ( Ustrncmp(args[i], US"user=", 5) == 0 )
+ {
+ auth_id_pre = args[i]+5;
+ expand_nstring[1] = auth_vars[0] =
+ string_copy(auth_id_pre); /* PH */
+ expand_nlength[1] = Ustrlen(auth_id_pre);
+ expand_nmax = 1;
+ }
}
+
+ if (auth_id_pre == NULL)
+ OUT("authentication socket protocol error, username missing");
+
ret = OK;
/* fallthrough */
}
}
-out: close(fd);
+out:
+ /* close the socket used by dovecot */
+ if (fd >= 0)
+ close(fd);
/* Expand server_condition as an authorization check */
return (ret == OK)? auth_check_serv_cond(ablock) : ret;
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