From: Ken Hornstein <kenh@pobox.com>
Date: Mon, 22 Apr 2019 23:46:17 +0000 (-0400)
Subject: Add basic support for the STLS command in POP
X-Git-Url: https://diplodocus.org/git/nmh/commitdiff_plain/ec173fd2c897f148b4a8e4b9d81743099f1e3b50?ds=sidebyside;hp=77ce4cf16b51da4e873519978a9808bfd83febaa

Add basic support for the STLS command in POP

Add support for the STLS command in POP (sometimes called STARTTLS).
Functionality not yet complete.
---

diff --git a/uip/inc.c b/uip/inc.c
index fecef370..dc49337d 100644
--- a/uip/inc.c
+++ b/uip/inc.c
@@ -96,6 +96,7 @@
     X("sasl", 0, SASLSW) \
     X("nosasl", 0, NOSASLSW) \
     X("saslmech", 0, SASLMECHSW) \
+    X("tls", TLSminc(-3), TLSSW) \
     X("initialtls", TLSminc(-10), INITTLSSW) \
     X("notls", TLSminc(-5), NOTLSSW) \
     X("certverify", TLSminc(-10), CERTVERSW) \
@@ -205,7 +206,8 @@ main (int argc, char **argv)
     int width = -1;
     int hghnum = 0, msgnum = 0;
     FILE *pf = NULL;
-    bool sasl, tls, noverify;
+    bool sasl, noverify;
+    int tls = 0;
     int incerr = 0; /* <0 if inc hits an error which means it should not truncate mailspool */
     char *cp, *maildir = NULL, *folder = NULL;
     char *format = NULL, *form = NULL;
@@ -368,12 +370,16 @@ main (int argc, char **argv)
 		    die("missing argument to %s", argp[-2]);
 		continue;
 
+	    case TLSSW:
+		tls = 1;
+		continue;
+
 	    case INITTLSSW:
-                tls = true;
+                tls = 2;
 		continue;
 
 	    case NOTLSSW:
-                tls = false;
+                tls = 0;
 		continue;
 
 	    case CERTVERSW:
@@ -434,8 +440,10 @@ main (int argc, char **argv)
 	    }
 	}
 
-	if (tls)
-	    tlsflag |= P_INITTLS;
+	if (tls == 1)
+	    tlsflag = P_STARTTLS;
+	else if (tls == 2)
+	    tlsflag = P_INITTLS;
 
 	if (noverify)
 	    tlsflag |= P_NOVERIFY;
diff --git a/uip/popsbr.c b/uip/popsbr.c
index 9ccf6dcc..237e80cc 100644
--- a/uip/popsbr.c
+++ b/uip/popsbr.c
@@ -80,6 +80,58 @@ check_mech(char *server_mechs, size_t server_mechs_size)
     return OK;
 }
 
+/*
+ * If capable, issue the STLS command and start the TLS negotiation
+ */
+
+static int
+pop_start_tls(void)
+{
+    int status;
+    bool stls = false;
+    char *errstr;
+
+    /*
+     * Issue the CAPA command and see if we have the STLS capability
+     */
+
+    if (command("CAPA") == NOTOK) {
+	snprintf(response, sizeof(response),
+		 "The POP CAPA command failed; POP server does not "
+		 "support STLS");
+	return NOTOK;
+    }
+
+    while ((status = multiline()) != DONE) {
+        if (status == NOTOK)
+	    return NOTOK;
+
+	if (strcasecmp(response, "STLS") == 0)
+	    stls = true;
+    }
+
+    if (!stls) {
+	snprintf(response, sizeof(response), "POP server does not support "
+		 "STLS");
+	return NOTOK;
+    }
+
+    /*
+     * Issue STLS and then start the actual TLS negotiation
+     */
+
+    if (command("STLS") == NOTOK)
+    	return NOTOK;
+
+    if (netsec_negotiate_tls(nsc, &errstr) != OK) {
+	snprintf(response, sizeof(response), "%s", errstr);
+	free(errstr);
+	return NOTOK;
+    }
+
+    return OK;
+}
+
 /*
  * Split string containing proxy command into an array of arguments
  * suitable for passing to exec. Returned array must be freed. Shouldn't
@@ -211,17 +263,19 @@ pop_init (char *host, char *port, char *user, char *proxy, int snoop,
     netsec_set_fd(nsc, fd1, fd2);
     netsec_set_snoop(nsc, snoop);
 
-    if (tls & P_INITTLS) {
+    if (tls & P_TLSENABLEMASK) {
 	if (netsec_set_tls(nsc, 1, tls & P_NOVERIFY, &errstr) != OK) {
 	    snprintf(response, sizeof(response), "%s", errstr);
 	    free(errstr);
 	    return NOTOK;
 	}
 
-	if (netsec_negotiate_tls(nsc, &errstr) != OK) {
-	    snprintf(response, sizeof(response), "%s", errstr);
-	    free(errstr);
-	    return NOTOK;
+	if (tls & P_INITTLS) {
+	    if (netsec_negotiate_tls(nsc, &errstr) != OK) {
+		snprintf(response, sizeof(response), "%s", errstr);
+		free(errstr);
+		return NOTOK;
+	    }
 	}
     }
 
@@ -241,6 +295,10 @@ pop_init (char *host, char *port, char *user, char *proxy, int snoop,
 	    if (*response == '+') {
                 nmh_creds_t creds;
 
+		if (tls & P_STARTTLS)
+		    if (pop_start_tls() != OK)
+			return NOTOK;
+
 		if (sasl) {
 		    char server_mechs[256];
 		    if (check_mech(server_mechs, sizeof(server_mechs)) != OK)
diff --git a/uip/popsbr.h b/uip/popsbr.h
index 36ba404e..3e70fe75 100644
--- a/uip/popsbr.h
+++ b/uip/popsbr.h
@@ -5,8 +5,10 @@
  * complete copyright information. */
 
 /* TLS flags */
-#define P_INITTLS 0x01
-#define P_NOVERIFY 0x02
+#define P_STARTTLS 0x01
+#define P_INITTLS 0x02
+#define P_TLSENABLEMASK 0x03
+#define P_NOVERIFY 0x04
 
 int pop_init(char *, char *, char *, char *, int, int, char *, int, const char *);
 int pop_stat(int *, int *);