diff --git a/putty.h b/putty.h
index a96230f2..a8cfcf27 100644
--- a/putty.h
+++ b/putty.h
@@ -706,9 +706,9 @@ char *get_ttymode(void *frontend, const char *mode);
 /*
  * >0 = `got all results, carry on'
  * 0  = `user cancelled' (FIXME distinguish "give up entirely" and "next auth"?)
- * <0 = `please call back later with more in/inlen'
+ * <0 = `please call back later with a fuller bufchain'
  */
-int get_userpass_input(prompts_t *p, const unsigned char *in, int inlen);
+int get_userpass_input(prompts_t *p, bufchain *input);
 #define OPTIMISE_IS_SCROLL 1
 
 void set_iconic(void *frontend, int iconic);
@@ -1119,8 +1119,7 @@ void term_provide_resize_fn(Terminal *term,
 void term_provide_logctx(Terminal *term, void *logctx);
 void term_set_focus(Terminal *term, int has_focus);
 char *term_get_ttymode(Terminal *term, const char *mode);
-int term_get_userpass_input(Terminal *term, prompts_t *p,
-			    const unsigned char *in, int inlen);
+int term_get_userpass_input(Terminal *term, prompts_t *p, bufchain *input);
 
 int format_arrow_key(char *buf, Terminal *term, int xkey, int ctrl);
 
diff --git a/rlogin.c b/rlogin.c
index ff2c0a8f..cd6260d2 100644
--- a/rlogin.c
+++ b/rlogin.c
@@ -230,7 +230,7 @@ static const char *rlogin_init(void *frontend_handle, void **backend_handle,
         rlogin->prompt->to_server = TRUE;
         rlogin->prompt->name = dupstr("Rlogin login name");
         add_prompt(rlogin->prompt, dupstr("rlogin username: "), TRUE); 
-        ret = get_userpass_input(rlogin->prompt, NULL, 0);
+        ret = get_userpass_input(rlogin->prompt, NULL);
         if (ret >= 0) {
             rlogin_startup(rlogin, rlogin->prompt->prompts[0]->result);
         }
@@ -264,26 +264,39 @@ static void rlogin_reconfig(void *handle, Conf *conf)
 static int rlogin_send(void *handle, const char *buf, int len)
 {
     Rlogin rlogin = (Rlogin) handle;
+    bufchain bc;
 
     if (rlogin->s == NULL)
 	return 0;
 
+    bufchain_init(&bc);
+    bufchain_add(&bc, buf, len);
+
     if (rlogin->prompt) {
         /*
          * We're still prompting for a username, and aren't talking
          * directly to the network connection yet.
          */
-        int ret = get_userpass_input(rlogin->prompt,
-                                     (unsigned char *)buf, len);
+        int ret = get_userpass_input(rlogin->prompt, &bc);
         if (ret >= 0) {
             rlogin_startup(rlogin, rlogin->prompt->prompts[0]->result);
             /* that nulls out rlogin->prompt, so then we'll start sending
              * data down the wire in the obvious way */
         }
-    } else {
-        rlogin->bufsize = sk_write(rlogin->s, buf, len);
     }
 
+    if (!rlogin->prompt) {
+        while (bufchain_size(&bc) > 0) {
+            void *data;
+            int len;
+            bufchain_prefix(&bc, &data, &len);
+            rlogin->bufsize = sk_write(rlogin->s, data, len);
+            bufchain_consume(&bc, len);
+        }
+    }
+
+    bufchain_clear(&bc);
+
     return rlogin->bufsize;
 }
 
diff --git a/ssh.c b/ssh.c
index 59c3046d..8665ad2a 100644
--- a/ssh.c
+++ b/ssh.c
@@ -4497,11 +4497,15 @@ static int do_ssh1_login(Ssh ssh, const unsigned char *in, int inlen,
 	    s->cur_prompt->to_server = TRUE;
 	    s->cur_prompt->name = dupstr("SSH login name");
 	    add_prompt(s->cur_prompt, dupstr("login as: "), TRUE);
-	    ret = get_userpass_input(s->cur_prompt, NULL, 0);
+	    ret = get_userpass_input(s->cur_prompt, NULL);
 	    while (ret < 0) {
+                bufchain tmp_user_input;
 		ssh->send_ok = 1;
 		crWaitUntil(!pktin);
-		ret = get_userpass_input(s->cur_prompt, in, inlen);
+                bufchain_init(&tmp_user_input);
+                bufchain_add(&tmp_user_input, in, inlen);
+		ret = get_userpass_input(s->cur_prompt, &tmp_user_input);
+                bufchain_clear(&tmp_user_input);
 		ssh->send_ok = 0;
 	    }
 	    if (!ret) {
@@ -4804,11 +4808,16 @@ static int do_ssh1_login(Ssh ssh, const unsigned char *in, int inlen,
 		    add_prompt(s->cur_prompt,
 			       dupprintf("Passphrase for key \"%.100s\": ",
 					 s->publickey_comment), FALSE);
-		    ret = get_userpass_input(s->cur_prompt, NULL, 0);
+		    ret = get_userpass_input(s->cur_prompt, NULL);
 		    while (ret < 0) {
+                        bufchain tmp_user_input;
 			ssh->send_ok = 1;
 			crWaitUntil(!pktin);
-			ret = get_userpass_input(s->cur_prompt, in, inlen);
+                        bufchain_init(&tmp_user_input);
+                        bufchain_add(&tmp_user_input, in, inlen);
+                        ret = get_userpass_input(s->cur_prompt,
+                                                 &tmp_user_input);
+                        bufchain_clear(&tmp_user_input);
 			ssh->send_ok = 0;
 		    }
 		    if (!ret) {
@@ -5024,11 +5033,15 @@ static int do_ssh1_login(Ssh ssh, const unsigned char *in, int inlen,
 	 */
 	{
 	    int ret; /* need not be kept over crReturn */
-	    ret = get_userpass_input(s->cur_prompt, NULL, 0);
+	    ret = get_userpass_input(s->cur_prompt, NULL);
 	    while (ret < 0) {
+                bufchain tmp_user_input;
 		ssh->send_ok = 1;
 		crWaitUntil(!pktin);
-		ret = get_userpass_input(s->cur_prompt, in, inlen);
+                bufchain_init(&tmp_user_input);
+                bufchain_add(&tmp_user_input, in, inlen);
+		ret = get_userpass_input(s->cur_prompt, &tmp_user_input);
+                bufchain_clear(&tmp_user_input);
 		ssh->send_ok = 0;
 	    }
 	    if (!ret) {
@@ -10313,11 +10326,15 @@ static void do_ssh2_authconn(Ssh ssh, const unsigned char *in, int inlen,
 	    s->cur_prompt->to_server = TRUE;
 	    s->cur_prompt->name = dupstr("SSH login name");
 	    add_prompt(s->cur_prompt, dupstr("login as: "), TRUE); 
-	    ret = get_userpass_input(s->cur_prompt, NULL, 0);
+	    ret = get_userpass_input(s->cur_prompt, NULL);
 	    while (ret < 0) {
+                bufchain tmp_user_input;
 		ssh->send_ok = 1;
 		crWaitUntilV(!pktin);
-		ret = get_userpass_input(s->cur_prompt, in, inlen);
+                bufchain_init(&tmp_user_input);
+                bufchain_add(&tmp_user_input, in, inlen);
+		ret = get_userpass_input(s->cur_prompt, &tmp_user_input);
+                bufchain_clear(&tmp_user_input);
 		ssh->send_ok = 0;
 	    }
 	    if (!ret) {
@@ -10749,12 +10766,16 @@ static void do_ssh2_authconn(Ssh ssh, const unsigned char *in, int inlen,
 				   dupprintf("Passphrase for key \"%.100s\": ",
 					     s->publickey_comment),
 				   FALSE);
-			ret = get_userpass_input(s->cur_prompt, NULL, 0);
+			ret = get_userpass_input(s->cur_prompt, NULL);
 			while (ret < 0) {
+                            bufchain tmp_user_input;
 			    ssh->send_ok = 1;
 			    crWaitUntilV(!pktin);
-			    ret = get_userpass_input(s->cur_prompt,
-						     in, inlen);
+                            bufchain_init(&tmp_user_input);
+                            bufchain_add(&tmp_user_input, in, inlen);
+                            ret = get_userpass_input(s->cur_prompt,
+                                                     &tmp_user_input);
+                            bufchain_clear(&tmp_user_input);
 			    ssh->send_ok = 0;
 			}
 			if (!ret) {
@@ -11135,11 +11156,16 @@ static void do_ssh2_authconn(Ssh ssh, const unsigned char *in, int inlen,
 		     */
 		    {
 			int ret; /* not live over crReturn */
-			ret = get_userpass_input(s->cur_prompt, NULL, 0);
+			ret = get_userpass_input(s->cur_prompt, NULL);
 			while (ret < 0) {
+                            bufchain tmp_user_input;
 			    ssh->send_ok = 1;
 			    crWaitUntilV(!pktin);
-			    ret = get_userpass_input(s->cur_prompt, in, inlen);
+                            bufchain_init(&tmp_user_input);
+                            bufchain_add(&tmp_user_input, in, inlen);
+                            ret = get_userpass_input(s->cur_prompt,
+                                                     &tmp_user_input);
+                            bufchain_clear(&tmp_user_input);
 			    ssh->send_ok = 0;
 			}
 			if (!ret) {
@@ -11203,11 +11229,15 @@ static void do_ssh2_authconn(Ssh ssh, const unsigned char *in, int inlen,
 						    ssh->savedhost),
 			   FALSE);
 
-		ret = get_userpass_input(s->cur_prompt, NULL, 0);
+		ret = get_userpass_input(s->cur_prompt, NULL);
 		while (ret < 0) {
+                    bufchain tmp_user_input;
 		    ssh->send_ok = 1;
 		    crWaitUntilV(!pktin);
-		    ret = get_userpass_input(s->cur_prompt, in, inlen);
+                    bufchain_init(&tmp_user_input);
+                    bufchain_add(&tmp_user_input, in, inlen);
+                    ret = get_userpass_input(s->cur_prompt, &tmp_user_input);
+                    bufchain_clear(&tmp_user_input);
 		    ssh->send_ok = 0;
 		}
 		if (!ret) {
@@ -11313,11 +11343,16 @@ static void do_ssh2_authconn(Ssh ssh, const unsigned char *in, int inlen,
 		     */
 		    while (!got_new) {
 
-			ret = get_userpass_input(s->cur_prompt, NULL, 0);
+			ret = get_userpass_input(s->cur_prompt, NULL);
 			while (ret < 0) {
+                            bufchain tmp_user_input;
 			    ssh->send_ok = 1;
 			    crWaitUntilV(!pktin);
-			    ret = get_userpass_input(s->cur_prompt, in, inlen);
+                            bufchain_init(&tmp_user_input);
+                            bufchain_add(&tmp_user_input, in, inlen);
+                            ret = get_userpass_input(s->cur_prompt,
+                                                     &tmp_user_input);
+                            bufchain_clear(&tmp_user_input);
 			    ssh->send_ok = 0;
 			}
 			if (!ret) {
diff --git a/terminal.c b/terminal.c
index 20ab1769..667a29b3 100644
--- a/terminal.c
+++ b/terminal.c
@@ -6718,8 +6718,7 @@ struct term_userpass_state {
  * Process some terminal data in the course of username/password
  * input.
  */
-int term_get_userpass_input(Terminal *term, prompts_t *p,
-			    const unsigned char *in, int inlen)
+int term_get_userpass_input(Terminal *term, prompts_t *p, bufchain *input)
 {
     struct term_userpass_state *s = (struct term_userpass_state *)p->data;
     if (!s) {
@@ -6766,12 +6765,12 @@ int term_get_userpass_input(Terminal *term, prompts_t *p,
 
 	/* Breaking out here ensures that the prompt is printed even
 	 * if we're now waiting for user data. */
-	if (!in || !inlen) break;
+	if (!input || !bufchain_size(input)) break;
 
 	/* FIXME: should we be using local-line-editing code instead? */
-	while (!finished_prompt && inlen) {
-	    char c = *in++;
-	    inlen--;
+	while (!finished_prompt && bufchain_size(input) > 0) {
+	    char c;
+            bufchain_fetch_consume(input, &c, 1);
 	    switch (c) {
 	      case 10:
 	      case 13:
diff --git a/unix/gtkwin.c b/unix/gtkwin.c
index 8dc3b2d4..0771b0b5 100644
--- a/unix/gtkwin.c
+++ b/unix/gtkwin.c
@@ -321,13 +321,13 @@ int from_backend_eof(void *frontend)
     return TRUE;   /* do respond to incoming EOF with outgoing */
 }
 
-int get_userpass_input(prompts_t *p, const unsigned char *in, int inlen)
+int get_userpass_input(prompts_t *p, bufchain *input)
 {
     struct gui_data *inst = (struct gui_data *)p->frontend;
     int ret;
     ret = cmdline_get_passwd_input(p);
     if (ret == -1)
-	ret = term_get_userpass_input(inst->term, p, in, inlen);
+	ret = term_get_userpass_input(inst->term, p, input);
     return ret;
 }
 
diff --git a/unix/uxplink.c b/unix/uxplink.c
index 9ff6f530..c042f459 100644
--- a/unix/uxplink.c
+++ b/unix/uxplink.c
@@ -432,7 +432,7 @@ int from_backend_eof(void *frontend_handle)
     return FALSE;   /* do not respond to incoming EOF with outgoing */
 }
 
-int get_userpass_input(prompts_t *p, const unsigned char *in, int inlen)
+int get_userpass_input(prompts_t *p, bufchain *input)
 {
     int ret;
     ret = cmdline_get_passwd_input(p);
diff --git a/unix/uxsftp.c b/unix/uxsftp.c
index 861baabe..718a29c9 100644
--- a/unix/uxsftp.c
+++ b/unix/uxsftp.c
@@ -68,7 +68,7 @@ Filename *platform_default_filename(const char *name)
 
 char *get_ttymode(void *frontend, const char *mode) { return NULL; }
 
-int get_userpass_input(prompts_t *p, const unsigned char *in, int inlen)
+int get_userpass_input(prompts_t *p, bufchain *input)
 {
     int ret;
     ret = cmdline_get_passwd_input(p);
diff --git a/windows/window.c b/windows/window.c
index 608eb220..5340f7d4 100644
--- a/windows/window.c
+++ b/windows/window.c
@@ -5934,12 +5934,12 @@ int from_backend_eof(void *frontend)
     return TRUE;   /* do respond to incoming EOF with outgoing */
 }
 
-int get_userpass_input(prompts_t *p, const unsigned char *in, int inlen)
+int get_userpass_input(prompts_t *p, bufchain *input)
 {
     int ret;
     ret = cmdline_get_passwd_input(p);
     if (ret == -1)
-	ret = term_get_userpass_input(term, p, in, inlen);
+	ret = term_get_userpass_input(term, p, input);
     return ret;
 }
 
diff --git a/windows/winplink.c b/windows/winplink.c
index 1e5f9f65..5b026b52 100644
--- a/windows/winplink.c
+++ b/windows/winplink.c
@@ -131,12 +131,12 @@ int from_backend_eof(void *frontend_handle)
     return FALSE;   /* do not respond to incoming EOF with outgoing */
 }
 
-int get_userpass_input(prompts_t *p, const unsigned char *in, int inlen)
+int get_userpass_input(prompts_t *p, bufchain *input)
 {
     int ret;
     ret = cmdline_get_passwd_input(p);
     if (ret == -1)
-	ret = console_get_userpass_input(p, in, inlen);
+	ret = console_get_userpass_input(p);
     return ret;
 }
 
diff --git a/windows/winsftp.c b/windows/winsftp.c
index 17d332b7..e9d5d4cb 100644
--- a/windows/winsftp.c
+++ b/windows/winsftp.c
@@ -15,12 +15,12 @@
 
 char *get_ttymode(void *frontend, const char *mode) { return NULL; }
 
-int get_userpass_input(prompts_t *p, const unsigned char *in, int inlen)
+int get_userpass_input(prompts_t *p, bufchain *input)
 {
     int ret;
     ret = cmdline_get_passwd_input(p);
     if (ret == -1)
-	ret = console_get_userpass_input(p, in, inlen);
+	ret = console_get_userpass_input(p);
     return ret;
 }