From 317096dd9789a2a5b101d4f3861c137a75d6258e Mon Sep 17 00:00:00 2001
From: Stefan Eissing <stefan@eissing.org>
Date: Sat, 2 Aug 2025 15:38:12 +0200
Subject: [PATCH] pollset/getsock, increase limit to 16

Let a pollset keep up to 16 sockets, now that IP happy eyeballing
can have several connect attempts open. Make the return bits from
`getsock()` calls unsigned.

This is a stopgap, as even 16 might not be enough when there is
HTTPS eyeballing in top of IP eyeballing with many A+AAAA entries
that do not respond right away.
---
 lib/asyn-ares.c    |  2 +-
 lib/asyn-base.c    | 11 ++++++-----
 lib/asyn-thrdd.c   |  4 ++--
 lib/asyn.h         |  8 ++++----
 lib/cfilters.c     | 12 ++++++------
 lib/cfilters.h     |  4 ++--
 lib/ftp.c          | 21 ++++++++++++---------
 lib/hostip.c       |  4 ++--
 lib/hostip.h       |  4 ++--
 lib/http.c         |  6 +++---
 lib/http.h         |  5 +++--
 lib/imap.c         | 11 ++++++-----
 lib/mqtt.c         | 11 ++++++-----
 lib/multi.c        | 15 ++++++++++-----
 lib/multihandle.h  |  6 ------
 lib/multiif.h      | 14 --------------
 lib/pingpong.c     |  5 +++--
 lib/pingpong.h     |  5 +++--
 lib/pop3.c         | 10 ++++++----
 lib/rtsp.c         | 10 ++++++----
 lib/smb.c          | 10 ++++++----
 lib/smtp.c         | 10 ++++++----
 lib/tftp.c         | 10 ++++++----
 lib/transfer.h     |  5 +++--
 lib/urldata.h      | 39 +++++++++++++++++++++++++++++++--------
 lib/vssh/libssh.c  | 11 ++++++-----
 lib/vssh/libssh2.c | 11 ++++++-----
 lib/vssh/wolfssh.c | 12 ++++++------
 28 files changed, 153 insertions(+), 123 deletions(-)

diff --git a/lib/asyn-ares.c b/lib/asyn-ares.c
index 007f1d7123..451964ec1c 100644
--- a/lib/asyn-ares.c
+++ b/lib/asyn-ares.c
@@ -277,7 +277,7 @@ static void async_ares_cleanup(struct Curl_easy *data)
  * (using curl_multi_fdset()) wants to get our fd_set setup.
  */
 
-int Curl_async_getsock(struct Curl_easy *data, curl_socket_t *socks)
+unsigned int Curl_async_getsock(struct Curl_easy *data, curl_socket_t *socks)
 {
   struct async_ares_ctx *ares = &data->state.async.ares;
   DEBUGASSERT(ares->channel);
diff --git a/lib/asyn-base.c b/lib/asyn-base.c
index ea89fba15c..bd4cf99a7d 100644
--- a/lib/asyn-base.c
+++ b/lib/asyn-base.c
@@ -78,14 +78,15 @@
  * Returns: sockets-in-use-bitmap
  */
 
-int Curl_ares_getsock(struct Curl_easy *data,
-                      ares_channel channel,
-                      curl_socket_t *socks)
+unsigned int Curl_ares_getsock(struct Curl_easy *data,
+                               ares_channel channel,
+                               curl_socket_t *socks)
 {
   struct timeval maxtime = { CURL_TIMEOUT_RESOLVE, 0 };
   struct timeval timebuf;
-  int max = ares_getsock(channel,
-                         (ares_socket_t *)socks, MAX_SOCKSPEREASYHANDLE);
+  unsigned int max = ares_getsock(channel,
+                                  (ares_socket_t *)socks,
+                                  MAX_SOCKSPEREASYHANDLE);
   struct timeval *timeout = ares_timeout(channel, &maxtime, &timebuf);
   timediff_t milli = curlx_tvtoms(timeout);
   Curl_expire(data, milli, EXPIRE_ASYNC_NAME);
diff --git a/lib/asyn-thrdd.c b/lib/asyn-thrdd.c
index 19d1336854..448487db8f 100644
--- a/lib/asyn-thrdd.c
+++ b/lib/asyn-thrdd.c
@@ -629,10 +629,10 @@ CURLcode Curl_async_is_resolved(struct Curl_easy *data,
   }
 }
 
-int Curl_async_getsock(struct Curl_easy *data, curl_socket_t *socks)
+unsigned int Curl_async_getsock(struct Curl_easy *data, curl_socket_t *socks)
 {
   struct async_thrdd_ctx *thrdd = &data->state.async.thrdd;
-  int ret_val = 0;
+  unsigned int ret_val = 0;
 #if !defined(CURL_DISABLE_SOCKETPAIR) || defined(USE_HTTPSRR_ARES)
   int socketi = 0;
 #else
diff --git a/lib/asyn.h b/lib/asyn.h
index a336c1e254..ae9b670ecf 100644
--- a/lib/asyn.h
+++ b/lib/asyn.h
@@ -78,7 +78,7 @@ CURLcode Curl_async_get_impl(struct Curl_easy *easy, void **impl);
  * return bitmask indicating what file descriptors (referring to array indexes
  * in the 'sock' array) to wait for, read/write.
  */
-int Curl_async_getsock(struct Curl_easy *data, curl_socket_t *sock);
+unsigned int Curl_async_getsock(struct Curl_easy *data, curl_socket_t *sock);
 
 /*
  * Curl_async_is_resolved()
@@ -127,9 +127,9 @@ struct Curl_addrinfo *Curl_async_getaddrinfo(struct Curl_easy *data,
 /* common functions for c-ares and threaded resolver with HTTPSRR */
 #include <ares.h>
 
-int Curl_ares_getsock(struct Curl_easy *data,
-                      ares_channel channel,
-                      curl_socket_t *socks);
+unsigned int Curl_ares_getsock(struct Curl_easy *data,
+                               ares_channel channel,
+                               curl_socket_t *socks);
 int Curl_ares_perform(ares_channel channel,
                       timediff_t timeout_ms);
 #endif
diff --git a/lib/cfilters.c b/lib/cfilters.c
index c7333e12b0..424fc98c30 100644
--- a/lib/cfilters.c
+++ b/lib/cfilters.c
@@ -1175,10 +1175,10 @@ void Curl_pollset_set(struct Curl_easy *data,
 }
 
 static void ps_add(struct Curl_easy *data, struct easy_pollset *ps,
-                   int bitmap, curl_socket_t *socks)
+                   unsigned int bitmap, curl_socket_t *socks)
 {
   if(bitmap) {
-    int i;
+    unsigned int i;
     for(i = 0; i < MAX_SOCKSPEREASYHANDLE; ++i) {
       if(!(bitmap & GETSOCK_MASK_RW(i)) || !VALID_SOCK((socks[i]))) {
         break;
@@ -1198,13 +1198,13 @@ static void ps_add(struct Curl_easy *data, struct easy_pollset *ps,
 
 void Curl_pollset_add_socks(struct Curl_easy *data,
                             struct easy_pollset *ps,
-                            int (*get_socks_cb)(struct Curl_easy *data,
-                                                curl_socket_t *socks))
+                            unsigned int (*socks_cb)(struct Curl_easy *data,
+                                                     curl_socket_t *socks))
 {
   curl_socket_t socks[MAX_SOCKSPEREASYHANDLE];
-  int bitmap;
+  unsigned int bitmap;
 
-  bitmap = get_socks_cb(data, socks);
+  bitmap = socks_cb(data, socks);
   ps_add(data, ps, bitmap, socks);
 }
 
diff --git a/lib/cfilters.h b/lib/cfilters.h
index 0b6e1044fc..509063e1d8 100644
--- a/lib/cfilters.h
+++ b/lib/cfilters.h
@@ -664,8 +664,8 @@ void Curl_pollset_set(struct Curl_easy *data,
 
 void Curl_pollset_add_socks(struct Curl_easy *data,
                             struct easy_pollset *ps,
-                            int (*get_socks_cb)(struct Curl_easy *data,
-                                                curl_socket_t *socks));
+                            unsigned int (*socks_cb)(struct Curl_easy *data,
+                                                     curl_socket_t *socks));
 
 /**
  * Check if the pollset, as is, wants to read and/or write regarding
diff --git a/lib/ftp.c b/lib/ftp.c
index 18613ae80e..c71e39f0bc 100644
--- a/lib/ftp.c
+++ b/lib/ftp.c
@@ -214,10 +214,12 @@ static CURLcode ftp_disconnect(struct Curl_easy *data,
                                struct connectdata *conn, bool dead_connection);
 static CURLcode ftp_do_more(struct Curl_easy *data, int *completed);
 static CURLcode ftp_multi_statemach(struct Curl_easy *data, bool *done);
-static int ftp_getsock(struct Curl_easy *data, struct connectdata *conn,
-                       curl_socket_t *socks);
-static int ftp_domore_getsock(struct Curl_easy *data,
-                              struct connectdata *conn, curl_socket_t *socks);
+static unsigned int ftp_getsock(struct Curl_easy *data,
+                                struct connectdata *conn,
+                                curl_socket_t *socks);
+static unsigned int ftp_domore_getsock(struct Curl_easy *data,
+                                       struct connectdata *conn,
+                                       curl_socket_t *socks);
 static CURLcode ftp_doing(struct Curl_easy *data,
                           bool *dophase_done);
 static CURLcode ftp_setup_connection(struct Curl_easy *data,
@@ -781,17 +783,18 @@ static CURLcode ftp_state_pwd(struct Curl_easy *data,
 }
 
 /* For the FTP "protocol connect" and "doing" phases only */
-static int ftp_getsock(struct Curl_easy *data,
-                       struct connectdata *conn,
-                       curl_socket_t *socks)
+static unsigned int ftp_getsock(struct Curl_easy *data,
+                                struct connectdata *conn,
+                                curl_socket_t *socks)
 {
   struct ftp_conn *ftpc = Curl_conn_meta_get(conn, CURL_META_FTP_CONN);
   return ftpc ? Curl_pp_getsock(data, &ftpc->pp, socks) : GETSOCK_BLANK;
 }
 
 /* For the FTP "DO_MORE" phase only */
-static int ftp_domore_getsock(struct Curl_easy *data,
-                              struct connectdata *conn, curl_socket_t *socks)
+static unsigned int ftp_domore_getsock(struct Curl_easy *data,
+                                       struct connectdata *conn,
+                                       curl_socket_t *socks)
 {
   struct ftp_conn *ftpc = Curl_conn_meta_get(conn, CURL_META_FTP_CONN);
   (void)data;
diff --git a/lib/hostip.c b/lib/hostip.c
index 95c2c62242..ae63ab3293 100644
--- a/lib/hostip.c
+++ b/lib/hostip.c
@@ -1523,8 +1523,8 @@ CURLcode Curl_resolv_check(struct Curl_easy *data,
 }
 #endif
 
-int Curl_resolv_getsock(struct Curl_easy *data,
-                        curl_socket_t *socks)
+unsigned int Curl_resolv_getsock(struct Curl_easy *data,
+                                 curl_socket_t *socks)
 {
 #ifdef CURLRES_ASYNCH
 #ifndef CURL_DISABLE_DOH
diff --git a/lib/hostip.h b/lib/hostip.h
index 56c5e9cad1..978cd83909 100644
--- a/lib/hostip.h
+++ b/lib/hostip.h
@@ -199,8 +199,8 @@ CURLcode Curl_resolv_check(struct Curl_easy *data,
 #else
 #define Curl_resolv_check(x,y) CURLE_NOT_BUILT_IN
 #endif
-int Curl_resolv_getsock(struct Curl_easy *data,
-                        curl_socket_t *socks);
+unsigned int Curl_resolv_getsock(struct Curl_easy *data,
+                                 curl_socket_t *socks);
 
 CURLcode Curl_resolver_error(struct Curl_easy *data);
 
diff --git a/lib/http.c b/lib/http.c
index aa48887723..2fb59356a0 100644
--- a/lib/http.c
+++ b/lib/http.c
@@ -1524,9 +1524,9 @@ CURLcode Curl_http_connect(struct Curl_easy *data, bool *done)
 /* this returns the socket to wait for in the DO and DOING state for the multi
    interface and then we are always _sending_ a request and thus we wait for
    the single socket to become writable only */
-int Curl_http_getsock_do(struct Curl_easy *data,
-                         struct connectdata *conn,
-                         curl_socket_t *socks)
+unsigned int Curl_http_getsock_do(struct Curl_easy *data,
+                                  struct connectdata *conn,
+                                  curl_socket_t *socks)
 {
   /* write mode */
   (void)conn;
diff --git a/lib/http.h b/lib/http.h
index a7bc2c6537..01068bf6ed 100644
--- a/lib/http.h
+++ b/lib/http.h
@@ -115,8 +115,9 @@ CURLcode Curl_http_setup_conn(struct Curl_easy *data,
 CURLcode Curl_http(struct Curl_easy *data, bool *done);
 CURLcode Curl_http_done(struct Curl_easy *data, CURLcode, bool premature);
 CURLcode Curl_http_connect(struct Curl_easy *data, bool *done);
-int Curl_http_getsock_do(struct Curl_easy *data, struct connectdata *conn,
-                         curl_socket_t *socks);
+unsigned int Curl_http_getsock_do(struct Curl_easy *data,
+                                  struct connectdata *conn,
+                                  curl_socket_t *socks);
 CURLcode Curl_http_write_resp(struct Curl_easy *data,
                               const char *buf, size_t blen,
                               bool is_eos);
diff --git a/lib/imap.c b/lib/imap.c
index f25176bb9e..2c9d06676d 100644
--- a/lib/imap.c
+++ b/lib/imap.c
@@ -157,8 +157,9 @@ static CURLcode imap_connect(struct Curl_easy *data, bool *done);
 static CURLcode imap_disconnect(struct Curl_easy *data,
                                 struct connectdata *conn, bool dead);
 static CURLcode imap_multi_statemach(struct Curl_easy *data, bool *done);
-static int imap_getsock(struct Curl_easy *data, struct connectdata *conn,
-                        curl_socket_t *socks);
+static unsigned int imap_getsock(struct Curl_easy *data,
+                                 struct connectdata *conn,
+                                 curl_socket_t *socks);
 static CURLcode imap_doing(struct Curl_easy *data, bool *dophase_done);
 static CURLcode imap_setup_connection(struct Curl_easy *data,
                                       struct connectdata *conn);
@@ -1560,9 +1561,9 @@ static CURLcode imap_block_statemach(struct Curl_easy *data,
 }
 
 /* For the IMAP "protocol connect" and "doing" phases only */
-static int imap_getsock(struct Curl_easy *data,
-                        struct connectdata *conn,
-                        curl_socket_t *socks)
+static unsigned int imap_getsock(struct Curl_easy *data,
+                                 struct connectdata *conn,
+                                 curl_socket_t *socks)
 {
   struct imap_conn *imapc = Curl_conn_meta_get(conn, CURL_META_IMAP_CONN);
   return imapc ?
diff --git a/lib/mqtt.c b/lib/mqtt.c
index 90f857dca5..0b737135e1 100644
--- a/lib/mqtt.c
+++ b/lib/mqtt.c
@@ -107,8 +107,9 @@ static CURLcode mqtt_do(struct Curl_easy *data, bool *done);
 static CURLcode mqtt_done(struct Curl_easy *data,
                           CURLcode status, bool premature);
 static CURLcode mqtt_doing(struct Curl_easy *data, bool *done);
-static int mqtt_getsock(struct Curl_easy *data, struct connectdata *conn,
-                        curl_socket_t *sock);
+static unsigned int mqtt_getsock(struct Curl_easy *data,
+                                 struct connectdata *conn,
+                                 curl_socket_t *sock);
 static CURLcode mqtt_setup_conn(struct Curl_easy *data,
                                 struct connectdata *conn);
 
@@ -213,9 +214,9 @@ static CURLcode mqtt_send(struct Curl_easy *data,
 /* Generic function called by the multi interface to figure out what socket(s)
    to wait for and for what actions during the DOING and PROTOCONNECT
    states */
-static int mqtt_getsock(struct Curl_easy *data,
-                        struct connectdata *conn,
-                        curl_socket_t *sock)
+static unsigned int mqtt_getsock(struct Curl_easy *data,
+                                 struct connectdata *conn,
+                                 curl_socket_t *sock)
 {
   (void)data;
   sock[0] = conn->sock[FIRSTSOCKET];
diff --git a/lib/multi.c b/lib/multi.c
index 194cf75d40..8fb9410124 100644
--- a/lib/multi.c
+++ b/lib/multi.c
@@ -907,7 +907,8 @@ void Curl_attach_connection(struct Curl_easy *data,
     conn->handler->attach(data, conn);
 }
 
-static int connecting_getsock(struct Curl_easy *data, curl_socket_t *socks)
+static unsigned int connecting_getsock(struct Curl_easy *data,
+                                       curl_socket_t *socks)
 {
   struct connectdata *conn = data->conn;
   curl_socket_t sockfd;
@@ -923,7 +924,8 @@ static int connecting_getsock(struct Curl_easy *data, curl_socket_t *socks)
   return GETSOCK_BLANK;
 }
 
-static int protocol_getsock(struct Curl_easy *data, curl_socket_t *socks)
+static unsigned int protocol_getsock(struct Curl_easy *data,
+                                     curl_socket_t *socks)
 {
   struct connectdata *conn = data->conn;
   curl_socket_t sockfd;
@@ -941,7 +943,8 @@ static int protocol_getsock(struct Curl_easy *data, curl_socket_t *socks)
   return GETSOCK_BLANK;
 }
 
-static int domore_getsock(struct Curl_easy *data, curl_socket_t *socks)
+static unsigned int domore_getsock(struct Curl_easy *data,
+                                   curl_socket_t *socks)
 {
   struct connectdata *conn = data->conn;
   if(!conn)
@@ -956,7 +959,8 @@ static int domore_getsock(struct Curl_easy *data, curl_socket_t *socks)
   return GETSOCK_BLANK;
 }
 
-static int doing_getsock(struct Curl_easy *data, curl_socket_t *socks)
+static unsigned int doing_getsock(struct Curl_easy *data,
+                                  curl_socket_t *socks)
 {
   struct connectdata *conn = data->conn;
   if(!conn)
@@ -971,7 +975,8 @@ static int doing_getsock(struct Curl_easy *data, curl_socket_t *socks)
   return GETSOCK_BLANK;
 }
 
-static int perform_getsock(struct Curl_easy *data, curl_socket_t *sock)
+static unsigned int perform_getsock(struct Curl_easy *data,
+                                    curl_socket_t *sock)
 {
   struct connectdata *conn = data->conn;
   if(!conn)
diff --git a/lib/multihandle.h b/lib/multihandle.h
index dbad164bc5..cdedfb08ab 100644
--- a/lib/multihandle.h
+++ b/lib/multihandle.h
@@ -72,12 +72,6 @@ typedef enum {
   MSTATE_LAST          /* 18 - not a true state, never use this */
 } CURLMstate;
 
-/* we support N sockets per easy handle. Set the corresponding bit to what
-   action we should wait for */
-#define MAX_SOCKSPEREASYHANDLE 5
-#define GETSOCK_READABLE (0x00ff)
-#define GETSOCK_WRITABLE (0xff00)
-
 #define CURLPIPE_ANY (CURLPIPE_MULTIPLEX)
 
 #ifndef CURL_DISABLE_SOCKETPAIR
diff --git a/lib/multiif.h b/lib/multiif.h
index 1ba0d0f838..221de04721 100644
--- a/lib/multiif.h
+++ b/lib/multiif.h
@@ -53,20 +53,6 @@ struct Curl_multi *Curl_multi_handle(unsigned int xfer_table_size,
                                      size_t dnssize,
                                      size_t sesssize);
 
-/* the write bits start at bit 16 for the *getsock() bitmap */
-#define GETSOCK_WRITEBITSTART 16
-
-#define GETSOCK_BLANK 0 /* no bits set */
-
-/* set the bit for the given sock number to make the bitmap for writable */
-#define GETSOCK_WRITESOCK(x) (1 << (GETSOCK_WRITEBITSTART + (x)))
-
-/* set the bit for the given sock number to make the bitmap for readable */
-#define GETSOCK_READSOCK(x) (1 << (x))
-
-/* mask for checking if read and/or write is set for index x */
-#define GETSOCK_MASK_RW(x) (GETSOCK_READSOCK(x)|GETSOCK_WRITESOCK(x))
-
 /**
  * Let the multi handle know that the socket is about to be closed.
  * The multi will then remove anything it knows about the socket, so
diff --git a/lib/pingpong.c b/lib/pingpong.c
index a661a0285b..c86cd7f619 100644
--- a/lib/pingpong.c
+++ b/lib/pingpong.c
@@ -397,8 +397,9 @@ CURLcode Curl_pp_readresp(struct Curl_easy *data,
   return result;
 }
 
-int Curl_pp_getsock(struct Curl_easy *data,
-                    struct pingpong *pp, curl_socket_t *socks)
+unsigned int Curl_pp_getsock(struct Curl_easy *data,
+                             struct pingpong *pp,
+                             curl_socket_t *socks)
 {
   struct connectdata *conn = data->conn;
   socks[0] = conn->sock[FIRSTSOCKET];
diff --git a/lib/pingpong.h b/lib/pingpong.h
index c6d0a56f0d..7cf60c4781 100644
--- a/lib/pingpong.h
+++ b/lib/pingpong.h
@@ -147,8 +147,9 @@ CURLcode Curl_pp_flushsend(struct Curl_easy *data,
 /* call this when a pingpong connection is disconnected */
 CURLcode Curl_pp_disconnect(struct pingpong *pp);
 
-int Curl_pp_getsock(struct Curl_easy *data, struct pingpong *pp,
-                    curl_socket_t *socks);
+unsigned int Curl_pp_getsock(struct Curl_easy *data,
+                             struct pingpong *pp,
+                             curl_socket_t *socks);
 
 
 /***********************************************************************
diff --git a/lib/pop3.c b/lib/pop3.c
index 514c4b8fa5..c37cf15e2d 100644
--- a/lib/pop3.c
+++ b/lib/pop3.c
@@ -153,8 +153,9 @@ static CURLcode pop3_connect(struct Curl_easy *data, bool *done);
 static CURLcode pop3_disconnect(struct Curl_easy *data,
                                 struct connectdata *conn, bool dead);
 static CURLcode pop3_multi_statemach(struct Curl_easy *data, bool *done);
-static int pop3_getsock(struct Curl_easy *data,
-                        struct connectdata *conn, curl_socket_t *socks);
+static unsigned int pop3_getsock(struct Curl_easy *data,
+                                 struct connectdata *conn,
+                                 curl_socket_t *socks);
 static CURLcode pop3_doing(struct Curl_easy *data, bool *dophase_done);
 static CURLcode pop3_setup_connection(struct Curl_easy *data,
                                       struct connectdata *conn);
@@ -1269,8 +1270,9 @@ static CURLcode pop3_block_statemach(struct Curl_easy *data,
 }
 
 /* For the POP3 "protocol connect" and "doing" phases only */
-static int pop3_getsock(struct Curl_easy *data,
-                        struct connectdata *conn, curl_socket_t *socks)
+static unsigned int pop3_getsock(struct Curl_easy *data,
+                                 struct connectdata *conn,
+                                 curl_socket_t *socks)
 {
   struct pop3_conn *pop3c = Curl_conn_meta_get(conn, CURL_META_POP3_CONN);
   if(pop3c)
diff --git a/lib/rtsp.c b/lib/rtsp.c
index d50624158e..91ccc4ed0b 100644
--- a/lib/rtsp.c
+++ b/lib/rtsp.c
@@ -83,8 +83,9 @@ struct RTSP {
 static CURLcode rtsp_do(struct Curl_easy *data, bool *done);
 static CURLcode rtsp_done(struct Curl_easy *data, CURLcode, bool premature);
 static CURLcode rtsp_connect(struct Curl_easy *data, bool *done);
-static int rtsp_getsock_do(struct Curl_easy *data,
-                           struct connectdata *conn, curl_socket_t *socks);
+static unsigned int rtsp_getsock_do(struct Curl_easy *data,
+                                    struct connectdata *conn,
+                                    curl_socket_t *socks);
 
 /*
  * Parse and write out an RTSP response.
@@ -110,8 +111,9 @@ static unsigned int rtsp_conncheck(struct Curl_easy *data,
 /* this returns the socket to wait for in the DO and DOING state for the multi
    interface and then we are always _sending_ a request and thus we wait for
    the single socket to become writable only */
-static int rtsp_getsock_do(struct Curl_easy *data, struct connectdata *conn,
-                           curl_socket_t *socks)
+static unsigned int rtsp_getsock_do(struct Curl_easy *data,
+                                    struct connectdata *conn,
+                                    curl_socket_t *socks)
 {
   /* write mode */
   (void)data;
diff --git a/lib/smb.c b/lib/smb.c
index d6ef8f6f1d..f5235102b9 100644
--- a/lib/smb.c
+++ b/lib/smb.c
@@ -298,8 +298,9 @@ static CURLcode smb_connect(struct Curl_easy *data, bool *done);
 static CURLcode smb_connection_state(struct Curl_easy *data, bool *done);
 static CURLcode smb_do(struct Curl_easy *data, bool *done);
 static CURLcode smb_request_state(struct Curl_easy *data, bool *done);
-static int smb_getsock(struct Curl_easy *data, struct connectdata *conn,
-                       curl_socket_t *socks);
+static unsigned int smb_getsock(struct Curl_easy *data,
+                                struct connectdata *conn,
+                                curl_socket_t *socks);
 static CURLcode smb_parse_url_path(struct Curl_easy *data,
                                    struct smb_conn *smbc,
                                    struct smb_request *req);
@@ -1204,8 +1205,9 @@ static CURLcode smb_request_state(struct Curl_easy *data, bool *done)
   return CURLE_OK;
 }
 
-static int smb_getsock(struct Curl_easy *data,
-                       struct connectdata *conn, curl_socket_t *socks)
+static unsigned int smb_getsock(struct Curl_easy *data,
+                                struct connectdata *conn,
+                                curl_socket_t *socks)
 {
   (void)data;
   socks[0] = conn->sock[FIRSTSOCKET];
diff --git a/lib/smtp.c b/lib/smtp.c
index 13b89b6ecc..4ba5d14171 100644
--- a/lib/smtp.c
+++ b/lib/smtp.c
@@ -157,8 +157,9 @@ static CURLcode smtp_connect(struct Curl_easy *data, bool *done);
 static CURLcode smtp_disconnect(struct Curl_easy *data,
                                 struct connectdata *conn, bool dead);
 static CURLcode smtp_multi_statemach(struct Curl_easy *data, bool *done);
-static int smtp_getsock(struct Curl_easy *data,
-                        struct connectdata *conn, curl_socket_t *socks);
+static unsigned int smtp_getsock(struct Curl_easy *data,
+                                 struct connectdata *conn,
+                                 curl_socket_t *socks);
 static CURLcode smtp_doing(struct Curl_easy *data, bool *dophase_done);
 static CURLcode smtp_setup_connection(struct Curl_easy *data,
                                       struct connectdata *conn);
@@ -1413,8 +1414,9 @@ static CURLcode smtp_block_statemach(struct Curl_easy *data,
 }
 
 /* For the SMTP "protocol connect" and "doing" phases only */
-static int smtp_getsock(struct Curl_easy *data,
-                        struct connectdata *conn, curl_socket_t *socks)
+static unsigned int smtp_getsock(struct Curl_easy *data,
+                                 struct connectdata *conn,
+                                 curl_socket_t *socks)
 {
   struct smtp_conn *smtpc = Curl_conn_meta_get(conn, CURL_META_SMTP_CONN);
   return smtpc ?
diff --git a/lib/tftp.c b/lib/tftp.c
index 5ea986dbb4..6412360ca4 100644
--- a/lib/tftp.c
+++ b/lib/tftp.c
@@ -160,8 +160,9 @@ static CURLcode tftp_setup_connection(struct Curl_easy *data,
                                       struct connectdata *conn);
 static CURLcode tftp_multi_statemach(struct Curl_easy *data, bool *done);
 static CURLcode tftp_doing(struct Curl_easy *data, bool *dophase_done);
-static int tftp_getsock(struct Curl_easy *data, struct connectdata *conn,
-                        curl_socket_t *socks);
+static unsigned int tftp_getsock(struct Curl_easy *data,
+                                 struct connectdata *conn,
+                                 curl_socket_t *socks);
 static CURLcode tftp_translate_code(tftp_error_t error);
 
 
@@ -1081,8 +1082,9 @@ static CURLcode tftp_done(struct Curl_easy *data, CURLcode status,
  * The getsock callback
  *
  **********************************************************/
-static int tftp_getsock(struct Curl_easy *data,
-                        struct connectdata *conn, curl_socket_t *socks)
+static unsigned int tftp_getsock(struct Curl_easy *data,
+                                 struct connectdata *conn,
+                                 curl_socket_t *socks)
 {
   (void)data;
   socks[0] = conn->sock[FIRSTSOCKET];
diff --git a/lib/transfer.h b/lib/transfer.h
index 92278226be..8f1fe96a60 100644
--- a/lib/transfer.h
+++ b/lib/transfer.h
@@ -34,8 +34,9 @@ void Curl_init_CONNECT(struct Curl_easy *data);
 CURLcode Curl_pretransfer(struct Curl_easy *data);
 
 CURLcode Curl_sendrecv(struct Curl_easy *data, struct curltime *nowp);
-int Curl_single_getsock(struct Curl_easy *data,
-                        struct connectdata *conn, curl_socket_t *socks);
+unsigned int Curl_single_getsock(struct Curl_easy *data,
+                                 struct connectdata *conn,
+                                 curl_socket_t *socks);
 CURLcode Curl_retry_request(struct Curl_easy *data, char **url);
 bool Curl_meets_timecondition(struct Curl_easy *data, time_t timeofdoc);
 
diff --git a/lib/urldata.h b/lib/urldata.h
index 2ae52840f5..dcc76d222f 100644
--- a/lib/urldata.h
+++ b/lib/urldata.h
@@ -471,6 +471,25 @@ struct hostname {
 #define FIRSTSOCKET     0
 #define SECONDARYSOCKET 1
 
+/* we support N sockets per easy handle. Set the corresponding bit to what
+   action we should wait for */
+#define MAX_SOCKSPEREASYHANDLE 16
+
+/* the write bits start at bit 16 for the *getsock() bitmap */
+#define GETSOCK_WRITEBITSTART 16
+
+#define GETSOCK_BLANK 0U /* no bits set */
+
+/* set the bit for the given sock number to make the bitmap for writable */
+#define GETSOCK_WRITESOCK(x) (1U << (GETSOCK_WRITEBITSTART + (x)))
+
+/* set the bit for the given sock number to make the bitmap for readable */
+#define GETSOCK_READSOCK(x) (1U << (x))
+
+/* mask for checking if read and/or write is set for index x */
+#define GETSOCK_MASK_RW(x) (GETSOCK_READSOCK(x)|GETSOCK_WRITESOCK(x))
+
+
 /* Polling requested by an easy handle.
  * `action` is CURL_POLL_IN, CURL_POLL_OUT or CURL_POLL_INOUT.
  */
@@ -516,24 +535,28 @@ struct Curl_handler {
 
   /* Called from the multi interface during the PROTOCONNECT phase, and it
      should then return a proper fd set */
-  int (*proto_getsock)(struct Curl_easy *data,
-                       struct connectdata *conn, curl_socket_t *socks);
+  unsigned int (*proto_getsock)(struct Curl_easy *data,
+                                struct connectdata *conn,
+                                curl_socket_t *socks);
 
   /* Called from the multi interface during the DOING phase, and it should
      then return a proper fd set */
-  int (*doing_getsock)(struct Curl_easy *data,
-                       struct connectdata *conn, curl_socket_t *socks);
+  unsigned int (*doing_getsock)(struct Curl_easy *data,
+                                struct connectdata *conn,
+                                curl_socket_t *socks);
 
   /* Called from the multi interface during the DO_MORE phase, and it should
      then return a proper fd set */
-  int (*domore_getsock)(struct Curl_easy *data,
-                        struct connectdata *conn, curl_socket_t *socks);
+  unsigned int (*domore_getsock)(struct Curl_easy *data,
+                                 struct connectdata *conn,
+                                 curl_socket_t *socks);
 
   /* Called from the multi interface during the DO_DONE, PERFORM and
      WAITPERFORM phases, and it should then return a proper fd set. Not setting
      this will make libcurl use the generic default one. */
-  int (*perform_getsock)(struct Curl_easy *data,
-                         struct connectdata *conn, curl_socket_t *socks);
+  unsigned int (*perform_getsock)(struct Curl_easy *data,
+                                  struct connectdata *conn,
+                                  curl_socket_t *socks);
 
   /* This function *MAY* be set to a protocol-dependent function that is run
    * by the curl_disconnect(), as a step in the disconnection. If the handler
diff --git a/lib/vssh/libssh.c b/lib/vssh/libssh.c
index d9c37f9db5..8cc976e0b2 100644
--- a/lib/vssh/libssh.c
+++ b/lib/vssh/libssh.c
@@ -125,8 +125,9 @@ CURLcode sftp_perform(struct Curl_easy *data,
                       bool *connected,
                       bool *dophase_done);
 
-static int myssh_getsock(struct Curl_easy *data,
-                         struct connectdata *conn, curl_socket_t *sock);
+static unsigned int myssh_getsock(struct Curl_easy *data,
+                                  struct connectdata *conn,
+                                  curl_socket_t *sock);
 static void myssh_block2waitfor(struct connectdata *conn,
                                 struct ssh_conn *sshc,
                                 bool block);
@@ -2390,9 +2391,9 @@ static CURLcode myssh_statemach_act(struct Curl_easy *data,
 
 /* called by the multi interface to figure out what socket(s) to wait for and
    for what actions in the DO_DONE, PERFORM and WAITPERFORM states */
-static int myssh_getsock(struct Curl_easy *data,
-                         struct connectdata *conn,
-                         curl_socket_t *sock)
+static unsigned int myssh_getsock(struct Curl_easy *data,
+                                  struct connectdata *conn,
+                                  curl_socket_t *sock)
 {
   int bitmap = GETSOCK_BLANK;
   (void)data;
diff --git a/lib/vssh/libssh2.c b/lib/vssh/libssh2.c
index ab57dd87f5..07a87b5c79 100644
--- a/lib/vssh/libssh2.c
+++ b/lib/vssh/libssh2.c
@@ -99,8 +99,9 @@ static CURLcode sftp_disconnect(struct Curl_easy *data,
                                 struct connectdata *conn, bool dead);
 static CURLcode sftp_perform(struct Curl_easy *data, bool *connected,
                              bool *dophase_done);
-static int ssh_getsock(struct Curl_easy *data, struct connectdata *conn,
-                       curl_socket_t *sock);
+static unsigned int ssh_getsock(struct Curl_easy *data,
+                                struct connectdata *conn,
+                                curl_socket_t *sock);
 static CURLcode ssh_setup_connection(struct Curl_easy *data,
                                      struct connectdata *conn);
 static void ssh_attach(struct Curl_easy *data, struct connectdata *conn);
@@ -3087,9 +3088,9 @@ static CURLcode ssh_statemachine(struct Curl_easy *data,
 
 /* called by the multi interface to figure out what socket(s) to wait for and
    for what actions in the DO_DONE, PERFORM and WAITPERFORM states */
-static int ssh_getsock(struct Curl_easy *data,
-                       struct connectdata *conn,
-                       curl_socket_t *sock)
+static unsigned int ssh_getsock(struct Curl_easy *data,
+                                struct connectdata *conn,
+                                curl_socket_t *sock)
 {
   int bitmap = GETSOCK_BLANK;
   (void)data;
diff --git a/lib/vssh/wolfssh.c b/lib/vssh/wolfssh.c
index eed73fd919..0555a1af70 100644
--- a/lib/vssh/wolfssh.c
+++ b/lib/vssh/wolfssh.c
@@ -66,9 +66,9 @@ static CURLcode wsftp_doing(struct Curl_easy *data,
 static CURLcode wsftp_disconnect(struct Curl_easy *data,
                                  struct connectdata *conn,
                                  bool dead);
-static int wssh_getsock(struct Curl_easy *data,
-                        struct connectdata *conn,
-                        curl_socket_t *sock);
+static unsigned int wssh_getsock(struct Curl_easy *data,
+                                 struct connectdata *conn,
+                                 curl_socket_t *sock);
 static CURLcode wssh_setup_connection(struct Curl_easy *data,
                                       struct connectdata *conn);
 static void wssh_sshc_cleanup(struct ssh_conn *sshc);
@@ -1185,9 +1185,9 @@ static CURLcode wsftp_disconnect(struct Curl_easy *data,
   return result;
 }
 
-static int wssh_getsock(struct Curl_easy *data,
-                        struct connectdata *conn,
-                        curl_socket_t *sock)
+static unsigned int wssh_getsock(struct Curl_easy *data,
+                                 struct connectdata *conn,
+                                 curl_socket_t *sock)
 {
   int bitmap = GETSOCK_BLANK;
   int dir = conn->waitfor;