handler: refactor connection checking

Add a new type of callback to Curl_handler which performs checks on
the connection. Alter RTSP so that it uses this callback to do its
own check on connection health.

20 files changed, 78 insertions, 7 deletions

diff --git a/lib/curl_rtmp.c b/lib/curl_rtmp.c
index 87a6caf9e..2d7ce5ed2 100644
--- a/lib/curl_rtmp.c
+++ b/lib/curl_rtmp.c
@@ -74,6 +74,7 @@ const struct Curl_handler Curl_handler_rtmp = {
   ZERO_NULL,                            /* perform_getsock */
   rtmp_disconnect,                      /* disconnect */
   ZERO_NULL,                            /* readwrite */
+  ZERO_NULL,                            /* connection_check */
   PORT_RTMP,                            /* defport */
   CURLPROTO_RTMP,                       /* protocol */
   PROTOPT_NONE                          /* flags*/
@@ -94,6 +95,7 @@ const struct Curl_handler Curl_handler_rtmpt = {
   ZERO_NULL,                            /* perform_getsock */
   rtmp_disconnect,                      /* disconnect */
   ZERO_NULL,                            /* readwrite */
+  ZERO_NULL,                            /* connection_check */
   PORT_RTMPT,                           /* defport */
   CURLPROTO_RTMPT,                      /* protocol */
   PROTOPT_NONE                          /* flags*/
@@ -114,6 +116,7 @@ const struct Curl_handler Curl_handler_rtmpe = {
   ZERO_NULL,                            /* perform_getsock */
   rtmp_disconnect,                      /* disconnect */
   ZERO_NULL,                            /* readwrite */
+  ZERO_NULL,                            /* connection_check */
   PORT_RTMP,                            /* defport */
   CURLPROTO_RTMPE,                      /* protocol */
   PROTOPT_NONE                          /* flags*/
@@ -134,6 +137,7 @@ const struct Curl_handler Curl_handler_rtmpte = {
   ZERO_NULL,                            /* perform_getsock */
   rtmp_disconnect,                      /* disconnect */
   ZERO_NULL,                            /* readwrite */
+  ZERO_NULL,                            /* connection_check */
   PORT_RTMPT,                           /* defport */
   CURLPROTO_RTMPTE,                     /* protocol */
   PROTOPT_NONE                          /* flags*/
@@ -154,6 +158,7 @@ const struct Curl_handler Curl_handler_rtmps = {
   ZERO_NULL,                            /* perform_getsock */
   rtmp_disconnect,                      /* disconnect */
   ZERO_NULL,                            /* readwrite */
+  ZERO_NULL,                            /* connection_check */
   PORT_RTMPS,                           /* defport */
   CURLPROTO_RTMPS,                      /* protocol */
   PROTOPT_NONE                          /* flags*/
@@ -174,6 +179,7 @@ const struct Curl_handler Curl_handler_rtmpts = {
   ZERO_NULL,                            /* perform_getsock */
   rtmp_disconnect,                      /* disconnect */
   ZERO_NULL,                            /* readwrite */
+  ZERO_NULL,                            /* connection_check */
   PORT_RTMPS,                           /* defport */
   CURLPROTO_RTMPTS,                     /* protocol */
   PROTOPT_NONE                          /* flags*/
diff --git a/lib/dict.c b/lib/dict.c
index 451ec389a..81d89fc48 100644
--- a/lib/dict.c
+++ b/lib/dict.c
@@ -85,6 +85,7 @@ const struct Curl_handler Curl_handler_dict = {
   ZERO_NULL,                            /* perform_getsock */
   ZERO_NULL,                            /* disconnect */
   ZERO_NULL,                            /* readwrite */
+  ZERO_NULL,                            /* connection_check */
   PORT_DICT,                            /* defport */
   CURLPROTO_DICT,                       /* protocol */
   PROTOPT_NONE | PROTOPT_NOURLQUERY      /* flags */
diff --git a/lib/file.c b/lib/file.c
index c804d75e1..bd426eac2 100644
--- a/lib/file.c
+++ b/lib/file.c
@@ -108,6 +108,7 @@ const struct Curl_handler Curl_handler_file = {
   ZERO_NULL,                            /* perform_getsock */
   file_disconnect,                      /* disconnect */
   ZERO_NULL,                            /* readwrite */
+  ZERO_NULL,                            /* connection_check */
   0,                                    /* defport */
   CURLPROTO_FILE,                       /* protocol */
   PROTOPT_NONETWORK | PROTOPT_NOURLQUERY /* flags */
diff --git a/lib/ftp.c b/lib/ftp.c
index 1e3aa8d7c..6d1f24a32 100644
--- a/lib/ftp.c
+++ b/lib/ftp.c
@@ -178,6 +178,7 @@ const struct Curl_handler Curl_handler_ftp = {
   ZERO_NULL,                       /* perform_getsock */
   ftp_disconnect,                  /* disconnect */
   ZERO_NULL,                       /* readwrite */
+  ZERO_NULL,                       /* connection_check */
   PORT_FTP,                        /* defport */
   CURLPROTO_FTP,                   /* protocol */
   PROTOPT_DUAL | PROTOPT_CLOSEACTION | PROTOPT_NEEDSPWD |
@@ -205,6 +206,7 @@ const struct Curl_handler Curl_handler_ftps = {
   ZERO_NULL,                       /* perform_getsock */
   ftp_disconnect,                  /* disconnect */
   ZERO_NULL,                       /* readwrite */
+  ZERO_NULL,                       /* connection_check */
   PORT_FTPS,                       /* defport */
   CURLPROTO_FTPS,                  /* protocol */
   PROTOPT_SSL | PROTOPT_DUAL | PROTOPT_CLOSEACTION |
diff --git a/lib/gopher.c b/lib/gopher.c
index e6d274648..836f72550 100644
--- a/lib/gopher.c
+++ b/lib/gopher.c
@@ -65,6 +65,7 @@ const struct Curl_handler Curl_handler_gopher = {
   ZERO_NULL,                            /* perform_getsock */
   ZERO_NULL,                            /* disconnect */
   ZERO_NULL,                            /* readwrite */
+  ZERO_NULL,                            /* connection_check */
   PORT_GOPHER,                          /* defport */
   CURLPROTO_GOPHER,                     /* protocol */
   PROTOPT_NONE                          /* flags */
diff --git a/lib/http.c b/lib/http.c
index b8f4c8a21..e611214fb 100644
--- a/lib/http.c
+++ b/lib/http.c
@@ -119,6 +119,7 @@ const struct Curl_handler Curl_handler_http = {
   ZERO_NULL,                            /* perform_getsock */
   ZERO_NULL,                            /* disconnect */
   ZERO_NULL,                            /* readwrite */
+  ZERO_NULL,                            /* connection_check */
   PORT_HTTP,                            /* defport */
   CURLPROTO_HTTP,                       /* protocol */
   PROTOPT_CREDSPERREQUEST               /* flags */
@@ -143,6 +144,7 @@ const struct Curl_handler Curl_handler_https = {
   ZERO_NULL,                            /* perform_getsock */
   ZERO_NULL,                            /* disconnect */
   ZERO_NULL,                            /* readwrite */
+  ZERO_NULL,                            /* connection_check */
   PORT_HTTPS,                           /* defport */
   CURLPROTO_HTTPS,                      /* protocol */
   PROTOPT_SSL | PROTOPT_CREDSPERREQUEST | PROTOPT_ALPN_NPN /* flags */
diff --git a/lib/http2.c b/lib/http2.c
index 98fc147a9..a93348641 100644
--- a/lib/http2.c
+++ b/lib/http2.c
@@ -196,6 +196,7 @@ static const struct Curl_handler Curl_handler_http2 = {
   http2_perform_getsock,                /* perform_getsock */
   http2_disconnect,                     /* disconnect */
   ZERO_NULL,                            /* readwrite */
+  ZERO_NULL,                            /* connection_check */
   PORT_HTTP,                            /* defport */
   CURLPROTO_HTTP,                       /* protocol */
   PROTOPT_STREAM                        /* flags */
@@ -216,6 +217,7 @@ static const struct Curl_handler Curl_handler_http2_ssl = {
   http2_perform_getsock,                /* perform_getsock */
   http2_disconnect,                     /* disconnect */
   ZERO_NULL,                            /* readwrite */
+  ZERO_NULL,                            /* connection_check */
   PORT_HTTP,                            /* defport */
   CURLPROTO_HTTPS,                      /* protocol */
   PROTOPT_SSL | PROTOPT_STREAM          /* flags */
diff --git a/lib/imap.c b/lib/imap.c
index 18b1760fc..48af2902a 100644
--- a/lib/imap.c
+++ b/lib/imap.c
@@ -128,6 +128,7 @@ const struct Curl_handler Curl_handler_imap = {
   ZERO_NULL,                        /* perform_getsock */
   imap_disconnect,                  /* disconnect */
   ZERO_NULL,                        /* readwrite */
+  ZERO_NULL,                        /* connection_check */
   PORT_IMAP,                        /* defport */
   CURLPROTO_IMAP,                   /* protocol */
   PROTOPT_CLOSEACTION|              /* flags */
@@ -154,6 +155,7 @@ const struct Curl_handler Curl_handler_imaps = {
   ZERO_NULL,                        /* perform_getsock */
   imap_disconnect,                  /* disconnect */
   ZERO_NULL,                        /* readwrite */
+  ZERO_NULL,                        /* connection_check */
   PORT_IMAPS,                       /* defport */
   CURLPROTO_IMAPS,                  /* protocol */
   PROTOPT_CLOSEACTION | PROTOPT_SSL /* flags */
diff --git a/lib/ldap.c b/lib/ldap.c
index 79e84d94e..421393f11 100644
--- a/lib/ldap.c
+++ b/lib/ldap.c
@@ -150,6 +150,7 @@ const struct Curl_handler Curl_handler_ldap = {
   ZERO_NULL,                            /* perform_getsock */
   ZERO_NULL,                            /* disconnect */
   ZERO_NULL,                            /* readwrite */
+  ZERO_NULL,                            /* connection_check */
   PORT_LDAP,                            /* defport */
   CURLPROTO_LDAP,                       /* protocol */
   PROTOPT_NONE                          /* flags */
@@ -175,6 +176,7 @@ const struct Curl_handler Curl_handler_ldaps = {
   ZERO_NULL,                            /* perform_getsock */
   ZERO_NULL,                            /* disconnect */
   ZERO_NULL,                            /* readwrite */
+  ZERO_NULL,                            /* connection_check */
   PORT_LDAPS,                           /* defport */
   CURLPROTO_LDAPS,                      /* protocol */
   PROTOPT_SSL                           /* flags */
diff --git a/lib/openldap.c b/lib/openldap.c
index 4b8cfb9c2..369309cf5 100644
--- a/lib/openldap.c
+++ b/lib/openldap.c
@@ -85,6 +85,7 @@ const struct Curl_handler Curl_handler_ldap = {
   ZERO_NULL,                            /* perform_getsock */
   ldap_disconnect,                      /* disconnect */
   ZERO_NULL,                            /* readwrite */
+  ZERO_NULL,                            /* connection_check */
   PORT_LDAP,                            /* defport */
   CURLPROTO_LDAP,                       /* protocol */
   PROTOPT_NONE                          /* flags */
@@ -110,6 +111,7 @@ const struct Curl_handler Curl_handler_ldaps = {
   ZERO_NULL,                            /* perform_getsock */
   ldap_disconnect,                      /* disconnect */
   ZERO_NULL,                            /* readwrite */
+  ZERO_NULL,                            /* connection_check */
   PORT_LDAPS,                           /* defport */
   CURLPROTO_LDAP,                       /* protocol */
   PROTOPT_SSL                           /* flags */
diff --git a/lib/pop3.c b/lib/pop3.c
index 4aff6031c..5792a4a6f 100644
--- a/lib/pop3.c
+++ b/lib/pop3.c
@@ -125,6 +125,7 @@ const struct Curl_handler Curl_handler_pop3 = {
   ZERO_NULL,                        /* perform_getsock */
   pop3_disconnect,                  /* disconnect */
   ZERO_NULL,                        /* readwrite */
+  ZERO_NULL,                        /* connection_check */
   PORT_POP3,                        /* defport */
   CURLPROTO_POP3,                   /* protocol */
   PROTOPT_CLOSEACTION | PROTOPT_NOURLQUERY | /* flags */
@@ -151,6 +152,7 @@ const struct Curl_handler Curl_handler_pop3s = {
   ZERO_NULL,                        /* perform_getsock */
   pop3_disconnect,                  /* disconnect */
   ZERO_NULL,                        /* readwrite */
+  ZERO_NULL,                        /* connection_check */
   PORT_POP3S,                       /* defport */
   CURLPROTO_POP3S,                  /* protocol */
   PROTOPT_CLOSEACTION | PROTOPT_SSL
diff --git a/lib/rtsp.c b/lib/rtsp.c
index 1810cdafb..9bd935fd5 100644
--- a/lib/rtsp.c
+++ b/lib/rtsp.c
@@ -81,6 +81,9 @@ static CURLcode rtsp_rtp_readwrite(struct Curl_easy *data,
 
 static CURLcode rtsp_setup_connection(struct connectdata *conn);
 
+bool rtsp_connisdead(struct connectdata *check);
+static unsigned int rtsp_conncheck(struct connectdata *check,
+                                   unsigned int checks_to_perform);
 
 /* this returns the socket to wait for in the DO and DOING state for the multi
    interface and then we're always _sending_ a request and thus we wait for
@@ -117,6 +120,7 @@ const struct Curl_handler Curl_handler_rtsp = {
   ZERO_NULL,                            /* perform_getsock */
   rtsp_disconnect,                      /* disconnect */
   rtsp_rtp_readwrite,                   /* readwrite */
+  rtsp_conncheck,                       /* connection_check */
   PORT_RTSP,                            /* defport */
   CURLPROTO_RTSP,                       /* protocol */
   PROTOPT_NONE                          /* flags */
@@ -143,7 +147,7 @@ static CURLcode rtsp_setup_connection(struct connectdata *conn)
  * Instead, if it is readable, run Curl_connalive() to peek at the socket
  * and distinguish between closed and data.
  */
-bool Curl_rtsp_connisdead(struct connectdata *check)
+bool rtsp_connisdead(struct connectdata *check)
 {
   int sval;
   bool ret_val = TRUE;
@@ -165,6 +169,23 @@ bool Curl_rtsp_connisdead(struct connectdata *check)
   return ret_val;
 }
 
+/*
+ * Function to check on various aspects of a connection.
+ */
+static unsigned int rtsp_conncheck(struct connectdata *check,
+                                   unsigned int checks_to_perform)
+{
+  unsigned int ret_val = CONNRESULT_NONE;
+
+  if(checks_to_perform & CONNCHECK_ISDEAD) {
+    if(rtsp_connisdead(check))
+      ret_val |= CONNRESULT_DEAD;
+  }
+
+  return ret_val;
+}
+
+
 static CURLcode rtsp_connect(struct connectdata *conn, bool *done)
 {
   CURLcode httpStatus;
diff --git a/lib/rtsp.h b/lib/rtsp.h
index 5a8d5556f..8375a5317 100644
--- a/lib/rtsp.h
+++ b/lib/rtsp.h
@@ -25,13 +25,11 @@
 
 extern const struct Curl_handler Curl_handler_rtsp;
 
-bool Curl_rtsp_connisdead(struct connectdata *check);
 CURLcode Curl_rtsp_parseheader(struct connectdata *conn, char *header);
 
 #else
 /* disabled */
 #define Curl_rtsp_parseheader(x,y) CURLE_NOT_BUILT_IN
-#define Curl_rtsp_connisdead(x) TRUE
 
 #endif /* CURL_DISABLE_RTSP */
 
diff --git a/lib/smb.c b/lib/smb.c
index 5b1ffa9b7..c2df43b70 100644
--- a/lib/smb.c
+++ b/lib/smb.c
@@ -85,6 +85,7 @@ const struct Curl_handler Curl_handler_smb = {
   ZERO_NULL,                            /* perform_getsock */
   smb_disconnect,                       /* disconnect */
   ZERO_NULL,                            /* readwrite */
+  ZERO_NULL,                            /* connection_check */
   PORT_SMB,                             /* defport */
   CURLPROTO_SMB,                        /* protocol */
   PROTOPT_NONE                          /* flags */
@@ -109,6 +110,7 @@ const struct Curl_handler Curl_handler_smbs = {
   ZERO_NULL,                            /* perform_getsock */
   smb_disconnect,                       /* disconnect */
   ZERO_NULL,                            /* readwrite */
+  ZERO_NULL,                            /* connection_check */
   PORT_SMBS,                            /* defport */
   CURLPROTO_SMBS,                       /* protocol */
   PROTOPT_SSL                           /* flags */
diff --git a/lib/smtp.c b/lib/smtp.c
index e609ec9d9..4e2c3361e 100644
--- a/lib/smtp.c
+++ b/lib/smtp.c
@@ -124,6 +124,7 @@ const struct Curl_handler Curl_handler_smtp = {
   ZERO_NULL,                        /* perform_getsock */
   smtp_disconnect,                  /* disconnect */
   ZERO_NULL,                        /* readwrite */
+  ZERO_NULL,                        /* connection_check */
   PORT_SMTP,                        /* defport */
   CURLPROTO_SMTP,                   /* protocol */
   PROTOPT_CLOSEACTION | PROTOPT_NOURLQUERY | /* flags */
@@ -150,6 +151,7 @@ const struct Curl_handler Curl_handler_smtps = {
   ZERO_NULL,                        /* perform_getsock */
   smtp_disconnect,                  /* disconnect */
   ZERO_NULL,                        /* readwrite */
+  ZERO_NULL,                        /* connection_check */
   PORT_SMTPS,                       /* defport */
   CURLPROTO_SMTPS,                  /* protocol */
   PROTOPT_CLOSEACTION | PROTOPT_SSL
diff --git a/lib/ssh.c b/lib/ssh.c
index 00aeca978..d6620770d 100644
--- a/lib/ssh.c
+++ b/lib/ssh.c
@@ -177,6 +177,7 @@ const struct Curl_handler Curl_handler_scp = {
   ssh_perform_getsock,                  /* perform_getsock */
   scp_disconnect,                       /* disconnect */
   ZERO_NULL,                            /* readwrite */
+  ZERO_NULL,                            /* connection_check */
   PORT_SSH,                             /* defport */
   CURLPROTO_SCP,                        /* protocol */
   PROTOPT_DIRLOCK | PROTOPT_CLOSEACTION
@@ -203,6 +204,7 @@ const struct Curl_handler Curl_handler_sftp = {
   ssh_perform_getsock,                  /* perform_getsock */
   sftp_disconnect,                      /* disconnect */
   ZERO_NULL,                            /* readwrite */
+  ZERO_NULL,                            /* connection_check */
   PORT_SSH,                             /* defport */
   CURLPROTO_SFTP,                       /* protocol */
   PROTOPT_DIRLOCK | PROTOPT_CLOSEACTION
diff --git a/lib/telnet.c b/lib/telnet.c
index 155d4b260..122100523 100644
--- a/lib/telnet.c
+++ b/lib/telnet.c
@@ -192,6 +192,7 @@ const struct Curl_handler Curl_handler_telnet = {
   ZERO_NULL,                            /* perform_getsock */
   ZERO_NULL,                            /* disconnect */
   ZERO_NULL,                            /* readwrite */
+  ZERO_NULL,                            /* connection_check */
   PORT_TELNET,                          /* defport */
   CURLPROTO_TELNET,                     /* protocol */
   PROTOPT_NONE | PROTOPT_NOURLQUERY     /* flags */
diff --git a/lib/tftp.c b/lib/tftp.c
index b2b3efe0c..336beb512 100644
--- a/lib/tftp.c
+++ b/lib/tftp.c
@@ -181,6 +181,7 @@ const struct Curl_handler Curl_handler_tftp = {
   ZERO_NULL,                            /* perform_getsock */
   tftp_disconnect,                      /* disconnect */
   ZERO_NULL,                            /* readwrite */
+  ZERO_NULL,                            /* connection_check */
   PORT_TFTP,                            /* defport */
   CURLPROTO_TFTP,                       /* protocol */
   PROTOPT_NONE | PROTOPT_NOURLQUERY     /* flags */
diff --git a/lib/url.c b/lib/url.c
index 07bdea129..e4aa515be 100644
--- a/lib/url.c
+++ b/lib/url.c
@@ -274,6 +274,7 @@ static const struct Curl_handler Curl_handler_dummy = {
   ZERO_NULL,                            /* perform_getsock */
   ZERO_NULL,                            /* disconnect */
   ZERO_NULL,                            /* readwrite */
+  ZERO_NULL,                            /* connection_check */
   0,                                    /* defport */
   0,                                    /* protocol */
   PROTOPT_NONE                          /* flags */
@@ -3379,11 +3380,19 @@ static bool disconnect_if_dead(struct connectdata *conn,
        handles in pipeline and the connection isn't already marked in
        use */
     bool dead;
-    if(conn->handler->protocol & CURLPROTO_RTSP)
-      /* RTSP is a special case due to RTP interleaving */
-      dead = Curl_rtsp_connisdead(conn);
-    else
+
+    if(conn->handler->connection_check) {
+      /* The protocol has a special method for checking the state of the
+         connection. Use it to check if the connection is dead. */
+      unsigned int state;
+
+      state = conn->handler->connection_check(conn, CONNCHECK_ISDEAD);
+      dead = (state & CONNRESULT_DEAD);
+    }
+    else {
+      /* Use the general method for determining the death of a connection */
       dead = SocketIsDead(conn->sock[FIRSTSOCKET]);
+    }
 
     if(dead) {
       conn->data = data;
diff --git a/lib/urldata.h b/lib/urldata.h
index e89d1d706..41f9408ba 100644
--- a/lib/urldata.h
+++ b/lib/urldata.h
@@ -829,6 +829,12 @@ struct Curl_handler {
   CURLcode (*readwrite)(struct Curl_easy *data, struct connectdata *conn,
                         ssize_t *nread, bool *readmore);
 
+  /* This function can perform various checks on the connection. See
+     CONNCHECK_* for more information about the checks that can be performed,
+     and CONNRESULT_* for the results that can be returned. */
+  unsigned int (*connection_check)(struct connectdata *conn,
+                                   unsigned int checks_to_perform);
+
   long defport;           /* Default port. */
   unsigned int protocol;  /* See CURLPROTO_* - this needs to be the single
                              specific protocol bit */
@@ -859,6 +865,12 @@ struct Curl_handler {
                                          HTTP proxy as HTTP proxies may know
                                          this protocol and act as a gateway */
 
+#define CONNCHECK_NONE 0                 /* No checks */
+#define CONNCHECK_ISDEAD (1<<0)          /* Check if the connection is dead. */
+
+#define CONNRESULT_NONE 0                /* No extra information. */
+#define CONNRESULT_DEAD (1<<0)           /* The connection is dead. */
+
 /* return the count of bytes sent, or -1 on error */
 typedef ssize_t (Curl_send)(struct connectdata *conn, /* connection data */
                             int sockindex,            /* socketindex */