fshttp: add --expect-continue-timeout default 1s - fixes #3835

Before this change the expect/continue timeout was set to
--conntimeout which was 60s by default which is too long to wait.

This was noticed when using s3 with a proxy which apparently didn't
support expect / continue properly.

Set --expect-continue-timeout 0 to disable expect/continue.

docs/content/docs.md

@@ -539,6 +539,19 @@ Do a trial run with no permanent changes.  Use this to see what rclone
 would do without actually doing it.  Useful when setting up the `sync`
 command which deletes files in the destination.
 
+### --expect-continue-timeout=TIME ###
+
+This specifies the amount of time to wait for a server's first
+response headers after fully writing the request headers if the
+request has an "Expect: 100-continue" header. Not all backends support
+using this.
+
+Zero means no timeout and causes the body to be sent immediately,
+without waiting for the server to approve.  This time does not include
+the time to send the request header.
+
+The default is `1s`.  Set to 0 to disable.
+
 ### --ignore-case-sync ###
 
 Using this option will cause rclone to ignore the case of the files 

fs/config.go

@@ -54,6 +54,7 @@ type ConfigInfo struct {
 	Transfers              int
 	ConnectTimeout         time.Duration // Connect timeout
 	Timeout                time.Duration // Data channel timeout
+	ExpectContinueTimeout  time.Duration
 	Dump                   DumpFlags
 	InsecureSkipVerify     bool // Skip server certificate verification
 	DeleteMode             DeleteMode
@@ -121,6 +122,7 @@ func NewConfig() *ConfigInfo {
 	c.Transfers = 4
 	c.ConnectTimeout = 60 * time.Second
 	c.Timeout = 5 * 60 * time.Second
+	c.ExpectContinueTimeout = 1 * time.Second
 	c.DeleteMode = DeleteModeDefault
 	c.MaxDelete = -1
 	c.LowLevelRetries = 10

fs/config/configflags/configflags.go

@@ -50,6 +50,7 @@ func AddFlags(flagSet *pflag.FlagSet) {
 	flags.BoolVarP(flagSet, &fs.Config.DryRun, "dry-run", "n", fs.Config.DryRun, "Do a trial run with no permanent changes")
 	flags.DurationVarP(flagSet, &fs.Config.ConnectTimeout, "contimeout", "", fs.Config.ConnectTimeout, "Connect timeout")
 	flags.DurationVarP(flagSet, &fs.Config.Timeout, "timeout", "", fs.Config.Timeout, "IO idle timeout")
+	flags.DurationVarP(flagSet, &fs.Config.ExpectContinueTimeout, "expect-continue-timeout", "", fs.Config.ExpectContinueTimeout, "Timeout when using expect / 100-continue in HTTP")
 	flags.BoolVarP(flagSet, &dumpHeaders, "dump-headers", "", false, "Dump HTTP headers - may contain sensitive info")
 	flags.BoolVarP(flagSet, &dumpBodies, "dump-bodies", "", false, "Dump HTTP headers and bodies - may contain sensitive info")
 	flags.BoolVarP(flagSet, &fs.Config.InsecureSkipVerify, "no-check-certificate", "", fs.Config.InsecureSkipVerify, "Do not verify the server SSL certificate. Insecure.")

fs/fshttp/http.go

@@ -178,7 +178,7 @@ func NewTransportCustom(ci *fs.ConfigInfo, customize func(*http.Transport)) http
 		return dialContextTimeout(ctx, network, addr, ci)
 	}
 	t.IdleConnTimeout = 60 * time.Second
-	t.ExpectContinueTimeout = ci.ConnectTimeout
+	t.ExpectContinueTimeout = ci.ExpectContinueTimeout
 
 	// customize the transport if required
 	if customize != nil {