added support for curl --retry

Author: fack

rustup-init.sh

@@ -473,6 +473,7 @@ downloader() {
     local _ciphersuites
     local _err
     local _status
+    local _retry
     if check_cmd curl; then
         _dld=curl
     elif check_cmd wget; then
@@ -484,10 +485,12 @@ downloader() {
     if [ "$1" = --check ]; then
         need_cmd "$_dld"
     elif [ "$_dld" = curl ]; then
+        check_curl_for_retry_support
+        _retry="$RETVAL"
         get_ciphersuites_for_curl
         _ciphersuites="$RETVAL"
         if [ -n "$_ciphersuites" ]; then
-            _err=$(curl --proto '=https' --tlsv1.2 --ciphers "$_ciphersuites" --silent --show-error --fail --location "$1" --output "$2" 2>&1)
+            _err=$(curl $_retry --proto '=https' --tlsv1.2 --ciphers "$_ciphersuites" --silent --show-error --fail --location "$1" --output "$2" 2>&1)
             _status=$?
         else
             echo "Warning: Not enforcing strong cipher suites for TLS, this is potentially less secure"
@@ -589,8 +592,19 @@ check_help_for() {
     true # not strictly needed
 }
 
+# Check if curl supports the --retry flag, then pass it to the curl invocation.
+check_curl_for_retry_support() {
+  # "unspecified" is for arch, allows for possibility old OS using macports, homebrew, etc.
+  if check_help_for "notspecified" "curl" "--retry"; then
+    local _retry_supported="--retry 3"
+  fi
+
+  RETVAL="$_retry_supported"
+
+}
+
 # Return cipher suite string specified by user, otherwise return strong TLS 1.2-1.3 cipher suites
-# if support by local tools is detected. Detection currently supports these curl backends: 
+# if support by local tools is detected. Detection currently supports these curl backends:
 # GnuTLS and OpenSSL (possibly also LibreSSL and BoringSSL). Return value can be empty.
 get_ciphersuites_for_curl() {
     if [ -n "${RUSTUP_TLS_CIPHERSUITES-}" ]; then
@@ -635,7 +649,7 @@ get_ciphersuites_for_curl() {
 }
 
 # Return cipher suite string specified by user, otherwise return strong TLS 1.2-1.3 cipher suites
-# if support by local tools is detected. Detection currently supports these wget backends: 
+# if support by local tools is detected. Detection currently supports these wget backends:
 # GnuTLS and OpenSSL (possibly also LibreSSL and BoringSSL). Return value can be empty.
 get_ciphersuites_for_wget() {
     if [ -n "${RUSTUP_TLS_CIPHERSUITES-}" ]; then
@@ -660,10 +674,10 @@ get_ciphersuites_for_wget() {
     RETVAL="$_cs"
 }
 
-# Return strong TLS 1.2-1.3 cipher suites in OpenSSL or GnuTLS syntax. TLS 1.2 
-# excludes non-ECDHE and non-AEAD cipher suites. DHE is excluded due to bad 
+# Return strong TLS 1.2-1.3 cipher suites in OpenSSL or GnuTLS syntax. TLS 1.2
+# excludes non-ECDHE and non-AEAD cipher suites. DHE is excluded due to bad
 # DH params often found on servers (see RFC 7919). Sequence matches or is
-# similar to Firefox 68 ESR with weak cipher suites disabled via about:config.  
+# similar to Firefox 68 ESR with weak cipher suites disabled via about:config.
 # $1 must be openssl or gnutls.
 get_strong_ciphersuites_for() {
     if [ "$1" = "openssl" ]; then
@@ -673,7 +687,7 @@ get_strong_ciphersuites_for() {
         # GnuTLS isn't forgiving of unknown values, so this may require a GnuTLS version that supports TLS 1.3 even if wget doesn't.
         # Begin with SECURE128 (and higher) then remove/add to build cipher suites. Produces same 9 cipher suites as OpenSSL but in slightly different order.
         echo "SECURE128:-VERS-SSL3.0:-VERS-TLS1.0:-VERS-TLS1.1:-VERS-DTLS-ALL:-CIPHER-ALL:-MAC-ALL:-KX-ALL:+AEAD:+ECDHE-ECDSA:+ECDHE-RSA:+AES-128-GCM:+CHACHA20-POLY1305:+AES-256-GCM"
-    fi 
+    fi
 }
 
 main "$@" || exit 1