Add extra check to _response for "100 Continue" HTTP response

This is a very simple check that only accounts for *one*
extra "100 Continue" HTTP response. It simpy reads once,
checks for status 100 and reads again, discarding everything
after the "Continue" response.
Not very clean, more of a proof of concept.

ok.sh

@@ -769,6 +769,22 @@ _response() {
 
     _log debug "Response status is: ${status_code} ${status_text}"
 
+    if [ "${status_code}" = "100" ]; then
+        _log debug "Ignoring response '${status_code} ${status_text}', skipping to real response."
+        while IFS=": " read -r hdr val; do
+            # Headers stop at the first blank line.
+            [ "$hdr" = "$crlf" ] && break
+            val="${val%${crlf}}"
+            _log debug "Unexpected additional header: ${hdr}: ${val}"
+        done
+
+        read -r http_version status_code status_text
+        status_text="${status_text%${crlf}}"
+        http_version="${http_version#HTTP/}"
+
+        _log debug "Response status is: ${status_code} ${status_text}"
+    fi
+
     headers="http_version: ${http_version}
 status_code: ${status_code}
 status_text: ${status_text}

tests/unit.sh

@@ -166,4 +166,24 @@ Hi\n' | $SCRIPT _response Baz Bad Foo | {
     }
 }
 
+test_response_headers_100_continue() {
+    # Test that process response 100 Continue is handled correctly.
+
+    local baz bar foo
+
+    printf 'HTTP/1.1 100 Continue\r\n\r\nHTTP/1.1 200 OK\r\nServer: example.com\r\nFoo: Foo!\r\nBar: Bar!\r\nBaz: Baz!\r\n\r\nHi
+' | $SCRIPT _response Baz Bad Foo | {
+        read -r baz
+        read -r bar     # Ensure unfound items are blank.
+        read -r foo
+
+        ret=0
+        [ "$baz" = 'Baz!' ] || { ret=1; printf '`Baz!` != `%s`\n' "$baz"; }
+        [ "$bar" = '' ] || { ret=1; printf '`` != `%s`\n' "$bar"; }
+        [ "$foo" = 'Foo!' ] || { ret=1; printf '`Foo!` != `%s`\n' "$foo"; }
+
+        return $ret
+    }
+}
+
 _main "$@"