From 4ba4cf4969f923c2f80a1a7fc3989e62ce6ba79e Mon Sep 17 00:00:00 2001
From: Sean McBride <spmcbride1201@gmail.com>
Date: Tue, 25 Jan 2022 17:40:52 +0000
Subject: [PATCH] feat: Add new HTTP codes

---
 runtime/include/http.h        | 66 +++++++++++++++++++++++------------
 runtime/src/listener_thread.c |  7 ++--
 2 files changed, 48 insertions(+), 25 deletions(-)

diff --git a/runtime/include/http.h b/runtime/include/http.h
index a0c0ac8..fc05dec 100644
--- a/runtime/include/http.h
+++ b/runtime/include/http.h
@@ -9,37 +9,47 @@
 #define HTTP_MAX_HEADER_LENGTH       32
 #define HTTP_MAX_HEADER_VALUE_LENGTH 64
 
+#define HTTP_RESPONSE_200_TEMPLATE \
+	"HTTP/1.1 200 OK\r\n"      \
+	"Server: SLEdge\r\n"       \
+	"Connection: close\r\n"    \
+	"Content-Type: %s\r\n"     \
+	"Content-Length: %lu\r\n"  \
+	"\r\n"
+
+/* The sum of format specifier characters in the template above */
+#define HTTP_RESPONSE_200_TEMPLATE_FORMAT_SPECIFIER_LENGTH 5
+
 #define HTTP_RESPONSE_400_BAD_REQUEST  \
 	"HTTP/1.1 400 Bad Request\r\n" \
 	"Server: SLEdge\r\n"           \
 	"Connection: close\r\n"        \
 	"\r\n"
 
-
 #define HTTP_RESPONSE_413_PAYLOAD_TOO_LARGE  \
 	"HTTP/1.1 413 Payload Too Large\r\n" \
 	"Server: SLEdge\r\n"                 \
 	"Connection: close\r\n"              \
 	"\r\n"
 
+#define HTTP_RESPONSE_429_TOO_MANY_REQUESTS  \
+	"HTTP/1.1 429 Too Many Requests\r\n" \
+	"Server: SLEdge\r\n"                 \
+	"Connection: close\r\n"              \
+	"\r\n"
+
+#define HTTP_RESPONSE_500_INTERNAL_SERVER_ERROR  \
+	"HTTP/1.1 500 Internal Server Error\r\n" \
+	"Server: SLEdge\r\n"                     \
+	"Connection: close\r\n"                  \
+	"\r\n"
+
 #define HTTP_RESPONSE_503_SERVICE_UNAVAILABLE  \
 	"HTTP/1.1 503 Service Unavailable\r\n" \
 	"Server: SLEdge\r\n"                   \
 	"Connection: close\r\n"                \
 	"\r\n"
 
-#define HTTP_RESPONSE_200_TEMPLATE \
-	"HTTP/1.1 200 OK\r\n"      \
-	"Server: SLEdge\r\n"       \
-	"Connection: close\r\n"    \
-	"Content-Type: %s\r\n"     \
-	"Content-Length: %lu\r\n"  \
-	"\r\n"
-
-/* The sum of format specifier characters in the template above */
-#define HTTP_RESPONSE_200_TEMPLATE_FORMAT_SPECIFIER_LENGTH 5
-
-
 static inline int
 http_header_200_write(int fd, const char *content_type, size_t content_length)
 {
@@ -52,18 +62,26 @@ http_header_build(int status_code)
 	const char *response;
 	int         rc;
 	switch (status_code) {
-	case 503:
-		response = HTTP_RESPONSE_503_SERVICE_UNAVAILABLE;
-		http_total_increment_5XX();
+	case 400:
+		response = HTTP_RESPONSE_400_BAD_REQUEST;
+		http_total_increment_4XX();
 		break;
 	case 413:
 		response = HTTP_RESPONSE_413_PAYLOAD_TOO_LARGE;
 		http_total_increment_4XX();
 		break;
-	case 400:
-		response = HTTP_RESPONSE_400_BAD_REQUEST;
+	case 429:
+		response = HTTP_RESPONSE_429_TOO_MANY_REQUESTS;
 		http_total_increment_4XX();
 		break;
+	case 500:
+		response = HTTP_RESPONSE_500_INTERNAL_SERVER_ERROR;
+		http_total_increment_5XX();
+		break;
+	case 503:
+		response = HTTP_RESPONSE_503_SERVICE_UNAVAILABLE;
+		http_total_increment_5XX();
+		break;
 	default:
 		panic("%d is not a valid status code\n", status_code);
 	}
@@ -75,12 +93,16 @@ static inline int
 http_header_len(int status_code)
 {
 	switch (status_code) {
-	case 503:
-		return strlen(HTTP_RESPONSE_503_SERVICE_UNAVAILABLE);
-	case 413:
-		return strlen(HTTP_RESPONSE_413_PAYLOAD_TOO_LARGE);
 	case 400:
 		return strlen(HTTP_RESPONSE_400_BAD_REQUEST);
+	case 413:
+		return strlen(HTTP_RESPONSE_413_PAYLOAD_TOO_LARGE);
+	case 429:
+		return strlen(HTTP_RESPONSE_429_TOO_MANY_REQUESTS);
+	case 500:
+		return strlen(HTTP_RESPONSE_500_INTERNAL_SERVER_ERROR);
+	case 503:
+		return strlen(HTTP_RESPONSE_503_SERVICE_UNAVAILABLE);
 	default:
 		panic("%d is not a valid status code\n", status_code);
 	}
diff --git a/runtime/src/listener_thread.c b/runtime/src/listener_thread.c
index e4b2da6..9ab1826 100644
--- a/runtime/src/listener_thread.c
+++ b/runtime/src/listener_thread.c
@@ -166,12 +166,13 @@ listener_thread_main(void *dummy)
 
 				/*
 				 * Perform admissions control.
-				 * If 0, workload was rejected, so close with 503 and continue
+				 * If 0, workload was rejected, so close with 429 "Too Many Requests" and continue
+				 * TODO: Consider providing a Retry-After header
 				 */
 				uint64_t work_admitted = admissions_control_decide(module->admissions_info.estimate);
 				if (work_admitted == 0) {
-					client_socket_send_oneshot(client_socket, http_header_build(503),
-					                           http_header_len(503));
+					client_socket_send_oneshot(client_socket, http_header_build(429),
+					                           http_header_len(429));
 					if (unlikely(close(client_socket) < 0))
 						debuglog("Error closing client socket - %s", strerror(errno));