Merge branch 'tb/http-curl-keepalive'

TCP keepalive behaviour on http transports can now be configured by
calling cURL library.

* tb/http-curl-keepalive:
  http.c: allow custom TCP keepalive behavior via config
  http.c: inline `set_curl_keepalive()`
  http.c: introduce `set_long_from_env()` for convenience
  http.c: remove unnecessary casts to long

Documentation/config/http.adoc

@@ -296,6 +296,24 @@ http.lowSpeedLimit, http.lowSpeedTime::
 	Can be overridden by the `GIT_HTTP_LOW_SPEED_LIMIT` and
 	`GIT_HTTP_LOW_SPEED_TIME` environment variables.
 
+http.keepAliveIdle::
+	Specifies how long in seconds to wait on an idle connection
+	before sending TCP keepalive probes (if supported by the OS). If
+	unset, curl's default value is used. Can be overridden by the
+	`GIT_HTTP_KEEPALIVE_IDLE` environment variable.
+
+http.keepAliveInterval::
+	Specifies how long in seconds to wait between TCP keepalive
+	probes (if supported by the OS). If unset, curl's default value
+	is used. Can be overridden by the `GIT_HTTP_KEEPALIVE_INTERVAL`
+	environment variable.
+
+http.keepAliveCount::
+	Specifies how many TCP keepalive probes to send before giving up
+	and terminating the connection (if supported by the OS). If
+	unset, curl's default value is used. Can be overridden by the
+	`GIT_HTTP_KEEPALIVE_COUNT` environment variable.
+
 http.noEPSV::
 	A boolean which disables using of EPSV ftp command by curl.
 	This can be helpful with some "poor" ftp servers which don't

git-curl-compat.h

@@ -45,4 +45,11 @@
 #define GIT_CURL_HAVE_CURLOPT_PROTOCOLS_STR 1
 #endif
 
+/**
+ * CURLOPT_TCP_KEEPCNT was added in 8.9.0, released in July, 2024.
+ */
+#if LIBCURL_VERSION_NUM >= 0x080900
+#define GIT_CURL_HAVE_CURLOPT_TCP_KEEPCNT
+#endif
+
 #endif

http.c

@@ -104,6 +104,10 @@ static struct {
 };
 #endif
 
+static long curl_tcp_keepidle = -1;
+static long curl_tcp_keepintvl = -1;
+static long curl_tcp_keepcnt = -1;
+
 enum proactive_auth {
 	PROACTIVE_AUTH_NONE = 0,
 	PROACTIVE_AUTH_IF_CREDENTIALS,
@@ -438,11 +442,11 @@ static int http_options(const char *var, const char *value,
 		return 0;
 	}
 	if (!strcmp("http.lowspeedlimit", var)) {
-		curl_low_speed_limit = (long)git_config_int(var, value, ctx->kvi);
+		curl_low_speed_limit = git_config_int(var, value, ctx->kvi);
 		return 0;
 	}
 	if (!strcmp("http.lowspeedtime", var)) {
-		curl_low_speed_time = (long)git_config_int(var, value, ctx->kvi);
+		curl_low_speed_time = git_config_int(var, value, ctx->kvi);
 		return 0;
 	}
 
@@ -557,6 +561,19 @@ static int http_options(const char *var, const char *value,
 		return 0;
 	}
 
+	if (!strcmp("http.keepaliveidle", var)) {
+		curl_tcp_keepidle = git_config_int(var, value, ctx->kvi);
+		return 0;
+	}
+	if (!strcmp("http.keepaliveinterval", var)) {
+		curl_tcp_keepintvl = git_config_int(var, value, ctx->kvi);
+		return 0;
+	}
+	if (!strcmp("http.keepalivecount", var)) {
+		curl_tcp_keepcnt = git_config_int(var, value, ctx->kvi);
+		return 0;
+	}
+
 	/* Fall back on the default ones */
 	return git_default_config(var, value, ctx, data);
 }
@@ -704,11 +721,6 @@ static int has_proxy_cert_password(void)
 	return 1;
 }
 
-static void set_curl_keepalive(CURL *c)
-{
-	curl_easy_setopt(c, CURLOPT_TCP_KEEPALIVE, 1);
-}
-
 /* Return 1 if redactions have been made, 0 otherwise. */
 static int redact_sensitive_header(struct strbuf *header, size_t offset)
 {
@@ -1242,7 +1254,18 @@ static CURL *get_curl_handle(void)
 	}
 	init_curl_proxy_auth(result);
 
-	set_curl_keepalive(result);
+	curl_easy_setopt(result, CURLOPT_TCP_KEEPALIVE, 1);
+
+	if (curl_tcp_keepidle > -1)
+		curl_easy_setopt(result, CURLOPT_TCP_KEEPIDLE,
+				 curl_tcp_keepidle);
+	if (curl_tcp_keepintvl > -1)
+		curl_easy_setopt(result, CURLOPT_TCP_KEEPINTVL,
+				 curl_tcp_keepintvl);
+#ifdef GIT_CURL_HAVE_CURLOPT_TCP_KEEPCNT
+	if (curl_tcp_keepcnt > -1)
+		curl_easy_setopt(result, CURLOPT_TCP_KEEPCNT, curl_tcp_keepcnt);
+#endif
 
 	return result;
 }
@@ -1256,10 +1279,30 @@ static void set_from_env(char **var, const char *envname)
 	}
 }
 
+static void set_long_from_env(long *var, const char *envname)
+{
+	const char *val = getenv(envname);
+	if (val) {
+		long tmp;
+		char *endp;
+		int saved_errno = errno;
+
+		errno = 0;
+		tmp = strtol(val, &endp, 10);
+
+		if (errno)
+			warning_errno(_("failed to parse %s"), envname);
+		else if (*endp || endp == val)
+			warning(_("failed to parse %s"), envname);
+		else
+			*var = tmp;
+
+		errno = saved_errno;
+	}
+}
+
 void http_init(struct remote *remote, const char *url, int proactive_auth)
 {
-	char *low_speed_limit;
-	char *low_speed_time;
 	char *normalized_url;
 	struct urlmatch_config config = URLMATCH_CONFIG_INIT;
 
@@ -1338,12 +1381,8 @@ void http_init(struct remote *remote, const char *url, int proactive_auth)
 
 	set_from_env(&user_agent, "GIT_HTTP_USER_AGENT");
 
-	low_speed_limit = getenv("GIT_HTTP_LOW_SPEED_LIMIT");
-	if (low_speed_limit)
-		curl_low_speed_limit = strtol(low_speed_limit, NULL, 10);
-	low_speed_time = getenv("GIT_HTTP_LOW_SPEED_TIME");
-	if (low_speed_time)
-		curl_low_speed_time = strtol(low_speed_time, NULL, 10);
+	set_long_from_env(&curl_low_speed_limit, "GIT_HTTP_LOW_SPEED_LIMIT");
+	set_long_from_env(&curl_low_speed_time, "GIT_HTTP_LOW_SPEED_TIME");
 
 	if (curl_ssl_verify == -1)
 		curl_ssl_verify = 1;
@@ -1370,6 +1409,10 @@ void http_init(struct remote *remote, const char *url, int proactive_auth)
 			ssl_cert_password_required = 1;
 	}
 
+	set_long_from_env(&curl_tcp_keepidle, "GIT_TCP_KEEPIDLE");
+	set_long_from_env(&curl_tcp_keepintvl, "GIT_TCP_KEEPINTVL");
+	set_long_from_env(&curl_tcp_keepcnt, "GIT_TCP_KEEPCNT");
+
 	curl_default = get_curl_handle();
 }