[PATCH 3/3] http.c: allow custom TCP keepalive behavior via config
- From
Taylor Blau <me@ttaylorr.com>
- Date
- Mar 18, 2025, 22:21 UTC
- Message-ID
- <d84041580895a653648ee2370e21d7d2aa4fc4bb.1742336481.git.me@ttaylorr.com>
- In-Reply-To
- <cover.1742336481.git.me@ttaylorr.com>
curl supports a few options to control when and how often it should instruct the OS to send TCP keepalives, like KEEPIDLE, KEEPINTVL, and KEEPCNT. Until this point, there hasn't been a way for users to change what values are used for these options, forcing them to rely on curl's defaults.
But we do unconditionally enable TCP keepalives without giving users an ability to tweak any fine-grained parameters. Ordinarily this isn't a problem, particularly for users that have fast-enough connections, and/or are talking to a server that has generous or nonexistent thresholds for killing a connection it hasn't heard from in a while.
But it can present a problem when one or both of those assumptions fail. For instance, I can reliably get an in-progress clone to be killed from the remote end when cloning from some forges while using trickle to limit my clone's bandwidth.
For those users and others who wish to more finely tune the OS's keepalive behavior, expose configuration and environment variables which allow setting curl's KEEPIDLE, KEEPINTVL, and KEEPCNT options.
Signed-off-by: Taylor Blau <me@ttaylorr.com> --- Documentation/config/http.adoc | 18 ++++++++++++++++++ http.c | 31 ++++++++++++++++++++++++++++++- 2 files changed, 48 insertions(+), 1 deletion(-)
diff --git a/Documentation/config/http.adoc b/Documentation/config/http.adoc index 22a8803dea..67393282fa 100644 --- a/Documentation/config/http.adoc +++ b/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 diff --git a/http.c b/http.c index 526f9680f9..c13c7da530 100644 --- a/http.c +++ b/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, @@ -557,6 +561,19 @@ static int http_options(const char *var, const char *value, return 0; } + if (!strcmp("http.keepaliveidle", var)) { + curl_tcp_keepidle = (long)git_config_int(var, value, ctx->kvi); + return 0; + } + if (!strcmp("http.keepaliveinterval", var)) { + curl_tcp_keepintvl = (long)git_config_int(var, value, ctx->kvi); + return 0; + } + if (!strcmp("http.keepalivecount", var)) { + curl_tcp_keepcnt = (long)git_config_int(var, value, ctx->kvi); + return 0; + } + /* Fall back on the default ones */ return git_default_config(var, value, ctx, data); } @@ -704,7 +721,6 @@ static int has_proxy_cert_password(void) return 1; } - /* Return 1 if redactions have been made, 0 otherwise. */ static int redact_sensitive_header(struct strbuf *header, size_t offset) { @@ -1240,6 +1256,15 @@ static CURL *get_curl_handle(void) 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); + if (curl_tcp_keepcnt > -1) + curl_easy_setopt(result, CURLOPT_TCP_KEEPCNT, curl_tcp_keepcnt); + return result; } @@ -1367,6 +1392,10 @@ 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(); }
-- 2.49.0.3.gbb7a4a684c.dirty