[PATCH v3 2/2] http: redact curl h2h3 headers in info

["Glen Choo via GitGitGadget" <gitgitgadget@gmail.com>]

From: Glen Choo <chooglen@google.com>

With GIT_TRACE_CURL=1 or GIT_CURL_VERBOSE=1, sensitive headers like
"Authorization" and "Cookie" get redacted. However, since [1], curl's
h2h3 module (invoked when using HTTP/2) also prints headers in its
"info", which don't get redacted. For example,

  echo 'github.com	TRUE	/	FALSE	1698960413304	o	foo=bar' >cookiefile &&
  GIT_TRACE_CURL=1 GIT_TRACE_CURL_NO_DATA=1 git \
    -c 'http.cookiefile=cookiefile' \
    -c 'http.version=' \
    ls-remote https://github.com/git/git refs/heads/main 2>output &&
  grep 'cookie' output

produces output like:

  23:04:16.920495 http.c:678              == Info: h2h3 [cookie: o=foo=bar]
  23:04:16.920562 http.c:637              => Send header: cookie: o=<redacted>

Teach http.c to check for h2h3 headers in info and redact them using the
existing header redaction logic. This fixes the broken redaction logic
that we noted in the previous commit, so mark the redaction tests as
passing under HTTP2.

[1] https://github.com/curl/curl/commit/f8c3724aa90472c0e617ddbbc420aa199971eb77

Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Glen Choo <chooglen@google.com>
---
 http.c                      | 47 ++++++++++++++++++++++++++++++++-----
 t/t5551-http-fetch-smart.sh |  6 ++---
 2 files changed, 44 insertions(+), 9 deletions(-)

diff --git a/http.c b/http.c
index 5d0502f51fd..8a5ba3f4776 100644
--- a/http.c
+++ b/http.c
@@ -560,13 +560,15 @@ static void set_curl_keepalive(CURL *c)
 }
 #endif
 
-static void redact_sensitive_header(struct strbuf *header)
+/* Return 1 if redactions have been made, 0 otherwise. */
+static int redact_sensitive_header(struct strbuf *header, size_t offset)
 {
+	int ret = 0;
 	const char *sensitive_header;
 
 	if (trace_curl_redact &&
-	    (skip_iprefix(header->buf, "Authorization:", &sensitive_header) ||
-	     skip_iprefix(header->buf, "Proxy-Authorization:", &sensitive_header))) {
+	    (skip_iprefix(header->buf + offset, "Authorization:", &sensitive_header) ||
+	     skip_iprefix(header->buf + offset, "Proxy-Authorization:", &sensitive_header))) {
 		/* The first token is the type, which is OK to log */
 		while (isspace(*sensitive_header))
 			sensitive_header++;
@@ -575,8 +577,9 @@ static void redact_sensitive_header(struct strbuf *header)
 		/* Everything else is opaque and possibly sensitive */
 		strbuf_setlen(header,  sensitive_header - header->buf);
 		strbuf_addstr(header, " <redacted>");
+		ret = 1;
 	} else if (trace_curl_redact &&
-		   skip_iprefix(header->buf, "Cookie:", &sensitive_header)) {
+		   skip_iprefix(header->buf + offset, "Cookie:", &sensitive_header)) {
 		struct strbuf redacted_header = STRBUF_INIT;
 		const char *cookie;
 
@@ -612,6 +615,26 @@ static void redact_sensitive_header(struct strbuf *header)
 
 		strbuf_setlen(header, sensitive_header - header->buf);
 		strbuf_addbuf(header, &redacted_header);
+		ret = 1;
+	}
+	return ret;
+}
+
+/* Redact headers in info */
+static void redact_sensitive_info_header(struct strbuf *header)
+{
+	const char *sensitive_header;
+
+	/*
+	 * curl's h2h3 prints headers in info, e.g.:
+	 *   h2h3 [<header-name>: <header-val>]
+	 */
+	if (trace_curl_redact &&
+	    skip_iprefix(header->buf, "h2h3 [", &sensitive_header)) {
+		if (redact_sensitive_header(header, sensitive_header - header->buf)) {
+			/* redaction ate our closing bracket */
+			strbuf_addch(header, ']');
+		}
 	}
 }
 
@@ -629,7 +652,7 @@ static void curl_dump_header(const char *text, unsigned char *ptr, size_t size,
 
 	for (header = headers; *header; header++) {
 		if (hide_sensitive_header)
-			redact_sensitive_header(*header);
+			redact_sensitive_header(*header, 0);
 		strbuf_insertstr((*header), 0, text);
 		strbuf_insertstr((*header), strlen(text), ": ");
 		strbuf_rtrim((*header));
@@ -668,6 +691,18 @@ static void curl_dump_data(const char *text, unsigned char *ptr, size_t size)
 	strbuf_release(&out);
 }
 
+static void curl_dump_info(char *data, size_t size)
+{
+	struct strbuf buf = STRBUF_INIT;
+
+	strbuf_add(&buf, data, size);
+
+	redact_sensitive_info_header(&buf);
+	trace_printf_key(&trace_curl, "== Info: %s", buf.buf);
+
+	strbuf_release(&buf);
+}
+
 static int curl_trace(CURL *handle, curl_infotype type, char *data, size_t size, void *userp)
 {
 	const char *text;
@@ -675,7 +710,7 @@ static int curl_trace(CURL *handle, curl_infotype type, char *data, size_t size,
 
 	switch (type) {
 	case CURLINFO_TEXT:
-		trace_printf_key(&trace_curl, "== Info: %s", data);
+		curl_dump_info(data, size);
 		break;
 	case CURLINFO_HEADER_OUT:
 		text = "=> Send header";
diff --git a/t/t5551-http-fetch-smart.sh b/t/t5551-http-fetch-smart.sh
index ad0a0639e6b..a2ebce1787b 100755
--- a/t/t5551-http-fetch-smart.sh
+++ b/t/t5551-http-fetch-smart.sh
@@ -200,7 +200,7 @@ test_expect_success 'redirects send auth to new location' '
 	expect_askpass both user@host auth/smart/repo.git
 '
 
-test_expect_success !HTTP2 'GIT_TRACE_CURL redacts auth details' '
+test_expect_success 'GIT_TRACE_CURL redacts auth details' '
 	rm -rf redact-auth trace &&
 	set_askpass user@host pass@host &&
 	GIT_TRACE_CURL="$(pwd)/trace" git clone --bare "$HTTPD_URL/auth/smart/repo.git" redact-auth &&
@@ -212,7 +212,7 @@ test_expect_success !HTTP2 'GIT_TRACE_CURL redacts auth details' '
 	grep -i "Authorization: Basic <redacted>" trace
 '
 
-test_expect_success !HTTP2 'GIT_CURL_VERBOSE redacts auth details' '
+test_expect_success 'GIT_CURL_VERBOSE redacts auth details' '
 	rm -rf redact-auth trace &&
 	set_askpass user@host pass@host &&
 	GIT_CURL_VERBOSE=1 git clone --bare "$HTTPD_URL/auth/smart/repo.git" redact-auth 2>trace &&
@@ -482,7 +482,7 @@ test_expect_success 'fetch by SHA-1 without tag following' '
 		--no-tags origin $(cat bar_hash)
 '
 
-test_expect_success !HTTP2 'cookies are redacted by default' '
+test_expect_success 'cookies are redacted by default' '
 	rm -rf clone &&
 	echo "Set-Cookie: Foo=1" >cookies &&
 	echo "Set-Cookie: Bar=2" >>cookies &&
-- 
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