[PATCH] http-backend: respect CONTENT_LENGTH as specified by rfc3875

From

Max Kirillov <max@max630.net>

Date

Nov 23, 2017, 23:45 UTC

Message-ID

<20171123234511.574-1-max@max630.net>

In-Reply-To

<20160401235532.GA27941@sigill.intra.peff.net>

Signed-off-by: Florian Manschwetus <manschwetus@cs-software-gmbh.de>
Authored-by: Florian Manschwetus <manschwetus@cs-software-gmbh.de>
Fixed-by: Max Kirillov <max@max630.net>
Signed-off-by: Max Kirillov <max@max630.net>
---
Hi

I came across this issue, and I think is should be good to restore the patch.
It is basically same but I squashed them, fixed the thing you mentioned and
also some trivial build failures (null -> NULL and missing return from the wrapper).
I hope I marked it correctly in the trailers.
 config.c       |  8 +++++++
 config.h       |  1 +
 http-backend.c | 72 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 3 files changed, 80 insertions(+), 1 deletion(-)

diff --git a/config.c b/config.c
index 231f9a750b..925bb65dfa 100644
--- a/config.c
+++ b/config.c
@@ -1525,6 +1525,14 @@ unsigned long git_env_ulong(const char *k, unsigned long val)
 	return val;
 }
 
+ssize_t git_env_ssize_t(const char *k, ssize_t val)
+{
+	const char *v = getenv(k);
+	if (v && !git_parse_ssize_t(v, &val))
+		die("failed to parse %s", k);
+	return val;
+}
+
 int git_config_system(void)
 {
 	return !git_env_bool("GIT_CONFIG_NOSYSTEM", 0);
diff --git a/config.h b/config.h
index 0352da117b..947695c304 100644
--- a/config.h
+++ b/config.h
@@ -74,6 +74,7 @@ extern int git_config_rename_section_in_file(const char *, const char *, const c
 extern const char *git_etc_gitconfig(void);
 extern int git_env_bool(const char *, int);
 extern unsigned long git_env_ulong(const char *, unsigned long);
+extern ssize_t git_env_ssize_t(const char *, ssize_t);
 extern int git_config_system(void);
 extern int config_error_nonbool(const char *);
 #if defined(__GNUC__)
diff --git a/http-backend.c b/http-backend.c
index 519025d2c3..317b99b87c 100644
--- a/http-backend.c
+++ b/http-backend.c
@@ -280,7 +280,7 @@ static struct rpc_service *select_service(struct strbuf *hdr, const char *name)
  * hit max_request_buffer we die (we'd rather reject a
  * maliciously large request than chew up infinite memory).
  */
-static ssize_t read_request(int fd, unsigned char **out)
+static ssize_t read_request_eof(int fd, unsigned char **out)
 {
 	size_t len = 0, alloc = 8192;
 	unsigned char *buf = xmalloc(alloc);
@@ -317,6 +317,76 @@ static ssize_t read_request(int fd, unsigned char **out)
 	}
 }
 
+/*
+ * replacement for original read_request, now renamed to read_request_eof,
+ * honoring given content_length (req_len),
+ * provided by new wrapper function read_request
+ */
+static ssize_t read_request_fix_len(int fd, size_t req_len, unsigned char **out)
+{
+	unsigned char *buf = NULL;
+	size_t len = 0;
+
+	/* check request size */
+	if (max_request_buffer < req_len) {
+		die("request was larger than our maximum size (%lu);"
+			    " try setting GIT_HTTP_MAX_REQUEST_BUFFER",
+			    max_request_buffer);
+	}
+
+	if (req_len <= 0) {
+		*out = NULL;
+		return 0;
+	}
+
+	/* allocate buffer */
+	buf = xmalloc(req_len);
+
+
+	while (1) {
+		ssize_t cnt;
+
+		cnt = read_in_full(fd, buf + len, req_len - len);
+		if (cnt < 0) {
+			free(buf);
+			return -1;
+		}
+
+		/* partial read from read_in_full means we hit EOF */
+		len += cnt;
+		if (len < req_len) {
+			/* TODO request incomplete?? */
+			/* maybe just remove this block and condition along with the loop, */
+			/* if read_in_full is prooven reliable */
+			*out = buf;
+			return len;
+		} else {
+			/* request complete */
+			*out = buf;
+			return len;
+			
+		}
+	}
+}
+
+/**
+ * wrapper function, whcih determines based on CONTENT_LENGTH value,
+ * to
+ * - use old behaviour of read_request, to read until EOF
+ * => read_request_eof(...)
+ * - just read CONTENT_LENGTH-bytes, when provided
+ * => read_request_fix_len(...)
+ */
+static ssize_t read_request(int fd, unsigned char **out)
+{
+	/* get request size */
+	ssize_t req_len = git_env_ssize_t("CONTENT_LENGTH", -1);
+	if (req_len < 0)
+		return read_request_eof(fd, out);
+	else
+		return read_request_fix_len(fd, req_len, out);
+}
+
 static void inflate_request(const char *prog_name, int out, int buffer_input)
 {
 	git_zstream stream;

-- 
2.11.0.1122.gc3fec58.dirty