[Tarantool-patches] [PATCH 15/16] sio: introduce and use sio_snprintf()

[Vladislav Shpilevoy via Tarantool-patches <tarantool-patches@dev.tarantool.org>]

sio_strfaddr() can't be used in the places where static buffer
is not acceptable - in any code which wants to push the value to
Lua, or the address string must be long living.

The patch introduces sio_snprintf(), which does the same, but
saves the result into a provided buffer with a limited size.

In the Lua C code the patch saves the address string on the stack
which makes it safe against Lua GC interruptions.

Part of #5632
---
 src/box/iproto.cc     |  8 +++++---
 src/box/iproto.h      |  2 +-
 src/box/lua/info.c    |  5 +++--
 src/box/lua/session.c |  7 +++++--
 src/lib/core/sio.c    | 40 ++++++++++++++++++++++++++++------------
 src/lib/core/sio.h    |  4 ++++
 6 files changed, 46 insertions(+), 20 deletions(-)

diff --git a/src/box/iproto.cc b/src/box/iproto.cc
index f7330af21..238842e17 100644
--- a/src/box/iproto.cc
+++ b/src/box/iproto.cc
@@ -138,12 +138,14 @@ static struct sockaddr_storage iproto_bound_address_storage;
 static socklen_t iproto_bound_address_len;
 
 const char *
-iproto_bound_address(void)
+iproto_bound_address(char *buf)
 {
 	if (iproto_bound_address_len == 0)
 		return NULL;
-	return sio_strfaddr((struct sockaddr *) &iproto_bound_address_storage,
-			    iproto_bound_address_len);
+	sio_addr_snprintf(buf, SERVICE_NAME_MAXLEN,
+			  (struct sockaddr *) &iproto_bound_address_storage,
+			  iproto_bound_address_len);
+	return buf;
 }
 
 /**
diff --git a/src/box/iproto.h b/src/box/iproto.h
index 392e4f08e..f6f7101a1 100644
--- a/src/box/iproto.h
+++ b/src/box/iproto.h
@@ -85,7 +85,7 @@ iproto_reset_stat(void);
  * iproto. To be shown in box.info.
  */
 const char *
-iproto_bound_address(void);
+iproto_bound_address(char *buf);
 
 #if defined(__cplusplus)
 } /* extern "C" */
diff --git a/src/box/lua/info.c b/src/box/lua/info.c
index c4c9fa0a0..1e0c0148a 100644
--- a/src/box/lua/info.c
+++ b/src/box/lua/info.c
@@ -52,7 +52,7 @@
 #include "box/raft.h"
 #include "lua/utils.h"
 #include "fiber.h"
-#include "tt_static.h"
+#include "sio.h"
 
 static void
 lbox_pushvclock(struct lua_State *L, const struct vclock *vclock)
@@ -574,7 +574,8 @@ static int
 lbox_info_listen(struct lua_State *L)
 {
 	/* NULL is ok, no need to check. */
-	lua_pushstring(L, iproto_bound_address());
+	char addrbuf[SERVICE_NAME_MAXLEN];
+	lua_pushstring(L, iproto_bound_address(addrbuf));
 	return 1;
 }
 
diff --git a/src/box/lua/session.c b/src/box/lua/session.c
index 0a20aaad1..ae8c7094b 100644
--- a/src/box/lua/session.c
+++ b/src/box/lua/session.c
@@ -273,10 +273,13 @@ lbox_session_peer(struct lua_State *L)
 
 	struct sockaddr_storage addr;
 	socklen_t addrlen = sizeof(addr);
-	if (sio_getpeername(fd, (struct sockaddr *)&addr, &addrlen) < 0)
+	struct sockaddr *addr_base = (struct sockaddr *)&addr;
+	if (sio_getpeername(fd, addr_base, &addrlen) < 0)
 		luaL_error(L, "session.peer(): getpeername() failed");
 
-	lua_pushstring(L, sio_strfaddr((struct sockaddr *)&addr, addrlen));
+	char addrbuf[SERVICE_NAME_MAXLEN];
+	sio_addr_snprintf(addrbuf, sizeof(addrbuf), addr_base, addrlen);
+	lua_pushstring(L, addrbuf);
 	return 1;
 }
 
diff --git a/src/lib/core/sio.c b/src/lib/core/sio.c
index 25c34ea59..6d1732332 100644
--- a/src/lib/core/sio.c
+++ b/src/lib/core/sio.c
@@ -59,16 +59,17 @@ sio_socketname_to_buffer(int fd, char *buf, int size)
 		return 0;
 	struct sockaddr_storage addr;
 	socklen_t addrlen = sizeof(addr);
-	int rc = getsockname(fd, (struct sockaddr *) &addr, &addrlen);
+	struct sockaddr *base_addr = (struct sockaddr *)&addr;
+	int rc = getsockname(fd, base_addr, &addrlen);
 	if (rc == 0) {
-		SNPRINT(n, snprintf, buf, size, ", aka %s",
-			sio_strfaddr((struct sockaddr *)&addr, addrlen));
+		SNPRINT(n, snprintf, buf, size, ", aka ");
+		SNPRINT(n, sio_addr_snprintf, buf, size, base_addr, addrlen);
 	}
 	addrlen = sizeof(addr);
 	rc = getpeername(fd, (struct sockaddr *) &addr, &addrlen);
 	if (rc == 0) {
-		SNPRINT(n, snprintf, buf, size, ", peer of %s",
-			sio_strfaddr((struct sockaddr *)&addr, addrlen));
+		SNPRINT(n, snprintf, buf, size, ", peer of ");
+		SNPRINT(n, sio_addr_snprintf, buf, size, base_addr, addrlen);
 	}
 	return 0;
 }
@@ -326,26 +327,41 @@ sio_getsockname(int fd, struct sockaddr *addr, socklen_t *addrlen)
 	return 0;
 }
 
-const char *
-sio_strfaddr(const struct sockaddr *addr, socklen_t addrlen)
+int
+sio_addr_snprintf(char *buf, size_t size, const struct sockaddr *addr,
+		  socklen_t addrlen)
 {
+	int res;
 	if (addr->sa_family == AF_UNIX) {
 		struct sockaddr_un *u = (struct sockaddr_un *)addr;
 		if (addrlen >= sizeof(*u))
-			return tt_sprintf("unix/:%s", u->sun_path);
+			res = snprintf(buf, size, "unix/:%s", u->sun_path);
 		else
-			return tt_sprintf("unix/:(socket)");
+			res = snprintf(buf, size, "unix/:(socket)");
 	} else {
 		char host[NI_MAXHOST], serv[NI_MAXSERV];
 		int flags = NI_NUMERICHOST | NI_NUMERICSERV;
 		if (getnameinfo(addr, addrlen, host, sizeof(host), serv,
 				sizeof(serv), flags) != 0)
-			return tt_sprintf("(host):(port)");
+			res = snprintf(buf, size, "(host):(port)");
 		else if (addr->sa_family == AF_INET)
-			return tt_sprintf("%s:%s", host, serv);
+			res = snprintf(buf, size, "%s:%s", host, serv);
 		else
-			return tt_sprintf("[%s]:%s", host, serv);
+			res = snprintf(buf, size, "[%s]:%s", host, serv);
 	}
+	assert(res + 1 < SERVICE_NAME_MAXLEN);
+	assert(res >= 0);
+	return res;
+}
+
+const char *
+sio_strfaddr(const struct sockaddr *addr, socklen_t addrlen)
+{
+	int size = SERVICE_NAME_MAXLEN;
+	char *buf = (char *) static_reserve(size);
+	/* +1 for terminating 0. */
+	static_alloc(sio_addr_snprintf(buf, size, addr, addrlen) + 1);
+	return buf;
 }
 
 int
diff --git a/src/lib/core/sio.h b/src/lib/core/sio.h
index 4f5a7f6f3..016f1f079 100644
--- a/src/lib/core/sio.h
+++ b/src/lib/core/sio.h
@@ -73,6 +73,10 @@ sio_wouldblock(int err)
 	return err == EAGAIN || err == EWOULDBLOCK || err == EINTR;
 }
 
+/** Format the address into the given buffer. Behaves like snprintf(). */
+int
+sio_addr_snprintf(char *buf, size_t size, const struct sockaddr *addr,
+		  socklen_t addrlen);
 
 /**
  * Format the address provided in struct sockaddr *addr.
-- 
2.24.3 (Apple Git-128)