Mainline doesn't build

[a1exeyk]

make all fails with error (-Werror)

cc -pedantic -Wall -Werror -Wimplicit -Wunused -Wcomment -Wchar-subscripts -Wuninitialized -Wshadow -Wcast-qual -Wcast-align -Wwrite-strings -Wstack-protector -fPIC -std=c99 -D_POSIX_C_SOURCE=200112L -fstack-protector-all -O2 -I../libcrypto-root/include/ -I../api/ -I../ -Wno-deprecated-declarations -Wno-unknown-pragmas -Wformat-security -D_FORTIFY_SOURCE=2   -c -o s2n_server_extensions.o s2n_server_extensions.c
cc1: warnings being treated as errors
s2n_server_extensions.c: In function ‘s2n_server_recv_alpn’:
s2n_server_extensions.c:116: warning: comparison is always false due to limited range of data type

Compiler is valid as uint8_t is compared with size_t:

if (protocol_len > sizeof(conn->application_protocol) - 1) {

My system and compiler are pretty outdated. So feel free to close if that's not an issue with modern gcc.

$ uname -sp
Linux x86_64
$ gcc --version
gcc (GCC) 4.1.2 20080704 (Red Hat 4.1.2-54)
Copyright (C) 2006 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

[a1exeyk]

With the following definition of char application_protocol[256]; at tls/s2n_connection.h:130 sizeof(conn->application_protocol) - 1 evaluates to 255 and protocol_len > 255 is always false. So the check is pointless with the current version of code. However it still seems useful if definition of application_protocol ever changes.

[a1exeyk]

This does not reproduce on gcc 4.6 as it supports -Wtype-limits warning category disabled by default which can not be disabled on gcc 4.1.2 .

Also s2n doesn't make use of -Wextra warnings.

[colmmacc]

This should now be fixed as of 5479e97

[a1exeyk]

Although removed check is a noop with the current code. It is useful for two reasons:

• reader doesn't have to worry whether protocol_len has correct range or check is missed by mistake
• it guards against future changes of application_protocol[]

The if check was correct, warning was wrong.