将OpenSSL链接到Webassembly
在问这个问题之前，我只想说我做了一些功课。这个问题与这里已经问过的非常相似 即 How to link OpenSSL with emscripten?
在我找到一本非常好的和详细的手册之后，如何在此处将OpenSSL编译为webassem https://www.ip6.li/node/129
我能够成功运行所有步骤，即
1）首先转到下载最新脚本的目录，然后设置一些路径变量：
~/emscripten/emsdk$ source ./emsdk_env.sh
2）然后执行上述手册中的脚本
./mk-openssl-webassemby.sh:
基本上，所有编译均无任何错误，但带有特定警告。编译后，我可以CD到crypto / sha目录，然后 看到文件被编译成所谓的中间表示形式：
/openssl/openssl-1.1.0h/openssl/crypto/sha$ file sha256.o
sha256.o: LLVM IR bitcode
在阅读其他在线资源时，我希望此文件具有.bc扩展名，但是.o似乎也是正确的。不确定。
我在编译过程中确实看到以下警告：
make[2]: Entering directory '/openssl/openssl-1.1.0h/openssl'
( :; LIBDEPS="${LIBDEPS:--L. -lssl -L. -lcrypto -lsocket -lnsl }"; LDCMD="${LDCMD:-emcc}"; LDFLAGS="${LDFLAGS:--DNDEBUG -DOPENSSL_NO_DYNAMIC_ENGINE -DOPENSSL_API_COMPAT=0x10100000L -DOPENSSLDIR="\"/tmp\"" -DENGINESDIR="\"/usr/local/lib/engines-1.1\"" -g -Wall }"; LIBPATH=`for x in $LIBDEPS; do echo $x; done | sed -e 's/^ *-L//;t' -e d | uniq`; LIBPATH=`echo $LIBPATH | sed -e 's/ /:/g'`; echo LD_LIBRARY_PATH=$LIBPATH:$LD_LIBRARY_PATH ${LDCMD} ${LDFLAGS} -o ${APPNAME:=test/buildtest_x509_vfy} test/buildtest_x509_vfy.o ${LIBDEPS}; LD_LIBRARY_PATH=$LIBPATH:$LD_LIBRARY_PATH ${LDCMD} ${LDFLAGS} -o ${APPNAME:=test/buildtest_x509_vfy} test/buildtest_x509_vfy.o ${LIBDEPS} )
LD_LIBRARY_PATH=.: emcc -DNDEBUG -DOPENSSL_NO_DYNAMIC_ENGINE -DOPENSSL_API_COMPAT=0x10100000L -DOPENSSLDIR="/tmp" -DENGINESDIR="/usr/local/lib/engines-1.1" -g -Wall -o test/buildtest_x509_vfy test/buildtest_x509_vfy.o -L. -lssl -L. -lcrypto -lsocket -lnsl
WARNING:root:emcc: cannot find library "socket"
WARNING:root:emcc: cannot find library "nsl"
基本上，它说我找不到库套接字和nsl。这里要提到的重要一点是编译完成没有错误，即仅是那些警告。如果我手动编辑Makefile并删除这些库并点击进行编译，则编译完成而没有任何警告。这意味着现在，无论代码之前存在任何外部库，现在都无法链接到某些x86或ARM体系结构，也就是说，所有这些都需要特定于wasm VM。
export CC=emcc
export CXX=emcc
export LINK=${CXX}
export ARCH_FLAGS=""
export ARCH_LINK=""
export CPPFLAGS=" ${ARCH_FLAGS} "
export CXXFLAGS=" ${ARCH_FLAGS} "
export CFLAGS=" ${ARCH_FLAGS} "
export LDFLAGS=" ${ARCH_LINK} "
echo $OSTYPE | grep -i darwin > /dev/null 2> /dev/null
./Configure purify --openssldir=/tmp --api=1.1.0 no-engine no-dso no-dgram no-sock no-srtp no-stdio no-ui no-err no-ocsp no-psk no-stdio no-ts
Configuring OpenSSL version 1.1.0h (0x1010008fL)
no-afalgeng [forced] OPENSSL_NO_AFALGENG
no-apps [forced] OPENSSL_NO_APPS
no-asan [default] OPENSSL_NO_ASAN
no-capieng [forced] OPENSSL_NO_CAPIENG
no-crypto-mdebug [default] OPENSSL_NO_CRYPTO_MDEBUG
no-crypto-mdebug-backtrace [default] OPENSSL_NO_CRYPTO_MDEBUG_BACKTRACE
no-dgram [option] OPENSSL_NO_DGRAM
no-dso [option]
no-dtls [forced] OPENSSL_NO_DTLS
no-dtls1 [forced] OPENSSL_NO_DTLS1
no-dtls1_2 [forced] OPENSSL_NO_DTLS1_2
no-dynamic-engine [forced]
no-ec_nistp_64_gcc_128 [default] OPENSSL_NO_EC_NISTP_64_GCC_128
no-egd [default] OPENSSL_NO_EGD
no-engine [option] OPENSSL_NO_ENGINE (skip engines)
no-err [option] OPENSSL_NO_ERR
no-fuzz-afl [default] OPENSSL_NO_FUZZ_AFL
no-fuzz-libfuzzer [default] OPENSSL_NO_FUZZ_LIBFUZZER
no-heartbeats [default] OPENSSL_NO_HEARTBEATS
no-md2 [default] OPENSSL_NO_MD2 (skip dir)
no-msan [default] OPENSSL_NO_MSAN
no-ocsp [option] OPENSSL_NO_OCSP (skip dir)
no-psk [option] OPENSSL_NO_PSK
no-rc5 [default] OPENSSL_NO_RC5 (skip dir)
no-sctp [default] OPENSSL_NO_SCTP
no-sock [option] OPENSSL_NO_SOCK
no-srtp [option] OPENSSL_NO_SRTP
no-ssl-trace [default] OPENSSL_NO_SSL_TRACE
no-ssl3 [default] OPENSSL_NO_SSL3
no-ssl3-method [default] OPENSSL_NO_SSL3_METHOD
no-stdio [option] OPENSSL_NO_STDIO
no-tests [forced] OPENSSL_NO_TESTS
no-ts [option] OPENSSL_NO_TS (skip dir)
no-ubsan [default] OPENSSL_NO_UBSAN
no-ui [option] OPENSSL_NO_UI (skip dir)
no-unit-test [default] OPENSSL_NO_UNIT_TEST
no-weak-ssl-ciphers [default] OPENSSL_NO_WEAK_SSL_CIPHERS
no-zlib [default]
no-zlib-dynamic [default]
Configuring for purify
CC =emcc
CFLAG =-g -Wall
SHARED_CFLAG =
DEFINES =NDEBUG OPENSSL_NO_DYNAMIC_ENGINE OPENSSL_API_COMPAT=0x10100000L
LFLAG =
PLIB_LFLAG =
EX_LIBS = -lsocket -lnsl
APPS_OBJ =
CPUID_OBJ =mem_clr.o
UPLINK_OBJ =
BN_ASM =bn_asm.o
EC_ASM =
DES_ENC =des_enc.o fcrypt_b.o
AES_ENC =aes_core.o aes_cbc.o
BF_ENC =bf_enc.o
CAST_ENC =c_enc.o
RC4_ENC =rc4_enc.o rc4_skey.o
RC5_ENC =rc5_enc.o
MD5_OBJ_ASM =
SHA1_OBJ_ASM =
RMD160_OBJ_ASM=
CMLL_ENC =camellia.o cmll_misc.o cmll_cbc.o
MODES_OBJ =
PADLOCK_OBJ =
CHACHA_ENC =chacha_enc.o
POLY1305_OBJ =
BLAKE2_OBJ =
PROCESSOR =
RANLIB =ranlib
ARFLAGS =
PERL =/usr/bin/perl
THIRTY_TWO_BIT mode
Configured for purify.
The library could not be configured for supporting multi-threaded
applications as the compiler options required on this system are not known.
See file INSTALL for details if you need multi-threading.
The options 'shared', 'pic' and 'dynamic-engine' aren't supported on this
the platform, so we will pretend you gave the option 'no-pic', which also disables
'shared' and 'dynamic-engine'. If you know how to implement shared libraries
or independent position code, please let us know (but please first make sure
you have tried with a current version of OpenSSL).
在编译OpenSSL之后，我确实在目录中看到以下文件
libcrypto.a
libcrypto.pc
libssl.a
libssl.pc
如果我测试看看文件的含义，即看到这是我需要链接到的档案
file libcrypto.a
libcrypto.a: current ar archive
如果我测试看看符号是否在那里
llvm-nm libcrypto.a
sham_sha1.o:
U EVP_MD_CTX_md_data
-------- T EVP_sha1
-------- T EVP_sha224
-------- T EVP_sha256
-------- T EVP_sha384
-------- T EVP_sha512
U OPENSSL_cleanse
U SHA1_Final
U SHA1_Init
U SHA1_Update
U SHA224_Final
U SHA224_Init
U SHA224_Update
U SHA256_Final
U SHA256_Init
U SHA256_Update
U SHA384_Final
U SHA384_Init
U SHA384_Update
U SHA512_Final
U SHA512_Init
U SHA512_Update
-------- t ctrl
-------- t final
-------- t final224
-------- t final256
-------- t final384
-------- t final512
-------- t init
-------- t init224
-------- t init256
-------- t init384
-------- t init512
-------- d sha1_md
-------- d sha224_md
-------- d sha256_md
-------- d sha384_md
-------- d sha512_md
-------- t update
-------- t update224
-------- t update256
-------- t update384
-------- t update512
...
sha256.o:
...
-------- d K256
U OPENSSL_cleanse
-------- T SHA224
-------- d SHA224.m
-------- T SHA224_Final
-------- T SHA224_Init
-------- T SHA224_Update
-------- T SHA256
-------- d SHA256.m
-------- T SHA256_Final
-------- T SHA256_Init
-------- T SHA256_Transform
-------- T SHA256_Update
-------- t sha256_block_data_order
-------- d sha256_block_data_order.is_endian
...
llvm-nm libcrypto.a |grep -i SHA256_Update
U SHA256_Update
-------- T SHA256_Update
3）当我尝试在cmake中链接到该问题时，即开始出现问题。
warning: unresolved symbol: SHA256_Final
warning: unresolved symbol: SHA256_Init
warning: unresolved symbol: SHA256_Update
或具有详细输出：
VERBOSE is on, this generates a lot of output and can slow down compilation
warning: unresolved symbol: SHA256_Final
adding _SHA256_Final and deps : function _SHA256_Final() {
err('missing
warning: unresolved symbol: SHA256_Init
adding _SHA256_Init and deps : function _SHA256_Init() {
err('missing f
warning: unresolved symbol: SHA256_Update
adding _SHA256_Update and deps : function _SHA256_Update() {
err('missing
adding ___buildEnvironment and deps $ENV : function ___buildEnvironment(environ) {
有趣的是，Web程序集已加载，并且我能够执行不依赖于OpenSSL的方法，但是当我尝试执行某些OpenSSL方法时，我在Firefox控制台中收到以下错误：
missing function: SHA256_Init
在我的CmakeLists.txt中，我有两个使用的目录。
set( OPENSSL_INCLUDE_DIR /openssl/openssl-1.1.0h/openssl/include )
set( OPENSSL_LINK_DIR /openssl/openssl-1.1.0h/openssl )
并且我的目标命令看起来像
set_target_properties(mainTest PROPERTIES LINK_FLAGS " -s WASM=1 -s NO_EXIT_RUNTIME=1 -s VERBOSE=1 -lssl -lcrypto --pre-js preModule.js")
它建立了wasm，但是我不能使用那些方法。我想知道为什么我会遇到那些“未解决的符号”冲突。任何帮助深表感谢。
答案 0 :(得分：1)
解决方案非常简单。我忘记将以下内容添加到cmake文件中
target_link_libraries（mainTest加密货币） 在那之后一切都没有警告。