Need to know which gcc switches I miss to compile a C script

Question

I try to validate a x509 signature from a c script, but I can't figure out what I miss to compile it successfully.

I use Ubuntu 13.10, xmlsec1 1.2.18 (openssl), libxml2 2.9.1.

What I tried :

gcc -I/usr/include/xmlsec1 -I/usr/include/libxml2 -o xmlsec-verify-with-X509 xmlsec-verify-with-X509.c 

But I get :

In file included from xmlsec-verify-with-X509.c:39:0:
/usr/include/xmlsec1/xmlsec/crypto.h:59:2: error: #error No crypto library defined
 #error No crypto library defined
  ^

The crypto.h file until line 59 :

#ifdef XMLSEC_CRYPTO_DYNAMIC_LOADING
#include <xmlsec/app.h>
#else /* XMLSEC_CRYPTO_DYNAMIC_LOADING */
#ifdef XMLSEC_CRYPTO_OPENSSL
#include <xmlsec/openssl/app.h>
#include <xmlsec/openssl/crypto.h>
#include <xmlsec/openssl/x509.h>
#include <xmlsec/openssl/symbols.h>
#else /* XMLSEC_CRYPTO_OPENSSL */
#ifdef XMLSEC_CRYPTO_MSCRYPTO
#include <xmlsec/mscrypto/app.h>
#include <xmlsec/mscrypto/crypto.h>
#include <xmlsec/mscrypto/x509.h>
#include <xmlsec/mscrypto/symbols.h>
#else /* XMLSEC_CRYPTO_MSCRYPTO */
#ifdef XMLSEC_CRYPTO_NSS
#include <xmlsec/nss/app.h>
#include <xmlsec/nss/crypto.h>
#include <xmlsec/openssl/x509.h>
#include <xmlsec/nss/symbols.h>
#else /* XMLSEC_CRYPTO_NSS */
#ifdef XMLSEC_CRYPTO_GNUTLS
#include <xmlsec/gnutls/app.h>
#include <xmlsec/gnutls/crypto.h>
#include <xmlsec/gnutls/symbols.h>
#else /* XMLSEC_CRYPTO_GNUTLS */
#ifdef XMLSEC_CRYPTO_GCRYPT
#include <xmlsec/gcrypt/app.h>
#include <xmlsec/gcrypt/crypto.h>
#include <xmlsec/gcrypt/symbols.h>
#else /* XMLSEC_CRYPTO_GCRYPT */
#error No crypto library defined

The script comes from http://www.aleksey.com/xmlsec/api/xmlsec-verify-with-x509.html :

#include <stdlib.h>
#include <string.h>
#include <assert.h>

#include <libxml/tree.h>
#include <libxml/xmlmemory.h>
#include <libxml/parser.h>

#ifndef XMLSEC_NO_XSLT
#include <libxslt/xslt.h>
#include <libxslt/security.h>
#endif /* XMLSEC_NO_XSLT */

#include <xmlsec/xmlsec.h>
#include <xmlsec/xmltree.h>
#include <xmlsec/xmldsig.h>
#include <xmlsec/crypto.h>

xmlSecKeysMngrPtr load_trusted_certs(char** files, int files_size);
int verify_file(xmlSecKeysMngrPtr mngr, const char* xml_file);

int 
main(int argc, char **argv) {
#ifndef XMLSEC_NO_XSLT
    xsltSecurityPrefsPtr xsltSecPrefs = NULL;
#endif /* XMLSEC_NO_XSLT */
    xmlSecKeysMngrPtr mngr;

    assert(argv);

    if(argc < 3) {
        fprintf(stderr, "Error: wrong number of arguments.\n");
        fprintf(stderr, "Usage: %s <xml-file> <cert-file1> [<cert-file2> [...]]\n", argv[0]);
        return(1);
    }

    /* Init libxml and libxslt libraries */
    xmlInitParser();
    LIBXML_TEST_VERSION
    xmlLoadExtDtdDefaultValue = XML_DETECT_IDS | XML_COMPLETE_ATTRS;
    xmlSubstituteEntitiesDefault(1);
#ifndef XMLSEC_NO_XSLT
    xmlIndentTreeOutput = 1; 
#endif /* XMLSEC_NO_XSLT */

    /* Init libxslt */
#ifndef XMLSEC_NO_XSLT
    /* disable everything */
    xsltSecPrefs = xsltNewSecurityPrefs(); 
    xsltSetSecurityPrefs(xsltSecPrefs,  XSLT_SECPREF_READ_FILE,        xsltSecurityForbid);
    xsltSetSecurityPrefs(xsltSecPrefs,  XSLT_SECPREF_WRITE_FILE,       xsltSecurityForbid);
    xsltSetSecurityPrefs(xsltSecPrefs,  XSLT_SECPREF_CREATE_DIRECTORY, xsltSecurityForbid);
    xsltSetSecurityPrefs(xsltSecPrefs,  XSLT_SECPREF_READ_NETWORK,     xsltSecurityForbid);
    xsltSetSecurityPrefs(xsltSecPrefs,  XSLT_SECPREF_WRITE_NETWORK,    xsltSecurityForbid);
    xsltSetDefaultSecurityPrefs(xsltSecPrefs); 
#endif /* XMLSEC_NO_XSLT */

    /* Init xmlsec library */
    if(xmlSecInit() < 0) {
        fprintf(stderr, "Error: xmlsec initialization failed.\n");
        return(-1);
    }

    /* Check loaded library version */
    if(xmlSecCheckVersion() != 1) {
        fprintf(stderr, "Error: loaded xmlsec library version is not compatible.\n");
        return(-1);
    }

    /* Load default crypto engine if we are supporting dynamic
     * loading for xmlsec-crypto libraries. Use the crypto library
     * name ("openssl", "nss", etc.) to load corresponding 
     * xmlsec-crypto library.
     */
#ifdef XMLSEC_CRYPTO_DYNAMIC_LOADING
    if(xmlSecCryptoDLLoadLibrary(BAD_CAST XMLSEC_CRYPTO) < 0) {
        fprintf(stderr, "Error: unable to load default xmlsec-crypto library. Make sure\n"
                        "that you have it installed and check shared libraries path\n"
                        "(LD_LIBRARY_PATH) envornment variable.\n");
        return(-1);     
    }
#endif /* XMLSEC_CRYPTO_DYNAMIC_LOADING */

    /* Init crypto library */
    if(xmlSecCryptoAppInit(NULL) < 0) {
        fprintf(stderr, "Error: crypto initialization failed.\n");
        return(-1);
    }

    /* Init xmlsec-crypto library */
    if(xmlSecCryptoInit() < 0) {
        fprintf(stderr, "Error: xmlsec-crypto initialization failed.\n");
        return(-1);
    }

    /* create keys manager and load trusted certificates */
    mngr = load_trusted_certs(&(argv[2]), argc - 2);
    if(mngr == NULL) {
        return(-1);
    }

    /* verify file */
    if(verify_file(mngr, argv[1]) < 0) {
        xmlSecKeysMngrDestroy(mngr);    
        return(-1);
    }    

    /* destroy keys manager */
    xmlSecKeysMngrDestroy(mngr);

    /* Shutdown xmlsec-crypto library */
    xmlSecCryptoShutdown();

    /* Shutdown crypto library */
    xmlSecCryptoAppShutdown();

    /* Shutdown xmlsec library */
    xmlSecShutdown();

    /* Shutdown libxslt/libxml */
#ifndef XMLSEC_NO_XSLT
    xsltFreeSecurityPrefs(xsltSecPrefs);
    xsltCleanupGlobals();            
#endif /* XMLSEC_NO_XSLT */
    xmlCleanupParser();

    return(0);
}

/**
 * load_trusted_certs:
 * @files:              the list of filenames.
 * @files_size:         the number of filenames in #files.
 *
 * Creates simple keys manager and load trusted certificates from PEM #files.
 * The caller is responsible for destroing returned keys manager using
 * @xmlSecKeysMngrDestroy.
 *
 * Returns the pointer to newly created keys manager or NULL if an error
 * occurs.
 */
xmlSecKeysMngrPtr 
load_trusted_certs(char** files, int files_size) {
    xmlSecKeysMngrPtr mngr;
    int i;

    assert(files);
    assert(files_size > 0);

    /* create and initialize keys manager, we use a simple list based
     * keys manager, implement your own xmlSecKeysStore klass if you need
     * something more sophisticated 
     */
    mngr = xmlSecKeysMngrCreate();
    if(mngr == NULL) {
        fprintf(stderr, "Error: failed to create keys manager.\n");
        return(NULL);
    }
    if(xmlSecCryptoAppDefaultKeysMngrInit(mngr) < 0) {
        fprintf(stderr, "Error: failed to initialize keys manager.\n");
        xmlSecKeysMngrDestroy(mngr);
        return(NULL);
    }    

    for(i = 0; i < files_size; ++i) {
        assert(files[i]);

        /* load trusted cert */
        if(xmlSecCryptoAppKeysMngrCertLoad(mngr, files[i], xmlSecKeyDataFormatPem, xmlSecKeyDataTypeTrusted) < 0) {
            fprintf(stderr,"Error: failed to load pem certificate from \"%s\"\n", files[i]);
            xmlSecKeysMngrDestroy(mngr);
            return(NULL);
        }
    }

    return(mngr);
}

/** 
 * verify_file:
 * @mngr:               the pointer to keys manager.
 * @xml_file:           the signed XML file name.
 *
 * Verifies XML signature in #xml_file.
 *
 * Returns 0 on success or a negative value if an error occurs.
 */
int 
verify_file(xmlSecKeysMngrPtr mngr, const char* xml_file) {
    xmlDocPtr doc = NULL;
    xmlNodePtr node = NULL;
    xmlSecDSigCtxPtr dsigCtx = NULL;
    int res = -1;

    assert(mngr);
    assert(xml_file);

    /* load file */
    doc = xmlParseFile(xml_file);
    if ((doc == NULL) || (xmlDocGetRootElement(doc) == NULL)){
        fprintf(stderr, "Error: unable to parse file \"%s\"\n", xml_file);
        goto done;      
    }

    /* find start node */
    node = xmlSecFindNode(xmlDocGetRootElement(doc), xmlSecNodeSignature, xmlSecDSigNs);
    if(node == NULL) {
        fprintf(stderr, "Error: start node not found in \"%s\"\n", xml_file);
        goto done;      
    }

    /* create signature context */
    dsigCtx = xmlSecDSigCtxCreate(mngr);
    if(dsigCtx == NULL) {
        fprintf(stderr,"Error: failed to create signature context\n");
        goto done;
    }

    /* Verify signature */
    if(xmlSecDSigCtxVerify(dsigCtx, node) < 0) {
        fprintf(stderr,"Error: signature verify\n");
        goto done;
    }

    /* print verification result to stdout */
    if(dsigCtx->status == xmlSecDSigStatusSucceeded) {
        fprintf(stdout, "Signature is OK\n");
    } else {
        fprintf(stdout, "Signature is INVALID\n");
    }    

    /* success */
    res = 0;

done:    
    /* cleanup */
    if(dsigCtx != NULL) {
        xmlSecDSigCtxDestroy(dsigCtx);
    }

    if(doc != NULL) {
        xmlFreeDoc(doc); 
    }
    return(res);
}

Edit1 :

If I try with -DXMLSEC_CRYPTO_OPENSSL

$ gcc -DXMLSEC_CRYPTO_OPENSSL -I/usr/include/xmlsec1 -I/usr/include/libxml2 -o xmlsec-verify-with-X509 xmlsec-verify-with-X509.c 
/tmp/ccBwmeSC.o: In function `main':
xmlsec-verify-with-X509.c:(.text+0x86): undefined reference to `xmlInitParser'
xmlsec-verify-with-X509.c:(.text+0x90): undefined reference to `xmlCheckVersion'
xmlsec-verify-with-X509.c:(.text+0x95): undefined reference to `__xmlLoadExtDtdDefaultValue'
xmlsec-verify-with-X509.c:(.text+0xa5): undefined reference to `xmlSubstituteEntitiesDefault'
xmlsec-verify-with-X509.c:(.text+0xaa): undefined reference to `__xmlIndentTreeOutput'
xmlsec-verify-with-X509.c:(.text+0xb5): undefined reference to `xsltNewSecurityPrefs'
xmlsec-verify-with-X509.c:(.text+0xc2): undefined reference to `xsltSecurityForbid'
xmlsec-verify-with-X509.c:(.text+0xcf): undefined reference to `xsltSetSecurityPrefs'
xmlsec-verify-with-X509.c:(.text+0xd8): undefined reference to `xsltSecurityForbid'
xmlsec-verify-with-X509.c:(.text+0xe5): undefined reference to `xsltSetSecurityPrefs'
xmlsec-verify-with-X509.c:(.text+0xee): undefined reference to `xsltSecurityForbid'
xmlsec-verify-with-X509.c:(.text+0xfb): undefined reference to `xsltSetSecurityPrefs'
xmlsec-verify-with-X509.c:(.text+0x104): undefined reference to `xsltSecurityForbid'
xmlsec-verify-with-X509.c:(.text+0x111): undefined reference to `xsltSetSecurityPrefs'
xmlsec-verify-with-X509.c:(.text+0x11a): undefined reference to `xsltSecurityForbid'
xmlsec-verify-with-X509.c:(.text+0x127): undefined reference to `xsltSetSecurityPrefs'
xmlsec-verify-with-X509.c:(.text+0x133): undefined reference to `xsltSetDefaultSecurityPrefs'
xmlsec-verify-with-X509.c:(.text+0x138): undefined reference to `xmlSecInit'
xmlsec-verify-with-X509.c:(.text+0x17d): undefined reference to `xmlSecCheckVersionExt'
xmlsec-verify-with-X509.c:(.text+0x1b4): undefined reference to `xmlSecOpenSSLAppInit'
xmlsec-verify-with-X509.c:(.text+0x1e5): undefined reference to `xmlSecOpenSSLInit'
xmlsec-verify-with-X509.c:(.text+0x265): undefined reference to `xmlSecKeysMngrDestroy'
xmlsec-verify-with-X509.c:(.text+0x278): undefined reference to `xmlSecKeysMngrDestroy'
xmlsec-verify-with-X509.c:(.text+0x27d): undefined reference to `xmlSecOpenSSLShutdown'
xmlsec-verify-with-X509.c:(.text+0x282): undefined reference to `xmlSecOpenSSLAppShutdown'
xmlsec-verify-with-X509.c:(.text+0x287): undefined reference to `xmlSecShutdown'
xmlsec-verify-with-X509.c:(.text+0x293): undefined reference to `xsltFreeSecurityPrefs'
xmlsec-verify-with-X509.c:(.text+0x298): undefined reference to `xsltCleanupGlobals'
xmlsec-verify-with-X509.c:(.text+0x29d): undefined reference to `xmlCleanupParser'
/tmp/ccBwmeSC.o: In function `load_trusted_certs':
xmlsec-verify-with-X509.c:(.text+0x2f7): undefined reference to `xmlSecKeysMngrCreate'
xmlsec-verify-with-X509.c:(.text+0x336): undefined reference to `xmlSecOpenSSLAppDefaultKeysMngrInit'
xmlsec-verify-with-X509.c:(.text+0x364): undefined reference to `xmlSecKeysMngrDestroy'
xmlsec-verify-with-X509.c:(.text+0x3dc): undefined reference to `xmlSecOpenSSLAppKeysMngrCertLoad'
xmlsec-verify-with-X509.c:(.text+0x41c): undefined reference to `xmlSecKeysMngrDestroy'
/tmp/ccBwmeSC.o: In function `verify_file':
xmlsec-verify-with-X509.c:(.text+0x4b4): undefined reference to `xmlParseFile'
xmlsec-verify-with-X509.c:(.text+0x4cb): undefined reference to `xmlDocGetRootElement'
xmlsec-verify-with-X509.c:(.text+0x4fe): undefined reference to `xmlDocGetRootElement'
xmlsec-verify-with-X509.c:(.text+0x503): undefined reference to `xmlSecDSigNs'
xmlsec-verify-with-X509.c:(.text+0x508): undefined reference to `xmlSecNodeSignature'
xmlsec-verify-with-X509.c:(.text+0x510): undefined reference to `xmlSecFindNode'
xmlsec-verify-with-X509.c:(.text+0x549): undefined reference to `xmlSecDSigCtxCreate'
xmlsec-verify-with-X509.c:(.text+0x58a): undefined reference to `xmlSecDSigCtxVerify'
xmlsec-verify-with-X509.c:(.text+0x615): undefined reference to `xmlSecDSigCtxDestroy'
xmlsec-verify-with-X509.c:(.text+0x628): undefined reference to `xmlFreeDoc'
collect2: error: ld returned 1 exit status

With -DXMLSEC_CRYPTO_DYNAMIC_LOADING

$ gcc -DXMLSEC_CRYPTO_DYNAMIC_LOADING  -I/usr/include/xmlsec1 -I/usr/include/libxml2 -o xmlsec-verify-with-X509 xmlsec-verify-with-X509.c 
xmlsec-verify-with-X509.c: In function 'main':
xmlsec-verify-with-X509.c:76:43: error: 'XMLSEC_CRYPTO' undeclared (first use in this function)
     if(xmlSecCryptoDLLoadLibrary(BAD_CAST XMLSEC_CRYPTO) < 0) {
                                           ^
xmlsec-verify-with-X509.c:76:43: note: each undeclared identifier is reported only once for each function it appears in

Answer 1

Like alk said in the comments (thanks for your help), there's a page on xmlsec project to explain how to build some Makefile with xmlsec, so finally I get it to work with this Makefile :

PROGRAM = xmlsec-verify-with-X509
PROGRAM_FILES = xmlsec-verify-with-X509.c

CFLAGS  += -g $(shell xmlsec1-config --cflags)
LDFLAGS += -g
LIBS    += $(shell xmlsec1-config --libs)

all: $(PROGRAM)

%: %.c
    $(cc) $(PROGRAM_FILES) $(CFLAGS) $(LDFLAGS) -o $(PROGRAM) $(LIBS)

clean:
    @rm -rf $(PROGRAM)

Then :

cc=gcc make