C正则库做DNS域名验证时的性能对比
本文对C的正则库regex和pcre在做域名验证的场景下做评测。
验证DNS域名的正则表达式为:
"^[0-9a-zA-Z_-]+(\\.[0-9a-zA-Z_-]+)*(\\.[a-zA-Z]{2,}\\.)$"
对于正常DNS请求日志中的6177578条日志做正则验证处理。
1,pcre
评测所用的pcre的版本号是:7.8.3
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#include <stdio.h> #include <string.h> #include <pcre.h> #define OVECCOUNT 30 /* should be a multiple of 3 */ #define EBUFLEN 128 #define BUFLEN 1024 int main( int argc, char *argv[])
{ pcre *re;
const char *error;
int erroffset;
FILE *fd;
int ovector[OVECCOUNT];
int rc, i;
int succ = 0, fail = 0;
char src[1024];
char pattern[] = "^[0-9a-zA-Z_-]+(\\.[0-9a-zA-Z_-]+)*(\\.[a-zA-Z]{2,}\\.)$" ;
printf ( "Pattern: %s\n" , pattern);
re = pcre_compile(pattern, 0, &error, &erroffset, NULL);
if (re == NULL) {
printf ( "PCRE compilation failed at offset %d: %s\n" , erroffset, error);
return 1;
}
if ((fd = fopen (argv[1], "r" )) == NULL) {
printf ( "open file error\n" );
return 1;
}
while ( fgets (src, 1024, fd)) {
rc = pcre_exec(re, NULL, src, strlen (src), 0, 0, ovector, OVECCOUNT);
if (rc < 0) {
fail++;
} else {
succ++;
}
}
printf ( "success:%d fail:%d\n" , succ, fail);
fclose (fd);
free (re);
return 0;
} |
处理完所有数据的耗时是:
$time ./pcre_t query_domains
Pattern: ^[0-9a-zA-Z_-]+(\.[0-9a-zA-Z_-]+)*(\.[a-zA-Z]{2,}\.)$
success:6177443 fail:135
real 0m8.257s
user 0m8.194s
sys 0m0.058s
2,regex
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#include <stdio.h> #include <string.h> #include <regex.h> #define SUBSLEN 100 #define EBUFLEN 1280 #define BUFLEN 1024 int main( int argc, char *argv[])
{ size_t len;
regex_t re;
regmatch_t subs[SUBSLEN];
char matched[BUFLEN];
char errbuf[EBUFLEN];
int err, i, succ=0, fail=0;
FILE *fd;
char *src;
char line[1024];
char pattern[] = "^[0-9a-zA-Z_-]+(\\.[0-9a-zA-Z_-]+)*(\\.[a-zA-Z]+\\.)$" ;
printf ( "Pattern: %s\n" , pattern);
if (regcomp(&re, pattern, REG_EXTENDED | REG_NEWLINE)) {
len = regerror(err, &re, errbuf, sizeof (errbuf));
printf ( "error: regcomp: %s\n" , errbuf);
return 1;
}
if ((fd = fopen (argv[1], "r" )) == NULL) {
printf ( "open file error\n" );
return 1;
}
while ( fgets (line, 1024, fd)) {
err = regexec(&re, line, ( size_t ) SUBSLEN, subs, 0);
if (err == REG_NOMATCH) {
fail++;
} else {
succ++;
}
}
printf ( "success:%d, fails:%d\n" , succ, fail);
fclose (fd);
regfree(&re);
return (0);
} |
处理完所有数据耗时:
$time ./regex_t query_domains
Pattern: ^[0-9a-zA-Z_-]+(\.[0-9a-zA-Z_-]+)*(\.[a-zA-Z]+\.)$
success:6177443, fails:135
real 0m50.876s
user 0m50.783s
sys 0m0.058s
3,结论。
可以看到,对于域名验证的场景。pcre明显优于POSIX regex库。在规则已经编译好的情况下,pcre每秒大约处理74.8w条域名,而regex每秒大约处理12.1万条。