cosmopolitan/libc/dns/lookupprotobyname.c
Justine Tunney 2046c0d2ae Make improvements
- Expand redbean UNIX module
- Expand redbean documentation
- Ensure Lua copyright is embedded in binary
- Increase the PATH_MAX limit especially on NT
- Use column major sorting for linenoise completions
- Fix some suboptimalities in redbean's new UNIX API
- Figured out right flags for Multics newline in raw mode
2022-04-24 10:06:05 -07:00

98 lines
4.4 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ This is free and unencumbered software released into the public domain. │
│ │
│ Anyone is free to copy, modify, publish, use, compile, sell, or │
│ distribute this software, either in source code form or as a compiled │
│ binary, for any purpose, commercial or non-commercial, and by any │
│ means. │
│ │
│ In jurisdictions that recognize copyright laws, the author or authors │
│ of this software dedicate any and all copyright interest in the │
│ software to the public domain. We make this dedication for the benefit │
│ of the public at large and to the detriment of our heirs and │
│ successors. We intend this dedication to be an overt act of │
│ relinquishment in perpetuity of all present and future rights to this │
│ software under copyright law. │
│ │
│ THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, │
│ EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF │
│ MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. │
│ IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR │
│ OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, │
│ ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR │
│ OTHER DEALINGS IN THE SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/bits/safemacros.internal.h"
#include "libc/dns/prototxt.h"
#include "libc/errno.h"
#include "libc/fmt/conv.h"
#include "libc/macros.internal.h"
/**
* Opens and searches /etc/protocols to find number for a given name.
*
* @param protoname is a NULL-terminated string
* @param buf is a buffer to store the official name of the protocol
* @param bufsize is the size of buf
* @param filepath is the location of protocols file
* (if NULL, uses /etc/protocols)
* @return -1 on error, or
* positive protocol number
*
* @note aliases are read from file for comparison, but not returned.
* @see LookupProtoByNumber
*/
int LookupProtoByName(const char *protoname, char *buf, size_t bufsize,
const char *filepath) {
FILE *f;
char *line;
const char *path;
size_t linesize;
int found, result;
char pathbuf[PATH_MAX + 1];
char *name, *number, *alias, *comment, *tok;
if (!(path = filepath)) {
path = "/etc/protocols";
if (IsWindows()) {
path =
firstnonnull(GetNtProtocolsTxtPath(pathbuf, ARRAYLEN(pathbuf)), path);
}
}
if (bufsize == 0 || !(f = fopen(path, "r"))) {
return -1;
}
line = NULL;
linesize = 0;
found = 0;
result = -1;
while (found == 0 && (getline(&line, &linesize, f)) != -1) {
if ((comment = strchr(line, '#'))) *comment = '\0';
name = strtok_r(line, " \t\r\n\v", &tok);
number = strtok_r(NULL, "/ \t\r\n\v", &tok);
if (name && number) {
alias = name;
while (alias && strcasecmp(alias, protoname) != 0)
alias = strtok_r(NULL, " \t\r\n\v", &tok);
if (alias) /* alias matched with protoname */
{
if (!memccpy(buf, name, '\0', bufsize)) {
strcpy(buf, "");
break;
}
result = atoi(number);
found = 1;
}
}
}
free(line);
if (ferror(f)) {
errno = ferror(f);
return -1;
}
fclose(f);
if (!found) return -1;
return result;
}