From 8c9750fb30e5829dccd0a0453bb8a8efaba67b33 Mon Sep 17 00:00:00 2001 From: ahgamut <41098605+ahgamut@users.noreply.github.com> Date: Sat, 3 Jul 2021 19:51:43 +0530 Subject: [PATCH] implement getservbyname and getservbyport getservbyname and getservbyport have implementation similar to that of gethostbyname and gethostbyaddr. However, there is no struct ServicesTxt like struct HostsTxt. For every call of getservbyname/getservbyport the lookup of /etc/services is done by opening the file and parsing each line one-by-one. This is slow, but the implementation is simple, and the file parsing is similar to ParseHostsTxt. --- libc/dns/ent.h | 2 +- libc/dns/getservbyname.c | 32 ++++++- libc/dns/getservbyport.c | 31 ++++++- libc/dns/servicestxt.c | 190 +++++++++++++++++++++++++++++++++++++++ libc/dns/servicestxt.h | 17 ++++ 5 files changed, 269 insertions(+), 3 deletions(-) create mode 100644 libc/dns/servicestxt.c create mode 100644 libc/dns/servicestxt.h diff --git a/libc/dns/ent.h b/libc/dns/ent.h index 20fc8f9e9..b37ab46fe 100644 --- a/libc/dns/ent.h +++ b/libc/dns/ent.h @@ -19,7 +19,7 @@ struct hostent { struct servent { char *s_name; /* official service name */ char **s_aliases; /* alias list */ - int s_port; /* port number */ + int s_port; /* port number (in network byte order) */ char *s_proto; /* protocol to use */ }; diff --git a/libc/dns/getservbyname.c b/libc/dns/getservbyname.c index 050b8aabb..39e6d0484 100644 --- a/libc/dns/getservbyname.c +++ b/libc/dns/getservbyname.c @@ -26,7 +26,37 @@ │ │ ╚─────────────────────────────────────────────────────────────────────────────*/ #include "libc/dns/ent.h" +#include "libc/dns/servicestxt.h" +#include "libc/mem/mem.h" struct servent *getservbyname(const char *name, const char *proto) { - return NULL; + static struct servent *ptr0, se0; + char *localproto = proto; + int p; + + if (!ptr0) { + se0.s_name = NULL; + se0.s_aliases = (char **)malloc(sizeof(char *) * 1); + if (!se0.s_aliases) return NULL; + se0.s_aliases[0] = NULL; + + se0.s_port = 0; + se0.s_proto = NULL; + ptr0 = &se0; + } + + p = LookupServicesByName(name, &localproto); + if (p == -1) return NULL; + + ptr0->s_port = p; + if (ptr0->s_name) free(ptr0->s_name); + ptr0->s_name = strdup(name); + + if (ptr0->s_proto) free(ptr0->s_proto); + ptr0->s_proto = strdup(localproto); + + // localproto got alloc'd during the lookup + if (!proto && localproto != proto) free(localproto); + + return ptr0; } diff --git a/libc/dns/getservbyport.c b/libc/dns/getservbyport.c index 52cad8bd6..d80a56418 100644 --- a/libc/dns/getservbyport.c +++ b/libc/dns/getservbyport.c @@ -26,7 +26,36 @@ │ │ ╚─────────────────────────────────────────────────────────────────────────────*/ #include "libc/dns/ent.h" +#include "libc/dns/servicestxt.h" struct servent *getservbyport(int port, const char *proto) { - return NULL; + static struct servent *ptr1, se1; + char name[DNS_NAME_MAX]; + char *localproto = proto; + + if (!ptr1) { + se1.s_name = NULL; + se1.s_aliases = (char **)malloc(sizeof(char *) * 1); + if (!se1.s_aliases) return NULL; + se1.s_aliases[0] = NULL; + + se1.s_port = 0; + se1.s_proto = NULL; + ptr1 = &se1; + } + + if (LookupServicesByPort(port, &localproto, name, sizeof(name)) == -1) + return NULL; + + ptr1->s_port = port; + if (ptr1->s_name) free(ptr1->s_name); + ptr1->s_name = strdup(name); + + if (ptr1->s_proto) free(ptr1->s_proto); + ptr1->s_proto = strdup(localproto); + + // localproto got alloc'd during the lookup + if (!proto && localproto != proto) free(localproto); + + return ptr1; } diff --git a/libc/dns/servicestxt.c b/libc/dns/servicestxt.c new file mode 100644 index 000000000..0d4e25f9e --- /dev/null +++ b/libc/dns/servicestxt.c @@ -0,0 +1,190 @@ +/*-*- 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/dns/servicestxt.h" + +#include "libc/bits/safemacros.internal.h" +#include "libc/dce.h" +#include "libc/errno.h" +#include "libc/fmt/conv.h" +#include "libc/fmt/fmt.h" +#include "libc/macros.internal.h" +#include "libc/mem/mem.h" +#include "libc/nt/systeminfo.h" +#include "libc/runtime/runtime.h" +#include "libc/str/str.h" + +static textwindows noinline char *GetNtServicesTxtPath(char *pathbuf, + uint32_t size) { + const char *const kWinHostsPath = "\\drivers\\etc\\services"; + uint32_t len = GetSystemDirectoryA(&pathbuf[0], size); + if (len && len + strlen(kWinHostsPath) + 1 < size) { + if (pathbuf[len] == '\\') pathbuf[len--] = '\0'; + memcpy(&pathbuf[len], kWinHostsPath, strlen(kWinHostsPath) + 1); + return &pathbuf[0]; + } else { + return NULL; + } +} + +/** + * Opens and searches /etc/services to find name for a given port. + * + * format of /etc/services is like this: + * + * # comment + * # NAME PORT/PROTOCOL ALIASES + * + * ftp 21/tcp + * fsp 21/udp fspd + * ssh 22/tcp + * + * @param servport is the port number (in network byte order) + * @param servproto is a pointer to a string (*servproto can be NULL) + * @param buf is a buffer to store the resulting name + * @param bufsize is the size of buf + * @returns 0 on success, -1 on error + * + * @note aliases are not read from the file. + */ +int LookupServicesByPort(const int servport, char **servproto, char *buf, + size_t bufsize) { + FILE *f; + char *line; + char pathbuf[512]; + const char *path; + size_t linesize; + int count, found; + char *name, *port, *proto, *comment, *tok; + + path = "/etc/services"; + if (IsWindows()) { + path = firstnonnull(GetNtServicesTxtPath(pathbuf, ARRAYLEN(pathbuf)), path); + } + if (bufsize == 0 || !(f = fopen(path, "r"))) { + return -1; + } + line = NULL; + linesize = 0; + count = 0; + found = 0; + + while (found == 0 && (getline(&line, &linesize, f)) != -1) { + if ((comment = strchr(line, '#'))) *comment = '\0'; + name = strtok_r(line, " \t\r\n\v", &tok); + port = strtok_r(NULL, "/ \t\r\n\v", &tok); + if (name && port && servport == htons(atoi(port))) { + if (!(proto = strtok_r(NULL, " \t\r\n\v", &tok))) + continue; + else if (!servproto[0]) { + servproto[0] = strdup(proto); + strncpy(buf, name, bufsize); + found = 1; + } else if (strcmp(proto, servproto[0]) == 0) { + strncpy(buf, name, bufsize); + found = 1; + } + } + count++; + } + free(line); + + if (ferror(f)) { + errno = ferror(f); + return -1; + } + fclose(f); + + if (!found) return -1; + + return 0; +} + +/** + * Opens and searches /etc/services to find port for a given name. + * + * @param servname is a NULL-terminated string + * @param servproto is a pointer to a string (*servproto can be NULL) + * @returns -1 on error, or + * positive port number (in network byte order) + * + * @note aliases are not read from the file. + * @see LookupServicesByPort + */ +int LookupServicesByName(const char *servname, char **servproto) { + FILE *f; + char *line; + char pathbuf[512]; + const char *path; + size_t linesize; + int count, found, result; + char *name, *port, *proto, *comment, *tok; + + path = "/etc/services"; + + if (IsWindows()) { + path = firstnonnull(GetNtServicesTxtPath(pathbuf, ARRAYLEN(pathbuf)), path); + } + if (!(f = fopen(path, "r"))) { + return -1; + } + line = NULL; + linesize = 0; + count = 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); + port = strtok_r(NULL, "/ \t\r\n\v", &tok); + if (name && port && strcmp(name, servname) == 0) { + if (!(proto = strtok_r(NULL, " \t\r\n\v", &tok))) + continue; + else if (!servproto[0]) { + servproto[0] = strdup(proto); + result = htons(atoi(port)); + found = 1; + } else if (strcmp(proto, servproto[0]) == 0) { + result = htons(atoi(port)); + found = 1; + } + } + count++; + } + free(line); + + if (ferror(f)) { + errno = ferror(f); + return -1; + } + fclose(f); + + if (!found) return -1; + + return result; +} diff --git a/libc/dns/servicestxt.h b/libc/dns/servicestxt.h new file mode 100644 index 000000000..4b9cbfb41 --- /dev/null +++ b/libc/dns/servicestxt.h @@ -0,0 +1,17 @@ +#ifndef COSMOPOLITAN_LIBC_DNS_SERVICESTXT_H_ +#define COSMOPOLITAN_LIBC_DNS_SERVICESTXT_H_ +#include "libc/sock/sock.h" +#include "libc/stdio/stdio.h" + +#if !(__ASSEMBLER__ + __LINKER__ + 0) +COSMOPOLITAN_C_START_ + +int LookupServicesByPort(const int, char **, char *, size_t) + paramsnonnull((2, 3)); +int LookupServicesByName(const char *, char **) paramsnonnull((1, 2)); + +/* TODO: implement like struct HostsTxt? */ + +COSMOPOLITAN_C_END_ +#endif /* !(__ASSEMBLER__ + __LINKER__ + 0) */ +#endif /* COSMOPOLITAN_LIBC_DNS_SERVICESTXT_H_ */