text_backend.cc
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1 /*
2  * Copyright (C) 1996-2025 The Squid Software Foundation and contributors
3  *
4  * Squid software is distributed under GPLv2+ license and includes
5  * contributions from numerous individuals and organizations.
6  * Please see the COPYING and CONTRIBUTORS files for details.
7  */
8 
9 /*
10  * AUTHOR: Robert Collins.
11  * Based on ncsa_auth.c by Arjan de Vet <Arjan.deVet@adv.iae.nl>
12  *
13  * Example digest auth text backend for Squid, based on the original
14  * proxy_auth code from client_side.c, written by
15  * Jon Thackray <jrmt@uk.gdscorp.com>.
16  *
17  * - comment lines are possible and should start with a '#';
18  * - empty or blank lines are possible;
19  * - file format is username:plaintext or username:realm:HA1
20  *
21  * To build a directory integrated backend, you need to be able to
22  * calculate the HA1 returned to squid. To avoid storing a plaintext
23  * password you can calculate MD5(username:realm:password) when the
24  * user changes their password, and store the tuple username:realm:HA1.
25  * then find the matching username:realm when squid asks for the
26  * HA1.
27  *
28  * This implementation could be improved by using such a triple for
29  * the file format. However storing such a triple does little to
30  * improve security: If compromised the username:realm:HA1 combination
31  * is "plaintext equivalent" - for the purposes of digest authentication
32  * they allow the user access. Password synchronization is not tackled
33  * by digest - just preventing on the wire compromise.
34  *
35  * Copyright (c) 2003 Robert Collins <robertc@squid-cache.org>
36  */
37 
38 #include "squid.h"
40 
41 static hash_table *hash = nullptr;
43 static char *passwdfile = nullptr;
44 static int ha1mode = 0;
45 static time_t change_time = 0;
46 
47 typedef struct _user_data {
49  char *passwd;
50  char *ha1;
51 } user_data;
52 
53 static void
54 my_free(void *p)
55 {
56  user_data *u = static_cast<user_data*>(p);
57  xfree(u->hash.key);
58  xfree(u->passwd);
59  xfree(u->ha1);
60  xfree(u);
61 }
62 
63 static void
64 read_passwd_file(const char *passwordFile, int isHa1Mode)
65 {
66  char buf[8192];
67  user_data *u;
68  char *user;
69  char *passwd;
70  char *ha1 = nullptr;
71  char *realm;
72 
73  if (hash != nullptr) {
76  hash = nullptr;
77  }
78  /* initial setup */
79  hash = hash_create((HASHCMP *) strcmp, 7921, hash_string);
80  if (nullptr == hash) {
81  fprintf(stderr, "digest_file_auth: cannot create hash table\n");
82  exit(EXIT_FAILURE);
83  }
84  FILE *f = fopen(passwordFile, "r");
85  if (!f) {
86  int xerrno = errno;
87  fprintf(stderr, "digest_file_auth: cannot open password file: %s\n", xstrerr(xerrno));
88  exit(EXIT_FAILURE);
89  }
90  unsigned int lineCount = 0;
91  while (fgets(buf, sizeof(buf), f) != nullptr) {
92  ha1 = nullptr;
93  ++lineCount;
94  if ((buf[0] == '#') || (buf[0] == ' ') || (buf[0] == '\t') ||
95  (buf[0] == '\n'))
96  continue;
97  user = strtok(buf, ":\n");
98  if (!user) {
99  fprintf(stderr, "digest_file_auth: missing user name at line %u in '%s'\n", lineCount, passwordFile);
100  continue;
101  }
102  realm = strtok(nullptr, ":\n");
103  passwd = strtok(nullptr, ":\n");
104  if (!passwd) {
105  passwd = realm;
106  realm = nullptr;
107  }
108  if ((strlen(user) > 0) && passwd) {
109  if (strncmp(passwd, "{HHA1}", 6) == 0) {
110  ha1 = passwd + 6;
111  passwd = nullptr;
112  } else if (isHa1Mode) {
113  ha1 = passwd;
114  passwd = nullptr;
115  }
116  if (ha1 && strlen(ha1) != 32) {
117  /* We cannot accept plaintext passwords when using HA1 encoding,
118  * as the passwords may be output to cache.log if debugging is on.
119  */
120  fprintf(stderr, "digest_file_auth: ignoring invalid password for %s\n", user);
121  continue;
122  }
123  u = static_cast<user_data*>(xcalloc(1, sizeof(*u)));
124  if (realm) {
125  int len = strlen(user) + strlen(realm) + 2;
126  u->hash.key = xmalloc(len);
127  snprintf(static_cast<char*>(u->hash.key), len, "%s:%s", user, realm);
128  } else {
129  u->hash.key = xstrdup(user);
130  }
131  if (ha1)
132  u->ha1 = xstrdup(ha1);
133  else
134  u->passwd = xstrdup(passwd);
135  hash_join(hash, &u->hash);
136  }
137  }
138  fclose(f);
139 }
140 
141 /* replace when changing the backend */
142 void
143 TextArguments(int argc, char **argv)
144 {
145  struct stat sb;
146  if (argc == 2)
147  passwdfile = argv[1];
148  if ((argc == 3) && !strcmp("-c", argv[1])) {
149  ha1mode = 1;
150  passwdfile = argv[2];
151  }
152  if (!passwdfile) {
153  fprintf(stderr, "Usage: digest_file_auth [OPTIONS] <passwordfile>\n");
154  fprintf(stderr, " -c accept digest hashed passwords rather than plaintext in passwordfile\n");
155  exit(EXIT_FAILURE);
156  }
157  if (stat(passwdfile, &sb) != 0) {
158  fprintf(stderr, "cannot stat %s\n", passwdfile);
159  exit(EXIT_FAILURE);
160  }
161 }
162 
163 static const user_data *
164 GetPassword(RequestData * requestData)
165 {
166  user_data *u;
167  struct stat sb;
168  char buf[256];
169  int len;
170  if (stat(passwdfile, &sb) == 0) {
171  if (sb.st_mtime != change_time) {
173  change_time = sb.st_mtime;
174  }
175  }
176  if (!hash)
177  return nullptr;
178  len = snprintf(buf, sizeof(buf), "%s:%s", requestData->user, requestData->realm);
179  if (len >= static_cast<int>(sizeof(buf)))
180  return nullptr;
181  u = (user_data*)hash_lookup(hash, buf);
182  if (u)
183  return u;
184  u = (user_data*)hash_lookup(hash, requestData->user);
185  return u;
186 }
187 
188 void
189 TextHHA1(RequestData * requestData)
190 {
191  const user_data *u = GetPassword(requestData);
192  if (!u) {
193  requestData->error = -1;
194  return;
195  }
196  if (u->ha1) {
197  xstrncpy(requestData->HHA1, u->ha1, sizeof(requestData->HHA1));
198  } else {
199  HASH HA1;
200  DigestCalcHA1("md5", requestData->user, requestData->realm, u->passwd, nullptr, nullptr, HA1, requestData->HHA1);
201  }
202 }
203 
const char * xstrerr(int error)
Definition: xstrerror.cc:83
void TextArguments(int argc, char **argv)
void * xcalloc(size_t n, size_t sz)
Definition: xalloc.cc:71
#define xmalloc
HASHHASH hash_string
Definition: hash.h:45
static int ha1mode
Definition: text_backend.cc:44
#define xstrdup
char * xstrncpy(char *dst, const char *src, size_t n)
Definition: xstring.cc:37
hash_link * hash_lookup(hash_table *, const void *)
Definition: hash.cc:146
int HASHCMP(const void *, const void *)
Definition: hash.h:13
void hashFreeMemory(hash_table *)
Definition: hash.cc:268
hash_link hash
Definition: text_backend.cc:48
void hashFreeItems(hash_table *, HASHFREE *)
Definition: hash.cc:252
void TextHHA1(RequestData *requestData)
char * ha1
Definition: text_backend.cc:50
static time_t change_time
Definition: text_backend.cc:45
static char * passwdfile
Definition: text_backend.cc:43
static hash_table * hash
Definition: text_backend.cc:41
static void read_passwd_file(const char *passwordFile, int isHa1Mode)
Definition: text_backend.cc:64
#define xfree
static HASHFREE my_free
Definition: text_backend.cc:42
void HASHFREE(void *)
Definition: hash.h:12
hash_table * hash_create(HASHCMP *, int, HASHHASH *)
Definition: hash.cc:108
char HASH[HASHLEN]
Definition: rfc2617.h:31
char * passwd
Definition: text_backend.cc:49
struct _user_data user_data
void DigestCalcHA1(const char *pszAlg, const char *pszUserName, const char *pszRealm, const char *pszPassword, const char *pszNonce, const char *pszCNonce, HASH HA1, HASHHEX SessionKey)
Definition: rfc2617.c:88
static const user_data * GetPassword(RequestData *requestData)
void hash_join(hash_table *, hash_link *)
Definition: hash.cc:131

 

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