1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
|
#include "cache.h"
#include "tag.h"
#include "exec_cmd.h"
/*
* A signature file has a very simple fixed format: four lines
* of "object <sha1>" + "type <typename>" + "tag <tagname>" +
* "tagger <committer>", followed by a blank line, a free-form tag
* message and a signature block that git itself doesn't care about,
* but that can be verified with gpg or similar.
*
* The first four lines are guaranteed to be at least 83 bytes:
* "object <sha1>\n" is 48 bytes, "type tag\n" at 9 bytes is the
* shortest possible type-line, "tag .\n" at 6 bytes is the shortest
* single-character-tag line, and "tagger . <> 0 +0000\n" at 20 bytes is
* the shortest possible tagger-line.
*/
/*
* We refuse to tag something we can't verify. Just because.
*/
static int verify_object(const unsigned char *sha1, const char *expected_type)
{
int ret = -1;
enum object_type type;
unsigned long size;
const unsigned char *repl;
void *buffer = read_sha1_file_repl(sha1, &type, &size, &repl);
if (buffer) {
if (type == type_from_string(expected_type))
ret = check_sha1_signature(repl, buffer, size, expected_type);
free(buffer);
}
return ret;
}
#ifdef NO_C99_FORMAT
#define PD_FMT "%d"
#else
#define PD_FMT "%td"
#endif
static int verify_tag(char *buffer, unsigned long size)
{
int typelen;
char type[20];
unsigned char sha1[20];
const char *object, *type_line, *tag_line, *tagger_line, *lb, *rb;
size_t len;
if (size < 84)
return error("wanna fool me ? you obviously got the size wrong !");
buffer[size] = 0;
/* Verify object line */
object = buffer;
if (memcmp(object, "object ", 7))
return error("char%d: does not start with \"object \"", 0);
if (get_sha1_hex(object + 7, sha1))
return error("char%d: could not get SHA1 hash", 7);
/* Verify type line */
type_line = object + 48;
if (memcmp(type_line - 1, "\ntype ", 6))
return error("char%d: could not find \"\\ntype \"", 47);
/* Verify tag-line */
tag_line = strchr(type_line, '\n');
if (!tag_line)
return error("char" PD_FMT ": could not find next \"\\n\"", type_line - buffer);
tag_line++;
if (memcmp(tag_line, "tag ", 4) || tag_line[4] == '\n')
return error("char" PD_FMT ": no \"tag \" found", tag_line - buffer);
/* Get the actual type */
typelen = tag_line - type_line - strlen("type \n");
if (typelen >= sizeof(type))
return error("char" PD_FMT ": type too long", type_line+5 - buffer);
memcpy(type, type_line+5, typelen);
type[typelen] = 0;
/* Verify that the object matches */
if (verify_object(sha1, type))
return error("char%d: could not verify object %s", 7, sha1_to_hex(sha1));
/* Verify the tag-name: we don't allow control characters or spaces in it */
tag_line += 4;
for (;;) {
unsigned char c = *tag_line++;
if (c == '\n')
break;
if (c > ' ')
continue;
return error("char" PD_FMT ": could not verify tag name", tag_line - buffer);
}
/* Verify the tagger line */
tagger_line = tag_line;
if (memcmp(tagger_line, "tagger ", 7))
return error("char" PD_FMT ": could not find \"tagger \"",
tagger_line - buffer);
/*
* Check for correct form for name and email
* i.e. " <" followed by "> " on _this_ line
* No angle brackets within the name or email address fields.
* No spaces within the email address field.
*/
tagger_line += 7;
if (!(lb = strstr(tagger_line, " <")) || !(rb = strstr(lb+2, "> ")) ||
strpbrk(tagger_line, "<>\n") != lb+1 ||
strpbrk(lb+2, "><\n ") != rb)
return error("char" PD_FMT ": malformed tagger field",
tagger_line - buffer);
/* Check for author name, at least one character, space is acceptable */
if (lb == tagger_line)
return error("char" PD_FMT ": missing tagger name",
tagger_line - buffer);
/* timestamp, 1 or more digits followed by space */
tagger_line = rb + 2;
if (!(len = strspn(tagger_line, "0123456789")))
return error("char" PD_FMT ": missing tag timestamp",
tagger_line - buffer);
tagger_line += len;
if (*tagger_line != ' ')
return error("char" PD_FMT ": malformed tag timestamp",
tagger_line - buffer);
tagger_line++;
/* timezone, 5 digits [+-]hhmm, max. 1400 */
if (!((tagger_line[0] == '+' || tagger_line[0] == '-') &&
strspn(tagger_line+1, "0123456789") == 4 &&
tagger_line[5] == '\n' && atoi(tagger_line+1) <= 1400))
return error("char" PD_FMT ": malformed tag timezone",
tagger_line - buffer);
tagger_line += 6;
/* Verify the blank line separating the header from the body */
if (*tagger_line != '\n')
return error("char" PD_FMT ": trailing garbage in tag header",
tagger_line - buffer);
/* The actual stuff afterwards we don't care about.. */
return 0;
}
#undef PD_FMT
int main(int argc, char **argv)
{
struct strbuf buf = STRBUF_INIT;
unsigned char result_sha1[20];
if (argc != 1)
usage("git mktag < signaturefile");
git_extract_argv0_path(argv[0]);
setup_git_directory();
if (strbuf_read(&buf, 0, 4096) < 0) {
die_errno("could not read from stdin");
}
/* Verify it for some basic sanity: it needs to start with
"object <sha1>\ntype\ntagger " */
if (verify_tag(buf.buf, buf.len) < 0)
die("invalid tag signature file");
if (write_sha1_file(buf.buf, buf.len, tag_type, result_sha1) < 0)
die("unable to write tag file");
strbuf_release(&buf);
printf("%s\n", sha1_to_hex(result_sha1));
return 0;
}
|
