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authorAllan McRae <allan@archlinux.org>2012-11-02 23:06:45 +1000
committerAllan McRae <allan@archlinux.org>2013-02-09 12:43:37 +1000
commit05745089ac7009e5de84d676dd0823acd8c4d1fc (patch)
tree41e6102648ddc45627700e9396050910883336b9
parent4ec6848f91ed85ab113185bb74b83a5faf21160f (diff)
Add function to extract key id from signatures
This does not support all possibilities of RFC4880, but it does cover every key currently used in Arch Linux. Signed-off-by: Allan McRae <allan@archlinux.org>
-rw-r--r--lib/libalpm/signing.c113
-rw-r--r--lib/libalpm/signing.h3
2 files changed, 116 insertions, 0 deletions
diff --git a/lib/libalpm/signing.c b/lib/libalpm/signing.c
index 6534fe51..dc882821 100644
--- a/lib/libalpm/signing.c
+++ b/lib/libalpm/signing.c
@@ -950,4 +950,117 @@ int SYMEXPORT alpm_siglist_cleanup(alpm_siglist_t *siglist)
return 0;
}
+/**
+ * Extract the Issuer Key ID from a signature
+ * @param sig PGP signature
+ * @param len length of signature
+ * @param keys a pointer to storage for key IDs
+ * @return 0 on success, -1 on error
+ */
+int _alpm_extract_keyid(alpm_handle_t *handle, const char *identifier,
+ const unsigned char *sig, const size_t len, alpm_list_t **keys)
+{
+ size_t pos, spos, blen, hlen, ulen, slen;
+ pos = 0;
+
+ while(pos < len) {
+ if(!(sig[pos] & 0x80)) {
+ _alpm_log(handle, ALPM_LOG_ERROR,
+ _("%s: signature format error"), identifier);
+ return -1;
+ }
+
+ if(sig[pos] & 0x40) {
+ /* "new" packet format is not supported */
+ _alpm_log(handle, ALPM_LOG_ERROR,
+ _("%s: unsupported signature format"), identifier);
+ return -1;
+ }
+
+ if(((sig[pos] & 0x3f) >> 2) != 2) {
+ /* signature is not a "Signature Packet" */
+ _alpm_log(handle, ALPM_LOG_ERROR,
+ _("%s: signature format error"), identifier);
+ return -1;
+ }
+
+ switch(sig[pos] & 0x03) {
+ case 0:
+ blen = sig[pos + 1];
+ pos = pos + 2;
+ break;
+
+ case 1:
+ blen = (sig[pos + 1] << 8) | sig[pos + 2];
+ pos = pos + 3;
+ break;
+
+ case 2:
+ blen = (sig[pos + 1] << 24) | (sig[pos + 2] << 16) | (sig[pos + 3] << 8) | sig[pos + 4];
+ pos = pos + 5;
+ break;
+
+ case 3:
+ /* partial body length not supported */
+ _alpm_log(handle, ALPM_LOG_ERROR,
+ _("%s: unsupported signature format"), identifier);
+ return -1;
+ }
+
+ if(sig[pos] != 4) {
+ /* only support version 4 signature packet format */
+ _alpm_log(handle, ALPM_LOG_ERROR,
+ _("%s: unsupported signature format"), identifier);
+ return -1;
+ }
+
+ if(sig[pos + 1] != 0x00) {
+ /* not a signature of a binary document */
+ _alpm_log(handle, ALPM_LOG_ERROR,
+ _("%s: signature format error"), identifier);
+ return -1;
+ }
+
+ pos = pos + 4;
+
+ hlen = (sig[pos] << 8) | sig[pos + 1];
+ pos = pos + hlen + 2;
+
+ ulen = (sig[pos] << 8) | sig[pos + 1];
+ pos = pos + 2;
+
+ spos = pos;
+
+ while(spos < pos + ulen) {
+ if(sig[spos] < 192) {
+ slen = sig[spos];
+ spos = spos + 1;
+ } else if(sig[spos] < 255) {
+ slen = (sig[spos] << 8) | sig[spos + 1];
+ spos = spos + 2;
+ } else {
+ slen = (sig[spos + 1] << 24) | (sig[spos + 2] << 16) | (sig[spos + 3] << 8) | sig[spos + 4];
+ spos = spos + 5;
+ }
+
+ if(sig[spos] == 16) {
+ /* issuer key ID */
+ char key[17];
+ size_t i;
+ for (i = 0; i < 8; i++) {
+ sprintf(&key[i * 2], "%02X", sig[spos + i + 1]);
+ }
+ *keys = alpm_list_add(*keys, strdup(key));
+ break;
+ }
+
+ spos = spos + slen;
+ }
+
+ pos = pos + (blen - hlen - 8);
+ }
+
+ return 0;
+}
+
/* vim: set ts=2 sw=2 noet: */
diff --git a/lib/libalpm/signing.h b/lib/libalpm/signing.h
index 42b60b1f..ce9edcdc 100644
--- a/lib/libalpm/signing.h
+++ b/lib/libalpm/signing.h
@@ -34,6 +34,9 @@ int _alpm_process_siglist(alpm_handle_t *handle, const char *identifier,
int _alpm_key_in_keychain(alpm_handle_t *handle, const char *fpr);
int _alpm_key_import(alpm_handle_t *handle, const char *fpr);
+int _alpm_extract_keyid(alpm_handle_t *handle, const char *identifier,
+ const unsigned char *sig, const size_t len, alpm_list_t **keys);
+
#endif /* _ALPM_SIGNING_H */
/* vim: set ts=2 sw=2 noet: */