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| author | schwarze <> | 2016-11-05 15:32:20 +0000 |
|---|---|---|
| committer | schwarze <> | 2016-11-05 15:32:20 +0000 |
| commit | b3e8c428c609fc9c66690abb3d188c60b5d48bb1 (patch) | |
| tree | 1672f1234352c29443fcacb44e22f1b20f174d99 /src/lib/libssl/doc/SSL_read.3 | |
| parent | 19bc742a20d4c505bc890d49e01c44192e9dbeff (diff) | |
| download | openbsd-b3e8c428c609fc9c66690abb3d188c60b5d48bb1.tar.gz openbsd-b3e8c428c609fc9c66690abb3d188c60b5d48bb1.tar.bz2 openbsd-b3e8c428c609fc9c66690abb3d188c60b5d48bb1.zip | |
move manual pages from doc/ to man/ for consistency with other
libraries, in particular considering that there are unrelated
files in doc/; requested by jsing@ and beck@
Diffstat (limited to 'src/lib/libssl/doc/SSL_read.3')
| -rw-r--r-- | src/lib/libssl/doc/SSL_read.3 | 193 |
1 files changed, 0 insertions, 193 deletions
diff --git a/src/lib/libssl/doc/SSL_read.3 b/src/lib/libssl/doc/SSL_read.3 deleted file mode 100644 index d6e5960958..0000000000 --- a/src/lib/libssl/doc/SSL_read.3 +++ /dev/null | |||
| @@ -1,193 +0,0 @@ | |||
| 1 | .\" | ||
| 2 | .\" $OpenBSD: SSL_read.3,v 1.2 2014/12/02 14:11:01 jmc Exp $ | ||
| 3 | .\" | ||
| 4 | .Dd $Mdocdate: December 2 2014 $ | ||
| 5 | .Dt SSL_READ 3 | ||
| 6 | .Os | ||
| 7 | .Sh NAME | ||
| 8 | .Nm SSL_read | ||
| 9 | .Nd read bytes from a TLS/SSL connection | ||
| 10 | .Sh SYNOPSIS | ||
| 11 | .In openssl/ssl.h | ||
| 12 | .Ft int | ||
| 13 | .Fn SSL_read "SSL *ssl" "void *buf" "int num" | ||
| 14 | .Sh DESCRIPTION | ||
| 15 | .Fn SSL_read | ||
| 16 | tries to read | ||
| 17 | .Fa num | ||
| 18 | bytes from the specified | ||
| 19 | .Fa ssl | ||
| 20 | into the buffer | ||
| 21 | .Fa buf . | ||
| 22 | .Sh NOTES | ||
| 23 | If necessary, | ||
| 24 | .Fn SSL_read | ||
| 25 | will negotiate a TLS/SSL session, if not already explicitly performed by | ||
| 26 | .Xr SSL_connect 3 | ||
| 27 | or | ||
| 28 | .Xr SSL_accept 3 . | ||
| 29 | If the peer requests a re-negotiation, | ||
| 30 | it will be performed transparently during the | ||
| 31 | .Fn SSL_read | ||
| 32 | operation. | ||
| 33 | The behaviour of | ||
| 34 | .Fn SSL_read | ||
| 35 | depends on the underlying | ||
| 36 | .Vt BIO . | ||
| 37 | .Pp | ||
| 38 | For the transparent negotiation to succeed, the | ||
| 39 | .Fa ssl | ||
| 40 | must have been initialized to client or server mode. | ||
| 41 | This is being done by calling | ||
| 42 | .Xr SSL_set_connect_state 3 | ||
| 43 | or | ||
| 44 | .Xr SSL_set_accept_state 3 | ||
| 45 | before the first call to | ||
| 46 | .Fn SSL_read | ||
| 47 | or | ||
| 48 | .Xr SSL_write 3 . | ||
| 49 | .Pp | ||
| 50 | .Fn SSL_read | ||
| 51 | works based on the SSL/TLS records. | ||
| 52 | The data are received in records (with a maximum record size of 16kB for | ||
| 53 | SSLv3/TLSv1). | ||
| 54 | Only after a record has been completely received can it be processed | ||
| 55 | (decrypted and checked for integrity). | ||
| 56 | Therefore data not retrieved at the last call of | ||
| 57 | .Fn SSL_read | ||
| 58 | can still be buffered inside the SSL layer and will be retrieved on the next | ||
| 59 | call to | ||
| 60 | .Fn SSL_read . | ||
| 61 | If | ||
| 62 | .Fa num | ||
| 63 | is higher than the number of bytes buffered, | ||
| 64 | .Fn SSL_read | ||
| 65 | will return with the bytes buffered. | ||
| 66 | If no more bytes are in the buffer, | ||
| 67 | .Fn SSL_read | ||
| 68 | will trigger the processing of the next record. | ||
| 69 | Only when the record has been received and processed completely will | ||
| 70 | .Fn SSL_read | ||
| 71 | return reporting success. | ||
| 72 | At most the contents of the record will be returned. | ||
| 73 | As the size of an SSL/TLS record may exceed the maximum packet size of the | ||
| 74 | underlying transport (e.g., TCP), it may be necessary to read several packets | ||
| 75 | from the transport layer before the record is complete and | ||
| 76 | .Fn SSL_read | ||
| 77 | can succeed. | ||
| 78 | .Pp | ||
| 79 | If the underlying | ||
| 80 | .Vt BIO | ||
| 81 | is | ||
| 82 | .Em blocking , | ||
| 83 | .Fn SSL_read | ||
| 84 | will only return once the read operation has been finished or an error | ||
| 85 | has occurred, except when a renegotiation take place, in which case a | ||
| 86 | .Dv SSL_ERROR_WANT_READ | ||
| 87 | may occur. | ||
| 88 | This behavior can be controlled with the | ||
| 89 | .Dv SSL_MODE_AUTO_RETRY | ||
| 90 | flag of the | ||
| 91 | .Xr SSL_CTX_set_mode 3 | ||
| 92 | call. | ||
| 93 | .Pp | ||
| 94 | If the underlying | ||
| 95 | .Vt BIO | ||
| 96 | is | ||
| 97 | .Em non-blocking , | ||
| 98 | .Fn SSL_read | ||
| 99 | will also return when the underlying | ||
| 100 | .Vt BIO | ||
| 101 | could not satisfy the needs of | ||
| 102 | .Fn SSL_read | ||
| 103 | to continue the operation. | ||
| 104 | In this case a call to | ||
| 105 | .Xr SSL_get_error 3 | ||
| 106 | with the return value of | ||
| 107 | .Fn SSL_read | ||
| 108 | will yield | ||
| 109 | .Dv SSL_ERROR_WANT_READ | ||
| 110 | or | ||
| 111 | .Dv SSL_ERROR_WANT_WRITE . | ||
| 112 | As at any time a re-negotiation is possible, a call to | ||
| 113 | .Fn SSL_read | ||
| 114 | can also cause write operations! | ||
| 115 | The calling process then must repeat the call after taking appropriate action | ||
| 116 | to satisfy the needs of | ||
| 117 | .Fn SSL_read . | ||
| 118 | The action depends on the underlying | ||
| 119 | .Vt BIO . | ||
| 120 | When using a non-blocking socket, nothing is to be done, but | ||
| 121 | .Xr select 2 | ||
| 122 | can be used to check for the required condition. | ||
| 123 | When using a buffering | ||
| 124 | .Vt BIO , | ||
| 125 | like a | ||
| 126 | .Vt BIO | ||
| 127 | pair, data must be written into or retrieved out of the | ||
| 128 | .Vt BIO | ||
| 129 | before being able to continue. | ||
| 130 | .Pp | ||
| 131 | .Xr SSL_pending 3 | ||
| 132 | can be used to find out whether there are buffered bytes available for | ||
| 133 | immediate retrieval. | ||
| 134 | In this case | ||
| 135 | .Fn SSL_read | ||
| 136 | can be called without blocking or actually receiving new data from the | ||
| 137 | underlying socket. | ||
| 138 | .Sh WARNING | ||
| 139 | When an | ||
| 140 | .Fn SSL_read | ||
| 141 | operation has to be repeated because of | ||
| 142 | .Dv SSL_ERROR_WANT_READ | ||
| 143 | or | ||
| 144 | .Dv SSL_ERROR_WANT_WRITE , | ||
| 145 | it must be repeated with the same arguments. | ||
| 146 | .Sh RETURN VALUES | ||
| 147 | The following return values can occur: | ||
| 148 | .Bl -tag -width Ds | ||
| 149 | .It >0 | ||
| 150 | The read operation was successful; the return value is the number of bytes | ||
| 151 | actually read from the TLS/SSL connection. | ||
| 152 | .It 0 | ||
| 153 | The read operation was not successful. | ||
| 154 | The reason may either be a clean shutdown due to a | ||
| 155 | .Dq close notify | ||
| 156 | alert sent by the peer (in which case the | ||
| 157 | .Dv SSL_RECEIVED_SHUTDOWN | ||
| 158 | flag in the ssl shutdown state is set (see | ||
| 159 | .Xr SSL_shutdown 3 | ||
| 160 | and | ||
| 161 | .Xr SSL_set_shutdown 3 ) . | ||
| 162 | It is also possible that the peer simply shut down the underlying transport and | ||
| 163 | the shutdown is incomplete. | ||
| 164 | Call | ||
| 165 | .Fn SSL_get_error | ||
| 166 | with the return value to find out whether an error occurred or the connection | ||
| 167 | was shut down cleanly | ||
| 168 | .Pq Dv SSL_ERROR_ZERO_RETURN . | ||
| 169 | .Pp | ||
| 170 | SSLv2 (deprecated) does not support a shutdown alert protocol, so it can only | ||
| 171 | be detected whether the underlying connection was closed. | ||
| 172 | It cannot be checked whether the closure was initiated by the peer or by | ||
| 173 | something else. | ||
| 174 | .It <0 | ||
| 175 | The read operation was not successful, because either an error occurred or | ||
| 176 | action must be taken by the calling process. | ||
| 177 | Call | ||
| 178 | .Fn SSL_get_error | ||
| 179 | with the return value to find out the reason. | ||
| 180 | .El | ||
| 181 | .Sh SEE ALSO | ||
| 182 | .Xr bio 3 , | ||
| 183 | .Xr ssl 3 , | ||
| 184 | .Xr SSL_accept 3 , | ||
| 185 | .Xr SSL_connect 3 , | ||
| 186 | .Xr SSL_CTX_new 3 , | ||
| 187 | .Xr SSL_CTX_set_mode 3 , | ||
| 188 | .Xr SSL_get_error 3 , | ||
| 189 | .Xr SSL_pending 3 , | ||
| 190 | .Xr SSL_set_connect_state 3 , | ||
| 191 | .Xr SSL_set_shutdown 3 , | ||
| 192 | .Xr SSL_shutdown 3 , | ||
| 193 | .Xr SSL_write 3 | ||
