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1 #include "msg_proto.h" |
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2 |
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3 #include <string.h> |
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4 #include <stdint.h> |
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5 #include <arpa/inet.h> |
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6 |
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7 /** |
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8 * I/O buffer |
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9 */ |
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10 struct msg_buf { |
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11 /** Buffer base pointer */ |
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12 char *base; |
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13 |
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14 /** Size of the buffer */ |
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15 size_t size; |
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16 |
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17 /** Current read/write offset */ |
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18 size_t off; |
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19 }; |
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20 |
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21 /** |
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22 * The minimum size used for any msg_buf::size related operation. |
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23 */ |
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24 #define MSG_BUF_MIN_SIZE 1024 |
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25 |
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26 /** |
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27 * Growth rate for size |
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28 */ |
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29 #define MSG_BUF_GROW_RATE 2 |
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30 |
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31 /** |
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32 * Initialize a message buffer at the given initial size |
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33 */ |
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34 err_t msg_buf_init (struct msg_buf *buf, size_t hint) |
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35 { |
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36 // apply minimum size |
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37 if (hint < MSG_BUF_MIN_SIZE) |
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38 hint = MSG_BUF_MIN_SIZE; |
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39 |
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40 // allocate the initial buffer |
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41 if ((buf->base = malloc(hint)) == NULL) |
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42 return ERR_MEM; |
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43 |
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44 // set fields |
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45 buf->size = hint; |
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46 buf->off = 0; |
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47 |
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48 // ok |
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49 return SUCCESS; |
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50 } |
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51 |
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52 /** |
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53 * Grow the buffer if needed to fit the given capacity. |
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54 */ |
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55 err_t msg_buf_grow (struct msg_buf *buf, size_t size) |
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56 { |
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57 char *tmp = buf->base; |
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58 |
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59 if (buf->size >= size) |
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60 // nothing to do |
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61 return SUCCESS; |
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62 |
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63 // calculate new size |
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64 while (buf->size < size) |
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65 buf->size *= MSG_BUF_GROW_RATE; |
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66 |
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67 // resize |
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68 if ((buf->base = realloc(buf->base, buf->size)) == NULL) { |
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69 buf->base = tmp; |
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70 |
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71 return ERR_MEM; |
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72 } |
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73 |
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74 // ok |
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75 return SUCCESS; |
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76 } |
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77 |
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78 /** |
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79 * Drain \a len bytes off the head of the buffer |
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80 */ |
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81 err_t msg_buf_drain (struct msg_buf *buf, size_t len) |
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82 { |
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83 // simple memmove |
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84 memmove(buf->base, buf->base + len, buf->off - len); |
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85 |
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86 // update offfset |
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87 buf->off -= len; |
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88 |
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89 // ok |
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90 return SUCCESS; |
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91 } |
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92 |
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93 /** |
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94 * Read into the buffer from a transport_t. |
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95 * |
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96 * This will attempt to read \a len bytes onto the end of the buffer, growing it if needed to fit. |
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97 * |
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98 * This may read/return more data than the given len. Use msg_buf_drain the remove the data from the buffer once you |
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99 * have used it. |
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100 * |
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101 * Returns the number of new bytes read, zero for transport read buffer empty, -err_t for error. |
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102 */ |
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103 ssize_t msg_buf_read (struct msg_buf *buf, transport_t *transport, size_t len, error_t *err) |
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104 { |
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105 ssize_t ret; |
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106 |
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107 // clamp size |
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108 if (len < MSG_BUF_MIN_SIZE) |
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109 len = MSG_BUF_MIN_SIZE; |
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110 |
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111 // ensure space |
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112 if ((ERROR_CODE(err) = msg_buf_grow(buf, buf->off + len))) |
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113 goto error; |
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114 |
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115 // read |
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116 if ((ret = transport_read(transport, buf->base + buf->off, len, err)) < 0) |
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117 goto error; |
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118 |
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119 // no data left? |
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120 if (!ret) |
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121 return 0; |
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122 |
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123 // update offset |
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124 buf->off += ret; |
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125 |
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126 // ok |
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127 return ret; |
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128 |
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129 error: |
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130 return -ERROR_CODE(err); |
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131 } |
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132 |
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133 /** |
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134 * Drives transport_write on the given data until all the given data is written, or zero is returned. |
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135 * |
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136 * @param transport transport to write to |
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137 * @param data input data |
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138 * @param len number of bytes to write from data |
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139 * @param err returned error info |
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140 * @return number of bytes written (which may be zero or less than len), or -err_t. |
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141 */ |
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142 static ssize_t _transport_write_all (transport_t *transport, const char *data, size_t len, error_t *err) |
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143 { |
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144 ssize_t ret; |
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145 size_t written = 0; |
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146 |
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147 while (len) { |
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148 // try and write out remaining data |
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149 if ((ret = transport_write(transport, data, len, err)) < 0) |
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150 goto error; |
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151 |
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152 if (!ret) { |
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153 // write buffer full |
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154 break; |
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155 |
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156 } else { |
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157 // update and continue |
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158 written += ret; |
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159 data += ret; |
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160 len -= ret; |
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161 } |
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162 } |
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163 |
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164 // ok |
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165 return written; |
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166 |
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167 error: |
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168 return -ERROR_CODE(err); |
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169 } |
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170 |
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171 /** |
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172 * If the buffer is empty, this will attempt to write the given data directly using transport_write until either all |
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173 * the data is written (in which case nothing more needs to be done), or the transport won't accept any more writes, |
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174 * in which case the remaining data will be buffered. |
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175 * |
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176 * If the buffer is not empty, then the given data will be added to the end of the buffer, since otherwise the order of |
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177 * data would be broken. |
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178 * |
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179 * In either case, transport_write semantics garuntee that our buffer will either be empty, or an on_write will be |
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180 * pending on the transport. See msg_buf_flush() for how to handle transport_callbacks::on_write. |
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181 */ |
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182 err_t msg_buf_write (struct msg_buf *buf, transport_t *transport, const void *data_ptr, size_t len, error_t *err) |
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183 { |
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184 ssize_t ret; |
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185 const char *data = data_ptr; |
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186 |
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187 if (!buf->off) { |
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188 // no data buffered, so we can try and write directly |
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189 if ((ret = _transport_write_all(transport, data, len, err)) < 0) |
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190 goto error; |
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191 |
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192 // update written |
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193 data += ret; |
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194 len -= ret; |
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195 |
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196 if (len == 0) |
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197 // wrote it all |
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198 return SUCCESS; |
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199 } |
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200 |
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201 // ensure space |
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202 if ((ERROR_CODE(err) = msg_buf_grow(buf, buf->off + len))) |
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203 goto error; |
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204 |
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205 // store |
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206 memcpy(buf->base + buf->off, data, len); |
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207 |
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208 // update |
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209 buf->off += len; |
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210 |
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211 // ok |
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212 return SUCCESS; |
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213 |
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214 error: |
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215 return ERROR_CODE(err); |
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216 } |
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217 |
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218 /** |
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219 * Flush buffered write data to the transport, driving transport_write() until either all of our bufferd data has been |
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220 * written, or the transport will not accept any more. |
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221 * |
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222 * In either case, transport_write semantics garuntee that our buffer will either be empty, or an on_write will be |
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223 * pending on the transport. |
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224 */ |
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225 err_t msg_buf_flush (struct msg_buf *buf, transport_t *transport, error_t *err) |
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226 { |
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227 ssize_t ret; |
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228 |
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229 // write |
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230 if ((ret = _transport_write_all(transport, buf->base, buf->off, err)) < 0) |
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231 goto error; |
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232 |
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233 if (ret) |
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234 // unbuffer the written data |
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235 msg_buf_drain(buf, ret); |
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236 |
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237 // ok |
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238 return SUCCESS; |
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239 |
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240 error: |
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241 return ERROR_CODE(err); |
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242 } |
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243 |
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244 /** |
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245 * Deinitialize msg_buf to release allocated buffers |
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246 */ |
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247 void msg_buf_deinit (struct msg_buf *buf) |
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248 { |
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249 // release |
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250 free(buf->base); |
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251 |
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252 // reset |
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253 buf->base = NULL; |
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254 buf->size = buf->off = 0; |
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255 } |
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256 |
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257 /** |
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258 * Message header |
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259 */ |
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260 struct msg_header { |
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261 /** Message length, including header */ |
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262 uint16_t len; |
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263 }; |
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264 |
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265 /** |
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266 * Message header size |
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267 */ |
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268 #define MSG_PROTO_HEADER_SIZE (sizeof(uint16_t)) |
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269 |
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270 /** |
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271 * Our state struct |
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272 */ |
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273 struct msg_proto { |
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274 /** The transport */ |
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275 transport_t *transport; |
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276 |
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277 /** User callbacks */ |
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278 const struct msg_proto_callbacks *cb_tbl; |
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279 |
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280 /** User callback argument */ |
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281 void *cb_arg; |
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282 |
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283 /** Input buffer */ |
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284 struct msg_buf in; |
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285 |
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286 /** Output buffer */ |
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287 struct msg_buf out; |
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288 }; |
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289 |
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290 /** |
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291 * Signal error to user |
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292 */ |
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293 static void msg_proto_error (struct msg_proto *proto, const error_t *err) |
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294 { |
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295 // invoke user callback |
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296 proto->cb_tbl->on_error(proto, err, proto->cb_arg); |
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297 } |
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298 |
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299 /** |
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300 * Attempt to read the current header from our input buffer. |
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301 * |
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302 * Returns >0 for full header, 0 for incomplete header, -err_t for error. |
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303 */ |
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304 static int msg_proto_peek_header (struct msg_proto *proto, struct msg_header *header, error_t *err) |
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305 { |
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306 if (proto->in.off < MSG_PROTO_HEADER_SIZE) |
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307 // not enough data for header |
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308 return 0; |
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309 |
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310 // read header |
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311 header->len = ntohs(*((uint16_t *) proto->in.base)); |
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312 |
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313 // bad header? |
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314 if (header->len < MSG_PROTO_HEADER_SIZE) |
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315 JUMP_SET_ERROR_STR(err, ERR_MISC, "message_header::len"); |
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316 |
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317 // ok, got header |
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318 return 1; |
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319 |
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320 error: |
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321 return -ERROR_CODE(err); |
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322 } |
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323 |
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324 /** |
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325 * Recieved a message with the given header, and a pointer to the message data |
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326 * |
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327 * XXX: what to do if the user callback destroys the msg_proto? |
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328 */ |
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329 static err_t msg_proto_on_msg (struct msg_proto *proto, struct msg_header *header, char *data, error_t *err) |
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330 { |
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331 (void) err; |
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332 |
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333 // invoke user callback |
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334 proto->cb_tbl->on_msg(proto, data, header->len - MSG_PROTO_HEADER_SIZE, proto->cb_arg); |
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335 |
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336 // XXX: handle user errors |
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337 return SUCCESS; |
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338 } |
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339 |
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340 static void msg_proto_on_read (transport_t *transport, void *arg) |
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341 { |
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342 struct msg_proto *proto = arg; |
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343 struct msg_header header; |
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344 ssize_t ret; |
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345 error_t err; |
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346 |
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347 // we might be able to read more than one message per event |
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348 do { |
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349 // try and read message length for incomplete message |
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350 if ((ret = msg_proto_peek_header(proto, &header, &err)) < 0) |
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351 goto error; |
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352 |
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353 // need to read more data? |
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354 if (!ret || header.len > proto->in.off) { |
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355 // msg_buf_read a minimum size, so passing a zero is OK |
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356 size_t to_read = ret ? header.len : 0; |
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357 |
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358 // read into our buffer |
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359 if ((ret = msg_buf_read(&proto->in, transport, to_read, &err)) < 0) |
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360 goto error; |
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361 |
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362 } else { |
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363 // handle full message |
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364 if (msg_proto_on_msg(proto, &header, proto->in.base + MSG_PROTO_HEADER_SIZE, &err)) |
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365 goto error; |
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366 |
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367 // remove the data from the buffer |
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368 msg_buf_drain(&proto->in, header.len); |
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369 } |
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370 } while (ret); |
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371 |
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372 // ok |
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373 return; |
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374 |
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375 error: |
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376 // notify user |
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377 msg_proto_error(proto, &err); |
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378 } |
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379 |
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380 static void msg_proto_on_write (transport_t *transport, void *arg) |
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381 { |
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382 struct msg_proto *proto = arg; |
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383 error_t err; |
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384 |
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385 // flush |
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386 if (msg_buf_flush(&proto->out, transport, &err)) |
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387 // notify user on transport errors |
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388 msg_proto_error(proto, &err); |
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389 } |
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390 |
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391 static void msg_proto_on_error (transport_t *transport, const error_t *err, void *arg) |
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392 { |
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393 struct msg_proto *proto = arg; |
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394 |
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395 (void) transport; |
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396 |
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397 // report to user |
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398 msg_proto_error(proto, err); |
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399 } |
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400 |
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401 static const struct transport_callbacks msg_proto_transport_callbacks = { |
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402 .on_read = msg_proto_on_read, |
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403 .on_write = msg_proto_on_write, |
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404 .on_error = msg_proto_on_error, |
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405 }; |
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406 |
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407 err_t msg_proto_create (struct msg_proto **proto_ptr, transport_t *transport, const struct msg_proto_callbacks *cb_tbl, void *cb_arg, error_t *err) |
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408 { |
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409 struct msg_proto *proto; |
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410 |
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411 // alloc |
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412 if ((proto = calloc(1, sizeof(*proto))) == NULL) |
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413 return ERR_MEM; |
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414 |
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415 // store |
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416 proto->transport = transport; |
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417 proto->cb_tbl = cb_tbl; |
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418 proto->cb_arg = cb_arg; |
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419 |
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420 // init |
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421 if ( |
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422 (ERROR_CODE(err) = msg_buf_init(&proto->in, 0)) |
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423 || (ERROR_CODE(err) = msg_buf_init(&proto->out, 0)) |
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424 ) |
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425 goto error; |
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426 |
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427 // setup transport |
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428 if ((ERROR_CODE(err) = transport_events(transport, TRANSPORT_READ | TRANSPORT_WRITE))) |
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429 goto error; |
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430 |
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431 transport_set_callbacks(transport, &msg_proto_transport_callbacks, proto); |
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432 |
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433 // ok |
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434 *proto_ptr = proto; |
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435 |
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436 return SUCCESS; |
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437 |
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438 error: |
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439 // release |
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440 msg_proto_destroy(proto); |
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441 |
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442 return ERROR_CODE(err); |
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443 } |
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444 |
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445 /** |
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446 * Build and write out the data for the given header |
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447 */ |
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448 static err_t msg_proto_write_header (struct msg_proto *proto, const struct msg_header *header, error_t *err) |
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449 { |
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450 char buf[MSG_PROTO_HEADER_SIZE]; |
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451 |
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452 // validate |
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453 if (header->len < MSG_PROTO_HEADER_SIZE) |
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454 return SET_ERROR(err, ERR_MISC); |
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455 |
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456 // build |
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457 *((uint16_t *) buf) = htons(header->len); |
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458 |
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459 // write |
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460 return msg_buf_write(&proto->out, proto->transport, buf, sizeof(buf), err); |
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461 } |
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462 |
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463 err_t msg_proto_send (struct msg_proto *proto, const void *data, size_t len, error_t *err) |
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464 { |
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465 struct msg_header header; |
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466 |
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467 // build header |
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468 header.len = MSG_PROTO_HEADER_SIZE + len; |
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469 |
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470 // write it |
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471 if ( |
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472 msg_proto_write_header(proto, &header, err) |
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473 || msg_buf_write(&proto->out, proto->transport, data, len, err) |
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474 ) |
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475 return ERROR_CODE(err); |
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476 |
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477 // ok |
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478 return SUCCESS; |
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479 } |
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480 |
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481 void msg_proto_destroy (struct msg_proto *proto) |
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482 { |
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483 // drop buffers |
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484 msg_buf_deinit(&proto->in); |
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485 msg_buf_deinit(&proto->out); |
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486 |
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487 // kill transport |
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488 transport_destroy(proto->transport); |
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489 |
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490 // release ourself |
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491 free(proto); |
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492 } |
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493 |